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Sample records for repetitive pet studies

  1. Protective effects of repetitive transcranial magnetic stimulation in a rat model of transient cerebral ischaemia: a microPET study

    International Nuclear Information System (INIS)

    Gao, Feng; Wang, Shuang; Guo, Yi; Lou, Min; Wu, Jimin; Ding, Meiping; Wang, Jing; Zhang, Hong; Tian, Mei

    2010-01-01

    Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive method to excite neurons in the brain. However, the underlying mechanism of its therapeutic effects in stroke remains unclear. The aim of this study was to investigate the neuroprotective effect of high-frequency rTMS in a rat model of transient cerebral ischaemia using positron emission tomography (PET). Sprague-Dawley rats (n=30) were anaesthetized with chloral hydrate and subjected to 90 min of intraluminal middle cerebral artery occlusion (MCAO) with subsequent reperfusion in three groups: control (n=10), rTMS (n=10), or sham-rTMS groups (n=10). In the rTMS group, rTMS was given 1 h after ischaemia and every 24 h for 7 days after MCAO. In all three groups, small-animal PET (microPET) imaging with 18 F-FDG was used to evaluate brain glucose metabolism. Apoptotic molecules were measured in the infarct margin using immunohistochemical staining. The neurological scores of the rats in the rTMS group were higher than in those of the control group over the whole 7-day observation period. The total, cortical and striatal infarct volumes were significantly less in the rTMS group than in the control group, as measured by 2,3,5-triphenyltetrazolium chloride staining. 18 F-FDG microPET images showed significantly higher standardized uptake values in the cortex and striatum in the rTMS group than in the control group in the affected hemisphere. The number of cells positive for caspase-3 was significantly lower in the rTMS group than in the control group, while the Bcl-2/Bax ratio was significantly higher in the rTMS group than in the control group. rTMS therapy increased glucose metabolism and inhibited apoptosis in the ischaemic hemisphere. 18 F-FDG PET could be used to monitor rTMS therapy in transient cerebral ischaemia in animal studies and in future clinical trials. (orig.)

  2. Protective effects of repetitive transcranial magnetic stimulation in a rat model of transient cerebral ischaemia: a microPET study

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Nuclear Medicine, Hangzhou, Zhejiang (China); Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Neurology, Hangzhou, Zhejiang (China); Zhejiang University Medical PET Center, Hangzhou, Zhejiang (China); Institute of Nuclear Medicine and Molecular Imaging of Zhejiang University, Hangzhou, Zhejiang (China); Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, Zhejiang (China); Wang, Shuang; Guo, Yi; Lou, Min; Wu, Jimin; Ding, Meiping [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Neurology, Hangzhou, Zhejiang (China); Wang, Jing; Zhang, Hong [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Nuclear Medicine, Hangzhou, Zhejiang (China); Zhejiang University Medical PET Center, Hangzhou, Zhejiang (China); Institute of Nuclear Medicine and Molecular Imaging of Zhejiang University, Hangzhou, Zhejiang (China); Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, Zhejiang (China); Tian, Mei [The University of Texas M.D. Anderson Cancer Center, Department of Experimental Diagnostic Imaging, Houston, TX (United States)

    2010-05-15

    Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive method to excite neurons in the brain. However, the underlying mechanism of its therapeutic effects in stroke remains unclear. The aim of this study was to investigate the neuroprotective effect of high-frequency rTMS in a rat model of transient cerebral ischaemia using positron emission tomography (PET). Sprague-Dawley rats (n=30) were anaesthetized with chloral hydrate and subjected to 90 min of intraluminal middle cerebral artery occlusion (MCAO) with subsequent reperfusion in three groups: control (n=10), rTMS (n=10), or sham-rTMS groups (n=10). In the rTMS group, rTMS was given 1 h after ischaemia and every 24 h for 7 days after MCAO. In all three groups, small-animal PET (microPET) imaging with {sup 18}F-FDG was used to evaluate brain glucose metabolism. Apoptotic molecules were measured in the infarct margin using immunohistochemical staining. The neurological scores of the rats in the rTMS group were higher than in those of the control group over the whole 7-day observation period. The total, cortical and striatal infarct volumes were significantly less in the rTMS group than in the control group, as measured by 2,3,5-triphenyltetrazolium chloride staining. {sup 18}F-FDG microPET images showed significantly higher standardized uptake values in the cortex and striatum in the rTMS group than in the control group in the affected hemisphere. The number of cells positive for caspase-3 was significantly lower in the rTMS group than in the control group, while the Bcl-2/Bax ratio was significantly higher in the rTMS group than in the control group. rTMS therapy increased glucose metabolism and inhibited apoptosis in the ischaemic hemisphere. {sup 18}F-FDG PET could be used to monitor rTMS therapy in transient cerebral ischaemia in animal studies and in future clinical trials. (orig.)

  3. Metabolic changes of cerebrum by repetitive transcranial magnetic stimulation over lateral cerebellum: a study with FDG PET.

    Science.gov (United States)

    Cho, Sang Soo; Yoon, Eun Jin; Bang, Sung Ae; Park, Hyun Soo; Kim, Yu Kyeong; Strafella, Antonio P; Kim, Sang Eun

    2012-09-01

    To better understand the functional role of cerebellum within the large-scale cerebellocerebral neural network, we investigated the changes of neuronal activity elicited by cerebellar repetitive transcranial magnetic stimulation (rTMS) using (18)F-fluorodeoxyglucose (FDG) and positron emission tomography (PET). Twelve right-handed healthy volunteers were studied with brain FDG PET under two conditions: active rTMS of 1 Hz frequency over the left lateral cerebellum and sham stimulation. Compared to the sham condition, active rTMS induced decreased glucose metabolism in the stimulated left lateral cerebellum, the areas known to be involved in voluntary motor movement (supplementary motor area and posterior parietal cortex) in the right cerebral hemisphere, and the areas known to be involved in cognition and emotion (orbitofrontal, medial frontal, and anterior cingulate gyri) in the left cerebral hemisphere. Increased metabolism was found in cognition- and language-related brain regions such as the left inferior frontal gyrus including Broca's area, bilateral superior temporal gyri including Wernicke's area, and bilateral middle temporal gyri. Left cerebellar rTMS also led to increased metabolism in the left cerebellar dentate nucleus and pons. These results demonstrate that rTMS over the left lateral cerebellum modulates not only the target region excitability but also excitability of remote, but interconnected, motor-, language-, cognition-, and emotion-related cerebral regions. They provide further evidence that the cerebellum is involved not only in motor-related functions but also in higher cognitive abilities and emotion through the large-scale cerebellocereberal neural network.

  4. PET studies in epilepsy

    Science.gov (United States)

    Sarikaya, Ismet

    2015-01-01

    Various PET studies, such as measurements of glucose, serotonin and oxygen metabolism, cerebral blood flow and receptor bindings are availabe for epilepsy. 18Fluoro-2-deoxyglucose (18F-FDG) PET imaging of brain glucose metabolism is a well established and widely available technique. Studies have demonstrated that the sensitivity of interictal FDG-PET is higher than interictal SPECT and similar to ictal SPECT for the lateralization and localization of epileptogenic foci in presurgical patients refractory to medical treatments who have noncontributory EEG and MRI. In addition to localizing epileptogenic focus, FDG-PET provide additional important information on the functional status of the rest of the brain. The main limitation of interictal FDG-PET is that it cannot precisely define the surgical margin as the area of hypometabolism usually extends beyond the epileptogenic zone. Various neurotransmitters (GABA, glutamate, opiates, serotonin, dopamine, acethylcholine, and adenosine) and receptor subtypes are involved in epilepsy. PET receptor imaging studies performed in limited centers help to understand the role of neurotransmitters in epileptogenesis, identify epileptic foci and investigate new treatment approaches. PET receptor imaging studies have demonstrated reduced 11C-flumazenil (GABAA-cBDZ) and 18F-MPPF (5-HT1A serotonin) and increased 11C-cerfentanil (mu opiate) and 11C-MeNTI (delta opiate) bindings in the area of seizure. 11C-flumazenil has been reported to be more sensitive than FDG-PET for identifying epileptic foci. The area of abnormality on GABAAcBDZ and opiate receptor images is usually smaller and more circumscribed than the area of hypometabolism on FDG images. Studies have demonstrated that 11C-alpha-methyl-L-tryptophan PET (to study synthesis of serotonin) can detect the epileptic focus within malformations of cortical development and helps in differentiating epileptogenic from non-epileptogenic tubers in patients with tuberous sclerosis complex

  5. PET studies in dementia

    International Nuclear Information System (INIS)

    Herholz, K.

    2003-01-01

    Measurement of local cerebral glucose metabolism (lCMRGlc) by positron emission tomography (PET) and 18 F-2-fluoro-2-deoxy-D-glucose (FDG) has become a standard technique during the past 20 years and is now available at many university hospitals in all highly developed countries. Many studies have documented a close relation between lCMRGlc and localized cognitive functions, such as language and visuoconstructive abilities. Alzheimer's disease (AD) is characterized by regional impairment of cerebral glucose metabolism in neocortical association areas (posterior cingulate, temporoparietal and frontal multimodal association cortex), whereas primary visual and sensorimotor cortex, basal ganglia, and cerebellum are relatively well preserved. In a multicenter study comprising 10 PET centers (Network for Efficiency and Standardization of Dementia Diagnosis, NEST-DD) that employed an automated voxel-based analysis of FDG PET images, the distinction between controls and AD patients was 93% sensitive and 93% specific, and even in very mild dementia (at Mini Mental Status Examination (MMSE) 24 or higher) sensitivity was still 84% at 93% specificity. Significantly abnormal metabolism in mild cognitive deficit (MCI) indicates a high risk to develop dementia within the next two years. Reduced neocortical glucose metabolism can probably be detected with FDG PET in AD on average one year before onset of subjective cognitive impairment. In addition to glucose metabolism, specific tracers for dopamine synthesis ( 18 F-F-DOPA) and for ( 11 C-MP4A) are of interest for differentiation among dementia subtypes. Cortical acetylcholine esterase activity (AChE) activity is significantly lower in patients with AD or with dementia with Lewy bodies (DLB) than in age-matched normal controls. In LBD there is also impairment of dopamine synthesis, similar to Parkinson disease. (author) 115 refs

  6. PET studies in dementia

    Energy Technology Data Exchange (ETDEWEB)

    Herholz, K. [Neurologische Universitaetsklinik and Max-Planck-Inst. fuer neurologische Forschung, Koeln (Germany)

    2003-04-01

    Measurement of local cerebral glucose metabolism (lCMRGlc) by positron emission tomography (PET) and {sup 18}F-2-fluoro-2-deoxy-D-glucose (FDG) has become a standard technique during the past 20 years and is now available at many university hospitals in all highly developed countries. Many studies have documented a close relation between lCMRGlc and localized cognitive functions, such as language and visuoconstructive abilities. Alzheimer's disease (AD) is characterized by regional impairment of cerebral glucose metabolism in neocortical association areas (posterior cingulate, temporoparietal and frontal multimodal association cortex), whereas primary visual and sensorimotor cortex, basal ganglia, and cerebellum are relatively well preserved. In a multicenter study comprising 10 PET centers (Network for Efficiency and Standardization of Dementia Diagnosis, NEST-DD) that employed an automated voxel-based analysis of FDG PET images, the distinction between controls and AD patients was 93% sensitive and 93% specific, and even in very mild dementia (at Mini Mental Status Examination (MMSE) 24 or higher) sensitivity was still 84% at 93% specificity. Significantly abnormal metabolism in mild cognitive deficit (MCI) indicates a high risk to develop dementia within the next two years. Reduced neocortical glucose metabolism can probably be detected with FDG PET in AD on average one year before onset of subjective cognitive impairment. In addition to glucose metabolism, specific tracers for dopamine synthesis ({sup 18}F-F-DOPA) and for ({sup 11}C-MP4A) are of interest for differentiation among dementia subtypes. Cortical acetylcholine esterase activity (AChE) activity is significantly lower in patients with AD or with dementia with Lewy bodies (DLB) than in age-matched normal controls. In LBD there is also impairment of dopamine synthesis, similar to Parkinson disease. (author) 115 refs.

  7. Understanding communicative actions: a repetitive TMS study.

    Science.gov (United States)

    Stolk, Arjen; Noordzij, Matthijs L; Volman, Inge; Verhagen, Lennart; Overeem, Sebastiaan; van Elswijk, Gijs; Bloem, Bas; Hagoort, Peter; Toni, Ivan

    2014-02-01

    Despite the ambiguity inherent in human communication, people are remarkably efficient in establishing mutual understanding. Studying how people communicate in novel settings provides a window into the mechanisms supporting the human competence to rapidly generate and understand novel shared symbols, a fundamental property of human communication. Previous work indicates that the right posterior superior temporal sulcus (pSTS) is involved when people understand the intended meaning of novel communicative actions. Here, we set out to test whether normal functioning of this cerebral structure is required for understanding novel communicative actions using inhibitory low-frequency repetitive transcranial magnetic stimulation (rTMS). A factorial experimental design contrasted two tightly matched stimulation sites (right pSTS vs left MT+, i.e., a contiguous homotopic task-relevant region) and tasks (a communicative task vs a visual tracking task that used the same sequences of stimuli). Overall task performance was not affected by rTMS, whereas changes in task performance over time were disrupted according to TMS site and task combinations. Namely, rTMS over pSTS led to a diminished ability to improve action understanding on the basis of recent communicative history, while rTMS over MT+ perturbed improvement in visual tracking over trials. These findings qualify the contributions of the right pSTS to human communicative abilities, showing that this region might be necessary for incorporating previous knowledge, accumulated during interactions with a communicative partner, to constrain the inferential process that leads to action understanding. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Surface modification of PET films using dielectric barrier discharge driven by repetitive nanosecond-pulses

    International Nuclear Information System (INIS)

    Shao Tao; Zhang Cheng; Long Kaihua; Wang Jue; Zhang Dongdong; Yan Ping; Zhou Yuanxiang

    2010-01-01

    In this paper, surface treatment of PET films for improving the hydrophilicity using DBD excited by unipolar nanosecond-pulses is presented. Homogeneous and filamentary discharge are obtained under certain experimental conditions and then used to modify the surface of PET films. The properties of PET films before and after treatment are characterized with water contact angle measurement, atomic force microscope and X-ray photoelectron spectroscope. The experimental results show that static water contact angles decrease after DBD plasma treatment and the observed contact angle is changed from 80 degree for the untreated samples to 20 degree after treatment. However, the decrease of contact angles is not continuous and it will reach a saturation state after certain treatment time. The improvement of surface hydrophilicity can be attributed to the enhancement of the surface roughness and introduction of oxygen-containing polar functional groups. In contrast with the filamentary DBD treatment, the homogenous DBD is more effective in PET surface treatment. (authors)

  9. The role of short-term memory impairment in nonword repetition, real word repetition, and nonword decoding: A case study.

    Science.gov (United States)

    Peter, Beate

    2018-01-01

    In a companion study, adults with dyslexia and adults with a probable history of childhood apraxia of speech showed evidence of difficulty with processing sequential information during nonword repetition, multisyllabic real word repetition and nonword decoding. Results suggested that some errors arose in visual encoding during nonword reading, all levels of processing but especially short-term memory storage/retrieval during nonword repetition, and motor planning and programming during complex real word repetition. To further investigate the role of short-term memory, a participant with short-term memory impairment (MI) was recruited. MI was confirmed with poor performance during a sentence repetition and three nonword repetition tasks, all of which have a high short-term memory load, whereas typical performance was observed during tests of reading, spelling, and static verbal knowledge, all with low short-term memory loads. Experimental results show error-free performance during multisyllabic real word repetition but high counts of sequence errors, especially migrations and assimilations, during nonword repetition, supporting short-term memory as a locus of sequential processing deficit during nonword repetition. Results are also consistent with the hypothesis that during complex real word repetition, short-term memory is bypassed as the word is recognized and retrieved from long-term memory prior to producing the word.

  10. Decay correction methods in dynamic PET studies

    International Nuclear Information System (INIS)

    Chen, K.; Reiman, E.; Lawson, M.

    1995-01-01

    In order to reconstruct positron emission tomography (PET) images in quantitative dynamic studies, the data must be corrected for radioactive decay. One of the two commonly used methods ignores physiological processes including blood flow that occur at the same time as radioactive decay; the other makes incorrect use of time-accumulated PET counts. In simulated dynamic PET studies using 11 C-acetate and 18 F-fluorodeoxyglucose (FDG), these methods are shown to result in biased estimates of the time-activity curve (TAC) and model parameters. New methods described in this article provide significantly improved parameter estimates in dynamic PET studies

  11. Small Animal [18F]FDG PET Imaging for Tumor Model Study

    International Nuclear Information System (INIS)

    Woo, Sang Keun; Kim, Kyeong Min; Cheon, Gi Jeong

    2008-01-01

    PET allows non-invasive, quantitative and repetitive imaging of biological function in living animals. Small animal PET imaging with [ 18 F]FDG has been successfully applied to investigation of metabolism, receptor, ligand interactions, gene expression, adoptive cell therapy and somatic gene therapy. Experimental condition of animal handling impacts on the biodistribution of [ 18 F]FDG in small animal study. The small animal PET and CT images were registered using the hardware fiducial markers and small animal contour point. Tumor imaging in small animal with small animal [ 18 F]FDG PET should be considered fasting, warming, and isoflurane anesthesia level. Registered imaging with small animal PET and CT image could be useful for the detection of tumor. Small animal experimental condition of animal handling and registration method will be of most importance for small lesion detection of metastases tumor model

  12. Understanding communicative actions : A repetitive TMS study

    NARCIS (Netherlands)

    Stolk, Arjen; Noordzij, Matthijs Leendert; Volman, Inge; Verhagen, Lennart; Overeem, Sebastiaan; van Elswijk, Gijs; Bloem, Bas; Hagoort, Peter; Toni, Ivan

    2014-01-01

    Despite the ambiguity inherent in human communication, people are remarkably efficient in establishing mutual understanding. Studying how people communicate in novel settings provides a window into the mechanisms supporting the human competence to rapidly generate and understand novel shared

  13. Understanding communicative actions: A repetitive TMS study

    NARCIS (Netherlands)

    Stolk, A.; Noordzij, M.L.; Volman, I.A.C.; Verhagen, L.; Overeem, S.; Elswijk, G.A.F. van; Bloem, B.R.; Hagoort, P.; Toni, I.

    2014-01-01

    Despite the ambiguity inherent in human communication, people are remarkably efficient in establishing mutual understanding. Studying how people communicate in novel settings provides a window into the mechanisms supporting the human competence to rapidly generate and understand novel shared

  14. Understanding communicative actions: A repetitive TMS study

    NARCIS (Netherlands)

    Stolk, A.; Noordzij, M.L.; Volman, I.A.C.; Verhagen, L.; Overeem, S.; Elswijk, G.A.F. van; Bloem, B.R.; Hagoort, Peter; Toni, I.

    2013-01-01

    Despite the ambiguity inherent in human communication, people are remarkably efficient in establishing mutual understanding. Studying how people communicate in novel settings provides a window into the mechanisms supporting the human competence to rapidly generate and understand novel shared

  15. High-repetition-rate hydrogen chamber: Preliminary studies

    International Nuclear Information System (INIS)

    1967-01-01

    This report is a conclusion to the tests realised with an experimental bubbles chamber in view to study the possibilities to increase the repetition rate. The more important parameters (the evolution of the bubbles, the expansion system) are considered in a theoretical way. Then the hardware is described. To end, experimental results are compared with the first evaluations. The calculations and the experimentation are against an oscillation system for the expansion. A system with a locking is to he considered. (authors) [fr

  16. Basic study of entire whole-body PET scanners based on the OpenPET geometry

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Eiji, E-mail: rush@nirs.go.j [National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Yamaya, Taiga; Nishikido, Fumihiko; Inadama, Naoko; Murayama, Hideo [National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan)

    2010-09-21

    A conventional PET scanner has a 15-25 cm axial field-of-view (FOV) and images a whole body using about six bed positions. An OpenPET geometry can extend the axial FOV with a limited number of detectors. The entire whole-body PET scanner must be able to process a large amount of data effectively. In this work, we study feasibility of the fully 3D entire whole-body PET scanner using the GATE simulation. The OpenPET has 12 block detector rings with the ring diameter of 840 mm and each block detector ring consists of 48 depth-of-interaction (DOI) detectors. The OpenPET has the axial length of 895.95 mm with five parts of 58.95 mm open gaps. The OpenPET has higher single data loss than a conventional PET scanner at grouping circuits. NECR of the OpenPET decreases by single data loss. But single data loss is mitigated by separating the axially arranged detector into two parts. Also, multiple coincidences are found to be important for the entire whole-body PET scanner. The entire whole-body PET scanner with the OpenPET geometry promises to provide a large axial FOV with the open space and to have sufficient performance values. But single data loss at the grouping circuits and multiple coincidences are limited to the peak noise equivalent count rate (NECR) for the entire whole-body PET scanner.

  17. 'Number-forms' in neuroimaging?;- a PET activation study

    International Nuclear Information System (INIS)

    Cowell, S.F.; Code, C.; Harasty, J.; Egan, G.F.; Watson, J.D.G.; University of New South Wales,; Royal Prince Alfred Hospital, Sydney, NSW; University of Melbourne, VIC; University of Exeter,

    2000-01-01

    Full text: In 1880 Francis Galton reported a mental imagery study in which imagers were able to describe and draw arithmetic operations called 'number-forms' (NF). While many studies have reported NFs, little is known about their neural basis. We report a PET case study of a normal volunteer who invoked NFs during mental arithmetic tasks. This PET study used two conditions, repetition and calculation, presented bi-aurally while the subject was blindfolded. The calculation condition required the subject to say out loud the answers to arithmetic tasks, eg. 'nineteen minus seven'. A post-test protocol for vividness of visual imagery during calculation (PVVIC), based on the interviews of Galton (1880) and Seron and colleagues (1992), identified AF, a 43year-old women, as the highest imager (PVVIC - 95%) from a group of 12 normal volunteers. She was able to accurately describe and draw a well-used imagery strategy for mental arithmetic. Her results were contrasted with non-imager, FM (PVVIC - 10%). AF's MRI guided PET results showed significant rCBF activations during the calculation tasks including the right precuneus, right superior frontal gyrus (BA8), left superior parietal lobe (BA7), left visual cortex, medial thalamus and cerebellum. Except for the activation in the right BA8, common to both subjects, AF's areas were not activated by FM. These data confirm previous PET findings that the precuneus plays a major role in mental imagery and point to a neural network for mental imagery during simple calculation. AF's imagery strategies could be the first number-forms reported in a neuroimaging study. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

  18. Pharmacological studies of the lung with PET

    International Nuclear Information System (INIS)

    Syrota, A.

    1986-10-01

    Positron emission tomography (PET), known to be used for lung ventilation and perfusion studies, can also be used in pharmacology to obtain information that is otherwise not available. The lung takes up biologically active substances which can be inactivated or activated, and synthesises and releases others. Such information in man has been obtained from samples of human lungs, or from in vivo first-pass studies, invasive or not, as well as from in vivo kinetic studies using external detection methods with scintillation cameras. PET provides now quantitative regional data in the human lung

  19. PET-Studies in parkinson's disease

    International Nuclear Information System (INIS)

    Schwarz, J.

    2002-01-01

    Positron-emission-tomography (PET) has enabled to study the metabolism and blood flow in specific brain areas. Besides, there is a variety of radiotracers that allow quantification of the function of distinct molecules. In respect to Parkinson's disease, PET allowed for the first time to assess the number of dopaminergic neurons in vivo. Thus, helping confirming a dopaminergic deficit, measuring disease progression and also help to determine the function of dopaminergic grafts. Current research has shifted to determine the role of related neurotransmitter systems in the pathophysiology of Parkinson's disease. (orig.) [de

  20. Receptor study of psychiatric disorders using PET

    International Nuclear Information System (INIS)

    Suhara, Tetsuya

    1992-01-01

    Recent receptor studies of psychiatric disorders using PET have been focused on the change in the number of D 2 dopamine receptors in the striatum of drug-naive schizophrenic patients. One study confirmed an increase in D 2 receptors, while another study denied it. Although there were some differences in the approaches of the two groups, the reason for the discrepancy is not clear yet. Looking to psychiatric disorders other than schizophrenia, our recent study revealed a possible role of dopamine D 1 receptors in bipolar mood disorders. However, some problems must be resolved for further receptor studies with PET. For example, our recent study shows that desipamine decreases the in vivo binding of dopramine D 1 and D 2 receptors whereas these is no effect on dopamine D 1 and D 2 receptors in vitro. Additionally significant methodological problems lie in the method of evaluation of the non-specific binding and the effect of endogenous neurotransmitters. Moreover, difficulties in the diagnosis of psychiatric disorders and ethical problems in psychiatric research are critical factors in receptor studies with PET in psychiatric disorders. (author)

  1. Repetition suppression and repetition enhancement underlie auditory memory-trace formation in the human brain: an MEG study.

    Science.gov (United States)

    Recasens, Marc; Leung, Sumie; Grimm, Sabine; Nowak, Rafal; Escera, Carles

    2015-03-01

    The formation of echoic memory traces has traditionally been inferred from the enhanced responses to its deviations. The mismatch negativity (MMN), an auditory event-related potential (ERP) elicited between 100 and 250ms after sound deviation is an indirect index of regularity encoding that reflects a memory-based comparison process. Recently, repetition positivity (RP) has been described as a candidate ERP correlate of direct memory trace formation. RP consists of repetition suppression and enhancement effects occurring in different auditory components between 50 and 250ms after sound onset. However, the neuronal generators engaged in the encoding of repeated stimulus features have received little interest. This study intends to investigate the neuronal sources underlying the formation and strengthening of new memory traces by employing a roving-standard paradigm, where trains of different frequencies and different lengths are presented randomly. Source generators of repetition enhanced (RE) and suppressed (RS) activity were modeled using magnetoencephalography (MEG) in healthy subjects. Our results show that, in line with RP findings, N1m (~95-150ms) activity is suppressed with stimulus repetition. In addition, we observed the emergence of a sustained field (~230-270ms) that showed RE. Source analysis revealed neuronal generators of RS and RE located in both auditory and non-auditory areas, like the medial parietal cortex and frontal areas. The different timing and location of neural generators involved in RS and RE points to the existence of functionally separated mechanisms devoted to acoustic memory-trace formation in different auditory processing stages of the human brain. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. PET

    DEFF Research Database (Denmark)

    Mariager, Rasmus Mølgaard; Schmidt, Regin; Heiberg, Morten Rievers

    PET handler om den hemmelige tjenestes arbejde under den kolde krig 1945-1989. Her fortæller Regin Schmidt, Rasmus Mariager og Morten Heiberg om de mest dramatiske og interessante sager fra PET's arkiv. PET er på flere måder en udemokratisk institution, der er sat til at vogte over demokratiet....... Dens virksomhed er skjult for offentligheden, den overvåger borgernes aktiviteter, og den registrerer følsomme personoplysninger. Historien om PET rejser spørgsmålet om, hvad man skal gøre, når befolkningen i et demokrati er kritisk indstillet over for overvågningen af lovlige politiske aktiviteter......, mens myndighederne mener, at det er nødvendigt for at beskytte demokratiet. PET er på en gang en fortælling om konkrete aktioner og begivenheder i PET's arbejde og et stykke Danmarkshistorie. Det handler om overvågning, spioner, politisk ekstremisme og international terrorisme.  ...

  3. MRI-assisted PET motion correction for neurologic studies in an integrated MR-PET scanner.

    Science.gov (United States)

    Catana, Ciprian; Benner, Thomas; van der Kouwe, Andre; Byars, Larry; Hamm, Michael; Chonde, Daniel B; Michel, Christian J; El Fakhri, Georges; Schmand, Matthias; Sorensen, A Gregory

    2011-01-01

    Head motion is difficult to avoid in long PET studies, degrading the image quality and offsetting the benefit of using a high-resolution scanner. As a potential solution in an integrated MR-PET scanner, the simultaneously acquired MRI data can be used for motion tracking. In this work, a novel algorithm for data processing and rigid-body motion correction (MC) for the MRI-compatible BrainPET prototype scanner is described, and proof-of-principle phantom and human studies are presented. To account for motion, the PET prompt and random coincidences and sensitivity data for postnormalization were processed in the line-of-response (LOR) space according to the MRI-derived motion estimates. The processing time on the standard BrainPET workstation is approximately 16 s for each motion estimate. After rebinning in the sinogram space, the motion corrected data were summed, and the PET volume was reconstructed using the attenuation and scatter sinograms in the reference position. The accuracy of the MC algorithm was first tested using a Hoffman phantom. Next, human volunteer studies were performed, and motion estimates were obtained using 2 high-temporal-resolution MRI-based motion-tracking techniques. After accounting for the misalignment between the 2 scanners, perfectly coregistered MRI and PET volumes were reproducibly obtained. The MRI output gates inserted into the PET list-mode allow the temporal correlation of the 2 datasets within 0.2 ms. The Hoffman phantom volume reconstructed by processing the PET data in the LOR space was similar to the one obtained by processing the data using the standard methods and applying the MC in the image space, demonstrating the quantitative accuracy of the procedure. In human volunteer studies, motion estimates were obtained from echo planar imaging and cloverleaf navigator sequences every 3 s and 20 ms, respectively. Motion-deblurred PET images, with excellent delineation of specific brain structures, were obtained using these 2 MRI

  4. High-repetition-rate hydrogen chamber: Preliminary studies; Chambre a hydrogene a haut taux de repetition: Etudes preliminaires

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1967-01-01

    This report is a conclusion to the tests realised with an experimental bubbles chamber in view to study the possibilities to increase the repetition rate. The more important parameters (the evolution of the bubbles, the expansion system) are considered in a theoretical way. Then the hardware is described. To end, experimental results are compared with the first evaluations. The calculations and the experimentation are against an oscillation system for the expansion. A system with a locking is to he considered. (authors) [French] Ce rapport est une conclusion aux essais realises avec une chambre a bulles experimentale en vue d'etudier les possibilites d'accroitre les taux de repetition. Les parametres les plus importants (evolution des bulles, mecanique de la detente) sont etudies par voie theorique. Puis l'appareillage est decrit. Enfin, les resultats experimentaux sont compares aux evaluations donnees au debut. Ces calculs et cette experimentation ne sont pas en faveur d'un systeme oscillant pour la detente et il faut envisager un systeme avec verrouillage. (auteurs)

  5. MR-assisted PET Motion Correction for eurological Studies in an Integrated MR-PET Scanner

    Science.gov (United States)

    Catana, Ciprian; Benner, Thomas; van der Kouwe, Andre; Byars, Larry; Hamm, Michael; Chonde, Daniel B.; Michel, Christian J.; El Fakhri, Georges; Schmand, Matthias; Sorensen, A. Gregory

    2011-01-01

    Head motion is difficult to avoid in long PET studies, degrading the image quality and offsetting the benefit of using a high-resolution scanner. As a potential solution in an integrated MR-PET scanner, the simultaneously acquired MR data can be used for motion tracking. In this work, a novel data processing and rigid-body motion correction (MC) algorithm for the MR-compatible BrainPET prototype scanner is described and proof-of-principle phantom and human studies are presented. Methods To account for motion, the PET prompts and randoms coincidences as well as the sensitivity data are processed in the line or response (LOR) space according to the MR-derived motion estimates. After sinogram space rebinning, the corrected data are summed and the motion corrected PET volume is reconstructed from these sinograms and the attenuation and scatter sinograms in the reference position. The accuracy of the MC algorithm was first tested using a Hoffman phantom. Next, human volunteer studies were performed and motion estimates were obtained using two high temporal resolution MR-based motion tracking techniques. Results After accounting for the physical mismatch between the two scanners, perfectly co-registered MR and PET volumes are reproducibly obtained. The MR output gates inserted in to the PET list-mode allow the temporal correlation of the two data sets within 0.2 s. The Hoffman phantom volume reconstructed processing the PET data in the LOR space was similar to the one obtained processing the data using the standard methods and applying the MC in the image space, demonstrating the quantitative accuracy of the novel MC algorithm. In human volunteer studies, motion estimates were obtained from echo planar imaging and cloverleaf navigator sequences every 3 seconds and 20 ms, respectively. Substantially improved PET images with excellent delineation of specific brain structures were obtained after applying the MC using these MR-based estimates. Conclusion A novel MR-based MC

  6. MR-assisted PET motion correction in simultaneous PET/MRI studies of dementia subjects.

    Science.gov (United States)

    Chen, Kevin T; Salcedo, Stephanie; Chonde, Daniel B; Izquierdo-Garcia, David; Levine, Michael A; Price, Julie C; Dickerson, Bradford C; Catana, Ciprian

    2018-03-08

    Subject motion in positron emission tomography (PET) studies leads to image blurring and artifacts; simultaneously acquired magnetic resonance imaging (MRI) data provides a means for motion correction (MC) in integrated PET/MRI scanners. To assess the effect of realistic head motion and MR-based MC on static [ 18 F]-fluorodeoxyglucose (FDG) PET images in dementia patients. Observational study. Thirty dementia subjects were recruited. 3T hybrid PET/MR scanner where EPI-based and T 1 -weighted sequences were acquired simultaneously with the PET data. Head motion parameters estimated from high temporal resolution MR volumes were used for PET MC. The MR-based MC method was compared to PET frame-based MC methods in which motion parameters were estimated by coregistering 5-minute frames before and after accounting for the attenuation-emission mismatch. The relative changes in standardized uptake value ratios (SUVRs) between the PET volumes processed with the various MC methods, without MC, and the PET volumes with simulated motion were compared in relevant brain regions. The absolute value of the regional SUVR relative change was assessed with pairwise paired t-tests testing at the P = 0.05 level, comparing the values obtained through different MR-based MC processing methods as well as across different motion groups. The intraregion voxelwise variability of regional SUVRs obtained through different MR-based MC processing methods was also assessed with pairwise paired t-tests testing at the P = 0.05 level. MC had a greater impact on PET data quantification in subjects with larger amplitude motion (higher than 18% in the medial orbitofrontal cortex) and greater changes were generally observed for the MR-based MC method compared to the frame-based methods. Furthermore, a mean relative change of ∼4% was observed after MC even at the group level, suggesting the importance of routinely applying this correction. The intraregion voxelwise variability of regional SUVRs

  7. Influence of PET/CT-introduction on PET scanning frequency and indications. Results of a multicenter study

    International Nuclear Information System (INIS)

    Stergar, H.; Bockisch, A.; Eschmann, S.M.; Krause, B.J.; Roedel, R.; Tiling, R.; Weckesser, M.

    2007-01-01

    Aim: to evaluate the influence of the introduction of combined PET/CT scanners into clinical routine. This investigation addresses the quantitative changes between PET/CT and stand alone PET. Methods: the study included all examinations performed on stand alone PET- or PET/CT-scanners within 12 month prior to and after implementation of PET/CT. The final data analysis included five university hospitals and a total number of 15 497 exams. We distinguished exams on stand alone tomographs prior to and after installation of the combined device as well as PET/CT scans particularly with regard to disease entities. Various further parameters were investigated. Results: the overall number of PET scans (PET and PET/CT) rose by 146% while the number of scans performed on stand alone scanners declined by 22%. Only one site registered an increase in stand alone PET. The number of exams for staging in oncology increased by 196% while that of cardiac scans decreased by 35% and the number of scans in neurology rose by 47%. The use of scans for radiotherapy planning increased to 7% of all PET/CT studies. The increase of procedures for so-called classic PET oncology indications was moderate compared to the more common tumors. An even greater increase was observed in some rare entities. Conclusions: the introduction of PET/CT led to more than a doubling of overall PET procedures with a main focus on oncology. Some of the observed changes in scanning frequency may be caused by a rising availability of new radiotracers and advancements of competing imaging methods. Nevertheless the evident increase in the use of PET/CT for the most common tumour types demonstrates its expanding role in cancer staging. The combination of molecular and morphologic imaging has not only found its place but is still gaining greater importance with new developments in technology and radiochemistry. (orig.)

  8. Serotonin synthesis studied with positron emission tomography, (PET)

    DEFF Research Database (Denmark)

    Honoré, Per Gustaf Hartvig; Lundquist, Pinelopi

    Positron emission tomography (PET) has the potential to study the biosynthesis and release of serotonin (5HT) at brain serotonergic neurons. PET requires probe compounds with specific attributes to enable imaging and quantification of biological processes. This section focuses on probes to measure...

  9. A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner

    International Nuclear Information System (INIS)

    Slates, R.B.; Farahani, K.; Marsden, P.K.; Taylor, J.; Summers, P.E.; Williams, S.; Beech, J.

    1999-01-01

    We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T 2 -weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner. (author)

  10. PET IMAGING STUDIES IN DRUG ABUSE RESEARCH.

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, J.S.; Volkow, N.D.; Ding, Y.S.; Logan, J.; Wang, G.J.

    2001-01-29

    . This will be followed by highlights of PET studies of the acute effects of the psychostimulant drugs cocaine and methylphenidate (ritalin) and studies of the chronic effects of cocaine and of tobacco smoke on the human brain. This chapter concludes with the description of a study which uses brain imaging coupled with a specific pharmacological challenge to address the age-old question of why some people who experiment with drugs become addicted while others do not.

  11. The study of multiple PET reconstructed parameter

    International Nuclear Information System (INIS)

    Yin, D. Y.; Tian, J.

    2000-01-01

    PET, compared with SPECT, uses some similar techniques in image reconstruction, on the other hand, there are some difference on the techniques. A phantom experiment was conducted and the result was evaluated objectively through quantitative analysis in order to find ideal filter and cutoff frequency (Fc) for clinical application. The PET phantom have 6 solid inserts (cold) in the upper half and 6 hollow ones (hot) in the lower part. The middle insert is 1cm in diameter, the outer five have diameters of 1 to 3cm respectively. The phantom filled with 111 MBq 18 FDG and studied with segmentation acquisition. 25 set of images were reconstructed using HANN, HAMM, PARZEN, BUTTERWORTH, BUTTERWORTH2 filter and 0.1, 0.2, 0.3, 0.4, 0.5 Fe successively.A ROI of 4*4 pixels was drawn over middle 1 cm, outer 1cm, 3 cm cold column area and background area, the ratio between the ROI of cold column and background was calculated to evaluate the image contrast. A ROI of 15*15 pixels was drawn on the background area to get s.d as a judgement of image noise. A profile curve was drawn on the hollow column of middle 1 cm and outer 1 cm and their FWHM were compared with the real diameter to reflect linearity. With the same Fc, the contrast using HANN and HAMM filter was superior to other filter, The effect of the filter on image noise is listed in high to low order as HAMM, HANN, BUTTERWORTH, PARZEN and BUTTERWORTH2. The higher Fc, the higher image noise. The FWHM will increases as the Fc value decreases. With same Fc, the FWHM of different filter from small to big is HAMM, BUTTERWORTH, HANN, PARZEN, BUTTERWORTH2. The outer FWHM is larger than the middle one. For brain image, we suggest HAMM and HANN with Fc 0.3, 0.4 For image demanding lower resolution, we suggest BUTTERWORTH with Fc 0.4, 0.5, 2. For hot image, we can increase Fc to get high resolution. The FWHM value closed to the real value when HANN, HANN with Fc 0.3 and BUTTERWORTH with Fc 0.2. The 5% difference of FWHM between

  12. PET studies in Alzheimer disease and other degenerative dementias

    International Nuclear Information System (INIS)

    Jeong, Yong; Na, Duk L.

    2003-01-01

    Neurodegenerative disorders cause a variety of dementia including Alzheimer disease, frontotemporal dementia, dementia with Lewy bodies, corticobasal degeneration, progressive supranuclear palsy, and Huntington's disease. PET scan is useful for early detection and differential diagnosis of theses dementing disorders. Also, it provides valuable information about clinico-anatomical correlation, allowing better understanding of function of brain. Here we discuss recent achievements PET studies regarding these dementing disorders. Future progress in PET technology, new tracers, and image analysis will play an important role in further clarifying the disease pathophysiology and brain functions

  13. Reliability of semiquantitative 18F-FDG PET parameters derived from simultaneous brain PET/MRI: A feasibility study

    International Nuclear Information System (INIS)

    Jena, Amarnath; Taneja, Sangeeta; Goel, Reema; Renjen, Pushpendranath; Negi, Pradeep

    2014-01-01

    Purpose: Simultaneous brain PET/MRI faces an important issue of validation of accurate MRI based attenuation correction (AC) method for precise quantitation of brain PET data unlike in PET/CT systems where the use of standard, validated CT based AC is routinely available. The aim of this study was to investigate the feasibility of evaluation of semiquantitative 18 F-FDG PET parameters derived from simultaneous brain PET/MRI using ultrashort echo time (UTE) sequences for AC and to assess their agreement with those obtained from PET/CT examination. Methods: Sixteen patients (age range 18–73 years; mean age 49.43 (19.3) years; 13 men 3 women) underwent simultaneous brain PET/MRI followed immediately by PET/CT. Quantitative analysis of brain PET images obtained from both studies was undertaken using Scenium v.1 brain analysis software package. Twenty ROIs for various brain regions were system generated and 6 semiquantitative parameters including maximum standardized uptake value (SUV max), SUV mean, minimum SUV (SUV min), minimum standard deviation (SD min), maximum SD (SD max) and SD from mean were calculated for both sets of PET data for each patient. Intra-class correlation coefficients (ICCs) were determined to assess agreement between the various semiquantitative parameters for the two PET data sets. Results: Intra-class co-relation between the two PET data sets for SUV max, SUV mean and SD max was highly significant (p < 0.00) for all the 20 predefined brain regions with ICC > 0.9. SD from mean was also found to be statistically significant for all the predefined brain regions with ICC > 0.8. However, SUV max and SUV mean values obtained from PET/MRI were significantly lower compared to those of PET/CT for all the predefined brain regions. Conclusion: PET quantitation accuracy using the MRI based UTE sequences for AC in simultaneous brain PET/MRI is reliable in a clinical setting, being similar to that obtained using PET/CT

  14. Automated image registration for FDOPA PET studies

    International Nuclear Information System (INIS)

    Kang-Ping Lin; Sung-Cheng Huang, Dan-Chu Yu; Melega, W.; Barrio, J.R.; Phelps, M.E.

    1996-01-01

    In this study, various image registration methods are investigated for their suitability for registration of L-6-[18F]-fluoro-DOPA (FDOPA) PET images. Five different optimization criteria including sum of absolute difference (SAD), mean square difference (MSD), cross-correlation coefficient (CC), standard deviation of pixel ratio (SDPR), and stochastic sign change (SSC) were implemented and Powell's algorithm was used to optimize the criteria. The optimization criteria were calculated either unidirectionally (i.e. only evaluating the criteria for comparing the resliced image 1 with the original image 2) or bidirectionally (i.e. averaging the criteria for comparing the resliced image 1 with the original image 2 and those for the sliced image 2 with the original image 1). Monkey FDOPA images taken at various known orientations were used to evaluate the accuracy of different methods. A set of human FDOPA dynamic images was used to investigate the ability of the methods for correcting subject movement. It was found that a large improvement in performance resulted when bidirectional rather than unidirectional criteria were used. Overall, the SAD, MSD and SDPR methods were found to be comparable in performance and were suitable for registering FDOPA images. The MSD method gave more adequate results for frame-to-frame image registration for correcting subject movement during a dynamic FDOPA study. The utility of the registration method is further demonstrated by registering FDOPA images in monkeys before and after amphetamine injection to reveal more clearly the changes in spatial distribution of FDOPA due to the drug intervention. (author)

  15. A high-repetition rate LWFA for studies of laser propagation and electron generation

    Science.gov (United States)

    He, Zhaohan; Easter, James; Hou, Bixue; Krushelnick, Karl; Nees, John; Thomas, Alec

    2010-11-01

    Advances in ultrafast optics today have enabled laser systems to deliver ever shorter and more intense pulses. When focused, such laser pulses can easily exceed relativistic intensities where the wakefield created by the strong laser electric field can be used to accelerate electrons. Laser wakefield acceleration of electrons holds promise for future compact electron accelerators or drivers of other radiation sources in many scientific, medical and engineering applications. We present experimental studies of laser wakefield acceleration using the λ-cubed laser at the University of Michigan -- a table-top high-power laser system operating at 500 Hz repetition rate. The high repetition rate allows statistical studies of laser propagation and electron acceleration which are not accessible with typical sub-0.1 Hz repetition rate systems. In addition, we compare the experiments with particle-in-cell simulations using the code OSIRIS.

  16. Bulk and track etching of PET studied by spectrophotometer

    International Nuclear Information System (INIS)

    Zhu, Z.Y.; Duan, J.L.; Maekawa, Y.; Koshikawa, H.; Yoshida, M.

    2004-01-01

    UV-VIS spectra of poly(ethylene terephthalate) (PET) solutions formed by etching PET in NaOH solution were analyzed with respect to the etching time. A linear relationship between absorptions centered at 4.45 and 5.11 eV with weight loss of PET in NaOH solution was established. The relation was applied to study the influence of UV light illumination on bulk etching of PET and to evaluate pore size of etched-through tracks. It is found that bulk etching of PET can be greatly enhanced by UV illumination in air in the wavelength range around 313 nm. A surface area of about 350 nm in thickness shows a 23 times increase in bulk-etching rate after illuminated for 6 h. The phenomenon is attributed to the oxygen-assisted photo-degradation through generating of new photo-unstable species. The enhancement in bulk etching was immediately reduced as the etching proceeds below the surface with an exponential decay constant of about 1.5 μm -1 . Etching of Xe ion irradiated PET films gives extra etching products with similar chemical structure as revealed by spectrophotometer measurements. Quantitative analysis of etching products from latent tracks implies that pores of about 14.6 nm in radius are formed after etching in 0.74 N NaOH at 40 deg. C for 35 min, which is in agreement with the conductometric measurement

  17. Cortical activity and children's rituals, habits and other repetitive behavior: a visual P300 study.

    Science.gov (United States)

    Evans, David W; Maliken, Ashley

    2011-10-10

    This study examines the link between children's repetitive, ritualistic, behavior and cortical brain activity. Twelve typically developing children between the ages of 6 and 12 years were administered two visual P300, oddball tasks with a 32-electrode electroencephalogram (EEG) system. One of the oddball tasks was specifically designed to reflect sensitivity to asymmetry, a phenomenon common in children and in a variety of disorders involving compulsive behavior. Parents completed the Childhood Routines Inventory. Children's repetitive, compulsive-like behaviors were strongly associated with faster processing of an asymmetrical target stimulus, even when accounting for their P300 latencies on a control task. The research punctuates the continuity between observed brain-behavior links in clinical disorders such as OCD and autism spectrum disorders, and normative variants of repetitive behavior. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Simulation study comparing the helmet-chin PET with a cylindrical PET of the same number of detectors

    Science.gov (United States)

    Ahmed, Abdella M.; Tashima, Hideaki; Yoshida, Eiji; Nishikido, Fumihiko; Yamaya, Taiga

    2017-06-01

    There is a growing interest in developing brain PET scanners with high sensitivity and high spatial resolution for early diagnosis of neurodegenerative diseases and studies of brain functions. Sensitivity of the PET scanner can be improved by increasing the solid angle. However, conventional PET scanners are designed based on a cylindrical geometry, which may not be the most efficient design for brain imaging in terms of the balance between sensitivity and cost. We proposed a dedicated brain PET scanner based on a hemispheric shape detector and a chin detector (referred to as the helmet-chin PET), which is designed to maximize the solid angle by increasing the number of lines-of-response in the hemisphere. The parallax error, which PET scanners with a large solid angle tend to have, can be suppressed by the use of depth-of-interaction detectors. In this study, we carry out a realistic evaluation of the helmet-chin PET using Monte Carlo simulation based on the 4-layer GSO detector which consists of a 16  ×  16  ×  4 array of crystals with dimensions of 2.8  ×  2.8  ×  7.5 mm3. The purpose of this simulation is to show the gain in imaging performance of the helmet-chin PET compared with the cylindrical PET using the same number of detectors in each configuration. The sensitivity of the helmet-chin PET evaluated with a cylindrical phantom has a significant increase, especially at the top of the (field-of-view) FOV. The peak-NECR of the helmet-chin PET is 1.4 times higher compared to the cylindrical PET. The helmet-chin PET provides relatively low noise images throughout the FOV compared to the cylindrical PET which exhibits enhanced noise at the peripheral regions. The results show the helmet-chin PET can significantly improve the sensitivity and reduce the noise in the reconstructed images.

  19. Kinetic studies on a repetitively pulsed fast reactor

    International Nuclear Information System (INIS)

    Das, S.

    1982-01-01

    Neutronic analysis of an earlier proposed periodically pulsed fast reactor at Kalpakkam (KPFR) has been carried out numerically under equilibrium and transient conditions using the one-point model of reactor kinetics and the experimentally measured total worth of reactivity modulator, the parabolic coefficient of reactivity of the movable reflector and the mean prompt neutron lifetime. Results of steady-state calculations - treated on the basis of delayed neutron precursor and energy balances during a period of operation - have been compared with the analytical formulae of Larrimore for a parabolic reactivity input. Empirical relations for half-width of the fast neutron pulse, the peak pulse power and the power at first crossing of prompt criticality have been obtained and shown to be accurate enough for predicting steady-state power pulse characteristics of a periodically pulsed fast reactor. The concept of a subprompt-critical reactor has been used to calculate the fictitious delayed neutron fraction, β of the KPFR through a numerical experiment. Relative pulse height stability and pulse shape sensitivity to changes of maximum reactivity is discussed. With the aid of new safety concepts, the Power Amplification Factor (PAF) and the Pulse Growth Factor (Rsub(p)), the dynamics KPFR under accidental conditions has been studied for step and ramp reactivity perturbations. All the analysis has been done without taking account of reactivity feedback. (orig.)

  20. The PPET Study: people and pets exercising together.

    Science.gov (United States)

    Kushner, Robert F; Blatner, Dawn Jackson; Jewell, Dennis E; Rudloff, Kimberly

    2006-10-01

    Obesity is a significant public health problem that is affecting people and their pets. The human-companion animal bond and the role of pets in providing social support provides a rationale framework for studying the effectiveness of a combined people and pets (PP) exercising together (PPET) weight loss program. Thirty-six pairs of overweight or obese people with an obese pet (PP) and 56 overweight or obese people only (PO) participated in a 1-year prospective controlled weight loss study. In a group format, people received dietary and physical activity counseling, and dogs were fed a calorie-controlled prescription diet. Physical activity was recorded using the physical activity recall questionnaire. Completion rates at 1 year were 61% for the PP group and 58% for the PO group. Mean weight losses at 12 months using last observation carried forward were 4.7% (PP) and 5.2% (PO). Mean weight loss among the dogs was 15%. Time spent in physical activity increased in both groups to 3.9 (PP) and 3.5 (PO) h/wk. Two-thirds of total physical activity in the PP group was spent with the dogs. The PPET study is the first program to demonstrate the effectiveness of a combined PP weight loss program. This fresh approach to the dual obesity epidemic builds on the human-companion animal bond. Consideration of social support for weight loss of family members, friends, and coworkers should be extended to include pets.

  1. Study on cerebral activation areas during repetition with functional MRI in normal adults

    International Nuclear Information System (INIS)

    Koseki, Yohju

    2009-01-01

    For cerebral activation of speech areas in functional MRI (f-MRI) study, the usefulness of an optical microphone, which made it possible to perform task repetition at real time during scanning, was examined. Subjects were 25 healthy adults (mean age, 27.1±5.6 years), who consisted of 15 right-handed and 10 left-handed or ambidextrous persons. Tasks comprised repetition of monosyllables, non-words, words and sentences. The repetition tasks were covertly performed during scanning of f-MRI by using an optical microphone. In both the right-handed and non-right-handed groups, activations in the left superior temporal gyrus (sensory speech area) were most frequently observed during all of the tasks. In the right-handed group, activations in the left inferior frontal (motor speech area) and superior temporal gyri were significantly more often observed than those in the right inferior frontal and superior temporal gyri. From an assessment of the laterality index (LI), left-side dominant activation was frequently seen in most of the cerebral regions including sensory and motor speech areas, although right-side and bilateral dominant activations were observed in a few cases. In both groups, activations in regions associated with sensory speech were significantly more often seen than those in regions associated with motor speech. The present predominant activations in regions involved in sensory speech indicate that the optical microphone is useful in f-MRI studies using task repetition. (author)

  2. A phantom study of tumor contouring on PET imaging

    International Nuclear Information System (INIS)

    Chen Song; Li Xuena; Li Yaming; Yin Yafu; Li Na; Han Chunqi

    2010-01-01

    Objective: To explore an algorithm to define the threshold value for tumor contouring on 18 F-fluorodeoxyglucose (FDG) PET imaging. Methods: A National Electrical Manufacturing Association (NEMA)NU 2 1994 PET phantom with 5 spheres of different diameters were filled with 18 F-FDG. Seven different sphere-to-background ratios were obtained and the phantom was scanned by Discovery LS 4. For each sphere-to-background ratio, the maximum standardized uptake value (SUV max ) of each sphere, the SUV of the border of each sphere (SUV border ), the mean SUV of a 1 cm region of background (SUV bg ) and the diameter (D) of each sphere were measured. SPSS 13.0 software was used for curve fitting and regression analysis to obtain the threshold algorithm. The calculated thresholds were applied to delineate 29 pathologically confirmed lung cancer lesions on PET images and the obtained volumes were compared with the volumes contoured on CT images in lung window. Results: The algorithm for defining contour threshold is TH% = 33.1% + 46.8% SUV bg /SUV max + 13.9%/D (r = 0.994) by phantom studies. For 29 lung cancer lesions, the average gross tumor volumes (GTV) delineated on PET and CT are (7.36±1.62) ml and (8.31±2.05) ml, respectively (t = -1.26, P>0.05). Conclusion: The proposed threshold algorithm for tumor contouring on PET image could provide comparable GTV with CT. (authors)

  3. Serotonin synthesis studied with positron emission tomography, (PET)

    DEFF Research Database (Denmark)

    Honoré, Per Gustaf Hartvig; Lundquist, Pinelopi

    -L-(beta-11C tryptophan) (5HTP) quantifies the activity of amino acid decarboxylase in the conversion to 5HT. On the other hand, alpha-methyl-tryptophan (AMT) measures the conversion to the corresponding 5-hydroxytryptophan analogue. The irreversible binding of the PET probe 5HTP in the monkey brain was lower...... evaluations of neuroendocrine tumours. Though, a few studies using 5HT have been conducted on CNS disorders. AMT-PET studies have mainly been confined to brain diseases causing various degree of neurodegeneration....

  4. Counting repetitions: an observational study of video game play in people with chronic poststroke hemiparesis.

    Science.gov (United States)

    Peters, Denise M; McPherson, Aaron K; Fletcher, Blake; McClenaghan, Bruce A; Fritz, Stacy L

    2013-09-01

    The use of video gaming as a therapeutic intervention has increased in popularity; however, the number of repetitions in comparison with traditional therapy methods has yet to be investigated. The primary purpose of this study was to document and compare the number of repetitions performed while playing 1 of 2 video gaming systems for a time frame similar to that of a traditional therapy session in individuals with chronic stroke. Twelve participants with chronic stroke (mean age, 66.8 ± 8.2 years; time poststroke, 19.2 ± 15.4 months) completed video game play sessions, using either the Nintendo Wii or the Playstation 2 EyeToy. A total of 203 sessions were captured on video record; of these, 50 sessions for each gaming system were randomly selected for analysis. For each selected record, active upper and lower extremity repetitions were counted for a 36-minute segment of the recorded session. The Playstation 2 EyeToy group produced an average of 302.5 (228.1) upper extremity active movements and 189.3 (98.3) weight shifts, significantly higher than the Nintendo Wii group, which produced an average of 61.9 (65.7) upper extremity active movements and 109.7 (78.5) weight shifts. No significant differences were found in steps and other lower extremity active movements between the 2 systems. The Playstation 2 EyeToy group produced more upper extremity active movements and weight shifting movements than the Nintendo Wii group; the number and type of repetitions varied across games. Active gaming (specifically Playstation 2 EyeToy) provided more upper extremity repetitions than those reported in the literature by using traditional therapy, suggesting that it may be a modality to promote increased active movements in individuals poststroke.

  5. Optimization for PET imaging based on phantom study and NECdensity

    International Nuclear Information System (INIS)

    Daisaki, Hiromitsu; Shimada, Naoki; Shinohara, Hiroyuki

    2012-01-01

    In consideration of the requirement for global standardization and quality control of PET imaging, the present studies gave an outline of phantom study to decide both scan and reconstruction parameters based on FDG-PET/CT procedure guideline in Japan, and optimization of scan duration based on NEC density was performed continuously. In the phantom study, scan and reconstruction parameters were decided by visual assessment and physical indexes (N 10mm , NEC phantom , Q H,10mm /N 10mm ) to visualize hot spot of 10 mm diameter with standardized uptake value (SUV)=4 explicitly. Simultaneously, Recovery Coefficient (RC) was evaluated to recognize that PET images had enough quantifiably. Scan durations were optimized by Body Mass Index (BMI) based on retrospective analysis of NEC density . Correlation between visual score in clinical FDG-PET images and NEC density fell after the optimization of scan duration. Both Inter-institution and inter-patient variability were decreased by performing the phantom study based on the procedure guideline and the optimization of scan duration based on NEC density which seem finally useful to practice highly precise examination and promote high-quality controlled study. (author)

  6. PET/CT-guided interventional procedures: rationale, justification, initial study, and research plan

    Energy Technology Data Exchange (ETDEWEB)

    Wong, K.; Rahill, J.; Cleary, K. [Computer Aided Interventions and Medical Robotics (CAIMR), Imaging Science and Information Systems (ISIS) Center, Georgetown Univ. Medical Center, Washington, DC (United States); Petrillo, S.; Earl-Graef, D. [Dept. of Radiology, Georgetown Univ. Hospital, MedStar Health, Washington, DC (United States); Banovac, F.; Levy, E. [Computer Aided Interventions and Medical Robotics (CAIMR), Imaging Science and Information Systems (ISIS) Center, Georgetown Univ. Medical Center, Washington, DC (United States); Dept. of Radiology, Georgetown Univ. Hospital, MedStar Health, Washington, DC (United States); Shekhar, R. [Dept. of Radiology, Univ. of Maryland Medical Center, Baltimore, MD (United States)

    2007-06-15

    Positron-emission tomography (PET) and PET/CT (computed tomography) are becoming increasingly important for diagnosis and treatment of cancer. Clinically relevant changes can sometimes be seen on PET that are not seen on other imaging modalities. However, PET is not suitable for guiding biopsy as the images are not obtained in real-time. Therefore, our research group has begun developing a concept for PET/CT-guided interventional procedures. This paper presents the rationale for this concept, outlines our research plan, and includes an initial study to evaluate the relative sensitivity of CT and PET/CT in detecting suspicious lesions. (orig.)

  7. The effect of chemotherapy on rat brain PET: preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Su; Kim, Il Han; Yu, A Ram; Park, Ji Ae; Woo, Sang Keun; Kim, Jong Guk; Cheon, Gi Jeong; Kim, Byeong Il; Choi, Chang Woon; Lim, Sang Moo; Kim, Hee Joung; Kim, Kyeong Min [Korea Institute Radiological and Medical Science, Seoul (Korea, Republic of)

    2010-10-15

    Chemotherapy was widely used for the therapy of cancer patients. When chemotherapy was performed, transient cognitive memory problem was occurred. This cognitive problem in brain was called as chemobrain. In this study, we have developed rat model for chemobrain. Cerebral glucose metabolism after chemotherapy was assessed using animal PET and voxel based statistical analysis method

  8. The effect of chemotherapy on rat brain PET: preliminary study

    International Nuclear Information System (INIS)

    Kim, Jin Su; Kim, Il Han; Yu, A Ram; Park, Ji Ae; Woo, Sang Keun; Kim, Jong Guk; Cheon, Gi Jeong; Kim, Byeong Il; Choi, Chang Woon; Lim, Sang Moo; Kim, Hee Joung; Kim, Kyeong Min

    2010-01-01

    Chemotherapy was widely used for the therapy of cancer patients. When chemotherapy was performed, transient cognitive memory problem was occurred. This cognitive problem in brain was called as chemobrain. In this study, we have developed rat model for chemobrain. Cerebral glucose metabolism after chemotherapy was assessed using animal PET and voxel based statistical analysis method

  9. An optimization study of peak thermal neutron flux in moderators of advanced repetitive pulse reactors

    International Nuclear Information System (INIS)

    Asaoka, Takumi; Watanabe, N.

    1976-01-01

    In achieving a high peak thermal neutron flux in hydrogenous moderators installed in repetitive pulse reactors, the core-moderator arrangement can play as much an important role as the moderator design itself. However, the effect of the former has not been adequately emphasized to date, while a rather extensive study has been made on the latter. The present study concerns with a core-moderator system parameter optimization for a repetitive accelerator pulsed fast reactor. The results have shown that small differences in the arrangement resulting from the optimizations of various parameters are significant and the effects can be summed up to give an increase in the peak thermal flux by a factor of about two. (auth.)

  10. Studies of a Linac Driver for a High Repetition Rate X-Ray FEL

    International Nuclear Information System (INIS)

    Venturini, M.; Corlett, J.; Doolittle, L.; Filippetto, D.; Papadopoulos, C.; Penn, G.; Prosnitz, D.; Qiang, J.; Reinsch, M.; Ryne, R.; Sannibale, F.; Staples, J.; Wells, R.; Wurtele, J.; Zolotorev, M.; Zholents, A.

    2011-01-01

    We report on on-going studies of a superconducting CW linac driver intended to support a high repetition rate FEL operating in the soft x-rays spectrum. We present a pointdesign for a 1.8 GeV machine tuned for 300 pC bunches and delivering low-emittance, low-energy spread beams as needed for the SASE and seeded beamlines.

  11. Brain activation studies with PET and functional MRI

    Energy Technology Data Exchange (ETDEWEB)

    Yonekura, Yoshiharu [Fukui Medical Univ., Matsuoka (Japan). Biomedical Imaging Research Center; Sadato, Norihiro [Okazaki National Research Inst., Aichi (Japan). National Inst. for Physiological Sciences

    2002-01-01

    Application of PET and functional MRI in brain activation studies is reviewed. 3D-PET images obtained repeatedly after intravenous injection of about 370 MBq of H{sub 2}{sup 15}O can detect a faint blood flow change in the brain. Functional MRI can also detect the blood flow change in the brain due to blood oxygen level-dependent effect. Echo-planar imaging is popular in MRI with 1.5 or 3 T. Images are analyzed by statistical parametric mapping with correction of cerebral regions, anatomical normalization and statistics. PET data give the blood flow change by the H{sub 2}{sup 15}O incorporation into the brain and MRI data, by the scarce tissue oxygen consumption despite the change. Actual images during the cognition task-performance and of frequent artifacts are given. PET is suitable for studies of brain functions like sensibility and emotion and functional MRI, like cortex functions and clinical practices in identification of functional regions prior to surgery and evaluation of functional recovery of damaged brain. (K.H.)

  12. Brain activation studies with PET and functional MRI

    International Nuclear Information System (INIS)

    Yonekura, Yoshiharu; Sadato, Norihiro

    2002-01-01

    Application of PET and functional MRI in brain activation studies is reviewed. 3D-PET images obtained repeatedly after intravenous injection of about 370 MBq of H 2 15 O can detect a faint blood flow change in the brain. Functional MRI can also detect the blood flow change in the brain due to blood oxygen level-dependent effect. Echo-planar imaging is popular in MRI with 1.5 or 3 T. Images are analyzed by statistical parametric mapping with correction of cerebral regions, anatomical normalization and statistics. PET data give the blood flow change by the H 2 15 O incorporation into the brain and MRI data, by the scarce tissue oxygen consumption despite the change. Actual images during the cognition task-performance and of frequent artifacts are given. PET is suitable for studies of brain functions like sensibility and emotion and functional MRI, like cortex functions and clinical practices in identification of functional regions prior to surgery and evaluation of functional recovery of damaged brain. (K.H.)

  13. Investigations on the effects of ''Ecstasy'' on cerebral glucose metabolism: an 18-FDG PET study

    International Nuclear Information System (INIS)

    Schreckenberger, M.; Sabri, O.; Arning, C.; Tuttass, T.; Schulz, G.; Kaiser, H.J.; Wagenknecht, G.; Buell, U.; Gouzoulis-Mayfrank, E.; Sass, H.

    1998-01-01

    Purpose: The aim of the present study was to determine the acute effects of the 'Ecstasy' analogue MDE (3,4-methylendioxyethamphetamine) on the cerebral glucose metabolism (rMRGlu) of healthy volunteers. Method: In a randomised double-blind trial, 16 healthy volunteers without a history of drug abuse were examined with 18-FDG PET 110-120 minutes after oral administration of 2 mg/kg MDE (n=8) or placebo (n=8). Beginning two minutes prior to radiotracer injection, a constant cognitive stimulation was maintained for 32 minutes using a word repetition paradigm in order to ensure constant and comparable mental conditions during cerebral 18-FDG uptake. Individual brain anatomy was represented using T1-weighted 3D flash MRI, followed by manual regionalisation into 108 regions-of-interest and PET/MRI overlay. Absolute quantification of rMRGlu and comparison of glucose metabolism under MDE versus placebo were performed using Mann-Whitney U-test. Results: Absolute global MRGlu was not significantly changed under MDE versus placebo (MDE: 41,8±11,1 μmol/min/100 g, placebo: 50,1±18,1 μmol/min/100 g, p=0,298). The normalised regional metabolic data showed a significantly decreased rMRGlu in the bilateral frontal cortex: Left frontal posterior (-7.1%, p [de

  14. Echolalia or functional repetition in conversation--a case study of an individual with Huntington's disease.

    Science.gov (United States)

    Saldert, Charlotta; Hartelius, Lena

    2011-01-01

    In this case study, we investigated the use of repetition in an individual with a neurogenic communication disorder. We present an analysis of interaction in natural conversations between a woman with advanced Huntington's disease (HD), whose speech had been described as sometimes characterised by echolalia, and her personal assistant. The conversational interaction is analysed on a sequential level, and recurrent patterns are explored. Although the ability of the person with HD to interact is affected by chorea, word retrieval problems and reduced comprehension, she takes an active part in conversation. The conversational partner's contributions are often adapted to her communicative ability as they are formulated as questions or suggestions that can be elaborated on or responded to with a simple 'yes' or 'no'. The person with HD often repeats the words of her conversational partner in a way that extends her contributions and shows listenership, and this use of repetition is also frequent in ordinary conversations between non-brain-damaged individuals. The results show that the conversation partners in this case cooperate in making the conversation proceed and evolve, and that verbal repetition is used in a way that works as a strategy for compensating for the impairment.

  15. Towards Implementing an MR-based PET Attenuation Correction Method for Neurological Studies on the MR-PET Brain Prototype

    Science.gov (United States)

    Catana, Ciprian; van der Kouwe, Andre; Benner, Thomas; Michel, Christian J.; Hamm, Michael; Fenchel, Matthias; Fischl, Bruce; Rosen, Bruce; Schmand, Matthias; Sorensen, A. Gregory

    2013-01-01

    A number of factors have to be considered for implementing an accurate attenuation correction (AC) in a combined MR-PET scanner. In this work, some of these challenges were investigated and an AC method based entirely on the MR data obtained with a single dedicated sequence was developed and used for neurological studies performed with the MR-PET human brain scanner prototype. Methods The focus was on the bone/air segmentation problem, the bone linear attenuation coefficient selection and the RF coil positioning. The impact of these factors on the PET data quantification was studied in simulations and experimental measurements performed on the combined MR-PET scanner. A novel dual-echo ultra-short echo time (DUTE) MR sequence was proposed for head imaging. Simultaneous MR-PET data were acquired and the PET images reconstructed using the proposed MR-DUTE-based AC method were compared with the PET images reconstructed using a CT-based AC. Results Our data suggest that incorrectly accounting for the bone tissue attenuation can lead to large underestimations (>20%) of the radiotracer concentration in the cortex. Assigning a linear attenuation coefficient of 0.143 or 0.151 cm−1 to bone tissue appears to give the best trade-off between bias and variability in the resulting images. Not identifying the internal air cavities introduces large overestimations (>20%) in adjacent structures. Based on these results, the segmented CT AC method was established as the “silver standard” for the segmented MR-based AC method. Particular to an integrated MR-PET scanner, ignoring the RF coil attenuation can cause large underestimations (i.e. up to 50%) in the reconstructed images. Furthermore, the coil location in the PET field of view has to be accurately known. Good quality bone/air segmentation can be performed using the DUTE data. The PET images obtained using the MR-DUTE- and CT-based AC methods compare favorably in most of the brain structures. Conclusion An MR-DUTE-based AC

  16. Multi institutional quantitative phantom study of yttrium-90 PET in PET/MRI: the MR-QUEST study.

    Science.gov (United States)

    Maughan, Nichole M; Eldib, Mootaz; Faul, David; Conti, Maurizio; Elschot, Mattijs; Knešaurek, Karin; Leek, Francesca; Townsend, David; DiFilippo, Frank P; Jackson, Kimberly; Nekolla, Stephan G; Lukas, Mathias; Tapner, Michael; Parikh, Parag J; Laforest, Richard

    2018-04-04

    Yttrium-90 ( 90 Y) radioembolization involves the intra-arterial delivery of radioactive microspheres to treat hepatic malignancies. Though this therapy involves careful pre-treatment planning and imaging, little is known about the precise location of the microspheres once they are administered. Recently, there has been growing interest post-radioembolization imaging using positron-emission tomography (PET) for quantitative dosimetry and identifying lesions that may benefit from additional salvage therapy. In this study, we aim to measure the inter-center variability of 90 Y PET measurements as measured on PET/MRI in preparation for a multi-institutional prospective phase I/II clinical trial. Eight institutions participated in this study and followed a standardized phantom filling and imaging protocol. The NEMA NU2-2012 body phantom was filled with 3 GBq of 90 Y chloride solution. The phantom was imaged for 30 min in listmode on a Siemens Biograph mMR non-TOF PET/MRI scanner at five time points across 10 days (0.3-3.0 GBq). Raw PET data were sent to a central site for image reconstruction and data analysis. Images were reconstructed with optimal parameters determined from a previous study. Volumes of interest (VOIs) matching the known sphere diameters were drawn on the vendor-provided attenuation map and propagated to the PET images. Recovery coefficients (RCs) and coefficient of variation of the RCs (COV) were calculated from these VOIs for each sphere size and activity level. Mean RCs ranged from 14.5 to 75.4%, with the lowest mean RC coming from the smallest sphere (10 mm) on the last day of imaging (0.16 MBq/ml) and the highest mean RC coming from the largest sphere (37 mm) on the first day of imaging (2.16 MBq/ml). The smaller spheres tended to exhibit higher COVs. In contrast, the larger spheres tended to exhibit lower COVs. COVs from the 37 mm sphere were  25%. Post-radioembolization dosimetry of lesions or other VOIs ≥ 22 mm in diameter can

  17. The Move from Accuracy Studies to Randomized Trials in PET

    DEFF Research Database (Denmark)

    Siepe, Bettina; Hoilund-Carlsen, Poul Flemming; Gerke, Oke

    2014-01-01

    an important role in informing guideline developers and policy makers. Our aim was to investigate how far the nuclear medicine community has come on its way from accuracy studies to RCTs and which issues we have to take into account in planning future studies. METHODS: We conducted a systematic review...... evaluation. Choice of patient-important outcomes and sufficient sample sizes are crucial issues in planning RCTs to demonstrate the clinical benefit of using PET....

  18. In vivo study of central receptors in man using pet

    International Nuclear Information System (INIS)

    Baron, J.C.

    1986-09-01

    Central neurotransmitter systems and receptors are intimately involved in the mechanism of several neurologic and phychiatric disorders. Although neurotransmitter concentration and receptor function can be measured regionnally post-mortem, studies performed during life may provide insight into changes at early stages of the disease as well as follow-up data on, and pharmacological modification of, such changes. Positron Tomography (PET) allows to monitor non-invasively the time-course of regional tissue tracer concentration following administration of a radioactive drug. If the latter is known to interact selectively with specific binding sites, it can be used to probe in vivo the regional distribution and affinity of the receptors involved. As shown in this progress report, several receptor systems can now be studied reliably in humans, using PET

  19. Pet ownership and risk of asthma: a case-controlled study

    Directory of Open Access Journals (Sweden)

    Sharifi

    2008-08-01

    Full Text Available Background: In the treatment of bronchial asthma, the identification, isolation, and elimination of causative allergens is the most effective part of treatment. With the recent diversification within the pet industry, pet owner exposure to many unknown antigens is on the rise. The results of population studies have been contradictory and some epidemiological studies have failed to confirm this, some indicating that keeping pets might actually reduce the risk of sensitization and asthma. The purpose of this study was to determine the association between pet ownership and asthma. Methods: This case-control study included 300 asthmatic participants referred to the Children's Medical Center over a two-year period. Participants were asked to fill out a questionnaire regarding pet ownership, pet gender and puberty, the place it was kept, how long the pet was kept and the reason for keeping the pet. The same questions were asked from 300 age- and gender-matched nonasthmatic individuals as the control group. Statistical analysis was performed to calculate odds ratios (OR of asthma morbidity in individuals who kept pets. Results: The OR for asthma morbidity in patients who kept pets was 2.59 (CI=1.60-4.21 and p>0.001. Financial aim was the most common reason for keeping a pet and most pets were mature and kept outdoors. No significant correlations for pet genders were observed. Conclusion: This survey provides evidence that pet ownership is an important risk factor for asthma, therefore we suggest that individuals at risk for asthma (atopic individuals must avoid contact with pets. However, more research in this field in Iran is necessary.

  20. Problem-solving ability and repetition of deliberate self-harm: a multicentre study.

    Science.gov (United States)

    McAuliffe, Carmel; Corcoran, Paul; Keeley, Helen S; Arensman, Ella; Bille-Brahe, Unni; De Leo, Diego; Fekete, Sandor; Hawton, Keith; Hjelmeland, Heidi; Kelleher, Margaret; Kerkhof, Ad J F M; Lönnqvist, Jouko; Michel, Konrad; Salander-Renberg, Ellinor; Schmidtke, Armin; Van Heeringen, Kees; Wasserman, Danuta

    2006-01-01

    While recent studies have found problem-solving impairments in individuals who engage in deliberate self-harm (DSH), few studies have examined repeaters and non-repeaters separately. The aim of the present study was to investigate whether specific types of problem-solving are associated with repeated DSH. As part of the WHO/EURO Multicentre Study on Suicidal Behaviour, 836 medically treated DSH patients (59% repeaters) from 12 European regions were interviewed using the European Parasuicide Study Interview Schedule (EPSIS II) approximately 1 year after their index episode. The Utrecht Coping List (UCL) assessed habitual responses to problems. Factor analysis identified five dimensions--Active Handling, Passive-Avoidance, Problem Sharing, Palliative Reactions and Negative Expression. Passive-Avoidance--characterized by a pre-occupation with problems, feeling unable to do anything, worrying about the past and taking a gloomy view of the situation, a greater likelihood of giving in so as to avoid difficult situations, the tendency to resign oneself to the situation, and to try to avoid problems--was the problem-solving dimension most strongly associated with repetition, although this association was attenuated by self-esteem. The outcomes of the study indicate that treatments for DSH patients with repeated episodes should include problem-solving interventions. The observed passivity and avoidance of problems (coupled with low self-esteem) associated with repetition suggests that intensive therapeutic input and follow-up are required for those with repeated DSH.

  1. Study of pulse shapes in Ge detectors with PET

    Energy Technology Data Exchange (ETDEWEB)

    Grabmayr, Peter; Hegai, Alexander; Jochum, Josef; Schmitt, Christopher; Schuetz, Ann-Kathrin [Eberhard Karls Univeritaet Tuebingen (Germany); Collaboration: GERDA-Collaboration

    2016-07-01

    The Gerda collaboration aims to determine the half life of the neutrinoless double beta decay (0νββ) of {sup 76}Ge. For Phase II Gerda wants to reduce the background contribution significantly by active background-suppression techniques. One of such techniques is the pulse shape analysis of signals induced by the interaction of radiation with the detector. The pulse shapes depend not only on the energy of the interacting gamma, the geometry and field configuration but also on the location of interaction in the crystal. The waveform and the location of the interaction in the germanium can be determined by positron-emission-tomography (PET). First results of this novel pulse shape study with the PET will be presented in this talk.

  2. SEP-225289 serotonin and dopamine transporter occupancy: a PET study.

    Science.gov (United States)

    DeLorenzo, Christine; Lichenstein, Sarah; Schaefer, Karen; Dunn, Judith; Marshall, Randall; Organisak, Lisa; Kharidia, Jahnavi; Robertson, Brigitte; Mann, J John; Parsey, Ramin V

    2011-07-01

    SEP-225289 is a novel compound that, based on in vitro potencies for transporter function, potentially inhibits reuptake at dopamine, norepinephrine, and serotonin transporters. An open-label PET study was conducted during the development of SEP-225289 to investigate its dopamine and serotonin transporter occupancy. Different single doses of SEP-225289 were administered to healthy volunteers in 3 cohorts: 8 mg (n = 7), 12 mg (n = 5), and 16 mg (n = 7). PET was performed before and approximately 24 h after oral administration of SEP-225289, to assess occupancy at trough levels. Dopamine and serotonin transporter occupancies were estimated from PET using (11)C-N-(3-iodoprop-2E-enyl)-2β-carbomethoxy-3β-(4-methylphenyl)nortropane ((11)C-PE2I) and (11)C-N,N-dimethyl-2-(2-amino-4-cyanophenylthio)benzylamine ((11)C-DASB), respectively. Plasma concentration of SEP-225289 was assessed before ligand injection, and subjects were monitored for adverse events. Average dopamine and serotonin transporter occupancies increased with increasing doses of SEP-225289. Mean dopamine and serotonin transporter occupancies were 33% ± 11% and 2% ± 13%, respectively, for 8 mg; 44% ± 4% and 9% ± 10%, respectively, for 12 mg; and 49% ± 7% and 14% ± 15%, respectively, for 16 mg. On the basis of the relationship between occupancy and plasma concentration, dopamine transporter IC(50) (the plasma concentration of drug at 50% occupancy) was determined (4.5 ng/mL) and maximum dopamine transporter occupancy was extrapolated (85%); however, low serotonin transporter occupancy prevented similar serotonin transporter calculations. No serious adverse events were reported. At the doses evaluated, occupancy of the dopamine transporter was significantly higher than that of the serotonin transporter, despite similar in vitro potencies, confirming that, in addition to in vitro assays, PET occupancy studies can be instrumental to the drug development process by informing early decisions about

  3. Temporal lobe dysfunction in childhood autism: a PET study

    International Nuclear Information System (INIS)

    Boddaert, N.; Poline, J.B.; Brunelle, F.; Zilbovicius, M.; Boddaert, N.; Brunelle, F.; Chabane, N.; Barthelemy, C.; Zilbovicius, M.; Bourgeois, M.; Samson, Y.

    2002-01-01

    Childhood autism is a severe developmental disorder that impairs the acquisition of some of the most important skills in human life. Progress in understanding the neural basis of childhood autism requires clear and reliable data indicating specific neuro-anatomical or neuro-physiological abnormalities. The purpose of the present study was to research localized brain dysfunction in autistic children using functional brain imaging. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) in 21 primary autistic children and 10 age-matched non autistic children. A statistical parametric analysis of rCBF images revealed significant bilateral temporal hypoperfusion in the associative auditory cortex (superior temporal gyrus) and in the multimodal cortex (superior temporal sulcus) in the autistic group (p<0.001). In addition, temporal hypoperfusion was detected individually in 77% of autistic children. These findings provide robust evidence of well localized functional abnormalities in autistic children located in the superior temporal lobe. Such localized abnormalities were not detected with the low resolution PET camera (14-22). This study suggests that high resolution PET camera combined with statistical parametric mapping is useful to understand developmental disorders. (authors)

  4. The clinical impact of PET scanning in patients with melanoma: A prospective study

    International Nuclear Information System (INIS)

    Kalff, V.; Hicks, R.J.; Binns, D.S.; Henderson, M.A.; Ainslie, J.; Jenner, D.A.

    1998-01-01

    Full text: Small series have shown that PET scanning using F-18 fluorodeoxyglucose (FDG), can quite accurately stage patients melanoma. At this Institute these patients are only sent for PET imaging if they have high risk melanomas ( >3 Clarke's grade primaries) or there remains any significant doubt as to their clinical staging or management after the completion of conventional screening. This prospective study examines how PET scan findings influenced the clinical management decisions in 53 patients (29 males, mean age 54±13 yrs: range 31-81 yrs) Referring doctors were asked to indicate reason for the PET scan, stage their patients on the basis of all their current investigations, and to indicate their management plans prior to PET scanning. Follow-up of subsequent patient management at 2-4 weeks post PET scan was then obtained and compared to pre PET plans. PET was used to stage 26 patients, restage 17, follow-up 5, assess recurrence in 3, and other in 2 patients. To date follow-up has shown that in 32/49 (65%) patients PET was used to triage patients to locoregional surgery (10 patients), radical radiotherapy (5 patients), or to continuing follow-up only (17 patients). Three further high risk patients with negative PET scans had sentinel mode biopsy. In only 13 patients was management already determined, with planned treatment being changed in 6. Four patients have not had their post PET scan review yet. To date proven false negative PET scans have occurred in 3 cases, 2 sentinel node biopsies showed microscopic disease, and one scan incorrectly labelled gall-bladder melanoma as hydro-nephrotic kidney. Interestingly in 3 cases, PET discovered other unsuspected tumours (rectum x 2, plasmacytoma). PET scanning has been incorporated into routine management to triage most high risk patients, but it still alters interventions in half of those patients where management has already been planned. PET clearly misses small volume disease, the importance of which is

  5. Risk factors for repetition of self-harm: a systematic review of prospective hospital-based studies.

    Directory of Open Access Journals (Sweden)

    Celine Larkin

    Full Text Available BACKGROUND: Self-harm entails high costs to individuals and society in terms of suicide risk, morbidity and healthcare expenditure. Repetition of self-harm confers yet higher risk of suicide and risk assessment of self-harm patients forms a key component of the health care management of self-harm patients. To date, there has been no systematic review published which synthesises the extensive evidence on risk factors for repetition. OBJECTIVE: This review is intended to identify risk factors for prospective repetition of self-harm after an index self-harm presentation, irrespective of suicidal intent. DATA SOURCES: PubMed, PsychInfo and Scirus were used to search for relevant publications. We included cohort studies which examining factors associated with prospective repetition among those presenting with self-harm to emergency departments. Journal articles, abstracts, letters and theses in any language published up to June 2012 were considered. Studies were quality-assessed and synthesised in narrative form. RESULTS: A total of 129 studies, including 329,001 participants, met our inclusion criteria. Some factors were studied extensively and were found to have a consistent association with repetition. These included previous self-harm, personality disorder, hopelessness, history of psychiatric treatment, schizophrenia, alcohol abuse/dependence, drug abuse/dependence, and living alone. However, the sensitivity values of these measures varied greatly across studies. Psychological risk factors and protective factors have been relatively under-researched but show emerging associations with repetition. Composite risk scales tended to have high sensitivity but poor specificity. CONCLUSIONS: Many risk factors for repetition of self-harm match risk factors for initiation of self-harm, but the most consistent evidence for increased risk of repetition comes from long-standing psychosocial vulnerabilities, rather than characteristics of an index episode

  6. The effect of posture and repetition on urodynamic parameters: A prospective randomized study

    Directory of Open Access Journals (Sweden)

    Ho Joon Jeon

    2017-01-01

    Full Text Available Purpose: To evaluate the effect of posture and repetition of filling cystometry on urodynamic parameters. Materials and Methods: Seventy-one men with benign prostatic hyperplasia participated in a urodynamic study between September 2015 and August 2016 and were randomly assigned to a supine to supine (group SS, n=16, erect to erect (group EE, n=16, supine to erect (group SE, n=19 or erect to supine (group ES, n=20 group. The patients underwent filling cystometry twice. We evaluated the effect of posture and the effect of repetition on filling cystometric parameters. We also evaluated the correlation between overactive bladder (OAB and detrusor overactivity (DO and between maximum voided volume (MVV and maximum cystometric capacity (MCC for each posture and filling cystometry time. Results: There was a decrease in bladder sensation and occurrence of DO, and an increase in bladder compliance and MCC in the supine posture group compared to that in the erect posture group. A more significant decrease in bladder sensation and occurrence of DO as well as an increase in MCC was seen during the second filling cystometry than the first one. The supine posture during first filling cystometry showed a better correlation between OAB and DO and between MVV and MCC than erect posture. Conclusions: There were clear effects of posture and filling cystometry repetition on urodynamic parameters. The supine posture and repeated filling cystometry caused the bladder to be less sensitive and less overactive. The supine posture showed a better correlation to OAB symptoms than erect posture during first filling cystometry.

  7. A Study on Mental Health Status and Personality Traits of Pet Owners

    Directory of Open Access Journals (Sweden)

    H Choobineh

    2007-07-01

    Full Text Available Introduction & Objective: Many Iranian families manage to keep pets at home. Examining psychological consequences and personality traits of pet owners is important. The aim of this study was to examine mental health status and personality traits of pet owners. Materials & Methods: In this descriptive study, 612 pet owners (143 cat owners, 162 dog owners, 155 bird owners and 152 other pet owners were asked to complete General Health Questionnaire (GHQ and IPIP Personality Scale from January to December 2006. Results: Bird owners had the highest (234 cases (38.3% and other pet owners had the lowest (129 cases (42.3% mental health problems. In general, 188 cases (30.7% of all groups had mental health problems. 122 cases (20% of them had somatic compliance, 182 cases (29.7% had anxiety, 149 cases (24.3% had social dysfunction and 84 cases (13.7% had depression. Bird owners had significant high level of social dysfunction than other pet owners. With respect to personality traits, dog owners had low level of agreeableness and openness to experience than other groups. Other pet owners had high level of emotional stability than other groups. Conclusion: Contrary to other countries, it seems that having a pet in home enhances the probability of mental disorders in Iran. It is possible that lower mental health persons were keeping pets in Iran. In personality perspectives, dog owners are more disagreeable people and other pet owners are more emotionally stable ones.

  8. Imaging large vessel vasculitis with fully integrated PET/MRI: a pilot study

    International Nuclear Information System (INIS)

    Einspieler, Ingo; Pyka, Thomas; Eiber, Matthias; Thuermel, Klaus; Wolfram, Sabine; Moog, Philipp; Reeps, Christian; Essler, Markus

    2015-01-01

    The aim of this study was to evaluate the feasibility of hybrid [ 18 F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/MRI in patients with large vessel vasculitis (LVV) by comparing visual and quantitative parameters to that of PET/CT. Furthermore, the value of PET/MRI in disease activity and extent of LVV was assessed. A total of 16 [ 18 F]FDG PET/MRI and 12 [ 18 F]-FDG PET/CT examinations were performed in 12 patients with LVV. MRI of the vessel wall by T1-weighted and T2-weighted sequences was used for anatomical localization of FDG uptake and identification of morphological changes associated with LVV. In addition, contrast-enhanced (CE) magnetic resonance angiography (MRA) was performed. The vascular FDG uptake in the vasculitis group was compared to a reference group of 16 patients using a four-point visual score. Visual scores and quantitative parameters [maximum standardized uptake value (SUV max ) and target to background ratio (TBR)] were compared between PET/MRI and PET/CT. Furthermore, correlations between C-reactive protein (CRP) and quantitative PET results, as well the extent of vasculitis in PET, MRI/CE-MRA and combined PET/MRI, were analysed. TBRs, SUV max values and visual scores correlated well between PET/MRI and PET/CT (r = 0.92, r = 0.91; r = 0.84, p < 0.05). There was no significant difference between both modalities concerning SUV max measurements and visual scores. In PET/MRI, PET alone revealed abnormal FDG uptake in 86 vascular regions. MRI/CE-MRA indicated 49 vessel segments with morphological changes related to vasculitis, leading to a total number of 95 vasculitis regions in combination with PET. Strong and significant correlations between CRP and disease extent in PET alone (r = 0.75, p = 0.0067) and PET/MRI (r = 0.92, p < 0.0001) in contrast to MRI/CE-MRA only were observed. Regarding disease activity, no significant correlations were seen between quantitative PET results and CRP, although there was a trend towards

  9. Imaging large vessel vasculitis with fully integrated PET/MRI: a pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Einspieler, Ingo; Pyka, Thomas; Eiber, Matthias [Technische Universitaet Muenchen, Klinikum rechts der Isar, Department of Nuclear Medicine, Munich (Germany); Thuermel, Klaus; Wolfram, Sabine; Moog, Philipp [Technische Universitaet Muenchen, Klinikum rechts der Isar, Department of Nephrology, Munich (Germany); Reeps, Christian [Technische Universitaet Muenchen, Department of Vascular Surgery, Klinikum rechts der Isar, Munich (Germany); Essler, Markus [Rheinische Friedrich-Wilhelms-Universitaet, Department of Nuclear Medicine, Universitaetsklinikum Bonn, Bonn (Germany)

    2015-04-16

    The aim of this study was to evaluate the feasibility of hybrid [{sup 18}F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/MRI in patients with large vessel vasculitis (LVV) by comparing visual and quantitative parameters to that of PET/CT. Furthermore, the value of PET/MRI in disease activity and extent of LVV was assessed. A total of 16 [{sup 18}F]FDG PET/MRI and 12 [{sup 18}F]-FDG PET/CT examinations were performed in 12 patients with LVV. MRI of the vessel wall by T1-weighted and T2-weighted sequences was used for anatomical localization of FDG uptake and identification of morphological changes associated with LVV. In addition, contrast-enhanced (CE) magnetic resonance angiography (MRA) was performed. The vascular FDG uptake in the vasculitis group was compared to a reference group of 16 patients using a four-point visual score. Visual scores and quantitative parameters [maximum standardized uptake value (SUV{sub max}) and target to background ratio (TBR)] were compared between PET/MRI and PET/CT. Furthermore, correlations between C-reactive protein (CRP) and quantitative PET results, as well the extent of vasculitis in PET, MRI/CE-MRA and combined PET/MRI, were analysed. TBRs, SUV{sub max} values and visual scores correlated well between PET/MRI and PET/CT (r = 0.92, r = 0.91; r = 0.84, p < 0.05). There was no significant difference between both modalities concerning SUV{sub max} measurements and visual scores. In PET/MRI, PET alone revealed abnormal FDG uptake in 86 vascular regions. MRI/CE-MRA indicated 49 vessel segments with morphological changes related to vasculitis, leading to a total number of 95 vasculitis regions in combination with PET. Strong and significant correlations between CRP and disease extent in PET alone (r = 0.75, p = 0.0067) and PET/MRI (r = 0.92, p < 0.0001) in contrast to MRI/CE-MRA only were observed. Regarding disease activity, no significant correlations were seen between quantitative PET results and CRP, although there

  10. Roles of repetitive sequences

    Energy Technology Data Exchange (ETDEWEB)

    Bell, G.I.

    1991-12-31

    The DNA of higher eukaryotes contains many repetitive sequences. The study of repetitive sequences is important, not only because many have important biological function, but also because they provide information on genome organization, evolution and dynamics. In this paper, I will first discuss some generic effects that repetitive sequences will have upon genome dynamics and evolution. In particular, it will be shown that repetitive sequences foster recombination among, and turnover of, the elements of a genome. I will then consider some examples of repetitive sequences, notably minisatellite sequences and telomere sequences as examples of tandem repeats, without and with respectively known function, and Alu sequences as an example of interspersed repeats. Some other examples will also be considered in less detail.

  11. Usefulness of Integrated PET/MRI in Head and Neck Cancer: A Preliminary Study

    International Nuclear Information System (INIS)

    Lee, Soo Jin; Seo, Hyo Jung; Cheon, Gi Jeong; Kim, Ji Hoon; Kim, E. Edmund; Kang, Keon Wook; Paeng, Jin Chul; Chung, Junekey; Lee, Dong Soo

    2014-01-01

    The new modality of an integrated positron emission tomography/magnetic resonance imaging (PET/MRI) has recently been introduced but not validated. Our objective was to evaluate clinical performance of 18 F-fluoro-2-deoxyglucose ( 18 F-FDG) PET/MRI in patients with head and neck cancer. This retrospective study was conducted between January 2013 and February 2013. Ten patients (eight men, two women; mean age, 61.4±13.4 years) with histologically proven head and neck tumors were enrolled.Whole-body PET/MRI and regional positron emission tomography (PET) with dedicated MRI were sequentially obtained. Maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume, total lesion glycolysis and contrast enhancement were analyzed. A total of ten whole-body positron emission tomography (PET), ten regional positron emission tomography (PET), ten dedicated MRI and ten regional PET/gadolinium-enhanced T1-weighted (Gd)-MRI images were analyzed for initial staging. Two nuclear medicine physicians analyzed positron emission tomography (PET) and PET/MRI with a consensus. One radiologist analyzed dedicated MRI. The primary lesions and number of metastatic lymph nodes analyzed from each image were compared. Eight patients were diagnosed with head and neck cancer (one tongue cancer, four tonsillar cancers, one nasopharyngeal cancer and two hypopharyngeal cancers) by histological diagnosis. Two benign tumors (pleomorphic adenoma and Warthin tumor) were diagnosed with surgical operation. Whole-body positron emission tomography (PET) and regional positron emission tomography (PET) attenuated by MRI showed good image quality for the lesion detection. Whole-body positron emission tomography (PET) and regional positron emission tomography (PET) detected ten primary sites and compensated for a missed lesion on dedicated MRI. A discordant number of suspicious lymph node metastases was noted according to the different images; 22, 16, 39 and 40 in the whole-body positron

  12. Understanding the context for pet cat and dog feeding and exercising behaviour among pet owners in Ireland: a qualitative study

    OpenAIRE

    Downes, Martin J.; Devitt, Catherine; Downes, Marie T.; More, Simon J.

    2017-01-01

    Background Pet cat and dog obesity contributes to increased risk of several diseases, including cancer and diabetes mellitus as well as a worsening of orthopaedic problems, and a reduction in survival rate. This study aims to develop a better understanding of cat and dog owners’ self-reported beliefs and factors that influence owner behaviour around feeding and exercising their pet cat or dog, as there is a lack of in-depth understanding in this area. Seven focus group discussions, with 43 pe...

  13. Effect of low frequency rTMS stimulation over lateral cerebellum: a FDG PET study

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Eun Jin; Cho, Sang Soo; Bang, Soong Ae; Park, Hyun Soo; Kim, Sang Eun [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    2007-07-01

    Several lines of evidence suggested the involvement of cerebellum in cognitive function as well as motor function. Because of the measurement difficulty of functional connectivity, little is known about the underlying mechanism involvement of cerebellum in motor and cognitive function in living human brain. To understand the role of cerebellum within the neural network, we investigated the changes of neuronal activity elicited by the cerebellar repetitive transcranial magnetic stimulation (rTMS). 11 right-handed normal volunteers (age: 23.4{+-}2.5 y;6 males) were studied with FDG PET under two conditions; sham and 1Hz rTMS over left lateral cerebellum. With 10 min inter-block interval, three blocks of rTMS were started with the intravenous injection of [18F]FDG. In each block, 5min rTMS were delivered with an intensity of 90% of the resting motor threshold (RMT). Sham rTMS was delivered with same protocol but the coil was positioned perpendicular to the target area with 50% RMT. PET scans were acquired immediately after the rTMS stimulation. Sham and 1Hz rTMS images compared using paired t-test with SPM2. Inhibited neuronal activity compare to the sham condition were revealed in the stimulated left lateral cerebellum and orbitofrontal gyrus and right motor related areas (S1, SMA and posterior parietal cortex). While enhanced neuronal activity compare to the sham condition were revealed in the bilateral inferior frontal gyri including Broca's area and superior temporal gyrus including primary auditory cortex. Bilateral middle temporal, left precentral and right middle occipital gyri were also showed enhanced neuronal activity. This result showed that rTMS over left lateral cerebellum modulate direct vicinity of the targeted region and a large network of remote interconnected contralateral motor and ipsilateral language related brain regions. Present result provide evidence that cerebellum may contribute to language related cognitive function as well as motor

  14. Effect of low frequency rTMS stimulation over lateral cerebellum: a FDG PET study

    International Nuclear Information System (INIS)

    Yoon, Eun Jin; Cho, Sang Soo; Bang, Soong Ae; Park, Hyun Soo; Kim, Sang Eun

    2007-01-01

    Several lines of evidence suggested the involvement of cerebellum in cognitive function as well as motor function. Because of the measurement difficulty of functional connectivity, little is known about the underlying mechanism involvement of cerebellum in motor and cognitive function in living human brain. To understand the role of cerebellum within the neural network, we investigated the changes of neuronal activity elicited by the cerebellar repetitive transcranial magnetic stimulation (rTMS). 11 right-handed normal volunteers (age: 23.4±2.5 y;6 males) were studied with FDG PET under two conditions; sham and 1Hz rTMS over left lateral cerebellum. With 10 min inter-block interval, three blocks of rTMS were started with the intravenous injection of [18F]FDG. In each block, 5min rTMS were delivered with an intensity of 90% of the resting motor threshold (RMT). Sham rTMS was delivered with same protocol but the coil was positioned perpendicular to the target area with 50% RMT. PET scans were acquired immediately after the rTMS stimulation. Sham and 1Hz rTMS images compared using paired t-test with SPM2. Inhibited neuronal activity compare to the sham condition were revealed in the stimulated left lateral cerebellum and orbitofrontal gyrus and right motor related areas (S1, SMA and posterior parietal cortex). While enhanced neuronal activity compare to the sham condition were revealed in the bilateral inferior frontal gyri including Broca's area and superior temporal gyrus including primary auditory cortex. Bilateral middle temporal, left precentral and right middle occipital gyri were also showed enhanced neuronal activity. This result showed that rTMS over left lateral cerebellum modulate direct vicinity of the targeted region and a large network of remote interconnected contralateral motor and ipsilateral language related brain regions. Present result provide evidence that cerebellum may contribute to language related cognitive function as well as motor control

  15. Approaches using molecular imaging technology - use of PET in clinical microdose studies§

    OpenAIRE

    Wagner, Claudia C.; Langer, Oliver

    2011-01-01

    Positron emission tomography (PET) imaging uses minute amounts of radiolabeled drug tracers and thereby meets the criteria for clinical microdose studies. The advantage of PET, when compared to other analytical methods used in microdose studies, is that the pharmacokinetics (PK) of a drug can be determined in the tissue targeted for drug treatment. PET microdosing already offers interesting applications in clinical oncology and in the development of central nervous system pharmaceuticals and ...

  16. PET/CT colonography in patients with colorectal polyps: a feasibility study

    International Nuclear Information System (INIS)

    Mainenti, Pier P.; Pace, Leonardo; Salvatore, Marco; Salvatore, Barbara; D'Antonio, Dario; Bucci, Luigi; De Falco, Teresa; De Palma, Giovanni D.; D'Armiento, Francesco P.

    2007-01-01

    To examine: (1) the feasibility of PET/CT colonography (PET/CTc) in patients with colorectal polyps; (2) the impact of metabolic information on CTc interpretation and, conversely, the impact of morphological information on PET characterisation of focal colorectal uptake. Ten patients with colorectal polyps underwent PET/CTc, followed within 3 h by therapeutic conventional colonoscopy (CC). A radiologist and a nuclear medicine physician analysed the PET/CTc images. The agreement of morphological and metabolic information in the colon and rectum was evaluated. The sensitivity and specificity of PET, CT and PET/CT were calculated for colorectal polyps. Seventeen polypoid lesions were identified at CC: six≤5 mm, six between 6 and 9 mm, and five ≥10 mm (four hyperplastic polyps, 11 tubular adenomas, one adenocarcinoma and one submucosal lipoma). A total of 20 scans (supine and prone) were performed in the ten patients: the agreement of morphological and metabolic information was excellent in 17 scans, good in two and moderate in one. PET/CTc showed a sensitivity of 91% for lesions ≥6 mm and a specificity of 100%. The metabolic information did not disclose any further polyps missed on CTc. The morphological information permitted correct classification of all eight instances of focal radiotracer uptake. PET/CTc is a feasible study. Adding a colonographic protocol to PET/CT images seems to allow correct characterisation of all cases of colorectal focal radiotracer uptake. The metabolic information does not seem to increase the accuracy of CTc. (orig.)

  17. Clinical studies on the use of PET in radiotherapy planning in Germany. An update; Klinische Studien zum Einsatz der PET in der Bestrahlungsplanung in Deutschland. Ein Update

    Energy Technology Data Exchange (ETDEWEB)

    Nestle, U.; Mix, M.; Weber, W.; Grosu, A.L. [Universitaetsklinikum Freiburg (Germany). Kliniken fuer Strahlenheilkunde und Nuklearmedizin

    2011-07-15

    In recent years, PET and PET/CT have well been established for staging and restaging of various malignancies. Increasingly, the modality is also used for radiotherapy treatment planning. However, clinical studies investigating the patients benefit by the inclusion of those modalities into RT treatment planning are mandatory, simultaneously defining standards for future care. Chances and problems of such studies are discussed using the examples of the PET-Plan and GLIAA trials. (orig.)

  18. PET functional volume delineation: a robustness and repeatability study

    International Nuclear Information System (INIS)

    Hatt, Mathieu; Cheze-le Rest, Catherine; Albarghach, Nidal; Pradier, Olivier; Visvikis, Dimitris

    2011-01-01

    Current state-of-the-art algorithms for functional uptake volume segmentation in PET imaging consist of threshold-based approaches, whose parameters often require specific optimization for a given scanner and associated reconstruction algorithms. Different advanced image segmentation approaches previously proposed and extensively validated, such as among others fuzzy C-means (FCM) clustering, or fuzzy locally adaptive bayesian (FLAB) algorithm have the potential to improve the robustness of functional uptake volume measurements. The objective of this study was to investigate robustness and repeatability with respect to various scanner models, reconstruction algorithms and acquisition conditions. Robustness was evaluated using a series of IEC phantom acquisitions carried out on different PET/CT scanners (Philips Gemini and Gemini Time-of-Flight, Siemens Biograph and GE Discovery LS) with their associated reconstruction algorithms (RAMLA, TF MLEM, OSEM). A range of acquisition parameters (contrast, duration) and reconstruction parameters (voxel size) were considered for each scanner model, and the repeatability of each method was evaluated on simulated and clinical tumours and compared to manual delineation. For all the scanner models, acquisition parameters and reconstruction algorithms considered, the FLAB algorithm demonstrated higher robustness in delineation of the spheres with low mean errors (10%) and variability (5%), with respect to threshold-based methodologies and FCM. The repeatability provided by all segmentation algorithms considered was very high with a negligible variability of <5% in comparison to that associated with manual delineation (5-35%). The use of advanced image segmentation algorithms may not only allow high accuracy as previously demonstrated, but also provide a robust and repeatable tool to aid physicians as an initial guess in determining functional volumes in PET. (orig.)

  19. A study on client needs regarding FDG-PET for cancer screening

    International Nuclear Information System (INIS)

    Yamane, Tomohiko; Yoshiya, Kazuhiko; Nagata, Takeshi; Ito, Shinichi; Ito, Satoshi; Mezaki, Yukio; Uchida, Hideo

    2006-01-01

    We researched client needs regarding FDG-PET for cancer screening. The study included 1,527 individuals who underwent FDG-PET for cancer screening at our hospital. An interview sheet was distributed after injecting FDG. Clients listed the organs that required examination and the symptoms causing them anxiety. Results indicated that 9.8% of the clients listed organs for which FDG-PET would not be useful in detecting cancer. This study suggested that there exists a gap between client needs and FDG-PET utility; hence we need improved methods of providing correct information to clients. (author)

  20. O-15-butanol PET activation study on declarative memory

    International Nuclear Information System (INIS)

    Krause, B.J.; Schmidt, D.; Mottaghy, F.M.; Mueller-Gaertner, H.W.; Forschungszentrum Juelich; Halsband, U.; Tellmann, L.; Herzog, H.

    1998-01-01

    Aim: In this study, neuroanatomical correlates of encoding and retrieval in paired associate learning were evaluated with positron emission tomography using auditorily presented highly imaginable words. Methods: Six right-handed normal male volunteers took part in the study. Each subject underwent six O-15-butanol PET scans. On each of the six trials the memory task began with the injection of a bolus of O-15-butanol. The subjects had to learn and retrieve twelve word pairs (highly imaginable words, not semantically related). The presentation of nonsense words served as reference condition. Results: Recall accuracy after 2-4 presentations was high during the PET measurement. In both encoding and retrieval we found anterior cingulate activation. We show bilateral dorsalateral prefrontal activation during the encoding of auditorily presented word pair associates, whereas retrieval led to left frontal activation. Furthermore, we demonstrate the importance of the precuneus in the retrieval of highly imaginable world-pair associates. Conclusion: Our results support the hypothesis of the presence of distributed widespread brain structures subserving episodic declarative memory. (orig.) [de

  1. Progress of PET imaging in the study of neural stem cell transplantation treating Parkinson's disease

    International Nuclear Information System (INIS)

    Tan Haibo; Liu Xingdang

    2004-01-01

    PET imaging has important value in the study of neural stem cell transplantation treating Parkinson's disease, especial in the evaluation of the effect, the study of treating mechanisms and the comparation of effect in different transplantation places. PET imaging as a non-invasive method plays a more and more important role in the study of neural stem cell transplantation treating Parkinson's disease. (authors)

  2. One repetition maximum bench press performance: a new approach for its evaluation in inexperienced males and females: a pilot study.

    Science.gov (United States)

    Bianco, Antonino; Filingeri, Davide; Paoli, Antonio; Palma, Antonio

    2015-04-01

    The aim of this study was to evaluate a new method to perform the one repetition maximum (1RM) bench press test, by combining previously validated predictive and practical procedures. Eight young male and 7 females participants, with no previous experience of resistance training, performed a first set of repetitions to fatigue (RTF) with a workload corresponding to ⅓ of their body mass (BM) for a maximum of 25 repetitions. Following a 5-min recovery period, a second set of RTF was performed with a workload corresponding to ½ of participants' BM. The number of repetitions performed in this set was then used to predict the workload to be used for the 1RM bench press test using Mayhew's equation. Oxygen consumption, heart rate and blood lactate were monitored before, during and after each 1RM attempt. A significant effect of gender was found on the maximum number of repetitions achieved during the RTF set performed with ½ of participants' BM (males: 25.0 ± 6.3; females: 11.0x± 10.6; t = 6.2; p bench press test. We conclude that, by combining previously validated predictive equations with practical procedures (i.e. using a fraction of participants' BM to determine the workload for an RTF set), the new method we tested appeared safe, accurate (particularly in females) and time-effective in the practical evaluation of 1RM performance in inexperienced individuals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Bone formation rather than inflammation reflects Ankylosing Spondylitis activity on PET-CT: a pilot study

    OpenAIRE

    Bruijnen, Stefan TG; van der Weijden, Mignon AC; Klein, Joannes P; Hoekstra, Otto S; Boellaard, Ronald; van Denderen, J Christiaan; Dijkmans, Ben AC; Voskuyl, Alexandre E; van der Horst-Bruinsma, Irene E; van der Laken, Conny J

    2012-01-01

    Introduction Positron Emission Tomography - Computer Tomography (PET-CT) is an interesting imaging technique to visualize Ankylosing Spondylitis (AS) activity using specific PET tracers. Previous studies have shown that the PET tracers [18F]FDG and [11C](R)PK11195 can target inflammation (synovitis) in rheumatoid arthritis (RA) and may therefore be useful in AS. Another interesting tracer for AS is [18F]Fluoride, which targets bone formation. In a pilot setting, the potential of PET-CT in ima...

  4. Annihilation photon acollinearity in PET: volunteer and phantom FDG studies

    Energy Technology Data Exchange (ETDEWEB)

    Shibuya, Kengo [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Yoshida, Eiji [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Nishikido, Fumihiko [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Suzuki, Toshikazu [Department of Dose Assessment, Research Center for Radiation Emergency Medicine, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Tsuda, Tomoaki [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Inadama, Naoko [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Yamaya, Taiga [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Murayama, Hideo [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan)

    2007-09-07

    Annihilation photon acollinearity is a fundamental but little investigated problem in positron emission tomography (PET). In this paper, the cause of the angular deviation from 180.00{sup 0} is described as well as how to evaluate it under conditions of a spatially distributed radiation source and a limited acquisition time for the human body. A relationship between the shape of the photopeak spectrum and the angular distribution is formulated using conservation laws of momentum and energy over the pair annihilation. Then the formula is used to evaluate the acollinearity for a pool phantom and the human body with FDG injected. The angular distribution for the pool phantom agrees well with that for pure water which had been directly measured by Colombino et al in 1965 (Nuovo Cimento 38 707-23), and also with that for the human body determined in this study. Pure water can be considered as a good approximation of the human body regarding the angular deviation. The blurring coefficient to be multiplied by the ring diameter in calculations of the PET spatial resolution is experimentally determined for the first time as 0.00243 {+-} 0.00014; this is 10% larger than the value widely used by investigators.

  5. An experimental phantom study of the effect of gadolinium-based MR contrast agents on PET attenuation coefficients and PET quantification in PET-MR imaging: application to cardiac studies.

    Science.gov (United States)

    O' Doherty, Jim; Schleyer, Paul

    2017-12-01

    Simultaneous cardiac perfusion studies are an increasing trend in PET-MR imaging. During dynamic PET imaging, the introduction of gadolinium-based MR contrast agents (GBCA) at high concentrations during a dual injection of GBCA and PET radiotracer may cause increased attenuation effects of the PET signal, and thus errors in quantification of PET images. We thus aimed to calculate the change in linear attenuation coefficient (LAC) of a mixture of PET radiotracer and increasing concentrations of GBCA in solution and furthermore, to investigate if this change in LAC produced a measurable effect on the image-based PET activity concentration when attenuation corrected by three different AC strategies. We performed simultaneous PET-MR imaging of a phantom in a static scenario using a fixed activity of 40 MBq [18 F]-NaF, water, and an increasing GBCA concentration from 0 to 66 mM (based on an assumed maximum possible concentration of GBCA in the left ventricle in a clinical study). This simulated a range of clinical concentrations of GBCA. We investigated two methods to calculate the LAC of the solution mixture at 511 keV: (1) a mathematical mixture rule and (2) CT imaging of each concentration step and subsequent conversion to LAC at 511 keV. This comparison showed that the ranges of LAC produced by both methods are equivalent with an increase in LAC of the mixed solution of approximately 2% over the range of 0-66 mM. We then employed three different attenuation correction methods to the PET data: (1) each PET scan at a specific millimolar concentration of GBCA corrected by its corresponding CT scan, (2) each PET scan corrected by a CT scan with no GBCA present (i.e., at 0 mM GBCA), and (3) a manually generated attenuation map, whereby all CT voxels in the phantom at 0 mM were replaced by LAC = 0.1 cm -1 . All attenuation correction methods (1-3) were accurate to the true measured activity concentration within 5%, and there were no trends in image

  6. The Effectiveness of Computer-Based Spaced Repetition in Foreign Language Vocabulary Instruction: A Double-Blind Study

    Science.gov (United States)

    Chukharev-Hudilainen, Evgeny; Klepikova, Tatiana A.

    2016-01-01

    The purpose of the present paper is twofold; first, we present an empirical study evaluating the effectiveness of a novel CALL tool for foreign language vocabulary instruction based on spaced repetition of target vocabulary items. The study demonstrates that by spending an average of three minutes each day on automatically generated vocabulary…

  7. Poststroke dysphagia rehabilitation by repetitive transcranial magnetic stimulation: a noncontrolled pilot study.

    Science.gov (United States)

    Verin, E; Leroi, A M

    2009-06-01

    Poststroke dysphagia is frequent and significantly increases patient mortality. In two thirds of cases there is a spontaneous improvement in a few weeks, but in the other third, oropharyngeal dysphagia persists. Repetitive transcranial magnetic stimulation (rTMS) is known to excite or inhibit cortical neurons, depending on stimulation frequency. The aim of this noncontrolled pilot study was to assess the feasibility and the effects of 1-Hz rTMS, known to have an inhibitory effect, on poststroke dysphagia. Seven patients (3 females, age = 65 +/- 10 years), with poststroke dysphagia due to hemispheric or subhemispheric stroke more than 6 months earlier (56 +/- 50 months) diagnosed by videofluoroscopy, participated in the study. rTMS at 1 Hz was applied for 20 min per day every day for 5 days to the healthy hemisphere to decrease transcallosal inhibition. The evaluation was performed using the dysphagia handicap index and videofluoroscopy. The dysphagia handicap index demonstrated that the patients had mild oropharyngeal dysphagia. Initially, the score was 43 +/- 9 of a possible 120 which decreased to 30 +/- 7 (p study demonstrated that rTMS is feasible in poststroke dysphagia and improves swallowing coordination. Our results now need to be confirmed by a randomized controlled study with a larger patient population.

  8. Evaluation of Multiclass Model Observers in PET LROC Studies

    Science.gov (United States)

    Gifford, H. C.; Kinahan, P. E.; Lartizien, C.; King, M. A.

    2007-02-01

    A localization ROC (LROC) study was conducted to evaluate nonprewhitening matched-filter (NPW) and channelized NPW (CNPW) versions of a multiclass model observer as predictors of human tumor-detection performance with PET images. Target localization is explicitly performed by these model observers. Tumors were placed in the liver, lungs, and background soft tissue of a mathematical phantom, and the data simulation modeled a full-3D acquisition mode. Reconstructions were performed with the FORE+AWOSEM algorithm. The LROC study measured observer performance with 2D images consisting of either coronal, sagittal, or transverse views of the same set of cases. Versions of the CNPW observer based on two previously published difference-of-Gaussian channel models demonstrated good quantitative agreement with human observers. One interpretation of these results treats the CNPW observer as a channelized Hotelling observer with implicit internal noise

  9. Approaches using molecular imaging technology -- use of PET in clinical microdose studies.

    Science.gov (United States)

    Wagner, Claudia C; Langer, Oliver

    2011-06-19

    Positron emission tomography (PET) imaging uses minute amounts of radiolabeled drug tracers and thereby meets the criteria for clinical microdose studies. The advantage of PET, when compared to other analytical methods used in microdose studies, is that the pharmacokinetics (PK) of a drug can be determined in the tissue targeted for drug treatment. PET microdosing already offers interesting applications in clinical oncology and in the development of central nervous system pharmaceuticals and is extending its range of application to many other fields of pharmaceutical medicine. Although requirements for preclinical safety testing for microdose studies have been cut down by regulatory authorities, radiopharmaceuticals increasingly need to be produced under good manufacturing practice (GMP) conditions, which increases the costs of PET microdosing studies. Further challenges in PET microdosing include combining PET with other ultrasensitive analytical methods, such as accelerator mass spectrometry (AMS), to gain plasma PK data of drugs, beyond the short PET examination periods. Finally, conducting clinical PET studies with radiolabeled drugs both at micro- and therapeutic doses is encouraged to answer the question of dose linearity in clinical microdosing. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Approaches using molecular imaging technology - use of PET in clinical microdose studies§

    Science.gov (United States)

    Wagner, Claudia C; Langer, Oliver

    2013-01-01

    Positron emission tomography (PET) imaging uses minute amounts of radiolabeled drug tracers and thereby meets the criteria for clinical microdose studies. The advantage of PET, when compared to other analytical methods used in microdose studies, is that the pharmacokinetics (PK) of a drug can be determined in the tissue targeted for drug treatment. PET microdosing already offers interesting applications in clinical oncology and in the development of central nervous system pharmaceuticals and is extending its range of application to many other fields of pharmaceutical medicine. Although requirements for preclinical safety testing for microdose studies have been cut down by regulatory authorities, radiopharmaceuticals increasingly need to be produced under good manufacturing practice (GMP) conditions, which increases the costs of PET microdosing studies. Further challenges in PET microdosing include combining PET with other ultrasensitive analytical methods, such as accelerator mass spectrometry (AMS), to gain plasma PK data of drugs, beyond the short PET examination periods. Finally, conducting clinical PET studies with radiolabeled drugs both at micro- and therapeutic doses is encouraged to answer the question of dose linearity in clinical microdosing. PMID:20887762

  11. Using a Popular Pet Fish Species to Study Territorial Behaviour

    Science.gov (United States)

    Abante, Maria E.

    2005-01-01

    The colourful, vigorous territorial display behaviour of the Siamese fighting fish, "Betta splendens", has great appeal for both pet enthusiasts and animal behaviourists. Their beauty, longevity, easy maintenance and rearing make them a popular pet and an ideal science laboratory specimen. This investigation utilises "B. splendens" to test for the…

  12. Atmospheric tracer study of the emissions from the University of Michigan Cyclotron/PET Facility

    International Nuclear Information System (INIS)

    Scofield, P.A.

    1986-01-01

    The University of Michigan (U of M) Cyclotron/Positron Emission Tomography (PET) facility consists of a cyclotron (Model CS-30, The Cyclotron Corporation), radiochemistry laboratory, and Pet scanner. Accelerator-produced radioactive materials, such as, carbon-11 and oxygen-15 are typically emitted from the Cyclotron/PET facility through short stacks located on the roof. This project studied the dispersion of emissions from the facility within the medical complex. To achieve this purpose, the research project had three phases: a physical modeling study; a preliminary field smoke release study; and, a field study using a tracer gas to simulate emission dispersion from the U of M Cyclotron/PET facility vault stack. The objective was to determine normalized concentrations, under selected wind directions and speeds, for use in establishing radionuclide concentrations at the air intakes of the Cyclotron/PET facility and surrounding buildings and at selected ground-level locations

  13. The consumption and recycling collection system of PET bottles: a case study of Beijing, China.

    Science.gov (United States)

    Zhang, Hua; Wen, Zong-Guo

    2014-06-01

    After studying the recycling collection system of polyethylene terephthalate (PET) bottles worldwide, the authors conducted an intercept survey in Beijing. Two separate questionnaires were issued, one questionnaire to PET bottle consumers and one to PET bottle recyclers. In this study, consumers are defined as people that consume PET-bottled beverages in their daily life. Recyclers were defined as those involved in the collection and recycling of PET bottles. These include scavengers, itinerant waste buyers, small community waste-buying depots, medium/large redemption depots, and recycling companies. In total, 580 surveys were completed, including 461 by consumers and 119 by recyclers. The authors found that consumption of PET bottles in Beijing was nearly 100,000 tonnes in 2012. Age, occupation, gender, and education were identified as significant factors linked to PET-bottled beverage consumption, while income was not a significant factor. 90% Of post-consumed PET bottles were collected by informal collectors (i.e., scavengers and itinerant waste buyers). The survey also found that nearly all PET bottles were reprocessed by small factories that were not designed with pollution control equipment, which allows them to offer higher prices for waste recyclable bottles. As Beijing is trying to build a formal recycling collection system for recyclables, subsidies should be given to the formal recycling sector rather than being charged land use fees, and attention should also be given to informal recyclers that make their living from the collection of recyclables. Informal and formal sectors may work together by employing the scavengers and itinerant waste buyers for the formal sectors. In addition to the recycling of PET bottles, concern should also be allocated to reduce consumption, especially among young people, as they, compared to other groups, have a stronger demand for PET-bottled beverages and will be the main body of society. Copyright © 2013 Elsevier Ltd

  14. Uniformity studies inter cut with continuous movement PET stretcher; Homogeneidad intercorte de estudios PET con movimiento continuo de camila

    Energy Technology Data Exchange (ETDEWEB)

    Cons Perez, N.; Gomez Gonzalez, N.; Garcia Repiso, S.; Hernandez Rodriguez, J.; Montes Fuentes, C.; Garcia Ledesma, J.; Diez Gallego, M. A.

    2015-07-01

    One of the latest advances in PET scanners is the introduction of acquisitions with continuous movement of stretcher (CBM) Among the benefits that this technology brings they are: lower axial variation of noise, greater flexibility in planning studies with different levels of statistics for different anatomical and greater patient comfort regions. Behavior unexpected because the concentration obtained in all CBMs studies with PET-CT scanner Biograph mCTFlow (Slemens Medica Solutions) we propose a quantitative analysis with a series of parameters chosen to assess the inhomogeneity between cuts in the concentration obtained by homogeneous mannequins. A comparison with studies of static bed (S and S) indicates a problem only mode dynamic bed. (Author)

  15. TOF-PET scanner configurations for quality assurance in proton therapy: a patient case study

    NARCIS (Netherlands)

    Dendooven, Peter; Diblen, Faruk; Buitenhuis, H.J.T.; Oxley, D.C.; Biegun, A.K.; van der Borden, A.J.; Brandenburg, Sijtze; Cambraia Lopes, P.; van der Schaaf, A.; Schaart, D.R.; Vandenberghe, S.; van 't Veld, A.A.

    2014-01-01

    In order to determine the clinical benefit of positron emission tomography (PET) for dose delivery verification in proton therapy, we performed a patient case study comparing in-situ with in-room time-of-flight (TOF) PET. For the in-situ option, we consider both a (limited-angle) clinical scanner

  16. Comparison of the performance of {sup 18}F-FP-CIT brain PET/MR and simultaneous PET/CT: A preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Sang Don; Chun, Kyung Ah [Dept. of Nuclear Medicine, Yeungnam University Hospital, Daegu (Korea, Republic of)

    2016-09-15

    {sup 18}F-FP-CIT [{sup 1'}8F-fluorinated N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) nortropane] has been well established and used for the differential diagnosis of atypical parkinsonian disorders. Recently, combined positron emission tomography (PET)/magnetic resonance (MR) was proposed as a viable alternative to PET/computed tomography (CT). The aim of this study was to compare the performances of conventional {sup 18}F-FP-CIT brain PET/CT and simultaneous PET/MR by visual inspection and quantitative analysis. Fifteen consecutive patients clinically suspected of having Parkinson's disease were recruited for the study.{sup 18}F-FP-CIT PET was performed during PET/CT and PET/MR. PET/CT image acquisition was started 90 min after intravenous injection of {sup 18}F-FP-CIT and then PET/MR images were acquired. Dopamine transporter (DAT) density in bilateral striatal subregions was assessed visually. Quantitative analyses were performed on bilateral striatal volumes of interest (VOIs) using average standardized uptake values (SUVmeans). Intraclass correlation coefficients (ICCs) and their 95 % confidence intervals (CIs) were assessed to compare PET/CT and PET/MR data. Bland-Altman plots were drawn to perform method-comparisons. All subjects showed a preferential decrease in DAT binding in the posterior putamen (PP), with relative sparing of the ventral putamen (VP). Bilateral striatal subregional binding ratio (BR) determined PET/CT and PET/MR demonstrated close interequipment correspondence (BRright caudate - ICC, 0.944; 95 % CI, 0.835-0.981, BRleft caudate - ICC, 0.917; 95 % CI, 0.753-0.972, BRright putamen - ICC, 0.976; 95 % CI, 0.929-0.992 and BRleft putamen - ICC, 0.970; 95 % CI, 0.911-0.990, respectively), and Bland-Altman plots showed interequipment agreement between the two modalities. It is known that MR provides more information about anatomical changes associated with brain diseases and to enable the anatomical allocations of

  17. Experimental study of plume induced by nanosecond repetitively pulsed spark microdischarges in air at atmospheric pressure

    Science.gov (United States)

    Orriere, Thomas; Benard, Nicolas; Moreau, Eric; Pai, David

    2016-09-01

    Nanosecond repetitively pulsed (NRP) spark discharges have been widely studied due to their high chemical reactivity, low gas temperature, and high ionization efficiency. They are useful in many research areas: nanomaterials synthesis, combustion, and aerodynamic flow control. In all of these fields, particular attention has been devoted to chemical species transport and/or hydrodynamic and thermal effects for applications. The aim of this study is to generate an electro-thermal plume by combining an NRP spark microdischarge in a pin-to-pin configuration with a third DC-biased electrode placed a few centimeters away. First, electrical characterization and optical emission spectroscopy were performed to reveal important plasma processes. Second, particle image velocimetry was combined with schlieren photography to investigate the main characteristics of the generated flow. Heating processes are measured by using the N2(C ->B) (0,2) and (1,3) vibrational bands, and effects due to the confinement of the discharge are described. Moreover, the presence of atomic ions N+ and O+ is discussed. Finally, the electro-thermal plume structure is characterized by a flow velocity around 1.8 m.s-1, and the thermal kernel has a spheroidal shape.

  18. Repetitive Stress Injuries

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Repetitive Stress Injuries KidsHealth / For Teens / Repetitive Stress Injuries What's ... t had any problems since. What Are Repetitive Stress Injuries? Repetitive stress injuries (RSIs) are injuries that ...

  19. Development of 68Ga ethyl cysteinate dimer for PET studies

    International Nuclear Information System (INIS)

    Alireza Mirzaei; Jalilian, A.R.; Gholamali Shabani; Ashraf Fakhari; Mehdi Akhlaghi; Davood Beiki

    2016-01-01

    In this work development of 68 Ga-ethyl cysteinate dimer ( 68 Ga-ECD) a 68 Ga tracer for possible cerebral blood flow based on 99m Tc ECD homolog is reported. 68 Ga-ECD was prepared using generator-based 68 GaCl 3 and ECD at optimized conditions. Quality control, stability, partition co-efficient and the biodistribution of the tracer (by tissue counting and PET/CT in rats) was studied. Significant metabolism of the lipophilic tracer into water soluble metabolite(s) led to urinary excretion of the tracer, un-comparable to that of homologous 99m Tc-compound. Cardiac uptake of the complex suggests formation of a possible lipophil cationic complex and/or metabolite. (author)

  20. Study of a Cherenkov TOF-PET module

    Science.gov (United States)

    Korpar, S.; Dolenec, R.; Križan, P.; Pestotnik, R.; Stanovnik, A.

    2013-12-01

    An apparatus, consisting of two PbF2 crystals, each coupled to a multichannel plate photomultiplier (MCP-PMT), has been constructed in order to measure the time-of-flight (TOF) of the two 511 keV annihilation photons produced in positron emission tomography (PET). Excellent timing is achieved by detecting the prompt Cherenkov photons produced by the absorption of the 511 keV gamma photons. The present work describes the measurement and image reconstruction of two 22Na point sources. In addition, the influence of the radiator thickness and the Cherenkov light absorption cut-off of the crystal on the efficiency and the timing resolution have been studied by Monte Carlo simulation.

  1. The impact of PET-CT in suspected recurrent ovarian cancer: A prospective multi-centre study as part of the Australian PET Data Collection Project.

    Science.gov (United States)

    Fulham, M J; Carter, J; Baldey, A; Hicks, R J; Ramshaw, J E; Gibson, M

    2009-03-01

    To assess the impact of FDG PET-CT on the management of patients with suspected recurrent ovarian cancer and to determine the incremental information provided by PET-CT. This was a prospective, multi-centre, cohort study. Ninety women (mean age 59.9 years; age range 35-85 years) with a previous history of treated epithelial ovarian carcinoma and suspected recurrence based on elevated CA-125, anatomical imaging or clinical symptoms were studied with FDG PET-CT across two States. Referring doctors were asked to specify a management plan pre-PET, if management was altered after PET-CT and, the impact (rated - none, low, medium, high) of PET-CT on patient management. The pre-PET management plan could include radiotherapy, chemotherapy, surgery, and 'other' including observation. Patients were followed at 6 and 12 months and clinical status, evidence of recurrence and progression were recorded. Patients were referred by 34 individual specialists. At least 168 additional sites of disease in 61 patients (68%), not identified by conventional imaging were identified by PET-CT. In 77% the additional lesions were located below the diaphragm and most were nodal or peritoneal. PET-CT affected management in 60% (49% high, 11% medium impact). Patients where more disease was detected with PET-CT were more likely to progress in the following 12 months. For women with previously treated ovarian carcinoma with recurrent disease, PET-CT can: a) alter management in close to 60% of patients, b) detect more sites of disease than abdominal and pelvic CT, c) is superior in the detection of nodal, peritoneal and subcapsular liver disease and d) offers the opportunity for technology replacement in this setting.

  2. A prospective study of the clinical impact of PET scanning in lung cancer patients

    International Nuclear Information System (INIS)

    Hicks, R.J.; Kalff, V.; Binns, D.S.; McManus, M.; Millward, M.; Ball, D.J.

    1998-01-01

    Full text: PET scanning using F-18 fluorodeoxyglucose (FDG), has been shown to very accurately stage patients with non-small cell lung cancer. At this Institute these patients are only sent for PET imaging where there remains any significant doubt as to their clinical staging or management after the completion of conventional screening test including CT scanning. This study examines how PET scan findings influenced the clinical management decisions in 45 consecutive patients (26 males, mean age 69±9 yrs: range 36-78 yrs). Referring doctors were asked to indicate reason for the PET scan, stage their patients on the basis of aU their current investigations, including CT scans, and to indicate their management plans prior to PET scanning. Follow-up of subsequent patient management at 2-4 weeks post PET scan was then obtained and compared to pre scan plans. Results:, PET was used to stage 27 patients, restage 8, plan radiotherapy in 4, post treatment follow-up in 3, assess solitary nodules in 2, and as a baseline for experimental therapy in 1. To date follow-up has shown that in 14 (31%) patients PET scanning found new distant abnormalities which caused planned radical surgery or radiotherapy to be changed to palliative treatment only. Following PET findings, which clarified equivocal findings on other imaging modalities 9 patients underwent curative lung surgery. This found localised disease only in the 5 who have had surgery to this time. Similarly 7 patients continued on to have radical radiotherapy. In 3 patients, original treatment protocols changed (smaller radiation portal, surgery after good response to radiotherapy, planned chemotherapy ceased). In 8(18%) patients PET scans did not alter planned therapy. 1 patient awaits follow-up. Conclusions: In carefully selected patients with lung cancer, PET scanning significantly affected management decisions in 82%. It was used not only to spare unnecessary treatment, but also to target treatment appropriate to

  3. Comparison of the diagnostic accuracy of PET/MRI to PET/CT-acquired FDG brain exams for seizure focus detection: a prospective study

    Energy Technology Data Exchange (ETDEWEB)

    Paldino, Michael J.; Jones, Jeremy Y.; Mahmood, Nadia; Sher, Andrew; Hayatghaibi, Shireen; Seghers, Victor [Texas Children' s Hospital, Department of Radiology, Houston, TX (United States); Yang, Erica [SimonMed Imaging, Department of Radiology, Scottsdale, AZ (United States); Zhang, Wei [Texas Children' s Hospital, Outcomes and Impact Service, Houston, TX (United States); Krishnamurthy, Ramkumar [Nationwide Children' s Hospital, Department of Radiology, Columbus, OH (United States)

    2017-10-15

    There is great interest in positron emission tomography (PET)/magnetic resonance (MR) as a clinical tool due to its capacity to provide diverse diagnostic information in a single exam. The goal of this exam is to compare the diagnostic accuracy of PET/MR-acquired [F-18]2-fluoro-2-deoxyglucose (FDG) brain exams to that of PET/CT with respect to identifying seizure foci in children with localization-related epilepsy. Institutional Review Board approval and informed consent were obtained for this Health Insurance Portability and Accountability Act-compliant, prospective study. All patients referred for clinical FDG-PET/CT exams of the brain at our institution for a diagnosis of localization-related epilepsy were prospectively recruited to undergo an additional FDG-PET acquisition on a tandem PET/MR system. Attenuation-corrected FDG images acquired at PET/MR and PET/CT were interpreted independently by five expert readers. Readers were blinded to the scanner used for acquisition and attenuation correction as well as all other clinical and imaging data. A Likert scale scoring system (1-5) was used to assess image quality. The locale of seizure origin determined at multidisciplinary epilepsy surgery work rounds was considered the reference standard. Non-inferiority testing for paired data was used to compare the diagnostic accuracy of PET/MR to that of PET/CT. The final study population comprised 35 patients referred for a diagnosis of localization-related epilepsy (age range: 2-19 years; median: 11 years; 21 males, 14 females). Image quality did not differ significantly between the two modalities. The accuracy of PET/MR was not inferior to that of PET/CT for localization of a seizure focus (P=0.017). The diagnostic accuracy of FDG-PET images acquired on a PET/MR scanner and generated using MR-based attenuation correction was not inferior to that of PET images processed by traditional CT-based correction. (orig.)

  4. Comparison of the diagnostic accuracy of PET/MRI to PET/CT-acquired FDG brain exams for seizure focus detection: a prospective study

    International Nuclear Information System (INIS)

    Paldino, Michael J.; Jones, Jeremy Y.; Mahmood, Nadia; Sher, Andrew; Hayatghaibi, Shireen; Seghers, Victor; Yang, Erica; Zhang, Wei; Krishnamurthy, Ramkumar

    2017-01-01

    There is great interest in positron emission tomography (PET)/magnetic resonance (MR) as a clinical tool due to its capacity to provide diverse diagnostic information in a single exam. The goal of this exam is to compare the diagnostic accuracy of PET/MR-acquired [F-18]2-fluoro-2-deoxyglucose (FDG) brain exams to that of PET/CT with respect to identifying seizure foci in children with localization-related epilepsy. Institutional Review Board approval and informed consent were obtained for this Health Insurance Portability and Accountability Act-compliant, prospective study. All patients referred for clinical FDG-PET/CT exams of the brain at our institution for a diagnosis of localization-related epilepsy were prospectively recruited to undergo an additional FDG-PET acquisition on a tandem PET/MR system. Attenuation-corrected FDG images acquired at PET/MR and PET/CT were interpreted independently by five expert readers. Readers were blinded to the scanner used for acquisition and attenuation correction as well as all other clinical and imaging data. A Likert scale scoring system (1-5) was used to assess image quality. The locale of seizure origin determined at multidisciplinary epilepsy surgery work rounds was considered the reference standard. Non-inferiority testing for paired data was used to compare the diagnostic accuracy of PET/MR to that of PET/CT. The final study population comprised 35 patients referred for a diagnosis of localization-related epilepsy (age range: 2-19 years; median: 11 years; 21 males, 14 females). Image quality did not differ significantly between the two modalities. The accuracy of PET/MR was not inferior to that of PET/CT for localization of a seizure focus (P=0.017). The diagnostic accuracy of FDG-PET images acquired on a PET/MR scanner and generated using MR-based attenuation correction was not inferior to that of PET images processed by traditional CT-based correction. (orig.)

  5. Metallic artifacts caused by dental metal prostheses on PET images. A PET/CT phantom study using different PET/CT scanners

    International Nuclear Information System (INIS)

    Shimamoto, Hiroaki; Kakimoto, Naoya; Murakami, Shumei; Furukawa, Souhei; Fujino, Kouichi; Hamada, Seiki; Shimosegawa, Eku; Hatazawa, Jun

    2009-01-01

    The objective of this study was to investigate the effects of computed tomography (CT) artifacts caused by dental metal prostheses on positron emission tomography (PET) images. A dental arch cast was fixed in a cylindrical water-bath phantom. A spherical phantom positioned in the vicinity of the dental arch cast was used to simulate a tumor. To simulate the tumor imaging, the ratio of the 18 F-fluoro-deoxy-glucose radioactivity concentration of the spherical phantom to that of the water-bath phantom was set at 2.5. A dental bridge composed of a gold-silver-palladium alloy on the right mandibular side was prepared. A spherical phantom was set in the white artifact area on the CT images (site A), in a slightly remote area from the white artifact (site B), and in a black artifact area (site C). A PET/CT scan was performed with and without the metal bridge at each simulated tumor site, and the artifactual influence was evaluated on the axial attenuation-corrected (AC) PET images, in which the simulated tumor produced the strongest accumulation. Measurements were performed using three types of PET/CT scanners (scanners 1 and 2 with CT-based attenuation correction, and 3 with Cesium-137 ( 137 Cs)-based attenuation correction). The influence of the metal bridge was evaluated using the change rate of the SUVmean with and without the metal bridge. At site A, an overestimation was shown (scanner 1: +5.0% and scanner 2: +2.5%), while scanner 3 showed an underestimation of -31.8%. At site B, an overestimation was shown (scanner 1: +2.1% and scanner 2: +2.0%), while scanner 3 showed an underestimation of -2.6%. However, at site C, an underestimation was shown (scanner 1: -25.0%, scanner 2: -32.4%, and scanner 3: -8.4%). When CT is used for attenuation correction in patients with dental metal prostheses, an underestimation of radioactivity of accumulated tracer is anticipated in the dark streak artifact area on the CT images. In this study, the dark streak artifacts of the CT

  6. REPETITIVE TMS ON LEFT CEREBELLUM AFFECTS IMPULSIVITY IN BORDERLINE PERSONALITY DISORDER : A PILOT STUDY

    Directory of Open Access Journals (Sweden)

    Giulia Zelda De Vidovich

    2016-12-01

    Full Text Available The borderline personality disorder (BPD is characterized by a severe pattern of instability in emotional regulation, interpersonal relationships, identity, and impulse control. These functions are related to the prefrontal cortex (PFC, and since PFC shows a rich anatomical connectivity with the cerebellum, the functionality of the cerebellar-PFC axis may impact on BPD. In this study we investigated the potential involvement of cerebello-thalamo-cortical connections in impulsive reactions through a pre/post stimulation design. BPD patients (n=8 and healthy controls (HC; n=9 performed an Affective Go/No-Go task (AGN assessing information processing biases for positive and negative stimuli before and after repetitive transcranial magnetic stimulation (rTMS; 1 Hz/10 min, 80% RMT over the left lateral cerebellum. The AGN task consisted of four blocks requiring associative capacities of increasing complexity. BPD patients performed significantly worse than the HC, especially when cognitive demands was high (3rd and 4th block, but their performace approached that of HC after rTMS (rTMS was almost ineffective in HC. The more evident effect of rTMS in complex associative tasks might have occurred since the cerebellum is deeply involved in integration and coordination of different stimuli. We hypothesize that, in BPD patients, cerebello-thalamo-cortical communication is altered, resulting in emotional dysregulation and disturbed impulse control. The rTMS over the left cerebellum might have interfered with existing functional connections exerting a facilitating effect on PFC control.

  7. Face repetition detection and social interest: An ERP study in adults with and without Williams syndrome.

    Science.gov (United States)

    Key, Alexandra P; Dykens, Elisabeth M

    2016-12-01

    The present study examined possible neural mechanisms underlying increased social interest in persons with Williams syndrome (WS). Visual event-related potentials (ERPs) during passive viewing were used to compare incidental memory traces for repeated vs. single presentations of previously unfamiliar social (faces) and nonsocial (houses) images in 26 adults with WS and 26 typical adults. Results indicated that participants with WS developed familiarity with the repeated faces and houses (frontal N400 response), but only typical adults evidenced the parietal old/new effect (previously associated with stimulus recollection) for the repeated faces. There was also no evidence of exceptional salience of social information in WS, as ERP markers of memory for repeated faces vs. houses were not significantly different. Thus, while persons with WS exhibit behavioral evidence of increased social interest, their processing of social information in the absence of specific instructions may be relatively superficial. The ERP evidence of face repetition detection in WS was independent of IQ and the earlier perceptual differentiation of social vs. nonsocial stimuli. Large individual differences in ERPs of participants with WS may provide valuable information for understanding the WS phenotype and have relevance for educational and treatment purposes.

  8. Repetitive TMS on Left Cerebellum Affects Impulsivity in Borderline Personality Disorder: A Pilot Study.

    Science.gov (United States)

    De Vidovich, Giulia Zelda; Muffatti, Riccardo; Monaco, Jessica; Caramia, Nicoletta; Broglia, Davide; Caverzasi, Edgardo; Barale, Francesco; D'Angelo, Egidio

    2016-01-01

    The borderline personality disorder (BPD) is characterized by a severe pattern of instability in emotional regulation, interpersonal relationships, identity and impulse control. These functions are related to the prefrontal cortex (PFC), and since PFC shows a rich anatomical connectivity with the cerebellum, the functionality of the cerebellar-PFC axis may impact on BPD. In this study, we investigated the potential involvement of cerebello-thalamo-cortical connections in impulsive reactions through a pre/post stimulation design. BPD patients ( n = 8) and healthy controls (HC; n = 9) performed an Affective Go/No-Go task (AGN) assessing information processing biases for positive and negative stimuli before and after repetitive transcranial magnetic stimulation (rTMS; 1 Hz/10 min, 80% resting motor threshold (RMT) over the left lateral cerebellum. The AGN task consisted of four blocks requiring associative capacities of increasing complexity. BPD patients performed significantly worse than the HC, especially when cognitive demands were high (third and fourth block), but their performance approached that of HC after rTMS (rTMS was almost ineffective in HC). The more evident effect of rTMS in complex associative tasks might have occurred since the cerebellum is deeply involved in integration and coordination of different stimuli. We hypothesize that in BPD patients, cerebello-thalamo-cortical communication is altered, resulting in emotional dysregulation and disturbed impulse control. The rTMS over the left cerebellum might have interfered with existing functional connections exerting a facilitating effect on PFC control.

  9. Comparative study of FDG-PET and sestamibi-SPECT in the diagnosis of secondary hyperparathyroidism

    International Nuclear Information System (INIS)

    Higuchi, T.; Ozawa, K.; Oriuchi, N.; Khan, N.; Endo, K.; Otake, H.; Matsubara, K.

    2002-01-01

    Aim: FDG-PET is reported to be more accurate in preoperative localization of hyper functioning parathyroid gland of primary hyperparathyroidism in comparison with sestamibi-SPECT by Neumann et al. However, its usefulness in the diagnosis of secondary hyperparathyroidism has not been reported yet. In this study, we've performed the direct comparison of the usefulness of FDG-PET and sestamibi-SPECT in the detection of abnormal parathyroid tissue in the patients of secondary hyperparathyroidism under hemodilysis. Material and Methods: One primary and 5 secondary hyperparathyroidism patients underwent FDG-PET and sestamibi-SPECT. After overnight fasting, 300 to 400 MBq of FDG was intravenously injected, followed by whole body PET image acquisition after 50 minutes. In the same day before FDG-PET, 600 MBq of sestamibi was injected and early and delayed planar image and delayed SPECT image has been obtained. Visual interpretation of the abnormal parathyroid uptake has been performed by 2 experienced nuclear physician independently. Results: In the secondary cases, FDG-PET shows no hyper functioning gland in all 5 cases, whereas sestamibi-SPECT shows 8 hyper functioning glands. In contrast, hyper functioning gland of the primary hyperparathyroidism case has been clearly visualized only by FDG-PET. Conclusion: Although FDG-PET is very useful in detecting hyper functioning gland in primary hyperparathyroidism, it is not useful in secondary hyperparathyroidism. Further pathological analysis about the different glucose metabolism of primary and secondary hyper functioning gland should be added in the future study

  10. PET and PET/CT with radiolabeled choline in prostate cancer: a critical reappraisal of 20 years of clinical studies

    Energy Technology Data Exchange (ETDEWEB)

    Giovacchini, Giampiero; Giovannini, Elisabetta; Leoncini, Rossella; Riondato, Mattia; Ciarmiello, Andrea [S. Andrea Hospital, Nuclear Medicine Department, La Spezia (Italy)

    2017-09-15

    We here aim to provide a comprehensive and critical review of the literature concerning the clinical applications of positron emission tomography/computed tomography (PET/CT) with radiolabeled choline in patients with prostate cancer (PCa). We will initially briefly summarize the historical context that brought to the synthesis of [{sup 11}C]choline, which occurred exactly 20 years ago. We have arbitrarily grouped the clinical studies in three different periods, according to the year in which they were published and according to their relation with their applications in urology, radiotherapy and oncology. Studies at initial staging and, more extensively, studies in patients with biochemical failure, as well as factors predicting positive PET/CT will be reviewed. The capability of PET/CT with radiolabeled choline to provide prognostic information on PCa-specific survival will also be examined. The last sections will be devoted to the use of radiolabeled choline for monitoring the response to androgen deprivation therapy, radiotherapy, and chemotherapy. The accuracy and the limits of the technique will be discussed according to the information available from standard validation processes, including biopsy or histology. The clinical impact of the technique will be discussed on the basis of changes induced in the management of patients and in the evaluation of the response to therapy. Current indications to PET/CT, as officially endorsed by guidelines, or as routinely performed in the clinical practice will be illustrated. Emphasis will be made on methodological factors that might have influenced the results of the studies or their interpretation. Finally, we will briefly highlight the potential role of positron emission tomography/magnetic resonance and of new radiotracers for PCa imaging. (orig.)

  11. NEMA NU 2-2012 performance studies for the SiPM-based ToF-PET component of the GE SIGNA PET/MR system

    Energy Technology Data Exchange (ETDEWEB)

    Grant, Alexander M. [Department of Bioengineering, Stanford University, Stanford, California 94305-5128 and Department of Radiology, Stanford University, Stanford, California 94305-5128 (United States); Deller, Timothy W.; Maramraju, Sri Harsha [GE Healthcare, Waukesha, Wisconsin 53188-1678 (United States); Khalighi, Mohammad Mehdi [GE Healthcare, Applied Science Lab, Menlo Park, California 94025-3493 (United States); Delso, Gaspar [GE Healthcare and University Hospital of Zurich, Zurich 8006 (Switzerland); Levin, Craig S., E-mail: cslevin@stanford.edu [Department of Bioengineering, Stanford University, Stanford, California 94305-5128 (United States); Department of Radiology, Stanford University, Stanford, California 94305-5128 (United States); Department of Electrical Engineering, Stanford University, Stanford, California 94305-5128 (United States); Department of Physics, Stanford University, Stanford, California 94305-5128 (United States)

    2016-05-15

    Purpose: The GE SIGNA PET/MR is a new whole body integrated time-of-flight (ToF)-PET/MR scanner from GE Healthcare. The system is capable of simultaneous PET and MR image acquisition with sub-400 ps coincidence time resolution. Simultaneous PET/MR holds great potential as a method of interrogating molecular, functional, and anatomical parameters in clinical disease in one study. Despite the complementary imaging capabilities of PET and MRI, their respective hardware tends to be incompatible due to mutual interference. In this work, the GE SIGNA PET/MR is evaluated in terms of PET performance and the potential effects of interference from MRI operation. Methods: The NEMA NU 2-2012 protocol was followed to measure PET performance parameters including spatial resolution, noise equivalent count rate, sensitivity, accuracy, and image quality. Each of these tests was performed both with the MR subsystem idle and with continuous MR pulsing for the duration of the PET data acquisition. Most measurements were repeated at three separate test sites where the system is installed. Results: The scanner has achieved an average of 4.4, 4.1, and 5.3 mm full width at half maximum radial, tangential, and axial spatial resolutions, respectively, at 1 cm from the transaxial FOV center. The peak noise equivalent count rate (NECR) of 218 kcps and a scatter fraction of 43.6% are reached at an activity concentration of 17.8 kBq/ml. Sensitivity at the center position is 23.3 cps/kBq. The maximum relative slice count rate error below peak NECR was 3.3%, and the residual error from attenuation and scatter corrections was 3.6%. Continuous MR pulsing had either no effect or a minor effect on each measurement. Conclusions: Performance measurements of the ToF-PET whole body GE SIGNA PET/MR system indicate that it is a promising new simultaneous imaging platform.

  12. NEMA NU 2-2012 performance studies for the SiPM-based ToF-PET component of the GE SIGNA PET/MR system

    International Nuclear Information System (INIS)

    Grant, Alexander M.; Deller, Timothy W.; Maramraju, Sri Harsha; Khalighi, Mohammad Mehdi; Delso, Gaspar; Levin, Craig S.

    2016-01-01

    Purpose: The GE SIGNA PET/MR is a new whole body integrated time-of-flight (ToF)-PET/MR scanner from GE Healthcare. The system is capable of simultaneous PET and MR image acquisition with sub-400 ps coincidence time resolution. Simultaneous PET/MR holds great potential as a method of interrogating molecular, functional, and anatomical parameters in clinical disease in one study. Despite the complementary imaging capabilities of PET and MRI, their respective hardware tends to be incompatible due to mutual interference. In this work, the GE SIGNA PET/MR is evaluated in terms of PET performance and the potential effects of interference from MRI operation. Methods: The NEMA NU 2-2012 protocol was followed to measure PET performance parameters including spatial resolution, noise equivalent count rate, sensitivity, accuracy, and image quality. Each of these tests was performed both with the MR subsystem idle and with continuous MR pulsing for the duration of the PET data acquisition. Most measurements were repeated at three separate test sites where the system is installed. Results: The scanner has achieved an average of 4.4, 4.1, and 5.3 mm full width at half maximum radial, tangential, and axial spatial resolutions, respectively, at 1 cm from the transaxial FOV center. The peak noise equivalent count rate (NECR) of 218 kcps and a scatter fraction of 43.6% are reached at an activity concentration of 17.8 kBq/ml. Sensitivity at the center position is 23.3 cps/kBq. The maximum relative slice count rate error below peak NECR was 3.3%, and the residual error from attenuation and scatter corrections was 3.6%. Continuous MR pulsing had either no effect or a minor effect on each measurement. Conclusions: Performance measurements of the ToF-PET whole body GE SIGNA PET/MR system indicate that it is a promising new simultaneous imaging platform.

  13. PERIPHERAL APPLICATION OF REPETITIVE PULSE MAGNETIC STIMULATION ON JOINT CONTRACTURE FOR MOBILITY RESTORATION: CONTROLLED RANDOMIZED STUDY

    Directory of Open Access Journals (Sweden)

    Efthimios J. Kouloulas

    2016-10-01

    Full Text Available Background: Joint contracture is a limitation in the passive or active range of motion (ROM of a joint, where in addition to the mobility limiting factor the pain is also present. Repetitive pulsed Magnetic Stimulation (rPMS appears to be an effective, non-invasive and safety solution for treating this condition. Therefore aim of this study was to evaluate the effect of rPMS in treating joint contracture. Methods: 30 subjects with joint contracture in the knee were enrolled in this study and divided respectively into Treatment and Control group. The treatment group were delivered with rPMS therapy. The control group was delivered with conventional physiotherapy method (ultrasound. The primary outcome measurements were: 1. Mobility evaluation by goniometry (ROM in degrees while performing flexion and Patient Functional Assessment Questionnaire (PFAQ for ability to perform Activities of Daily Living (ADL and 2. Pain evaluation by 10-point Visual Analog Scale (VAS for pain perception. Absence of adverse events was set as a secondary measure. Results: The results of the study show statistical difference (p<0.05 between the levels of improvement of all studied parameters while comparing between both groups. The results suggest greater immobility restoration and pain relieving effect of the rPMS in comparison to conventional physiotherapy method. Conclusion: rPMS an effective and safe non-invasive method for mobility restoration and pain relief in case of joint contractures. This study suggests the method as beneficial and quality of life ameliorating among patients suffering from immobilized joints accompanied by pain.

  14. Preparation of the PET/PP/PE/EVA polymeric blend from PET bottles and modification studies induced by ionizing radiation

    International Nuclear Information System (INIS)

    Rossini, Edvaldo Luis

    2005-01-01

    The environmental pollution is one of the biggest problems nowadays. Amidst the pollutants, plastic and especially the packings type P ET bottles , which comprise of poly(ethylene terephthalate) (PET), polypropylene (PP), polyethylene (PE) and poly[ethylene-co-(vinyl acetate)] (EVA) are causing big damage in the environment. In this work, the polymeric blend PET/PP/PE/EVA was obtained by a process of simplified mechanical recycling from 'PET bottles' after consumption, with the objective to find solution to this environmental problem. It was also studied the different ionizing radiation doses effects (25, 50, 75, 100, 150, 200, 300, 400 e 500 kGy) on the blend properties using an electron beam accelerator. The mechanical (tensile strength, impact and hardness), thermal (Vicat softening temperature, differential scanning calorimetry and termogravimetric) and microscopic (light microscopy and scanning electron microscopy) properties of the blend were studied. The analysis of the results showed to be a not mixing and compatible blend, with mechanical and thermal properties (which appeared to be similar to the properties of the component material used in the blend in separate) satisfactory, resulting in a resistant material and of low cost, being able to be used in the production of parts that do not demand specifications techniques. The use of the ionizing radiation improved some of the mechanical and thermal properties of the blend (these modifications had been random and irregular, depending directly on the dose of applied radiation and the type of property) making possible more specific applications for this material. (author)

  15. Nonword Repetition Priming in Lexical Decision Reverses as a Function of Study Task and Speed Stress

    Science.gov (United States)

    Zeelenberg, Rene; Wagenmakers, Eric-Jan; Shiffrin, Richard M.

    2004-01-01

    The authors argue that nonword repetition priming in lexical decision is the net result of 2 opposing processes. First, repeating nonwords in the lexical decision task results in the storage of a memory trace containing the interpretation that the letter string is a nonword; retrieval of this trace leads to an increase in performance for repeated…

  16. A Pilot Study Comparing Two Nonword Repetition Tasks for Use in a Formal Test Battery

    Science.gov (United States)

    Tattersall, Patricia J.; Nelson, Nickola Wolf; Tyler, Ann A.

    2015-01-01

    Two sets of nonwords (with and without true morphemes) were compared for their ability to differentiate students in Grades 1 through 12 with and without language impairment (36 each; N = 72) on a nonword repetition task. Results indicated that either nonword type could contribute to differential diagnosis.

  17. Understanding repetitive travel mode choices in a stable context: A panel study approach

    DEFF Research Database (Denmark)

    Thøgersen, John

    2006-01-01

    It is argued that most travel mode choices are repetitive and made in a stable context. As an example, the everyday use of public transport is analyzed based on a panel survey with a random sample of about 1300 Danish residents interviewed up to three times in the period 1998-2000. The use...

  18. Effects of Immediate Repetition in L2 Speaking Tasks: A Focused Study

    Science.gov (United States)

    Bei, Gavin Xiaoyue

    2013-01-01

    This paper reports on a focused investigation into the immediate effects of oral narrative task repetition by two adult EFL learners of intermediate and high proficiency. Two participants performed a narrative speaking task after watching a cartoon video clip and repeated their performance three times, followed by a retrospective report in an…

  19. Mantram repetition for stress management in veterans and employees: a critical incident study.

    Science.gov (United States)

    Bormann, Jill E; Oman, Doug; Kemppainen, Jeanne K; Becker, Sheryl; Gershwin, Madeline; Kelly, Ann

    2006-03-01

    This paper reports a study assessing the usefulness of a mantram repetition programme. Complementary/alternative therapies are becoming commonplace, but more research is needed to assess their benefits. A 5-week programme teaching a 'mind-body-spiritual' technique of silently repeating a mantram - a word or phrase with spiritual meaning - to manage stress was developed. A mantram was chosen by individuals, who were taught to repeat it silently throughout the day or night to interrupt unwanted thoughts and elicit the relaxation response. Participants who attended a 5-week course were invited to participate in the study. Of those who consented, a randomly selected subset (n = 66) was contacted approximately 3 months after the course for a telephone interview using the critical incident interviewing technique. Participants were asked whether the intervention was helpful or not, and if helpful, to identify situations where it was applied. Interviews were transcribed and incidents were identified and categorized to create a taxonomy of uses. The data were collected in 2001-2002. Participants included 30 veterans, mostly males (97%), and 36 hospital employees, mostly females (86%). Mean age was 56 years (sd = 12.94). Fifty-five participants (83.3%) practiced the technique and reported 147 incidents where the programme was helpful. Outcomes were organized into a taxonomy of incidents using four major categories that included managing: (a) emotions other than stress (51%); (b) stress (23.8%); (c) insomnia (12.9%); and (d) unwanted thoughts (12.3%). A group of raters reviewed the categories for inter-rater reliability. The majority of participants from two distinct samples reported that the mantram programme was helpful in a variety of situations. The critical incident interviewing method was found to be practical, efficient, and thorough in collecting and analyzing data. Such qualitative methods contribute to understanding the benefits of mind-body complementary therapies.

  20. Quantitative imaging studies with PET VI. Project II

    International Nuclear Information System (INIS)

    Copper, M.; Chen, C.T.; Yasillo, N.; Gatley, J.; Ortega, C.; DeJesus, O.; Friedman, A.

    1985-01-01

    This project is focused upon the development of hardware and software to improve PET image analysis and upon clinical applications of PET. In this report the laboratory's progress in various attenuation correction methods for brain imaging are described. The use of time-of-flight information for image reconstruction is evaluated. The location of dopamine D1 and D2 receptors in brain was found to be largely in the basal ganghia. 1 tab. (DT)

  1. A comparative study on PET and SPECT image formation systems for a proper scanner choice in a considered PET center

    International Nuclear Information System (INIS)

    Santos, G.R. dos; Oliveira, A. de; Oliveira, C.L. de

    2001-01-01

    Full text: In the last twenty years, the conjunction of technology and research had provided exceptional conditions for improvements on the quality of life, specially on nuclear medicine. In this area, the developed technology is being applied, making available better diagnoses and therapy to a variety of diseases. Since then the short-lived radionuclides were available only in the large physics research centers. The increasing clinical applications have led to the rapid rise in the number of compact cyclotrons throughout the world. All medical cyclotrons currently are suitable for sustaining programs for PET research and clinical application. To date, up to 122 medical cyclotrons have been established worldwide, and Brazil is about to install a new dedicated cyclotron (RDS111 from CTI), to its first PET Center, in Rio de Janeiro. Also the number of scanners worldwide has increased, mainly those based on the positrons emission and annihilation. The better result gotten in the final contrast of the object imposes a comparative study and analysis of the image formation process, either in a system based on a Single Photon Emission Computerized Tomography (SPECT), as well as on Positron Emission Tomography (PET.) This comparative study should at least follow same increasing rates of the new devices with technological advances. That kind of study can be helpful on the decision of what type of scan should be the proper one, to a PET Center, on a specific region. Obviously, many other parameters are involved in that decision, and this discussion and analyses are the main subject of the present work. The objective is to make available a realistic comparative scenario. Many of the new devices have been introduced making progresses. As an example, in the new PET scanners, the reduction of examination time, and the remarkable improvement on the diagnoses based on images. As a consequence, we have a broadening on application, better performance, and making possible the

  2. Design study of a low-emittance high-repetition rate thermionic rf gun

    Directory of Open Access Journals (Sweden)

    A. Opanasenko

    2017-05-01

    Full Text Available We propose a novel gridless continuous-wave radiofrequency (rf thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.

  3. Comparative study of ipsilesional and contralesional repetitive transcranial magnetic stimulations for acute infarction.

    Science.gov (United States)

    Watanabe, Kosuke; Kudo, Yosuke; Sugawara, Eriko; Nakamizo, Tomoki; Amari, Kazumitsu; Takahashi, Koji; Tanaka, Osamu; Endo, Miho; Hayakawa, Yuko; Johkura, Ken

    2018-01-15

    Repetitive transcranial magnetic stimulation (rTMS) is reported to improve chronic post-stoke hemiparesis. However, application of rTMS during the acute phase of post-stroke has not fully been investigated. We investigated the safety and the efficacy of intermittent theta-burst stimulation (iTBS) of the affected motor cortex and 1-Hz stimulation of the unaffected hemisphere during the acute phase in patients with hemiparesis due to capsular infarction. Twenty one patients who met the study criteria were randomly assigned to receive, starting within 7days after stroke onset and for a period of 10days, iTBS of the affected motor cortex hand area (n=8), 1-Hz stimulation of the unaffected motor cortex hand area (n=7), or sham stimulation (n=6). Upper limb motor function was evaluated before rTMS and 12weeks after onset of the stroke. Evaluation was based on the Fugl-Meyer Assessment (FMA), Stroke Impairment Assessment Set (SIAS), Modified Ashworth Scale (MAS), grip strength, and motor evoked potential (MEP) amplitude in the first dorsal interosseous (FDI) muscle. Both iTBS applied to the affected motor cortex hand area and 1-Hz stimulation applied to the unaffected motor cortex hand area enhanced motor recovery. In comparison to sham stimulation, iTBS increased the SIAS finger-function test score, and 1-Hz stimulation decreased the MAS wrist and finger score. Ipsilesional iTBS and contralesional 1-Hz stimulation applied during the acute phase of stroke have different effects: ipsilesional iTBS improves movement of the affected limb, whereas contralesional 1-Hz stimulation reduces spasticity of the affected limb. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Prognostic factors for low birthweight repetition in successive pregnancies: a cohort study

    Directory of Open Access Journals (Sweden)

    Sclowitz Iândora Krolow Timm

    2013-01-01

    Full Text Available Abstract Background To identify prognostic factors associated with recurrence of low birthweight (LBW in successive gestations, a study was carried out with a subsample of mothers enrolled in the 2004 Pelotas Birth Cohort. Methods Data were collected by hospital-based interviews. Newborns were weighed and measured. Gestational age was defined according to the date of last menstrual period, ultra-sound scan before the 20th week of pregnancy or the Dubowitz method. Mothers who reported at least one LBW newborn in the two previous gestations were included. Prevalence ratios (PR and 95% confidence intervals were estimated from Poisson Regression. All estimates were adjusted for parity. Results A total of 4558 births were identified in 2004, and 565 met inclusion criteria, out of which 86 (15.2% repeated LBW in 2004. Among mothers with two LBW babies before 2004, 47.9% presented LBW recurrence. Belonging to the highest socio-economic stratum (PR 0.89; 0.01-0.46 and gaining ≥ 10 kg during pregnancy (PR 0.09; 0.01-0.77 were protective against LBW recurrence. Higher risk of LBW recurrence was observed among mothers with higher parity (≥3 previous deliveries; PR=1.93; 95% CI 1.23-3.02; who had given birth to a previous preterm baby (PR=4.01; 2.27-7.10; who delivered a female newborn in current gestation (PR=2.61; 1.45-4.69; and that had not received adequate antenatal care (PR=2.57; 1-37-4.81. Conclusion Improved quality of antenatal care and adequate maternal weight gain during pregnancy may be feasible strategies to prevent LBW repetition in successive pregnancies.

  5. A phenomenographic study of the ways of understanding conditional and repetition structures in computer programming languages

    Science.gov (United States)

    Bucks, Gregory Warren

    Computers have become an integral part of how engineers complete their work, allowing them to collect and analyze data, model potential solutions and aiding in production through automation and robotics. In addition, computers are essential elements of the products themselves, from tennis shoes to construction materials. An understanding of how computers function, both at the hardware and software level, is essential for the next generation of engineers. Despite the need for engineers to develop a strong background in computing, little opportunity is given for engineering students to develop these skills. Learning to program is widely seen as a difficult task, requiring students to develop not only an understanding of specific concepts, but also a way of thinking. In addition, students are forced to learn a new tool, in the form of the programming environment employed, along with these concepts and thought processes. Because of this, many students will not develop a sufficient proficiency in programming, even after progressing through the traditional introductory programming sequence. This is a significant problem, especially in the engineering disciplines, where very few students receive more than one or two semesters' worth of instruction in an already crowded engineering curriculum. To address these issues, new pedagogical techniques must be investigated in an effort to enhance the ability of engineering students to develop strong computing skills. However, these efforts are hindered by the lack of published assessment instruments available for probing an individual's understanding of programming concepts across programming languages. Traditionally, programming knowledge has been assessed by producing written code in a specific language. This can be an effective method, but does not lend itself well to comparing the pedagogical impact of different programming environments, languages or paradigms. This dissertation presents a phenomenographic research study

  6. Pilot Study for the Prediction of Response to Radiotherapy Using [18F]Fluorothymidine PET in Nasopharyngeal Cancer: Comparison with [18F]FDG PET

    International Nuclear Information System (INIS)

    Baek, So Ra; Chae, Sun Young; Kim, Hye Ok; Lee, Sang Wook; Oh, Seung Jun; Im, Ki Chun; Moon, Dae Hyuk; Kim, Jae Seung; Ryu, Jin Sook

    2009-01-01

    This study was performed to know whether [ 18 F]Fluorothymidine (FLT) positron emission tomography (PET) can be used to monitor early response to radiotherapy in comparison with [ 18 F]Fluorodeoxyglucose (FDG) PET, and to establish the optimal imaging time for prediction of therapy response. Two patients with nasopharyngeal cancer underwent serial FLT PET and FDG PET before and during radiotherapy. Three on-treatment FLT and FDG PET scans were performed on 1 week, 2 weeks and 3 weeks (at each time of 10 Gy, 20 Gy and 30 Gy delivered). The peak standardized uptake values (SUV peak ) of primary tumors were measured on FLT and FDG PET. Then, percent changes of SUV peak after therapy were calculated. In two patients, baseline values of SUV peak on FDT PET were higher than those on FLT PET (FLT vs FDG; 3.7 vs 5.0, and 5.7 vs 15.0). In patient 1, FLT SUV peak showed 78%, 78% and 84% of decrease on 1 week, 2 and 3 weeks after treatment, whereas FDG SUV peak showed 18%, 52% and 66% of decrease, respectively. In patient 2, FLT SUV peak showed 75%, 75% and 68% of decrease, whereas FDG SUV peak showed 51%, 49% and 58% of decrease, respectively. Both patients reached to complete remission after radiotherapy. After radiotherapy, the decrease of FLT tumor uptake preceded the decrease of FDG tumor uptake in patients with nasopharyngeal cancer, and 1 week after therapy may be appropriate time for the assessment of early response. FLT PET might be more useful than FDG PET for monitoring early response to radiotherapy

  7. Anatomical and functional volume concordance between FDG PET, and T2 and diffusion-weighted MRI for cervical cancer: a hybrid PET/MR study

    International Nuclear Information System (INIS)

    Sun, Hongzan; Xin, Jun; Zhang, Shaomin; Guo, Qiyong; Lu, Yueyue; Zhai, Wei; Zhao, Long; Peng, Weiai; Wang, Baijun

    2014-01-01

    To evaluate the concordance among 18 F-FDG PET imaging, MR T2-weighted (T2-W) imaging and apparent diffusion coefficient (ADC) maps with diffusion-weighted (DW) imaging in cervical cancer using hybrid whole-body PET/MR. This study prospectively included 35 patients with cervical cancer who underwent pretreatment 18 F-FDG PET/MR imaging. 18 F-FDG PET and MR images were fused using standard software. The percent of the maximum standardized uptake values (SUV max ) was used to contour tumours on PET images, and volumes were calculated automatically. Tumour volumes measured on T2-W and DW images were calculated with standard techniques of tumour area multiplied by the slice profile. Parametric statistics were used for data analysis. FDG PET tumour volumes calculated using SUV max (14.30 ± 4.70) and T2-W imaging volume (33.81 ± 27.32 cm 3 ) were similar (P > 0.05) at 35 % and 40 % of SUV max (32.91 ± 18.90 cm 3 and 27.56 ± 17.19 cm 3 respectively) and significantly correlated (P 3 . DW volumes were not significantly different from FDG PET volumes at either 35 % SUV max or 40 % SUV max or from T2-W imaging volumes (P > 0.05). PET subvolumes with increasing SUV max cut-off percentage showed an inverse change in mean ADC values on DW imaging (P max is recommended for 18 F-FDG PET/MR SUV-based tumour volume estimation. The linear tumour subvolume concordance between FDG PET and DW imaging demonstrates individual regional concordance of metabolic activity and cell density. (orig.)

  8. MRI compatibility study of an integrated PET/RF-coil prototype system at 3 T

    Science.gov (United States)

    Akram, Md Shahadat Hossain; Obata, Takayuki; Suga, Mikio; Nishikido, Fumihiko; Yoshida, Eiji; Saito, Kazuyuki; Yamaya, Taiga

    2017-10-01

    We have been working on the development of a PET insert for existing magnetic resonance imaging (MRI) systems for simultaneous PET/MR imaging, which integrates radiofrequency (RF)-shielded PET detector modules with an RF head coil. In order to avoid interferences between the PET detector circuits and the different MRI-generated electromagnetic fields, PET detector circuits were installed inside eight Cu-shielded fiber-reinforced plastic boxes, and these eight shielded PET modules were integrated in between the eight elements of a 270-mm-diameter and 280-mm-axial-length cylindrical birdcage RF coil, which was designed to be used with a 3-T clinical MRI system. The diameter of the PET scintillators with a 12-mm axial field-of-view became 255 mm, which was very close to the imaging region. In this study, we have investigated the effects of this PET/RF-coil integrated system on the performance of MRI, which include the evaluation of static field (Bo) inhomogeneity, RF field (B1) distribution, local specific absorption rate (SAR) distribution, average SAR, and signal-to-noise ratio (SNR). For the central 170-mm-diameter and 80-mm-axial-length of a homogenous cylindrical phantom (with the total diameter of 200 mm and axial-length of 100 mm), an increase of about a maximum of 3 μT in the Bo inhomogeneity was found, both in the central and 40-mm off-centered transverse planes, and a 5 percentage point increase of B1 field inhomogeneity was observed in the central transverse plane (from 84% without PET to 79% with PET), while B1 homogeneity along the coronal plane was almost unchanged (77%) following the integration of PET with the RF head coil. The average SAR and maximum local SAR were increased by 1.21 and 1.62 times, respectively. However, the SNR study for both spin-echo and gradient-echo sequences showed a reduction of about 70% and 60%, respectively, because of the shielded PET modules. The overall results prove the feasibility of this integrated PET/RF-coil system

  9. Effects of Repetitive Transcranial Magnetic Stimulation in Performing Eye-Hand Integration Tasks: Four Preliminary Studies with Children Showing Low-Functioning Autism

    Science.gov (United States)

    Panerai, Simonetta; Tasca, Domenica; Lanuzza, Bartolo; Trubia, Grazia; Ferri, Raffaele; Musso, Sabrina; Alagona, Giovanna; Di Guardo, Giuseppe; Barone, Concetta; Gaglione, Maria P.; Elia, Maurizio

    2014-01-01

    This report, based on four studies with children with low-functioning autism, aimed at evaluating the effects of repetitive transcranial magnetic stimulation delivered on the left and right premotor cortices on eye-hand integration tasks; defining the long-lasting effects of high-frequency repetitive transcranial magnetic stimulation; and…

  10. Comparison of 18F-FET PET and perfusion-weighted MRI for glioma grading. A hybrid PET/MR study

    International Nuclear Information System (INIS)

    Verger, Antoine; Filss, Christian P.; Lohmann, Philipp; Stoffels, Gabriele; Rota Kops, Elena; Sabel, Michael; Wittsack, Hans J.; Galldiks, Norbert; Fink, Gereon R.; Shah, Nadim J.; Langen, Karl-Josef

    2017-01-01

    Both perfusion-weighted MR imaging (PWI) and O-(2- 18 F-fluoroethyl)-L-tyrosine PET ( 18 F-FET) provide grading information in cerebral gliomas. The aim of this study was to compare the diagnostic value of 18 F-FET PET and PWI for tumor grading in a series of patients with newly diagnosed, untreated gliomas using an integrated PET/MR scanner. Seventy-two patients with untreated gliomas [22 low-grade gliomas (LGG), and 50 high-grade gliomas (HGG)] were investigated with 18 F-FET PET and PWI using a hybrid PET/MR scanner. After visual inspection of PET and PWI maps (rCBV, rCBF, MTT), volumes of interest (VOIs) with a diameter of 16 mm were centered upon the maximum of abnormality in the tumor area in each modality and the contralateral unaffected hemisphere. Mean and maximum tumor-to-brain ratios (TBR mean , TBR max ) were calculated. In addition, Time-to-Peak (TTP) and slopes of time-activity curves were calculated for 18 F-FET PET. Diagnostic accuracies of 18 F-FET PET and PWI for differentiating low-grade glioma (LGG) from high-grade glioma (HGG) were evaluated by receiver operating characteristic analyses (area under the curve; AUC). The diagnostic accuracy of 18 F-FET PET and PWI to discriminate LGG from HGG was similar with highest AUC values for TBR mean and TBR max of 18 F-FET PET uptake (0.80, 0.83) and for TBR mean and TBR max of rCBV (0.80, 0.81). In case of increased signal in the tumor area with both methods (n = 32), local hot-spots were incongruent in 25 patients (78%) with a mean distance of 10.6 ± 9.5 mm. Dynamic FET PET and combination of different parameters did not further improve diagnostic accuracy. Both 18 F-FET PET and PWI discriminate LGG from HGG with similar diagnostic performance. Regional abnormalities in the tumor area are usually not congruent indicating that tumor grading by 18 F-FET PET and PWI is based on different pathophysiological phenomena. (orig.)

  11. Comparison of {sup 18}F-FET PET and perfusion-weighted MRI for glioma grading. A hybrid PET/MR study

    Energy Technology Data Exchange (ETDEWEB)

    Verger, Antoine [Forschungszentrum Juelich, Institute of Neuroscience and Medicine (INM-3, -4), Juelich (Germany); Lorraine University, Department of Nuclear Medicine and Nancyclotep Imaging Platform, CHRU Nancy, Nancy (France); Lorraine University, IADI, INSERM, UMR 947, Nancy (France); Filss, Christian P. [Forschungszentrum Juelich, Institute of Neuroscience and Medicine (INM-3, -4), Juelich (Germany); RWTH Aachen University Hospital, Department of Nuclear Medicine, Aachen (Germany); Lohmann, Philipp; Stoffels, Gabriele; Rota Kops, Elena [Forschungszentrum Juelich, Institute of Neuroscience and Medicine (INM-3, -4), Juelich (Germany); Sabel, Michael [University of Duesseldorf, Department of Neurosurgery, Duesseldorf (Germany); Wittsack, Hans J. [University Duesseldorf, Department of Diagnostic and Interventional Radiology, Medical Faculty, Duesseldorf (Germany); Galldiks, Norbert; Fink, Gereon R. [Forschungszentrum Juelich, Institute of Neuroscience and Medicine (INM-3, -4), Juelich (Germany); University of Cologne, Department of Neurology, Cologne (Germany); University of Cologne and Bonn, Center of Integrated Oncology (CIO), Bonn (Germany); Shah, Nadim J. [Forschungszentrum Juelich, Institute of Neuroscience and Medicine (INM-3, -4), Juelich (Germany); RWTH Aachen University Hospital, Department of Neurology, Aachen (Germany); Juelich-Aachen Research Alliance (JARA), Section JARA-Brain, Juelich (Germany); Langen, Karl-Josef [Forschungszentrum Juelich, Institute of Neuroscience and Medicine (INM-3, -4), Juelich (Germany); RWTH Aachen University Hospital, Department of Nuclear Medicine, Aachen (Germany); Juelich-Aachen Research Alliance (JARA), Section JARA-Brain, Juelich (Germany)

    2017-12-15

    Both perfusion-weighted MR imaging (PWI) and O-(2-{sup 18}F-fluoroethyl)-L-tyrosine PET ({sup 18}F-FET) provide grading information in cerebral gliomas. The aim of this study was to compare the diagnostic value of {sup 18}F-FET PET and PWI for tumor grading in a series of patients with newly diagnosed, untreated gliomas using an integrated PET/MR scanner. Seventy-two patients with untreated gliomas [22 low-grade gliomas (LGG), and 50 high-grade gliomas (HGG)] were investigated with {sup 18}F-FET PET and PWI using a hybrid PET/MR scanner. After visual inspection of PET and PWI maps (rCBV, rCBF, MTT), volumes of interest (VOIs) with a diameter of 16 mm were centered upon the maximum of abnormality in the tumor area in each modality and the contralateral unaffected hemisphere. Mean and maximum tumor-to-brain ratios (TBR{sub mean}, TBR{sub max}) were calculated. In addition, Time-to-Peak (TTP) and slopes of time-activity curves were calculated for {sup 18}F-FET PET. Diagnostic accuracies of {sup 18}F-FET PET and PWI for differentiating low-grade glioma (LGG) from high-grade glioma (HGG) were evaluated by receiver operating characteristic analyses (area under the curve; AUC). The diagnostic accuracy of {sup 18}F-FET PET and PWI to discriminate LGG from HGG was similar with highest AUC values for TBR{sub mean} and TBR{sub max} of {sup 18}F-FET PET uptake (0.80, 0.83) and for TBR{sub mean} and TBR{sub max} of rCBV (0.80, 0.81). In case of increased signal in the tumor area with both methods (n = 32), local hot-spots were incongruent in 25 patients (78%) with a mean distance of 10.6 ± 9.5 mm. Dynamic FET PET and combination of different parameters did not further improve diagnostic accuracy. Both {sup 18}F-FET PET and PWI discriminate LGG from HGG with similar diagnostic performance. Regional abnormalities in the tumor area are usually not congruent indicating that tumor grading by {sup 18}F-FET PET and PWI is based on different pathophysiological phenomena. (orig.)

  12. Imaging results and TOF studies with axial PET detectors

    Science.gov (United States)

    Joram, Christian

    2013-12-01

    We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the field of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations (PET concept making use of the novel digital SiPM detectors by Philips. After reproducing comparable energy and spatial resolution on a small digital AX-PET set-up with 100 mm long crystals, we demonstrated a coincidence resolving time of about 210 ps FWHM.

  13. Differential preparation intervals modulate repetition processes in task switching: an ERP study

    Directory of Open Access Journals (Sweden)

    Min eWang

    2016-02-01

    Full Text Available In task-switching paradigms, reaction times (RTs switch cost (SC and the neural correlates underlying the SC are affected by different preparation intervals. However, little is known about the effect of the preparation interval on the repetition processes in task-switching. To examine this effect we utilized a cued task-switching paradigm with long sequences of repeated trials. Response-stimulus intervals (RSI and cue-stimulus intervals (CSI were manipulated in short and long conditions. Electroencephalography (EEG and behavioral data were recorded. We found that with increasing repetitions, RTs were faster in the short CSI conditions, while P3 amplitudes decreased in the LS (long RSI and short CSI conditions. Positive correlations between RT benefit and P3 activation decrease (repeat 1 minus repeat 5, and between the slope of the RT and P3 regression lines were observed only in the LS condition. Our findings suggest that differential preparation intervals modulate repetition processes in task switching.

  14. PET AND SPECT STUDIES IN CHILDREN WITH HEMISPHERIC LOW-GRADE GLIOMAS

    Science.gov (United States)

    Juhász, Csaba; Bosnyák, Edit

    2016-01-01

    Molecular imaging is playing an increasing role in the pre-treatment evaluation of low-grade gliomas. While glucose positron emission tomography (PET) can be helpful to differentiate low-grade from high-grade tumors, PET imaging with amino acid radiotracers has several advantages, such as better differentiation between tumors and non-tumorous lesions, optimized biopsy targeting and improved detection of tumor recurrence. This review provides a brief overview of single photon emission computed tomography (SPECT) studies followed by a more detailed review of clinical applications of glucose and amino acid PET imaging in low-grade hemispheric gliomas. We discuss key differences in the performance of the most commonly utilized PET radiotracers and highlight the advantage of PET/MRI fusion to obtain optimal information about tumor extent, heterogeneity and metabolism. Recent data also suggest that simultaneous acquisition of PET/MR images and the combination of advanced MRI techniques with quantitative PET can further improve the pre- and post-treatment evaluation of pediatric brain tumors. PMID:27659825

  15. International validation study for interim PET in ABVD-treated, advanced-stage hodgkin lymphoma

    DEFF Research Database (Denmark)

    Biggi, Alberto; Gallamini, Andrea; Chauvie, Stephane

    2013-01-01

    At present, there are no standard criteria that have been validated for interim PET reporting in lymphoma. In 2009, an international workshop attended by hematologists and nuclear medicine experts in Deauville, France, proposed to develop simple and reproducible rules for interim PET reporting...... in lymphoma. Accordingly, an international validation study was undertaken with the primary aim of validating the prognostic role of interim PET using the Deauville 5-point score to evaluate images and with the secondary aim of measuring concordance rates among reviewers using the same 5-point score...

  16. Scintillator studies for the HPD-PET concept

    CERN Document Server

    Braem, D; Ciocia, F; De Leo, R; Joram, C; Lagamba, L; Nappi, E; Séguinot, Jacques; Vilardi, I; Weilhammer, P

    2007-01-01

    The spatial, energy, and time resolutions of 10 cm long polished YAP:Ce and LYSO:Ce crystals have been measured. The work is part of the novel HPD-PET concept, based on a full three-dimensional, free of parallax errors, reconstruction of the γ-ray interaction point in 10–15 cm long scintillators. The effective light attenuation length, a key parameter of the HPD-PET concept, and the resolutions have been measured for various wrappings and coatings of the crystal lateral surfaces. Even if the final HPD-PET prototype could use scintillators and/or wrappings different from those tested, the results here presented prove the feasibility of the concept and provide hints on its potential capabilities.

  17. A new generation of PET scanners for small animal studies

    International Nuclear Information System (INIS)

    Hegyesi, G.; Imrek, J.; Kalinka, G.; Molnar, J.; Novak, D.; Valastyan, I.; Balkay, L.; Emri, M.; Kis, S.; Tron, L.

    2008-01-01

    Complete text of publication follows. Research on small animal PET scanners has been a hot topic in recent years. These devices are used in the preclinical phases of drug tests and during the development of new radiopharmaceuticals. They also provide a cost efficient way to test new materials, new design concepts and new technologies that later can be used to build more efficient human medical imaging devices. The development of a PET scanner requires expertise on different fields, therefore a consortium was formed that brought together Hungarian academic and industrial partners: the Nuclear Research Institute (which has experience in the development of nuclear detectors and data acquisition systems), the PET Center of the University of Debrecen (which has clinical experience in the application of nuclear imaging devices and background in image processing software), Mediso Ltd. (which has been developing, manufacturing, selling and servicing medical imaging devices since 1990) and other academic partners. This consortium has been working together since 2003: the knowledge base acquired during the development of our small animal PET scanners (miniPET-I and miniPET-II) is now being utilized to build a commercial multimodal human PET scanner. The operation of a PET scanner is based on the simultaneous detection ('coincidence') of two gamma photons originating from a positron annihilation. In traditional PET scanners coincidence is detected by a central unit during the measurement. In our system there is no such central module: all detected single gamma events are recorded (list mode data acquisition), and the list of events are processed using a computer cluster (built from PCs). The usage of independent detector modules and commercial components reduce both development and maintenance costs. Also, this mode of data acquisition is more suitable for development purposes, since once the data is collected and stored it can be used many times to test different signal

  18. Time-resolved studies at PETRA III with a highly repetitive synchronized laser system

    Energy Technology Data Exchange (ETDEWEB)

    Schlie, Mortiz

    2013-09-15

    Atomic and molecular processes can nowadays be directly followed in the time domain. This is a core technique for a better understanding of the involved fundamental physics, thus auguring new applications in the future as well. Usually the so-called pump-probe technique making use of two synchronized ultrashort light pulses is utilized to obtain this time-resolved data. In this work, the development and characterization of a synchronization system enabling such pump-probe studies at the storage ring PETRA III in combination with an external, then synchronized fs-laser system is described. The synchronization is based on an extended PLL approach with three interconnected feedback loops allowing to monitor short-time losses of the lock and thus prevent them. This way, the jitter between the laser PHAROS and the PETRA III reference signal is reduced to {sigma} <5 ps. Thus the system allows to conduct experiments at a repetition rate of 130 kHz with a temporal resolution limited only by the X-ray pulse length. A major emphasis in the fundamental introductory chapters is an intuitive explanation of the basic principles of phase locked loops and the different aspects of phase noise to allow a deeper understanding of the synchronization. Furthermore, first pump-probe experiments conducted at different beamlines at PETRA III are presented, demonstrating the usability of the laser system in a scientific environment as well. In first characterizing experiments the pulse duration of PETRA III X-ray pulses has been measured to be 90 ps FWHM. In particular, there have been time resolved X-ray absorption spectroscopy experiments on Gaq3 and Znq2 conducted at beamline P11. First results show dynamics of the electronic excitation on the timescale of a few hundred pico seconds up to a few nano seconds and provide a basic understanding for further research on those molecules. For Gaq3 this data is analyzed in detail and compared with visible fluorescence measurements suggesting at

  19. Time-resolved studies at PETRA III with a highly repetitive synchronized laser system

    International Nuclear Information System (INIS)

    Schlie, Mortiz

    2013-09-01

    Atomic and molecular processes can nowadays be directly followed in the time domain. This is a core technique for a better understanding of the involved fundamental physics, thus auguring new applications in the future as well. Usually the so-called pump-probe technique making use of two synchronized ultrashort light pulses is utilized to obtain this time-resolved data. In this work, the development and characterization of a synchronization system enabling such pump-probe studies at the storage ring PETRA III in combination with an external, then synchronized fs-laser system is described. The synchronization is based on an extended PLL approach with three interconnected feedback loops allowing to monitor short-time losses of the lock and thus prevent them. This way, the jitter between the laser PHAROS and the PETRA III reference signal is reduced to σ <5 ps. Thus the system allows to conduct experiments at a repetition rate of 130 kHz with a temporal resolution limited only by the X-ray pulse length. A major emphasis in the fundamental introductory chapters is an intuitive explanation of the basic principles of phase locked loops and the different aspects of phase noise to allow a deeper understanding of the synchronization. Furthermore, first pump-probe experiments conducted at different beamlines at PETRA III are presented, demonstrating the usability of the laser system in a scientific environment as well. In first characterizing experiments the pulse duration of PETRA III X-ray pulses has been measured to be 90 ps FWHM. In particular, there have been time resolved X-ray absorption spectroscopy experiments on Gaq3 and Znq2 conducted at beamline P11. First results show dynamics of the electronic excitation on the timescale of a few hundred pico seconds up to a few nano seconds and provide a basic understanding for further research on those molecules. For Gaq3 this data is analyzed in detail and compared with visible fluorescence measurements suggesting at least

  20. Fluorine-18 labeled tracers for PET studies in the neurosciences

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yu-Shin; Fowler, J.S.

    1995-12-31

    This chapter focuses on fluorine-18, the positron emitter with the longest half-life, the lowest positron energy and probably, the most challenging chemistry. The incorporation of F-18 into organic compounds presents many challenges, including: the need to synthesize and purify the compound within a 2--3 hour time frame; the limited number of labeled precursor molecules; the need to work on a microscale; and the need to produce radiotracers which are chemically and radiochemically pure, sterile and pyrogen-free, and suitable for intravenous injection. The PET method and F-18 labeling of organic molecules are described followed by highlights of the applications of F-18 labeled compounds in the neurosciences and neuropharmacology. It is important to emphasize the essential and pivotal role that organic synthesis has played in the progression of the PET field over the past twenty years from one in which only a handful of institutions possessed the instrumentation and staff to carry out research to the present-day situation where there are more than 200 PET centers worldwide. During this period PET has become an important scientific tool in the neurosciences, cardiology and oncology. It is important to point out that PET is by no means a mature field. The fact that a hundreds of different F-18 labeled compounds have been developed but only a few possess the necessary selectivity and sensitivity in vivo to track a specific biochemical process illustrates this and underscores a major difficulty in radiotracer development, namely the selection of priority structures for synthesis and the complexities of the interactions between chemical compounds and living systems. New developments in rapid organic synthesis are needed in order to investigate new molecular targets and to improve the quantitative nature of PET experiments.

  1. Fluorine-18 labeled tracers for PET studies in the neurosciences

    International Nuclear Information System (INIS)

    Ding, Yu-Shin; Fowler, J.S.

    1995-01-01

    This chapter focuses on fluorine-18, the positron emitter with the longest half-life, the lowest positron energy and probably, the most challenging chemistry. The incorporation of F-18 into organic compounds presents many challenges, including: the need to synthesize and purify the compound within a 2--3 hour time frame; the limited number of labeled precursor molecules; the need to work on a microscale; and the need to produce radiotracers which are chemically and radiochemically pure, sterile and pyrogen-free, and suitable for intravenous injection. The PET method and F-18 labeling of organic molecules are described followed by highlights of the applications of F-18 labeled compounds in the neurosciences and neuropharmacology. It is important to emphasize the essential and pivotal role that organic synthesis has played in the progression of the PET field over the past twenty years from one in which only a handful of institutions possessed the instrumentation and staff to carry out research to the present-day situation where there are more than 200 PET centers worldwide. During this period PET has become an important scientific tool in the neurosciences, cardiology and oncology. It is important to point out that PET is by no means a mature field. The fact that a hundreds of different F-18 labeled compounds have been developed but only a few possess the necessary selectivity and sensitivity in vivo to track a specific biochemical process illustrates this and underscores a major difficulty in radiotracer development, namely the selection of priority structures for synthesis and the complexities of the interactions between chemical compounds and living systems. New developments in rapid organic synthesis are needed in order to investigate new molecular targets and to improve the quantitative nature of PET experiments

  2. Bone formation rather than inflammation reflects ankylosing spondylitis activity on PET-CT: a pilot study.

    Science.gov (United States)

    Bruijnen, Stefan T G; van der Weijden, Mignon A C; Klein, Joannes P; Hoekstra, Otto S; Boellaard, Ronald; van Denderen, J Christiaan; Dijkmans, Ben A C; Voskuyl, Alexandre E; van der Horst-Bruinsma, Irene E; van der Laken, Conny J

    2012-04-02

    Positron Emission Tomography - Computer Tomography (PET-CT) is an interesting imaging technique to visualize Ankylosing Spondylitis (AS) activity using specific PET tracers. Previous studies have shown that the PET tracers [18F]FDG and [11C](R)PK11195 can target inflammation (synovitis) in rheumatoid arthritis (RA) and may therefore be useful in AS. Another interesting tracer for AS is [18F]Fluoride, which targets bone formation. In a pilot setting, the potential of PET-CT in imaging AS activity was tested using different tracers, with Magnetic Resonance Imaging (MRI) and conventional radiographs as reference. In a stepwise approach different PET tracers were investigated. First, whole body [18F]FDG and [11C](R)PK11195 PET-CT scans were obtained of ten AS patients fulfilling the modified New York criteria. According to the BASDAI five of these patients had low and five had high disease activity. Secondly, an extra PET-CT scan using [18F]Fluoride was made of two additional AS patients with high disease activity. MRI scans of the total spine and sacroiliac joints were performed, and conventional radiographs of the total spine and sacroiliac joints were available for all patients. Scans and radiographs were visually scored by two observers blinded for clinical data. No increased [18F]FDG and [11C](R)PK11195 uptake was noticed on PET-CT scans of the first 10 patients. In contrast, MRI demonstrated a total of five bone edema lesions in three out of 10 patients. In the two additional AS patients scanned with [18F]Fluoride PET-CT, [18F]Fluoride depicted 17 regions with increased uptake in both vertebral column and sacroiliac joints. In contrast, [18F]FDG depicted only three lesions, with an uptake of five times lower compared to [18F]Fluoride, and again no [11C](R)PK11195 positive lesions were found. In these two patients, MRI detected nine lesions and six out of nine matched with the anatomical position of [18F]Fluoride uptake. Conventional radiographs showed structural

  3. Dual-gated cardiac PET-clinical feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Teraes, Mika; Kokki, Tommi; Noponen, Tommi; Hoppela, Erika; Sipilae, Hannu T.; Knuuti, Juhani [Turku PET Centre, PO BOX 52, Turku (Finland); Durand-Schaefer, Nicolas [General Electric Medical Systems, Buc (France); Pietilae, Mikko [Turku University Hospital, Department of Internal Medicine, Turku (Finland); Kiss, Jan [Turku University Hospital, Department of Surgery, Turku (Finland)

    2010-03-15

    Both respiratory and cardiac motions reduce image quality in myocardial imaging. For accurate imaging of small structures such as vulnerable coronary plaques, simultaneous cardiac and respiratory gating is warranted. This study tests the feasibility of a recently developed robust method for cardiac-respiratory gating. List-mode data with triggers from respiratory and cardiac cycles are rearranged into dual-gated segments and reconstructed with standard algorithms of a commercial PET/CT scanner. Cardiac gates were defined as three fixed phases and one variable diastolic phase. Chest motion was measured with a respiratory gating device and post-processed to determine gates. Preservation of quantification in dual-gated images was tested with an IEC whole-body phantom. Minipig and human studies were performed to evaluate the feasibility of the method. In minipig studies, a coronary catheter with radioactive tip was guided in coronary artery for in vivo and ex vivo acquisitions. Dual gating in humans with suspected cardiac disorders was performed using 18-F-FDG as a tracer. The method was found feasible for in vivo imaging and the radioactive catheter tip was better resolved in gated images. In human studies, the dual gating was found feasible and easy for clinical routine. Maximal movement of myocardial surface in cranio-caudal direction was over 20 mm. The shape of myocardium was clearly different between the gates and papillary muscles become more visible in diastolic images. The first clinical experiences using robust cardiac-respiratory dual gating are encouraging. Further testing in larger clinical populations using tracers designed especially for plaque imaging is warranted. (orig.)

  4. Dual-gated cardiac PET-clinical feasibility study

    International Nuclear Information System (INIS)

    Teraes, Mika; Kokki, Tommi; Noponen, Tommi; Hoppela, Erika; Sipilae, Hannu T.; Knuuti, Juhani; Durand-Schaefer, Nicolas; Pietilae, Mikko; Kiss, Jan

    2010-01-01

    Both respiratory and cardiac motions reduce image quality in myocardial imaging. For accurate imaging of small structures such as vulnerable coronary plaques, simultaneous cardiac and respiratory gating is warranted. This study tests the feasibility of a recently developed robust method for cardiac-respiratory gating. List-mode data with triggers from respiratory and cardiac cycles are rearranged into dual-gated segments and reconstructed with standard algorithms of a commercial PET/CT scanner. Cardiac gates were defined as three fixed phases and one variable diastolic phase. Chest motion was measured with a respiratory gating device and post-processed to determine gates. Preservation of quantification in dual-gated images was tested with an IEC whole-body phantom. Minipig and human studies were performed to evaluate the feasibility of the method. In minipig studies, a coronary catheter with radioactive tip was guided in coronary artery for in vivo and ex vivo acquisitions. Dual gating in humans with suspected cardiac disorders was performed using 18-F-FDG as a tracer. The method was found feasible for in vivo imaging and the radioactive catheter tip was better resolved in gated images. In human studies, the dual gating was found feasible and easy for clinical routine. Maximal movement of myocardial surface in cranio-caudal direction was over 20 mm. The shape of myocardium was clearly different between the gates and papillary muscles become more visible in diastolic images. The first clinical experiences using robust cardiac-respiratory dual gating are encouraging. Further testing in larger clinical populations using tracers designed especially for plaque imaging is warranted. (orig.)

  5. Anatomical and functional volume concordance between FDG PET, and T2 and diffusion-weighted MRI for cervical cancer: a hybrid PET/MR study

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hongzan; Xin, Jun; Zhang, Shaomin; Guo, Qiyong; Lu, Yueyue; Zhai, Wei; Zhao, Long [Shengjing Hospital of China Medical University, Department of Radiology, Shenyang, Liaoning (China); Peng, Weiai [NM Marketing, Great China, Philips Healthcare, Guangzhou (China); Wang, Baijun [Philips China Investment Co. Ltd. Shenyang Office, Shenyang, Liaoning (China)

    2014-05-15

    To evaluate the concordance among {sup 18}F-FDG PET imaging, MR T2-weighted (T2-W) imaging and apparent diffusion coefficient (ADC) maps with diffusion-weighted (DW) imaging in cervical cancer using hybrid whole-body PET/MR. This study prospectively included 35 patients with cervical cancer who underwent pretreatment {sup 18}F-FDG PET/MR imaging. {sup 18}F-FDG PET and MR images were fused using standard software. The percent of the maximum standardized uptake values (SUV{sub max}) was used to contour tumours on PET images, and volumes were calculated automatically. Tumour volumes measured on T2-W and DW images were calculated with standard techniques of tumour area multiplied by the slice profile. Parametric statistics were used for data analysis. FDG PET tumour volumes calculated using SUV{sub max} (14.30 ± 4.70) and T2-W imaging volume (33.81 ± 27.32 cm{sup 3}) were similar (P > 0.05) at 35 % and 40 % of SUV{sub max} (32.91 ± 18.90 cm{sup 3} and 27.56 ± 17.19 cm{sup 3} respectively) and significantly correlated (P < 0.001; r = 0.735 and 0.766). The mean DW volume was 30.48 ± 22.41 cm{sup 3}. DW volumes were not significantly different from FDG PET volumes at either 35 % SUV{sub max} or 40 % SUV{sub max} or from T2-W imaging volumes (P > 0.05). PET subvolumes with increasing SUV{sub max} cut-off percentage showed an inverse change in mean ADC values on DW imaging (P < 0.001, ANOVA). Hybrid PET/MR showed strong volume concordance between FDG PET, and T2-W and DW imaging in cervical cancer. Cut-off at 35 % or 40 % of SUV{sub max} is recommended for {sup 18}F-FDG PET/MR SUV-based tumour volume estimation. The linear tumour subvolume concordance between FDG PET and DW imaging demonstrates individual regional concordance of metabolic activity and cell density. (orig.)

  6. Lesion concordance, image quality and artefacts in PET/CT. Results of a multicenter study

    International Nuclear Information System (INIS)

    Stergar, H.; Bockisch, A.; Krause, B.J.; Eschmann, S.M.; Juergens, K.U.; Kuehl, H.; Pfannenberg, A.C.; Stollfuss, J.; Weckesser, M.

    2010-01-01

    This study had three major objectives: (1.) to record the number of concordant (both in PET and CT) pathological lesions in different body regions/organs, (2.) to evaluate the image quality and (3.) to determine both, the quantity and the quality of artefacts in whole body FDG PET/CT scans. Routine whole body scans of 353 patients referred to FDG-PET/CT exams at 4 university hospitals were employed. All potentially malignant lesions in 13 different body regions/organs were classified as either concordant or suspicious in FDG-PET or CT only. In the latter case the diagnostic relevance of this disparity was judged. The image quality in PET and CT was rated as a whole and separately in 5 different body regions. Furthermore we investigated the frequency and site of artefacts caused by metal implants and oral or intravenous contrast media as well as the subjective co-registration quality (in 4 body regions) and the diagnostic impact of such artefacts or misalignment. In addition, the readers rated the diagnostic gain of adding the information from the other tomographic method. In total 1941 lesions (5.5 per patient) were identified, 1094 (56%) out of which were concordant. 602 (71%) out of the 847 remaining lesions were detected only with CT, 245 (29%) were only PET-positive. As expected, CT particularly depicted the majority of lesions in the lungs and abdominal organs. However, the diagnostic relevance was greater with PET-only positive lesions. Most of the PET/CT scans were performed with full diagnostic CT including administration of oral and intravenous contast media (> 80%). The image quality in PET and CT was rated excellent. Artefacts occurred in more than 60% of the scans and were mainly due to (dental) metal implants and contrast agent. Nevertheless there was almost no impact on diagnostic confidence if reading of the non attenuation corrected PET was included. The co-registration quality in general was also rated as excellent. Misalignment mostly occurred due

  7. Neural mechanisms of voluntary and involuntary recall: a PET study.

    Science.gov (United States)

    Hall, Nicoline Marie; Gjedde, Albert; Kupers, Ron

    2008-01-25

    Neuropsychological and neuroimaging studies on episodic memory retrieval have primarily focused on volitional memory tasks. However, some conscious memories arise involuntarily, i.e. without a strategic retrieval attempt, yet little is known about the neural network underlying involuntary episodic memory. The aim of this study was to determine whether voluntary and involuntary recall are mediated by separate cortical networks. We used positron emission tomography (PET) to measure changes in regional cerebral blood flow (rCBF) in 12 healthy subjects during voluntary and involuntary cued recall of pictures and a control condition with no episodic memory requirements. Involuntary recall was elicited by using an incidental memory task. Compared to the control condition, voluntary and involuntary recall were both associated with significant regional cerebral blood flow (rCBF) increases in posterior cingulate gyrus (PCG; BA 23), left precuneus (BA 7), and right parahippocampal gyrus (BA 35/36). In addition, rCBF in right dorsolateral prefrontal cortex (PFC; BA 8/9) and left precuneus (BA 7) was significantly larger during voluntary compared to involuntary recall, while rCBF was enhanced in left dorsolateral PFC (BA 9) during involuntary recall. The findings corroborate an association of the right PFC with a strategic component of episodic memory retrieval. Moreover, they show for the first time that it is possible to activate the medial temporal lobe, the PCG, and the precuneus, regions normally associated with retrieval success, without this strategic element. The relatively higher activity in precuneus during voluntary compared to involuntary recall suggests that activity in this region co-varies not only with retrieval success but also with retrieval intentionality.

  8. Clinical utility of FDG PET/CT in acute complicated pyelonephritis - results from an observational study

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Chih-Hsing [Mackay Memorial Hospital at Taipei, Department of Nuclear Medicine, Taipei (China); Tseng, Jing-Ren; Yen, Tzu-Chen [Chang Gung Memorial Hospital at Linkou, Department of Nuclear Medicine and Center for Advanced Molecular Imaging and Translation, Taoyuan (China); Chang Gung University, Department of Medical Imaging and Radiological Science, College of Medicine, Taoyuan (China); Lee, Ming-Hsun [Chang Gung Memorial Hospital at Linkou, Division of Infectious Diseases, Department of Internal Medicine, Taoyuan (China); Yang, Lan-Yan [Chang Gung Memorial Hospital at Linkou, Biostatistics Unit, Clinical Trial Center, Taoyuan (China)

    2018-03-15

    Acute complicated pyelonephritis (ACP) is an upper urinary tract infection associated with coexisting urinary tract abnormalities or medical conditions that could predispose to serious outcomes or treatment failures. Although CT and magnetic resonance imaging (MRI) are frequently used in patients with ACP, the clinical value of {sup 18}F-fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) has not been systematically investigated. This single-center retrospective study was designed to evaluate the potential usefulness of FDG PET/CT in patients with ACP. Thirty-one adult patients with ACP who underwent FDG PET/CT were examined. FDG PET/CT imaging characteristics, including tracer uptake patterns, kidney volumes, and extrarenal imaging findings, were reviewed in combination with clinical data and conventional imaging results. Of the 31 patients, 19 (61%) showed focal FDG uptake. The remaining 12 study participants showed a diffuse FDG uptake pattern. After volumetric approximation, the affected kidneys were found to be significantly enlarged. Patients who showed a focal uptake pattern had a higher frequency of abscess formation requiring drainage. ACP patients showing diffuse tracer uptake patterns had a more benign clinical course. Seven patients had suspected extrarenal coinfections, and FDG PET/CT successfully confirmed the clinical suspicion in five cases. FDG PET/CT was as sensitive as CT in identifying the six patients (19%) who developed abscesses. Notably, FDG PET/CT findings caused a modification to the initial antibiotic regimen in nine patients (29%). FDG PET/CT may be clinically useful in the assessment of patients with ACP who have a progressive disease course. (orig.)

  9. EANM/EARL harmonization strategies in PET quantification: from daily practice to multicentre oncological studies

    Energy Technology Data Exchange (ETDEWEB)

    Aide, Nicolas [University Hospital, Nuclear Medicine Department, Caen (France); Caen University, Inserm U1086 ANTICIPE, Caen (France); Lasnon, Charline [Caen University, Inserm U1086 ANTICIPE, Caen (France); Francois Baclesse Cancer Centre, Nuclear Medicine Department, Caen (France); Veit-Haibach, Patrick [University Hospital Zurich, Department of Nuclear Medicine and Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); University Health Network, University of Toronto, Joint Department Medical Imaging, Toronto (Canada); Sera, Terez [University of Szeged, Nuclear Medicine Department, Szeged (Hungary); Sattler, Bernhard [University Hospital of Leipzig, Department of Nuclear Medicine, Leipzig (Germany); Boellaard, Ronald [University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen (Netherlands); VU University Medical Center, Department of Radiology and Nuclear Medicine, Amsterdam (Netherlands)

    2017-08-15

    Quantitative positron emission tomography/computed tomography (PET/CT) can be used as diagnostic or prognostic tools (i.e. single measurement) or for therapy monitoring (i.e. longitudinal studies) in multicentre studies. Use of quantitative parameters, such as standardized uptake values (SUVs), metabolic active tumor volumes (MATVs) or total lesion glycolysis (TLG), in a multicenter setting requires that these parameters be comparable among patients and sites, regardless of the PET/CT system used. This review describes the motivations and the methodologies for quantitative PET/CT performance harmonization with emphasis on the EANM Research Ltd. (EARL) Fluorodeoxyglucose (FDG) PET/CT accreditation program, one of the international harmonization programs aiming at using FDG PET as a quantitative imaging biomarker. In addition, future accreditation initiatives will be discussed. The validation of the EARL accreditation program to harmonize SUVs and MATVs is described in a wide range of tumor types, with focus on therapy assessment using either the European Organization for Research and Treatment of Cancer (EORTC) criteria or PET Evaluation Response Criteria in Solid Tumors (PERCIST), as well as liver-based scales such as the Deauville score. Finally, also presented in this paper are the results from a survey across 51 EARL-accredited centers reporting how the program was implemented and its impact on daily routine and in clinical trials, harmonization of new metrics such as MATV and heterogeneity features. (orig.)

  10. Toward implementing an MRI-based PET attenuation-correction method for neurologic studies on the MR-PET brain prototype.

    Science.gov (United States)

    Catana, Ciprian; van der Kouwe, Andre; Benner, Thomas; Michel, Christian J; Hamm, Michael; Fenchel, Matthias; Fischl, Bruce; Rosen, Bruce; Schmand, Matthias; Sorensen, A Gregory

    2010-09-01

    Several factors have to be considered for implementing an accurate attenuation-correction (AC) method in a combined MR-PET scanner. In this work, some of these challenges were investigated, and an AC method based entirely on the MRI data obtained with a single dedicated sequence was developed and used for neurologic studies performed with the MR-PET human brain scanner prototype. The focus was on the problem of bone-air segmentation, selection of the linear attenuation coefficient for bone, and positioning of the radiofrequency coil. The impact of these factors on PET data quantification was studied in simulations and experimental measurements performed on the combined MR-PET scanner. A novel dual-echo ultrashort echo time (DUTE) MRI sequence was proposed for head imaging. Simultaneous MR-PET data were acquired, and the PET images reconstructed using the proposed DUTE MRI-based AC method were compared with the PET images that had been reconstructed using a CT-based AC method. Our data suggest that incorrectly accounting for the bone tissue attenuation can lead to large underestimations (>20%) of the radiotracer concentration in the cortex. Assigning a linear attenuation coefficient of 0.143 or 0.151 cm(-1) to bone tissue appears to give the best trade-off between bias and variability in the resulting images. Not identifying the internal air cavities introduces large overestimations (>20%) in adjacent structures. On the basis of these results, the segmented CT AC method was established as the silver standard for the segmented MRI-based AC method. For an integrated MR-PET scanner, in particular, ignoring the radiofrequency coil attenuation can cause large underestimations (i.e., PET field of view has to be accurately known. High-quality bone-air segmentation can be performed using the DUTE data. The PET images obtained using the DUTE MRI- and CT-based AC methods compare favorably in most of

  11. SU-E-J-270: Study of PET Response to HDR Brachytherapy of Rectal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, R; Le, Y; Armour, E; Efron, J; Azad, N; Wahl, R; Gearhart, S; Herman, J [Johns Hopkins University, Baltimore, MD (United States)

    2014-06-01

    Purpose: Dose-response studies in radiation therapy are typically using single response values for tumors across ensembles of tumors. Using the high dose rate (HDR) treatment plan dose grid and pre- and post-therapy FDG-PET images, we look for correlations between voxelized dose and FDG uptake response in individual tumors. Methods: Fifteen patients were treated for localized rectal cancer using 192Ir HDR brachytherapy in conjunction with surgery. FDG-PET images were acquired before HDR therapy and 6–8 weeks after treatment (prior to surgery). Treatment planning was done on a commercial workstation and the dose grid was calculated. The two PETs and the treatment dose grid were registered to each other using non-rigid registration. The difference in PET SUV values before and after HDR was plotted versus absorbed radiation dose for each voxel. The voxels were then separated into bins for every 400 cGy of absorbed dose and the bin average values plotted similarly. Results: Individual voxel doses did not correlate with PET response; however, when group into tumor subregions corresponding to dose bins, eighty percent of the patients showed a significant positive correlation (R2 > 0) between PET uptake difference in the targeted region and the absorbed dose. Conclusion: By considering larger ensembles of voxels, such as organ average absorbed dose or the dose bins considered here, valuable information may be obtained. The dose-response correlations as measured by FDG-PET difference potentially underlines the importance of FDG-PET as a measure of response, as well as the value of voxelized information.

  12. Dynamic respiratory gated 18FDG-PET of lung tumors - a feasibility study

    International Nuclear Information System (INIS)

    Skjei Knudtsen, Ingerid; Skretting, Arne; Roedal, Jan; Brustugun, Odd Terje; Helland, Aaslaug; Malinen, Eirik

    2011-01-01

    Background. 18 FDG-PET/CT imaging is well established for diagnosis and staging of lung tumors. However, more detailed information regarding the distribution of FDG within the tumor, also as a function of time after injection may be relevant. In this study we explore the feasibility of a combined dynamic and respiratory gated (DR) PET protocol. Material and methods. A DR FDG-PET protocol for a Siemens Biograph 16 PET/CT scanner was set up, allowing data acquisition from the time of FDG injection. Breath-hold (BH) respiratory gating was performed at four intervals over a total acquisition time of 50 minutes. Thus, the PET protocol provides both motion-free images and a spatiotemporal characterization of the glucose distribution in lung tumors. Software tools were developed in-house for tentative tumor segmentation and for extracting standard uptake values (SUVs) voxel by voxel, tumor volumes and SUV gradients in all directions. Results. Four pilot patients have been investigated with the DR PET protocol. The procedure was well tolerated by the patients. The BH images appeared sharper, and SUV max /SUV mean was higher, compared to free breathing (FB) images. Also, SUV gradients in the periphery of the tumor in the BH images were in general greater than or equal to the gradients in the FB PET images. Conclusion. The DR FDG-PET protocol is feasible and the BH images have a superior quality compared to the FB images. The protocol may also provide information of relevance for radiotherapy planning and follow-up. A patient trial is needed for assessing the clinical value of the imaging protocol

  13. Improved quantitation and reproducibility in multi-PET/CT lung studies by combining CT information.

    Science.gov (United States)

    Holman, Beverley F; Cuplov, Vesna; Millner, Lynn; Endozo, Raymond; Maher, Toby M; Groves, Ashley M; Hutton, Brian F; Thielemans, Kris

    2018-06-05

    Matched attenuation maps are vital for obtaining accurate and reproducible kinetic and static parameter estimates from PET data. With increased interest in PET/CT imaging of diffuse lung diseases for assessing disease progression and treatment effectiveness, understanding the extent of the effect of respiratory motion and establishing methods for correction are becoming more important. In a previous study, we have shown that using the wrong attenuation map leads to large errors due to density mismatches in the lung, especially in dynamic PET scans. Here, we extend this work to the case where the study is sub-divided into several scans, e.g. for patient comfort, each with its own CT (cine-CT and 'snap shot' CT). A method to combine multi-CT information into a combined-CT has then been developed, which averages the CT information from each study section to produce composite CT images with the lung density more representative of that in the PET data. This combined-CT was applied to nine patients with idiopathic pulmonary fibrosis, imaged with dynamic 18 F-FDG PET/CT to determine the improvement in the precision of the parameter estimates. Using XCAT simulations, errors in the influx rate constant were found to be as high as 60% in multi-PET/CT studies. Analysis of patient data identified displacements between study sections in the time activity curves, which led to an average standard error in the estimates of the influx rate constant of 53% with conventional methods. This reduced to within 5% after use of combined-CTs for attenuation correction of the study sections. Use of combined-CTs to reconstruct the sections of a multi-PET/CT study, as opposed to using the individually acquired CTs at each study stage, produces more precise parameter estimates and may improve discrimination between diseased and normal lung.

  14. Twelve automated thresholding methods for segmentation of PET images: a phantom study

    International Nuclear Information System (INIS)

    Prieto, Elena; Peñuelas, Iván; Martí-Climent, Josep M; Lecumberri, Pablo; Gómez, Marisol; Pagola, Miguel; Bilbao, Izaskun; Ecay, Margarita

    2012-01-01

    Tumor volume delineation over positron emission tomography (PET) images is of great interest for proper diagnosis and therapy planning. However, standard segmentation techniques (manual or semi-automated) are operator dependent and time consuming while fully automated procedures are cumbersome or require complex mathematical development. The aim of this study was to segment PET images in a fully automated way by implementing a set of 12 automated thresholding algorithms, classical in the fields of optical character recognition, tissue engineering or non-destructive testing images in high-tech structures. Automated thresholding algorithms select a specific threshold for each image without any a priori spatial information of the segmented object or any special calibration of the tomograph, as opposed to usual thresholding methods for PET. Spherical 18 F-filled objects of different volumes were acquired on clinical PET/CT and on a small animal PET scanner, with three different signal-to-background ratios. Images were segmented with 12 automatic thresholding algorithms and results were compared with the standard segmentation reference, a threshold at 42% of the maximum uptake. Ridler and Ramesh thresholding algorithms based on clustering and histogram-shape information, respectively, provided better results that the classical 42%-based threshold (p < 0.05). We have herein demonstrated that fully automated thresholding algorithms can provide better results than classical PET segmentation tools. (paper)

  15. Novel porcine repetitive elements

    Directory of Open Access Journals (Sweden)

    Nonneman Dan J

    2006-12-01

    Full Text Available Abstract Background Repetitive elements comprise ~45% of mammalian genomes and are increasingly known to impact genomic function by contributing to the genomic architecture, by direct regulation of gene expression and by affecting genomic size, diversity and evolution. The ubiquity and increasingly understood importance of repetitive elements contribute to the need to identify and annotate them. We set out to identify previously uncharacterized repetitive DNA in the porcine genome. Once found, we characterized the prevalence of these repeats in other mammals. Results We discovered 27 repetitive elements in 220 BACs covering 1% of the porcine genome (Comparative Vertebrate Sequencing Initiative; CVSI. These repeats varied in length from 55 to 1059 nucleotides. To estimate copy numbers, we went to an independent source of data, the BAC-end sequences (Wellcome Trust Sanger Institute, covering approximately 15% of the porcine genome. Copy numbers in BAC-ends were less than one hundred for 6 repeat elements, between 100 and 1000 for 16 and between 1,000 and 10,000 for 5. Several of the repeat elements were found in the bovine genome and we have identified two with orthologous sites, indicating that these elements were present in their common ancestor. None of the repeat elements were found in primate, rodent or dog genomes. We were unable to identify any of the replication machinery common to active transposable elements in these newly identified repeats. Conclusion The presence of both orthologous and non-orthologous sites indicates that some sites existed prior to speciation and some were generated later. The identification of low to moderate copy number repetitive DNA that is specific to artiodactyls will be critical in the assembly of livestock genomes and studies of comparative genomics.

  16. A cross-linguistic study of real-word and non-word repetition as predictors of grammatical competence in children with typical language development.

    Science.gov (United States)

    Dispaldro, Marco; Deevy, Patricia; Altoé, Gianmarco; Benelli, Beatrice; Leonard, Laurence B

    2011-01-01

    Although relationships among non-word repetition, real-word repetition and grammatical ability have been documented, it is important to study whether the specific nature of these relationships is tied to the characteristics of a given language. The aim of this study is to explore the potential cross-linguistic differences (Italian and English) in the relationship among non-word repetition, real-word repetition, and grammatical ability in three-and four-year-old children with typical language development. To reach this goal, two repetition tasks (one real-word list and one non-word list for each language) were used. In Italian the grammatical categories were the third person plural inflection and the direct-object clitic pronouns, while in English they were the third person singular present tense inflection and the past tense in regular and irregular forms. A cross-linguistic comparison showed that in both Italian and English, non-word repetition was a significant predictor of grammatical ability. However, performance on real-word repetition explained children's grammatical ability in Italian but not in English. Abilities underlying non-word repetition performance (e.g., the processing and/or storage of phonological material) play an important role in the development of children's grammatical abilities in both languages. Lexical ability (indexed by real-word repetition) showed a close relationship to grammatical ability in Italian but not in English. Implications of the findings are discussed in terms of cross-linguistic differences, genetic research, clinical intervention and methodological issues. © 2011 Royal College of Speech & Language Therapists.

  17. A cross-linguistic study of real-word and non-word repetition as predictors of grammatical competence in children with typical language development

    Science.gov (United States)

    Dispaldro, Marco; Deevy, Patricia; Altoe, Gianmarco; Benelli, Beatrice; Leonard Purdue, Laurence B.

    2013-01-01

    Background Although relationships among non-word repetition, real-word repetition and grammatical ability have been documented, it is important to study whether the specific nature of these relationships is tied to the characteristics of a given language. Aims The aim of this study is to explore the potential cross-linguistic differences (Italian and English) in the relationship among non-word repetition, real-word repetition, and grammatical ability in three- and four-year-old children with typical language development. Methods & Procedures To reach this goal, two repetition tasks (one real-word list and one non-word list for each language) were used. In Italian the grammatical categories were the third person plural inflection and the direct-object clitic pronouns, while in English they were the third person singular present tense inflection and the past tense in regular and irregular forms. Outcomes & Results A cross-linguistic comparison showed that in both Italian and English, non-word repetition was a significant predictor of grammatical ability. However, performance on real-word repetition explained children’s grammatical ability in Italian but not in English. Conclusions & Implications Abilities underlying non-word repetition performance (e.g., the processing and/or storage of phonological material) play an important role in the development of children’s grammatical abilities in both languages. Lexical ability (indexed by real-word repetition) showed a close relationship to grammatical ability in Italian but not in English. Implications of the findings are discussed in terms of cross-linguistic differences, genetic research, clinical intervention and methodological issues. PMID:21899673

  18. Imaging results and TOF studies with axial PET detectors

    CERN Document Server

    Joram, Christian

    2013-01-01

    We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the held of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The Fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations ( <2 mm FWHM in all three coordinates over the complete held of view) and also demonstrated the ability to include Compton interactions (inter-cr...

  19. Towards tracer dose reduction in PET studies: Simulation of dose reduction by retrospective randomized undersampling of list-mode data.

    Science.gov (United States)

    Gatidis, Sergios; Würslin, Christian; Seith, Ferdinand; Schäfer, Jürgen F; la Fougère, Christian; Nikolaou, Konstantin; Schwenzer, Nina F; Schmidt, Holger

    2016-01-01

    Optimization of tracer dose regimes in positron emission tomography (PET) imaging is a trade-off between diagnostic image quality and radiation exposure. The challenge lies in defining minimal tracer doses that still result in sufficient diagnostic image quality. In order to find such minimal doses, it would be useful to simulate tracer dose reduction as this would enable to study the effects of tracer dose reduction on image quality in single patients without repeated injections of different amounts of tracer. The aim of our study was to introduce and validate a method for simulation of low-dose PET images enabling direct comparison of different tracer doses in single patients and under constant influencing factors. (18)F-fluoride PET data were acquired on a combined PET/magnetic resonance imaging (MRI) scanner. PET data were stored together with the temporal information of the occurrence of single events (list-mode format). A predefined proportion of PET events were then randomly deleted resulting in undersampled PET data. These data sets were subsequently reconstructed resulting in simulated low-dose PET images (retrospective undersampling of list-mode data). This approach was validated in phantom experiments by visual inspection and by comparison of PET quality metrics contrast recovery coefficient (CRC), background-variability (BV) and signal-to-noise ratio (SNR) of measured and simulated PET images for different activity concentrations. In addition, reduced-dose PET images of a clinical (18)F-FDG PET dataset were simulated using the proposed approach. (18)F-PET image quality degraded with decreasing activity concentrations with comparable visual image characteristics in measured and in corresponding simulated PET images. This result was confirmed by quantification of image quality metrics. CRC, SNR and BV showed concordant behavior with decreasing activity concentrations for measured and for corresponding simulated PET images. Simulation of dose

  20. A Performance Study on Synchronous and Asynchronous Update Rules for A Plug-In Direct Particle Swarm Repetitive Controller

    Directory of Open Access Journals (Sweden)

    Ufnalski Bartlomiej

    2014-12-01

    Full Text Available In this paper two different update schemes for the recently developed plug-in direct particle swarm repetitive controller (PDPSRC are investigated and compared. The proposed approach employs the particle swarm optimizer (PSO to solve in on-line mode a dynamic optimization problem (DOP related to the control task in the constant-amplitude constant-frequency voltage-source inverter (CACF VSI with an LC output filter. The effectiveness of synchronous and asynchronous update rules, both commonly used in static optimization problems (SOPs, is assessed and compared in the case of PDPSRC. The performance of the controller, when synthesized using each of the update schemes, is studied numerically.

  1. Specification and estimation of sources of bias affecting neurological studies in PET/MR with an anatomical brain phantom

    Energy Technology Data Exchange (ETDEWEB)

    Teuho, J., E-mail: jarmo.teuho@tyks.fi [Turku PET Centre, Turku (Finland); Johansson, J. [Turku PET Centre, Turku (Finland); Linden, J. [Turku PET Centre, Turku (Finland); Department of Mathematics and Statistics, University of Turku, Turku (Finland); Saunavaara, V.; Tolvanen, T.; Teräs, M. [Turku PET Centre, Turku (Finland)

    2014-01-11

    Selection of reconstruction parameters has an effect on the image quantification in PET, with an additional contribution from a scanner-specific attenuation correction method. For achieving comparable results in inter- and intra-center comparisons, any existing quantitative differences should be identified and compensated for. In this study, a comparison between PET, PET/CT and PET/MR is performed by using an anatomical brain phantom, to identify and measure the amount of bias caused due to differences in reconstruction and attenuation correction methods especially in PET/MR. Differences were estimated by using visual, qualitative and quantitative analysis. The qualitative analysis consisted of a line profile analysis for measuring the reproduction of anatomical structures and the contribution of the amount of iterations to image contrast. The quantitative analysis consisted of measurement and comparison of 10 anatomical VOIs, where the HRRT was considered as the reference. All scanners reproduced the main anatomical structures of the phantom adequately, although the image contrast on the PET/MR was inferior when using a default clinical brain protocol. Image contrast was improved by increasing the amount of iterations from 2 to 5 while using 33 subsets. Furthermore, a PET/MR-specific bias was detected, which resulted in underestimation of the activity values in anatomical structures closest to the skull, due to the MR-derived attenuation map that ignores the bone. Thus, further improvements for the PET/MR reconstruction and attenuation correction could be achieved by optimization of RAMLA-specific reconstruction parameters and implementation of bone to the attenuation template. -- Highlights: • Comparison between PET, PET/CT and PET/MR was performed with a novel brain phantom. • The performance of reconstruction and attenuation correction in PET/MR was studied. • A recently developed brain phantom was found feasible for PET/MR imaging. • Contrast reduction

  2. Assessing FDG-PET diagnostic accuracy studies to develop recommendations for clinical use in dementia.

    Science.gov (United States)

    Boccardi, Marina; Festari, Cristina; Altomare, Daniele; Gandolfo, Federica; Orini, Stefania; Nobili, Flavio; Frisoni, Giovanni B

    2018-04-30

    FDG-PET is frequently used as a marker of synaptic damage to diagnose dementing neurodegenerative disorders. We aimed to adapt the items of evidence quality to FDG-PET diagnostic studies, and assess the evidence available in current literature to assist Delphi decisions for European recommendations for clinical use. Based on acknowledged methodological guidance, we defined the domains, specific to FDG-PET, required to assess the quality of evidence in 21 literature searches addressing as many Population Intervention Comparison Outcome (PICO) questions. We ranked findings for each PICO and fed experts making Delphi decisions for recommending clinical use. Among the 1435 retrieved studies, most lacked validated measures of test performance, an adequate gold standard, and head-to-head comparison of FDG-PET and clinical diagnosis, and only 58 entered detailed assessment. Only two studies assessed the accuracy of the comparator (clinical diagnosis) versus any kind of gold-/reference-standard. As to the index-test (FDG-PET-based diagnosis), an independent gold-standard was available in 24% of the examined papers; 38% used an acceptable reference-standard (clinical follow-up); and 38% compared FDG-PET-based diagnosis only to baseline clinical diagnosis. These methodological limitations did not allow for deriving recommendations from evidence. An incremental diagnostic value of FDG-PET versus clinical diagnosis or lack thereof cannot be derived from the current literature. Many of the observed limitations may easily be overcome, and we outlined them as research priorities to improve the quality of current evidence. Such improvement is necessary to outline evidence-based guidelines. The available data were anyway provided to expert clinicians who defined interim recommendations.

  3. A real-time monitoring study of the personal dose received by a nuclear medicine technologist (NMT)administering FDG in a high patient throughout PET centre

    International Nuclear Information System (INIS)

    Wallace, A.; Hickson, K.; Bradley, J.

    2007-01-01

    Full text: With the increasing success and developing applications of PET-CT, especially in relation to Oncology I Staging, il is possible thai the number of PET scans may overtake traditional gamma camera scanning as the major scanning I procedure. This rapid growth in PET studies has already resulted in an increasing radiation exposure cost to NMT'. Previous I personnel dosimetry surveys by our group have established the increasing dose impacts of PET and PET-CT investigations Bo staff (7, 2).

  4. [Study of patients with prolonged fever with (18)F-FDG PET/CT].

    Science.gov (United States)

    Moragas, M; Cozar, M Puig; Buxeda, M; Soler, M; Riera, E; García, J R

    2015-01-01

    To review the findings on (18)F-FDG PET-CT in patients with fever of unknown origin lasting more than 7 days. This retrospective descriptive observational study included 93 (18)F-FDG PET-CT studies to detect a fever-causing focus done at three nuclear medicine centers from October 2006 through February 2014. A nuclear medicine specialist and a radiologist reviewed the images for foci of pathological uptake; another specialist's opinion resolved discrepancies. The findings on (18)F-FDG PET-CT studies were checked against clinical and/or histological findings. Abnormal (18)F-FDG uptake on PET-CT that could explain the cause of the fever was found in 52 (56%) of the 93 studies, and the cause of the fever was confirmed in 50 of these 52 studies. In the 50 cases in which the cause of the fever was confirmed, infection was the most common cause (54%), followed by noninfectious inflammatory disease (28%) and tumors (18%). (18)F-FDG PET-CT is useful in diagnosing the cause of prolonged febrile illness, so it might be practical to use it earlier in the diagnostic process. Copyright © 2014 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

  5. Automated evaluation of setup errors in carbon ion therapy using PET: Feasibility study

    International Nuclear Information System (INIS)

    Kuess, Peter; Hopfgartner, Johannes; Georg, Dietmar; Helmbrecht, Stephan; Fiedler, Fine; Birkfellner, Wolfgang; Enghardt, Wolfgang

    2013-01-01

    Purpose: To investigate the possibility of detecting patient mispositioning in carbon-ion therapy with particle therapy positron emission tomography (PET) in an automated image registration based manner. Methods: Tumors in the head and neck (H and N), pelvic, lung, and brain region were investigated. Biologically optimized carbon ion treatment plans were created with TRiP98. From these treatment plans, the reference β + -activity distributions were calculated using a Monte Carlo simulation. Setup errors were simulated by shifting or rotating the computed tomography (CT). The expected β + activity was calculated for each plan with shifts. Finally, the reference particle therapy PET images were compared to the “shifted” β + -activity distribution simulations using the Pearson's correlation coefficient (PCC). To account for different PET monitoring options the inbeam PET was compared to three different inroom scenarios. Additionally, the dosimetric effects of the CT misalignments were investigated. Results: The automated PCC detection of patient mispositioning was possible in the investigated indications for cranio-caudal shifts of 4 mm and more, except for prostate tumors. In the rather homogeneous pelvic region, the generated β + -activity distribution of the reference and compared PET image were too much alike. Thus, setup errors in this region could not be detected. Regarding lung lesions the detection strongly depended on the exact tumor location: in the center of the lung tumor misalignments could be detected down to 2 mm shifts while resolving shifts of tumors close to the thoracic wall was more challenging. Rotational shifts in the H and N and lung region of +6° and more could be detected using inroom PET and partly using inbeam PET. Comparing inroom PET to inbeam PET no obvious trend was found. However, among the inroom scenarios a longer measurement time was found to be advantageous. Conclusions: This study scopes the use of various particle therapy

  6. Sensory analysis of pet foods.

    Science.gov (United States)

    Koppel, Kadri

    2014-08-01

    Pet food palatability depends first and foremost on the pet and is related to the pet food sensory properties such as aroma, texture and flavor. Sensory analysis of pet foods may be conducted by humans via descriptive or hedonic analysis, pets via acceptance or preference tests, and through a number of instrumental analysis methods. Sensory analysis of pet foods provides additional information on reasons behind palatable and unpalatable foods as pets lack linguistic capabilities. Furthermore, sensory analysis may be combined with other types of information such as personality and environment factors to increase understanding of acceptable pet foods. Most pet food flavor research is proprietary and, thus, there are a limited number of publications available. Funding opportunities for pet food studies would increase research and publications and this would help raise public awareness of pet food related issues. This mini-review addresses current pet food sensory analysis literature and discusses future challenges and possibilities. © 2014 Society of Chemical Industry.

  7. Dual cardiac-respiratory gated PET: implementation and results from a feasibility study

    International Nuclear Information System (INIS)

    Martinez-Moeller, Axel; Zikic, Darko; Navab, Nassir; Botnar, Rene M.; Bundschuh, Ralph A.; Ziegler, Sibylle I.; Schwaiger, Markus; Nekolla, Stephan G.; Howe, William

    2007-01-01

    Spatial resolution in myocardial imaging is impaired by both cardiac and respiratory motion owing to motional blurring. We investigated the feasibility of a dual cardiac-respiratory gated positron emission tomography (PET) acquisition using a clinical PET/computer tomography (CT) scanner. We describe its implementation and present results on the respiratory motion observed. The correlation between diaphragmatic excursion measured by real-time magnetic resonance imaging (MRI) and the expansion of the chest measured with an elastic belt was studied in six subjects. PET list mode acquisitions were then performed in 12 patients, six of them injected with 13 N-ammonia and six with 18 F-FDG. In parallel, the ECG and respiratory signals of the patients were recorded and the list mode file correspondingly sorted using a dual gated approach. Respiratory motion of the heart was quantified by measuring the displacement between the inspiratory and expiratory images in the diastolic phase by means of intensity-based non-rigid image registration. The correlation between diaphragmatic excursion and expansion of the chest was excellent (R 2 = 0.91), validating the ability of the elastic belt to provide an adequate respiratory trigger. Respiratory signals corresponding to the chest expansion showed a large inter-patient variability, requiring adapted algorithms in order to define suitable respiratory gates. Dual gated PET series were successfully acquired for both groups of patients, showing better resolved myocardial walls. The average respiratory motion of the heart measured by PET was 4.8 mm, with its largest component in the craniocaudal direction. Moreover, a deformation of the heart with respiration was observed, with the inferior wall moving significantly more than the anterior. Dual gated cardiac PET studies were performed successfully and showed better resolved myocardial walls as compared with ungated acquisitions. The respiratory motion of the heart presented a

  8. Repetition and the Concept of Repetition

    Directory of Open Access Journals (Sweden)

    Arne Grøn

    2013-11-01

    Full Text Available This paper offers a description of the meaning of the category of repetition. Firstly, it is pointed out that Constantin uses repetition as a concept that means the creation of epochs; the passing from Greece to Modernity is accomplished distinguishing between recollection, a concept that looks back to the past, and repetition, a concept that looks forward to future. Secondly, it is showed that the category of repetition, as a religious category, relates with what Climacus calls “ethic despair” and with what Vigilius calls “second ethics”; it is through repetition that it can be understood that sin finds its place in ethics and these shows the tension between it and dogmatics. And thirdly, it is showed that the descovery of the new category of repetition is a rediscovery of what Kierkegaard calls category of spirit; repetition has for its object the individuality, and coming to be oneself is what Kierkegaard undertands as liberty. At the end of the paper it is questioned if the category of repetition is inconsistent with the book Repetition.

  9. A Pilot Study for the Feasibility of F-18 FLT-PET in Locally Advanced Breast Cancer: Comparison with F-18 FDG-PET

    International Nuclear Information System (INIS)

    Lee, Jai Hyuen; Kim, Euy Nyong; Hong, Il Ki

    2008-01-01

    The aim of this study was to investigate the feasibility of 3'-[F-18]fluoro-3'-deoxythymidine positron emission tomography(FLT-PET) for the detection of locally advanced breast cancer and to compare the degree of FLT and 2'-deoxy-2'-[F-18]fluoro-d-glucose(FDG) uptake in primary tumor, lymph nodes and other normal organs. The study subjects consisted of 22 female patients (mean age; 42±6 years) with biopsy-confirmed infiltrating ductal carcinoma between Aug 2005 and Nov 2006. We performed conventional imaging workup, FDG-PET and FLT PET/CT. Average tumor size measured by MRI was 7.2±3.4 cm. With visual analysis, Tumor and Lymph node uptakes of FLT and FDG were determined by calculation of standardized uptake value (SUV) and tumor to background (TB) ratio. We compared FLT tumor uptake with FDG tumor uptake. We also investigated the correlation between FLT tumor uptake and FDG tumor uptake and the concordant rate with lymph node uptakes of FLT and FDG. FLT and FDG uptakes of bone marrow and liver were measured to compare the biodistribution of each other. All tumor lesions were visually detected in both FLT-PET and FDG-PET. There was no significant correlation between maximal tumor size by MRI and SUVmax of FLT-PET or FDG-PET (p>0.05). SUVmax and SUV75 (average SUV within volume of interest using 75% isocontour) of FLT-PET were significantly lower than those of FDG-PET in primary tumor (SUVmax; 6.3±5.2 vs 8.3±4.9, p=0.02 / SUV75; 5.3±4.3 vs 6.9 4.2, p=0.02). There is significant moderate correlation between uptake of FLT and FDG in primary tumor (SUVmax; rho=0.450, p=0.04 / SUV75; rho=0.472, p=0.03). But, TB ratio of FLT-PET was higher than that of FDG-PET(11.7±7.7 vs 6.3±3.8, p=0.001). The concordant rate between FLT and FDG uptake of lymph node was reasonably good (33/34). The FLT SUVs of liver and bone marrow were 4.2±1.2 and 8.3±4.9. The FDG SUVs of liver and bone marrow were 1.8±0.4 and 1.6±0.4. The uptakes of FLT were lower than those of FDG, but all

  10. Evaluation of PET Scanner Performance in PET/MR and PET/CT Systems: NEMA Tests

    OpenAIRE

    Mustafa Demir; Türkay Toklu; Mohammad Abuqbeitah; Hüseyin Çetin; H. Sezer Sezgin; Nami Yeyin; Kerim Sönmezoğlu

    2018-01-01

    Objective: The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor. Methods: According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated...

  11. Evaluation of PET Scanner Performance in PET/MR and PET/CT Systems: NEMA Tests

    OpenAIRE

    Demir, Mustafa; Toklu, Türkay; Abuqbeitah, Mohammad; Çetin, Hüseyin; Sezgin, H. Sezer; Yeyin, Nami; Sönmezoğlu, Kerim

    2018-01-01

    Objective: The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor. Methods: According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated asp...

  12. Repetitive Questioning II

    Directory of Open Access Journals (Sweden)

    R. C. Hamdy MD

    2018-02-01

    Full Text Available Repetitive questioning is a major problem for caregivers, particularly taxing if they are unable to recognize and understand the reasons why their loved one keeps asking the same question over and over again. Caregivers may be tempted to believe that the patient does not even try to remember the answer given or is just getting obnoxious. This is incorrect. Repetitive questioning is due to the underlying disease: The patient’s short term memory is impaired and he is unable to register, encode, retain and retrieve the answer. If he is concerned about a particular topic, he will keep asking the same question over and over again. To the patient each time she asks the question, it is as if she asked it for the first time. Just answering repetitive questioning by providing repeatedly the same answer is not sufficient. Caregivers should try to identify the underlying cause for this repetitive questioning. In an earlier case study, the patient was concerned about her and her family’s safety and kept asking whether the doors are locked. In this present case study, the patient does not know how to handle the awkward situation he finds himself in. He just does not know what to do. He is not able to adjust to the new unexpected situation. So he repeatedly wants to reassure himself that he is not intruding by asking the same question over and over again. We discuss how the patient’s son-in-law could have avoided this situation and averted the catastrophic ending.

  13. Photophysical studies of PET based acridinedione dyes with globular protein: Bovine serum albumin

    International Nuclear Information System (INIS)

    Rajendran, Kumaran; Perumal, Ramamurthy

    2010-01-01

    Interaction of acridinedione dyes with model transport proteins, bovine serum albumin (BSA) in aqueous solution were investigated by fluorescence spectral studies. A fluorescence enhancement was observed on the addition of BSA to photoinduced electron transfer (PET) based acridinedione dyes, which posses C 6 H 4 (p-OCH 3 ) in the 9th position of the basic acridinedione ring. On the contrary, the addition of BSA to non-PET based acridinedione dyes with methyl or phenyl substitution in the 9th position does not result in any fluorescence enhancement. The enhancement in the fluorescence intensity is attributed to the suppression of PET process through space between -OCH 3 group and the acridinedione moiety is elucidated by steady state fluorescence measurements. The fluorescence anisotropy value (r) of 0.40 reveals that the motion of the dye molecule is highly constrained and is largely confined to the rigid microenvironment of the protein molecule. The binding constant (K) was found to be in the order of 6.0x10 3 [M] -1 , which implies the existence of hydrophobic interaction between the PET based dye and BSA. Time resolved fluorescence lifetime measurements reveal that the PET based acridinedione dye preferably binds in the hydrophobic interior of BSA.

  14. Positron range in tissue-equivalent materials: experimental microPET studies

    Science.gov (United States)

    Alva-Sánchez, H.; Quintana-Bautista, C.; Martínez-Dávalos, A.; Ávila-Rodríguez, M. A.; Rodríguez-Villafuerte, M.

    2016-09-01

    In this work an experimental investigation was carried out to study the effect that positron range has over positron emission tomography (PET) scans through measurements of the line spread function (LSF) in tissue-equivalent materials. Line-sources consisted of thin capillary tubes filled with 18F, 13N or 68Ga water-solution inserted along the axis of symmetry of cylindrical phantoms constructed with the tissue-equivalent materials: lung (inhale and exhale), adipose tissue, solid water, trabecular and cortical bone. PET scans were performed with a commercial small-animal PET scanner and image reconstruction was carried out with filtered-backprojection. Line-source distributions were analyzed using radial profiles taken on axial slices from which the spatial resolution was determined through the full-width at half-maximum, tenth-maximum, twentieth-maximum and fiftieth-maximum. A double-Gaussian model of the LSFs was used to fit experimental data which can be incorporated into iterative reconstruction methods. In addition, the maximum activity concentration in the line-sources was determined from reconstructed images and compared to the known values for each case. The experimental data indicates that positron range in different materials has a strong effect on both spatial resolution and activity concentration quantification in PET scans. Consequently, extra care should be taken when computing standard-uptake values in PET scans, in particular when the radiopharmaceutical is taken up by different tissues in the body, and more even so with high-energy positron emitters.

  15. A combined microdialysis and FDG-PET study of glucose metabolism in head injury.

    Science.gov (United States)

    Hutchinson, Peter J; O'Connell, Mark T; Seal, Alex; Nortje, Jurgens; Timofeev, Ivan; Al-Rawi, Pippa G; Coles, Jonathan P; Fryer, Timothy D; Menon, David K; Pickard, John D; Carpenter, Keri L H

    2009-01-01

    Microdialysis continuously monitors the chemistry of a small focal volume of the cerebral extracellular space. Positron emission tomography (PET) establishes metabolism of the whole brain but only for the scan's duration. This study's objective was to apply these techniques together, in patients with traumatic brain injury, to assess the relationship between microdialysis (extracellular glucose, lactate, pyruvate, and the lactate/pyruvate (L/P) ratio as a marker of anaerobic metabolism) and PET parameters of glucose metabolism using the glucose analogue [(18)F]-fluorodeoxyglucose (FDG). In particular, we aimed to determine the fate of glucose in terms of differential metabolism to pyruvate and lactate. Microdialysis catheters (CMA70 or CMA71) were inserted into the cerebral cortex of 17 patients with major head injury. Microdialysis was performed during FDG-PET scans with regions of interest for PET analysis defined by the location of the gold-tipped microdialysis catheter. Microdialysate analysis was performed on a CMA600 analyser. There was significant linear relationship between the PET-derived parameter of glucose metabolism (regional cerebral metabolic rate of glucose; CMRglc) and levels of lactate (r = 0.778, p glucose was metabolised to both lactate and pyruvate, but was not associated with an increase in the L/P ratio. This suggests an increase in glucose metabolism to both lactate and pyruvate, as opposed to a shift towards anaerobic metabolism.

  16. Bilateral Repetitive Transcranial Magnetic Stimulation Combined with Intensive Swallowing Rehabilitation for Chronic Stroke Dysphagia: A Case Series Study

    Directory of Open Access Journals (Sweden)

    Ryo Momosaki

    2014-03-01

    Full Text Available The purpose of this study was to clarify the safety and feasibility of a 6-day protocol of bilateral repetitive transcranial magnetic stimulation (rTMS combined with intensive swallowing rehabilitation for chronic poststroke dysphagia. In-hospital treatment was provided to 4 poststroke patients (age at treatment: 56-80 years; interval between onset of stroke and treatment: 24-37 months with dysphagia. Over 6 consecutive days, each patient received 10 sessions of rTMS at 3 Hz applied to the pharyngeal motor cortex bilaterally, followed by 20 min of intensive swallowing rehabilitation exercise. The swallowing function was evaluated by the Penetration Aspiration Scale (PAS, Modified Mann Assessment of Swallowing Ability (MMASA, Functional Oral Intake Scale (FOIS, laryngeal elevation delay time (LEDT and Repetitive Saliva-Swallowing Test (RSST on admission and at discharge. All patients completed the 6-day treatment protocol and none showed any adverse reactions throughout the treatment. The combination treatment improved laryngeal elevation delay time in all patients. Our proposed protocol of rTMS plus swallowing rehabilitation exercise seems to be safe and feasible for chronic stroke dysphagia, although its efficacy needs to be confirmed in a large number of patients.

  17. In-beam PET imaging for on-line adaptive proton therapy: an initial phantom study

    Science.gov (United States)

    Shao, Yiping; Sun, Xishan; Lou, Kai; Zhu, Xiaorong R.; Mirkovic, Dragon; Poenisch, Falk; Grosshans, David

    2014-07-01

    We developed and investigated a positron emission tomography (PET) system for use with on-line (both in-beam and intra-fraction) image-guided adaptive proton therapy applications. The PET has dual rotating depth-of-interaction measurable detector panels by using solid-state photomultiplier (SSPM) arrays and LYSO scintillators. It has a 44 mm diameter trans-axial and 30 mm axial field-of-view (FOV). A 38 mm diameter polymethyl methacrylate phantom was placed inside the FOV. Both PET and phantom axes were aligned with a collimated 179.2 MeV beam. Each beam delivered ˜50 spills (0.5 s spill and 1.5 s inter-spill time, 3.8 Gy at Bragg peak). Data from each beam were acquired with detectors at a given angle. Nine datasets for nine beams with detectors at nine different angles over 180° were acquired for full-tomographic imaging. Each dataset included data both during and 5 min after irradiations. The positron activity-range was measured from the PET image reconstructed from all nine datasets and compared to the results from simulated images. A 22Na disc-source was also imaged after each beam to monitor the PET system's performance. PET performed well except for slight shifts of energy photo-peak positions (<1%) after each beam, due mainly to the neutron exposure of SSPM that increased the dark-count noise. This minor effect was corrected offline with a shifting 350-650 keV energy window for each dataset. The results show a fast converging of activity-ranges measured by the prototype PET with high sensitivity and uniform resolution. Sub-mm activity-ranges were achieved with minimal 6 s acquisition time and three spill irradiations. These results indicate the feasibility of PET for intra-fraction beam-range verification. Further studies are needed to develop and apply a novel clinical PET system for on-line image-guided adaptive proton therapy.

  18. Impact of FDG PET on the management of TBC treatment. A pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Sathekge, M. [Dept. of Nuclear Medicine, Univ. of Pretoria (South Africa); Maes, A. [Dept. of Nuclear Medicine, AZ Groeninge, Kortrijk (Belgium); Dept. of Morphology and Medical Imaging, Univ. Hospital Leuven (Belgium); Kgomo, M. [Dept. of Internal Medicine, Louis Pasture Hospital, Pretoria (South Africa); Stoltz, A. [Dept. of Infectious Diseases, Univ. of Pretoria (South Africa); Pottel, H. [Subfaculty of Medicine, Catholic Univ. Leuven, Campus Kortrijk (Belgium); Wiele, C. van de [Dept. of Nuclear Medicine, Univ. Hospital Ghent (Belgium)

    2010-07-01

    The aim of this study is to assess the potential impact of double-phase FDG PET versus routine staging in HIV-negative patients suffering from tuberculosis. Patients, methods: 16 consecutive patients suffering from tuberculosis underwent contrast-enhanced CT and double-phase FDG PET imaging (45 min, 120 min). Early (E) and delayed (D) SUVmax values were determined for all identified lesions and % change in SUV calculated ({delta}SUV). Results: Seven patients presented with lung lesions on PET as well as CT (mean SUVmaxE 8.2), mean SUVmaxD 11.1, (p = 0.002), {delta}SUV 35%. In two patients, lesions were judged as non-active on CT. In nine patients, 18 sites of LN involvement were identified on both early and delayed FDG PET images (mean SUVmaxE 6.3, mean SUVmaxD 7.9, (p = 0.0001), {delta}SUV: 25%). 9 out of 18 sites of LN involvement, occurring in five patients, were missed on CT. In four of these five patients, sites of LN involvement were the only sites of extra-pulmonary involvement identified. In 6 out of 16 patients, pleural involvement was identified, respectively in 5 on FDG PET and in 6 on CT imaging (mean SUVmaxE 1.3, mean SUVmaxD 1.7, (p = 0.06), {delta}SUV 21%). In 4 patients, osseous involvement was identified by both FDG PET and CT (mean SUVmaxE 7.2, mean SUVmaxD 10.7, (p = 0,06), {delta}SUV 45%). Finally, in 3 patients, joint involvement was identified on both FDG PET as well as on CT imaging (mean SUVmaxE 4.7, mean SUVmaxD 5.2, {delta}SUV 23%). FDG PET did not identify CT-additional sites of involvement that would have resulted in a prolonged treatment. Conclusion: In HIV-negative patients suffering from tuberculosis, FDG PET images suggested a more extensive involvement by Mycobacterium tuberculosis when compared to contrast enhanced CT. (orig.)

  19. Blood perfusion in osteomyelitis studied with [15O]water PET in a juvenile porcine model

    DEFF Research Database (Denmark)

    Jødal, Lars; Nielsen, Ole L; Afzelius, Pia

    2017-01-01

    and not quantitative. Quantitative assessment of perfusion could aid in the selection of therapy. A non-invasive, quantitative way to study perfusion is dynamic [15O]water positron emission tomography (PET). We aim to demonstrate that the method can be used for measuring perfusion in OM lesions and hypothesize...... that perfusion will be less elevated in OM lesions than in soft tissue (ST) infection. The study comprised 11 juvenile pigs with haematogenous osteomyelitis induced by injection of Staphylococcus aureus into the right femoral artery 1 week before scanning (in one pig, 2 weeks). The pigs were dynamically PET...

  20. Redefining orthodontic space closure: sequential repetitive loading of the periodontal ligament--a clinical study.

    Science.gov (United States)

    Kalha, Anmol S; Kachiwala, Viral Ashok; Govardhan, Singatagere Nagaraj; McLaughlin, Richard P; Khurshaid, Syed Zameer

    2010-01-01

    To assess the rate of tooth movement, anchorage loss, root resorption, and alkaline phosphatase (ALP) activity in the gingival crevicular fluid (GCF) as a marker for bone remodeling during orthodontic space closure using two different mechanisms. Space closure was completed in 20 patients with extraction of all 4 premolars. Lateral cephalograms and radio-visiographs taken before (T1) and after (T2) space closure were assessed for anchorage loss and root resorption. Alkaline phosphatase levels were measured in 10 patients, which were divided into two groups of five each. Spaces were closed with a screw device in the first group and with active tie-backs in the second. Gingival crevicular fluid samples, collected at intervals, were assayed for alkaline phosphatase spectrophotometrically in each patient. The mean rate of tooth movement was 1.32 ± 0.22 mm/month. The mean amount of anchorage loss in the maxilla and mandible was 1.23 ± 0.60 mm and 1.08 ± 0.65 mm, respectively. Sixty (25%) roots showed no root resorption, while 180 (75%) roots displayed mild to moderate blunting of their apices. Gingival crevicular fluid-alkaline phosphatase level increased significantly from day 7 to day 28 in both groups, but significantly more in the screw retraction group (Pspace closure occurs more rapidly with sequential repetitive loading of the periodontal ligament than with conventional active tie-backs. This observation is in concurrence with a significant increase in the gingival crevicular fluid-alkaline phosphatase level. © 2010 BY QUINTESSENCE PUBLISHING CO, INC.

  1. Benzodiazepine receptor distribution and cerebral blood flow in early blindness. A PET study

    International Nuclear Information System (INIS)

    Mishina, Masahiro; Senda, Michio; Kiyosawa, Motohiro

    2000-01-01

    We studied benzodiazepine receptor (BZR) distribution, which is thought to be affected by neuronal density in the cerebral cortex, and CBF using [ 11 C]flumazenil and [ 15 O]water PET in early blind (EB) and in blindfold sighted control (SC) subjects. PET images were co-registered to the subject's MRI. Using SPM96, MRI images were normalized in the Talairach and Tournoux coordinate system, and accordingly MRI-registered PET images were spatially normalized. Statistical parametric maps were computed on a voxel-by-voxel basis, using the general linear model. CBF for EB was significantly larger in the Brodmann area 17 and 18, especially anterior area, than that for SC, while there was no significant difference in BZR distribution. Our BZR data suggest that the amount of neurons do not change due to early visual deprivation in the visual cortex, in spite of high CBF in visual cortex of EB subjects. (author)

  2. Clinical study of the image fusion between CT and FDG-PET in the head and neck region

    International Nuclear Information System (INIS)

    Shozushima, Masanori; Moriguchi, Hitoshi; Shoji, Satoru; Sakamaki, Kimio; Ishikawa, Yoshihito; Kudo, Keigo; Satoh, Masanobu

    1999-01-01

    Image fusion using PET and CT from the head and neck region was performed with the use of external markers on 7 patients with squamous cell carcinoma. The purpose of this study was to examine a resultant error and the clinical usefulness of image fusion. Patients had primary lesions of the tongue, the maxillary gingiva or the maxillary sinus. All patients underwent PET with FDG and CT to detect tumor sites. Of these 7 patients, diagnostic images and the clinical observation found 6 cases of regional lymph node metastasis of the neck. To ensure the anatomical detail of the PET images, small radioactive markers were placed on the philtrum and below both earlobes. The PET image and CT image were then overlapped on a computer. The image fusion of PET and CT was successfully performed on all patients. The superposition error of this method was examined between the PET and CT images. The accuracy of fit measured as the mean distance between the PET and CT image was in the range of 2-5 mm. PET-CT superimposed images produced an increase in the localization of tumor FDG uptake and localized FDG uptake on the palatine tonsils. The marker system described here for the alignment of PET and CT images can be used on a routine basis without the invasive fixation of external markers, and also improve the management and follow up on patients with head and neck carcinoma. (author)

  3. J-PET detector system for studies of the electron-positron annihilations

    Directory of Open Access Journals (Sweden)

    Pawlik-Niedźwiecka M.

    2016-01-01

    Full Text Available Jagiellonian Positron Emission Tomograph (J-PET has been recently constructed at the Jagiellonian University as a prototype of a cost-effective scanner for the metabolic imaging of the whole human body. J-PET detector is optimized for the measurement of momentum and polarization of photons from the electron-positron annihilations. It is built out of strips of plastic scintillators, forming three cylindrical layers. As detector of gamma quanta it will be used for studies of discrete symmetries and multiparticle entanglement of photons originating from the decays of ortho-positronium atoms.

  4. Pets in the home and the development of pet allergy in adulthood. The Copenhagen Allergy Study

    DEFF Research Database (Denmark)

    Linneberg, A; Nielsen, N H; Madsen, F

    2003-01-01

    BACKGROUND: The aim of the study was to investigate the association between exposure to cat and dog in the home and the development (incidence) of IgE sensitization to cat and dog. METHODS: Participants in a population-based study of 15-69-year-olds in 1990 were invited to a follow-up in 1998. Se...

  5. Design studies of a depth encoding large aperture PET camera

    International Nuclear Information System (INIS)

    Moisan, C.; Rogers, J.G.; Buckley, K.R.; Ruth, T.J.; Stazyk, M.W.; Tsang, G.

    1994-10-01

    The feasibility of a wholebody PET tomograph with the capacity to correct for the parallax error induced by the Depth-Of-Interaction of γ-rays is assessed through simulation. The experimental energy, depth, and transverse position resolutions of BGO block detector candidates are the main inputs to a simulation that predicts the point source resolution of the Depth Encoding Large Aperture Camera (DELAC). The results indicate that a measured depth resolution of 7 mm (FWHM) is sufficient to correct a substantial part of the parallax error for a point source at the edge of the Field-Of-View. A search for the block specifications and camera ring radius that would optimize the spatial resolution and its uniformity across the Field-Of-View is also presented. (author). 10 refs., 1 tab., 5 figs

  6. Weight Gain following Pallidal Deep Brain Stimulation: A PET Study.

    Directory of Open Access Journals (Sweden)

    Paul Sauleau

    Full Text Available The mechanisms behind weight gain following deep brain stimulation (DBS surgery seem to be multifactorial and suspected depending on the target, either the subthalamic nucleus (STN or the globus pallidus internus (GPi. Decreased energy expenditure following motor improvement and behavioral and/or metabolic changes are possible explanations. Focusing on GPi target, our objective was to analyze correlations between changes in brain metabolism (measured with PET and weight gain following GPi-DBS in patients with Parkinson's disease (PD. Body mass index was calculated and brain activity prospectively measured using 2-deoxy-2[18F]fluoro-D-glucose PET four months before and four months after the start of GPi-DBS in 19 PD patients. Dopaminergic medication was included in the analysis to control for its possible influence on brain metabolism. Body mass index increased significantly by 0.66 ± 1.3 kg/m2 (p = 0.040. There were correlations between weight gain and changes in brain metabolism in premotor areas, including the left and right superior gyri (Brodmann area, BA 6, left superior gyrus (BA 8, the dorsolateral prefrontal cortex (right middle gyrus, BAs 9 and 46, and the left and right somatosensory association cortices (BA 7. However, we found no correlation between weight gain and metabolic changes in limbic and associative areas. Additionally, there was a trend toward a correlation between reduced dyskinesia and weight gain (r = 0.428, p = 0.067. These findings suggest that, unlike STN-DBS, motor improvement is the major contributing factor for weight gain following GPi-DBS PD, confirming the motor selectivity of this target.

  7. Effects of ferumoxytol on quantitative PET measurements in simultaneous PET/MR whole-body imaging: a pilot study in a baboon model.

    Science.gov (United States)

    Borra, Ronald Jh; Cho, Hoon-Sung; Bowen, Spencer L; Attenberger, Ulrike; Arabasz, Grae; Catana, Ciprian; Josephson, Lee; Rosen, Bruce R; Guimaraes, Alexander R; Hooker, Jacob M

    2015-12-01

    Simultaneous PET/MR imaging depends on MR-derived attenuation maps (mu-maps) for accurate attenuation correction of PET data. Currently, these maps are derived from gradient-echo-based MR sequences, which are sensitive to susceptibility changes. Iron oxide magnetic nanoparticles have been used in the measurement of blood volume, tumor microvasculature, tumor-associated macrophages, and characterizing lymph nodes. Our aim in this study was to assess whether the susceptibility effects associated with iron oxide nanoparticles can potentially affect measured (18)F-FDG PET standardized uptake values (SUV) through effects on MR-derived attenuation maps. The study protocol was approved by the Institutional Animal Care and Use Committee. Using a Siemens Biograph mMR PET/MR scanner, we evaluated the effects of increasing concentrations of ferumoxytol and ferumoxytol aggregates on MR-derived mu-maps using an agarose phantom. In addition, we performed a baboon experiment evaluating the effects of a single i.v. ferumoxytol dose (10 mg/kg) on the liver, spleen, and pancreas (18)F-FDG SUV at baseline (ferumoxytol-naïve), within the first hour and at 1, 3, 5, and 11 weeks. Phantom experiments showed mu-map artifacts starting at ferumoxytol aggregate concentrations of 10 to 20 mg/kg. The in vivo baboon data demonstrated a 53% decrease of observed (18)F-FDG SUV compared to baseline within the first hour in the liver, persisting at least 11 weeks. A single ferumoxytol dose can affect measured SUV for at least 3 months, which should be taken into account when administrating ferumoxytol in patients needing sequential PET/MR scans. Advances in knowledge 1. Ferumoxytol aggregates, but not ferumoxytol alone, produce significant artifacts in MR-derived attenuation correction maps at approximate clinical dose levels of 10 mg/kg. 2. When performing simultaneous whole-body (18)F-FDG PET/MR, a single dose of ferumoxytol can result in observed SUV decreases up to 53%, depending on the

  8. Cerebral activation studies by PET and fMRT, clinical relevance?; Zerebrale Aktivierungsstudien mit PET und fMRT, klinische Relevanz?

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, T. [Neurologische Klinik und Poliklinik, Klinikum Grosshadern, Muenchen Univ. (Germany)

    1997-03-01

    Cerebral activation studies by PET and fMRT will gain increasing clinical relevance for functional neuroanatomy (reading, speaking), localisation of largely unknown cortical functions (vestibular cortex), imaging of subjective complaints of functional impairments (pain, smell, memory), and documentation of neurological rehabilitation at neuronal level (regeneration, compensation, substitution, learning). (orig.) [Deutsch] Zerebrale Aktivierungsstudien mit PET und fMRT erlangen zunehmend klinische Bedeutung fuer die funktionelle Neuroanatomie einzelner und komplexer Hirnleistungen (Lesen, Sprechen), die Lokalisation bislang unzureichend erforschter Hirnfunktionen (vestibulaerer Kortex), die Objektivierung subjektiver Beschwerden und Funktionsausfaelle (Schmerz, Riechen, Gedaechtnis) und die Dokumentation neurologischer Rehabilitation auf neuronaler Ebene (Regeneration, Kompensation, Substitution, Lernen). (orig.)

  9. Investigations on the effects of ``Ecstasy`` on cerebral glucose metabolism: an 18-FDG PET study; Untersuchungen zum Einfluss von ``Ecstasy`` auf den zerebralen Glukosemetabolismus: eine 18-FDG-PET-Studie

    Energy Technology Data Exchange (ETDEWEB)

    Schreckenberger, M.; Sabri, O.; Arning, C.; Tuttass, T.; Schulz, G.; Kaiser, H.J.; Wagenknecht, G.; Buell, U. [Klinik fuer Nuklearmedizin, Universitaetsklinik, RWTH Aachen (Germany); Gouzoulis-Mayfrank, E.; Sass, H. [Klinik fuer Psychiatrie, Universitaetsklinikum, RWTH Aachen (Germany)

    1998-12-31

    Purpose: The aim of the present study was to determine the acute effects of the `Ecstasy` analogue MDE (3,4-methylendioxyethamphetamine) on the cerebral glucose metabolism (rMRGlu) of healthy volunteers. Method: In a randomised double-blind trial, 16 healthy volunteers without a history of drug abuse were examined with 18-FDG PET 110-120 minutes after oral administration of 2 mg/kg MDE (n=8) or placebo (n=8). Beginning two minutes prior to radiotracer injection, a constant cognitive stimulation was maintained for 32 minutes using a word repetition paradigm in order to ensure constant and comparable mental conditions during cerebral 18-FDG uptake. Individual brain anatomy was represented using T1-weighted 3D flash MRI, followed by manual regionalisation into 108 regions-of-interest and PET/MRI overlay. Absolute quantification of rMRGlu and comparison of glucose metabolism under MDE versus placebo were performed using Mann-Whitney U-test. Results: Absolute global MRGlu was not significantly changed under MDE versus placebo (MDE: 41,8{+-}11,1 {mu}mol/min/100 g, placebo: 50,1{+-}18,1 {mu}mol/min/100 g, p=0,298). The normalised regional metabolic data showed a significantly decreased rMRGlu in the bilateral frontal cortex: Left frontal posterior (-7.1%, p<0.05) and right prefrontal superior (-4.6%, p<0.05). On the other hand, rMRGlu was significantly increased in the bilateral cerebellum (right: +10.1%, p<0.05; left: +7.6%, p<0.05) and in the right putamen (+6.2%, p<0.05). Conclusions: The present study revealed acute neurometabolic changes under the `Ecstasy` analogon MDE indicating a fronto-striato-cerebellar dysbalance with parallels to other psychotropic substances and various endogenous psychoses respectively. (orig.) [Deutsch] Ziel: In der vorliegenden Studie sollte die Akutwirkung des `Ecstasy`-Analogons MDE (3,4-Methylendioxyethamphetamin) auf den zentralen Glukosemetabolismus (rMRGlu) gesunder Probanden untersucht werden. Methode: In einer randomisierten

  10. Mechanisms of repetitive retrograde contractions in response to sustained esophageal distension: a study evaluating patients with postfundoplication dysphagia.

    Science.gov (United States)

    Carlson, Dustin A; Kahrilas, Peter J; Ritter, Katherine; Lin, Zhiyue; Pandolfino, John E

    2018-03-01

    Repetitive retrograde contractions (RRCs) in response to sustained esophageal distension are a distinct contractility pattern observed with functional luminal imaging probe (FLIP) panometry that are common in type III (spastic) achalasia. RRCs are hypothesized to be indicative of either impaired inhibitory innervation or esophageal outflow obstruction. We aimed to apply FLIP panometry to patients with postfundoplication dysphagia (a model of esophageal obstruction) to explore mechanisms behind RRCs. Adult patients with dysphagia after Nissen fundoplication ( n = 32) or type III achalasia ( n = 25) were evaluated with high-resolution manometry (HRM) and upper endoscopy with FLIP. HRM studies were assessed for outflow obstruction and spastic features: premature contractility, hypercontractility, and impaired deglutitive inhibition during multiple-rapid swallows. FLIP studies were analyzed to determine the esophagogastric junction (EGJ)-distensibility index and contractility pattern, including RRCs. Barium esophagram was evaluated when available. RRCs were present in 8/32 (25%) fundoplication and 19/25 (76%) achalasia patients ( P esophageal outflow obstruction, as a predictor for RRCs. RRCs in response to sustained esophageal distension appear to be a manifestation of spastic esophageal motility. Although future study to further clarify the significance of RRCs is needed, RRCs on FLIP panometry should prompt evaluation for a major motor disorder. NEW & NOTEWORTHY Repetitive retrograde contractions (RRCs) are a common response to sustained esophageal distension among spastic achalasia patients when evaluated with the functional luminal imaging probe. We evaluated patients with postfundoplication dysphagia, i.e., patients with suspected mechanical obstruction, and found that RRCs occasionally occurred among postfundoplication patients, but often in association with manometric features of esophageal neuromuscular imbalance. Thus, RRCs appear to be a manifestation of

  11. Imaging and PET - PET/CT imaging

    International Nuclear Information System (INIS)

    Von Schulthess, G.K.; Hany, Th.F.

    2008-01-01

    PET/CT has grown because the lack of anatomic landmarks in PET makes 'hardware-fusion' to anatomic cross-sectional data extremely useful. Addition of CT to PET improves specificity, but also sensitivity, and adding PET to CT adds sensitivity and specificity in tumor imaging. The synergistic advantage of adding CT is that the attenuation correction needed for PET data can also be derived from the CT data. This makes PET-CT 25-30% faster than PET alone, leading to higher patient throughput and a more comfortable examination for patients typically lasting 20 minutes or less. FDG-PET-CT appears to provide relevant information in the staging and therapy monitoring of many tumors, such as lung carcinoma, colorectal cancer, lymphoma, gynaecological cancers, melanoma and many others, with the notable exception of prostatic cancer. for this cancer, choline derivatives may possibly become useful radiopharmaceuticals. The published literature on the applications of FDG-PET-CT in oncology is still limited but several designed studies have demonstrated the benefits of PET-CT. (authors)

  12. MIMICRY, DIFFERENCE AND REPETITION

    Directory of Open Access Journals (Sweden)

    Marcelo Mendes de Souza

    2008-07-01

    Full Text Available This article addresses Homi K. Bhabha’s concept of mimicry in a broader context, other than that of cultural studies and post-colonial studies, bringing together other concepts, such as that of Gilles Deleuze in Difference and repetition, among other texts, and other names, such as Silviano Santiago, Jorge Luís Borges, Franz Kafka and Giorgio Agamben. As a partial conclusion, the article intends to oppose Bhabha’s freudian-marxist view to Five propositions on Psychoanalysis (1973, Gilles Deleuze’s text about Psychoanalysis published right after his book The Anti-Oedipus.

  13. Pets in the home and the development of pet allergy in adulthood. The Copenhagen Allergy Study

    DEFF Research Database (Denmark)

    Linneberg, A; Nielsen, N H; Madsen, F

    2003-01-01

    BACKGROUND: The aim of the study was to investigate the association between exposure to cat and dog in the home and the development (incidence) of IgE sensitization to cat and dog. METHODS: Participants in a population-based study of 15-69-year-olds in 1990 were invited to a follow-up in 1998....... Serum IgE antibodies against common inhalant allergens was assessed in 734 subjects (participation rate 69.0%) on two occasions 8 years apart. Information about current or previous keeping of cats and dogs in the home was obtained in a questionnaire at baseline. RESULTS: A cat in the home currently......E sensitization to cat. A dog in the home was not significantly associated with the development of IgE sensitization to dog. CONCLUSIONS: In this adult population, exposure to a cat in the home increased the risk of developing IgE sensitization to cat. More prospective data are needed on this issue....

  14. Influence of spinal cord injury on cerebral sensorimotor systems : A PET study

    NARCIS (Netherlands)

    Roelcke, U; Curt, A; Otte, A; Missimer, J; Maguire, RP; Dietz, [No Value; Leenders, KL

    Objectives-To assess the effect of a transverse spinal cord lesion on cerebral energy metabolism in view of sensorimotor reorganisation. Methods-PET and F-18-fluorodeoxyglucose were used to study resting cerebral glucose metabolism in 11 patients with complete paraplegia or tetraplegia after spinal

  15. Increased cerebral iron uptake in Wilson's disease : A (52)Fe-citrate PET study

    NARCIS (Netherlands)

    Bruehlmeier, M; Leenders, KL; Vontobel, P; Calonder, C; Antonini, A; Weindl, A

    Toxicity of abundant copper is the main cause of brain and liver tissue damage in patients with Wilson's disease (WD). However, there is also evidence of a disturbed iron metabolism in this genetically determined disorder. This PET study was undertaken to assess cerebral iron metabolism in WD

  16. Open-loop recycling: A LCA case study of PET bottle-to-fibre-recycling

    NARCIS (Netherlands)

    Shen, L.; Worrell, E.; Patel, M.K.

    2010-01-01

    This study assesses the environmental impact of polyethylene terephthalate (PET) bottle-to-fibre recycling using the methodology of life-cycle assessment (LCA). Four recycling cases, including mechanical recycling, semi-mechanical recycling, back-to-oligomer recycling and back-to-monomer recycling

  17. Cerebral activation studies by PET and fMRT, clinical relevance?

    International Nuclear Information System (INIS)

    Brandt, T.

    1997-01-01

    Cerebral activation studies by PET and fMRT will gain increasing clinical relevance for functional neuroanatomy (reading, speaking), localisation of largely unknown cortical functions (vestibular cortex), imaging of subjective complaints of functional impairments (pain, smell, memory), and documentation of neurological rehabilitation at neuronal level (regeneration, compensation, substitution, learning). (orig.) [de

  18. A PET study on cortical and subcortical control of pelvic floor musculature in women

    NARCIS (Netherlands)

    Blok, Bertil F.M.; Sturms, Leontien M.; Holstege, Gert

    1997-01-01

    The pelvic floor musculature plays an important role in behaviors such as defecation, micturition, mating behavior, and vomiting. A recent positron emission tomography (PET) study revealed that structures belonging to the emotional motor system are involved in the control of the pelvic floor during

  19. Integrating respiratory-gated PET-based target volume delineation in liver SBRT planning, a pilot study

    International Nuclear Information System (INIS)

    Riou, Olivier; Thariat, Juliette; Serrano, Benjamin; Azria, David; Paulmier, Benoit; Villeneuve, Remy; Fenoglietto, Pascal; Artenie, Antonella; Ortholan, Cécile; Faraggi, Marc

    2014-01-01

    To assess the feasibility and benefit of integrating four-dimensional (4D) Positron Emission Tomography (PET) – computed tomography (CT) for liver stereotactic body radiation therapy (SBRT) planning. 8 patients with 14 metastases were accrued in the study. They all underwent a non-gated PET and a 4D PET centered on the liver. The same CT scan was used for attenuation correction, registration, and considered the planning CT for SBRT planning. Six PET phases were reconstructed for each 4D PET. By applying an individualized threshold to the 4D PET, a Biological Internal Target Volume (BITV) was generated for each lesion. A gated Planning Target Volume (PTVg) was created by adding 3 mm to account for set-up margins. This volume was compared to a manual Planning Target Volume (PTV) delineated with the help of a semi-automatic Biological Target Volume (BTV) obtained from the non-gated exam. A 5 mm radial and a 10 mm craniocaudal margins were applied to account for tumor motion and set-up margins to create the PTV. One undiagnosed liver metastasis was discovered thanks to the 4D PET. The semi-automatic BTV were significantly smaller than the BITV (p = 0.0031). However, after applying adapted margins, 4D PET allowed a statistically significant decrease in the PTVg as compared to the PTV (p = 0.0052). In comparison to non-gated PET, 4D PET may better define the respiratory movements of liver targets and improve SBRT planning for liver metastases. Furthermore, non respiratory-gated PET exams can both misdiagnose liver metastases and underestimate the real internal target volumes

  20. On the fractal nature of dynamic positron emission tomography (PET) studies

    International Nuclear Information System (INIS)

    Dimitrakopoulou-Strauss, A.; Strauss, L.G.; Mikolajczyk, K.; Burger, C.; Lehnert, T.; Bernd, L.; Ewerbeck, V.

    2003-01-01

    Quantification of dynamic PET Studies is generally based on compartmental methods. This is a report about the implementation and assessment of a new non-compartmental method, the fractal dimension (FD), a parameter based on the box counting (BC) procedure of the chaos theory for the analysis of dynamic PET data. The evaluation included 200 malignant lesions in 159 patients with different tumour entities as well as 57 benign lesions for comparison. 101/200 malignant lesions were treated with chemotherapy, whereas 99/200 malignant lesions as well as all 57 benign lesions were untreated within the last six months prior to the PET study with F-18-Fluorodeoxyglucose (FDG). The evaluation of the FDG kinetics was performed using the BC based FD for the time-activity data. Visual assessment demonstrated generally different FDG uptake patterns in the conventional images and the parametric images of FD. FD estimates depended on the number of boxes and the maximum cut-off value used for calculation. Based on the discriminant analysis for benign and malignant lesions, FD demonstrated an accuracy of 76.65% for all patients, 67.7% for the untreated patients and 83.44% for the treated group. The use of the BC based FD is a reliable, new method for the quantification of dynamic PET studies and seems to be in particular helpful for the evaluation of treated malignant lesions. (author)

  1. Impact of F.D.G.-PET on radiation therapy: economic results of a STIC study

    International Nuclear Information System (INIS)

    Remonnay, R.; Morelle, M.; Pommier, P.; Carrere, M.O.; Giammaril, F.; Pommier, P.

    2009-01-01

    The aim of this study is to assess the effects of Positron Emission Tomography (PET) associated with computed tomography (CT) on resource allocation (costs and savings) of the following treatment in radiotherapy for non small cell lung cancers (N.S.C.L.C.) and Hodgkin's diseases. A national prospective study was conducted in nine hospitals. Two treatment decisions made on the basis of CT only or on PET associated with, were compared in a before-after design. The direct medical cost of using PET was assessed by micro-costing. The costs of new exams and the costs and savings associated with changes in the chosen treatment were calculated on the basis of reimbursement rates. The economic study was conducted over 2 years and included 209 patients (97 patients with Hodgkin's disease and 112 with N.S.C.L.C.). The mean cost of using PET, corresponding to an extra cost, was approximately 800 Euros (50% for the radionuclide F.D.G.). Radiotherapy treatments were modified for only 10% of patients with Hodgkin's disease with a minor impact on treatment costs versus 40% of patients with lung cancer with a reduction in mean treatment cost of more than 500 Euros. (authors)

  2. PET/CT assessment in follicular lymphoma using standardized criteria: central review in the PRIMA study

    Energy Technology Data Exchange (ETDEWEB)

    Tychyj-Pinel, Christelle [Service de Medecine Nucleaire, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre-Benite (France); Ricard, Fabien [Service de Medecine Nucleaire, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre-Benite (France); Universite de Lyon, Faculte de Medecine, UCB Lyon 1, Lyon (France); Fulham, Michael [Royal Prince Alfred Hospital, Department of PET and Nuclear Medicine, Sydney (Australia); University of Sydney, Sydney Medical School, Sydney (Australia); Fournier, Marion [Centre Hospitalier Lyon Sud, The Lymphoma Academic Research Organisation (LYSARC), Pierre-Benite (France); Meignan, Michel [CHU Henri Mondor, Medicine Nucleaire, Creteil (France); Lamy, Thierry [Service d' Hematologie, CHU, Rennes (France); Vera, Pierre [Centre Henri Becquerel, Service de Medecine Nucleaire, Rouen (France); Rouen University, QuantIF (Litis EA4108), Rouen (France); Salles, Gilles [Universite de Lyon, Faculte de Medecine, UCB Lyon 1, Lyon (France); Service d' Hematologie, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, Pierre-Benite (France); Trotman, Judith [University of Sydney, Sydney Medical School, Sydney (Australia); Concord Hospital, Department of Haematology, Concord, NSW (Australia)

    2014-03-15

    We aimed to compare the standardized central review of {sup 18}F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT scans performed after induction therapy for follicular lymphoma (FL) in the PRIMA study (Salles et al., Lancet 377:42-51, 2011; Trotman et al., J Clin Oncol 29:3194-3200, 2011) to scan review at local centres. PET/CT scans were independently evaluated by two nuclear medicine physicians using the 2007 International Harmonization Project (IHP) criteria (Cheson et al., J Clin Oncol 25:579-586, 2007; Juweid et al., J Clin Oncol 25:571-578, 2007; Shankar et al., J Nucl Med 47:1059-1066, 2006) and Deauville 5-point scale (5PS) criteria (Meignan et al., Leuk Lymphoma 50:1257-1260, 2009; Meignan et al., Leuk Lymphoma 51:2171-2180, 2010; Barrington et al., Eur J Nucl Med Mol Imaging 37:1824-1833, 2010). PET/CT status was compared with prospectively recorded patient outcomes. Central evaluation was performed on 119 scans. At diagnosis, 58 of 59 were recorded as positive, with a mean maximum standardized uptake value (SUV{sub max}) of 11.7 (range 4.6-35.6). There was no significant association between baseline SUV{sub max} and progression-free survival (PFS). Sixty post-induction scans were interpreted using both the IHP criteria and 5PS. Post-induction PET-positive status failed to predict progression when applying the IHP criteria [p = 0.14; hazard ratio (HR) 1.9; 95 % confidence interval (CI) 0.8-4.6] or 5PS with a cut-off ≥3 (p = 0.12; HR 2.0; 95 % CI 0.8-4.7). However, when applying the 5PS with a cut-off ≥4, there was a significantly inferior 42-month PFS in PET-positive patients of 25.0 % (95 % CI 3.7-55.8 %) versus 61.4 % (95 % CI 45.4-74.1 %) in PET-negative patients (p = 0.01; HR 3.1; 95 % CI 1.2-7.8). The positive predictive value (PPV) of post-induction PET with this liver cut-off was 75 %. The 42-month PFS for patients remaining PET-positive by local assessment was 31.1 % (95 % CI 10.2-55.0 %) vs 64.6 % (95 % CI 47.0-77.6 %) for PET

  3. Another breed of "service" animals: STARS study findings about pet ownership and recovery from serious mental illness.

    Science.gov (United States)

    Wisdom, Jennifer P; Saedi, Goal Auzeen; Green, Carla A

    2009-07-01

    This study elucidates the role of pets in recovery processes among adults with serious mental illness. Data derive from interviews with 177 HMO members with serious mental illness (52.2% women, average age 48.8 years) in the Study of Transitions and Recovery Strategies (STARS). Interviews and questionnaires addressed factors affecting recovery processes and included questions about pet ownership. Data were analyzed using a modified grounded theory method to identify the roles pets play in the recovery process. Primary themes indicate pets assist individuals in recovery from serious mental illness by (a) providing empathy and "therapy"; (b) providing connections that can assist in redeveloping social avenues; (c) serving as "family" in the absence of or in addition to human family members; and (d) supporting self-efficacy and strengthening a sense of empowerment. Pets appear to provide more benefits than merely companionship. Participants' reports of pet-related contributions to their well-being provide impetus to conduct more formal research on the mechanisms by which pets contribute to recovery and to develop pet-based interventions.

  4. Application of a semi-automatic ROI setting system for brain PET images to animal PET studies

    International Nuclear Information System (INIS)

    Kuge, Yuji; Akai, Nobuo; Tamura, Koji

    1998-01-01

    ProASSIST, a semi-automatic ROI (region of interest) setting system for human brain PET images, has been modified for use with the canine brain, and the performance of the obtained system was evaluated by comparing the operational simplicity for ROI setting and the consistency of ROI values obtained with those by a conventional manual procedure. Namely, we created segment maps for the canine brain by making reference to the coronal section atlas of the canine brain by Lim et al., and incorporated them into the ProASSIST system. For the performance test, CBF (cerebral blood flow) and CMRglc (cerebral metabolic rate in glucose) images in dogs with or without focal cerebral ischemia were used. In ProASSIST, brain contours were defined semiautomatically. In the ROI analysis of the test image, manual modification of the contour was necessary in half cases examined (8/16). However, the operation was rather simple so that the operation time per one brain section was significantly shorter than that in the manual operation. The ROI values determined by the system were comparable with those by the manual procedure, confirming the applicability of the system to these animal studies. The use of the system like the present one would also merit the more objective data acquisition for the quantitative ROI analysis, because no manual procedure except for some specifications of the anatomical features is required for ROI setting. (author)

  5. Cerebral Blood Flow Measurement Using fMRI and PET: A Cross-Validation Study

    Directory of Open Access Journals (Sweden)

    Jean J. Chen

    2008-01-01

    Full Text Available An important aspect of functional magnetic resonance imaging (fMRI is the study of brain hemodynamics, and MR arterial spin labeling (ASL perfusion imaging has gained wide acceptance as a robust and noninvasive technique. However, the cerebral blood flow (CBF measurements obtained with ASL fMRI have not been fully validated, particularly during global CBF modulations. We present a comparison of cerebral blood flow changes (ΔCBF measured using a flow-sensitive alternating inversion recovery (FAIR ASL perfusion method to those obtained using H2O15 PET, which is the current gold standard for in vivo imaging of CBF. To study regional and global CBF changes, a group of 10 healthy volunteers were imaged under identical experimental conditions during presentation of 5 levels of visual stimulation and one level of hypercapnia. The CBF changes were compared using 3 types of region-of-interest (ROI masks. FAIR measurements of CBF changes were found to be slightly lower than those measured with PET (average ΔCBF of 21.5±8.2% for FAIR versus 28.2±12.8% for PET at maximum stimulation intensity. Nonetheless, there was a strong correlation between measurements of the two modalities. Finally, a t-test comparison of the slopes of the linear fits of PET versus ASL ΔCBF for all 3 ROI types indicated no significant difference from unity (P>.05.

  6. Imaging benign pathology and variants with uptake in 68ga-Dotatate PET/CT studies

    International Nuclear Information System (INIS)

    Servente, L.; Bianco, C.; Gigirey, V.; Alonso, O.

    2017-01-01

    Purpose: To evaluate the physiological, anatomical variants and benign lesions in positron emission computed tomography (PET/CT) studies with 68Ga-DOTATATE.Materials and methods: We retrospectively reviewed PET/CT reports scanned with 68Ga-DOTATATE and selected those that contained words in the report related to anatomical, physiological variants and benign tumors. The degree of 68Ga-DOTATATE uptake was evaluated qualitatively and quantitatively by measuring the standarized uptake max value (SUVmax value). The anatomical location, SUVmax value and morphological CT image findings were recorded. All cases had clinical and imaging follow-up. Results: From a total of 772 PET/CT reports, 28 patients were obtained with 33 benign variants or tumors, 14 females and 14 males with a median age of 63 years. Uptake patterns were classified into four groups: anatomic and physiological variants (15), dependent on osteoblastic activity (4), dependent on inflammatory activity (10) and non-neuro-endocrine benign tumors (4).Discussion: Somatostatin receptors are overexpressed not only in the neuroendocrine system but also in other tissues. Physiological, anatomical variants and benign tumors expressing these receptors may be misleading. In the present work the frequency of this finding is 5.1%.Conclusion: Physiological variants and benign lesions (tumor and inflammatory) can accumulate 68Ga-DOTATATE since their tissues can express somatostatin receptors. The semiologic analysis of the tomographic component of this hybrid method enhances the diagnostic efficacy, optimizing PET/CT study performance. (authors) [es

  7. In vivo imaging of brain androgen receptors in rats: a [18F]FDHT PET study

    International Nuclear Information System (INIS)

    Khayum, M.A.; Doorduin, J.; Antunes, I.F.; Kwizera, C.; Zijlma, R.; Boer, J.A. den; Dierckx, R.A.J.O.; Vries, E.F.J. de

    2015-01-01

    Introduction: Steroid hormones like androgens play an important role in the development and maintenance of several brain functions. Androgens can act through androgen receptors (AR) in the brain. This study aims to demonstrate the feasibility of positron emission tomography (PET) with 16β-[ 18 F]fluoro-5α-dihydrotestosterone ([ 18 F]FDHT) to image AR expression in the brain. Methods: Male Wistar rats were either orchiectomized to inhibit endogenous androgen production or underwent sham-surgery. Fifteen days after surgery, rats were subjected to a 90-min dynamic [ 18 F]FDHT PET scan with arterial blood sampling. In a subset of orchiectomized rats, 1 mg/kg dihydrotestosterone was co-injected with the tracer in order to saturate the AR. Plasma samples were analyzed for the presence of radioactive metabolites by radio-TLC. Pharmacokinetic modeling was performed to quantify brain kinetics of the tracer. After the PET scan, the animals were terminated for ex-vivo biodistribution. Results: PET imaging and ex vivo biodistribution studies showed low [ 18 F]FDHT uptake in all brain regions, except pituitary. [ 18 F]FDHT uptake in the surrounding cranial bones was high and increased over time. [ 18 F]FDHT was rapidly metabolized in rats. Metabolism was significantly faster in orchiectomized rats than in sham-orchiectomized rats. Quantitative analysis of PET data indicated substantial spill-over of activity from cranial bones into peripheral brain regions, which prevented further analysis of peripheral brain regions. Logan graphical analysis and kinetic modeling using 1- and 2-tissue compartment models showed reversible and homogenously distributed tracer uptake in central brain regions. [ 18 F]FDHT uptake in the brain could not be blocked by endogenous androgens or administration of dihydrotestosterone. Conclusion: The results of this study indicate that imaging of AR availability in rat brain with [ 18 F]FDHT PET is not feasible. The low AR expression in the brain, the

  8. PET study of cholinergic system in the brain

    Energy Technology Data Exchange (ETDEWEB)

    Shinotoh, Hitoshi [Chiba Univ. (Japan). School of Medicine

    1999-01-01

    Recently, we have developed a method to measure acetylcholinesterase (AChE) activity, a functional marker for cholinergic system, by positron emission tomography (PET) and carbon-11 labeled N-methyl-4-piperidyl acetate. Kinetic analysis of the radioactivity in the brain and the plasma yielded a rate constant ``k 3`` as an index of AChE activity. The ratios for the k 3 values for the cerebral cortex/thalamus/cerebellum/striatum found in healthy participants were 1/ 3/ 8/ 10, respectively, corresponding well with AChE activity ratios in the brain at necropsy (1/ 3/ 8/ 38), except for the striatum. In 23 healthy volunteers (age range: 24-89 years), there was no age-related decline of k 3 values in the cerebral cortex, suggesting AChE activity is preserved in aged cerebral cortex. In 11 patients with Alzheimer`s disease, there was a significant reduction (-24%) of k 3 values in the cerebral cortex and hippocampus, suggesting a loss of ascending cholinergic system from the basal forebrain to the cerebral cortex and hippocampus. In 16 patients with Parkinson`s disease, there was a significant reduction (-18%) of k 3 values in the cerebral cortex. In 10 patients with progressive supra nuclear palsy, there was a significant reduction (-38%) of k 3 values in the thalamus. This technique is useful for investigating central cholinergic system in neuro degenerative disorders with dementia. (author)

  9. PET study of cholinergic system in the brain

    International Nuclear Information System (INIS)

    Shinotoh, Hitoshi

    1999-01-01

    Recently, we have developed a method to measure acetylcholinesterase (AChE) activity, a functional marker for cholinergic system, by positron emission tomography (PET) and carbon-11 labeled N-methyl-4-piperidyl acetate. Kinetic analysis of the radioactivity in the brain and the plasma yielded a rate constant ''k 3'' as an index of AChE activity. The ratios for the k 3 values for the cerebral cortex/thalamus/cerebellum/striatum found in healthy participants were 1/ 3/ 8/ 10, respectively, corresponding well with AChE activity ratios in the brain at necropsy (1/ 3/ 8/ 38), except for the striatum. In 23 healthy volunteers (age range: 24-89 years), there was no age-related decline of k 3 values in the cerebral cortex, suggesting AChE activity is preserved in aged cerebral cortex. In 11 patients with Alzheimer's disease, there was a significant reduction (-24%) of k 3 values in the cerebral cortex and hippocampus, suggesting a loss of ascending cholinergic system from the basal forebrain to the cerebral cortex and hippocampus. In 16 patients with Parkinson's disease, there was a significant reduction (-18%) of k 3 values in the cerebral cortex. In 10 patients with progressive supra nuclear palsy, there was a significant reduction (-38%) of k 3 values in the thalamus. This technique is useful for investigating central cholinergic system in neuro degenerative disorders with dementia. (author)

  10. Statistical study on the self-selection bias in FDG-PET cancer screening by a questionnaire survey

    International Nuclear Information System (INIS)

    Kita, Tamotsu; Yano, Fuzuki; Watanabe, Sadahiro; Soga, Shigeyoshi; Hama, Yukihiro; Shinmoto, Hiroshi; Kosuda, Shigeru

    2008-01-01

    A questionnaire survey was performed to investigate the possible presence of self-selection bias in 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) cancer screening (PET cancer screening). Responders to the questionnaires survey consisted of 80 healthy persons, who answered whether they undergo PET cancer screening, health consciousness, age, sex, and smoking history. The univariate and multivariate analyses on the four parameters were performed between the responders who were to undergo PET cancer screening and the responders who were not. Statistically significant difference was found in health consciousness between the above-mentioned two groups by both univariate and multivariate analysis with the odds ratio of 2.088. The study indicated that self-selection bias should exist in PET cancer screening. (author)

  11. A radiometabolite study of the serotonin transporter PET radioligand [11C]MADAM

    International Nuclear Information System (INIS)

    Gourand, F.; Emond, P.; Bergström, J.P.; Takano, A.; Gulyás, B.; Guilloteau, D.; Barré, L.; Halldin, C.

    2014-01-01

    Introduction: 11 C]MADAM is a radioligand suitable for PET studies of the serotonin transporter (SERT). Metabolite analysis in human and non-human plasma samples using HPLC separation has shown that [ 11 C]MADAM was rapidly metabolized. A possible metabolic pathway is the S-oxidation which could lead to SOMADAM and SO 2 MADAM. In vitro evaluation of these two potential metabolites has shown that SOMADAM exhibited a good affinity for SERT and a good selectivity for SERT over NET and DAT. Methods: Comparative PET imaging studies in non-human primate brain with [ 11 C]MADAM and [ 11 C]SOMADAM were carried out, and plasma samples were analyzed using reverse phase HPLC. We have explored the metabolism of [ 11 C]MADAM in rat brain with a view to understand its possible interference for brain imaging with PET. Results: PET imaging studies in non-human primate brain using [ 11 C]SOMADAM indicated that this tracer does not bind with high amounts to brain regions known to be rich in SERT. The fraction of [ 11 C]SOMADAM in non-human primate plasma was approximately 5% at 4 min and 1% at 15 min after [ 11 C]MADAM injection. HPLC analysis of brain sample after [ 11 C]MADAM injection to rats demonstrated that [ 11 C]SOMADAM was not detected in the brain. Conclusions: 11 C]SOMADAM is not superior over [ 11 C]MADAM as a SERT PET radioligand. Nevertheless, [ 11 C]SOMADAM has been identified as a minor labeled metabolite of [ 11 C]MADAM measured in monkey plasma. [ 11 C]SOMADAM was not detected in rat brain

  12. Brain connectivity study of brain tumor patients using MR-PET data: preliminary results

    International Nuclear Information System (INIS)

    Mendes, Ana Carina; Ribeiro, Andre Santos; Oros-Peusquens, Ana Maria; Langen, Karl Josef; Shah, Jon; Ferreira, Hugo Alexandre

    2015-01-01

    Brain activity results from anatomical and functional connections that can be disrupted or altered due to trauma or lesion. This work presents a first approach on the study of whole-brain connectivity of brain tumor patients using the Multimodal Imaging Brain Connectivity (MIBCA) toolbox. Two patients with glioblastoma lesions located in the left hemisphere (one in the motor cortex and the other in the temporal lobe) underwent simultaneous MRI and dynamic PET scans using a 3T MRI scanner with a BrainPET insert. The following data was acquired: T1-w MPRAGE (1x1x1mm 3 ), DTI (dir=30, b=0,800s/mm2, 2x2x2mm 3 ), and dynamic 18F-FET PET. The MIBCA toolbox was used to automatically pre-process MRI-PET data and to derive imaging and connectivity metrics from the multimodal data. Computed metrics included: cortical thickness from T1-w data; mean diffusivity (MD), fractional anisotropy (FA), node degree, clustering coefficient and pairwise ROI fibre tracking (structural connectivity) from DTI data; and standardized uptake value (SUV) from PET data. For all the metrics, the differences between left and right hemispherical structures were obtained, followed by a 25% threshold (except for SUV thresholded at 15%). Data was visualized in a connectogram, and both structural connectivity and metrics were studied in regions surrounding lesions. Preliminary results showed increased SUV values in regions surrounding the tumor for both patients. Patients also showed changes in structural connectivity involving these regions and also other more spatially distant regions such as the putamen and the pallidum, including decreased number of fibers between the subcortical structures themselves and with frontal regions. These findings suggest that the presence of a tumor may alter both local and more distant structural connections. Presently, a larger patient sample is being studied along with the inclusion of a control group to test the consistency of the findings.

  13. Automated analysis of small animal PET studies through deformable registration to an atlas

    International Nuclear Information System (INIS)

    Gutierrez, Daniel F.; Zaidi, Habib

    2012-01-01

    This work aims to develop a methodology for automated atlas-guided analysis of small animal positron emission tomography (PET) data through deformable registration to an anatomical mouse model. A non-rigid registration technique is used to put into correspondence relevant anatomical regions of rodent CT images from combined PET/CT studies to corresponding CT images of the Digimouse anatomical mouse model. The latter provides a pre-segmented atlas consisting of 21 anatomical regions suitable for automated quantitative analysis. Image registration is performed using a package based on the Insight Toolkit allowing the implementation of various image registration algorithms. The optimal parameters obtained for deformable registration were applied to simulated and experimental mouse PET/CT studies. The accuracy of the image registration procedure was assessed by segmenting mouse CT images into seven regions: brain, lungs, heart, kidneys, bladder, skeleton and the rest of the body. This was accomplished prior to image registration using a semi-automated algorithm. Each mouse segmentation was transformed using the parameters obtained during CT to CT image registration. The resulting segmentation was compared with the original Digimouse atlas to quantify image registration accuracy using established metrics such as the Dice coefficient and Hausdorff distance. PET images were then transformed using the same technique and automated quantitative analysis of tracer uptake performed. The Dice coefficient and Hausdorff distance show fair to excellent agreement and a mean registration mismatch distance of about 6 mm. The results demonstrate good quantification accuracy in most of the regions, especially the brain, but not in the bladder, as expected. Normalized mean activity estimates were preserved between the reference and automated quantification techniques with relative errors below 10 % in most of the organs considered. The proposed automated quantification technique is

  14. Brain connectivity study of brain tumor patients using MR-PET data: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Ana Carina [Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon (Portugal); Ribeiro, Andre Santos [Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon (Portugal); Centre for Neuropsychopharmacology, Division of Brain Sciences, Department of Medicine, Imperial College London, London (United Kingdom); Oros-Peusquens, Ana Maria; Langen, Karl Josef; Shah, Jon [Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich (Germany); Ferreira, Hugo Alexandre [Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon (Portugal)

    2015-05-18

    Brain activity results from anatomical and functional connections that can be disrupted or altered due to trauma or lesion. This work presents a first approach on the study of whole-brain connectivity of brain tumor patients using the Multimodal Imaging Brain Connectivity (MIBCA) toolbox. Two patients with glioblastoma lesions located in the left hemisphere (one in the motor cortex and the other in the temporal lobe) underwent simultaneous MRI and dynamic PET scans using a 3T MRI scanner with a BrainPET insert. The following data was acquired: T1-w MPRAGE (1x1x1mm{sup 3}), DTI (dir=30, b=0,800s/mm2, 2x2x2mm{sup 3}), and dynamic 18F-FET PET. The MIBCA toolbox was used to automatically pre-process MRI-PET data and to derive imaging and connectivity metrics from the multimodal data. Computed metrics included: cortical thickness from T1-w data; mean diffusivity (MD), fractional anisotropy (FA), node degree, clustering coefficient and pairwise ROI fibre tracking (structural connectivity) from DTI data; and standardized uptake value (SUV) from PET data. For all the metrics, the differences between left and right hemispherical structures were obtained, followed by a 25% threshold (except for SUV thresholded at 15%). Data was visualized in a connectogram, and both structural connectivity and metrics were studied in regions surrounding lesions. Preliminary results showed increased SUV values in regions surrounding the tumor for both patients. Patients also showed changes in structural connectivity involving these regions and also other more spatially distant regions such as the putamen and the pallidum, including decreased number of fibers between the subcortical structures themselves and with frontal regions. These findings suggest that the presence of a tumor may alter both local and more distant structural connections. Presently, a larger patient sample is being studied along with the inclusion of a control group to test the consistency of the findings.

  15. Value of surveillance {sup 18}F FDG PET/CT in colorectal cancer:comparison with conventional imaging studies

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Eun Kyoung; Yoo, Ie Ryung; Park, Hye Lim; Choi, Hyun Su; Han, Eun Ji; Kim, Sung Hoon; Chung, Soo Kyo; O, Joo Hyun [The Catholic Univ. of Korea, Seoul (Korea, Republic of)

    2012-09-15

    To assess the value of PET/CT for detecting local or distant recurrence in patients who undergo surgery for colorectal cancer (CRC)and to compare the accuracy of PET/CT to that of conventional imaging studies (CIS). Tumor surveillance PET/CT scans done between March 2005 and December 2009 of disease free patients after surgery with or without adjuvant chemotherapy for CRC were retrospectively studied. CIS (serial enhanced CT from lung base to pelvis and plain chest radiograph)were performed within 1 month of PET/CT. We excluded patients with distant metastasis on initial staging, a known recurrent tumor, and a lack of follow up imaging. The final diagnosis was based on at least 6 months of follow up with colonoscopy, biopsy, and serial imaging studies in combination with carcinoembryonic antigen levels. A total of 262 PET/CT scans of 245 patients were included. Local and distant recurrences were detected in 27 cases (10.3%). On case based analysis, the overall sensitivity, specificity, and accuracy were 100, 97.0, and 97.3% for PET/CT and 85.1, 97.0, and 95.8% for CIS, respectively. On lesion based analysis, PET/CT detected more lesions compared to CIS in local recurrence and lung metastasis. PET/CT and CIS detected the same number of lesions in abdominal lymph nodes, hepatic metastasis, and peritoneal carcinomatosis. PET/CT detected two more metachronous tumors than did CIS in the lung and thyroid gland. PET/CT detected more recurrences in patients who underwent surgery for CRC than did CIS and had the additional advantage of evaluating the entire body during a single scan.

  16. HPLC study of migration of terephthalic acid and isophthalic acid from PET bottles into edible oils.

    Science.gov (United States)

    Khaneghah, Amin Mousavi; Limbo, Sara; Shoeibi, Shahram; Mazinani, Somayeh

    2014-08-01

    Polyethylene terephthalate (PET) containers for food oil packaging were evaluated with a newly established determination method for terephthalic acid (TPA) and isophthalic acid (IPA). The analysis of monomers, TPA and IPA that migrate from PET bottles into oils was performed using high-pressure liquid chromatography with a diode array detector. Three types of commercial oils (sunflower oil, canola oil and blended oil which included sunflower oil, soy bean oil and cottonseed oil) were bottled in PET containers. These samples were incubated for 10 days at 49 °C as accelerated test condition. The means of recovery for this method varied from 70% to 72% and from 101% to 111% for TPA and IPA, respectively. The results showed that the amounts of specific migration of TPA and IPA into the samples conform to European Union legislation that identifies specific migration limits. More important, the results highlighted a different behavior of migration as a function of the fatty acid profile. Previous investigations have been performed with food simulants such as HB307 or 20% ethanol but our study used real food samples and determined trace amounts of the migrated compounds. Further investigation will be needed to better explain the influence of fatty acid conformation on migration of PET monomers. © 2013 Society of Chemical Industry.

  17. Evaluation of PET and laparoscopy in STagIng advanced gastric cancer: a multicenter prospective study (PLASTIC-study).

    Science.gov (United States)

    Brenkman, H J F; Gertsen, E C; Vegt, E; van Hillegersberg, R; van Berge Henegouwen, M I; Gisbertz, S S; Luyer, M D P; Nieuwenhuijzen, G A P; van Lanschot, J J B; Lagarde, S M; de Steur, W O; Hartgrink, H H; Stoot, J H M B; Hulsewe, K W E; Spillenaar Bilgen, E J; van Det, M J; Kouwenhoven, E A; van der Peet, D L; Daams, F; van Sandick, J W; van Grieken, N C T; Heisterkamp, J; van Etten, B; Haveman, J W; Pierie, J P; Jonker, F; Thijssen, A Y; Belt, E J T; van Duijvendijk, P; Wassenaar, E; van Laarhoven, H W M; Wessels, F J; Haj Mohammad, N; van Stel, H F; Frederix, G W J; Siersema, P D; Ruurda, J P

    2018-04-20

    Initial staging of gastric cancer consists of computed tomography (CT) and gastroscopy. In locally advanced (cT3-4) gastric cancer, fluorodeoxyglucose positron emission tomography with CT (FDG-PET/CT or PET) and staging laparoscopy (SL) may have a role in staging, but evidence is scarce. The aim of this study is to evaluate the impact and cost-effectiveness of PET and SL in addition to initial staging in patients with locally advanced gastric cancer. This prospective observational cohort study will include all patients with a surgically resectable, advanced gastric adenocarcinoma (cT3-4b, N0-3, M0), that are scheduled for treatment with curative intent after initial staging with gastroscopy and CT. The modalities to be investigated in this study is the addition of PET and SL. The primary outcome of this study is the proportion of patients in whom the PET or SL lead to a change in treatment strategy. Secondary outcome parameters are: diagnostic performance, morbidity and mortality, quality of life, and cost-effectiveness of these additional diagnostic modalities. The study recently started in August 2017 with a duration of 36 months. At least 239 patients need to be included in this study to demonstrate that the diagnostic modalities are break-even. Based on the annual number of gastrectomies in the participating centers, it is estimated that approximately 543 patients are included in this study. In this study, it is hypothesized that performing PET and SL for locally advanced gastric adenocarcinomas results in a change of treatment strategy in 27% of patients and an annual cost-reduction in the Netherlands of €916.438 in this patient group by reducing futile treatment. The results of this study may be applicable to all countries with comparable treatment algorithms and health care systems. NCT03208621 . This trial was registered prospectively on June 30, 2017.

  18. Evaluation of PET Scanner Performance in PET/MR and PET/CT Systems: NEMA Tests.

    Science.gov (United States)

    Demir, Mustafa; Toklu, Türkay; Abuqbeitah, Mohammad; Çetin, Hüseyin; Sezgin, H Sezer; Yeyin, Nami; Sönmezoğlu, Kerim

    2018-02-01

    The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor. According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated aspects were spatial resolution, sensitivity, scatter fraction, count rate performance, image quality, count loss and random events correction accuracy. The findings of this study demonstrated superior sensitivity (~ 4 folds) of PET scanner in PET/MR compared to PET/CT system. Image quality test exhibited higher contrast in PET/MR (~ 9%) compared with PET/CT. The scatter fraction of PET/MR was 43.4% at noise equivalent count rate (NECR) peak of 218 kcps and the corresponding activity concentration was 17.7 kBq/cc. Whereas the scatter fraction of PET/CT was found as 39.2% at NECR peak of 72 kcps and activity concentration of 24.3 kBq/cc. The percentage error of the random event correction accuracy was 3.4% and 3.1% in PET/MR and PET/CT, respectively. It was concluded that PET/MR system is about 4 times more sensitive than PET/CT, and the contrast of hot lesions in PET/MR was ~ 9% higher than PET/CT. These outcomes also emphasize the possibility to achieve excellent clinical PET images with low administered dose and/or a short acquisition time in PET/MR.

  19. PET-Studies in parkinson's disease; Untersuchungen mit der Positronen-Emissions-Tomographie (PET) bei Patienten mit Morbus Parkinson

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, J. [Klinik fuer Neurologie, Univ. Leipzig (Germany)

    2002-09-01

    Positron-emission-tomography (PET) has enabled to study the metabolism and blood flow in specific brain areas. Besides, there is a variety of radiotracers that allow quantification of the function of distinct molecules. In respect to Parkinson's disease, PET allowed for the first time to assess the number of dopaminergic neurons in vivo. Thus, helping confirming a dopaminergic deficit, measuring disease progression and also help to determine the function of dopaminergic grafts. Current research has shifted to determine the role of related neurotransmitter systems in the pathophysiology of Parkinson's disease. (orig.) [German] Die positronen-emissions-tomographie (PET) bietet neben der Messung von Metabolismus und Blutfluss die Moeglichkeit der Darstellung von einzelnen Molekuelen. Bei Patienten mit Morbus Parkinson hat es diese Technik erstmals erlaubt, die Anzahl der dopaminergen Neurone zu quantifizieren, wodurch die Diagnose gesichert, die Progression der Erkrankung beurteilt und auch das Anwachsen von Implantaten beurteilt werden kann. Die PET hat einen wesentlichen Beitrag zu unserem heutigen Wissen ueber die Pathophysiologie dieser Erkrankung beigetragen. (orig.)

  20. Neurological manifestations and PET studies of the thalamic vascular lesions

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Shinji; Kawamura, Mitsuru; Hirayama, Keizo [Chiba Univ. (Japan). School of Medicine

    1995-02-01

    We divided 38 patients with cerebrovascular disease of the thalamus into 5 groups according to the site of the thalamic lesions as confirmed by X-ray CT and/or MRI. In 16 patients, we examined the cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO{sub 2}) by positron emission tomography (PET). In the anteromedial thalamic lesion group, patients displayed disturbances of spontaneity, memory, reading and writing. CBF and CMRO{sub 2} were decreased in the frontal, parietal and temporal lobes on the side of the lesion. In the dorsolateral thalamic lesion group, ataxic hemiparesis was a characteristic symptom. CBF and CMRO{sub 2} were decreased in frontoparietal lobes on the side of the lesion. In the group with lesions confined to the nucleus ventralis posterioris thalami, the main symptoms were sensory disturbance, with cheiro-oral sensory syndrome being particularly evident. CBF and CMRO{sub 2} were decreased in the parietal lobe on the side of the lesion. In the group with posterolateral thalamic lesions without pulvinar involvement, patients exhibited thalamic syndrome without thalamic pain. CBF and CMRO{sub 2} were decreased in the frontoparietal and temporal lobes on the side of the lesion. In contrast, in the group with posterolateral thalamic lesions with pulvinar involvement, all patients showed thalamic pain. The decrease in CBF and CMRO{sub 2} extended to the inferomedial region of the temporal lobe in addition to the area of decreased CBF and CMRO{sub 2} observed in the group with posterolateral thalamic lesions without pulvinar involvement. Based on these results, we speculate that the neurological manifestations of thalamic vascular disease are associated with a decrease in cortical CBF and CMRO{sub 2} secondary to the thalamic lesions. (author).

  1. Neurological manifestations and PET studies of the thalamic vascular lesions

    International Nuclear Information System (INIS)

    Matsuda, Shinji; Kawamura, Mitsuru; Hirayama, Keizo

    1995-01-01

    We divided 38 patients with cerebrovascular disease of the thalamus into 5 groups according to the site of the thalamic lesions as confirmed by X-ray CT and/or MRI. In 16 patients, we examined the cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO 2 ) by positron emission tomography (PET). In the anteromedial thalamic lesion group, patients displayed disturbances of spontaneity, memory, reading and writing. CBF and CMRO 2 were decreased in the frontal, parietal and temporal lobes on the side of the lesion. In the dorsolateral thalamic lesion group, ataxic hemiparesis was a characteristic symptom. CBF and CMRO 2 were decreased in frontoparietal lobes on the side of the lesion. In the group with lesions confined to the nucleus ventralis posterioris thalami, the main symptoms were sensory disturbance, with cheiro-oral sensory syndrome being particularly evident. CBF and CMRO 2 were decreased in the parietal lobe on the side of the lesion. In the group with posterolateral thalamic lesions without pulvinar involvement, patients exhibited thalamic syndrome without thalamic pain. CBF and CMRO 2 were decreased in the frontoparietal and temporal lobes on the side of the lesion. In contrast, in the group with posterolateral thalamic lesions with pulvinar involvement, all patients showed thalamic pain. The decrease in CBF and CMRO 2 extended to the inferomedial region of the temporal lobe in addition to the area of decreased CBF and CMRO 2 observed in the group with posterolateral thalamic lesions without pulvinar involvement. Based on these results, we speculate that the neurological manifestations of thalamic vascular disease are associated with a decrease in cortical CBF and CMRO 2 secondary to the thalamic lesions. (author)

  2. Direct parametric reconstruction in dynamic PET myocardial perfusion imaging: in vivo studies

    Science.gov (United States)

    Petibon, Yoann; Rakvongthai, Yothin; El Fakhri, Georges; Ouyang, Jinsong

    2017-05-01

    Dynamic PET myocardial perfusion imaging (MPI) used in conjunction with tracer kinetic modeling enables the quantification of absolute myocardial blood flow (MBF). However, MBF maps computed using the traditional indirect method (i.e. post-reconstruction voxel-wise fitting of kinetic model to PET time-activity-curves-TACs) suffer from poor signal-to-noise ratio (SNR). Direct reconstruction of kinetic parameters from raw PET projection data has been shown to offer parametric images with higher SNR compared to the indirect method. The aim of this study was to extend and evaluate the performance of a direct parametric reconstruction method using in vivo dynamic PET MPI data for the purpose of quantifying MBF. Dynamic PET MPI studies were performed on two healthy pigs using a Siemens Biograph mMR scanner. List-mode PET data for each animal were acquired following a bolus injection of ~7-8 mCi of 18F-flurpiridaz, a myocardial perfusion agent. Fully-3D dynamic PET sinograms were obtained by sorting the coincidence events into 16 temporal frames covering ~5 min after radiotracer administration. Additionally, eight independent noise realizations of both scans—each containing 1/8th of the total number of events—were generated from the original list-mode data. Dynamic sinograms were then used to compute parametric maps using the conventional indirect method and the proposed direct method. For both methods, a one-tissue compartment model accounting for spillover from the left and right ventricle blood-pools was used to describe the kinetics of 18F-flurpiridaz. An image-derived arterial input function obtained from a TAC taken in the left ventricle cavity was used for tracer kinetic analysis. For the indirect method, frame-by-frame images were estimated using two fully-3D reconstruction techniques: the standard ordered subset expectation maximization (OSEM) reconstruction algorithm on one side, and the one-step late maximum a posteriori (OSL-MAP) algorithm on the other

  3. Direct parametric reconstruction in dynamic PET myocardial perfusion imaging: in-vivo studies

    Science.gov (United States)

    Petibon, Yoann; Rakvongthai, Yothin; Fakhri, Georges El; Ouyang, Jinsong

    2017-01-01

    Dynamic PET myocardial perfusion imaging (MPI) used in conjunction with tracer kinetic modeling enables the quantification of absolute myocardial blood flow (MBF). However, MBF maps computed using the traditional indirect method (i.e. post-reconstruction voxel-wise fitting of kinetic model to PET time-activity-curves -TACs) suffer from poor signal-to-noise ratio (SNR). Direct reconstruction of kinetic parameters from raw PET projection data has been shown to offer parametric images with higher SNR compared to the indirect method. The aim of this study was to extend and evaluate the performance of a direct parametric reconstruction method using in-vivo dynamic PET MPI data for the purpose of quantifying MBF. Dynamic PET MPI studies were performed on two healthy pigs using a Siemens Biograph mMR scanner. List-mode PET data for each animal were acquired following a bolus injection of ~7-8 mCi of 18F-flurpiridaz, a myocardial perfusion agent. Fully-3D dynamic PET sinograms were obtained by sorting the coincidence events into 16 temporal frames covering ~5 min after radiotracer administration. Additionally, eight independent noise realizations of both scans - each containing 1/8th of the total number of events - were generated from the original list-mode data. Dynamic sinograms were then used to compute parametric maps using the conventional indirect method and the proposed direct method. For both methods, a one-tissue compartment model accounting for spillover from the left and right ventricle blood-pools was used to describe the kinetics of 18F-flurpiridaz. An image-derived arterial input function obtained from a TAC taken in the left ventricle cavity was used for tracer kinetic analysis. For the indirect method, frame-by-frame images were estimated using two fully-3D reconstruction techniques: the standard Ordered Subset Expectation Maximization (OSEM) reconstruction algorithm on one side, and the One-Step Late Maximum a Posteriori (OSL-MAP) algorithm on the other

  4. The preliminary study of 18F-FDG PET in diagnosis of Alzheimer's disease

    International Nuclear Information System (INIS)

    Ma, Y.; Zhang, X.; Le, D.

    2000-01-01

    To investigate the imaging characteristic and diagnostic criteria of 18F-FDG brain PET in detecting Alzheimer's disease (AD). The study included in 12 normal subject, 12 patients with AD, 6 patients with vascular dementia, 3 patients with Lewy body disease (LBD) and 2 patients with mixed dementia. The dementia severity was measured by ESD and MMSE. 12 cases had mild, 7 moderate and 4 severe dementia. 23 patients and 6 normal subjects underwent MR imaging of the brain. All participants fasted for at least 6 hours. 40 minutes after intravenous administration of 185-370 MBq 18F-FDG, 2D brain scan in 25 cases and 3D scan in 10 cases were performed using SIEMENS ECAT 47 scanner. The transaxial, coronal and sagittal images were then reconstructed by computer. At the same time, semiquantitative analysis was also applied to help evaluation using the ratio of mean radioactivity between cerebral lobe to cerebellum (Rcl/cb). In normal subjects PET scan showed clear images of cerebral cortex, basal ganglia, thalamus and cerebellum with symmetrical distribution of radioactivity. 22 of 23 patients were found to have decreased uptake of FDG in the brain. 20 patients had cerebral atrophy and it also appeared in 6 normal elder people. PET images for Alzheimer's disease were classified in 6 normal elder people. PET image for Alzheimer's 3 patterns: bilateral parietal hypo metabolism in 5 cases, bilateral temporo-parietal hypo metabolism in 4 cases and unilateral temporo-parietal hypo metabolism in 3 cases. The Rcl/cb of AD patents in parietal and temporal was significantly decreased than normal subjects (p<0.05). PET images for non-AD dementia were also classified 3 patterns: multiple and asymmetrical patch foci with decreased radioactivity in 8 cases, bilateral temporo-parietal with diffuse cortical hypo metabolism in 2 cases, and normal imaging in 1 case. The hypo metabolic involvement was accorded with severity of dementia. The more dementia had, the bigger hypometabloic region

  5. Problem solving ability and repetition of deliberate self-harm: a multicentre study.

    NARCIS (Netherlands)

    McAuliffe, C.; Corcoran, P.; Keeley, H.S.; Arensman, E.; Bille Brahe, U.; de Leio, D.; Fekete, S.; Hawton, K.; Hjelmeland, H.; Kelleher, M.; Kerkhof, A.J.F.M.; Lonnqvist, J.; Michel, K.; Salander Renberg, E.; Schmidtke, A.; van Heeringen, K.; Wasserman, D.

    2006-01-01

    Background. While recent studies have found problem-solving impairments in individuals who engage in deliberate self-harm (DSH), few studies have examined repeaters and non-repeaters separately. The aim of the present study was to investigate whether specific types of problem-solving are associated

  6. Improving PET Quantification of Small Animal [68Ga]DOTA-Labeled PET/CT Studies by Using a CT-Based Positron Range Correction.

    Science.gov (United States)

    Cal-Gonzalez, Jacobo; Vaquero, Juan José; Herraiz, Joaquín L; Pérez-Liva, Mailyn; Soto-Montenegro, María Luisa; Peña-Zalbidea, Santiago; Desco, Manuel; Udías, José Manuel

    2018-01-19

    Image quality of positron emission tomography (PET) tracers that emits high-energy positrons, such as Ga-68, Rb-82, or I-124, is significantly affected by positron range (PR) effects. PR effects are especially important in small animal PET studies, since they can limit spatial resolution and quantitative accuracy of the images. Since generators accessibility has made Ga-68 tracers wide available, the aim of this study is to show how the quantitative results of [ 68 Ga]DOTA-labeled PET/X-ray computed tomography (CT) imaging of neuroendocrine tumors in mice can be improved using positron range correction (PRC). Eighteen scans in 12 mice were evaluated, with three different models of tumors: PC12, AR42J, and meningiomas. In addition, three different [ 68 Ga]DOTA-labeled radiotracers were used to evaluate the PRC with different tracer distributions: [ 68 Ga]DOTANOC, [ 68 Ga]DOTATOC, and [ 68 Ga]DOTATATE. Two PRC methods were evaluated: a tissue-dependent (TD-PRC) and a tissue-dependent spatially-variant correction (TDSV-PRC). Taking a region in the liver as reference, the tissue-to-liver ratio values for tumor tissue (TLR tumor ), lung (TLR lung ), and necrotic areas within the tumors (TLR necrotic ) and their respective relative variations (ΔTLR) were evaluated. All TLR values in the PRC images were significantly different (p DOTA-labeled PET/CT imaging of mice with neuroendocrine tumors, hence demonstrating that these techniques could also ameliorate the deleterious effect of the positron range in clinical PET imaging.

  7. ''Ecstasy''-induced changes of cerebral glucose metabolism and their correlation to acute psychopathology. A 18-FDG PET study

    International Nuclear Information System (INIS)

    Schreckenberger, M.; Sabri, O.; Arning, C.; Zimny, M.; Zeggel, T.; Wagenknecht, G.; Kaiser, H.J.; Buell, U.; Gouzoulis-Mayfrank, E.; Sass, H.

    1999-01-01

    The aim of this study was to determine the acute effects of the 'Ecstasy' analogue MDE (3,4-methylene dioxyethamphetamine) on cerebral glucose metabolism (rMRGlu) of healthy volunteers and to correlate neurometabolism with acute psychopathology. In a radomized double-blind trial, 15 healthy volunteers without a history of drug abuse were examined with fluorine-18-deoxyglucose ( 18 FDG) positron emission tomography (PET) 110-120 min after oral administration of 2 mg/kg MDE (n=7) or placebo (n=8). Two minutes prior to radiotracer injection, constant cognitive stimulation was started and maintained for 32 min using a word repetition paradigm to ensure constant and comparable mental conditions during cerebral glucose uptake. Individual brain anatomy was represented using T1-weighted 3D flash magnetic resonance imaging (MRI), followed by manual regionalization into 108 regions of interest and PET/MRI overlay. After absolute quantification of rMR-Glu and normalization to global metabolism, normalized rMRGlu under MDE was compared to placebo using the Mann-Whitney U-test. Acute psychopathology was assessed using the Positive and Negative Syndrome Scale (PANSS) and rMRGlu was correlated to PANSS scores according to Spearman. MDE subjects showed significantly decreased rMRGlu in the bilateral frontal cortex: left frontal posterior (-7.1%, P<0.05) and right prefrontal superior (-4.6%, P<0.05). On the other hand, rMR-Glu was significantly increased in the bilateral cerebellum (right: +10.1%, P<0.05; left: +7.6%, P<0.05) and in the right putamen (+6.2%, P<0.05). There were positive correlations between rMRGlu in the middle right cingulate and grandiosity (r=0.87; P<0.05), both the right amygadala (r=0.90, P<0.01) and the left posterior cingulate (r=0.90, P<0.01) to difficulties in abstract thinking, and the right frontal inferior (r=0.85, P<0.05), right anterior cingulate (r=0.93, P<0.01), and left anterior cingulate (r=0.85, P<0.05) to attentional deficits. A negative

  8. Low-Frequency Repetitive Transcranial Magnetic Stimulation and Intensive Occupational Therapy for Poststroke Patients with Upper Limb Hemiparesis: Preliminary Study of a 15-Day Protocol

    Science.gov (United States)

    Kakuda, Wataru; Abo, Masahiro; Kobayashi, Kazushige; Momosaki, Ryo; Yokoi, Aki; Fukuda, Akiko; Ishikawa, Atsushi; Ito, Hiroshi; Tominaga, Ayumi

    2010-01-01

    The purpose of the study was to determine the safety and feasibility of a 15-day protocol of low-frequency repetitive transcranial magnetic stimulation (rTMS) combined with intensive occupational therapy (OT) on motor function and spasticity in hemiparetic upper limbs in poststroke patients. Fifteen poststroke patients (age at study entry 55 [plus…

  9. Simultaneous whole-body 18F-FDG PET-MRI in primary staging of breast cancer: A pilot study

    International Nuclear Information System (INIS)

    Taneja, Sangeeta; Jena, Amarnath; Goel, Reema; Sarin, Ramesh; Kaul, Sumaid

    2014-01-01

    Highlights: • Initial staging of breast cancer important in treatment planning and prognostication. • We assessed role of simultaneous 18 F-FDG PET-MRI in initial staging of breast cancer. • Primary, nodes and metastases on PET, MRI and PET-MRI for count and diagnostic confidence. • High diagnostic accuracy and confidence in detecting index and satellite lesions. • Comprehensive nodal and distant metastases staging with altered management (12 cases). - Abstract: Purpose: Accurate initial staging in breast carcinoma is important for treatment planning and for establishing the likely prognosis. The purpose of this study was to assess the utility of whole body simultaneous 18 F-FDG PET-MRI in initial staging of breast carcinoma. Methods: 36 patients with histologically confirmed invasive ductal carcinoma underwent simultaneous whole body 18 F-FDG PET-MRI on integrated 3 T PET-MR scanner (Siemens Biograph mMR) for primary staging. Primary lesion, nodes and metastases were evaluated on PET, MRI and PET-MRI for lesion count and diagnostic confidence (DC). Kappa co relation analysis was done to assess agreement between the satellite, nodal and metastatic lesions detected by PET and MRI. Histopathology, clinical/imaging follow-up served as the reference standard. Results: 36 patients with 37 histopathologically proven index breast cancer were retrospectively studied. Of 36 patients, 25 patients underwent surgery and 11 patients received systemic therapy. All index cancers were seen on PET and MR. Fused PET-MRI showed highest diagnostic confidence score of 5 as compared to PET (median 4; range 3–5) and MRI (median 4; range 4–5) alone. 2/36 (5.5%) patients were detected to have unsuspected contralateral synchronous cancer. 47 satellite lesions were detected on DCE MRI of which 23 were FDG avid with multifocality and multicentricity in 21 (58%) patients. Kappa co relation analysis revealed fair agreement for satellite lesion detection by the two modalities (κ

  10. A comparison study of PET, NMR, and CT imaging in cerebral ischemia

    International Nuclear Information System (INIS)

    Babikian, V.L.; Ford, C.S.; Buonanno, F.S.; Kistler, J.P.; Ackerman, R.H.; Alpert, N.M.; Correia, J.A.; Johnson, K.A.; Buxton, R.B.

    1987-01-01

    Whether ischemia without infarction produces recognizable changes in relaxation times of ischemic but viable brain is an important, unresolved issue. Therefore, a study was initiated of patients with cerebral ischemia, using positron emission tomography (PET), NMR, and computed tomography (CT) to compare and contrast the pathophysiologic information provided by each and to study the issue of whether cerebral ischemia without infarction can be appreciated by proton NMR imaging. Here the initial results are reported. 4 refs.; 2 figs.; 1 table

  11. Reduction of freezing of gait in Parkinson's disease by repetitive robot-assisted treadmill training: a pilot study

    Directory of Open Access Journals (Sweden)

    Friedman Joseph H

    2010-10-01

    Full Text Available Abstract Background Parkinson's disease is a chronic, neurodegenerative disease characterized by gait abnormalities. Freezing of gait (FOG, an episodic inability to generate effective stepping, is reported as one of the most disabling and distressing parkinsonian symptoms. While there are no specific therapies to treat FOG, some external physical cues may alleviate these types of motor disruptions. The purpose of this study was to examine the potential effect of continuous physical cueing using robot-assisted sensorimotor gait training on reducing FOG episodes and improving gait. Methods Four individuals with Parkinson's disease and FOG symptoms received ten 30-minute sessions of robot-assisted gait training (Lokomat to facilitate repetitive, rhythmic, and alternating bilateral lower extremity movements. Outcomes included the FOG-Questionnaire, a clinician-rated video FOG score, spatiotemporal measures of gait, and the Parkinson's Disease Questionnaire-39 quality of life measure. Results All participants showed a reduction in FOG both by self-report and clinician-rated scoring upon completion of training. Improvements were also observed in gait velocity, stride length, rhythmicity, and coordination. Conclusions This pilot study suggests that robot-assisted gait training may be a feasible and effective method of reducing FOG and improving gait. Videotaped scoring of FOG has the potential advantage of providing additional data to complement FOG self-report.

  12. Effect of electroconvulsive therapy in repetitive transcranial magnetic stimulation non-responder MDD patients: a preliminary study.

    Science.gov (United States)

    Dannon, P N; Grunhaus, L

    2001-09-01

    The aim of this study was to measure the effectiveness of ECT in-patients who had failed to respond to a course of repetitive transcranial magnetic stimulation (rTMS) treatment. Seventeen patients with severe MDD who had not responded to a course of rTMS were switched to receive ECT treatments. All the patients were assessed with the Hamilton Rating Scale for Depression, the Global Assessment Functioning Scale, the Global Depression Scale, and the Pittsburgh Sleep Quality Index. Response to the treatment was defined as a 50% decrease in HDRS final score and a final GAS higher than 60. Seven out of 17 patients responded to ECT. Three out of 5 non-psychotics and 4 out of 12 psychotic patients responded. ECT seems to be an effective treatment for 40% of patients who failed to respond to rTMS treatment. Whether this is a result of reduced responsiveness to ECT in rTMS-resistant patients or a consequence of small sample size requires further study.

  13. Long-term repetitive sodium lauryl sulfate-induced irritation of the skin: an in vivo study.

    Science.gov (United States)

    Branco, Nara; Lee, Ivy; Zhai, Hongbo; Maibach, Howard I

    2005-11-01

    Skin may adapt to topical irritants through accommodation. This study focuses on long-term exposure to irritants and attempts to demonstrate accommodation. Sodium lauryl sulfate (SLS) induced irritant contact dermatitis at 3 concentrations (0.025% to 0.075%). Distilled water, acetone and an empty chamber served as controls. Experimental compounds were applied to forearms of 7 healthy volunteers for 24 hr before replacing by a fresh chamber for 6 non-consecutive weeks over 103 days. Possible accommodation was quantified by visual scoring (erythema and dryness) and by bioengineering parameters: transepidermal water loss (TEWL), capacitance, chromametry and laser Doppler flowmetry (LDF). Significant erythema, dryness, elevated TEWL, skin colour reflectance and LDF values occurred during the exposure periods. Upon repeat exposure, an immediate and augmented response in erythema, TEWL, skin colour reflectance and LDF developed. However, irritant skin changes were not sustained. Irritation parameters return to baseline after cessation of exposure. There was no evidence of sustained irritation or accommodation after the last exposure. Study findings do not document sustained accommodation or adaptive hyposensitivity after long-term repetitive irritant exposure under these test conditions. Alternative models should be developed to prove or disprove the accommodation hypothesis.

  14. A Comparison between the Occurrence of Pauses, Repetitions and Recasts under Conditions of Face-to-Face and Computer-Mediated Communication: A Preliminary Study

    Science.gov (United States)

    Cabaroglu, Nese; Basaran, Suleyman; Roberts, Jon

    2010-01-01

    This study compares pauses, repetitions and recasts in matched task interactions under face-to-face and computer-mediated conditions. Six first-year English undergraduates at a Turkish University took part in Skype-based voice chat with a native speaker and face-to-face with their instructor. Preliminary quantitative analysis of transcripts showed…

  15. [Obsessive-compulsive symptoms, tics, stereotypic movements or need for absolute consistency? The occurrence of repetitive activities in patients with pervasive developmental disorders--case studies].

    Science.gov (United States)

    Bryńska, Anita; Lipińska, Elzbieta; Matelska, Monika

    2011-01-01

    Repetitive and stereotyped behaviours in the form of stereotyped interests or specific routine activities are one ofthe diagnostic criteria in pervasive developmental disorders. The occurrence of repetitive behaviours in patients with pervasive developmental disorders is a starting point for questions about the type and classification criteria of such behaviours. The aim of the article is to present case studies of patients with pervasive developmental disorders and co-morbid symptoms in the form of routine activities, tics, obsessive-compulsive symptoms or stereotyped behaviours. The first case study describes a patient with Asperger's syndrome and obsessive compulsive symptoms. The diagnostic problems regarding complex motor tics are discussed in the second case study which describes a patient with Asperger's syndrome and Gilles de la Tourette syndrome. The third and fourth case study describes mono-zygotic twins with so called High Functioning Autism whose repetitive activities point to either obsessive compulsive symptoms, stereotypic movements, need for absolute consistency or echopraxia. The possible comorbidity of pervasive developmental disorders and symptoms in the form of repetitive behaviours, possible interactions as well as diagnostic challenges is discussed in the article.

  16. A study on development of fast silicon photomultipliers for TOF-PET Application

    International Nuclear Information System (INIS)

    Lee, Chae Hun

    2011-02-01

    The PET technique is based on the fact that the radioisotopes introduced to the body as labels tracer molecules emitting positrons. To improve the image quality of PET, the Time-Of-Flight (TOF) technique was proposed, so it reduces the statistical noise by confining the Line-Of-Response using the information measuring the time difference between two opposite PET detectors. Nowadays, the components of PET detectors such as scintillation crystals, photo-sensors, and their readout electronics were well developed. Despite major improvement in imaging detector technologies, solid- state photo-sensors have not been replaced instead of the vacuum type PM tubes whose performance is still superior to others, even though they have some disadvantages such as mal-function in magnetic field, high operating bias, bulkiness, and high cost. One of the candidates for the photo-sensor in TOF-PET detectors to replace the PMTs is 'Silicon Photomultiplier (SiPM)' which has high gain comparable to PMTs, high photon detection efficiency, non-sensitive to MR, low operating bias about 30 V, and low cost. To apply the SiPM in TOF-PET, the timing characteristics should be improved more. In this study, SiPM was studied to improve the timing performance. In PET detectors, the timing resolution is directly related to the amplitude to the rise time ratio. As the ratio increases, the timing performance can be enhanced. PDE of SiPM was modeled to increase the amplitude of PET detectors based on SiPM with dynamic range consideration. The optimum micro-pixel size, consequently the number of micro-pixels for TOF-PET detectors were calculated from PDE modeling. To shorten the rise time of PET detector, the single photon pulse shape of SiPM is needed to modify. To do this, a quenching capacitor in a micro-pixel of SiPM was integrated. Circuit modeling was done in order to know how it affects the pulse shape. SiPM was fabricated at National NanoFab Center with the modeling results. A SiPM pixel has 1912

  17. Studies of high repetition rate laser-produced plasma soft-X-ray amplifiers

    International Nuclear Information System (INIS)

    Cassou, K.

    2006-12-01

    The progress made as well on the Ti:Sa laser system, as in the control and the knowledge of laser produced X-UV sources allowed the construction of a X-UV laser station dedicated to the applications. My thesis work falls under the development of this station and more particularly on the characterization of a X-UV laser plasma amplifier. The experimental study relates to the coupling improvement of the pump infra-red laser with plasma within the framework of the transient collisional X-UV laser generation. These X-UV lasers are generated in a plasma formed by the interaction of a solid target and a laser pulse of approximately 500 ps duration, followed by a second infra-red laser pulse known as of pump (about 5 ps) impinging on the target in grazing incidence. For the first time, a complete parametric study was undertaken on the influence of the grazing angle on the pumping of the amplifying medium. One of the results was to reach very high peak brightness about 10 28 ph/s/mm 2 /mrad 2 /(0.1%bandwidth), which compares well with the free-electron laser brightness. Moreover, we modified then used a new two-dimensional hydrodynamic code with adaptive mesh refinement in order to understand the influence of the space-time properties of the infra-red laser on the formation and the evolution of the amplifying plasma. Our modeling highlighted the interest to use a super Gaussian transverse profile for the line focus leading to an increase in a factor two of the gain region size and a reduction of the electron density gradient by three orders of magnitude. These improvements should strongly increase the energy contained in X-UV laser beam. We thus used X-UV laser to study the appearance of transient defects produced by a laser IR on a beam-splitter rear side. We also began research on the mechanisms of DNA damage induced by a very intense X-UV radiation. (author)

  18. Biodistribution and stability studies of [18F]Fluoroethylrhodamine B, a potential PET myocardial perfusion agent

    International Nuclear Information System (INIS)

    Gottumukkala, Vijay; Heinrich, Tobias K.; Baker, Amanda; Dunning, Patricia; Fahey, Frederic H.; Treves, S. Ted; Packard, Alan B.

    2010-01-01

    Introduction: Fluorine-18-labeled rhodamine B was developed as a potential positron emission tomography (PET) tracer for the evaluation of myocardial perfusion, but preliminary studies in mice showed no accumulation in the heart suggesting that it was rapidly hydrolyzed in vivo in mice. A study was therefore undertaken to further evaluate this hypothesis. Methods: [ 18 F]Fluoroethylrhodamine B was equilibrated for 2 h at 37 deg. C in human, rat and mouse serum and in phosphate-buffered saline. Samples were removed periodically and assayed by high-performance liquid chromatography. Based on the results of the stability study, microPET imaging and a biodistribution study were carried out in rats. Results: In vitro stability studies demonstrated that [ 18 F]fluoroethylrhodamine B much more stable in rat and human sera than in mouse serum. After 2 h, the compound was >80% intact in rat serum but 18 F-labeled rhodamines should accumulate in the heart. Conclusions: [ 18 F]Fluoroethylrhodamine B is more stable in rat and human sera than it is in mouse serum. This improved stability is demonstrated by the high uptake of the tracer in the rat heart in comparison to the absence of visible uptake in the mouse heart. These observations suggest that 18 F-labeled rhodamines are promising candidates for more extensive evaluation as PET tracers for the evaluation of myocardial perfusion.

  19. The role of F-18 FDG-PET for 3-D radiation treatment planning of non-small cell lung cancer - first results of a prospective study

    International Nuclear Information System (INIS)

    Schmuecking, M.; Baum, R.P.; Przetak, C.; Niesen, A.; Lopatta, E.C.; Wendt, T.G.; Plichta, K.; Leonhardi, J.

    2001-01-01

    To determine the role of F-18 FDG-PET in 3-D-radiation therapy planning, findings in 27 patients, studied by both, PET and CT, were analyzed prospectively. All patients were first examined by helical CT and F-18 FDG-PET. The PET data were iteratively reconstructed into 3-D images and image fusion with CT data was applied. First, based on CT data, the planning target volumes (PTV) and the volumes of organs at risk were generated. In a second step, the transversal slices of CT and PET were matched. Then, based on PET data, new target volumes were generated. Treatment plans for radiation therapy were calculated on CT-based and PET-based planning target volumes. If PET results were used additionally for the 3-D-planning procedure of radiation therapy, the planning target volume could be reduced in a range of 3-21% as compared with conventional imaging methods, e.g., PET allowed differentiation between tumor and atelectasis resulting in smaller PTV. The dose volume histograms of the PET-based treatment plans showed a reduction of dose to the organs at risk, e.g., V lung (20 Gy) could be reduced by 5% to 17%. In 2 patients, the boost volume based on PET findings was larger than the one based on CT, since PET detected lymph node metastases being of normal size in CT ( [de

  20. Radioligands for PET studies of central benzodiazepine receptors and PK (peripheral benzodiazepine) binding sites -current status

    International Nuclear Information System (INIS)

    Pike, V.W.; Osman, S.; Shah, F.; Turton, D.R.; Waters, S.L.; Crouzel, C.; Nutt, D.J.

    1993-01-01

    The status of the radiochemical development and biological evaluation of radioligands for PET studies of central benzodiazepine (BZ) receptors and the so-called peripheral benzodiazepine binding sites, here discriminated and referred to as PK binding sites, is reviewed against current pharmacological knowledge, indicating those agents with present value and those with future potential. Practical recommendations are given for the preparation of two useful radioligands for PET studies, [N-methyl- 11 C]flumazenil for central BZ receptors, and [N-methyl- 11 C]PK 11195 for PK binding sites. Quality assurance and plasma metabolite analysis are also reviewed for these radioligands and practical recommendations are given on methodology for their performance. (Author)

  1. The Multifactorial Analysis of Static and Repetitive Work. Study of the Work in Services Activities

    Directory of Open Access Journals (Sweden)

    Blanca Andrea Ramírez C.

    2009-04-01

    Full Text Available The office work and specifically the workwith computer are develop in long periods ofstatic work, which is associated with the developmentof muscle skeletal disorders. In consequence,the authors made a transverse studywith office workers (n=377 of a companydedicated to service activities (managementof information and attention to costumersin order to explore the relationship betweenthe work structure, the nature of the tasks and thepresence of muscle skeletal disorders, and toidentify a strategy to stimulate the posturaltransition.The information was collected in a questionpaper that went into variables related to the typeof task that the worker develops, the time that hededicates to office and computer activities, disabilities,medical precedents and current symptomatology.The main medical precedents founded inthe evaluated population was: arterial hypertension(HTA, 8%; lipidomics, 23%; diabetes, 3%,and hypoglycemia, 4%. In the evaluated populationwas found that 80% suffer pain, specificallyrelative to upper limbs: hands, 26%; elbows, 3%,and shoulders 4%. In cervical column, 32%; lumbarcolumn, 16%; and dorsal column, 6%. Finally,it was proved that 80% of the worker’s time isdedicated to static work, specifically to typinginformation.The results of this study are applied to thedevelopment of principles to design tasks andto develop a strategy to promote the posturetransitions at work.

  2. The diagnostic value of 18F-FDG-PET/CT and MRI in suspected vertebral osteomyelitis - a prospective study.

    Science.gov (United States)

    Kouijzer, Ilse J E; Scheper, Henk; de Rooy, Jacky W J; Bloem, Johan L; Janssen, Marcel J R; van den Hoven, Leon; Hosman, Allard J F; Visser, Leo G; Oyen, Wim J G; Bleeker-Rovers, Chantal P; de Geus-Oei, Lioe-Fee

    2018-05-01

    The aim of this study was to determine the diagnostic value of 18 F-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) and magnetic resonance imaging (MRI) in diagnosing vertebral osteomyelitis. From November 2015 until December 2016, 32 patients with suspected vertebral osteomyelitis were prospectively included. All patients underwent both 18 F-FDG-PET/CT and MRI within 48 h. All images were independently reevaluated by two radiologists and two nuclear medicine physicians who were blinded to each others' image interpretation. 18 F-FDG-PET/CT and MRI were compared to the clinical diagnosis according to international guidelines. For 18 F-FDG-PET/CT, sensitivity, specificity, PPV, and NPV in diagnosing vertebral osteomyelitis were 100%, 83.3%, 90.9%, and 100%, respectively. For MRI, sensitivity, specificity, PPV, and NPV were 100%, 91.7%, 95.2%, and 100%, respectively. MRI detected more epidural/spinal abscesses. An important advantage of 18 F-FDG-PET/CT is the detection of metastatic infection (16 patients, 50.0%). 18 F-FDG-PET/CT and MRI are both necessary techniques in diagnosing vertebral osteomyelitis. An important advantage of 18 F-FDG-PET/CT is the visualization of metastatic infection, especially in patients with bacteremia. MRI is more sensitive in detection of small epidural abscesses.

  3. Corticospinal integrity and motor impairment predict outcomes after excitatory repetitive transcranial magnetic stimulation: a preliminary study.

    Science.gov (United States)

    Lai, Chih-Jou; Wang, Chih-Pin; Tsai, Po-Yi; Chan, Rai-Chi; Lin, Shan-Hui; Lin, Fu-Gong; Hsieh, Chin-Yi

    2015-01-01

    To identify the effective predictors for therapeutic outcomes based on intermittent theta-burst stimulation (iTBS). A sham-controlled, double-blind parallel study design. A tertiary hospital. People with stroke (N=72) who presented with unilateral hemiplegia. Ten consecutive sessions of real or sham iTBS were implemented with the aim of enhancing hand function. Patients were categorized into 4 groups according to the presence (MEP+) or absence (MEP-) of motor-evoked potentials (MEPs) and grip strength according to the Medical Research Council (MRC) scale. Cortical excitability, Wolf Motor Function Test (WMFT), finger-tapping task (FT), and simple reaction time were performed before and after the sessions. MEPs and the MRC scale were predictive of iTBS therapeutic outcomes. Group A (MEP+, MRC>1) exhibited the greatest WMFT change (7.6±2.3, P1; 5.2±2.2 score change) and group C (MEP-, MRC=0; 2.3±1.5 score change). These improvements were correlated significantly with baseline motor function and ipsilesional maximum MEP amplitude. The effectiveness of iTBS modulation for poststroke motor enhancement depends on baseline hand grip strength and the presence of MEPs. Our findings indicate that establishing neurostimulation strategies based on the proposed electrophysiological and clinical criteria can allow iTBS to be executed with substantial precision. Effective neuromodulatory strategies can be formulated by using electrophysiological features and clinical presentation information as guidelines. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  4. Using repetitive transcranial magnetic stimulation to study the underlying neural mechanisms of human motor learning and memory.

    Science.gov (United States)

    Censor, Nitzan; Cohen, Leonardo G

    2011-01-01

    In the last two decades, there has been a rapid development in the research of the physiological brain mechanisms underlying human motor learning and memory. While conventional memory research performed on animal models uses intracellular recordings, microfusion of protein inhibitors to specific brain areas and direct induction of focal brain lesions, human research has so far utilized predominantly behavioural approaches and indirect measurements of neural activity. Repetitive transcranial magnetic stimulation (rTMS), a safe non-invasive brain stimulation technique, enables the study of the functional role of specific cortical areas by evaluating the behavioural consequences of selective modulation of activity (excitation or inhibition) on memory generation and consolidation, contributing to the understanding of the neural substrates of motor learning. Depending on the parameters of stimulation, rTMS can also facilitate learning processes, presumably through purposeful modulation of excitability in specific brain regions. rTMS has also been used to gain valuable knowledge regarding the timeline of motor memory formation, from initial encoding to stabilization and long-term retention. In this review, we summarize insights gained using rTMS on the physiological and neural mechanisms of human motor learning and memory. We conclude by suggesting possible future research directions, some with direct clinical implications.

  5. Study of oxygen scavenging PET-based films activated by water

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Gabriella; Scarfato, Paola; Incarnato, Loredana [Department of Industrial Engineering, University of Salerno Via Giovanni Paolo II, 132 - 84084 Fisciano (Italy)

    2016-05-18

    In this work an active barrier system consisting of a thin and transparent film based on polyethylene terephthalate (PET) was studied. Dynamic oxygen absorption measurements were performed at different values of relative humidity and temperature, pointing out that humidity is a key factor in activating the oxidation of the polymer sample. Moreover, the thermal and optical properties of the films were investigated and a good correlation was found between the crystallinity increase and the consequent transparency reduction occurring after the oxygen absorption.

  6. Study of oxygen scavenging PET-based films activated by water

    Science.gov (United States)

    Rossi, Gabriella; Scarfato, Paola; Incarnato, Loredana

    2016-05-01

    In this work an active barrier system consisting of a thin and transparent film based on polyethylene terephthalate (PET) was studied. Dynamic oxygen absorption measurements were performed at different values of relative humidity and temperature, pointing out that humidity is a key factor in activating the oxidation of the polymer sample. Moreover, the thermal and optical properties of the films were investigated and a good correlation was found between the crystallinity increase and the consequent transparency reduction occurring after the oxygen absorption.

  7. Evaluation of MLACF based calculated attenuation brain PET imaging for FDG patient studies

    Science.gov (United States)

    Bal, Harshali; Panin, Vladimir Y.; Platsch, Guenther; Defrise, Michel; Hayden, Charles; Hutton, Chloe; Serrano, Benjamin; Paulmier, Benoit; Casey, Michael E.

    2017-04-01

    Calculating attenuation correction for brain PET imaging rather than using CT presents opportunities for low radiation dose applications such as pediatric imaging and serial scans to monitor disease progression. Our goal is to evaluate the iterative time-of-flight based maximum-likelihood activity and attenuation correction factors estimation (MLACF) method for clinical FDG brain PET imaging. FDG PET/CT brain studies were performed in 57 patients using the Biograph mCT (Siemens) four-ring scanner. The time-of-flight PET sinograms were acquired using the standard clinical protocol consisting of a CT scan followed by 10 min of single-bed PET acquisition. Images were reconstructed using CT-based attenuation correction (CTAC) and used as a gold standard for comparison. Two methods were compared with respect to CTAC: a calculated brain attenuation correction (CBAC) and MLACF based PET reconstruction. Plane-by-plane scaling was performed for MLACF images in order to fix the variable axial scaling observed. The noise structure of the MLACF images was different compared to those obtained using CTAC and the reconstruction required a higher number of iterations to obtain comparable image quality. To analyze the pooled data, each dataset was registered to a standard template and standard regions of interest were extracted. An SUVr analysis of the brain regions of interest showed that CBAC and MLACF were each well correlated with CTAC SUVrs. A plane-by-plane error analysis indicated that there were local differences for both CBAC and MLACF images with respect to CTAC. Mean relative error in the standard regions of interest was less than 5% for both methods and the mean absolute relative errors for both methods were similar (3.4%  ±  3.1% for CBAC and 3.5%  ±  3.1% for MLACF). However, the MLACF method recovered activity adjoining the frontal sinus regions more accurately than CBAC method. The use of plane-by-plane scaling of MLACF images was found to be a

  8. Study of the correlation of IVIM parameter maps with FDG PET

    Energy Technology Data Exchange (ETDEWEB)

    Delso, Gaspar, E-mail: gaspar.delso@usz.ch [GE Healthcare, Waukesha, WI (United States); Lee, Sangwoo [GE Healthcare, Waukesha, WI (United States); Porto, Miguel; Hüllner, Martin; Veit-Haibach, Patrick [Department of Medical Imaging, University Hospital, Zurich (Switzerland)

    2014-01-11

    Intravoxel incoherent motion (IVIM) is a magnetic resonance technique to quantify the influence of microscopic perfusion-related motion and differentiate it from pure molecular diffusion. IVIM has the potential to provide valuable clinical information about microcirculation in the capillary network of healthy tissues as well as malignant tumors. Our goal was to study the correlation of IVIM parameter maps with concurrent FDG-PET data, in view of their potential use in clinical PET/MR protocols. Methods: Data were acquired from ten oncology patients using a tri-modality setup and fitted with a bi-exponential model. The fitting was first solved in the least squares sense and then again using iteratively reweighted least squares. The resulting parameter maps were compared with PET FDG data by an experienced radiologist. Results: Among the pathologies encountered in our patient population were lesions of the liver, spleen, kidney, abdominal wall, prostate and cervix. The qualitative comparison with PET confirmed that IVIM maps provide complementary information about functional inhomogeneity within the tumor. Visual inspection by experienced radiologists showed improved reading of tumor heterogeneity in six of our ten patients when considering FDG uptake together with perfusion fraction maps. The use of a large set of b values was instrumental for data validation and outlier rejection. Robust fitting was shown to increase the accuracy of the fit in 70% of the voxels, leading to average changes of IVIM parametric maps: perfusion fraction f∈[3.9×10{sup –3}, 4.7×10{sup −2}], diffusion coefficient D ∈[−1.2×10{sup −4}, −3.0×10{sup −6}] and pseudo-diffusion coefficient D{sup *}∈[−1.6×10{sup −1}, −9.2×10{sup −3}]. Conclusions: The results suggest that IVIM imaging could be successfully integrated in clinical PET/MR protocols. Clinical validation shows the complementarity of obtained parameter maps with concurrent FDG PET data. Ongoing work is

  9. Performance of a high repetition pulse rate laser system for in-gas-jet laser ionization studies with the Leuven laser ion source LISOL

    International Nuclear Information System (INIS)

    Ferrer, R.; Sonnenschein, V.T.; Bastin, B.; Franchoo, S.; Huyse, M.; Kudryavtsev, Yu.; Kron, T.; Lecesne, N.; Moore, I.D.; Osmond, B.; Pauwels, D.; Radulov, D.; Raeder, S.; Rens, L.

    2012-01-01

    The laser ionization efficiency of the Leuven gas cell-based laser ion source was investigated under on- and off-line conditions using two distinctly different laser setups: a low-repetition rate dye laser system and a high-repetition rate Ti:sapphire laser system. A systematic study of the ion signal dependence on repetition rate and laser pulse energy was performed in off-line tests using stable cobalt and copper isotopes. These studies also included in-gas-jet laser spectroscopy measurements on the hyperfine structure of 63 Cu. A final run under on-line conditions in which the radioactive isotope 59 Cu (T 1/2 = 81.5 s) was produced, showed a comparable yield of the two laser systems for in-gas-cell ionization. However, a significantly improved time overlap by using the high-repetition rate laser system for in-gas-jet ionization was demonstrated by an increase of the overall duty cycle, and at the same time, pointed to the need for a better shaped atomic jet to reach higher ionization efficiencies.

  10. 11C-harmine as a potential PET tracer for ductal pancreas cancer: in vitro studies

    International Nuclear Information System (INIS)

    Herlin, G.; Persson, B.; Laangstroem, B.; Aspelin, P.; Bergstroem, M.

    2003-01-01

    Our objective was to find a tracer in diagnosing human pancreatic cancer using positron emission tomography (PET). For this purpose in vitro test of pancreatic tissues with autoradiography was used. Autoradiography was performed with 11 C-harmine (a MAO-A-inhibitor) with and without competitive inhibition. Tissue preparations were obtained from normal human pancreas and pancreatic cancer. The uptake was compared with rat brain or pig brain, tissues with high expression of MAO-A. Nine autoradiography studies on 16 samples from five different human pancreatic cancers gave a significant level of specific binding of 11 C-harmine in 13, and 3 samples did not give a significant level of specific binding of 11 C-harmine. All 16 samples were analysed with autoradiography. Compared with rat brain, the uptake in the human cancers varied between 9 and 43% except for one tissue preparation which had a too low value for measurement. This study shows expression of MAO-A in human pancreatic cancer. This is readily characterised in vitro. The potential use of 11 C-harmine in the diagnosis of pancreatic cancer using PET might be limited, but further PET studies are necessary. (orig.)

  11. Smoking-induced dopamine release studied with [11C]raclopride PET

    International Nuclear Information System (INIS)

    Kim, Yu Kyeong; Cho, Sang Soo; Lee, Do Hoon

    2005-01-01

    It has been postulated that dopamine release in the striatum underlies the reinforcing properties of nicotine. Substantial evidence in the animal studies demonstrates that nicotine interacts with and regulates the activation of the dopaminergic neuron. The aim of this study was to visualize the dopamine release by smoking in human brain using PET scan with [ 11 C]raclopride. Four male non-smokers or ex-smokers with an abstinence period longer than 1 year (mean age of 24.3±2.6 years) were enrolled in this study. Dopamine D2 receptor radioligand, [ 11 C]raclopride was administrated with bolus-plus-constant infusion. Dynamic PET was performed during 120 minutes (3x20s, 2x60s, 2x120s, 1x180s and 22x300s). Following the 50 minute-scanning, subjects smoked a cigarette containing 1 mg of nicotine while in the scanner. Blood samples for the measurements of plasma nicotine levels were collected at 0, 5, 10, 15, 20, 25, 30, 45, 60, and 90 minute after smoking. Regions for striatal structures were drawn on the coronal summed PET images guided with co-registered MRI. Binding potential, calculated as striatal-cerebellar/cerebellar activity, was measured under equilibrium condition at baseline and smoking session. The mean change in binding potential between the baseline and smoking in caudate, Putamen and ventral striatum was 3.7 % , 4.0 % and 8.6 %, respectively. This indicated the striatal dopamine release by smoking. The reduction in binding potential in the ventral striatum was significantly correlated with the cumulated plasma level of the nicotine (r 2 =0.91, p=0.04). These data demonstrate that in vivo imaging with [ 11 C]raclopride PET could measure nicotine-induced dopamine release in the human brain, which has a significant positive correlation with the amount of nicotine administered by smoking

  12. Parametrically defined cerebral blood vessels as non-invasive blood input functions for brain PET studies

    International Nuclear Information System (INIS)

    Asselin, Marie-Claude; Cunningham, Vincent J; Amano, Shigeko; Gunn, Roger N; Nahmias, Claude

    2004-01-01

    A non-invasive alternative to arterial blood sampling for the generation of a blood input function for brain positron emission tomography (PET) studies is presented. The method aims to extract the dimensions of the blood vessel directly from PET images and to simultaneously correct the radioactivity concentration for partial volume and spillover. This involves simulation of the tomographic imaging process to generate images of different blood vessel and background geometries and selecting the one that best fits, in a least-squares sense, the acquired PET image. A phantom experiment was conducted to validate the method which was then applied to eight subjects injected with 6-[ 18 F]fluoro-L-DOPA and one subject injected with [ 11 C]CO-labelled red blood cells. In the phantom study, the diameter of syringes filled with an 11 C solution and inserted into a water-filled cylinder were estimated with an accuracy of half a pixel (1 mm). The radioactivity concentration was recovered to 100 ± 4% in the 8.7 mm diameter syringe, the one that most closely approximated the superior sagittal sinus. In the human studies, the method systematically overestimated the calibre of the superior sagittal sinus by 2-3 mm compared to measurements made in magnetic resonance venograms on the same subjects. Sources of discrepancies related to the anatomy of the blood vessel were found not to be fundamental limitations to the applicability of the method to human subjects. This method has the potential to provide accurate quantification of blood radioactivity concentration from PET images without the need for blood samples, corrections for delay and dispersion, co-registered anatomical images, or manually defined regions of interest

  13. Smoking-induced dopamine release studied with [{sup 11}C]raclopride PET

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu Kyeong; Cho, Sang Soo; Lee, Do Hoon [Seoul National University College of Medicine, Seoul (Korea, Republic of)] (and others)

    2005-07-01

    It has been postulated that dopamine release in the striatum underlies the reinforcing properties of nicotine. Substantial evidence in the animal studies demonstrates that nicotine interacts with and regulates the activation of the dopaminergic neuron. The aim of this study was to visualize the dopamine release by smoking in human brain using PET scan with [{sup 11}C]raclopride. Four male non-smokers or ex-smokers with an abstinence period longer than 1 year (mean age of 24.3{+-}2.6 years) were enrolled in this study. Dopamine D2 receptor radioligand, [{sup 11}C]raclopride was administrated with bolus-plus-constant infusion. Dynamic PET was performed during 120 minutes (3x20s, 2x60s, 2x120s, 1x180s and 22x300s). Following the 50 minute-scanning, subjects smoked a cigarette containing 1 mg of nicotine while in the scanner. Blood samples for the measurements of plasma nicotine levels were collected at 0, 5, 10, 15, 20, 25, 30, 45, 60, and 90 minute after smoking. Regions for striatal structures were drawn on the coronal summed PET images guided with co-registered MRI. Binding potential, calculated as striatal-cerebellar/cerebellar activity, was measured under equilibrium condition at baseline and smoking session. The mean change in binding potential between the baseline and smoking in caudate, Putamen and ventral striatum was 3.7 % , 4.0 % and 8.6 %, respectively. This indicated the striatal dopamine release by smoking. The reduction in binding potential in the ventral striatum was significantly correlated with the cumulated plasma level of the nicotine (r{sup 2}=0.91, p=0.04). These data demonstrate that in vivo imaging with [{sup 11}C]raclopride PET could measure nicotine-induced dopamine release in the human brain, which has a significant positive correlation with the amount of nicotine administered by smoking.

  14. Methods for the correction of vascular artifacts in PET O-15 water brain-mapping studies

    Science.gov (United States)

    Chen, Kewei; Reiman, E. M.; Lawson, M.; Yun, Lang-sheng; Bandy, D.; Palant, A.

    1996-12-01

    While positron emission tomographic (PET) measurements of regional cerebral blood flow (rCBF) can be used to map brain regions that are involved in normal and pathological human behaviors, measurements in the anteromedial temporal lobe can be confounded by the combined effects of radiotracer activity in neighboring arteries and partial-volume averaging. The authors now describe two simple methods to address this vascular artifact. One method utilizes the early frames of a dynamic PET study, while the other method utilizes a coregistered magnetic resonance image (MRI) to characterize the vascular region of interest (VROI). Both methods subsequently assign a common value to each pixel in the VROI for the control (baseline) scan and the activation scan. To study the vascular artifact and to demonstrate the ability of the proposed methods correcting the vascular artifact, four dynamic PET scans were performed in a single subject during the same behavioral state. For each of the four scans, a vascular scan containing vascular activity was computed as the summation of the images acquired 0-60 s after radiotracer administration, and a control scan containing minimal vascular activity was computed as the summation of the images acquired 20-80 s after radiotracer administration. t-score maps calculated from the four pairs of vascular and control scans were used to characterize regional blood flow differences related to vascular activity before and after the application of each vascular artifact correction method. Both methods eliminated the observed differences in vascular activity, as well as the vascular artifact observed in the anteromedial temporal lobes. Using PET data from a study of normal human emotion, these methods permitted the authors to identify rCBF increases in the anteromedial temporal lobe free from the potentially confounding, combined effects of vascular activity and partial-volume averaging.

  15. Methods for the correction of vascular artifacts in PET O-15 water brain-mapping studies

    International Nuclear Information System (INIS)

    Chen, K.; Reiman, E.M.; Good Samaritan Regional Medical Center, Phoenix, AZ; Lawson, M.; Yun, L.S.; Bandy, D.

    1996-01-01

    While positron emission tomographic (PET) measurements of regional cerebral blood flow (rCBF) can be used to map brain regions that are involved in normal and pathological human behaviors, measurements in the anteromedial temporal lobe can be confounded by the combined effects of radiotracer activity in neighboring arteries and partial-volume averaging. The authors now describe two simple methods to address this vascular artifact. One method utilizes the early frames of a dynamic PET study, while the other method utilizes a coregistered magnetic resonance image (MRI) to characterize the vascular region of interest (VROI). Both methods subsequently assign a common value to each pixel in the VROI for the control scan and the activation scan. To study the vascular artifact and to demonstrate the ability of the proposed methods correcting the vascular artifact, four dynamic PET scans were performed in a single subject during the same behavioral state. For each of the four scans, a vascular scan containing vascular activity was computed as the summation of the images acquired 0--60 s after radiotracer administrations, and a control scan containing minimal vascular activity was computed as the summation of the images acquired 20--80 s after radiotracer administration. t-score maps calculated from the four pairs of vascular and control scans were used to characterize regional blood flow differences related to vascular activity before and after the applications of each vascular artifact correction method. Both methods eliminated the observed differences in vascular activity, as well as the vascular artifact observed in the anteromedial temporal lobes. Using PET data from a study of normal human emotion, these methods permitted us to identify rCBF increases in the anteromedial temporal lobe free from the potentially confounding, combined effects of vascular activity and partial-volume averaging

  16. A PET/MRI study towards finding the optimal ["1"8F]Fluciclovine PET protocol for detection and characterisation of primary prostate cancer

    International Nuclear Information System (INIS)

    Elschot, Mattijs; Sandsmark, Elise; Tessem, May-Britt; Selnaes, Kirsten M.; Bathen, Tone F.; Krueger-Stokke, Brage; Stoerkersen, Oeystein; Moestue, Siver A.; Bertilsson, Helena

    2017-01-01

    ["1"8F]Fluciclovine PET imaging shows promise for the assessment of prostate cancer. The purpose of this PET/MRI study is to optimise the PET imaging protocol for detection and characterisation of primary prostate cancer, by quantitative evaluation of the dynamic uptake of ["1"8F]Fluciclovine in cancerous and benign tissue. Patients diagnosed with high-risk primary prostate cancer underwent an integrated ["1"8F]Fluciclovine PET/MRI exam before robot-assisted radical prostatectomy with extended pelvic lymph node dissection. Volumes-of-interest (VOIs) of selected organs (prostate, bladder, blood pool) and sub-glandular prostate structures (tumour, benign prostatic hyperplasia (BPH), inflammation, healthy tissue) were delineated on T2-weighted MR images, using whole-mount histology samples as a reference. Three candidate windows for optimal PET imaging were identified based on the dynamic curves of the mean and maximum standardised uptake value (SUV_m_e_a_n and SUV_m_a_x, respectively). The statistical significance of differences in SUV between VOIs were analysed using Wilcoxon rank sum tests (p<0.05, adjusted for multiple testing). Twenty-eight (28) patients [median (range) age: 66 (55-72) years] were included. An early (W1: 5-10 minutes post-injection) and two late candidate windows (W2: 18-23; W3: 33-38 minutes post-injection) were selected. Late compared with early imaging was better able to distinguish between malignant and benign tissue [W3, SUV_m_e_a_n: tumour vs. BPH 2.5 vs. 2.0 (p<0.001), tumour vs. inflammation 2.5 vs. 1.7 (p<0.001), tumour vs. healthy tissue 2.5 vs. 2.0 (p<0.001); W1, SUV_m_e_a_n: tumour vs. BPH 3.1 vs. 3.1 (p=0.771), tumour vs inflammation 3.1 vs. 2.2 (p=0.021), tumour vs. healthy tissue 3.1 vs. 2.5 (p<0.001)] as well as between high-grade and low/intermediate-grade tumours (W3, SUV_m_e_a_n: 2.6 vs. 2.1 (p=0.040); W1, SUV_m_e_a_n: 3.1 vs. 2.8 (p=0.173)). These differences were relevant to the peripheral zone, but not the central gland

  17. A PET/MRI study towards finding the optimal [{sup 18}F]Fluciclovine PET protocol for detection and characterisation of primary prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Elschot, Mattijs; Sandsmark, Elise; Tessem, May-Britt [NTNU, Norwegian University of Science and Technology, Deparment of Circulation and Medical Imaging, Faculty of Medicine, Trondheim (Norway); Selnaes, Kirsten M.; Bathen, Tone F. [NTNU, Norwegian University of Science and Technology, Deparment of Circulation and Medical Imaging, Faculty of Medicine, Trondheim (Norway); Trondheim University Hospital, St. Olavs Hospital, Trondheim (Norway); Krueger-Stokke, Brage [NTNU, Norwegian University of Science and Technology, Deparment of Circulation and Medical Imaging, Faculty of Medicine, Trondheim (Norway); Trondheim University Hospital, Department of Radiology, St. Olavs Hospital, Trondheim (Norway); Stoerkersen, Oeystein [Trondheim University Hospital, Department of Pathology, St. Olavs Hospital, Trondheim (Norway); Moestue, Siver A. [NTNU, Norwegian University of Science and Technology, Deparment of Circulation and Medical Imaging, Faculty of Medicine, Trondheim (Norway); NTNU, Norwegian University of Science and Technology, Department of Laboratory Medicine, Children' s and Women' s Health, Faculty of Medicine, Trondheim (Norway); Bertilsson, Helena [Trondheim University Hospital, Department of Urology, St. Olavs Hospital, Trondheim (Norway); NTNU, Norwegian University of Science and Technology, Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Trondheim (Norway)

    2017-04-15

    [{sup 18}F]Fluciclovine PET imaging shows promise for the assessment of prostate cancer. The purpose of this PET/MRI study is to optimise the PET imaging protocol for detection and characterisation of primary prostate cancer, by quantitative evaluation of the dynamic uptake of [{sup 18}F]Fluciclovine in cancerous and benign tissue. Patients diagnosed with high-risk primary prostate cancer underwent an integrated [{sup 18}F]Fluciclovine PET/MRI exam before robot-assisted radical prostatectomy with extended pelvic lymph node dissection. Volumes-of-interest (VOIs) of selected organs (prostate, bladder, blood pool) and sub-glandular prostate structures (tumour, benign prostatic hyperplasia (BPH), inflammation, healthy tissue) were delineated on T2-weighted MR images, using whole-mount histology samples as a reference. Three candidate windows for optimal PET imaging were identified based on the dynamic curves of the mean and maximum standardised uptake value (SUV{sub mean} and SUV{sub max}, respectively). The statistical significance of differences in SUV between VOIs were analysed using Wilcoxon rank sum tests (p<0.05, adjusted for multiple testing). Twenty-eight (28) patients [median (range) age: 66 (55-72) years] were included. An early (W1: 5-10 minutes post-injection) and two late candidate windows (W2: 18-23; W3: 33-38 minutes post-injection) were selected. Late compared with early imaging was better able to distinguish between malignant and benign tissue [W3, SUV{sub mean}: tumour vs. BPH 2.5 vs. 2.0 (p<0.001), tumour vs. inflammation 2.5 vs. 1.7 (p<0.001), tumour vs. healthy tissue 2.5 vs. 2.0 (p<0.001); W1, SUV{sub mean}: tumour vs. BPH 3.1 vs. 3.1 (p=0.771), tumour vs inflammation 3.1 vs. 2.2 (p=0.021), tumour vs. healthy tissue 3.1 vs. 2.5 (p<0.001)] as well as between high-grade and low/intermediate-grade tumours (W3, SUV{sub mean}: 2.6 vs. 2.1 (p=0.040); W1, SUV{sub mean}: 3.1 vs. 2.8 (p=0.173)). These differences were relevant to the peripheral zone, but

  18. A study of commercially-available polyethylene terephthalate (PET) and polycarbonate as nuclear track detector materials

    Science.gov (United States)

    Espinosa, G.; Golzarri, J. I.; Vazquez-Lopez, C.; Trejo, R.; Lopez, K.; Rickards, J.

    2014-07-01

    In the study of the sensitivity of materials to be used as nuclear track detectors, it was found that commercial polyethylene terephthalate (PET) from Ciel® water bottles, commercial roof cover polycarbonate, and recycled packaging strips (recycled PET), can be used as nuclear track detectors. These three commercial materials present nuclear tracks when bombarded by 2.27 MeV nitrogen ions produced in a Pelletron particle accelerator, and by fission fragments from a 252Cf source (79.4 and 103.8 MeV), after a chemical etching with a 6.25M KOH solution, or with a 6.25M KOH solution with 20% methanol, both solutions at 60±1°C. As an example, the nitrogen ions deposit approximately 1 keV/nm in the form of ionization and excitation at the surface of PET, as calculated using the SRIM code. The fission fragments deposit up to 9 keV/nm at the surface, in both cases generating sufficient free radicals to initiate the track formation process. However, 5 MeV alpha particles, typical of radon (222Rn) emissions, deposit only 0.12 keV/nm, do not present tracks after the chemical etching process. This valuable information could be very useful for further studies of new materials in nuclear track methodology.

  19. Effects of a cognitive dual task on variability and local dynamic stability in sustained repetitive arm movements using principal component analysis: a pilot study.

    Science.gov (United States)

    Longo, Alessia; Federolf, Peter; Haid, Thomas; Meulenbroek, Ruud

    2018-06-01

    In many daily jobs, repetitive arm movements are performed for extended periods of time under continuous cognitive demands. Even highly monotonous tasks exhibit an inherent motor variability and subtle fluctuations in movement stability. Variability and stability are different aspects of system dynamics, whose magnitude may be further affected by a cognitive load. Thus, the aim of the study was to explore and compare the effects of a cognitive dual task on the variability and local dynamic stability in a repetitive bimanual task. Thirteen healthy volunteers performed the repetitive motor task with and without a concurrent cognitive task of counting aloud backwards in multiples of three. Upper-body 3D kinematics were collected and postural reconfigurations-the variability related to the volunteer's postural change-were determined through a principal component analysis-based procedure. Subsequently, the most salient component was selected for the analysis of (1) cycle-to-cycle spatial and temporal variability, and (2) local dynamic stability as reflected by the largest Lyapunov exponent. Finally, end-point variability was evaluated as a control measure. The dual cognitive task proved to increase the temporal variability and reduce the local dynamic stability, marginally decrease endpoint variability, and substantially lower the incidence of postural reconfigurations. Particularly, the latter effect is considered to be relevant for the prevention of work-related musculoskeletal disorders since reduced variability in sustained repetitive tasks might increase the risk of overuse injuries.

  20. Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET-MR: Phantom and patient studies

    International Nuclear Information System (INIS)

    Huang, Chuan; Petibon, Yoann; Ouyang, Jinsong; El Fakhri, Georges; Reese, Timothy G.; Ahlman, Mark A.; Bluemke, David A.

    2015-01-01

    relatively accurate motion fields and yield tMR-based motion corrected PET images with similar image quality as those reconstructed using fully sampled tMR data. The reduction of tMR acquisition time makes it more compatible with routine clinical cardiac PET-MR studies

  1. Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET-MR: Phantom and patient studies

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chuan, E-mail: chuan.huang@stonybrookmedicine.edu [Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115 (United States); Departments of Radiology, Psychiatry, Stony Brook Medicine, Stony Brook, New York 11794 (United States); Petibon, Yoann [Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Ouyang, Jinsong; El Fakhri, Georges [Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115 (United States); Reese, Timothy G. [Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115 and Martinos Center for Biomedical Imaging, Charlestown, Massachusetts 02129 (United States); Ahlman, Mark A.; Bluemke, David A. [Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, Maryland 20892 (United States)

    2015-02-15

    relatively accurate motion fields and yield tMR-based motion corrected PET images with similar image quality as those reconstructed using fully sampled tMR data. The reduction of tMR acquisition time makes it more compatible with routine clinical cardiac PET-MR studies.

  2. Study and development of a PET device dedicated to cancer monitoring

    International Nuclear Information System (INIS)

    Vandenbussche, Vincent

    2014-01-01

    Medical imaging first began at the end of the 19. century with the discover of X-rays by Roentgen. Then, numerous imaging modalities have been developed and are used now for a wide range of cases. Positron Emission Tomography (PET) has a high sensitivity, is functional and quantitative, thus being of high interest in cancer monitoring. Nevertheless, PET is not as much spread in hospitals as magnetic resonance imaging and scanner. In this context, this work aims to prove the feasibility of PET dedicated for cancer monitoring. Thanks to instrumental developments such as light sharing in scintillating crystals, use of Silicon Photomultipliers, and an original geometry, cost is expected to be reduced while having same performances as commercial devices. An extensive study of light sharing within scintillating barrels has been made, through many parameters (crystal length, coating, data analysis...). An intrinsic spatial resolution of 4 mm has been measured over a 75 mm long crystal of LYSO, coated with teflon. From such a configuration, a first image has been reconstructed using two modules in coincidence. A spatial resolution of 5 mm has been measured in the image. Finally, Monte Carlo simulations has been made with experimental data as input, in order to measure the performances of the final PET device. Thanks to NEMA standard protocol, performances has been measured and compared to other systems. A spatial resolution of 4 mm has been reached, for a sensitivity of 2.5 cps/kBq. Quantification problem has been assessed, providing results similar to existing devices. (author) [fr

  3. Dynamic PET simulator via tomographic emission projection for kinetic modeling and parametric image studies.

    Science.gov (United States)

    Häggström, Ida; Beattie, Bradley J; Schmidtlein, C Ross

    2016-06-01

    To develop and evaluate a fast and simple tool called dpetstep (Dynamic PET Simulator of Tracers via Emission Projection), for dynamic PET simulations as an alternative to Monte Carlo (MC), useful for educational purposes and evaluation of the effects of the clinical environment, postprocessing choices, etc., on dynamic and parametric images. The tool was developed in matlab using both new and previously reported modules of petstep (PET Simulator of Tracers via Emission Projection). Time activity curves are generated for each voxel of the input parametric image, whereby effects of imaging system blurring, counting noise, scatters, randoms, and attenuation are simulated for each frame. Each frame is then reconstructed into images according to the user specified method, settings, and corrections. Reconstructed images were compared to MC data, and simple Gaussian noised time activity curves (GAUSS). dpetstep was 8000 times faster than MC. Dynamic images from dpetstep had a root mean square error that was within 4% on average of that of MC images, whereas the GAUSS images were within 11%. The average bias in dpetstep and MC images was the same, while GAUSS differed by 3% points. Noise profiles in dpetstep images conformed well to MC images, confirmed visually by scatter plot histograms, and statistically by tumor region of interest histogram comparisons that showed no significant differences (p dynamic PET and parametric images, and demonstrated that it generates both images and subsequent parametric images with very similar noise properties to those of MC images, in a fraction of the time. They believe dpetstep to be very useful for generating fast, simple, and realistic results, however since it uses simple scatter and random models it may not be suitable for studies investigating these phenomena. dpetstep can be downloaded free of cost from https://github.com/CRossSchmidtlein/dPETSTEP.

  4. 64Cu-PSMA-617 PET/CT Imaging of Prostate Adenocarcinoma: First In-Human Studies.

    Science.gov (United States)

    Grubmüller, Bernhard; Baum, Richard P; Capasso, Enza; Singh, Aviral; Ahmadi, Yasaman; Knoll, Peter; Floth, Andreas; Righi, Sergio; Zandieh, Shahin; Meleddu, Carlo; Shariat, Shahrokh F; Klingler, Hans Christoph; Mirzaei, Siroos

    2016-10-07

    The prostate-specific membrane antigen (PSMA) is a cell surface protein, which is overexpressed in nearly all cases of prostate cancer (PCa). PET imaging with 68 Ga-PSMA-HBED-CC has recently found widespread application in the diagnosis of recurrent PCa. In this study, the diagnostic potential of 64 Cu-labeled PSMA ligand (PSMA-617) PET in patients with PCa has been investigated. The study was conducted simultaneously at two nuclear medicine centers, Austria (Vienna, Center 1) and Germany (Bad Berka, Center 2). The patients (n = 29) included in this study were referred for PET (Center 1, 21 patients) or PET/CT (Center 2, 8 patients) imaging with either a high suspicion of recurrent disease or for possible surgical or PSMA radioligand therapy planning. PET images of the whole body were performed at 1 hour p.i. and additional images of the pelvis at 2 hours p.i. In 23 of 29 patients, at least one focus of pathological tracer uptake suspicious for primary disease in the prostate lobe or recurrent disease was detected. Among healthy organs, the salivary glands, kidneys, and liver showed the highest radiotracer uptake. Lesions suspicious for PCa were detected with excellent contrast as early as 1 hour p.i. with high detection rates even at low prostate-specific antigen (PSA) levels. The preliminary results of this study demonstrate the high potential of 64 Cu-PSMA ligand PET/CT imaging in patients with recurrent disease and in the primary staging of selected patients with progressive local disease. The acquired PET images showed an excellent resolution of the detected lesions with very high lesion-to- background contrast. Furthermore, the long half-life of 64 Cu allows distribution of the tracer to clinical PET centers that lack radiochemistry facilities for the preparation of 68 Ga-PSMA ligand (satellite concept).

  5. Repetition and Translation Shifts

    Directory of Open Access Journals (Sweden)

    Simon Zupan

    2006-06-01

    Full Text Available Repetition manifests itself in different ways and at different levels of the text. The first basic type of repetition involves complete recurrences; in which a particular textual feature repeats in its entirety. The second type involves partial recurrences; in which the second repetition of the same textual feature includes certain modifications to the first occurrence. In the article; repetitive patterns in Edgar Allan Poe’s short story “The Fall of the House of Usher” and its Slovene translation; “Konec Usherjeve hiše”; are compared. The author examines different kinds of repetitive patterns. Repetitions are compared at both the micro- and macrostructural levels. As detailed analyses have shown; considerable microstructural translation shifts occur in certain types of repetitive patterns. Since these are not only occasional; sporadic phenomena; but are of a relatively high frequency; they reduce the translated text’s potential for achieving some of the gothic effects. The macrostructural textual property particularly affected by these shifts is the narrator’s experience as described by the narrative; which suffers a reduction in intensity.

  6. A Study on the Basic Criteria for Selecting Heterogeneity Parameters of F18-FDG PET Images

    Science.gov (United States)

    Forgacs, Attila; Pall Jonsson, Hermann; Dahlbom, Magnus; Daver, Freddie; D. DiFranco, Matthew; Opposits, Gabor; K. Krizsan, Aron; Garai, Ildiko; Czernin, Johannes; Varga, Jozsef; Tron, Lajos; Balkay, Laszlo

    2016-01-01

    Textural analysis might give new insights into the quantitative characterization of metabolically active tumors. More than thirty textural parameters have been investigated in former F18-FDG studies already. The purpose of the paper is to declare basic requirements as a selection strategy to identify the most appropriate heterogeneity parameters to measure textural features. Our predefined requirements were: a reliable heterogeneity parameter has to be volume independent, reproducible, and suitable for expressing quantitatively the degree of heterogeneity. Based on this criteria, we compared various suggested measures of homogeneity. A homogeneous cylindrical phantom was measured on three different PET/CT scanners using the commonly used protocol. In addition, a custom-made inhomogeneous tumor insert placed into the NEMA image quality phantom was imaged with a set of acquisition times and several different reconstruction protocols. PET data of 65 patients with proven lung lesions were retrospectively analyzed as well. Four heterogeneity parameters out of 27 were found as the most attractive ones to characterize the textural properties of metabolically active tumors in FDG PET images. These four parameters included Entropy, Contrast, Correlation, and Coefficient of Variation. These parameters were independent of delineated tumor volume (bigger than 25–30 ml), provided reproducible values (relative standard deviation< 10%), and showed high sensitivity to changes in heterogeneity. Phantom measurements are a viable way to test the reliability of heterogeneity parameters that would be of interest to nuclear imaging clinicians. PMID:27736888

  7. Shortened protocol in practical [11C]SA4503-PET studies for sigma1 receptor quantification

    International Nuclear Information System (INIS)

    Sakata, Muneyuki; Kimura, Yuichi; Ishikawa, Masatomo; Oda, Keiichi; Ishii, Kenji; Ishiwata, Kiichi; Naganawa, Mika; Hashimoto, Kenji; Chihara, Kunihiro

    2008-01-01

    In practical positron emission tomography (PET) diagnosis, a shortened protocol is preferred for patients with brain disorders. In this study, the applicability of a shortened protocol as an alternative to the 90-min PET scan with [ 11 C]SA4503 for quantitative sigma 1 receptor measurement was investigated. Tissue time-activity curves of 288 regions of interest in the brain from 32 [ 11 C]SA4503-PET scans of 16 healthy subjects prior to and following administration of a selective serotonin reuptake inhibitor (fluvoxamine or paroxetine) were applied to two algorithms of quantitative analysis; binding potential (BP) was derived from compartmental analysis based on nonlinear estimation, and total distribution volume (tDV) was derived from Logan plot analysis. As a result, although both BP and tDV tended to be underestimated by the shortened method, the estimates from the shortened protocol had good linear relationships with those of the full-length protocol. In conclusion, if approximately 10% differences in the estimated results are acceptable for a specific purpose, then a 60-min measurement protocol is capable of providing reliable results. (author)

  8. Study of CT-based positron range correction in high resolution 3D PET imaging

    Energy Technology Data Exchange (ETDEWEB)

    Cal-Gonzalez, J., E-mail: jacobo@nuclear.fis.ucm.es [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Herraiz, J.L. [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Espana, S. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Vicente, E. [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain); Herranz, E. [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Desco, M. [Unidad de Medicina y Cirugia Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain); Vaquero, J.J. [Dpto. de Bioingenieria e Ingenieria Espacial, Universidad Carlos III, Madrid (Spain); Udias, J.M. [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain)

    2011-08-21

    Positron range limits the spatial resolution of PET images and has a different effect for different isotopes and positron propagation materials. Therefore it is important to consider it during image reconstruction, in order to obtain optimal image quality. Positron range distributions for most common isotopes used in PET in different materials were computed using the Monte Carlo simulations with PeneloPET. The range profiles were introduced into the 3D OSEM image reconstruction software FIRST and employed to blur the image either in the forward projection or in the forward and backward projection. The blurring introduced takes into account the different materials in which the positron propagates. Information on these materials may be obtained, for instance, from a segmentation of a CT image. The results of introducing positron blurring in both forward and backward projection operations was compared to using it only during forward projection. Further, the effect of different shapes of positron range profile in the quality of the reconstructed images with positron range correction was studied. For high positron energy isotopes, the reconstructed images show significant improvement in spatial resolution when positron range is taken into account during reconstruction, compared to reconstructions without positron range modeling.

  9. A Study on the Basic Criteria for Selecting Heterogeneity Parameters of F18-FDG PET Images.

    Directory of Open Access Journals (Sweden)

    Attila Forgacs

    Full Text Available Textural analysis might give new insights into the quantitative characterization of metabolically active tumors. More than thirty textural parameters have been investigated in former F18-FDG studies already. The purpose of the paper is to declare basic requirements as a selection strategy to identify the most appropriate heterogeneity parameters to measure textural features. Our predefined requirements were: a reliable heterogeneity parameter has to be volume independent, reproducible, and suitable for expressing quantitatively the degree of heterogeneity. Based on this criteria, we compared various suggested measures of homogeneity. A homogeneous cylindrical phantom was measured on three different PET/CT scanners using the commonly used protocol. In addition, a custom-made inhomogeneous tumor insert placed into the NEMA image quality phantom was imaged with a set of acquisition times and several different reconstruction protocols. PET data of 65 patients with proven lung lesions were retrospectively analyzed as well. Four heterogeneity parameters out of 27 were found as the most attractive ones to characterize the textural properties of metabolically active tumors in FDG PET images. These four parameters included Entropy, Contrast, Correlation, and Coefficient of Variation. These parameters were independent of delineated tumor volume (bigger than 25-30 ml, provided reproducible values (relative standard deviation< 10%, and showed high sensitivity to changes in heterogeneity. Phantom measurements are a viable way to test the reliability of heterogeneity parameters that would be of interest to nuclear imaging clinicians.

  10. Study of CT-based positron range correction in high resolution 3D PET imaging

    International Nuclear Information System (INIS)

    Cal-Gonzalez, J.; Herraiz, J.L.; Espana, S.; Vicente, E.; Herranz, E.; Desco, M.; Vaquero, J.J.; Udias, J.M.

    2011-01-01

    Positron range limits the spatial resolution of PET images and has a different effect for different isotopes and positron propagation materials. Therefore it is important to consider it during image reconstruction, in order to obtain optimal image quality. Positron range distributions for most common isotopes used in PET in different materials were computed using the Monte Carlo simulations with PeneloPET. The range profiles were introduced into the 3D OSEM image reconstruction software FIRST and employed to blur the image either in the forward projection or in the forward and backward projection. The blurring introduced takes into account the different materials in which the positron propagates. Information on these materials may be obtained, for instance, from a segmentation of a CT image. The results of introducing positron blurring in both forward and backward projection operations was compared to using it only during forward projection. Further, the effect of different shapes of positron range profile in the quality of the reconstructed images with positron range correction was studied. For high positron energy isotopes, the reconstructed images show significant improvement in spatial resolution when positron range is taken into account during reconstruction, compared to reconstructions without positron range modeling.

  11. Correlating subcortical interhemispheric connectivity and cortical hemispheric dominance in brain tumor patients: A repetitive navigated transcranial magnetic stimulation study.

    Science.gov (United States)

    Sollmann, Nico; Ille, Sebastian; Tussis, Lorena; Maurer, Stefanie; Hauck, Theresa; Negwer, Chiara; Bauer, Jan S; Ringel, Florian; Meyer, Bernhard; Krieg, Sandro M

    2016-02-01

    The present study aims to investigate the relationship between transcallosal interhemispheric connectivity (IC) and hemispheric language lateralization by using a novel approach including repetitive navigated transcranial magnetic stimulation (rTMS), hemispheric dominance ratio (HDR) calculation, and rTMS-based diffusion tensor imaging fiber tracking (DTI FT). 31 patients with left-sided perisylvian brain lesions underwent diffusion tensor imaging (DTI) and rTMS language mapping. Cortical language-positive rTMS spots were used to calculate HDRs (HDR: quotient of the left-sided divided by right-sided naming error rates for corresponding left- and right-sided cortical regions) and to create regions of interest (ROIs) for DTI FT. Then, fibers connecting the rTMS-based ROIs of both hemispheres were tracked, and the correlation of IC to HDRs was calculated via Spearman's rank correlation coefficient (rs). Fibers connecting rTMS-based ROIs of both hemispheres were detected in 12 patients (38.7%). Within the patients in which IC was detected, the mean number of subcortical IC fibers ± standard deviation (SD) was 138.0 ± 346.5 (median: 7.5; range: 1-1,217 fibers). Regarding rs for the correlation of HDRs and fiber numbers of patients that showed IC, only moderate correlation was revealed. Our approach might be beneficial and technically feasible for further investigation of the relationship between IC and language lateralization. However, only moderate correlation was revealed in the present study. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Acute and chronic effects of hypercalcaemia on cortical excitability as studied by 5 Hz repetitive transcranial magnetic stimulation.

    Science.gov (United States)

    Iacovelli, Elisa; Gilio, Francesca; Mascia, Maria Lucia; Scillitani, Alfredo; Romagnoli, Elisabetta; Pichiorri, Floriana; Fucile, Sergio; Minisola, Salvatore; Inghilleri, Maurizio

    2011-04-01

    We designed the present study to disclose changes in cortical excitability in humans with hypercalcaemia, by delivering repetitive transcranial magnetic stimulation (rTMS) over the primary motor area (M1). In 22 patients with chronic hypercalcaemia related to primary hyperparathyroidism and 22 age-matched healthy subjects 5 Hz-rTMS was delivered at rest and during a sustained voluntary contraction of the target muscle. Changes in the resting motor threshold (RMT), motor evoked potential (MEP) amplitudes and cortical silent period (CSP) duration were measured and compared in patients and healthy controls. Two of the 22 patients were re-tested after parathyroidectomy when serum calcium had normalized. In a subgroup of healthy subjects, changes in the rTMS parameters were tested before and after acute hypercalcaemia. No significant difference between healthy normocalcaemic subjects and chronic hypercalcaemic patients was found in the RMT values and MEP amplitude and CSP duration evoked by the first stimulus of the trains. During the course of 5 Hz-rTMS trains, MEP size increased significantly less in patients with chronic hypercalcaemia than in healthy subjects, whereas the CSP duration lengthened to a similar extent in both groups. In the two patients studied after parathyroidectomy, rTMS elicited a normal MEP amplitude facilitation. Our findings indicate that acute hypercalcaemia significantly decreased the MEP amplitude facilitation. Given that 5 Hz-rTMS modulates cortical excitability through mechanisms resembling short-term synaptic enhancement, the reduction of MEP amplitude facilitation by hypercalcaemia may be related to Ca2+-dependent changes in synaptic plasticity.

  13. Strategy study of quantification harmonization of SUV in PET/CT images

    International Nuclear Information System (INIS)

    Fischer, Andreia Caroline Fischer da Silveira

    2014-01-01

    In clinical practice, PET/CT images are often analyzed qualitatively by visual comparison of tumor lesions and normal tissues uptake; and semi-quantitatively by means of a parameter called SUV (Standardized Uptake Value). To ensure that longitudinal studies acquired on different scanners are interchangeable, and information of quantification is comparable, it is necessary to establish a strategy to harmonize the quantification of SUV. The aim of this study is to evaluate the strategy to harmonize the quantification of PET/CT images, performed with different scanner models and manufacturers. For this purpose, a survey of the technical characteristics of equipment and acquisition protocols of clinical images of different services of PET/CT in the state of Rio Grande do Sul was conducted. For each scanner, the accuracy of SUV quantification, and the Recovery Coefficient (RC) curves were determined, using the reconstruction parameters clinically relevant and available. From these data, harmonized performance specifications among the evaluated scanners were identified, as well as the algorithm that produces, for each one, the most accurate quantification. Finally, the most appropriate reconstruction parameters to harmonize the SUV quantification in each scanner, either regionally or internationally were identified. It was found that the RC values of the analyzed scanners proved to be overestimated by up to 38%, particularly for objects larger than 17mm. These results demonstrate the need for further optimization, through the reconstruction parameters modification, and even the change of the reconstruction algorithm used in each scanner. It was observed that there is a decoupling between the best image for PET/CT qualitative analysis and the best image for quantification studies. Thus, the choice of reconstruction method should be tied to the purpose of the PET/CT study in question, since the same reconstruction algorithm is not adequate, in one scanner, for qualitative

  14. PET/CT-guided treatment planning for paediatric cancer patients: a simulation study of proton and conventional photon therapy

    DEFF Research Database (Denmark)

    Kornerup, Josefine S.; Brodin, N. P.; Bjork-Eriksson, T.

    2015-01-01

    ) and estimated risk of secondary cancer (SC). RESULTS: Considerable deviations between CT- and PET/CT-guided target volumes were seen in 3 out of the 11 patients studied. However, averaging over the whole cohort, CT or PET/CT guidance introduced no significant difference in the shape or size of the target...... or decreasing irradiated volumes, suggesting that the long-term morbidity of RT in childhood would on average remain largely unaffected. ADVANCES IN KNOWLEDGE: (18)F-FDG PET-based RT planning does not systematically change NTCP or SC risk for paediatric cancer patients compared with CT only. 3 out of 11...... patients had a distinct change of target volumes when PET-guided planning was introduced. Dice and mismatch metrics are not sufficient to assess the consequences of target volume differences in the context of RT....

  15. Medical application of PET technology

    International Nuclear Information System (INIS)

    Lim, Sang Moo; Choi, C. W.; An, S. H.; Woo, K. S.; Chung, W. S.; Yang, S. D.; Jun, G. S. and others

    1999-04-01

    We performed following studies using PET technology: 1. Clinical usefulness of [ 18 F]FDG whole body PET in malignant disease 2. Clinical usefulness of quantitative evaluation of F-18-FDG 3. Pilot study of C-11 methionine PET in brain tumor 4. PET study in patients with Parkinson's disease 5. A study on the clinical myocardial PET image. PET gives various metabolic information for the living human body, and is very important, new diagnostic modality. The PET study will give us the information of cancer patients such as early detection of cancer, staging, recurrence detection and characterization of cancer. The quantitative analysis using PET could be applied to evaluate the pathophysiology of various diseases and develop new drugs and develop new radiopharmaceuticals

  16. Medical application of PET technology

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sang Moo; Choi, C. W.; An, S. H.; Woo, K. S.; Chung, W. S.; Yang, S. D.; Jun, G. S. and others

    1999-04-01

    We performed following studies using PET technology: 1. Clinical usefulness of [{sup 18}F]FDG whole body PET in malignant disease 2. Clinical usefulness of quantitative evaluation of F-18-FDG 3. Pilot study of C-11 methionine PET in brain tumor 4. PET study in patients with Parkinson's disease 5. A study on the clinical myocardial PET image. PET gives various metabolic information for the living human body, and is very important, new diagnostic modality. The PET study will give us the information of cancer patients such as early detection of cancer, staging, recurrence detection and characterization of cancer. The quantitative analysis using PET could be applied to evaluate the pathophysiology of various diseases and develop new drugs and develop new radiopharmaceuticals.

  17. Strategy study of quantification harmonization of SUV in PET/CT images; Estudo da estrategia de harmonizacao da quantificacao do SUV em imagens de PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Andreia Caroline Fischer da Silveira

    2014-07-01

    In clinical practice, PET/CT images are often analyzed qualitatively by visual comparison of tumor lesions and normal tissues uptake; and semi-quantitatively by means of a parameter called SUV (Standardized Uptake Value). To ensure that longitudinal studies acquired on different scanners are interchangeable, and information of quantification is comparable, it is necessary to establish a strategy to harmonize the quantification of SUV. The aim of this study is to evaluate the strategy to harmonize the quantification of PET/CT images, performed with different scanner models and manufacturers. For this purpose, a survey of the technical characteristics of equipment and acquisition protocols of clinical images of different services of PET/CT in the state of Rio Grande do Sul was conducted. For each scanner, the accuracy of SUV quantification, and the Recovery Coefficient (RC) curves were determined, using the reconstruction parameters clinically relevant and available. From these data, harmonized performance specifications among the evaluated scanners were identified, as well as the algorithm that produces, for each one, the most accurate quantification. Finally, the most appropriate reconstruction parameters to harmonize the SUV quantification in each scanner, either regionally or internationally were identified. It was found that the RC values of the analyzed scanners proved to be overestimated by up to 38%, particularly for objects larger than 17mm. These results demonstrate the need for further optimization, through the reconstruction parameters modification, and even the change of the reconstruction algorithm used in each scanner. It was observed that there is a decoupling between the best image for PET/CT qualitative analysis and the best image for quantification studies. Thus, the choice of reconstruction method should be tied to the purpose of the PET/CT study in question, since the same reconstruction algorithm is not adequate, in one scanner, for qualitative

  18. Can repetitive transcranial magnetic stimulation increase muscle strength in functional neurological paresis? A proof-of-principle study.

    Science.gov (United States)

    Broersma, M; Koops, E A; Vroomen, P C; Van der Hoeven, J H; Aleman, A; Leenders, K L; Maurits, N M; van Beilen, M

    2015-05-01

    Therapeutic options are limited in functional neurological paresis disorder. Earlier intervention studies did not control for a placebo effect, hampering assessment of effectivity. A proof-of-principle investigation was conducted into the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS), using a single-blind two-period placebo-controlled cross-over design. Eleven patients received active 15 Hz rTMS over the contralateral motor cortex (hand area), in two periods of 5 days, for 30 min once a day at 80% of resting motor threshold, with a train length of 2 s and an intertrain interval of 4 s. Eight of these eleven patients were also included in the placebo treatment condition. Primary outcome measure was change in muscle strength as measured by dynamometry after treatment. Secondary outcome measure was the subjective change in muscle strength after treatment. In patients who received both treatments, active rTMS induced a significantly larger median increase in objectively measured muscle strength (24%) compared to placebo rTMS (6%; P difference due to treatment, i.e. patients did not perceive these objectively measured motor improvements (P = 0.40). Our findings suggest that rTMS by itself can potentially improve muscle weakness in functional neurological paresis disorder. Whereas patients' muscle strength increased as measured with dynamometry, patients did not report increased functioning of the affected hand, subjectively. The results may indicate that decreased muscle strength is not the core symptom and that rTMS should be added to behavioral approaches in functional neurological paresis. © 2015 EAN.

  19. Cost-effectiveness of FDG-PET in staging non-small cell lung cancer: the PLUS study

    International Nuclear Information System (INIS)

    Verboom, Paul; Grijseels, E.W.M; Uyl-de Groot, Carin A.; Tinteren, Harm van; Diepenhorst, Fred W.; Hoekstra, Otto S.; Smit, Egbert F.; Postmus, Pieter E.; Bergh, Jan H.A.M. van den; Velthoven, Piet C.M. van; Schreurs, Ad J.M.; Stallaert, Roland A.L.M.; Comans, Emile F.I.; Teule, Gerrit J.J.; Mourik, Johan C. van; Boers, Maarten

    2003-01-01

    Currently, up to 50% of the operations in early-stage non-small cell lung cancer (NSCLC) are futile owing to the presence of locally advanced tumour or distant metastases. More accurate pre-operative staging is required in order to reduce the number of futile operations. The cost-effectiveness of fluorine-18 fluorodeoxyglucose positron emission tomography ( 18 FDG-PET) added to the conventional diagnostic work-up was studied in the PLUS study. Prior to invasive staging and/or thoracotomy, 188 patients with (suspected) NSCLC were randomly assigned to conventional work-up (CWU) and whole-body PET or to CWU alone. CWU was based on prevailing guidelines. Pre-operative staging was followed by 1 year of follow-up. Outcomes are expressed in the percentage of correctly staged patients and the associated costs. The cost price of PET varied between and euro;736 and and euro;1,588 depending on the (hospital) setting and the procurement of 18 FDG commercially or from on-site production. In the CWU group, 41% of the patients underwent a futile thoracotomy, whereas in the PET group 21% of the thoracotomies were considered futile (P=0.003). The average costs per patient in the CWU group were and euro;9,573 and in the PET group, and euro;8,284. The major cost driver was the number of hospital days related to recovery from surgery. Sensitivity analysis on the cost and accuracy of PET showed that the results were robust, i.e. in favour of the PET group. The addition of PET to CWU prevented futile surgery in one out of five patients with suspected NSCLC. Despite the additional PET costs, the total costs were lower in the PET group, mainly due to a reduction in the number of futile operations. The additional use of PET in the staging of patients with NSCLC is feasible, safe and cost saving from a clinical and from an economic perspective. (orig.)

  20. A Method for Manufacturing Oncological Phantoms for the Quantification of 18F-FDG PET and DW-MRI Studies

    Directory of Open Access Journals (Sweden)

    Francesca Gallivanone

    2017-01-01

    Full Text Available The aim of this work was to develop a method to manufacture oncological phantoms for quantitation purposes in 18F-FDG PET and DW-MRI studies. Radioactive and diffusion materials were prepared using a mixture of agarose and sucrose radioactive gels. T2 relaxation and diffusion properties of gels at different sucrose concentrations were evaluated. Realistic oncological lesions were created using 3D-printed plastic molds filled with the gel mixture. Once solidified, gels were extracted from molds and immersed in a low-radioactivity gel simulating normal background tissue. A breast cancer phantom was manufactured using the proposed method as an exploratory feasibility study, including several realistic oncological configurations in terms of both radioactivity and diffusion. The phantom was acquired in PET with 18F-FDG, immediately after solidification, and in DW-MRI the following day. Functional volumes characterizing the simulated BC lesions were segmented from PET and DW-MRI images. Measured radioactive uptake and ADC values were compared with gold standards. Phantom preparation was straightforward, and the time schedule was compatible with both PET and MRI measurements. Lesions appeared on 18F-FDG PET and DW-MRI images as expected, without visible artifacts. Lesion functional parameters revealed the phantom’s potential for validating quantification methods, in particular for new generation hybrid PET-MRI systems.

  1. Repetitive Questioning Exasperates Caregivers

    Directory of Open Access Journals (Sweden)

    R. C. Hamdy MD

    2018-01-01

    Full Text Available Repetitive questioning is due to an impaired episodic memory and is a frequent, often presenting, problem in patients with Alzheimer’s disease (amnestic type. It is due to the patients’ difficulties learning new information, retaining it, and recalling it, and is often aggravated by a poor attention span and easy distractibility. A number of factors may trigger and maintain repetitive questioning. Caregivers should try to identify and address these triggers. In the case discussion presented, it is due to the patient’s concerns about her and her family’s safety triggered by watching a particularly violent movie aired on TV. What went wrong in the patient/caregiver interaction and how it could have been avoided or averted are explored. Also reviewed are the impact of repetitive questioning, the challenges it raises for caregivers, and some effective intervention strategies that may be useful to diffuse the angst that caregivers experience with repetitive questioning.

  2. Global Repetition Influences Contextual Cueing

    Science.gov (United States)

    Zang, Xuelian; Zinchenko, Artyom; Jia, Lina; Li, Hong

    2018-01-01

    Our visual system has a striking ability to improve visual search based on the learning of repeated ambient regularities, an effect named contextual cueing. Whereas most of the previous studies investigated contextual cueing effect with the same number of repeated and non-repeated search displays per block, the current study focused on whether a global repetition frequency formed by different presentation ratios between the repeated and non-repeated configurations influence contextual cueing effect. Specifically, the number of repeated and non-repeated displays presented in each block was manipulated: 12:12, 20:4, 4:20, and 4:4 in Experiments 1–4, respectively. The results revealed a significant contextual cueing effect when the global repetition frequency is high (≥1:1 ratio) in Experiments 1, 2, and 4, given that processing of repeated displays was expedited relative to non-repeated displays. Nevertheless, the contextual cueing effect reduced to a non-significant level when the repetition frequency reduced to 4:20 in Experiment 3. These results suggested that the presentation frequency of repeated relative to the non-repeated displays could influence the strength of contextual cueing. In other words, global repetition statistics could be a crucial factor to mediate contextual cueing effect. PMID:29636716

  3. Grade Repetition in Queensland State Prep Classes

    Science.gov (United States)

    Anderson, Robyn

    2012-01-01

    The current study considers grade repetition rates in the early years of schooling in Queensland state schools with specific focus on the pre-schooling year, Prep. In particular, it provides empirical evidence of grade repetition in Queensland state schools along with groups of students who are more often repeated. At the same time, much of the…

  4. Attenuation correction for hybrid MR/PET scanners: a comparison study

    Energy Technology Data Exchange (ETDEWEB)

    Rota Kops, Elena [Forschungszentrum Jülich GmbH, Jülich (Germany); Ribeiro, Andre Santos [Imperial College London, London (United Kingdom); Caldeira, Liliana [Forschungszentrum Jülich GmbH, Jülich (Germany); Hautzel, Hubertus [Heinrich-Heine-University Düsseldorf, Düsseldorf (Germany); Lukas, Mathias [Technische Universitaet Muenchen, Munich (Germany); Antoch, Gerald [Heinrich-Heine-University Düsseldorf, Düsseldorf (Germany); Lerche, Christoph; Shah, Jon [Forschungszentrum Jülich GmbH, Jülich (Germany)

    2015-05-18

    Attenuation correction of PET data acquired in hybrid MR/PET scanners is still a challenge. Different methods have been adopted by several groups to obtain reliable attenuation maps (mu-maps). In this study we compare three methods: MGH, UCL, Neural-Network. The MGH method is based on an MR/CT template obtained with the SPM8 software. The UCL method uses a database of MR/CT pairs. Both generate mu-maps from MP-RAGE images. The feed-forward neural-network from Juelich (NN-Juelich) requires two UTE images; it generates segmented mu-maps. Data from eight subjects (S1-S8) measured in the Siemens 3T MR-BrainPET scanner were used. Corresponding CT images were acquired. The resulting mu-maps were compared against the CT-based mu-maps for each subject and method. Overlapped voxels and Dice similarity coefficients, D, for bone, soft-tissue and air regions, and relative differences images were calculated. The true positive (TP) recognized voxels for the whole head were 79.9% (NN-Juelich, S7) to 92.1% (UCL method, S1). D values of the bone were D=0.65 (NN-Juelich, S1) to D=0.87 (UCL method, S1). For S8 the MHG method failed (TP=76.4%; D=0.46 for bone). D values shared a common tendency in all subjects and methods to recognize soft-tissue as bone. The relative difference images showed a variation of -10.9% - +10.1%; for S8 and MHG method the values were -24.5% and +14.2%. A preliminary comparison of three methods for generation of mu-maps for MR/PET scanners is presented. The continuous methods (MGH, UCL) seem to generate reliable mu-maps, whilst the binary method seems to need further improvement. Future work will include more subjects, the reconstruction of corresponding PET data and their comparison.

  5. Attenuation correction for hybrid MR/PET scanners: a comparison study

    International Nuclear Information System (INIS)

    Rota Kops, Elena; Ribeiro, Andre Santos; Caldeira, Liliana; Hautzel, Hubertus; Lukas, Mathias; Antoch, Gerald; Lerche, Christoph; Shah, Jon

    2015-01-01

    Attenuation correction of PET data acquired in hybrid MR/PET scanners is still a challenge. Different methods have been adopted by several groups to obtain reliable attenuation maps (mu-maps). In this study we compare three methods: MGH, UCL, Neural-Network. The MGH method is based on an MR/CT template obtained with the SPM8 software. The UCL method uses a database of MR/CT pairs. Both generate mu-maps from MP-RAGE images. The feed-forward neural-network from Juelich (NN-Juelich) requires two UTE images; it generates segmented mu-maps. Data from eight subjects (S1-S8) measured in the Siemens 3T MR-BrainPET scanner were used. Corresponding CT images were acquired. The resulting mu-maps were compared against the CT-based mu-maps for each subject and method. Overlapped voxels and Dice similarity coefficients, D, for bone, soft-tissue and air regions, and relative differences images were calculated. The true positive (TP) recognized voxels for the whole head were 79.9% (NN-Juelich, S7) to 92.1% (UCL method, S1). D values of the bone were D=0.65 (NN-Juelich, S1) to D=0.87 (UCL method, S1). For S8 the MHG method failed (TP=76.4%; D=0.46 for bone). D values shared a common tendency in all subjects and methods to recognize soft-tissue as bone. The relative difference images showed a variation of -10.9% - +10.1%; for S8 and MHG method the values were -24.5% and +14.2%. A preliminary comparison of three methods for generation of mu-maps for MR/PET scanners is presented. The continuous methods (MGH, UCL) seem to generate reliable mu-maps, whilst the binary method seems to need further improvement. Future work will include more subjects, the reconstruction of corresponding PET data and their comparison.

  6. First in situ TOF-PET study using digital photon counters for proton range verification.

    Science.gov (United States)

    Cambraia Lopes, P; Bauer, J; Salomon, A; Rinaldi, I; Tabacchini, V; Tessonnier, T; Crespo, P; Parodi, K; Schaart, D R

    2016-08-21

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong (15)O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  10(8) protons s(-1), and 10(10) total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results

  7. Flutriciclamide (18F-GE180) PET: First-in-Human PET Study of Novel Third-Generation In Vivo Marker of Human Translocator Protein.

    Science.gov (United States)

    Fan, Zhen; Calsolaro, Valeria; Atkinson, Rebecca A; Femminella, Grazia D; Waldman, Adam; Buckley, Christopher; Trigg, William; Brooks, David J; Hinz, Rainer; Edison, Paul

    2016-11-01

    Neuroinflammation is associated with neurodegenerative disease. PET radioligands targeting the 18-kDa translocator protein (TSPO) have been used as in vivo markers of neuroinflammation, but there is an urgent need for novel probes with improved signal-to-noise ratio. Flutriciclamide ( 18 F-GE180) is a recently developed third-generation TSPO ligand. In this first study, we evaluated the optimum scan duration and kinetic modeling strategies for 18 F-GE180 PET in (older) healthy controls. Ten healthy controls, 6 TSPO high-affinity binders, and 4 mixed-affinity binders were recruited. All subjects underwent detailed neuropsychologic tests, MRI, and a 210-min 18 F-GE180 dynamic PET/CT scan using metabolite-corrected arterial plasma input function. We evaluated 5 different kinetic models: irreversible and reversible 2-tissue-compartment models, a reversible 1-tissue model, and 2 models with an extra irreversible vascular compartment. The minimal scan duration was established using 210-min scan data. The feasibility of generating parametric maps was also investigated using graphical analysis. 18 F-GE180 concentration was higher in plasma than in whole blood during the entire scan duration. The volume of distribution (V T ) was 0.17 in high-affinity binders and 0.12 in mixed-affinity binders using the kinetic model. The model that best represented brain 18 F-GE180 kinetics across regions was the reversible 2-tissue-compartment model (2TCM4k), and 90 min resulted as the optimum scan length required to obtain stable estimates. Logan graphical analysis with arterial input function gave a V T highly consistent with V T in the kinetic model, which could be used for voxelwise analysis. We report for the first time, to our knowledge, the kinetic properties of the novel third-generation TSPO PET ligand 18 F-GE180 in humans: 2TCM4k is the optimal method to quantify the brain uptake, 90 min is the optimal scan length, and the Logan approach could be used to generate parametric maps

  8. Specification and estimation of sources of bias affecting neurological studies in PET/MR with an anatomical brain phantom

    Science.gov (United States)

    Teuho, J.; Johansson, J.; Linden, J.; Saunavaara, V.; Tolvanen, T.; Teräs, M.

    2014-01-01

    Selection of reconstruction parameters has an effect on the image quantification in PET, with an additional contribution from a scanner-specific attenuation correction method. For achieving comparable results in inter- and intra-center comparisons, any existing quantitative differences should be identified and compensated for. In this study, a comparison between PET, PET/CT and PET/MR is performed by using an anatomical brain phantom, to identify and measure the amount of bias caused due to differences in reconstruction and attenuation correction methods especially in PET/MR. Differences were estimated by using visual, qualitative and quantitative analysis. The qualitative analysis consisted of a line profile analysis for measuring the reproduction of anatomical structures and the contribution of the amount of iterations to image contrast. The quantitative analysis consisted of measurement and comparison of 10 anatomical VOIs, where the HRRT was considered as the reference. All scanners reproduced the main anatomical structures of the phantom adequately, although the image contrast on the PET/MR was inferior when using a default clinical brain protocol. Image contrast was improved by increasing the amount of iterations from 2 to 5 while using 33 subsets. Furthermore, a PET/MR-specific bias was detected, which resulted in underestimation of the activity values in anatomical structures closest to the skull, due to the MR-derived attenuation map that ignores the bone. Thus, further improvements for the PET/MR reconstruction and attenuation correction could be achieved by optimization of RAMLA-specific reconstruction parameters and implementation of bone to the attenuation template.

  9. A prospective PET study of patients with glioblastoma multiforme

    DEFF Research Database (Denmark)

    Andersen, Preben B.; Blinkenberg, M; Lassen, U

    2006-01-01

    OBJECTIVE: To study the post-surgical metabolic and structural cerebral changes in patients with glioblastoma multiforme (GBM). MATERIALS AND METHODS: We examined ten patients prospectively with newly diagnosed GBM. All patients were primarily treated with surgery, followed by chemotherapy...... compared with structural imaging in the prospective evaluation of GBM. We found a difference in metabolic increase and tumor growth between the two treatment regimens, although this finding has limited relevance due to the design of the study....

  10. Simulation Study of PET System Using GATE%基于GATE的PET系统仿真研究

    Institute of Scientific and Technical Information of China (English)

    刘豪佳; 张斌

    2014-01-01

    PET and SPECT is the most advanced nuclear medical imaging technology .GATE is a dedicated Monte Carlo simulation platform for PET and SPECT .This study validates two GATE models of Simens ECAT EXACT HR+PET scanner and Simens PET/CT Biograph 2.After the simulation of PET systems completed , testing and performance evaluation of simulation systems were proceeded according to NEMA 2001 performance protocols , including spatial resolution , scatter fraction and sensitivity .Test results show that , performances of GATE simulation systems agree well with the experimental values .%PET和SPECT是现代核医学最高水平的影像技术,GATE是专用于PET和SPECT的蒙特卡罗仿真工具。研究以西门子公司的PET扫描仪 ECAT EXACT HR+和PET/CT Biograph2为原型,分别使用GATE实现其系统的完整仿真。依据NEMA 2001标准,对仿真系统的空间分辨率、散射分数和灵敏度分别进行测试与评估。测试结果表明,仿真系统性能参数和实验结果之间具有良好的一致性。

  11. Study of the structure of polyethyleneterphtalate (PET) films

    International Nuclear Information System (INIS)

    Melinte, S.; Leanca, M.; Moise, M.; Mateescu, N.

    1979-01-01

    In the process of polymer stretching, there occur structural modifications (detected by X-ray diffraction) which are reflected in the superstructure, as revealed by electron microscopy. The paper studies three types of polyethyleneterphtalate films, taken from the stages of the technological process of obtention of two-way stretched films: extruded ones, one-way stretched ones and two-way stretched ones. (author)

  12. Transcutaneous Auricular Vagus Nerve Stimulation with Concurrent Upper Limb Repetitive Task Practice for Poststroke Motor Recovery: A Pilot Study.

    Science.gov (United States)

    Redgrave, Jessica N; Moore, Lucy; Oyekunle, Tosin; Ebrahim, Maryam; Falidas, Konstantinos; Snowdon, Nicola; Ali, Ali; Majid, Arshad

    2018-03-23

    Invasive vagus nerve stimulation (VNS) has the potential to enhance the effects of physiotherapy for upper limb motor recovery after stroke. Noninvasive, transcutaneous auricular branch VNS (taVNS) may have similar benefits, but this has not been evaluated in stroke recovery. We sought to determine the feasibility of taVNS delivered alongside upper limb repetitive task-specific practice after stroke and its effects on a range of outcome measures evaluating limb function. Thirteen participants at more than 3 months postischemic stroke with residual upper limb dysfunction were recruited from the community of Sheffield, United Kingdom (October-December 2016). Participants underwent 18 × 1-hour sessions over 6 weeks in which they made 30-50 repetitions of 8-10 arm movements concurrently with taVNS (NEMOS; Cerbomed, Erlangen, Germany, 25 Hz, .1-millisecond pulse width) at maximum tolerated intensity (mA). An electrocardiogram and rehabilitation outcome scores were obtained at each visit. Qualitative interviews determined the acceptability of taVNS to participants. Median time after stroke was 1.16 years, and baseline median/interquartile range upper limb Fugl-Meyer (UFM) score was 63 (54.5-99.5). Participants attended 92% of the planned treatment sessions. Three participants reported side effects, mainly fatigue, but all performed mean of more than 300 arm repetitions per session with no serious adverse events. There was a significant change in the UFM score with a mean increase per participant of 17.1 points (standard deviation 7.8). taVNS is feasible and well-tolerated alongside upper limb repetitive movements in poststroke rehabilitation. The motor improvements observed justify a phase 2 trial in patients with residual arm weakness. Copyright © 2018 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  13. REPETITIVE STRENGTH AMONG STUDENTS OF AGE 14

    Directory of Open Access Journals (Sweden)

    Besim Halilaj

    2014-06-01

    Full Text Available The study involved 82 male students of the primary school “Qamil Ilazi” in Kaçanik-Kosovo.Four movement tests, which test the repetitive strength, were conducted: 1. Pull-up, 2. Sit-Up, 3. Back extension, 4. Push-up.The main goal of this study was to verify the actual motor status, respectively the component of the repetitive strength among students of age 14 of masculine gender. In addition to verifying the actual motor status, another objective was to verify the relationship between the variables employed.Basic statistical parameters show a distribution which is not significantly different from the normal distribution, yielded highly correlative values among the repetitive strength tests. Space factorization resulted in extracting two latent squares defined as repetitive strength of arms factor, and repetitive strength of body factor.

  14. DNA Fingerprinting of Lactobacillus crispatus Strain CTV-05 by Repetitive Element Sequence-Based PCR Analysis in a Pilot Study of Vaginal Colonization

    OpenAIRE

    Antonio, May A. D.; Hillier, Sharon L.

    2003-01-01

    Lactobacillus crispatus is one of the predominant hydrogen peroxide (H2O2)-producing species found in the vagina and is under development as a probiotic for the treatment of bacterial vaginosis. In this study, we assessed whether DNA fingerprinting by repetitive element sequence-based PCR (rep-PCR) can be used to distinguish the capsule strain of L. crispatus (CTV-05) from other endogenous strains as well as other species of vaginal lactobacilli. Vaginal and rectal lactobacilli were identifie...

  15. Role of 68Ga somatostatin receptor PET/CT in the detection of endogenous hyperinsulinaemic focus: an explorative study

    International Nuclear Information System (INIS)

    Prasad, Vikas; Sainz-Esteban, Aurora; Arsenic, Ruza; Ploeckinger, Ursula; Denecke, Timm; Pape, Ulrich-Frank; Pavel, Marianne; Pascher, Andreas; Kuehnen, Peter; Blankenstein, Oliver

    2016-01-01

    To explore the role of 68 Ga-DOTATATE/DOTATOC PET/CT (SR PET/CT) in patients with suspicion of or histopathologically proven pancreatogenic hyperinsulinaemic hypoglycaemia. We included 13 patients with histopathologically proven or a high clinical suspicion of pancreatogenic hyperinsulinaemia. All the patients underwent a SR PET/CT scan. The results were correlated with histopathological findings. Normalization of blood glucose levels after resection of the pancreatic lesion, as well as a cytological and/or pathological diagnosis of insulinoma, was considered the diagnostic gold standard for insulinoma. The diagnosis of nesidioblastosis was based on exclusion of an insulinoma and conclusive pathological examination of a segment of the pancreas. Malignant insulinoma was defined as the presence of locoregional or distant metastases. Based on histopathology, 13 patients were found to have pancreatic hyperinsulinaemia: two patients had malignant insulinoma, eight had nonmetastasized insulinoma, and three had nesidioblastosis. SR PET was positive in 11 of the 13 patients (84.6 %) with a final diagnosis of endogenous pancreatic hypoglycaemia. Histopathological staining confirmed 16 foci of hyperinsulinism (insulin positivity). SR PET detected 14 of the 16 lesions, resulting in a sensitivity of 87 %. One intrapancreatic spleen was falsely diagnosed as insulinoma focus on SR PET, resulting in positive predictive value of 93.3 %. Immunohistochemical staining of somatostatin receptor (SSR) subtype 2a was available in ten specimens: two nesidioblastosis, and seven benign and one malignant insulinoma. Eight out of the ten specimens (80 %) stained strongly to moderately positive. Seven of the eight SSR2a-positive lesions were picked up on SR PET. Based on the results of SR PET/CT, nine patients achieved complete remission of the hypoglycaemic events during follow-up. This explorative study suggests that SR PET in combination with CT may play a significant role in the detection

  16. Accuracy and Radiation Dose of CT-Based Attenuation Correction for Small Animal PET: A Monte Carlo Simulation Study

    International Nuclear Information System (INIS)

    Yang, Ching-Ching; Chan, Kai-Chieh

    2013-06-01

    -Small animal PET allows qualitative assessment and quantitative measurement of biochemical processes in vivo, but the accuracy and reproducibility of imaging results can be affected by several parameters. The first aim of this study was to investigate the performance of different CT-based attenuation correction strategies and assess the resulting impact on PET images. The absorbed dose in different tissues caused by scanning procedures was also discussed to minimize biologic damage generated by radiation exposure due to PET/CT scanning. A small animal PET/CT system was modeled based on Monte Carlo simulation to generate imaging results and dose distribution. Three energy mapping methods, including the bilinear scaling method, the dual-energy method and the hybrid method which combines the kVp conversion and the dual-energy method, were investigated comparatively through assessing the accuracy of estimating linear attenuation coefficient at 511 keV and the bias introduced into PET quantification results due to CT-based attenuation correction. Our results showed that the hybrid method outperformed the bilinear scaling method, while the dual-energy method achieved the highest accuracy among the three energy mapping methods. Overall, the accuracy of PET quantification results have similar trend as that for the estimation of linear attenuation coefficients, whereas the differences between the three methods are more obvious in the estimation of linear attenuation coefficients than in the PET quantification results. With regards to radiation exposure from CT, the absorbed dose ranged between 7.29-45.58 mGy for 50-kVp scan and between 6.61-39.28 mGy for 80-kVp scan. For 18 F radioactivity concentration of 1.86x10 5 Bq/ml, the PET absorbed dose was around 24 cGy for tumor with a target-to-background ratio of 8. The radiation levels for CT scans are not lethal to the animal, but concurrent use of PET in longitudinal study can increase the risk of biological effects. The

  17. Brain metabolic changes in Hodgkin disease patients following diagnosis and during the disease course: An 18F-FDG PET/CT study.

    Science.gov (United States)

    Chiaravalloti, Agostino; Pagani, Marco; Cantonetti, Maria; DI Pietro, Barbara; Tavolozza, Mario; Travascio, Laura; DI Biagio, Daniele; Danieli, Roberta; Schillaci, Orazio

    2015-02-01

    The aim of the present study was to investigate brain glucose metabolism in patients with Hodgkin disease (HD) after diagnosis and during chemotherapy treatment. Following the administration of first-line doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) chemotherapy, 74 HD patients underwent 18 F-fluoro-2-deoxy-D-glucose ( 18 F-FDG) positron emission tomography (PET)/computed tomography brain scans, both baseline (PET0) and interim (PET2) at the Department of Biomedicine and Prevention, University of Rome Tor Vergata (Rome, Italy). Fifty-seven patients were further evaluated 15±6 days after four additional cycles (PET6). Furthermore, a control group (CG) of 40 chemotherapy-naïve subjects was enrolled. Differences in brain 18 F-FDG uptake between the CG, PET0, PET2 and PET6 scans were analyzed using statistical parametric mapping. Compared with the PET0 and CG scans, the PET2 scan demonstrated a higher metabolic activity in Brodmann area (BA) 39, and a metabolic reduction in BA 11 bilaterally and in left BA 32. All of these changes disappeared at PET6. The results of the present study indicate that ABVD chemotherapy has a limited impact on brain metabolism.

  18. Risk factors associated with repetition of self-harm in black and minority ethnic (BME) groups: a multi-centre cohort study.

    Science.gov (United States)

    Cooper, Jayne; Steeg, Sarah; Webb, Roger; Stewart, Suzanne L K; Applegate, Eve; Hawton, Keith; Bergen, Helen; Waters, Keith; Kapur, Navneet

    2013-06-01

    Little information is available to inform clinical assessments on risk of self-harm repetition in ethnic minority groups. In a prospective cohort study, using data collected from six hospitals in England for self-harm presentations occurring between 2000 and 2007, we investigated risk factors for repeat self-harm in South Asian and Black people in comparison to Whites. During the study period, 751 South Asian, 468 Black and 15,705 White people presented with self-harm in the study centres. Repeat self-harm occurred in 4379 individuals, which included 229 suicides (with eight of these fatalities being in the ethnic minority groups). The risk ratios for repetition in the South Asian and Black groups compared to the White group were 0.6, 95% CI 0.5-0.7 and 0.7, 95% CI 0.5-0.8, respectively. Risk factors for repetition were similar across all three groups, although excess risk versus Whites was seen in Black people presenting with mental health symptoms, and South Asian people reporting alcohol use and not having a partner. Additional modelling of repeat self-harm count data showed that alcohol misuse was especially strongly linked with multiple repetitions in both BME groups. Ethnicity was not recorded in a third of cases which may introduce selection bias. Differences may exist due to cultural diversity within the broad ethnic groups. Known social and psychological features that infer risk were present in South Asian and Black people who repeated self-harm. Clinical assessment in these ethnic groups should ensure recognition and treatment of mental illness and alcohol misuse. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Cochlear implant benefits in deafness rehabilitation: PET study of temporal voice Activations

    Energy Technology Data Exchange (ETDEWEB)

    Coez, A.; Zilbovicius, M. [CEA, Serv Hosp Frederic Joliot, INSERM, Res Unit Neuroimaging and Psychiat, U797, IFR49, F-91406 Orsay (France); Zilbovicius, M.; Syrota, A.; Samson, Y. [CEA, DSV, DRM, Serv Hosp Frederic Joliot, F-91406 Orsay (France); Bizaguet, E. [Lab Correct Audit, Paris (France); Coez, A. [Univ Paris Sud 11, Paris (France); Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O. [INSERM, Unit M 867, Paris (France); Ambert-Dahan, E. [Hop Beaujon, Serv ORL Chirurg Cervicofaciale, AP-HP, Clichy (France); Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O. [Inst Fed Rech Claude Bernard Physiol et Pathol, IFR02, Paris (France); Samson, Y. [Hop La Pitie Salpetriere, Serv Urgences Cerebro-vasc, AP-HP, Paris (France); Samson, Y. [Univ Paris 06, Paris (France); Sterkers, O. [Univ Denis Diderot Paris 7, Paris (France)

    2008-07-01

    Cochlear implants may improve the medical and social prognosis of profound deafness. Nevertheless, some patients have experienced poor results without any clear explanations. One correlate may be an alteration in cortical voice processing. To test this hypothesis, we studied the activation of human temporal voice areas (TVA) using a well-standardized PET paradigm adapted from previous functional MRI (fMRI) studies. Methods: A PET H{sub 2}{sup 15}O activation study was performed on 3 groups of adult volunteers: normal-hearing control subjects (n 6) and cochlear-implanted post-lingually deaf patients with {>=}2 y of cochlear implant experience, with intelligibility scores in the 'Lafon monosyllabic task' {>=}80% (Good group; n 6) or {<=}20% (Poor group; n 6). Relative cerebral blood flow was measured in 3 conditions: rest, passive listening to human voice, and non-voice stimuli. Results: Compared with silence, the activations induced by non-voice stimuli were bilaterally located in the superior temporal regions in all groups. However these activations were significantly and similarly reduced in both cochlear implant groups, whereas control subjects showed supplementary activations. Compared with non-voice, the voice stimuli induced bilateral activation of the TVA along the superior temporal sulcus (STS) in both the control and the Good groups. In contrast, these activations were not detected in the Poor group, which showed only left unilateral middle STS activation. Conclusion: These results suggest that PET is an adequate method to explore cochlear implant benefits and that this benefit could be linked to the activation of the TVA. (authors)

  20. Cochlear implant benefits in deafness rehabilitation: PET study of temporal voice Activations

    International Nuclear Information System (INIS)

    Coez, A.; Zilbovicius, M.; Zilbovicius, M.; Syrota, A.; Samson, Y.; Bizaguet, E.; Coez, A.; Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O.; Ambert-Dahan, E.; Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O.; Samson, Y.; Samson, Y.; Sterkers, O.

    2008-01-01

    Cochlear implants may improve the medical and social prognosis of profound deafness. Nevertheless, some patients have experienced poor results without any clear explanations. One correlate may be an alteration in cortical voice processing. To test this hypothesis, we studied the activation of human temporal voice areas (TVA) using a well-standardized PET paradigm adapted from previous functional MRI (fMRI) studies. Methods: A PET H 2 15 O activation study was performed on 3 groups of adult volunteers: normal-hearing control subjects (n 6) and cochlear-implanted post-lingually deaf patients with ≥2 y of cochlear implant experience, with intelligibility scores in the 'Lafon monosyllabic task' ≥80% (Good group; n 6) or ≤20% (Poor group; n 6). Relative cerebral blood flow was measured in 3 conditions: rest, passive listening to human voice, and non-voice stimuli. Results: Compared with silence, the activations induced by non-voice stimuli were bilaterally located in the superior temporal regions in all groups. However these activations were significantly and similarly reduced in both cochlear implant groups, whereas control subjects showed supplementary activations. Compared with non-voice, the voice stimuli induced bilateral activation of the TVA along the superior temporal sulcus (STS) in both the control and the Good groups. In contrast, these activations were not detected in the Poor group, which showed only left unilateral middle STS activation. Conclusion: These results suggest that PET is an adequate method to explore cochlear implant benefits and that this benefit could be linked to the activation of the TVA. (authors)

  1. Study on folate receptor PET imaging agent 18F-flurophenethyl folate

    International Nuclear Information System (INIS)

    Guo Congying; Zhu Jianhua; Qian Jun; Yang Yang; Shen Haixing; Zhang Zhengwei

    2009-01-01

    This work is aimed at synthesizing an 18 F-labelled folate derivative that can be used as folate-receptor induced tumor PET imaging agent. Under the optimal reaction and testing specification formulated during the cold-labeling experiments, 18 F labeling of folic acid was achieved in three steps of 18 F pre-labeling,bromination and esterification. The receptor binding property of the newly-synthesized folate radio-derivative was studied through β-lactoglobulin binding test. Tumor-bearing nude mice injected with the new compound were used to study whether the derivative can accumulate within tumor issue. Preliminary studies in vitro and in vivo showed that this new PET agent still possessed receptor binding qualities of folic acid. 18 F-flurophenethyl folate remained good affinity and specificity with β-lactoglobulin. Accumulation of activities in tumor tissues was found in tumor-bearing nude mice. A new folate receptor ligand: 18 F-flurophenethyl folate was synthesized,with high yield and good stability. Since the pre-labeling method was used, the fluorine labeling was not directly imposed upon folic acid.In this way, the structure destruction, which happens in high temperature reaction of folic acid, can be avoided. The synthesized folate derivative remained the binding structural quality of folic acid and could bind with the folate-binding protein: β-lactoglobulin. Through the folate receptors located on tumor tissues, 18 F-flurophenethyl folate accumulated in the tumor tissue, exhibiting its potential as a tumor PET imaging agent. (authors)

  2. Prostate cancer: a comparative study of {sup 11}C-choline PET and MR imaging combined with proton MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Takako; Lee, Jin; Takahashi, Nobukazu; Oka, Takashi; Shizukuishi, Kazuya; Inoue, Tomio [Yokohama City University School of Medicine, Department of Radiology, Yokohama (Japan); Uemura, Hiroji; Kubota, Yoshinobu [Yokohama City University School of Medicine, Department of Urology, Kanagawa (Japan); Sasaki, Takeshi [Yokohama City University School of Medicine, Department of Pathology, Kanagawa (Japan); Endou, Hisashi [Yokohama City University School of Medicine, Department of Pharmacy, Kanagawa (Japan)

    2005-07-01

    Prostate cancer is difficult to visualise in its early stages using current imaging technology. The present study aimed to clarify the utility of {sup 11}C-choline PET for localising and evaluating cancer lesions in patients with prostate cancer by conducting a prospective comparison with magnetic resonance (MR) imaging combined with proton MR spectroscopy. PET and MR imaging combined with proton MR spectroscopy were performed in 20 patients with prostate cancer. Correlations among the metabolite ratio of choline + creatine to citrate (Cho+Cr/Ci) on MR spectroscopy, serum PSA and maximum standardised uptake value (SUV{sub max}) of {sup 11}C-choline were assessed. The location of the primary lesion was assessed by the site of SUV{sub max} and the laterality of the highest Cho+Cr/Ci ratio and confirmed by examination of surgical pathology specimens (n=16). PET exhibited a diagnostic sensitivity of 100% (20/20) for primary lesions, while the sensitivities of MR imaging and MR spectroscopy were 60% (12/20) and 65% (13/20), respectively. Weak linear correlations were observed between SUV{sub max} and serum PSA (r=0.52, p<0.05), and between SUV{sub max} and Cho+Cr/Ci ratio (r=0.49, p<0.05). Regarding the localisation of main primary lesions, PET results agreed with pathological findings in 13 patients (81%) ({kappa}=0.59), while MR spectroscopy results were in accordance with pathological findings in eight patients (50%) ({kappa}=0.11). This preliminary study suggests that {sup 11}C-choline PET may provide more accurate information regarding the localisation of main primary prostate cancer lesions than MR imaging/MR spectroscopy. A further clinical study of {sup 11}C-choline PET in a large number of patients suspected of prostate cancer will be necessary to determine the clinical utility of {sup 11}C-choline PET in patients who clinically require biopsy. (orig.)

  3. Children, parents, and pets exercising together (CPET randomised controlled trial: study rationale, design, and methods

    Directory of Open Access Journals (Sweden)

    Yam Philippa S

    2012-03-01

    Full Text Available Abstract Background Objectively measured physical activity is low in British children, and declines as childhood progresses. Observational studies suggest that dog-walking might be a useful approach to physical activity promotion in children and adults, but there are no published public health interventions based on dog-walking with children. The Children, Parents, and Pets Exercising Together Study aims to develop and evaluate a theory driven, generalisable, family-based, dog walking intervention for 9-11 year olds. Methods/design The Children, Parents, and Pets Exercising Together Study is an exploratory, assessor-blinded, randomised controlled trial as defined in the UK MRC Framework on the development and evaluation of complex interventions in public health. The trial will follow CONSORT guidance. Approximately 40 dog-owning families will be allocated randomly in a ratio of 1.5:1 to receive a simple behavioural intervention lasting for 10 weeks or to a 'waiting list' control group. The primary outcome is change in objectively measured child physical activity using Actigraph accelerometry. Secondary outcomes in the child, included in part to shape a future more definitive randomised controlled trial, are: total time spent sedentary and patterning of sedentary behaviour (Actigraph accelerometry; body composition and bone health from dual energy x-ray absorptiometry; body weight, height and BMI; and finally, health-related quality of life using the PedsQL. Secondary outcomes in parents and dogs are: changes in body weight; changes in Actigraph accelerometry measured physical activity and sedentary behaviour. Process evaluation will consist of assessment of simultaneous child, parent, and dog accelerometry data and brief interviews with participating families. Discussion The Children, Parents, and Pets Exercising Together trial should be the first randomised controlled study to establish and evaluate an intervention aimed at dog-based physical

  4. Study of DOI resolution and imaging resolution of a PET device

    International Nuclear Information System (INIS)

    Saha, Lipika; Saitoh, Kazumi; Kobayashi, Shigeharu

    2004-01-01

    As a recent trend of DOI measurement for the PET, a simple method of utilizing the light attenuation properties of scintillation materials has been paid attention. We have studied the DOI resolutions for less expensive materials as BGO in both the bench test and the simulation by GEANT4.0. By comparison with both the results, we have recognized the importance of removing the multiple Compton absorption events to obtain the better DOI information. The simulation results for the imaging resolution suggested that its deterioration attributes to the parallax error as well as the systematic displacement inherent in the present method of 3D-reconstruction

  5. Children, parents, and pets exercising together (CPET) randomised controlled trial: study rationale, design, and methods.

    Science.gov (United States)

    Yam, Philippa S; Morrison, Ryan; Penpraze, Viki; Westgarth, Carri; Ward, Dianne S; Mutrie, Nanette; Hutchison, Pippa; Young, David; Reilly, John J

    2012-03-19

    Objectively measured physical activity is low in British children, and declines as childhood progresses. Observational studies suggest that dog-walking might be a useful approach to physical activity promotion in children and adults, but there are no published public health interventions based on dog-walking with children. The Children, Parents, and Pets Exercising Together Study aims to develop and evaluate a theory driven, generalisable, family-based, dog walking intervention for 9-11 year olds. The Children, Parents, and Pets Exercising Together Study is an exploratory, assessor-blinded, randomised controlled trial as defined in the UK MRC Framework on the development and evaluation of complex interventions in public health. The trial will follow CONSORT guidance. Approximately 40 dog-owning families will be allocated randomly in a ratio of 1.5:1 to receive a simple behavioural intervention lasting for 10 weeks or to a 'waiting list' control group. The primary outcome is change in objectively measured child physical activity using Actigraph accelerometry. Secondary outcomes in the child, included in part to shape a future more definitive randomised controlled trial, are: total time spent sedentary and patterning of sedentary behaviour (Actigraph accelerometry); body composition and bone health from dual energy x-ray absorptiometry; body weight, height and BMI; and finally, health-related quality of life using the PedsQL. Secondary outcomes in parents and dogs are: changes in body weight; changes in Actigraph accelerometry measured physical activity and sedentary behaviour. Process evaluation will consist of assessment of simultaneous child, parent, and dog accelerometry data and brief interviews with participating families. The Children, Parents, and Pets Exercising Together trial should be the first randomised controlled study to establish and evaluate an intervention aimed at dog-based physical activity promotion in families. It should advance our

  6. Data-driven intensity normalization of PET group comparison studies is superior to global mean normalization

    DEFF Research Database (Denmark)

    Borghammer, Per; Aanerud, Joel; Gjedde, Albert

    2009-01-01

    BACKGROUND: Global mean (GM) normalization is one of the most commonly used methods of normalization in PET and SPECT group comparison studies of neurodegenerative disorders. It requires that no between-group GM difference is present, which may be strongly violated in neurodegenerative disorders....... Importantly, such GM differences often elude detection due to the large intrinsic variance in absolute values of cerebral blood flow or glucose consumption. Alternative methods of normalization are needed for this type of data. MATERIALS AND METHODS: Two types of simulation were performed using CBF images...

  7. Alteration of default mode network in high school football athletes due to repetitive subconcussive mild traumatic brain injury: a resting-state functional magnetic resonance imaging study.

    Science.gov (United States)

    Abbas, Kausar; Shenk, Trey E; Poole, Victoria N; Breedlove, Evan L; Leverenz, Larry J; Nauman, Eric A; Talavage, Thomas M; Robinson, Meghan E

    2015-03-01

    Long-term neurological damage as a result of head trauma while playing sports is a major concern for football athletes today. Repetitive concussions have been linked to many neurological disorders. Recently, it has been reported that repetitive subconcussive events can be a significant source of accrued damage. Since football athletes can experience hundreds of subconcussive hits during a single season, it is of utmost importance to understand their effect on brain health in the short and long term. In this study, resting-state functional magnetic resonance imaging (rs-fMRI) was used to study changes in the default mode network (DMN) after repetitive subconcussive mild traumatic brain injury. Twenty-two high school American football athletes, clinically asymptomatic, were scanned using the rs-fMRI for a single season. Baseline scans were acquired before the start of the season, and follow-up scans were obtained during and after the season to track the potential changes in the DMN as a result of experienced trauma. Ten noncollision-sport athletes were scanned over two sessions as controls. Overall, football athletes had significantly different functional connectivity measures than controls for most of the year. The presence of this deviation of football athletes from their healthy peers even before the start of the season suggests a neurological change that has accumulated over the years of playing the sport. Football athletes also demonstrate short-term changes relative to their own baseline at the start of the season. Football athletes exhibited hyperconnectivity in the DMN compared to controls for most of the sessions, which indicates that, despite the absence of symptoms typically associated with concussion, the repetitive trauma accrued produced long-term brain changes compared to their healthy peers.

  8. Lung PET scan

    Science.gov (United States)

    ... Chest PET scan; Lung positron emission tomography; PET - chest; PET - lung; PET - tumor imaging; ... Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging . 6th ed. Philadelphia, ...

  9. A prospective multi-centre study of the value of FDG-PET as part of a structured diagnostic protocol in patients with fever of unknown origin

    International Nuclear Information System (INIS)

    Bleeker-Rovers, Chantal P.; Vos, Fidel J.; Meer, Jos W.M. van der; Mudde, Aart H.; Dofferhoff, Anton S.M.; Geus-Oei, Lioe-Fee de; Rijnders, Anton J.; Krabbe, Paul F.M.; Corstens, Frans H.M.; Oyen, Wim J.G.

    2007-01-01

    Since 18 F-fluorodeoxyglucose (FDG) accumulates in neoplastic cells and in activated inflammatory cells, positron emission tomography (PET) with FDG could be valuable in diagnosing patients with fever of unknown origin (FUO). The aim of this study was to validate the use of FDG-PET as part of a structured diagnostic protocol in the general patient population with FUO. From December 2003 to July 2005, 70 patients with FUO were recruited from one university hospital (n=38) and five community hospitals (n=32). A structured diagnostic protocol including FDG-PET was used. A dedicated, full-ring PET scanner was used for data acquisition. FDG-PET scans were interpreted by two staff members of the department of nuclear medicine without further clinical information. The final clinical diagnosis was used for comparison with the FDG-PET results. Of all scans, 33% were clinically helpful. The contribution of FDG-PET to the final diagnosis did not differ significantly between patients diagnosed in the university hospital and patients diagnosed in the community hospitals. FDG-PET contributed significantly more often to the final diagnosis in patients with continuous fever than in patients with periodic fever. FDG-PET was not helpful in any of the patients with normal erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). FDG-PET is a valuable imaging technique as part of a diagnostic protocol in the general patient population with FUO and a raised ESR or CRP. (orig.)

  10. Simulation study of LYSO crystal pixels for In-Beam TOF-PET prototype

    International Nuclear Information System (INIS)

    Chen Ze; Hu Zhengguo; Chen Jinda; Zhang Xiuling

    2014-01-01

    In-beam TOF-PET is currently the only feasible method implemented for in-situ and noninvasive monitoring of the precision of the treatment in highly conformal ion radiotherapy. It ensures the safety of patient and accurate implementation of treatment plan. Therefore, we intent to carry out the development of In-beam TOF-PET prototype, which is made of LYSO crystal, for ion radiotherapy. LYSO crystal has perfect properties such as high light yield, fast decay time, good energy and time resolution, which makes it a good candidate. In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection and energy resolution is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte Carlo simulations play an important role in guiding research in detector designs and popular software such as Gate now include models of light transport in scintillators. This study uses Gate software to investigate the influence of crystal length and wrapping materials to the light collection. Accurate physical modeling of scintillation detection process, from scintillation light generation through detection, is devised and performed for varying detector attributes, such as the crystal pixel length, light yield, decay time, attenuation length and surface treatment. The dependence of light output and energy resolution is studied and compared with experiment results. The results show that LYSO pixel with length of 5 mm has better light yield and energy resolution, meanwhile prove that it is possible to accurately simulate the light output using Gate. (authors)

  11. Myocardial glucose metabolism in patients with hypertrophic cardiomyopathy. Assessment by F-18-FDG PET study

    International Nuclear Information System (INIS)

    Uehara, Toshiisa; Ishida, Yoshio; Hayashida, Kohei

    1998-01-01

    In an investigation of myocardial metabolic abnormalities in hypertrophic myocardium, the myocardial glucose metabolism was evaluated with F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) in 32 patients with hypertrophic cardiomyopathy, and the results were compared with those in 9 patients with hypertensive heart disease. F-18-FDG PET study was performed in the fasting and glucose-loading states. The myocardial regional %dose uptake was calculated quantitatively. The average regional %dose uptake in the fasting state in the patients with asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy was significantly higher than that in the patients with hypertensive heart disease (0.75±0.34%, 0.65±0.25%, and 0.43±0.22%/100 g myocardium, respectively). In contrast, the average %dose uptake in the glucose-loading state in the patients with asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy was not significantly different from that in patients with hypertensive heart disease (1.17±0.49%, 0.80±0.44% and 0.99±0.45%, respectively). The patients with apical hypertrophy had also low %dose uptake in the fasting state (0.38±0.21%) as in the hypertensive heart disease patients, so that the characteristics of asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy are considered to be high FDG uptake throughout the myocardium in the fasting state. Patients with apical hypertrophy are considered to belong to other disease categories metabolically. F-18-FDG PET study is useful in the evaluation of the pathophysiologic diagnosis of patients with hypertrophic cardiomyopathy. (author)

  12. Characterization of bromine-76-labelled 5-bromo-6-nitroquipazine for PET studies of the serotonin transporter

    Energy Technology Data Exchange (ETDEWEB)

    Lundkvist, Camilla E-mail: Lundkvis@shfj.cea.fr; Loc' h, Christian; Halldin, Christer; Bottlaender, Michel; Ottaviani, Michele; Coulon, Christine; Fuseau, Chantal; Mathis, Chester; Farde, Lars; Maziere, Bernard

    1999-07-01

    The development of suitable radioligands for brain imaging of the serotonin transporter is of great importance for the study of depression and other affective disorders. The potent and selective serotonin transporter ligand, 5-iodo-6-nitro-2-piperazinylquinoline, has been labelled with iodine-123 and used as a radioligand for single photon emission computerized tomography. To evaluate the potential of the bromine-76-labelled analogue, 5-bromo-6-nitroquipazine, as a radioligand for positron emission tomography (PET), its brain distribution and binding characteristics were examined in rats. In vivo brain distribution and ex vivo autoradiography demonstrated that [{sup 76}Br]5-bromo-6-nitroquipazine enters the brain rapidly. The regional brain distribution of [{sup 76}Br]5-bromo-6-nitroquipazine was consistent with the known distribution of serotonin transporters in the midbrain, pons, thalamus, striatum, and neocortex. Specific binding was inhibited by the selective serotonin reuptake inhibitor citalopram. The peripheral metabolism in plasma was rapid, but more than 90% of the radioactivity in brain represented unchanged radioligand 2 h postinjection (p.i.). A preliminary PET study was also performed in a baboon. Following the intravenous injection of [{sup 76}Br]5-bromo-6-nitroquipazine in a baboon, there was a conspicuous accumulation of radioactivity in thalamus, striatum, and pons. The radioactivity in these brain regions was 1.5 times higher than in the cerebellum at 3 h and 2.5-4 times higher at 24 h. A rapid metabolism of the radioligand in plasma was observed (38% unchanged after 5 min). The results indicate that [{sup 76}Br]5-bromo-6-nitroquipazine has potential for PET imaging of the serotonin transporter.

  13. Study of an image-derived SUV and a modified SUV using mouse FDG-PET

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Xiujuan, E-mail: zhengxj@eie.polyu.edu.h [Department of Electronic Information Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Yu, Chin-Lung; Sha Wei; Radu, Caius; Huang, Sung-Cheng [Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, University of California Los Angeles, CA (United States); Feng Dagan [Department of Electronic Information Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); School of Information Technologies, the University of Sydney, Sydney (Australia)

    2011-04-15

    Introduction: Standard uptake value (SUV) is calculated without consideration of the differences in plasma 2-deoxy-2-[18F]fluoro-D-glucose (FDG) clearance. Its variability can be affected by changes of the amount of excreted FDG by renal function. Moreover, the estimation of SUV is quite sensitive to errors in the measurements of body weight and injected dose. This study aims to develop an image-based method to obtain an image-derived SUV (iSUV) and a modified SUV (mSUV) to overcome these problems. Methods: Thirty-one tumor-planted SCID mice were scanned in micro-positron emission tomography (PET) at {approx}60 min post FDG injection and then scanned in micro-computed tomographic (CT). Using image-based method, the body weight and injected dose were derived from the microPET/CT images to calculate iSUV. The volumes and the total activities of FDG within the bladder and the whole-body were also obtained to calculate mSUV. For the selected targets, the iSUVs and mSUVs were compared against their corresponding SUVs. Results: Compared with SUV factor (injected dose/body weight), iSUV factor had an average percentage error of -0.7%. The linear regressions between SUV and iSUV had a slope of 0.99 with correlation coefficient of 0.95. Compared with SUV and iSUV, coefficient of variation of mSUV decreased while the tumor-to-background separation of mSUV increased. Conclusions: Using this image-based method, the iSUV can replace SUV when the actual measurements were missing or unreliable. The mSUV can reduce the inter-subject variability and enhance the tumor-to-background separation in mouse FDG-PET studies.

  14. Study of an image-derived SUV and a modified SUV using mouse FDG-PET

    International Nuclear Information System (INIS)

    Zheng Xiujuan; Yu, Chin-Lung; Sha Wei; Radu, Caius; Huang, Sung-Cheng; Feng Dagan

    2011-01-01

    Introduction: Standard uptake value (SUV) is calculated without consideration of the differences in plasma 2-deoxy-2-[18F]fluoro-D-glucose (FDG) clearance. Its variability can be affected by changes of the amount of excreted FDG by renal function. Moreover, the estimation of SUV is quite sensitive to errors in the measurements of body weight and injected dose. This study aims to develop an image-based method to obtain an image-derived SUV (iSUV) and a modified SUV (mSUV) to overcome these problems. Methods: Thirty-one tumor-planted SCID mice were scanned in micro-positron emission tomography (PET) at ∼60 min post FDG injection and then scanned in micro-computed tomographic (CT). Using image-based method, the body weight and injected dose were derived from the microPET/CT images to calculate iSUV. The volumes and the total activities of FDG within the bladder and the whole-body were also obtained to calculate mSUV. For the selected targets, the iSUVs and mSUVs were compared against their corresponding SUVs. Results: Compared with SUV factor (injected dose/body weight), iSUV factor had an average percentage error of -0.7%. The linear regressions between SUV and iSUV had a slope of 0.99 with correlation coefficient of 0.95. Compared with SUV and iSUV, coefficient of variation of mSUV decreased while the tumor-to-background separation of mSUV increased. Conclusions: Using this image-based method, the iSUV can replace SUV when the actual measurements were missing or unreliable. The mSUV can reduce the inter-subject variability and enhance the tumor-to-background separation in mouse FDG-PET studies.

  15. Smoking-induced dopamine release studied with [{sup 11}C]Raclopride PET

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu Kyeong; Cho, Sang Soo [Seoul National University College of Medicine, Seoul (Korea, Republic of); Lee, Do Hoon [Center for Clinical Services, National Cancer Certer, Goyang (Korea, Republic of)] (and others)

    2005-10-15

    It has been postulated that dopamine release in the striatum underlies the reinforcing properties of nicotine. Substantial evidence in the animal studies demonstrates that nicotine interacts with dopaminergic neuron and regulates the activation of the dopaminergic system. The aim of this study was to visualize the dopamine release by smoking in human brain using PET scan with [{sup 11}C]raclopride. Five male non-smokers or ex-smokers with an abstinence period longer than 1 year (mean age of 24.4 {+-} 1.7 years) were enrolled in this study. [{sup 1C}]raclopride, a dopamine D2 receptor radioligand, was administrated with bolus-plus-constant infusion. Dynamic PET was performed during 120 minutes (3 x 20s, 2 x 60s, 2 x 120s, 1 x 180s and 22 x 300s). Following the 50 minute-scanning, subjects smoked a cigarette containing 1 mg of nicotine while in the scanner. Blood samples for the measurement of plasma nicotine level were collected at 0, 5, 10, 15, 20, 25, 30, 45, 60, and 90 minute after smoking. Regions for striatal structures were drawn on the coronal summed PET images guided with co-registered MRI. Binding potential, calculated as (striatal-cerebellar)/cerebellar activity, was measured under equilibrium condition at baseline and smoking session. The mean decrease in binding potential of [{sup 1C}]raclopride between the baseline and smoking in caudate head, anterior putamen and ventral striatum was 4.7%, 4.0% and 7.8%, respectively. This indicated the striatal dopamine release by smoking. Of these, the reduction in binding potential in the ventral striatum was significantly correlated with the cumulated plasma level of the nicotine (Spearman's rho=0.9, {rho} =0.4). These data demonstrate that in vivo imaging with [{sup 11}C]raclopride PET could measure nicotine-induced dopamine release in the human brain, which has a significant positive correlation with the amount of nicotine administered by smoking.

  16. Improvement of semi-quantitative small-animal PET data with recovery coefficients: a phantom and rat study.

    Science.gov (United States)

    Aide, Nicolas; Louis, Marie-Hélène; Dutoit, Soizic; Labiche, Alexandre; Lemoisson, Edwige; Briand, Mélanie; Nataf, Valérie; Poulain, Laurent; Gauduchon, Pascal; Talbot, Jean-Noël; Montravers, Françoise

    2007-10-01

    To evaluate the accuracy of semi-quantitative small-animal PET data, uncorrected for attenuation, and then of the same semi-quantitative data corrected by means of recovery coefficients (RCs) based on phantom studies. A phantom containing six fillable spheres (diameter range: 4.4-14 mm) was filled with an 18F-FDG solution (spheres/background activity=10.1, 5.1 and 2.5). RCs, defined as measured activity/expected activity, were calculated. Nude rats harbouring tumours (n=50) were imaged after injection of 18F-FDG and sacrificed. The standardized uptake value (SUV) in tumours was determined with small-animal PET and compared to ex-vivo counting (ex-vivo SUV). Small-animal PET SUVs were corrected with RCs based on the greatest tumour diameter. Tumour proliferation was assessed with cyclin A immunostaining and correlated to the SUV. RCs ranged from 0.33 for the smallest sphere to 0.72 for the largest. A sigmoidal correlation was found between RCs and sphere diameters (r(2)=0.99). Small-animal PET SUVs were well correlated with ex-vivo SUVs (y=0.48x-0.2; r(2)=0.71) and the use of RCs based on the greatest tumour diameter significantly improved regression (y=0.84x-0.81; r(2)=0.77), except for tumours with important necrosis. Similar results were obtained without sacrificing animals, by using PET images to estimate tumour dimensions. RC-based corrections improved correlation between small-animal PET SUVs and tumour proliferation (uncorrected data: Rho=0.79; corrected data: Rho=0.83). Recovery correction significantly improves both accuracy of small-animal PET semi-quantitative data in rat studies and their correlation with tumour proliferation, except for largely necrotic tumours.

  17. Integrated boost IMRT with FET-PET-adapted local dose escalation in glioblastomas. Results of a prospective phase II study

    International Nuclear Information System (INIS)

    Piroth, M.D.; Pinkawa, M.; Holy, R.; Forschungszentrum Juelich GmbH

    2012-01-01

    Dose escalations above 60 Gy based on MRI have not led to prognostic benefits in glioblastoma patients yet. With positron emission tomography (PET) using [ 18 F]fluorethyl-L-tyrosine (FET), tumor coverage can be optimized with the option of regional dose escalation in the area of viable tumor tissue. In a prospective phase II study (January 2008 to December 2009), 22 patients (median age 55 years) received radiochemotherapy after surgery. The radiotherapy was performed as an MRI and FET-PET-based integrated-boost intensity-modulated radiotherapy (IMRT). The prescribed dose was 72 and 60 Gy (single dose 2.4 and 2.0 Gy, respectively) for the FET-PET- and MR-based PTV-FET (72 Gy) and PTV-MR (60 Gy) . FET-PET and MRI were performed routinely for follow-up. Quality of life and cognitive aspects were recorded by the EORTC-QLQ-C30/QLQ Brain20 and Mini-Mental Status Examination (MMSE), while the therapy-related toxicity was recorded using the CTC3.0 and RTOG scores. Median overall survival (OS) and disease-free survival (DFS) were 14.8 and 7.8 months, respectively. All local relapses were detected at least partly within the 95% dose volume of PTV-MR (60 Gy) . No relevant radiotherapy-related side effects were observed (excepted alopecia). In 2 patients, a pseudoprogression was observed in the MRI. Tumor progression could be excluded by FET-PET and was confirmed in further MRI and FET-PET imaging. No significant changes were observed in MMSE scores and in the EORTC QLQ-C30/QLQ-Brain20 questionnaires. Our dose escalation concept with a total dose of 72 Gy, based on FET-PET, did not lead to a survival benefit. Acute and late toxicity were not increased, compared with historical controls and published dose-escalation studies. (orig.)

  18. Phantom study on three-dimensional target volume delineation by PET/CT-based auto-contouring

    International Nuclear Information System (INIS)

    Zhang, Tiejiao; Sakaguchi, Yuichi; Mitsumoto, Katsuhiko; Mitsumoto, Tatsuya; Sasaki, Masayuki; Tachiya, Yosuke; Ohya, Nobuyoshi

    2010-01-01

    The aim of this study was to determine an appropriate threshold value for delineation of the target volume in positron emission tomography (PET)/CT and to investigate whether we could delineate a target volume by phantom studies. A phantom consisted of six spheres (φ10-37 mm) filled with 18 F solution. Data acquisition was performed PET/CT in non-motion and motion status with high 18 F solution and in non-motion status with low 18 F solution. In non-motion phantom experiments, we determined two types of threshold value, an absolute SUV (T SUV ) and a percentage of the maximum SUV (T % ). Delineation using threshold values was applied for all spheres and for selected large spheres (a diameter of 22 mm or larger). In motion phantom experiments, data acquisition was performed in a static mode (sPET) and a gated mode (gPET). CT scanning was performed with helical CT (HCT) and 4-dimentional CT (4DCT). The appropriate threshold values were aT % =27% and aT SUV =2.4 for all spheres, and sT % =30% and sT SUV =4.3 for selected spheres. For all spheres in sPET/HCT in motion, the delineated volumes were 84%-129% by the aT % and 34%-127% by the aT SUV . In gPET/4DCT in motion, the delineated volumes were 94-103% by the aT % and 51-131% by the aT SUV . For low radioactivity spheres, the delineated volumes were all underestimated. A threshold value of T % =27% was proposed for auto-contouring of lung tumors. Our results also suggested that the respiratory gated data acquisition should be performed in both PET and CT for target volume delineation. (author)

  19. Integrated boost IMRT with FET-PET-adapted local dose escalation in glioblastomas. Results of a prospective phase II study

    Energy Technology Data Exchange (ETDEWEB)

    Piroth, M.D.; Pinkawa, M.; Holy, R. [RWTH Aachen University Hospital (Germany). Dept. of Radiation Oncology; Forschungszentrum Juelich GmbH (DE). Juelich-Aachen Research Alliance (JARA) - Section JARA-Brain] (and others)

    2012-04-15

    Dose escalations above 60 Gy based on MRI have not led to prognostic benefits in glioblastoma patients yet. With positron emission tomography (PET) using [{sup 18}F]fluorethyl-L-tyrosine (FET), tumor coverage can be optimized with the option of regional dose escalation in the area of viable tumor tissue. In a prospective phase II study (January 2008 to December 2009), 22 patients (median age 55 years) received radiochemotherapy after surgery. The radiotherapy was performed as an MRI and FET-PET-based integrated-boost intensity-modulated radiotherapy (IMRT). The prescribed dose was 72 and 60 Gy (single dose 2.4 and 2.0 Gy, respectively) for the FET-PET- and MR-based PTV-FET{sub (72 Gy)} and PTV-MR{sub (60 Gy)}. FET-PET and MRI were performed routinely for follow-up. Quality of life and cognitive aspects were recorded by the EORTC-QLQ-C30/QLQ Brain20 and Mini-Mental Status Examination (MMSE), while the therapy-related toxicity was recorded using the CTC3.0 and RTOG scores. Median overall survival (OS) and disease-free survival (DFS) were 14.8 and 7.8 months, respectively. All local relapses were detected at least partly within the 95% dose volume of PTV-MR{sub (60 Gy)}. No relevant radiotherapy-related side effects were observed (excepted alopecia). In 2 patients, a pseudoprogression was observed in the MRI. Tumor progression could be excluded by FET-PET and was confirmed in further MRI and FET-PET imaging. No significant changes were observed in MMSE scores and in the EORTC QLQ-C30/QLQ-Brain20 questionnaires. Our dose escalation concept with a total dose of 72 Gy, based on FET-PET, did not lead to a survival benefit. Acute and late toxicity were not increased, compared with historical controls and published dose-escalation studies. (orig.)

  20. Repetition of self-harm and suicide following self-harm in children and adolescents: findings from the Multicentre Study of Self-harm in England.

    Science.gov (United States)

    Hawton, Keith; Bergen, Helen; Kapur, Navneet; Cooper, Jayne; Steeg, Sarah; Ness, Jennifer; Waters, Keith

    2012-12-01

    Self-harm (intentional self-poisoning and self-injury) in children and adolescents is often repeated and is associated with increased risk of future suicide. We have investigated factors associated with these outcomes. We used data collected in the Multicentre Study of Self-harm in England on all self-harm hospital presentations by individuals aged 10-18 years between 2000 and 2007, and national death information on these individuals to the end of 2010. Cox hazard proportional models were used to identify independent and multivariable predictors of repetition of self-harm and of suicide. Repetition of self-harm occurred in 27.3% of individuals (N = 3920) who presented between 2000 and 2005 and were followed up until 2007. Multivariate analysis showed that repetition was associated with age, self-cutting, and previous self-harm and psychiatric treatment. Of 51 deaths in individuals who presented between 2000 and 2007 and were followed up to 2010 (N = 5133) half (49.0%) were suicides. The method used was usually different to that used for self-harm. Multivariate analysis showed that suicide was associated with male gender [Hazard ratio (HR) = 2.4, 95% CI 1.2-4.8], self-cutting (HR = 2.1, 95% CI 1.1-3.7) and prior psychiatric treatment at initial presentation (HR = 4.2, 95% CI 1.7-10.5). It was also associated with self-cutting and history of psychiatric treatment at the last episode before death, and history of previous self harm. Self-cutting as a method of self-harm in children and adolescents conveys greater risk of suicide (and repetition) than self-poisoning although different methods are usually used for suicide. The findings underline the need for psychosocial assessment in all cases. © 2012 The Authors. Journal of Child Psychology and Psychiatry © 2012 Association for Child and Adolescent Mental Health.

  1. Mild traumatic brain injury results in depressed cerebral glucose uptake: An (18)FDG PET study.

    Science.gov (United States)

    Selwyn, Reed; Hockenbury, Nicole; Jaiswal, Shalini; Mathur, Sanjeev; Armstrong, Regina C; Byrnes, Kimberly R

    2013-12-01

    Moderate to severe traumatic brain injury (TBI) in humans and rats induces measurable metabolic changes, including a sustained depression in cerebral glucose uptake. However, the effect of a mild TBI on brain glucose uptake is unclear, particularly in rodent models. This study aimed to determine the glucose uptake pattern in the brain after a mild lateral fluid percussion (LFP) TBI. Briefly, adult male rats were subjected to a mild LFP and positron emission tomography (PET) imaging with (18)F-fluorodeoxyglucose ((18)FDG), which was performed prior to injury and at 3 and 24 h and 5, 9, and 16 days post-injury. Locomotor function was assessed prior to injury and at 1, 3, 7, 14, and 21 days after injury using modified beam walk tasks to confirm injury severity. Histology was performed at either 10 or 21 days post-injury. Analysis of function revealed a transient impairment in locomotor ability, which corresponds to a mild TBI. Using reference region normalization, PET imaging revealed that mild LFP-induced TBI depresses glucose uptake in both the ipsilateral and contralateral hemispheres in comparison with sham-injured and naïve controls from 3 h to 5 days post-injury. Further, areas of depressed glucose uptake were associated with regions of glial activation and axonal damage, but no measurable change in neuronal loss or gross tissue damage was observed. In conclusion, we show that mild TBI, which is characterized by transient impairments in function, axonal damage, and glial activation, results in an observable depression in overall brain glucose uptake using (18)FDG-PET.

  2. Regional cerebral glucose metabolism in frontotemporal dementia: a study with FDG PET

    Energy Technology Data Exchange (ETDEWEB)

    Cho, S. S.; Jeong, J.; Kang, S. J.; Na, D. L.; Choe, Y. S.; Lee, K. H.; Choi, Y.; Kim, B. T.; Kim, S. E. [Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2002-07-01

    Frontotemporal dementia (FTD) is a common cause of presenile dementia. We investigated the regional cerebral glucose metabolic impairments in patients with FTD using FDG PET. We analysed the regional metabolic patterns on FDG PET images obtained from 30 patients with FTD and age- and sex-matched 15 patients with Alzheimers disease (AD) and 11 healthy subjects using SPM99. We also compared the inter-hemispheric metabolic asymmetry among the three groups by counting the total metabolic activity of each hemisphere and computing asymmetry index (AL) between hemispheres. The hypometabolic brain regions in FTD patients compared with healthy controls were as follows: superior middle and medial frontal lobules, superior and middle temporal lobules, anterior and posterior cingulate gyri, uncus, insula, lateral globus pallidus and thalamus. The regions with decreased metabolism in FTD patients compared with AD patients were as follows: superior, inferior and medial frontal lobules, anterior cingulate gyrus, and caudate nucleus. Twenty-five (83%) out of the 30 FTD patients had AI values that was beyond the 95% confidence interval of the AI values obtained from healthy controls; 10 patients had hypometabolism more severe on the right and 15 patients had the opposite pattern. In comparison, 10 (67%) out of the 15 AD patients had asymmetric metabolism. Our SPM analysis of FDG PET revealed additional areas of decreased metabolism in FTD patients compared with prior studies using the ROI method, involving frontal, temporal, cingulate gyrus, corpus callosum, uncus, insula, and some subcortical areas. The inter-hemispheric metabolic asymmetry was common in FTD patients, which can be another metabolic feature that helps differentiate FTD from AD.

  3. Regional cerebral glucose metabolism in frontotemporal dementia: a study with FDG PET

    International Nuclear Information System (INIS)

    Cho, S. S.; Jeong, J.; Kang, S. J.; Na, D. L.; Choe, Y. S.; Lee, K. H.; Choi, Y.; Kim, B. T.; Kim, S. E.

    2002-01-01

    Frontotemporal dementia (FTD) is a common cause of presenile dementia. We investigated the regional cerebral glucose metabolic impairments in patients with FTD using FDG PET. We analysed the regional metabolic patterns on FDG PET images obtained from 30 patients with FTD and age- and sex-matched 15 patients with Alzheimers disease (AD) and 11 healthy subjects using SPM99. We also compared the inter-hemispheric metabolic asymmetry among the three groups by counting the total metabolic activity of each hemisphere and computing asymmetry index (AL) between hemispheres. The hypometabolic brain regions in FTD patients compared with healthy controls were as follows: superior middle and medial frontal lobules, superior and middle temporal lobules, anterior and posterior cingulate gyri, uncus, insula, lateral globus pallidus and thalamus. The regions with decreased metabolism in FTD patients compared with AD patients were as follows: superior, inferior and medial frontal lobules, anterior cingulate gyrus, and caudate nucleus. Twenty-five (83%) out of the 30 FTD patients had AI values that was beyond the 95% confidence interval of the AI values obtained from healthy controls; 10 patients had hypometabolism more severe on the right and 15 patients had the opposite pattern. In comparison, 10 (67%) out of the 15 AD patients had asymmetric metabolism. Our SPM analysis of FDG PET revealed additional areas of decreased metabolism in FTD patients compared with prior studies using the ROI method, involving frontal, temporal, cingulate gyrus, corpus callosum, uncus, insula, and some subcortical areas. The inter-hemispheric metabolic asymmetry was common in FTD patients, which can be another metabolic feature that helps differentiate FTD from AD

  4. Study and optimization of positioning algorithms for monolithic PET detectors blocks

    International Nuclear Information System (INIS)

    Acilu, P Garcia de; Sarasola, I; Canadas, M; Cuerdo, R; Mendes, P Rato; Romero, L; Willmott, C

    2012-01-01

    We are developing a PET insert for existing MRI equipment to be used in clinical PET/MR studies of the human brain. The proposed scanner is based on annihilation gamma detection with monolithic blocks of cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) coupled to magnetically-compatible avalanche photodiodes (APD) matrices. The light distribution generated on the LYSO:Ce block provides the impinging position of the 511 keV photons by means of a positioning algorithm. Several positioning methods, from the simplest Anger Logic to more sophisticate supervised-learning Neural Networks (NN), can be implemented to extract the incidence position of gammas directly from the APD signals. Finally, an optimal method based on a two-step Feed-Forward Neural Network has been selected. It allows us to reach a resolution at detector level of 2 mm, and acquire images of point sources using a first BrainPET prototype consisting of two monolithic blocks working in coincidence. Neural networks provide a straightforward positioning of the acquired data once they have been trained, however the training process is usually time-consuming. In order to obtain an efficient positioning method for the complete scanner it was necessary to find a training procedure that reduces the data acquisition and processing time without introducing a noticeable degradation of the spatial resolution. A grouping process and posterior selection of the training data have been done regarding the similitude of the light distribution of events which have one common incident coordinate (transversal or longitudinal). By doing this, the amount of training data can be reduced to about 5% of the initial number with a degradation of spatial resolution lower than 10%.

  5. Usage of Recycled Pet

    Directory of Open Access Journals (Sweden)

    A. Ebru Tayyar

    2010-01-01

    Full Text Available The increasing industrialization, urbanization and the technological development have caused to increase depletion of the natural resources and environmental pollution's problem. Especially, for the countries which have not enough space recycling of the waste eliminating waste on regular basis or decreasing the amount and volume of waste have provided the important advantages. There are lots of studies and projects to develop both protect resources and prevent environmental pollution. PET bottles are commonly used in beverage industry and can be reused after physical and chemical recycling processes. Usage areas of recycled PET have been developed rapidly. Although recycled PET is used in plastic industry, composite industry also provides usage alternatives of recycled PET. Textile is a suitable sector for recycling of some plastics made of polymers too. In this study, the recycling technologies and applications of waste PET bottles have been investigated and scientific works in this area have been summarized.

  6. A simulation study of a C-shaped in-beam PET system for dose verification in carbon ion therapy

    International Nuclear Information System (INIS)

    Jung An, Su; Beak, Cheol-Ha; Lee, Kisung; Hyun Chung, Yong

    2013-01-01

    The application of hadrons such as carbon ions is being developed for the treatment of cancer. The effectiveness of such a technique is due to the eligibility of charged particles in delivering most of their energy near the end of the range, called the Bragg peak. However, accurate verification of dose delivery is required since misalignment of the hadron beam can cause serious damage to normal tissue. PET scanners can be utilized to track the carbon beam to the tumor by imaging the trail of the hadron-induced positron emitters in the irradiated volume. In this study, we designed and evaluated (through Monte Carlo simulations) an in-beam PET scanner for monitoring patient dose in carbon beam therapy. A C-shaped PET and a partial-ring PET were designed to avoid interference between the PET detectors and the therapeutic carbon beam delivery. Their performance was compared with that of a full-ring PET scanner. The C-shaped, partial-ring, and full-ring scanners consisted of 14, 12, and 16 detector modules, respectively, with a 30.2 cm inner diameter for brain imaging. Each detector module was composed of a 13×13 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals and four round 25.4 mm diameter PMTs. To estimate the production yield of positron emitters such as 10 C, 11 C, and 15 O, a cylindrical PMMA phantom (diameter, 20 cm; thickness, 20 cm) was irradiated with 170, 290, and 350 AMeV 12 C beams using the GATE code. Phantom images of the three types of scanner were evaluated by comparing the longitudinal profile of the positron emitters, measured along the carbon beam as it passed a simulated positron emitter distribution. The results demonstrated that the development of a C-shaped PET scanner to characterize carbon dose distribution for therapy planning is feasible.

  7. PET/CT-guided treatment planning for paediatric cancer patients: a simulation study of proton and conventional photon therapy

    Science.gov (United States)

    Brodin, N P; Björk-Eriksson, T; Birk Christensen, C; Kiil-Berthelsen, A; Aznar, M C; Hollensen, C; Markova, E; Munck af Rosenschöld, P

    2015-01-01

    Objective: To investigate the impact of including fluorine-18 fludeoxyglucose (18F-FDG) positron emission tomography (PET) scanning in the planning of paediatric radiotherapy (RT). Methods: Target volumes were first delineated without and subsequently re-delineated with access to 18F-FDG PET scan information, on duplicate CT sets. RT plans were generated for three-dimensional conformal photon RT (3DCRT) and intensity-modulated proton therapy (IMPT). The results were evaluated by comparison of target volumes, target dose coverage parameters, normal tissue complication probability (NTCP) and estimated risk of secondary cancer (SC). Results: Considerable deviations between CT- and PET/CT-guided target volumes were seen in 3 out of the 11 patients studied. However, averaging over the whole cohort, CT or PET/CT guidance introduced no significant difference in the shape or size of the target volumes, target dose coverage, irradiated volumes, estimated NTCP or SC risk, neither for IMPT nor 3DCRT. Conclusion: Our results imply that the inclusion of PET/CT scans in the RT planning process could have considerable impact for individual patients. There were no general trends of increasing or decreasing irradiated volumes, suggesting that the long-term morbidity of RT in childhood would on average remain largely unaffected. Advances in knowledge: 18F-FDG PET-based RT planning does not systematically change NTCP or SC risk for paediatric cancer patients compared with CT only. 3 out of 11 patients had a distinct change of target volumes when PET-guided planning was introduced. Dice and mismatch metrics are not sufficient to assess the consequences of target volume differences in the context of RT. PMID:25494657

  8. Experimental study of the performance of a very small repetitive plasma focus device in different working conditions

    Energy Technology Data Exchange (ETDEWEB)

    Goudarzi, S., E-mail: sgoudarzi@aeoi.org.ir; Babaee, H.; Esmaeli, A.; Nasiri, A. [Atomic Energy Organization of Iran, Plasma and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute (Iran, Islamic Republic of)

    2017-01-15

    SORENA-1 is a very small repetitive Mather-type plasma focus device (20 J) that can operate at frequencies up to 1 Hz. This device has been designed and constructed in the Plasma and Nuclear Fusion Research School of the Nuclear Science and Technology Research Institute of Iran. In this article, the structure of SORENA-1 is described and results of experiments with Ar, Ne, and D{sub 2} working gases at several discharge voltages and initial pressures are presented and analyzed.

  9. Pet owners' attitudes and behaviours related to smoking and second-hand smoke: a pilot study.

    Science.gov (United States)

    Milberger, S M; Davis, R M; Holm, A L

    2009-04-01

    Although research indicates that second-hand smoke (SHS) harms both human and animal health, data on the percentage of pet owners who smoke or allow smoking in their homes are not readily available. To investigate pet owners' smoking behaviour and policies on smoking in their homes, and the potential for educational interventions to motivate change in pet owners' smoking behaviour. A web-based survey was used with 3293 adult pet owners. The main outcome measures were smoking behaviour of pet owners and their cohabitants; policies on smoking in pet owners' homes; and impact of information about the dangers of pet exposure to SHS on pet owners' smoking intentions. Of respondents, 21% were current smokers and 27% of participants lived with at least one smoker. Pet owners who smoke reported that information on the dangers of pet exposure to SHS would motivate them to try to quit smoking (28.4%) and ask the people with whom they live to quit smoking (8.7%) or not to smoke indoors (14.2%). Moreover, non-smoking pet owners who live with smokers said that they would ask the people with whom they live to quit (16.4%) or not smoke indoors (24.2%) if given this information. About 40% of current smokers and 24% of non-smokers living with smokers indicated that they would be interested in receiving information on smoking, quitting, or SHS. Educational campaigns informing pet owners of the risks of SHS exposure for pets could motivate some owners to quit smoking. It could also motivate these owners and non-smoking owners who cohabit with smokers make their homes smoke-free.

  10. Dynamic PET simulator via tomographic emission projection for kinetic modeling and parametric image studies

    Energy Technology Data Exchange (ETDEWEB)

    Häggström, Ida, E-mail: haeggsti@mskcc.org [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 and Department of Radiation Sciences, Umeå University, Umeå 90187 (Sweden); Beattie, Bradley J.; Schmidtlein, C. Ross [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States)

    2016-06-15

    Purpose: To develop and evaluate a fast and simple tool called dPETSTEP (Dynamic PET Simulator of Tracers via Emission Projection), for dynamic PET simulations as an alternative to Monte Carlo (MC), useful for educational purposes and evaluation of the effects of the clinical environment, postprocessing choices, etc., on dynamic and parametric images. Methods: The tool was developed in MATLAB using both new and previously reported modules of PETSTEP (PET Simulator of Tracers via Emission Projection). Time activity curves are generated for each voxel of the input parametric image, whereby effects of imaging system blurring, counting noise, scatters, randoms, and attenuation are simulated for each frame. Each frame is then reconstructed into images according to the user specified method, settings, and corrections. Reconstructed images were compared to MC data, and simple Gaussian noised time activity curves (GAUSS). Results: dPETSTEP was 8000 times faster than MC. Dynamic images from dPETSTEP had a root mean square error that was within 4% on average of that of MC images, whereas the GAUSS images were within 11%. The average bias in dPETSTEP and MC images was the same, while GAUSS differed by 3% points. Noise profiles in dPETSTEP images conformed well to MC images, confirmed visually by scatter plot histograms, and statistically by tumor region of interest histogram comparisons that showed no significant differences (p < 0.01). Compared to GAUSS, dPETSTEP images and noise properties agreed better with MC. Conclusions: The authors have developed a fast and easy one-stop solution for simulations of dynamic PET and parametric images, and demonstrated that it generates both images and subsequent parametric images with very similar noise properties to those of MC images, in a fraction of the time. They believe dPETSTEP to be very useful for generating fast, simple, and realistic results, however since it uses simple scatter and random models it may not be suitable for

  11. Dynamic PET simulator via tomographic emission projection for kinetic modeling and parametric image studies

    International Nuclear Information System (INIS)

    Häggström, Ida; Beattie, Bradley J.; Schmidtlein, C. Ross

    2016-01-01

    Purpose: To develop and evaluate a fast and simple tool called dPETSTEP (Dynamic PET Simulator of Tracers via Emission Projection), for dynamic PET simulations as an alternative to Monte Carlo (MC), useful for educational purposes and evaluation of the effects of the clinical environment, postprocessing choices, etc., on dynamic and parametric images. Methods: The tool was developed in MATLAB using both new and previously reported modules of PETSTEP (PET Simulator of Tracers via Emission Projection). Time activity curves are generated for each voxel of the input parametric image, whereby effects of imaging system blurring, counting noise, scatters, randoms, and attenuation are simulated for each frame. Each frame is then reconstructed into images according to the user specified method, settings, and corrections. Reconstructed images were compared to MC data, and simple Gaussian noised time activity curves (GAUSS). Results: dPETSTEP was 8000 times faster than MC. Dynamic images from dPETSTEP had a root mean square error that was within 4% on average of that of MC images, whereas the GAUSS images were within 11%. The average bias in dPETSTEP and MC images was the same, while GAUSS differed by 3% points. Noise profiles in dPETSTEP images conformed well to MC images, confirmed visually by scatter plot histograms, and statistically by tumor region of interest histogram comparisons that showed no significant differences (p < 0.01). Compared to GAUSS, dPETSTEP images and noise properties agreed better with MC. Conclusions: The authors have developed a fast and easy one-stop solution for simulations of dynamic PET and parametric images, and demonstrated that it generates both images and subsequent parametric images with very similar noise properties to those of MC images, in a fraction of the time. They believe dPETSTEP to be very useful for generating fast, simple, and realistic results, however since it uses simple scatter and random models it may not be suitable for

  12. The utility of FDG-PET for assessing outcomes in oligometastatic cancer patients treated with stereotactic body radiotherapy: a cohort study

    Directory of Open Access Journals (Sweden)

    Solanki Abhishek A

    2012-12-01

    Full Text Available Abstract Background Studies suggest that patients with metastases limited in number and destination organ benefit from metastasis-directed therapy. Stereotactic body radiotherapy (SBRT is commonly used for metastasis directed therapy in this group. However, the characterization of PET response following SBRT is unknown in this population. We analyzed our cohort of patients to describe the PET response following SBRT. Methods Patients enrolled on a prospective dose escalation trial of SBRT to all known sites of metastatic disease were reviewed to select patients with pre- and post-therapy PET scans. Response to SBRT was characterized on PET imaging based on standard PET response criteria and compared to CT based RECIST criteria for each treated lesion. Results 31 patients had PET and CT data available before and after treatment for analysis in this study. In total, 58 lesions were treated (19 lung, 11 osseous, 11 nodal, 9 liver, 6 adrenal and 2 soft tissue metastases. Median follow-up was 14 months (range: 3–41. Median time to first post-therapy PET was 1.2 months (range; 0.5-4.1. On initial post-therapy PET evaluation, 96% (56/58 of treated metastases responded to therapy. 60% (35/58 had a complete response (CR on PET and 36% (21/58 had a partial response (PR. Of 22 patients with stable disease (SD on initial CT scan, 13 had CR on PET, 8 had PR, and one had SD. Of 21 metastases with PET PR, 38% became CR, 52% remained PR, and 10% had progressive disease on follow-up PET. 10/35 lesions (29% with an initial PET CR progressed on follow-up PET scan with median time to progression of 4.11 months (range: 2.75-9.56. Higher radiation dose correlated with long-term PET response. Conclusions PET response to SBRT enables characterization of metastatic response in tumors non-measurable by CT. Increasing radiation dose is associated with prolonged complete response on PET.

  13. [11C]CHIBA-1001 as a novel PET ligand for alpha7 nicotinic receptors in the brain: a PET study in conscious monkeys.

    Directory of Open Access Journals (Sweden)

    Kenji Hashimoto

    Full Text Available BACKGROUND: The alpha7 nicotinic acetylcholine receptors (nAChRs play an important role in the pathophysiology of neuropsychiatric diseases such as schizophrenia and Alzheimer's disease. However, there are currently no suitable positron emission tomography (PET radioligands for imaging alpha7 nAChRs in the intact human brain. Here we report the novel PET radioligand [11C]CHIBA-1001 for in vivo imaging of alpha7 nAChRs in the non-human primate brain. METHODOLOGY/PRINCIPAL FINDINGS: A receptor binding assay showed that CHIBA-1001 was a highly selective ligand at alpha7 nAChRs. Using conscious monkeys, we found that the distribution of radioactivity in the monkey brain after intravenous administration of [11C]CHIBA-1001 was consistent with the regional distribution of alpha7 nAChRs in the monkey brain. The distribution of radioactivity in the brain regions after intravenous administration of [11C]CHIBA-1001 was blocked by pretreatment with the selective alpha7 nAChR agonist SSR180711 (5.0 mg/kg. However, the distribution of [11C]CHIBA-1001 was not altered by pretreatment with the selective alpha4beta2 nAChR agonist A85380 (1.0 mg/kg. Interestingly, the binding of [11C]CHIBA-1001 in the frontal cortex of the monkey brain was significantly decreased by subchronic administration of the N-methyl-D-aspartate (NMDA receptor antagonist phencyclidine (0.3 mg/kg, twice a day for 13 days; which is a non-human primate model of schizophrenia. CONCLUSIONS/SIGNIFICANCE: The present findings suggest that [11C]CHIBA-1001 could be a novel useful PET ligand for in vivo study of the receptor occupancy and pathophysiology of alpha7 nAChRs in the intact brain of patients with neuropsychiatric diseases such as schizophrenia and Alzheimer's disease.

  14. A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

    International Nuclear Information System (INIS)

    Kaminska, D.; Gajos, A.; Czerwinski, E.; Alfs, D.; Bednarski, T.; Bialas, P.; Dulski, K.; Glowacz, B.; Gupta-Sharma, N.; Korcyl, G.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedzwiecki, Sz.; Pawlik-Niedzwiecka, M.; Rudy, Z.; Wieczorek, A.; Zielinski, M.; Moskal, P.; Curceanu, C.; Silarski, M.; Gorgol, M.; Jasinska, B.; Zgardzinska, B.; Hiesmayr, B.C.; Kowalski, P.; Raczynski, L.; Wislicki, W.; Krzemien, W.

    2016-01-01

    We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the o-Ps → 3γ decays with angular and energy resolution equal to σ(θ) ∼ 0.4 circle and σ(E) ∼ 4.1 keV, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities. (orig.)

  15. A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Kaminska, D.; Gajos, A.; Czerwinski, E.; Alfs, D.; Bednarski, T.; Bialas, P.; Dulski, K.; Glowacz, B.; Gupta-Sharma, N.; Korcyl, G.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedzwiecki, Sz.; Pawlik-Niedzwiecka, M.; Rudy, Z.; Wieczorek, A.; Zielinski, M.; Moskal, P. [Jagiellonian University, Faculty of Physics, Astronomy and Applied Computer Science, Krakow (Poland); Curceanu, C.; Silarski, M. [INFN, Laboratori Nazionali di Frascati, CP 13, Frascati (Italy); Gorgol, M.; Jasinska, B.; Zgardzinska, B. [Maria Curie-Sklodowska University, Department of Nuclear Methods, Institute of Physics, Lublin (Poland); Hiesmayr, B.C. [University of Vienna, Faculty of Physics, Vienna (Austria); Kowalski, P.; Raczynski, L.; Wislicki, W. [Swierk Computing Centre, National Centre for Nuclear Research, Otwock-Swierk (Poland); Krzemien, W. [National Centre for Nuclear Research, High Energy Department, Otwock-Swierk (Poland)

    2016-08-15

    We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the o-Ps → 3γ decays with angular and energy resolution equal to σ(θ) ∼ 0.4 {sup circle} and σ(E) ∼ 4.1 keV, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities. (orig.)

  16. A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

    Science.gov (United States)

    Kamińska, D.; Gajos, A.; Czerwiński, E.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Dulski, K.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Korcyl, G.; Kowalski, P.; Krzemień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Pawlik-Niedźwiecka, M.; Raczyński, L.; Rudy, Z.; Silarski, M.; Wieczorek, A.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

    2016-08-01

    We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the { o-Ps }→ 3γ decays with angular and energy resolution equal to σ (θ ) ≈ {0.4°} and σ (E) ≈ 4.1 {keV}, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities.

  17. Clinical utility of flumazenil-PET versus [18F]fluorodeoxyglucose-PET and MRI in refractory partial epilepsy. A prospective study in 100 patients.

    Science.gov (United States)

    Ryvlin, P; Bouvard, S; Le Bars, D; De Lamérie, G; Grégoire, M C; Kahane, P; Froment, J C; Mauguière, F

    1998-11-01

    We assessed the clinical utility of [11C]flumazenil-PET (FMZ-PET) prospectively in 100 epileptic patients undergoing a pre-surgical evaluation, and defined the specific contribution of this neuro-imaging technique with respect to those of MRI and [18F]fluorodeoxyglucose-PET (FDG-PET). All patients benefited from a long term video-EEG monitoring, whereas an intracranial EEG investigation was performed in 40 cases. Most of our patients (73%) demonstrated a FMZ-PET abnormality; this hit rate was significantly higher in temporal lobe epilepsy (94%) than in other types of epilepsy (50%) (P lobe epilepsy associated with MRI signs of hippocampal sclerosis, FMZ-PET abnormalities delineated the site of seizure onset precisely, whenever they were coextensive with FDG-PET abnormalities; (ii) in bi-temporal epilepsy, FMZ-PET helped to confirm the bilateral origin of seizures by showing a specific pattern of decreased FMZ binding in both temporal lobes in 33% of cases; (iii) in patients with a unilateral cryptogenic frontal lobe epilepsy, FMZ-PET provided further evidence of the side and site of seizure onset in 55% of cases. Thus, FMZ-PET deserves to be included in the pre-surgical evaluation of these specific categories of epileptic patients, representing approximately half of the population considered for epilepsy surgery.

  18. Carbon-11 labelled ketamine-synthesis, distribution in mice and PET studies in baboons

    International Nuclear Information System (INIS)

    Shiue, C.-Y.; Vallabhahosula, Shankar; Wolf, Alfred P.; Dewey, Stephen L.; Fowler, Joanna S.; Schlyer, David J.; Arnett, Carroll D.; Zhou Yiguo

    1997-01-01

    No-carrier-added (NCA)[ 11 C](±)-ketamine (2a) and its enantiomers (+)-2b and (-)-2c were synthesized by methylation of the corresponding norketamine (1a-c) with [ 11 C]H 3 I in an overall radiochemical yield of 20% (EOB) with specific activities of 0.35-0.45 Ci/μmole at EOB in a synthesis time of 40 min from EOB. Compound 2a was metabolized rapidly in mouse brain and labeled metabolites appeared in baboon plasma. PET studies of compounds 2a-c in a baboon showed that influx of compounds 2a-c into the brain was high for the first few min but radioactivity then declined rapidly. Although the retention of radioactivity in the baboon striatum was not significantly different for 2a-c 20 min post-injection, graphical analysis of time-activity data for each enantiomer and for the racemate in baboon striatum suggested that (+)-ketamine may interact with receptors slightly more effectively than its (-)-enantiomer or racemate. However, due to its rapid metabolism in the brain and a similar uptake in the striatum and cerebellum, [ 11 C]ketamine may not be an ideal tracer for studying NMDA receptor with PET

  19. Carbon-11 labelled ketamine-synthesis, distribution in mice and PET studies in baboons

    Energy Technology Data Exchange (ETDEWEB)

    Shiue, C.-Y.; Vallabhahosula, Shankar; Wolf, Alfred P.; Dewey, Stephen L.; Fowler, Joanna S.; Schlyer, David J.; Arnett, Carroll D.; Zhou Yiguo

    1997-02-01

    No-carrier-added (NCA)[{sup 11}C]({+-})-ketamine (2a) and its enantiomers (+)-2b and (-)-2c were synthesized by methylation of the corresponding norketamine (1a-c) with [{sup 11}C]H{sub 3}I in an overall radiochemical yield of 20% (EOB) with specific activities of 0.35-0.45 Ci/{mu}mole at EOB in a synthesis time of 40 min from EOB. Compound 2a was metabolized rapidly in mouse brain and labeled metabolites appeared in baboon plasma. PET studies of compounds 2a-c in a baboon showed that influx of compounds 2a-c into the brain was high for the first few min but radioactivity then declined rapidly. Although the retention of radioactivity in the baboon striatum was not significantly different for 2a-c 20 min post-injection, graphical analysis of time-activity data for each enantiomer and for the racemate in baboon striatum suggested that (+)-ketamine may interact with receptors slightly more effectively than its (-)-enantiomer or racemate. However, due to its rapid metabolism in the brain and a similar uptake in the striatum and cerebellum, [{sup 11}C]ketamine may not be an ideal tracer for studying NMDA receptor with PET.

  20. Positron emission tomography (PET) studies of dopaminergic/cholinergic interactions in the baboon brain

    International Nuclear Information System (INIS)

    Dewey, S.L.; Brodie, J.D.; Fowler, J.S.; MacGregor, R.R.; Schlyer, D.J.; King, P.T.; Alexoff, D.L.; Volkow, N.D.; Shiue, C.Y.; Wolf, A.P.

    1990-01-01

    Interactions between the dopaminergic D2 receptor system and the muscarinic cholinergic system in the corpus striatum of adult female baboons (Papio anubis) were examined using positron emission tomography (PET) combined with [18F]N-methylspiroperidol [( 18F]NMSP) (to probe D2 receptor availability) and [N-11C-methyl]benztropine (to probe muscarinic cholinergic receptor availability). Pretreatment with benztropine, a long-lasting anticholinergic drug, bilaterally reduced the incorporation of radioactivity in the corpus striatum but did not alter that observed in the cerebellum or the rate of metabolism of [18F]NMSP in plasma. Pretreatment with unlabelled NMSP, a potent dopaminergic antagonist, reduced the incorporation of [N-11C-methyl]benztropine in all brain regions, with the greatest effect being in the corpus striatum greater than cortex greater than thalamus greater than cerebellum, but did not alter the rate of metabolism of the labelled benztropine in the plasma. These reductions in the incorporation of either [18F]NMSP or [N-11C-methyl]benztropine exceeded the normal variation in tracer incorporation in repeated studies in the same animal. This study demonstrates that PET can be used as a tool for investigating interactions between neurochemically different yet functionally linked neurotransmitters systems in vivo and provides insight into the consequences of multiple pharmacologic administration

  1. Impact of contamination with long-lived radionuclides on PET kinetics modelling in multitracer studies

    DEFF Research Database (Denmark)

    Jødal, Lars; Hansen, Søren Baarsgaard; Jensen, Svend B

    2016-01-01

    Introduction: An important issue in multitracer studies is the separation of signals from the different radiotracers. This is especially the case when an early tracer has a long physical half-life and kinetic modelling has to be performed, because the early tracer can confer a long-lived contamin......Introduction: An important issue in multitracer studies is the separation of signals from the different radiotracers. This is especially the case when an early tracer has a long physical half-life and kinetic modelling has to be performed, because the early tracer can confer a long...... of subsequent PET tracers. Blood sample counts were corrected by recounting the samples a few days later. A more optimal choice of energy window was also explored. The effect of correction versus noncorrection was investigated using a two-tissue kinetic model with irreversible uptake (K1, k2, k3). Results: K1...... counting of blood samples can lead to a contaminating background not observed in PET imaging and this background can affect kinetic modelling. If the contaminating tracer has a much longer half-life than the foreground tracer, then the problem can be solved by late recounting of the samples....

  2. Clinical significance of reduced cerebral metabolism in multiple sclerosis. A combined PET and MRI study

    International Nuclear Information System (INIS)

    Sun, Xiayan; Tanaka, Makoto; Kondo, Susumu; Okamoto, Koichi; Hirai, Shunsaku

    1998-01-01

    Magnetic resonance imaging (MRI) in patients with multiple sclerosis (MS) has provided major insights into the disease's natural history, and many studies have focussed on possible correlations between MRI findings and the clinical manifestations of MS. In contrast, there are few reports on possible relationships between functional imaging data and cognitive function. The present study assessed the relationship between clinical presentation and combined anatomical and functional imaging data in MS. Twenty patients with definite MS underwent MRI and positron emission tomography (PET) to evaluate cerebral blood flow (rCBF) and oxygen metabolism (rCMRO 2 ). The relationships between these neuroimaging findings and clinical data, including the Expanded Disability Status Scale (EDSS), Mini-mental status scale, Hasegawa Dementia Scale and relapse time, were evaluated with Spearman's rank correlation coefficients. A general reduction in rCBF and rCMRO 2 in the gray and white matter were found in the MS patients. EDSS was correlated with the number and size of the lesions on MRI and was negatively correlated with rCMRO 2 . A correlation between the decrease in rCMRO 2 and the level of cognitive impairment was also found. The severity of cerebral hypometabolism was also related to the number of relapses. Morphological and functional findings obtained by MRI and PET are closely related to the clinical status in MS. Our results suggest that measurement of cerebral metabolism in MS has the potential to be an objective marker for monitoring disease activity and to provide prognostic information. (author)

  3. Initial studies using the RatCAP conscious animal PET tomograph

    Energy Technology Data Exchange (ETDEWEB)

    Woody, C. [Brookhaven National Laboratory, Upton, NY (United States)]. E-mail: woody@bnl.gov; Vaska, P. [Brookhaven National Laboratory, Upton, NY (United States); Schlyer, D. [Brookhaven National Laboratory, Upton, NY (United States); Pratte, J.-F. [Brookhaven National Laboratory, Upton, NY (United States); Junnarkar, S. [Brookhaven National Laboratory, Upton, NY (United States); Park, S.-J. [Brookhaven National Laboratory, Upton, NY (United States); Stoll, S. [Brookhaven National Laboratory, Upton, NY (United States); Purschke, M. [Brookhaven National Laboratory, Upton, NY (United States); Southekal, S. [Stony Brook University, Stony Brook, NY (United States); Kriplani, A. [Stony Brook University, Stony Brook, NY (United States); Krishnamoorthy, S. [Stony Brook University, Stony Brook, NY (United States); Maramraju, S. [Stony Brook University, Stony Brook, NY (United States); Lee, D. [Brookhaven National Laboratory, Upton, NY (United States); Schiffer, W. [Brookhaven National Laboratory, Upton, NY (United States); Dewey, S. [Brookhaven National Laboratory, Upton, NY (United States); Neill, J. [Long Island University, Brookville, NY (United States); Kandasamy, A. [Brookhaven National Laboratory, Upton, NY (United States); O' Connor, P. [Brookhaven National Laboratory, Upton, NY (United States); Radeka, V. [Brookhaven National Laboratory, Upton, NY (United States); Fontaine, R. [Sherbrooke University, Sherbrooke, Que. (Canada); Lecomte, R. [Sherbrooke University, Sherbrooke, Que. (Canada)

    2007-02-01

    The RatCAP is a small, head-mounted PET tomograph designed to image the brain of a conscious rat without the use of anesthesia. The detector is a complete, high-performance 3D tomograph consisting of a 3.8 cm inside-diameter ring containing 12 block detectors, each of which is comprised of a 4x8 array of 2.2x2.2x5 mm{sup 3} LSO crystals readout with a matching APD array and custom ASIC, and has a 1.8 cm axial field of view. Construction of the first working prototype detector has been completed and its performance characteristics have been measured. The results show an intrinsic spatial resolution of 2.1 mm, a time resolution of {approx}14 ns FWHM, and a sensitivity of 0.7% at an energy threshold of 150 keV. First preliminary images have been obtained using {sup 18}F-FDG and {sup 11}C-methamphetamine, which show comparable image quality to those obtained from a commercial MicroPET R4 scanner. Initial studies have also been carried out to study stress levels in rats wearing the RatCAP.

  4. Initial studies using the RatCAP conscious animal PET tomograph

    International Nuclear Information System (INIS)

    Woody, C.; Vaska, P.; Schlyer, D.; Pratte, J.-F.; Junnarkar, S.; Park, S.-J.; Stoll, S.; Purschke, M.; Southekal, S.; Kriplani, A.; Krishnamoorthy, S.; Maramraju, S.; Lee, D.; Schiffer, W.; Dewey, S.; Neill, J.; Kandasamy, A.; O'Connor, P.; Radeka, V.; Fontaine, R.; Lecomte, R.

    2007-01-01

    The RatCAP is a small, head-mounted PET tomograph designed to image the brain of a conscious rat without the use of anesthesia. The detector is a complete, high-performance 3D tomograph consisting of a 3.8 cm inside-diameter ring containing 12 block detectors, each of which is comprised of a 4x8 array of 2.2x2.2x5 mm 3 LSO crystals readout with a matching APD array and custom ASIC, and has a 1.8 cm axial field of view. Construction of the first working prototype detector has been completed and its performance characteristics have been measured. The results show an intrinsic spatial resolution of 2.1 mm, a time resolution of ∼14 ns FWHM, and a sensitivity of 0.7% at an energy threshold of 150 keV. First preliminary images have been obtained using 18 F-FDG and 11 C-methamphetamine, which show comparable image quality to those obtained from a commercial MicroPET R4 scanner. Initial studies have also been carried out to study stress levels in rats wearing the RatCAP

  5. A Monte Carlo study of the acceptance to scattered events in a depth encoding PET camera

    International Nuclear Information System (INIS)

    Moisan, C.; Tupper, P.; Rogers, J.G.; DeJong, J.K.

    1995-10-01

    We present a Monte Carlo study of acceptance to scattered events in a Depth Encoding Large Aperture Camera (DELAC), a hypothetical PET scanner with the capacity to encode the depth-of-interaction (DOI) of incident γ-rays. The simulation is initially validated against the measured energy resolution and scatter fraction of the ECAT-953B scanner. It is then used to assess the response to scattered events in a PET camera made of position encoding blocks of the EXACT HR PLUS type, modified to have DOI resolution through a variation in the photopeak pulse height. The detection efficiency for 511 keV γ-rays, as well as for those that scattered in the object or left only part of their energy in the block, is studied for several combinations of DOI sensitivities and block thicknesses. The scatter fraction predicted by the simulation for DELACs of various ring radii is compared to that of the ECAT-953B as a function of the energy threshold. The results indicate that the poorer discrimination of object scatters with depth sensitive blocks does not lead to a dramatic increase of the scatter fraction. (author). 10 refs., 1 tab., 5 figs

  6. Pet exposure and risk of atopic dermatitis at the pediatric age: a meta-analysis of birth cohort studies.

    Science.gov (United States)

    Pelucchi, Claudio; Galeone, Carlotta; Bach, Jean-François; La Vecchia, Carlo; Chatenoud, Liliane

    2013-09-01

    Findings on pet exposure and the risk of atopic dermatitis (AD) in children are inconsistent. With the aim to summarize the results of exposure to different pets on AD, we undertook a meta-analysis of epidemiologic studies on this issue. In August 2012, we conducted a systematic literature search in Medline and Embase. We included analytic studies considering exposure to dogs, cats, other pets, or pets overall during pregnancy, infancy, and/or childhood, with AD assessment performed during infancy or childhood. We calculated summary relative risks and 95% CIs using both fixed- and random-effects models. We computed summary estimates across selected subgroups. Twenty-six publications from 21 birth cohort studies were used in the meta-analyses. The pooled relative risks of AD for exposure versus no exposure were 0.72 (95% CI, 0.61-0.85; I(2) = 46%; results based on 15 studies) for exposure to dogs, 0.94 (95% CI, 0.76-1.16; I(2) = 54%; results based on 13 studies) for exposure to cats, and 0.75 (95% CI, 0.67-0.85; I(2) = 54%; results based on 11 studies) for exposure to pets overall. No heterogeneity emerged across the subgroups examined, except for geographic area. This meta-analysis reported a favorable effect of exposure to dogs and pets on the risk of AD in infants or children, whereas no association emerged with exposure to cats. Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

  7. Study on the application of PET-CT in gynecology tumors

    International Nuclear Information System (INIS)

    Wen Lilian

    2012-01-01

    Gynecology tumors seriously threatened the health of female. With the development of imageology, PET, a functionality examination method, has been widely used in the early diagnosis and monitoring of curative effect in gynecology tumors. PET-CT has the good future in its development because it combined with the advantage of functional and structural imaging. The characters and application of PET-CT in gynecology tumors were reviewed in this paper. (author)

  8. Normal uptake of F-18 FDG in the testis as assessed by PET/CT in a pediatric study population

    International Nuclear Information System (INIS)

    Goethals, I.; Vriendt, C.D.; Hoste, P.; Smeets, P.; Ham, H.

    2009-01-01

    The objective of this study was to investigate the correlation between the F-18 fluorodeoxyglucose (FDG) uptake in the normal testis as assessed by positron emission tomography (PET)-CT and patient age in a pediatric study population. The study population consisted of 22 subjects aged between 9 and 17 years. For these subjects 42 PET-CT scans were available for analysis. The testis was identified on the CT images. Mean standard uptake values and testicular volume were calculated based on manually drawn regions-of-interest over the organ. The correlation between mean standardized uptake value (SUV) and age as well as between testicular volume and age was calculated using Pearson's correlation coefficient. A strong and statistically significant positive correlation between F-18 FDG uptake in the testis and age was documented. The correlation coefficient was 0.406 in the analysis based on 42 PET-CT studies (p=0.005). The correlation between tracer uptake and age was reassessed based on 22 PET-CT studies including the last recorded PET-CT scan per patient. The correlation coefficient was 0.409 (p=0.05). In addition, based on 22 PET-CT scans, a strong and statistically significant positive correlation between testicular volume and age was documented (r=0.67, p<0.001). Whereas it was previously shown that in adult men there was a weak but statistically significant negative correlation between F-18 FDG uptake in the normal testis and age, we found a strong and statistically significant positive correlation in children and teenage boys. (author)

  9. Studies oriented to optimize the image quality of the small animal PET: Clear PET, modifying some of the parameters of the reconstruction algorithm IMF-OSEM 3D on the data acquisition simulated with GAMOS

    International Nuclear Information System (INIS)

    Canadas, M.; Mendoza, J.; Embid, M.

    2007-01-01

    This report presents studies oriented to optimize the image quality of the small animal PET: Clear- PET. Certain figures of merit (FOM) were used to assess a quantitative value of the contrast and delectability of lesions. The optimization was carried out modifying some of the parameters in the reconstruction software of the scanner, imaging a mini-Derenzo phantom and a cylinder phantom with background activity and two hot spheres. Specifically, it was evaluated the incidence of the inter-update Metz filter (IMF) inside the iterative reconstruction algorithm 3D OSEM. The data acquisition was simulated using the GAMOS framework (Monte Carlo simulation). Integrating GAMOS output with the reconstruction software of the scanner was an additional novelty of this work, to achieve this, data sets were written with the list-mode format (LMF) of ClearPET. In order to verify the optimum values obtained, we foresee to make real acquisitions in the ClearPET of CIEMAT. (Author) 17 refs

  10. PET/CT imaging for treatment verification after proton therapy: a study with plastic phantoms and metallic implants.

    Science.gov (United States)

    Parodi, Katia; Paganetti, Harald; Cascio, Ethan; Flanz, Jacob B; Bonab, Ali A; Alpert, Nathaniel M; Lohmann, Kevin; Bortfeld, Thomas

    2007-02-01

    The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. It also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of

  11. A primary study on meridian-stretching of injected FDG using PET MPItool

    International Nuclear Information System (INIS)

    He Yijie; Tian Jiahe; Chen Yingmao; Yin Dayi; Zhang Jinming; Zhang Shuwen; Shao Mingzhe; Yao Shulin; Ding Weimin; Liu Zilai

    2002-01-01

    Objective: To show the images of tracer-stretching along the acupuncture meridian by use of PET with multipurpose imaging tool (MPItool's) fusion function. Methods: On 5 healthy volunteers, the authors measured the classical acupuncture points accurately with the biophysical measuring method. 18 F-fluorodeoxyglucose (FDG) was injected into the selected points, the others points along the same meridian were labelled with 18 F-FDG applied on the correspondent skin area of 2 . With the same body position, the transmission image and emission image was acquired respectively and fused with MPItool and its 3D display system. Results: The authors clearly showed not only the meridian-stretching images of the tracer, but also figured out the depth of the study points. The depth at SHANGJUXU point was about 3.8 cm and at ZUSANLI point was about 5,0 cm. The depths basically fit the classically documented ones of the correspondent acupuncture points. Conclusions: Using PET MPItool the authors preliminarily demonstrated that the tracer injected at the acupuncture point stretches along the correspondent meridian, and the depths of the meridian and the points (SHANGJUXU, ZUSANLI) detected are almost accordant with the classically documented ones

  12. Study of a high-resolution, 3-D positioning cadmium zinc telluride detector for PET

    Science.gov (United States)

    Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

    2011-01-01

    This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV throughout most the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44±0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78±0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes – as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system. PMID:21335649

  13. Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET.

    Science.gov (United States)

    Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

    2011-03-21

    This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 ± 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 ± 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 ± 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes-as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

  14. Hilar activity on the F-18 FDG whole-body PET studies

    International Nuclear Information System (INIS)

    Fujii, Hirofumi; Kitamura, Masayuki; Kubo, Atsushi; Yasuda, Seiei; Ide, Michiru; Takahashi, Wakoh; Shohtsu, Akira

    1999-01-01

    We evaluated the clinical characteristics of hilar activity that would be false positive findings for cancer screening on whole-body FDG PET. The cases with increased hilar activity were selected from 1,126 cases who received whole-body FDG PET between September 1996 and August 1997, and their age, sex, complication of inflammatory process in lungs, numbers of visualized mediastinal lymph nodes, frequency of smoking, blood sugar level and concentration of HbA1c were studied. FDG accumulation in the hilar regions was found in 63 cases (5.6%). The cases with increased hilar activity were older, a higher incidence of complication of pulmonary inflammation, a larger number of visualized mediastinal lymph nodes and were more frequent smokers than the control cases with normal FDG distribution. Their male-to-female ratio, blood sugar level and concentration of HbA1c were not significantly different from those of the control cases. These results suggested that an inflammatory process around the hilar region might induce this confusing FDG accumulation. (author)

  15. High prevalence of thyroid FDG uptake on PET study in patients with thyroid hormone replacement

    International Nuclear Information System (INIS)

    Yu, J.-Q.; Kumar, R.; Xiu, Y.; Dadparvar, S.; Kung, J.W.; Kunjunmen, B.D.; Feng, Q.; Alavi, A.; Zhuang, H.

    2004-01-01

    Thyroid uptake is commonly seen on whole-body FDG-PET images. One well-known cause for this uptake is hyperthyroidism. The purpose of this study was to determine whether hypothyroidism also affects FDG uptake by the thyroid gland. Hospital records of 2765 patients who had undergone whole-body FDG-PET imaging for malignancies were retrospectively reviewed. Among them, those who had thyroid cancer, history of thyroid ablation for hyperthyroidism, neck lymphoma, and other types of head and neck cancer or recent neck surgery were excluded from analysis. The prevalence and level of thyroid FDG uptake in the remaining 1939 patients was compared with the state of patients' thyroid function. There were 141 hypothyroid subjects and the rest (n=1798) were euthyroid. The prevalence of thyroid tissue uptake in euthyroid subjects was 2.34% (42 of 1798), while it was 22% (31 out of 141) in hypothyroid patients. This was statistically significant. Similarly, the prevalence of hypothyroidism in patients in patients showing thyroid uptake was 42.5% (31 of 73), while it was 5.9% (110 of 1866) in patients without thyroid uptake. This was again statistically significant (p<0.001). Based on this retrospective analysis it was concluded that the prevalence of increased thyroid FDG uptake is significantly higher in patients with hypothyroidism than those who are euthyroid. (author)

  16. Sensitivity study of voxel-based PET image comparison to image registration algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Yip, Stephen, E-mail: syip@lroc.harvard.edu; Chen, Aileen B.; Berbeco, Ross [Department of Radiation Oncology, Brigham and Women’s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States); Aerts, Hugo J. W. L. [Department of Radiation Oncology, Brigham and Women’s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 and Department of Radiology, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts 02115 (United States)

    2014-11-01

    Purpose: Accurate deformable registration is essential for voxel-based comparison of sequential positron emission tomography (PET) images for proper adaptation of treatment plan and treatment response assessment. The comparison may be sensitive to the method of deformable registration as the optimal algorithm is unknown. This study investigated the impact of registration algorithm choice on therapy response evaluation. Methods: Sixteen patients with 20 lung tumors underwent a pre- and post-treatment computed tomography (CT) and 4D FDG-PET scans before and after chemoradiotherapy. All CT images were coregistered using a rigid and ten deformable registration algorithms. The resulting transformations were then applied to the respective PET images. Moreover, the tumor region defined by a physician on the registered PET images was classified into progressor, stable-disease, and responder subvolumes. Particularly, voxels with standardized uptake value (SUV) decreases >30% were classified as responder, while voxels with SUV increases >30% were progressor. All other voxels were considered stable-disease. The agreement of the subvolumes resulting from difference registration algorithms was assessed by Dice similarity index (DSI). Coefficient of variation (CV) was computed to assess variability of DSI between individual tumors. Root mean square difference (RMS{sub rigid}) of the rigidly registered CT images was used to measure the degree of tumor deformation. RMS{sub rigid} and DSI were correlated by Spearman correlation coefficient (R) to investigate the effect of tumor deformation on DSI. Results: Median DSI{sub rigid} was found to be 72%, 66%, and 80%, for progressor, stable-disease, and responder, respectively. Median DSI{sub deformable} was 63%–84%, 65%–81%, and 82%–89%. Variability of DSI was substantial and similar for both rigid and deformable algorithms with CV > 10% for all subvolumes. Tumor deformation had moderate to significant impact on DSI for progressor

  17. Added diagnostic value of respiratory-gated 4D 18F-FDG PET/CT in the detection of liver lesions. A multicenter study

    Energy Technology Data Exchange (ETDEWEB)

    Crivellaro, Cinzia; Landoni, Claudio; Guerra, Luca [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); University of Milan-Bicocca, Milan (Italy); De Ponti, Elena; Morzenti, Sabrina [San Gerardo Hospital, Medical Physics, Monza (Italy); Elisei, Federica [San Gerardo Hospital, Nuclear Medicine, Monza (Italy); Picchio, Maria; Bettinardi, Valentino [IRCCS San Raffaele Scientific Institute, Nuclear Medicine, Milan (Italy); Versari, Annibale [Santa Maria Nuova Hospital IRCCS, Nuclear Medicine, Reggio Emilia (Italy); Fioroni, Federica [Santa Maria Nuova Hospital IRCCS, Medical Physics, Reggio Emilia (Italy); Dziuk, Miroslaw; Tkaczewski, Konrad [Military Institute of Medicine, Warsaw (Poland); Ahond-Vionnet, Renee; Nodari, Guillaume [Hopital Pierre Beregovoy, Service de Medecine Nucleaire, Nevers (France); Todde, Sergio [University of Milan-Bicocca, Tecnomed Foundation, Monza (Italy)

    2018-01-15

    The aim of the present study was to evaluate the added diagnostic value of respiratory-gated 4D18F-FDG PET/CT in liver lesion detection and characterization in a European multicenter retrospective study. Fifty-six oncological patients (29 males and 27 females, mean age, 61.2 ± 11.2 years) from five European centers, submitted to standard 3D-PET/CT and liver 4D-PET/CT were retrospectively evaluated. Based on visual analysis, liver PET/CT findings were scored as positive, negative, or equivocal both in 3D and 4D PET/CT. The impact of 4D-PET/CT on the confidence in classifying liver lesions was assessed. PET/CT findings were compared to histology and clinical follow-up as standard reference and diagnostic accuracy was calculated for both techniques. At semi-quantitative analysis, SUVmax was calculated for each detected lesion in 3D and 4D-PET/CT. Overall, 72 liver lesions were considered for the analysis. Based on visual analysis in 3D-PET/CT, 32/72 (44.4%) lesions were considered positive, 21/72 (29.2%) negative, and 19/72 (26.4%) equivocal, while in 4D-PET/CT 48/72 (66.7%) lesions were defined positive, 23/72 (31.9%) negative, and 1/72 (1.4%) equivocal. 4D-PET/CT findings increased the confidence in lesion definition in 37/72 lesions (51.4%). Considering 3D equivocal lesions as positive, sensitivity, specificity, and accuracy were 88.9, 70.0, and 83.1%, respectively, while the same figures were 67.7, 90.0, and 73.8% if 3D equivocal findings were included as negative. 4D-PET/CT sensitivity, specificity, and accuracy were 97.8, 90.0, and 95.4%, respectively, considering equivocal lesions as positive and 95.6, 90.0, and 93.8% considering equivocal lesions as negative. The SUVmax of the liver lesions in 4D-PET (mean ± SD, 6.9 ± 3.2) was significantly higher (p < 0.001) than SUVmax in 3D-PET (mean ± SD, 5.2 ± 2.3). Respiratory-gated PET/CT technique is a valuable clinical tool in diagnosing liver lesions, reducing 3D undetermined findings, improving diagnostic

  18. Response assessment of bevacizumab therapy in GBM with integrated 11C-MET-PET/MRI: a feasibility study.

    Science.gov (United States)

    Deuschl, Cornelius; Moenninghoff, Christoph; Goericke, Sophia; Kirchner, Julian; Köppen, Susanne; Binse, Ina; Poeppel, Thorsten D; Quick, Harald H; Forsting, Michael; Umutlu, Lale; Herrmann, Ken; Hense, Joerg; Schlamann, Marc

    2017-08-01

    The objective of this study was to evaluate the potential of integrated 11C-MET PET/MR for response assessment of relapsed glioblastoma (GBM) receiving bevacizumab treatment. Eleven consecutive patients with relapsed GBM were enrolled for an integrated 11C-MET PET/MRI at baseline and at follow-up. Treatment response for MRI was evaluated according to Response Assessment in Neuro-oncology (RANO) criteria and integrated 11C-MET PET was assessed by the T/N ratio. MRI showed no patient with complete response (CR), six of 11 patients with PR, four of 11 patients with SD, and one of 11 patients with progressive disease (PD). PET revealed metabolic response in five of the six patients with partial response (PR) and in two of the four patients with stable disease (SD), whereas metabolic non-response was detected in one of the six patients with PR, in two of the four patients with SD, and in the one patient with PD. Morphological imaging was predictive for PFS and OS when response was defined as CR, PR, SD, and non-response as PD. Metabolic imaging was predictive when using T/N ratio reduction of >25 as discriminator. Based on the morphologic and metabolic findings of this study a proposal for applying integrated PET/MRI for treatment response in relapsed GBM was developed, which was significantly predictive for PFS and OS (P = 0.010 respectively 0,029, log). This study demonstrates the potential of integrated 11C-MET-PET/MRI for response assessment of GBM and the utility of combined assessment of morphologic and metabolic information with the proposal for assessing relapsed GBM.

  19. Response assessment of bevacizumab therapy in GBM with integrated 11C-MET-PET/MRI: a feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Deuschl, Cornelius [University Hospital Essen, Institute of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); University of Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Duisburg (Germany); Moenninghoff, Christoph; Goericke, Sophia; Forsting, Michael; Umutlu, Lale [University Hospital Essen, Institute of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Kirchner, Julian [University Hospital Duesseldorf, Institute of Diagnostic and Interventional Radiology, Duesseldorf (Germany); Koeppen, Susanne [University Hospital Essen, Department of Neurology, Essen (Germany); Binse, Ina; Poeppel, Thorsten D.; Herrmann, Ken [University Hospital Essen, Department of Nuclear Medicine, Essen (Germany); Quick, Harald H. [University of Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Duisburg (Germany); University Hospital Essen, High Field and Hybrid MR Imaging, Essen (Germany); Hense, Joerg [University Hospital Essen, Department of Medical Oncology, West German Cancer Center, Essen (Germany); Schlamann, Marc [University Hospital Essen, Institute of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); University Hospital Giessen, Department of Neuroradiology, Essen (Germany)

    2017-08-15

    The objective of this study was to evaluate the potential of integrated 11C-MET PET/MR for response assessment of relapsed glioblastoma (GBM) receiving bevacizumab treatment. Eleven consecutive patients with relapsed GBM were enrolled for an integrated 11C-MET PET/MRI at baseline and at follow-up. Treatment response for MRI was evaluated according to Response Assessment in Neuro-oncology (RANO) criteria and integrated 11C-MET PET was assessed by the T/N ratio. MRI showed no patient with complete response (CR), six of 11 patients with PR, four of 11 patients with SD, and one of 11 patients with progressive disease (PD). PET revealed metabolic response in five of the six patients with partial response (PR) and in two of the four patients with stable disease (SD), whereas metabolic non-response was detected in one of the six patients with PR, in two of the four patients with SD, and in the one patient with PD. Morphological imaging was predictive for PFS and OS when response was defined as CR, PR, SD, and non-response as PD. Metabolic imaging was predictive when using T/N ratio reduction of >25 as discriminator. Based on the morphologic and metabolic findings of this study a proposal for applying integrated PET/MRI for treatment response in relapsed GBM was developed, which was significantly predictive for PFS and OS (P = 0.010 respectively 0,029, log). This study demonstrates the potential of integrated 11C-MET-PET/MRI for response assessment of GBM and the utility of combined assessment of morphologic and metabolic information with the proposal for assessing relapsed GBM. (orig.)

  20. Tauopathy PET and amyloid PET in the diagnosis of chronic traumatic encephalopathies: studies of a retired NFL player and of a man with FTD and a severe head injury.

    Science.gov (United States)

    Mitsis, E M; Riggio, S; Kostakoglu, L; Dickstein, D L; Machac, J; Delman, B; Goldstein, M; Jennings, D; D'Antonio, E; Martin, J; Naidich, T P; Aloysi, A; Fernandez, C; Seibyl, J; DeKosky, S T; Elder, G A; Marek, K; Gordon, W; Hof, P R; Sano, M; Gandy, S

    2014-09-16

    Single, severe traumatic brain injury (TBI) which elevates CNS amyloid, increases the risk of Alzheimer's disease (AD); while repetitive concussive and subconcussive events as observed in athletes and military personnel, may increase the risk of chronic traumatic encephalopathy (CTE). We describe two clinical cases, one with a history of multiple concussions during a career in the National Football League (NFL) and the second with frontotemporal dementia and a single, severe TBI. Both patients presented with cognitive decline and underwent [(18)F]-Florbetapir positron emission tomography (PET) imaging for amyloid plaques; the retired NFL player also underwent [(18)F]-T807 PET imaging, a new ligand binding to tau, the main constituent of neurofibrillary tangles (NFT). Case 1, the former NFL player, was 71 years old when he presented with memory impairment and a clinical profile highly similar to AD. [(18)F]-Florbetapir PET imaging was negative, essentially excluding AD as a diagnosis. CTE was suspected clinically, and [(18)F]-T807 PET imaging revealed striatal and nigral [(18)F]-T807 retention consistent with the presence of tauopathy. Case 2 was a 56-year-old man with personality changes and cognitive decline who had sustained a fall complicated by a subdural hematoma. At 1 year post injury, [(18)F]-Florbetapir PET imaging was negative for an AD pattern of amyloid accumulation in this subject. Focal [(18)F]-Florbetapir retention was noted at the site of impact. In case 1, amyloid imaging provided improved diagnostic accuracy where standard clinical and laboratory criteria were inadequate. In that same case, tau imaging with [(18)F]-T807 revealed a subcortical tauopathy that we interpret as a novel form of CTE with a distribution of tauopathy that mimics, to some extent, that of progressive supranuclear palsy (PSP), despite a clinical presentation of amnesia without any movement disorder complaints or signs. A key distinguishing feature is that our patient presented

  1. The preliminary study of the blood perfusion and ammonia metabolism of pituitary using dynamic 13N-NH3 PET imaging

    International Nuclear Information System (INIS)

    Zhang Xiangsong; Tang Anwu; Qiao Suixian; Chen Liguang; Luo Yaowu; Liu Bin; Xu Weiping

    2002-01-01

    Objective: To preliminarily study the blood perfusion and ammonia metabolism of pituitary using dynamic 13 N-NH 3 PET imaging. Methods: 13 N-NH 3 PET imaging was performed on 21 subjects without pituitary diseases, 6 of them underwent dynamic PET imaging, and 8 of them underwent brain MRI in addition to PET. PET images were registered with MRI. Results: The pituitary could be clearly seen in 13 N-NH 3 PET images, and being confirmed by PET/MRI image fusion. The size of pituitary was (1.07 +- 0.17) cm x (1.09 +- 0.15) cm x (1.14 +- 0.17) cm, the standard uptake value (SUV) was 3.84 +- 1.75, and the radioactivity ratio of pituitary to thalamus was 1.35 +- 0.63. Pituitary image was seen at 10 s after the internal carotid was seen in dynamic 13 N-NH 3 PET imaging. 13 N-NH 3 was retained in pituitary, and was hardly cleaned out within 20 min. The radioactivity ratio of pituitary to internal carotid was 0.75 +- 0.13 when the radioactivity of internal carotid was at its highest level. Conclusions: The blood flow and ammonia metabolism of pituitary can be observed with dynamic 13 N-NH 3 PET imaging. Ammonia is highly extracted by pituitary, and metabolized in pituitary cells

  2. Relative equilibrium plot improves graphical analysis and allows bias correction of SUVR in quantitative [11C]PiB PET studies

    OpenAIRE

    Zhou, Yun; Sojkova, Jitka; Resnick, Susan M.; Wong, Dean F.

    2012-01-01

    Both the standardized uptake value ratio (SUVR) and the Logan plot result in biased distribution volume ratios (DVR) in ligand-receptor dynamic PET studies. The objective of this study is to use a recently developed relative equilibrium-based graphical plot (RE plot) method to improve and simplify the two commonly used methods for quantification of [11C]PiB PET.

  3. Motion detection and correction for dynamic 15O-water myocardial perfusion PET studies

    International Nuclear Information System (INIS)

    Naum, Alexandru; Laaksonen, Marko S.; Oikonen, Vesa; Teraes, Mika; Jaervisalo, Mikko J.; Knuuti, Juhani; Tuunanen, Helena; Nuutila, Pirjo; Kemppainen, Jukka

    2005-01-01

    Patient motion during dynamic PET studies is a well-documented source of errors. The purpose of this study was to investigate the incidence of frame-to-frame motion in dynamic 15 O-water myocardial perfusion PET studies, to test the efficacy of motion correction methods and to study whether implementation of motion correction would have an impact on the perfusion results. We developed a motion detection procedure using external radioactive skin markers and frame-to-frame alignment. To evaluate motion, marker coordinates inside the field of view were determined in each frame for each study. The highest number of frames with identical spatial coordinates during the study were defined as ''non-moved''. Movement was considered present if even one marker changed position, by one pixel/frame compared with reference, in one axis, and such frames were defined as ''moved''. We tested manual, in-house-developed motion correction software and an automatic motion correction using a rigid body point model implemented in MIPAV (Medical Image Processing, Analysis and Visualisation) software. After motion correction, remaining motion was re-analysed. Myocardial blood flow (MBF) values were calculated for both non-corrected and motion-corrected datasets. At rest, patient motion was found in 18% of the frames, but during pharmacological stress the fraction increased to 45% and during physical exercise it rose to 80%. Both motion correction algorithms significantly decreased (p<0.006) the number of moved frames and the amplitude of motion (p<0.04). Motion correction significantly increased MBF results during bicycle exercise (p<0.02). At rest or during adenosine infusion, the motion correction had no significant effects on MBF values. Significant motion is a common phenomenon in dynamic cardiac studies during adenosine infusion but especially during exercise. Applying motion correction for the data acquired during exercise clearly changed the MBF results, indicating that motion

  4. 18F-Fluoroacetate - A longer lived acetate analogue for oncology studies with PET

    International Nuclear Information System (INIS)

    Khezami, Arbia; Ulrich, Eva; Matthies, Alexander; Ezziddin, Samer; Bender, Hans; Biersack, Hans-Juergen; Guhlke, Stefan

    2004-01-01

    Full text: Aim: 18 F-Fluoroacetate ( 18 Fac) can be considered as a fluoro analogue of 11C-acetate. Thus it may also be useful for oncologic PET studies. Like acetate, fluoroacetate is a substrate of the citric acid cycle, however in contrast to acetate it is an inhibitor of the enzyme Aconitase and thus no further metabolization of fluoroacetate occurs. The aim of this study was the in-vivo evaluation of this tracer with respect to tumor uptake in prostate carcinoma bearing nude mice as well as biodistribution and kinetics. Methods: The synthesis of 18 F-fluoroacetate was performed by using benzyl bromoacetate as precursor. The fluorinated ester was separated by HPLC, followed by basic hydrolysis and purification by use of anion exchange SEP-Pak chromatography. The formulation was performed by rinsing with water and subsequent elution of 18 Fac with sterile PBS-buffer and final sterile filtration. For the biodistribution studies, 3 groups of nude mice were inoculated with the prostate carcinoma cell lines PC3, DU-145 and LnCAP. After tumor growth, the animals were injected with 37-370 KBq of 18 Fac and bio-distributions performed at different times post injection. Results: The rcy of the substitution step was usually > 90%. The HPLC separation of the fluorinated ester and the precursor was performed on a C-18 column. The high UV-absorbance of the benzyl ester allows the determination of the specific activity of the tracer which was always lower than detection limits. Further, the injected animals did not show any signs of intoxication. The biodistribution studies revealed a primary biliary excretion. Regardless which cell line was used, accumulation of 18 Fac in tumor sites was well visible by PET-CT. Tumor to blood ratios increased with time. Conclusion: The synthesis of 18 Fac is straight forward and high radiochemical yields are typically obtained. The high specific activity of 18 F-fluoride allows injections of 18 Fac far below toxic concentrations. In nude

  5. Study on the characteristics of barrier free surface discharge driven by repetitive nanosecond pulses at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Pang; Qiaogen, Zhang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Kun, He [China Electric Power Research Institute, Beijing 100192 (China); Chunliang, Liu [State Key Laboratory for Physical Electronics and Devices, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-05-15

    Nanosecond pulsed plasma has an enormous potential in many applications. In this paper, the characteristics of barrier free nanosecond pulsed surface discharge are investigated by the use of an actuator with a strip-strip film electrode configuration, including the effect of electrode width and the gap distance on the plasma morphology and electrical characteristics at atmospheric pressure. It was found that it is relative easier to generate a quasi uniform discharge with a thinner electrode width and a smaller gap distance. The underlying physical mechanism was also discussed. Besides that, the influence of airflow on repetitive pulsed surface discharge was examined. By comparing to the discharge produced by two different pulse waveforms in airflows, we found that the discharge driven by a faster pulse behaves more stable. Finally, a model was developed to analyze the interaction of the airflow and the discharge channels.

  6. Regional differences in the CBF and BOLD responses to hypercapnia: a combined PET and fMRI study

    DEFF Research Database (Denmark)

    Rostrup, Egill; Law, I; Blinkenberg, M

    2000-01-01

    Previous fMRI studies of the cerebrovascular response to hypercapnia have shown signal change in cerebral gray matter, but not in white matter. Therefore, the objective of the present study was to compare (15)O PET and T *(2)-weighted MRI during a hypercapnic challenge. The measurements were perf...

  7. Gamma camera based FDG PET in oncology

    International Nuclear Information System (INIS)

    Park, C. H.

    2002-01-01

    Positron Emission Tomography(PET) was introduced as a research tool in the 1970s and it took about 20 years before PET became an useful clinical imaging modality. In the USA, insurance coverage for PET procedures in the 1990s was the turning point, I believe, for this progress. Initially PET was used in neurology but recently more than 80% of PET procedures are in oncological applications. I firmly believe, in the 21st century, one can not manage cancer patients properly without PET and PET is very important medical imaging modality in basic and clinical sciences. PET is grouped into 2 categories; conventional (c) and gamma camera based ( CB ) PET. CB PET is more readily available utilizing dual-head gamma cameras and commercially available FDG to many medical centers at low cost to patients. In fact there are more CB PET in operation than cPET in the USA. CB PET is inferior to cPET in its performance but clinical studies in oncology is feasible without expensive infrastructures such as staffing, rooms and equipments. At Ajou university Hospital, CBPET was installed in late 1997 for the first time in Korea as well as in Asia and the system has been used successfully and effectively in oncological applications. Our was the fourth PET operation in Korea and I believe this may have been instrumental for other institutions got interested in clinical PET. The following is a brief description of our clinical experience of FDG CBPET in oncology

  8. Altered glucose metabolism in juvenile myoclonic epilepsy: a PET study with statistical parametric mapping

    International Nuclear Information System (INIS)

    Lim, G. C.; Kim, J. H.; Kang, J. G.; Kim, J. S.; Yeo, J. S.; Lee, S. A.; Moon, D. H

    2004-01-01

    Juvenile myoclonic epilepsy (JME) is a hereditary, age-dependent epilepsy syndrome, characterized by myoclonic jerks on awakening and generalized tonic-clonic seizures. Although there have been considerable studies on the mechanism to elucidate pathogenesis of JME, the accurate pathogenesis of JME remains obscure. The aim of this study was to investigate alterations of cerebral glucose metabolism in patients with JME. We studied 16 JME patients (Mean age: 22 yrs, M/F: 9/7) with brain FDG-PET and simultaneous EEG recording. On the basis of the number of generalized spike-and-wave (GSW) discharges on the 30 min EEG recording after the injection of FDG (370MBq), we classified patients into two groups (patients in group A had 10 or more GSW and group B. 9 or less). We applied the automated and objective technique of statistical parametric mapping (SPM) to the analysis of FDG-PET to determine the significant hyper- and hypometabolic regions compared with those of 19 age matched normal control subjects. We found significant hypermetabolic regions in bilateral thalamus and central portion of upper brainstem in 16 patients with JME at a statistical threshold of uncorrected P < 0.05. These changes were also shown in group A (n=8), but not in group B (n=8). Additionally, we found significant hypometabolism in bilateral, widespread cortical regions in 16 patients with JME at a threshold of uncorrected P < 0.01. Similar hypometabolic patterns were also observed in both group A and group B, being more prominent in group A. This study provides evidence for the key role of the thalamus and brainstem reticular activating system in generating spontaneous GSW discharge, which is considered as a fundamental pathogenesis underlying JME. This study also suggests that patients with JME might suffer from subtle abnormalities of cognitive and executive cortical functions

  9. Fast synthesis of 11C-Raclopride and its initial PET study on animal model

    International Nuclear Information System (INIS)

    Zhang Jinming; Tian Jiahe; Yao Shulin; Ding Weimin; Yin Dayi; Liu Boli

    2008-01-01

    Objective: 11 C-Raclopride is a type-2 dopamine receptor (D 2 R) binding agent used in the study of Parkinson's disease. This study introduced a fast and convenient method for preparation of 11 C- Raclopride and reported on the preclinical trial of this receptor tracer on animal studies. Methods: 11 C- Raclopride was synthesized via reaction of 11 C-CH 3 -Triflate with Nor-Raclopride. The mixture of primary product was water-diluted and loaded on Sep-Pak C18 column for separation. The final product, 11 C-Raclopride, was purified by column chromatography and then eluted from the C18 column with ethanol. The bio-distribution was studied in SD rats and the in vivo imaging pattern was studied in hem ipark insonjan mon- keys. Results: Within 16 min from beginning of processing with 11 CO 2 , the synthetic yield of 11 C-Raclopride was 60%, radiochemical purity (RCP) > 95% and specific activity 8 GBq/mmol. The uptake ratios of striatum to cerebellum and cerebral cortex were 4.67 and 6.20, respectively, at 30 min after 11 C-Raclopride administration. The striatal uptake in normal rat brain could be blocked by N-methylspiperone (NMSP) and raclopride, but not by Nor-raclopride. PET imaging showed higher striatal D 2 R uptake on the D 2 receptor up-regulated side of the experimental monkeys relative to the contralateral side. Conclusions: Column chromatography for purification of 11 C-Raclopride was fast, convenient and with a RCP similar to that of high performance liquid chromatography purification. Preliminary PET findings using animal model suggested that 11 C-Raclopride by column chromatogram purification might be considered for clinical use. (authors)

  10. Altered glucose metabolism in juvenile myoclonic epilepsy: a PET study with statistical parametric mapping

    Energy Technology Data Exchange (ETDEWEB)

    Lim, G. C.; Kim, J. H.; Kang, J. G.; Kim, J. S.; Yeo, J. S.; Lee, S. A.; Moon, D. H [Asan Medical Center, Seoul (Korea, Republic of)

    2004-07-01

    Juvenile myoclonic epilepsy (JME) is a hereditary, age-dependent epilepsy syndrome, characterized by myoclonic jerks on awakening and generalized tonic-clonic seizures. Although there have been considerable studies on the mechanism to elucidate pathogenesis of JME, the accurate pathogenesis of JME remains obscure. The aim of this study was to investigate alterations of cerebral glucose metabolism in patients with JME. We studied 16 JME patients (Mean age: 22 yrs, M/F: 9/7) with brain FDG-PET and simultaneous EEG recording. On the basis of the number of generalized spike-and-wave (GSW) discharges on the 30 min EEG recording after the injection of FDG (370MBq), we classified patients into two groups (patients in group A had 10 or more GSW and group B. 9 or less). We applied the automated and objective technique of statistical parametric mapping (SPM) to the analysis of FDG-PET to determine the significant hyper- and hypometabolic regions compared with those of 19 age matched normal control subjects. We found significant hypermetabolic regions in bilateral thalamus and central portion of upper brainstem in 16 patients with JME at a statistical threshold of uncorrected P < 0.05. These changes were also shown in group A (n=8), but not in group B (n=8). Additionally, we found significant hypometabolism in bilateral, widespread cortical regions in 16 patients with JME at a threshold of uncorrected P < 0.01. Similar hypometabolic patterns were also observed in both group A and group B, being more prominent in group A. This study provides evidence for the key role of the thalamus and brainstem reticular activating system in generating spontaneous GSW discharge, which is considered as a fundamental pathogenesis underlying JME. This study also suggests that patients with JME might suffer from subtle abnormalities of cognitive and executive cortical functions.

  11. Artefactual subcortical hyperperfusion in PET studies normalized to global mean: lessons from Parkinson's disease

    DEFF Research Database (Denmark)

    Borghammer, Per; Cumming, Paul; Aanerud, Joel

    2008-01-01

    not be detected with present instrumentation and typically-used sample sizes. CONCLUSION: Imposing focal decreases on cortical CBF in conjunction with global mean normalization gives rise to spurious relative CBF increases in all of the regions reported to be hyperactive in PD. Since no PET study has reported......AIM: Recent studies of Parkinson's disease (PD) report subcortical increases of cerebral blood flow (CBF) or cerebral metabolic rate of glucose (CMRglc), after conventional normalization to the global mean. However, if the global mean CBF or CMRglc is decreased in the PD group, this normalization...... necessarily generates artificial relative increases in regions unaffected by the disease. This potential bias may explain the reported subcortical increases in PD. To test this hypothesis, we performed simulations with manipulation and subsequently analysis of sets of quantitative CBF maps by voxel...

  12. How to study optimal timing of PET/CT for monitoring of cancer treatment

    DEFF Research Database (Denmark)

    Vach, Werner; Høilund-Carlsen, Poul Flemming; Fischer, Barbara Malene Bjerregaard

    2011-01-01

    Purpose: The use of PET/CT for monitoring treatment response in cancer patients after chemo- or radiotherapy is a very promising approach to optimize cancer treatment. However, the timing of the PET/CT-based evaluation of reduction in viable tumor tissue is a crucial question. We investigated how...

  13. Preclinical Study on GRPR-Targeted (68)Ga-Probes for PET Imaging of Prostate Cancer

    DEFF Research Database (Denmark)

    Sun, Yao; Ma, Xiaowei; Zhang, Zhe

    2016-01-01

    Gastrin-releasing peptide receptor (GRPR) targeted positron emission tomography (PET) is a highly promising approach for imaging of prostate cancer (PCa) in small animal models and patients. Developing a GRPR-targeted PET probe with excellent in vivo performance such as high tumor uptake, high...

  14. In-beam PET at high-energy photon beams: a feasibility study

    Science.gov (United States)

    Müller, H.; Enghardt, W.

    2006-04-01

    For radiation therapy with carbon ion beams, either for the stable isotope 12C or for the radioactive one 11C, it has been demonstrated that the β+-activity distribution created or deposited, respectively, within the irradiated volume can be visualized by means of positron emission tomography (PET). The PET images provide valuable information for quality assurance and precision improvement of ion therapy. Dedicated PET scanners have been integrated into treatment sites at the Heavy Ion Medical Accelerator at Chiba (HIMAC), Japan, and the Gesellschaft für Schwerionenforschung (GSI), Germany, to make PET imaging feasible during therapeutic irradiation (in-beam PET). A similar technique may be worthwhile for radiotherapy with high-energy bremsstrahlung. In addition to monitoring the dose delivery process which in-beam PET has been primarily developed for, it may be expected that radiation response of tissue can be detected by means of in-beam PET. We investigate the applicability of PET for treatment control in the case of using bremsstrahlung spectra produced by 15-50 MeV electrons. Target volume activation due to (γ, n) reactions at energies above 20 MeV yields moderate β+-activity levels, which can be employed for imaging. The radiation from positrons produced by pair production is not presently usable because the detectors are overloaded due to the low duty factor of medical electron linear accelerators. However, the degradation of images caused by positron motion between creation and annihilation seems to be tolerable.

  15. First in situ TOF-PET study using digital photon counters for proton range verification

    NARCIS (Netherlands)

    Cambraia Lopes Ferreira da Silva, P.; Bauer, J.; Salomon, A.; Rinaldi, I; Tabacchini, V.; Tessonnier, T.; Crespo, P; Parodi, K; Schaart, D.R.

    2016-01-01

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong 15O signal due to its relatively short half-life (∼2 min) and high

  16. Monte Carlo simulation tool for online treatment monitoring in hadrontherapy with in-beam PET: A patient study.

    Science.gov (United States)

    Fiorina, E; Ferrero, V; Pennazio, F; Baroni, G; Battistoni, G; Belcari, N; Cerello, P; Camarlinghi, N; Ciocca, M; Del Guerra, A; Donetti, M; Ferrari, A; Giordanengo, S; Giraudo, G; Mairani, A; Morrocchi, M; Peroni, C; Rivetti, A; Da Rocha Rolo, M D; Rossi, S; Rosso, V; Sala, P; Sportelli, G; Tampellini, S; Valvo, F; Wheadon, R; Bisogni, M G

    2018-05-07

    Hadrontherapy is a method for treating cancer with very targeted dose distributions and enhanced radiobiological effects. To fully exploit these advantages, in vivo range monitoring systems are required. These devices measure, preferably during the treatment, the secondary radiation generated by the beam-tissue interactions. However, since correlation of the secondary radiation distribution with the dose is not straightforward, Monte Carlo (MC) simulations are very important for treatment quality assessment. The INSIDE project constructed an in-beam PET scanner to detect signals generated by the positron-emitting isotopes resulting from projectile-target fragmentation. In addition, a FLUKA-based simulation tool was developed to predict the corresponding reference PET images using a detailed scanner model. The INSIDE in-beam PET was used to monitor two consecutive proton treatment sessions on a patient at the Italian Center for Oncological Hadrontherapy (CNAO). The reconstructed PET images were updated every 10 s providing a near real-time quality assessment. By half-way through the treatment, the statistics of the measured PET images were already significant enough to be compared with the simulations with average differences in the activity range less than 2.5 mm along the beam direction. Without taking into account any preferential direction, differences within 1 mm were found. In this paper, the INSIDE MC simulation tool is described and the results of the first in vivo agreement evaluation are reported. These results have justified a clinical trial, in which the MC simulation tool will be used on a daily basis to study the compliance tolerances between the measured and simulated PET images. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. [18F]-FMISO PET study of hypoxia in gliomas before surgery: correlation with molecular markers of hypoxia and angiogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Bekaert, Lien [CHU de Caen, Department of Neurology, Caen (France); Normandie Univ, UNICAEN, CEA, CNRS, ISTCT/CERVOxy Group, Caen (France); CHU de Caen, Department of Neurosurgery, Caen (France); CHU de Caen, Service de Neurochirurgie, Caen (France); Valable, Samuel; Collet, Solene; Bordji, Karim; Petit, Edwige; Bernaudin, Myriam [Normandie Univ, UNICAEN, CEA, CNRS, ISTCT/CERVOxy Group, Caen (France); Lechapt-Zalcman, Emmanuele [Normandie Univ, UNICAEN, CEA, CNRS, ISTCT/CERVOxy Group, Caen (France); CHU de Caen, Department of Pathology, Caen (France); Ponte, Keven [CHU de Caen, Department of Neurosurgery, Caen (France); Normandie Univ, UNICAEN, CEA, CNRS, ISTCT/CERVOxy Group, Caen (France); Constans, Jean-Marc [Normandie Univ, UNICAEN, CEA, CNRS, ISTCT/CERVOxy Group, Caen (France); CHU de Caen, Department of Neuroradiology, Caen (France); Levallet, Guenaelle [CHU de Caen, Department of Pathology, Caen (France); Branger, Pierre [CHU de Caen, Department of Neurology, Caen (France); Emery, Evelyne [CHU de Caen, Department of Neurosurgery, Caen (France); Manrique, Alain [CHU de Caen, Department of Nuclear Medicine, Caen (France); Barre, Louisa [Normandie Univ, UNICAEN, CEA, CNRS, ISTCT/LDM-TEP group, Caen (France); Guillamo, Jean-Sebastien [CHU de Caen, Department of Neurology, Caen (France); Normandie Univ, UNICAEN, CEA, CNRS, ISTCT/CERVOxy Group, Caen (France); CHU de Nimes, Department of Neurology, Nimes (France)

    2017-08-15

    Hypoxia in gliomas is associated with tumor resistance to radio- and chemotherapy. However, positron emission tomography (PET) imaging of hypoxia remains challenging, and the validation of biological markers is, therefore, of great importance. We investigated the relationship between uptake of the PET hypoxia tracer [18F]-FMISO and other markers of hypoxia and angiogenesis and with patient survival. In this prospective single center clinical study, 33 glioma patients (grade IV: n = 24, III: n = 3, and II: n = 6) underwent [18F]-FMISO PET and MRI including relative cerebral blood volume (rCBV) maps before surgery. Maximum standardized uptake values (SUVmax) and hypoxic volume were calculated, defining two groups of patients based on the presence or absence of [18F]-FMISO uptake. After surgery, molecular quantification of CAIX, VEGF, Ang2 (rt-qPCR), and HIF-1α (immunohistochemistry) were performed on tumor specimens. [18F]-FMISO PET uptake was closely linked to tumor grade, with high uptake in glioblastomas (GB, grade IV). Expression of biomarkers of hypoxia (CAIX, HIF-1α), and angiogenesis markers (VEGF, Ang2, rCBV) were significantly higher in the [18F]-FMISO uptake group. We found correlations between the degree of hypoxia (hypoxic volume and SUVmax) and expression of HIF-1α, CAIX, VEGF, Ang2, and rCBV (p < 0.01). Patients without [18F]-FMISO uptake had a longer survival time than uptake positive patients (log-rank, p < 0.005). Tumor hypoxia as evaluated by [18F]-FMISO PET is associated with the expression of hypoxia markers on a molecular level and is related to angiogenesis. [18F]-FMISO uptake is a mark of an aggressive tumor, almost always a glioblastoma. Our results underline that [18F]-FMISO PET could be useful to guide glioma treatment, and in particular radiotherapy, since hypoxia is a well-known factor of resistance. (orig.)

  18. Correction for FDG PET dose extravasations: Monte Carlo validation and quantitative evaluation of patient studies

    Energy Technology Data Exchange (ETDEWEB)

    Silva-Rodríguez, Jesús, E-mail: jesus.silva.rodriguez@sergas.es; Aguiar, Pablo, E-mail: pablo.aguiar.fernandez@sergas.es [Fundación Ramón Domínguez, Santiago de Compostela, Galicia (Spain); Servicio de Medicina Nuclear, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Sánchez, Manuel; Mosquera, Javier; Luna-Vega, Víctor [Servicio de Radiofísica y Protección Radiológica, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Cortés, Julia; Garrido, Miguel [Servicio de Medicina Nuclear, Complexo Hospitalario Universitario de Santiago de Compostela, 15706, Galicia, Spain and Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Pombar, Miguel [Servicio de Radiofísica y Protección Radiológica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706, Galicia (Spain); Ruibal, Álvaro [Servicio de Medicina Nuclear, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Fundación Tejerina, 28003, Madrid (Spain)

    2014-05-15

    Purpose: Current procedure guidelines for whole body [18F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) state that studies with visible dose extravasations should be rejected for quantification protocols. Our work is focused on the development and validation of methods for estimating extravasated doses in order to correct standard uptake value (SUV) values for this effect in clinical routine. Methods: One thousand three hundred sixty-seven consecutive whole body FDG-PET studies were visually inspected looking for extravasation cases. Two methods for estimating the extravasated dose were proposed and validated in different scenarios using Monte Carlo simulations. All visible extravasations were retrospectively evaluated using a manual ROI based method. In addition, the 50 patients with higher extravasated doses were also evaluated using a threshold-based method. Results: Simulation studies showed that the proposed methods for estimating extravasated doses allow us to compensate the impact of extravasations on SUV values with an error below 5%. The quantitative evaluation of patient studies revealed that paravenous injection is a relatively frequent effect (18%) with a small fraction of patients presenting considerable extravasations ranging from 1% to a maximum of 22% of the injected dose. A criterion based on the extravasated volume and maximum concentration was established in order to identify this fraction of patients that might be corrected for paravenous injection effect. Conclusions: The authors propose the use of a manual ROI based method for estimating the effectively administered FDG dose and then correct SUV quantification in those patients fulfilling the proposed criterion.

  19. Gender differences in cerebral metabolism for color processing in mice: A PET/MRI Study.

    Science.gov (United States)

    Njemanze, Philip C; Kranz, Mathias; Amend, Mario; Hauser, Jens; Wehrl, Hans; Brust, Peter

    2017-01-01

    Color processing is a central component of mammalian vision. Gender-related differences of color processing revealed by non-invasive functional transcranial Doppler ultrasound suggested right hemisphere pattern for blue/yellow chromatic opponency by men, and a left hemisphere pattern by women. The present study measured the accumulation of [18F]fluorodeoxyglucose ([18F]FDG) in mouse brain using small animal positron emission tomography and magnetic resonance imaging (PET/MRI) with statistical parametric mapping (SPM) during light stimulation with blue and yellow filters compared to darkness condition. PET revealed a reverse pattern relative to dark condition compared to previous human studies: Male mice presented with left visual cortex dominance for blue through the right eye, while female mice presented with right visual cortex dominance for blue through the left eye. We applied statistical parametric mapping (SPM) to examine gender differences in activated architectonic areas within the orbital and medial prefrontal cortex and related cortical and sub-cortical areas that lead to the striatum, medial thalamus and other brain areas. The metabolic connectivity of the orbital and medial prefrontal cortex evoked by blue stimulation spread through a wide range of brain structures implicated in viscerosensory and visceromotor systems in the left intra-hemispheric regions in male, but in the right-to-left inter-hemispheric regions in female mice. Color functional ocular dominance plasticity was noted in the right eye in male mice but in the left eye in female mice. This study of color processing in an animal model could be applied in the study of the role of gender differences in brain disease.

  20. Minimally invasive input function for 2-{sup 18}F-fluoro-A-85380 brain PET studies

    Energy Technology Data Exchange (ETDEWEB)

    Zanotti-Fregonara, Paolo [National Institute of Mental Health, NIH, Molecular Imaging Branch, Bethesda, MD (United States); Maroy, Renaud; Peyronneau, Marie-Anne; Trebossen, Regine [CEA, DSV, I2BM, Service Hospitalier Frederic Joliot, Orsay (France); Bottlaender, Michel [CEA, DSV, I2BM, NeuroSpin, Gif-sur-Yvette (France)

    2012-04-15

    Quantitative neuroreceptor positron emission tomography (PET) studies often require arterial cannulation to measure input function. While population-based input function (PBIF) would be a less invasive alternative, it has only rarely been used in conjunction with neuroreceptor PET tracers. The aims of this study were (1) to validate the use of PBIF for 2-{sup 18}F-fluoro-A-85380, a tracer for nicotinic receptors; (2) to compare the accuracy of measures obtained via PBIF to those obtained via blood-scaled image-derived input function (IDIF) from carotid arteries; and (3) to explore the possibility of using venous instead of arterial samples for both PBIF and IDIF. Ten healthy volunteers underwent a dynamic 2-{sup 18}F-fluoro-A-85380 brain PET scan with arterial and, in seven subjects, concurrent venous serial blood sampling. PBIF was obtained by averaging the normalized metabolite-corrected arterial input function and subsequently scaling each curve with individual blood samples. IDIF was obtained from the carotid arteries using a blood-scaling method. Estimated Logan distribution volume (V{sub T}) values were compared to the reference values obtained from arterial cannulation. For all subjects, PBIF curves scaled with arterial samples were similar in shape and magnitude to the reference arterial input function. The Logan V{sub T} ratio was 1.00 {+-} 0.05; all subjects had an estimation error <10%. IDIF gave slightly less accurate results (V{sub T} ratio 1.03 {+-} 0.07; eight of ten subjects had an error <10%). PBIF scaled with venous samples yielded inaccurate results (V{sub T} ratio 1.13 {+-} 0.13; only three of seven subjects had an error <10%). Due to arteriovenous differences at early time points, IDIF could not be calculated using venous samples. PBIF scaled with arterial samples accurately estimates Logan V{sub T} for 2-{sup 18}F-fluoro-A-85380. Results obtained with PBIF were slightly better than those obtained with IDIF. Due to arteriovenous concentration

  1. Synthesis and PET studies of [(11)C-cyano]letrozole (Femara), an aromatase inhibitor drug.

    Science.gov (United States)

    Kil, Kun-Eek; Biegon, Anat; Ding, Yu-Shin; Fischer, Andre; Ferrieri, Richard A; Kim, Sung Won; Pareto, Deborah; Schueller, Michael J; Fowler, Joanna S

    2009-02-01

    Aromatase, a member of the cytochrome P450 family, converts androgens such as androstenedione and testosterone into estrone and estradiol, respectively. Letrozole (1-[bis-(4-cyanophenyl)methyl]-1H-1,2,4-triazole; Femara) is a high-affinity aromatase inhibitor (K(i)=11.5 nM) that has Food and Drug Administration approval for breast cancer treatment. Here we report the synthesis of carbon-11-labeled letrozole and its assessment as a radiotracer for brain aromatase in the baboon. Letrozole and its precursor (4-[(4-bromophenyl)-1H-1,2,4-triazol-1-ylmethyl]benzonitrile) were prepared in a two-step synthesis from 4-cyanobenzyl bromide and 4-bromobenzyl bromide, respectively. The [(11)C]cyano group was introduced via tetrakis(triphenylphosphine)palladium(0)-catalyzed coupling of [(11)C]cyanide with the bromo precursor. Positron emission tomography (PET) studies in the baboon brain were carried out to assess regional distribution and kinetics, reproducibility of repeated measures and saturability. Log D, the free fraction of letrozole in plasma and the [(11)C-cyano]letrozole fraction in arterial plasma were also measured. [(11)C-cyano]Letrozole was synthesized in 60 min with a radiochemical yield of 79-80%, with a radiochemical purity greater than 98% and a specific activity of 4.16+/-2.21 Ci/mumol at the end of bombardment (n=4). PET studies in the baboon revealed initial rapid and high uptake and initial rapid clearance, followed by slow clearance of carbon-11 from the brain, with no difference between brain regions. Brain kinetics was not affected by coinjection of unlabeled letrozole (0.1 mg/kg). The free fraction of letrozole in plasma was 48.9%, and log D was 1.84. [(11)C-cyano]Letrozole is readily synthesized via a palladium-catalyzed coupling reaction with [(11)C]cyanide. Although it is unsuitable as a PET radiotracer for brain aromatase, as revealed by the absence of regional specificity and saturability in brain regions such as amygdala, which are known to

  2. Synthesis and PET studies of [{sup 11}C-cyano]letrozole (Femara), an aromatase inhibitor drug

    Energy Technology Data Exchange (ETDEWEB)

    Kil, Kun-Eek [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Department of Chemistry, Stony Brook University, Stony Brook, NY 11794 (United States); Biegon, Anat [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Ding, Yu-Shin [Department of Radiology, Yale University School of Medicine, New Haven, CT 06520-8048 (United States); Fischer, Andre [Johannes-Gutenberg Universitaet Mainz, Institut fuer Organische Chemie, 55128 Mainz (Germany); Ferrieri, Richard A.; Kim, Sung Won; Pareto, Deborah; Schueller, Michael J. [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Fowler, Joanna S. [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Department of Chemistry, Stony Brook University, Stony Brook, NY 11794 (United States)], E-mail: fowler@bnl.gov

    2009-02-15

    Introduction: Aromatase, a member of the cytochrome P450 family, converts androgens such as androstenedione and testosterone into estrone and estradiol, respectively. Letrozole (1-[bis-(4-cyanophenyl)methyl]-1H-1,2,4-triazole; Femara) is a high-affinity aromatase inhibitor (K{sub i}=11.5 nM) that has Food and Drug Administration approval for breast cancer treatment. Here we report the synthesis of carbon-11-labeled letrozole and its assessment as a radiotracer for brain aromatase in the baboon. Methods: Letrozole and its precursor (4-[(4-bromophenyl)-1H-1,2,4-triazol-1-ylmethyl]benzonitrile) were prepared in a two-step synthesis from 4-cyanobenzyl bromide and 4-bromobenzyl bromide, respectively. The [{sup 11}C]cyano group was introduced via tetrakis(triphenylphosphine)palladium(0)-catalyzed coupling of [{sup 11}C]cyanide with the bromo precursor. Positron emission tomography (PET) studies in the baboon brain were carried out to assess regional distribution and kinetics, reproducibility of repeated measures and saturability. Log D, the free fraction of letrozole in plasma and the [{sup 11}C-cyano]letrozole fraction in arterial plasma were also measured. Results: [{sup 11}C-cyano]Letrozole was synthesized in 60 min with a radiochemical yield of 79-80%, with a radiochemical purity greater than 98% and a specific activity of 4.16{+-}2.21 Ci/{mu}mol at the end of bombardment (n=4). PET studies in the baboon revealed initial rapid and high uptake and initial rapid clearance, followed by slow clearance of carbon-11 from the brain, with no difference between brain regions. Brain kinetics was not affected by coinjection of unlabeled letrozole (0.1 mg/kg). The free fraction of letrozole in plasma was 48.9%, and log D was 1.84. Conclusion: [{sup 11}C-cyano]Letrozole is readily synthesized via a palladium-catalyzed coupling reaction with [{sup 11}C]cyanide. Although it is unsuitable as a PET radiotracer for brain aromatase, as revealed by the absence of regional specificity

  3. Investigation of the optimal detector arrangement for the helmet-chin PET – A simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Abdella M., E-mail: abdellanur@gmail.com; Tashima, Hideaki; Yoshida, Eiji; Yamaya, Taiga, E-mail: yamaya.taiga@qst.go.jp

    2017-06-21

    High sensitivity and high spatial resolution dedicated brain PET scanners are in high demand for early diagnosis of neurodegenerative diseases and studies of brain functions. To meet the demand, we have proposed the helmet-chin PET geometry which has a helmet detector and a chin detector. Our first prototype scanner used 54 4-layer depth-of-interaction (DOI) detectors. The helmet detector of the scanner had three detector rings with different radii arranged on a surface of a hemisphere (with a radius of 126.5 mm) and a top cover detector. Therefore, in this study, for our next development, we propose a spherical arrangement, in which the central axis of each detector points toward the center of the hemisphere, and we optimize the size of the detector crystal block to be arranged on the helmet detector. We simulate the spherical arrangement with the optimized crystal block size and compare its imaging performance with the multi-ring arrangement, which has a similar detector arrangement to that of our first prototype. We conduct Monte Carlo simulation to model the scanners having the 4-layer DOI detectors which consist of LYSO crystals. A dead space of 2 mm is assumed on each side of the crystal blocks such as for wrapping. The size of the crystal block is varied from 4×4 mm{sup 2} to 54×54 mm{sup 2} while fixing the thickness of the crystal block to 20 mm. We find that the crystal block sized at 42×42 mm{sup 2} has the highest sensitivity for a hemispherical phantom. The comparison of the two arrangements with the optimized crystal blocks show that, for the same number of crystal blocks, the spherical arrangement has 17% higher sensitivity for the hemispherical phantom than the multi-ring arrangement. We conclude that the helmet-chin PET with the spherical arrangement constructed from the crystal block sized at 42×42×20 mm{sup 3} has better imaging performance especially at the upper part of the brain compared to the multi-ring arrangement while keeping similar

  4. 3D Surface Realignment Tracking for Medical Imaging: A Phantom Study with PET Motion Correction

    DEFF Research Database (Denmark)

    Olesen, Oline Vinter; Paulsen, Rasmus Reinhold; Jensen, Rasmus Ramsbøl

    2011-01-01

    We present a complete system for motion correction in high resolution brain positron emission tomography (PET) imaging. It is based on a compact structured light scanner mounted above the patient tunnel of the Siemens High Resolution Research Tomograph PET brain scanner. The structured light system...... is equipped with a near infrared diode and uses phase-shift interferometry to compute 3D representations of the forehead of the patient. These 3D point clouds are progressively aligned to a reference surface and thereby giving the head pose changes. The estimated pose changes are used to reposition a sequence...... of recon- structed PET frames. To align the structured light system with the PET coordinate system a novel registration algorithm based on the PET trans- mission scan and an initial surface has been developed. The performance of the complete setup has been evaluated using a custom made phantom based...

  5. Modeling and analysis of PET studies with norepinephrine transporter ligands: the search for a reference region

    Energy Technology Data Exchange (ETDEWEB)

    Logan, Jean [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)]. E-mail: logan@bnl.gov; Ding, Y.-S. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Lin, K.-S. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Pareto, Deborah [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Functional Imaging, Berkeley National Laboratory, Berkeley, CA 94720 (United States); Fowler, Joanna [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Biegon, Anat [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2005-07-01

    The development of positron emission tomography (PET) ligands for the norepinephrine transporter (NET) has been slow compared to the development of radiotracers for others systems, such as the dopamine (DAT) or the serotonin transporters (SERT). The main reason for this appears to be the high nonspecific (non-NET) binding exhibited by many of these tracers, which makes the identification of a reference region difficult. With other PET ligands the use of a reference region increases the reproducibility of the outcome measure in test/retest studies. The focus of this work is to identify a suitable reference region or means of normalizing data for the NET ligands investigated. Methods: We have analyzed the results of PET studies in the baboon brain with labeled reboxetine derivatives (S,S)-[{sup 11}C]O-methyl reboxetine (SS-MRB), (S,S)-[{sup 18}F]fluororeboxetine (SS-FRB) as well as O-[{sup 11}C]nisoxetine and N-[{sup 11}C]nisoxetine (NIS), and, for comparison, the less active (R,R) enantiomers (RR-MRB, RR-FRB) in terms of the distribution volume (DV) using measured arterial input functions. Results: (1) For a given subject, a large variation in DV for successive baseline studies was observed in regions with both high and low NET density. (2) The occipital cortex and the basal ganglia were found to be the regions with the smallest change between baseline (SS-MRB) and pretreatment with cocaine, and were therefore used as a composite reference region for calculation of a distribution volume ratio (DVR). (3) The variability [as measured by the coefficient of variation (CV)=standard deviation/mean] in the distribution volume ratio (DVR) of thalamus (to reference region) was considerably reduced over that of the DV using this composite reference region. (4) Pretreatment with nisoxetine (1.0 mg/kg 10 min prior to tracer) in one study produced (in decreasing order) reductions in thalamus, cerebellum, cingulate and frontal cortex consistent with known NET densities. (5) [{sup

  6. Modeling and analysis of PET studies with norepinephrine transporter ligands: the search for a reference region.

    Science.gov (United States)

    Logan, Jean; Ding, Yu-Shin; Lin, Kuo-Shyan; Pareto, Deborah; Fowler, Joanna; Biegon, Anat

    2005-07-01

    The development of positron emission tomography (PET) ligands for the norepinephrine transporter (NET) has been slow compared to the development of radiotracers for others systems, such as the dopamine (DAT) or the serotonin transporters (SERT). The main reason for this appears to be the high nonspecific (non-NET) binding exhibited by many of these tracers, which makes the identification of a reference region difficult. With other PET ligands the use of a reference region increases the reproducibility of the outcome measure in test/retest studies. The focus of this work is to identify a suitable reference region or means of normalizing data for the NET ligands investigated. We have analyzed the results of PET studies in the baboon brain with labeled reboxetine derivatives (S,S)-[(11)C]O-methyl reboxetine (SS-MRB), (S,S)-[(18)F]fluororeboxetine (SS-FRB) as well as O-[(11)C]nisoxetine and N-[(11)C]nisoxetine (NIS), and, for comparison, the less active (R,R) enantiomers (RR-MRB, RR-FRB) in terms of the distribution volume (DV) using measured arterial input functions. (1) For a given subject, a large variation in DV for successive baseline studies was observed in regions with both high and low NET density. (2) The occipital cortex and the basal ganglia were found to be the regions with the smallest change between baseline (SS-MRB) and pretreatment with cocaine, and were therefore used as a composite reference region for calculation of a distribution volume ratio (DVR). (3) The variability [as measured by the coefficient of variation (CV) = standard deviation/mean] in the distribution volume ratio (DVR) of thalamus (to reference region) was considerably reduced over that of the DV using this composite reference region. (4) Pretreatment with nisoxetine (1.0 mg/kg 10 min prior to tracer) in one study produced (in decreasing order) reductions in thalamus, cerebellum, cingulate and frontal cortex consistent with known NET densities. (5) [(11)C]Nisoxetine had a higher

  7. Modeling and analysis of PET studies with norepinephrine transporter ligands: the search for a reference region

    International Nuclear Information System (INIS)

    Logan, Jean; Ding, Y.-S.; Lin, K.-S.; Pareto, Deborah; Fowler, Joanna; Biegon, Anat

    2005-01-01

    The development of positron emission tomography (PET) ligands for the norepinephrine transporter (NET) has been slow compared to the development of radiotracers for others systems, such as the dopamine (DAT) or the serotonin transporters (SERT). The main reason for this appears to be the high nonspecific (non-NET) binding exhibited by many of these tracers, which makes the identification of a reference region difficult. With other PET ligands the use of a reference region increases the reproducibility of the outcome measure in test/retest studies. The focus of this work is to identify a suitable reference region or means of normalizing data for the NET ligands investigated. Methods: We have analyzed the results of PET studies in the baboon brain with labeled reboxetine derivatives (S,S)-[ 11 C]O-methyl reboxetine (SS-MRB), (S,S)-[ 18 F]fluororeboxetine (SS-FRB) as well as O-[ 11 C]nisoxetine and N-[ 11 C]nisoxetine (NIS), and, for comparison, the less active (R,R) enantiomers (RR-MRB, RR-FRB) in terms of the distribution volume (DV) using measured arterial input functions. Results: (1) For a given subject, a large variation in DV for successive baseline studies was observed in regions with both high and low NET density. (2) The occipital cortex and the basal ganglia were found to be the regions with the smallest change between baseline (SS-MRB) and pretreatment with cocaine, and were therefore used as a composite reference region for calculation of a distribution volume ratio (DVR). (3) The variability [as measured by the coefficient of variation (CV)=standard deviation/mean] in the distribution volume ratio (DVR) of thalamus (to reference region) was considerably reduced over that of the DV using this composite reference region. (4) Pretreatment with nisoxetine (1.0 mg/kg 10 min prior to tracer) in one study produced (in decreasing order) reductions in thalamus, cerebellum, cingulate and frontal cortex consistent with known NET densities. (5) [ 11 C]Nisoxetine had

  8. Contribution of whole body F-18-FDG-PET and lymphoscintigraphy to the assessment of regional and distant metastases in cutaneous malignant melanoma. A pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Klein, M.; Freedman, N.; Marciano, R.; Moshe, S.; Chisin, R. [Hadassah Univ. Hospital, Jerusalem (Israel). Dept. of Medical Biophysics and Nuclear Medicine; Lotem, M. [Hadassah Univ. Hospital, Jerusalem (Israel). Dept. of Oncology; Gimon, Z. [Hadassah Univ. Hospital, Jerusalem (Israel). Dept. of Surgery

    2000-05-01

    Aim: This pilot study describes use of whole body PET (WB PET) for staging of melanoma. WB PET in conjunction with lymphoscintigraphy (LS) for evaluating status of the sentinel lymph node (SLN) in primary melanoma was investigated with comparison to histopathological results. WB PET was also used both for primary and metastatic melanoma for screening for distant metastases, restaging and follow-up. Methods: Group I: 17 patients with primary cutaneous melanoma underwent LS, WB PET and SLN dissection. WB PET findings were compared with biopsy results at the SLN site and were used for screening for distant metastases. Group II: 17 patients with a history of melanoma underwent WB PET for follow-up and/or restaging. Results were confirmed or refuted by other radiological modalities or by biopsy of clinical follow-up. Results: Group I: Out of 20 SLNs identified by LS in the 17 patients, 18 were negative on WB PET and 2 were positive. 19/20 WB PET findings were confirmed either by histopathology or by clinical follow-up (20 mo). Accuracy was 94% for the assessment of the status of the SLN. Group II: WB PET findings altered staging and treatment in 12/17 patients and confirmed the validity of treatment in 3/17 patients. Overall, in 15/17 patients (88%), WB PET had an impact on treatment strategy. (orig.) [German] Ziel: Diese Pilot-Studie beschreibt die Anwendung der Ganzkoerper-PET (WB PET) zum Staging beim Melanom. Bei primaerem Melanom wurde WB PET in Verbindung mit der Lymphszintigraphie (LS) angewandt und mit der Histopathologie verglichen, um den Status des Sentinel Lymph Node (SLN) zu untersuchen. Zusaetzlich wurde WB PET fuer primaere und metastatische Melanome zum Screening auf Fernmetastasen, zum Restaging und zum Follow-up benutzt. Methoden: Gruppe I: 17 Patienten mit primaerem kutanem Melanom erhielten LS, WB PET und eine operative SLN-Entfernung. Die WB PET-Ergebnisse wurden mit den SLN-Biopsien verglichen und zum Screening fuer Fernmetastasen benutzt. Gruppe

  9. Individual cerebral metabolic deficits in Alzheimer's disease and amnestic mild cognitive impairment: an FDG PET study

    International Nuclear Information System (INIS)

    Del Sole, Angelo; Lecchi, Michela; Lucignani, Giovanni; Clerici, Francesca; Mariani, Claudio; Maggiore, Laura; Chiti, Arturo; Mosconi, Lisa

    2008-01-01

    The purpose of the study was the identification of group and individual subject patterns of cerebral glucose metabolism (CMRGlu) in patients with Alzheimer's disease (AD) and with amnestic mild cognitive impairment (aMCI). [ 18 F]fluorodeoxyglucose positron emission tomography (PET) studies and neuropsychological tests were performed in 16 aMCI patients (ten women, age 75 ± 8 years) and in 14 AD patients (ten women, age 75 ± 9 years). Comparisons between patient subgroups and with a control population were performed using Statistical Parametric Mapping. Clusters of low CMRGlu were observed bilaterally in the posterior cingulate cortex (PCC), in the precuneus, in the inferior parietal lobule and middle temporal gyrus of AD patients. In aMCI patients, reduced CMRGlu was found only in PCC. Areas of low CMRGlu in PCC were wider in AD compared to aMCI and extended to the precuneus, while low CMRGlu was found in the lateral parietal cortex in AD but not in aMCI patients. Individual subject pattern analysis revealed that 86% of AD patients had low CMRGlu in the PCC (including the precuneus in 71%), 71% in the temporal cortex, 64% in the parietal cortex and 35% in the frontal cortex. Among the aMCI patients, 56% had low CMRGlu in the PCC, 44% in the temporal cortex, 18% in the frontal cortex and none in the parietal cortex. This study demonstrates that both AD and aMCI patients have highly heterogeneous metabolic impairment. This potential of individual metabolic PET imaging in patients with AD and aMCI may allow timely identification of brain damage on individual basis and possibly help planning tailored early interventions. (orig.)

  10. Complementary PET studies of striatal neuronal function in the differential diagnosis between multiple system atrophy and Parkinson's disease

    NARCIS (Netherlands)

    Antonini, A; Leenders, KL; Vontobel, P; Maguire, RP; Missimer, J; Psylla, M; Gunther, [No Value

    1997-01-01

    We used PET with the tracers [F-18]fluorodeoxyglucose (FDG), [F-18]fluorodopa (FDOPA) and [C-11]raclopride (RACLO) to study striatal glucose and dopa metabolism, and dopamine D-2 receptor binding, respectively, in nine patients with multiple system atrophy. Ten patients with classical Parkinson's

  11. Temporal dynamics of cortical and subcortical responses to apomorphine in Parkinson disease: an H2(15)O PET study

    NARCIS (Netherlands)

    Hosey, Lara A.; Thompson, Jennifer L. W.; Metman, Leonard Verhagen; van den Munckhof, Pepyn; Braun, Allen R.

    2005-01-01

    H2(15)O positron emission tomography (PET) was used to study the temporal course of central nervous system (CNS) responses to apomorphine in patients with idiopathic Parkinson disease (PD). Agonist-induced changes in regional cerebral blood flow (rCBF) were evaluated within

  12. MRI, PET/CT and ultrasound in the preoperative staging of endometrial cancer - A multicenter prospective comparative study

    DEFF Research Database (Denmark)

    Antonsen, Sofie Leisby; Jensen, Lisa Neerup; Loft, Annika

    2012-01-01

    OBJECTIVES: The aim of this prospective multicenter study was to evaluate and compare the diagnostic performance of PET/CT, MRI and transvaginal two-dimensional ultrasound (2DUS) in the preoperative assessment of endometrial cancer (EC). METHODS: 318 consecutive women with EC were included when...

  13. A Monte Carlo simulation study of the impact of novel scintillation crystals on performance characteristics of PET scanners

    DEFF Research Database (Denmark)

    Ghabrial, Amir; Franklin, Daniel; Zaidi, Habib

    2018-01-01

    Objective: The purpose of this study is to validate a Monte Carlo simulation model for the clinical Siemens Biograph mCT PET scanner using the GATE simulation toolkit, and to evaluate the performance of six different scintillation materials in this model using the National Electrical Manufactures...

  14. Labeling of BCNU with 11C and 13N and its in vivo pharmacokinetics study with PET

    International Nuclear Information System (INIS)

    Diksic, M.; Farrokhzad, S.; Yamamoto, L.; Feindel, W.

    1982-01-01

    1,3-bis(2-chloroethyl)-1-nitrosourea(BCNU) is an antitumor drug. 13 N and 11 C labeled BCNU were synthesized and made suitable for in vivo studies with positron emission tomography (PET). The optimization of the labeling procedures were discussed with an emphasis on the radiochemical yield and specific activity of the final product

  15. The predictive value of treatment response using FDG PET performed on day 21 of chemoradiotherapy in patients with oesophageal squamous cell carcinoma. A prospective, multicentre study (RTEP3)

    International Nuclear Information System (INIS)

    Palie, Odre; Vera, Pierre; Michel, Pierre; Di Fiore, Frederic; Menard, Jean-Francois; Rousseau, Caroline; Bridji, Boumediene; Rio, Emmanuel; Benyoucef, Ahmed; Meyer, Marc-Etienne; Jalali, Khadija; Bardet, Stephane; M'Vondo, Che Mabubu; Olivier, Pierre; Faure, Guillaume; Itti, Emmanuel; Diana, Christian; Houzard, Claire; Mornex, Francoise

    2013-01-01

    FDG PET has been suggested to have predictive value in the prognosis of oesophageal carcinoma. However, the retrospective studies reported in the literature have shown discordant results. Additionally, only four studies have evaluated FDG PET during chemoradiotherapy (CRT) in patients with different histological lesions. The purpose of this study was to investigate the predictive value of FDG PET performed early during CRT (on day 21) in a population of patients with oesophageal squamous cell carcinoma. Included in this prospective study were 57 patients with a histological diagnosis of squamous cell carcinoma of the oesophagus. Of these 57 patients, 48 (84 %) were evaluated (aged 63 ± 11 years; 44 men, 4 women). Each patient underwent FDG PET (4.5 MBq/kg) before CRT, according to the Herskovic protocol (t0; PET 1 ) and on day 21 ± 3 from the start of CRT (d21; PET 2 ). The response assessment included a clinical examination, CT scan or FDG PET and histological analysis 3 months and 1 year after PET 1 . The patients were classified as showing a complete response (CR) or a noncomplete response. A quantitative analysis was carried out for PET 1 and PET 2 using the following parameters: SUVmax, SUVmean (with SUVmean 40 as the 3-D volume at an SUVmax threshold of 40 % and SUVmean p as that defined by a physician), tumour volume (TV, with TV 40 defined as the TV at 40 % of SUVmax, and TV p as that defined by a physician); and the total lesion glycolysis (TLG, SUVmean x TV, with TLG 40 defined as the TLG at 40 % of SUVmax, and TLG p as that defined by a physician). The differences in responses at 3 months and 1 year between PET 1 (t0) and PET 2 (d21) were assessed in terms of variations in SUV, TV and TLG using a repeated measures of variance (ANOVA). SUVmax, SUVmean and TLG decreased significantly between PET 1 (t0) and PET 2 (d21; p p (p = 0.02); TV 40 did not decrease significantly. With respect to the predictive value of PET 1 , only TV 40 1 and TV p 1 values, and

  16. A prototype PET/SPECT/X-rays scanner dedicated for whole body small animal studies.

    Science.gov (United States)

    Rouchota, Maritina; Georgiou, Maria; Fysikopoulos, Eleftherios; Fragogeorgi, Eirini; Mikropoulos, Konstantinos; Papadimitroulas, Panagiotis; Kagadis, George; Loudos, George

    2017-01-01

    To present a prototype tri-modal imaging system, consisting of a single photon emission computed tomography (SPET), a positron emission tomography (PET), and a computed tomography (CT) subsystem, evaluated in planar mode. The subsystems are mounted on a rotating gantry, so as to be able to allow tomographic imaging in the future. The system, designed and constructed by our group, allows whole body mouse imaging of competent performance and is currently, to the best of our knowledge, unequaled in a national and regional level. The SPET camera is based on two Position Sensitive Photomultiplier Tubes (PSPMT), coupled to a pixilated Sodium Iodide activated with Thallium (NaI(Tl)) scintillator, having an active area of 5x10cm 2 . The dual head PET camera is also based on two pairs of PSPMT, coupled to pixelated berillium germanium oxide (BGO) scintillators, having an active area of 5x10cm 2 . The X-rays system consists of a micro focus X-rays tube and a complementary metal-oxide-semiconductor (CMOS) detector, having an active area of 12x12cm 2 . The scintigraphic mode has a spatial resolution of 1.88mm full width at half maximum (FWHM) and a sensitivity of 107.5cpm/0.037MBq at the collimator surface. The coincidence PET mode has an average spatial resolution of 3.5mm (FWHM) and a peak sensitivity of 29.9cpm/0.037MBq. The X-rays spatial resolution is 3.5lp/mm and the contrast discrimination function value is lower than 2%. A compact tri-modal system was successfully built and evaluated for planar mode operation. The system has an efficient performance, allowing accurate and informative anatomical and functional imaging, as well as semi-quantitative results. Compared to other available systems, it provides a moderate but comparable performance, at a fraction of the cost and complexity. It is fully open, scalable and its main purpose is to support groups on a national and regional level and provide an open technological platform to study different detector components and

  17. SU-E-J-263: Repeatability of SUV and Texture Parameters in Serial PET Studies

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, J; Humm, J; Nehmeh, S; Schoder, H [Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    2015-06-15

    Purpose: Standardized uptake values (SUV) are standard quantitative PET measures of FDG tumor uptake used,and are used as a tool to monitor response to therapy. Textural analysis is emerging as a new tool for assessing intratumoral heterogeneity which may allow better tissue characterization and improved prediction of response and survival rate.Understanding what variations may be expected in these parameters is key in order to make decisions based on how the change throughout the course of treatment. The aim of this study was to assess repeatability in SUV measures and texture parameters,and establish criteria that differentiate changes associated with treatment rather than statistical variability. Methods: Eighty patients,167 random lesions total,were scanned in a GE Discovery STE PET/CT Scanner. One field-of-view was chosen centered on the largest lesion observed in a clinical whole-body FDG PET.Immediately following,a gated 9 min scan was acquired in list mode,without changing the patient’s position between any scans. Data was replayed into 3 time bins,3 min each,in order to insure equivalent noise characteristics in each replicate.Data was reconstructed into 128×128×47 square matrices.One VOI was drawn over each lesion for each patient and used to segment all 3 replicates. The mean.max and peak SUV were calculated for each VOI and replicate. First-order textural features were also calculated (skewness and kurtosis). Repeatability was calculated as the average standard deviation over the mean for the 3 repeated measurements for each lesion. Results: The average percent error in the SUV max,peak and mean were 3.4%(0– 12.9%),1.9% (0–7.5%),2.8% (0–12.2%),respectively.For skewness and kurtosis they were 10.9% and 17.8%. Conclusion: We have shown that there is a large variation in %error in SUV measures across patients. SUVpeak is the least variable and kurtosis and skewness parameters are less reliable thatn SUVs.Higher order textures are be.

  18. SU-E-J-263: Repeatability of SUV and Texture Parameters in Serial PET Studies

    International Nuclear Information System (INIS)

    Schwartz, J; Humm, J; Nehmeh, S; Schoder, H

    2015-01-01

    Purpose: Standardized uptake values (SUV) are standard quantitative PET measures of FDG tumor uptake used,and are used as a tool to monitor response to therapy. Textural analysis is emerging as a new tool for assessing intratumoral heterogeneity which may allow better tissue characterization and improved prediction of response and survival rate.Understanding what variations may be expected in these parameters is key in order to make decisions based on how the change throughout the course of treatment. The aim of this study was to assess repeatability in SUV measures and texture parameters,and establish criteria that differentiate changes associated with treatment rather than statistical variability. Methods: Eighty patients,167 random lesions total,were scanned in a GE Discovery STE PET/CT Scanner. One field-of-view was chosen centered on the largest lesion observed in a clinical whole-body FDG PET.Immediately following,a gated 9 min scan was acquired in list mode,without changing the patient’s position between any scans. Data was replayed into 3 time bins,3 min each,in order to insure equivalent noise characteristics in each replicate.Data was reconstructed into 128×128×47 square matrices.One VOI was drawn over each lesion for each patient and used to segment all 3 replicates. The mean.max and peak SUV were calculated for each VOI and replicate. First-order textural features were also calculated (skewness and kurtosis). Repeatability was calculated as the average standard deviation over the mean for the 3 repeated measurements for each lesion. Results: The average percent error in the SUV max,peak and mean were 3.4%(0– 12.9%),1.9% (0–7.5%),2.8% (0–12.2%),respectively.For skewness and kurtosis they were 10.9% and 17.8%. Conclusion: We have shown that there is a large variation in %error in SUV measures across patients. SUVpeak is the least variable and kurtosis and skewness parameters are less reliable thatn SUVs.Higher order textures are be

  19. Canine study on myocardial ischemic memory with 18F-FDG PET/CT imaging

    International Nuclear Information System (INIS)

    Xie Boqia; Yang Minfu; Dou Kefei; Han Chunlei; Tian Yi; Zhang Ping; Yang Zihe; Yin Jiye; Wang Hao

    2012-01-01

    Objective: To explore whether the existence and duration of ischemia measured by dynamic 18 F-FDG PET/CT imaging correlated with the extent of myocardial ischemia in a canine model of myocardial ischemia-reperfusion. Methods: Canine coronary artery occlusion was carried out for 20 min (n=4) and for 40 min (n=4) followed by 24 h of open-artery reperfusion. All dogs underwent dynamic 18 F-FDG PET/CT and 99 Tc m -MIBI SPECT imaging at baseline and 1 h and 24 h after reperfusion.Quantitative analysis of myocardial 18 F-FDG uptake was performed using Carimas Core software,and the extraction ratio of 18 F-FDG (K) was calculated by the ratio of 18 F-FDG uptake rate in the ischemic area (k ischemia ) and normoperfused region (k normoperfused ). Echocardiographic data were also acquired between each PET/CT imaging study to detect the wall motion in the ischemic and normoperfused myocardium. Paired t test and non-parametric statistical tests, measured by SPSS 19.0, were used to analyze the data. Results: Coronary occlusion produced sustained, abnormal wall motion in the ischemic region for more than 1 h. Similar K values were demonstrated between the 20 min and 40 min groups at baseline (1.02 ±0.06 and 1.03 ±0.05, Z=-0.29, P>0.05). At 1 h after reperfusion, the reperfusion regions showed normal perfusion but with increased 18 F-FDG uptake, which was higher in the 40 min ischemic group than in the 20 min ischemic group (2.31 ±0.13 and 1.87 ±0.09, Z=-2.31, P<0.05). At 24 h after reperfusion, however, only the 40 min ischemic group showed slightly higher 18 F-FDG uptake than baseline (1.15 ± 0.02 and 1.03 ±0.05, t=4.32, P<0.05), whereas no significant difference was found in the 20 min ischemic group (1.05 ± 0.04 and 1.02 ± 0.06, t=0.87, P>0.05). Histological examination of the ischemic myocardium from both groups revealed neatly arranged cells without interstitial edema, hemorrhage nor inflammatory response. Conclusions: Myocardial 'ischemic memory' was

  20. Study of the radiosterilization dose effect on properties of poly(ethylene terephthalate) - PET recycled

    International Nuclear Information System (INIS)

    Isoldi, Ana Beatriz Godoy; Silva, Leonardo Gondim de Andrade e; Rosario, Salmo Cordeiro do

    2002-01-01

    The packing are in constant development, in function, especially, the process of globalization. The opening of the brazilian market after currency stabilization, caused technological innovations, change of habits and costumes of the population and environmental matters. Year after year, because of cost reductions, it became more extreme the hard study of the polymeric materials and their copolymers, their possible blends and their recycling, always seeking a better wrapping of the products, especially when it concerns to the food, increasing its shelf life. The process of sterilization of foods and modification of polymers through radiation are targets of growing interest by of the current industries linked to the nutrition and packing sectors. The objective of this paper is to discuss the application of the radiation (electron beam) in the sterilization of packings of recycled poly(ethylene terephthalate) PET, evaluating the possible effects on their properties. (author)

  1. Study of a Digital SiPM for TOF-PET

    CERN Document Server

    Heller, M

    2013-01-01

    The digital Silicon Photomultipliers (dSiPM) from Philips have been used in a study aiming at the proof of principle of an axial positron emission tomography detector with time of flight capabilities. These novel detectors provide various features not present in analog devices. The readout chain is programmable and offers various options affecting the functioning of the device. For each application a characterization and an optimization of the settings must be done in order to get the best out of the sensor. The axial geometry already developed for the AX-PET demonstrator implies the readout of LYSO crystals (used for energy measurement and transaxial coordinate) and of wavelength shifting (WLS) strips (axial coordinate). The readout of these two types of scintillators requires dedicated operation modes of the dSiPM. This technical note describes the characterization of the sensors with the goal of an optimized performance for LYSO crystals and WLS strips.

  2. Study of electrode pattern design for a CZT-based PET detector.

    Science.gov (United States)

    Gu, Y; Levin, C S

    2014-06-07

    We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3D positioning cadmium zinc telluride photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 to ~127.5 ns full width at half maximum (FWHM) for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips' weighting functions, which indicated a stronger 'small pixel' effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 to -80 V w.r.t. the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 versus 100 µm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns.

  3. Age-related changes in functional connectivity of cerebellar PlV: a FDG PET study

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sang Soo; Yoon, Eun Jin; Bang, Seong Ae; Park, Hyun Soo; Kim, Yu Kyeong; Kim, Sang Eun [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    2007-07-01

    The cerebellum is known to have strong connection with cerebral cortex, and it shows the greatest mean shrinkage with aging. Changes in functional connectivity between cerebellum and cortical and subcortical cerebral areas possibly occur in normal aging. In this study, we tested changes of interregional connection between cerebellar posterior inferior vermis (PIV) and cerebrum in healthy subjects divided in three classes of age group (young: 20-30, middle age: 40-50, elderly: over 60 years) using FDG PET. 211 healthy subjects (age, 20-82 y; 134 female) were studied with resting-state brain glucose utilization measured by FDG-PET, cerebellar PIV activity after count-normalization to the whole gray matter mean count was extracted. Using PIV count as a 'seed', the maps of cross-correlation coefficients were computed by measuring the correlation between 'seed' and all the other brain voxels (P < 0.001 uncorrected, k = 100). Across all age groups, positive correlations of metabolic activity in the cerebellar PIV showed in cerebellum itself and bilateral thalamus. An extended positive correlation in cuneus which is served for visual information processing was observed in middle aged and elderly group differently from the young group. Also, in elderly group, this correlation was observed in the frontal areas such as right orbital and precentral gyri. Negative correlation implicating mutual inhibition between the areas was also founded in prefrontal and cingulate cortices and temporoparietal association areas. Comparing with the young group, in theses areas, enlarged negative correlations was founded with aging. We identified age related changes in cerebrocerebellar communication loop which reflect changes in local neuroplasticity in the normal aging brain. Present result may have implication for understanding the functional decline of cerebellum related cognitive ability as well as the deficit of motor coordination in normal aging and its compensation

  4. Regression analysis utilizing subjective evaluation of emotional experience in PET studies on emotions.

    Science.gov (United States)

    Aalto, Sargo; Wallius, Esa; Näätänen, Petri; Hiltunen, Jaana; Metsähonkala, Liisa; Sipilä, Hannu; Karlsson, Hasse

    2005-09-01

    A methodological study on subject-specific regression analysis (SSRA) exploring the correlation between the neural response and the subjective evaluation of emotional experience in eleven healthy females is presented. The target emotions, i.e., amusement and sadness, were induced using validated film clips, regional cerebral blood flow (rCBF) was measured using positron emission tomography (PET), and the subjective intensity of the emotional experience during the PET scanning was measured using a category ratio (CR-10) scale. Reliability analysis of the rating data indicated that the subjects rated the intensity of their emotional experience fairly consistently on the CR-10 scale (Cronbach alphas 0.70-0.97). A two-phase random-effects analysis was performed to ensure the generalizability and inter-study comparability of the SSRA results. Random-effects SSRAs using Statistical non-Parametric Mapping 99 (SnPM99) showed that rCBF correlated with the self-rated intensity of the emotional experience mainly in the brain regions that were identified in the random-effects subtraction analyses using the same imaging data. Our results give preliminary evidence of a linear association between the neural responses related to amusement and sadness and the self-evaluated intensity of the emotional experience in several regions involved in the emotional response. SSRA utilizing subjective evaluation of emotional experience turned out a feasible and promising method of analysis. It allows versatile exploration of the neurobiology of emotions and the neural correlates of actual and individual emotional experience. Thus, SSRA might be able to catch the idiosyncratic aspects of the emotional response better than traditional subtraction analysis.

  5. The effects of thyroid hormones on brown adipose tissue in humans: a PET-CT study.

    Science.gov (United States)

    Zhang, Qiongyue; Miao, Qing; Ye, Hongying; Zhang, Zhaoyun; Zuo, Chuantao; Hua, Fengchun; Guan, Yihui; Li, Yiming

    2014-09-01

    Brown adipose tissue (BAT) is important for energy expenditure through thermogenesis, although its regulatory factors are not well known in humans. There is evidence suggesting that thyroid hormones affect BAT functions in some mammals, but the effects of thyroid hormones on BAT activity in humans are still unclear. The aim of this study was to investigate the effects of thyroid hormones on glucose metabolism of BAT and other organs in humans. Nine Graves' disease-caused hyperthyroid patients who were newly diagnosed and untreated were studied. Putative brown adipose tissue activity was determined by the integrated ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron-emission tomography and computed tomography (PET-CT). All hyperthyroid patients were treated with methimazole and had been monitored until their symptoms disappeared and thyroid hormone levels returned to normal. At the end, a second PET-CT scan was performed. The average follow-up period was 77 days. Meanwhile, compared with a group of seventy-five brown adipose tissue-negative controls, thyroid hormones of seventy-five BAT-positive healthy subjects were measured. Active brown adipose tissue was not present in any of the hyperthyroid patients. However, one patient with normalized thyroid function showed active BAT after therapy. The free T3 levels and free T4 levels were significantly lower in the 75 BAT-positive subjects than in the BAT-negative subjects. All hyperthyroid patients showed symmetrically increased uptake of fluorodeoxyglucose in skeletal muscles before treatment, whereas, the standardized uptake value was substantially decreased after treatment. Abnormally high circulating thyroid hormone levels may not increase brown adipose tissue activity, which may be limited by the increased obligatory thermogenesis of muscle in adult humans. Copyright © 2014 John Wiley & Sons, Ltd.

  6. Metabolic activity in the insular cortex and hypothalamus predicts hot flashes: an FDG-PET study.

    Science.gov (United States)

    Joffe, Hadine; Deckersbach, Thilo; Lin, Nancy U; Makris, Nikos; Skaar, Todd C; Rauch, Scott L; Dougherty, Darin D; Hall, Janet E

    2012-09-01

    Hot flashes are a common side effect of adjuvant endocrine therapies (AET; leuprolide, tamoxifen, aromatase inhibitors) that reduce quality of life and treatment adherence in breast cancer patients. Because hot flashes affect only some women, preexisting neurobiological traits might predispose to their development. Previous studies have implicated the insula during the perception of hot flashes and the hypothalamus in thermoregulatory dysfunction. The aim of the study was to understand whether neurobiological factors predict hot flashes. [18F]-Fluorodeoxyglucose (FDG) positron emission tomography (PET) brain scans coregistered with structural magnetic resonance imaging were used to determine whether metabolic activity in the insula and hypothalamic thermoregulatory and estrogen-feedback regions measured before and in response to AET predict hot flashes. Findings were correlated with CYP2D6 genotype because of CYP2D6 polymorphism associations with tamoxifen-induced hot flashes. We measured regional cerebral metabolic rate of glucose uptake (rCMRglu) in the insula and hypothalamus on FDG-PET. Of 18 women without hot flashes who began AET, new-onset hot flashes were reported by 10 (55.6%) and were detected objectively in nine (50%) participants. Prior to the use of all AET, rCMRglu in the insula (P ≤ 0.01) and hypothalamic thermoregulatory (P = 0.045) and estrogen-feedback (P = 0.007) regions was lower in women who reported developing hot flashes. In response to AET, rCMRglu was further reduced in the insula in women developing hot flashes (P ≤ 0.02). Insular and hypothalamic rCMRglu levels were lower in intermediate than extensive CYP2D6 metabolizers. Trait neurobiological characteristics predict hot flashes. Genetic variability in CYP2D6 may underlie the neurobiological predisposition to hot flashes induced by AET.

  7. Age-related changes in functional connectivity of cerebellar PlV: a FDG PET study

    International Nuclear Information System (INIS)

    Cho, Sang Soo; Yoon, Eun Jin; Bang, Seong Ae; Park, Hyun Soo; Kim, Yu Kyeong; Kim, Sang Eun

    2007-01-01

    The cerebellum is known to have strong connection with cerebral cortex, and it shows the greatest mean shrinkage with aging. Changes in functional connectivity between cerebellum and cortical and subcortical cerebral areas possibly occur in normal aging. In this study, we tested changes of interregional connection between cerebellar posterior inferior vermis (PIV) and cerebrum in healthy subjects divided in three classes of age group (young: 20-30, middle age: 40-50, elderly: over 60 years) using FDG PET. 211 healthy subjects (age, 20-82 y; 134 female) were studied with resting-state brain glucose utilization measured by FDG-PET, cerebellar PIV activity after count-normalization to the whole gray matter mean count was extracted. Using PIV count as a 'seed', the maps of cross-correlation coefficients were computed by measuring the correlation between 'seed' and all the other brain voxels (P < 0.001 uncorrected, k = 100). Across all age groups, positive correlations of metabolic activity in the cerebellar PIV showed in cerebellum itself and bilateral thalamus. An extended positive correlation in cuneus which is served for visual information processing was observed in middle aged and elderly group differently from the young group. Also, in elderly group, this correlation was observed in the frontal areas such as right orbital and precentral gyri. Negative correlation implicating mutual inhibition between the areas was also founded in prefrontal and cingulate cortices and temporoparietal association areas. Comparing with the young group, in theses areas, enlarged negative correlations was founded with aging. We identified age related changes in cerebrocerebellar communication loop which reflect changes in local neuroplasticity in the normal aging brain. Present result may have implication for understanding the functional decline of cerebellum related cognitive ability as well as the deficit of motor coordination in normal aging and its compensation mechanism of brain

  8. Guided transmission of highly charged ions through nanocapillaries in PET. Study of the energy dependencies

    International Nuclear Information System (INIS)

    Helhammer, R.; Pesic, Z.D.; Sobocinski, P.; Bundesmann, J.; Fink, D.; Stolterfoht, N.; Sulik, B.

    2004-01-01

    Full text: Recently we reported experiments in which slow highly charged ions are transmitted through nanocapillaries of 100nm diameter in an insulating PET foil of 10μm thickness [1]. The results of this work differ significantly from previous studies, which have been focused on capillaries in metals [2]. We measured the transmission of 3 keV Ne 7+ ions through the capillaries and focused the attention on ions whose charge has not changed during the passage through the capillary. The observation that the angular distribution for PET has a peak maximum whose position is equal to the tilt angle indicates a guiding of the Ne 7+ ion within the capillary. This guiding shows that the inner walls of the capillaries are charged up in a self-organizing process and collisions with the surface are finally prevented. We studied the time evolution of the capillary guiding as well as dependencies on the tilt angle [3]. Our most recent measurements were focussed on the investigation of the energy dependency for the guiding of Ne 7+ through capillaries. The measurements were done in an energy range from 2 keV up to 10 keV.We measured higher guiding efficiency for lower energies consistent with a previously developed model, which predicted an increase of the guiding efficiency with decreasing projectile energy [3]. In addition we found the effect of a narrower width of the angular distribution of transmitted ions. This effect is also well described by the model. However, further work is needed to explain the amount of charges to build up the deflection field at the end of the capillaries

  9. Challenges in the development of dopamine D2- and D3-selective radiotracers for PET imaging studies.

    Science.gov (United States)

    Mach, Robert H; Luedtke, Robert R

    2018-03-01

    The dopamine D2-like receptors (ie, D2/3 receptors) have been the most extensively studied CNS receptor with Positron Emission Tomography (PET). The 3 different radiotracers that have been used in these studies are [ 11 C]raclopride, [ 18 F]fallypride, and [ 11 C]PHNO. Because these radiotracers have a high affinity for both dopamine D2 and D3 receptors, the density of dopamine receptors in the CNS is reported as the D2/3 binding potential, which reflects a measure of the density of both receptor subtypes. Although the development of D2- and D3-selective PET radiotracers has been an active area of research for many years, this by and large presents an unmet need in the area of translational PET imaging studies. This article discusses some of the challenges that have inhibited progress in this area of research and the current status of the development of subtype selective radiotracers for imaging D3 and D2 dopamine receptors with PET. Copyright © 2017 John Wiley & Sons, Ltd.

  10. A new 18F-labelled derivative of the MMP inhibitor CGS 27023A for PET: Radiosynthesis and initial small-animal PET studies

    International Nuclear Information System (INIS)

    Wagner, Stefan; Breyholz, Hans-Joerg; Hoeltke, Carsten; Faust, Andreas; Schober, Otmar; Schaefers, Michael; Kopka, Klaus

    2009-01-01

    The CGS 27023A derivative (R)-2-(N-((6-fluoropyridin-3-yl) methyl)-4-methoxyphenyl-sulphonamido)-N-hydroxy-3-methylbutanamide 1a was identified as a very potent matrix metalloproteinase inhibitor. Here, we describe a one-step radiosynthesis of the target compound [ 18 F]1a. The syntheses of [ 18 F]1a resulted in a radiochemical yield of 12.1±5.9% (decay-corrected), a radiochemical purity of 98.8±0.6%, and a specific activity of 39±27 GBq/μmol at the end of synthesis within 160±18 min from the end of radionuclide production (n=5). Initial small-animal PET studies in wild-type mice (C57/BL6) showed no unfavourable tissue accumulation of [ 18 F]1a

  11. Automated High-Throughput Genotyping for Study of Global Epidemiology of Mycobacterium tuberculosis Based on Mycobacterial Interspersed Repetitive Units

    Science.gov (United States)

    Supply, Philip; Lesjean, Sarah; Savine, Evgueni; Kremer, Kristin; van Soolingen, Dick; Locht, Camille

    2001-01-01

    Large-scale genotyping of Mycobacterium tuberculosis is especially challenging, as the current typing methods are labor-intensive and the results are difficult to compare among laboratories. Here, automated typing based on variable-number tandem repeats (VNTRs) of genetic elements named mycobacterial interspersed repetitive units (MIRUs) in 12 mammalian minisatellite-like loci of M. tuberculosis is presented. This system combines analysis of multiplex PCRs on a fluorescence-based DNA analyzer with computerized automation of the genotyping. Analysis of a blinded reference set of 90 strains from 38 countries (K. Kremer et al., J. Clin. Microbiol. 37:2607–2618, 1999) demonstrated that it is 100% reproducible, sensitive, and specific for M. tuberculosis complex isolates, a performance that has not been achieved by any other typing method tested in the same conditions. MIRU-VNTRs can be used for analysis of the global genetic diversity of M. tuberculosis complex strains at different levels of evolutionary divergence. To fully exploit the portability of this typing system, a website was set up for the analysis of M. tuberculosis MIRU-VNTR genotypes via the Internet. This opens the way for global epidemiological surveillance of tuberculosis and should lead to novel insights into the evolutionary and population genetics of this major pathogen. PMID:11574573

  12. Impact of muscular uptake and statistical noise on tumor quantification based on simulated FDG-PET studies

    International Nuclear Information System (INIS)

    Silva-Rodríguez, Jesús; Domínguez-Prado, Inés; Pardo-Montero, Juan; Ruibal, Álvaro

    2017-01-01

    Purpose: The aim of this work is to study the effect of physiological muscular uptake variations and statistical noise on tumor quantification in FDG-PET studies. Methods: We designed a realistic framework based on simulated FDG-PET acquisitions from an anthropomorphic phantom that included different muscular uptake levels and three spherical lung lesions with diameters of 31, 21 and 9 mm. A distribution of muscular uptake levels was obtained from 136 patients remitted to our center for whole-body FDG-PET. Simulated FDG-PET acquisitions were obtained by using the Simulation System for Emission Tomography package (SimSET) Monte Carlo package. Simulated data was reconstructed by using an iterative Ordered Subset Expectation Maximization (OSEM) algorithm implemented in the Software for Tomographic Image Reconstruction (STIR) library. Tumor quantification was carried out by using estimations of SUV max , SUV 50 and SUV mean from different noise realizations, lung lesions and multiple muscular uptakes. Results: Our analysis provided quantification variability values of 17–22% (SUV max ), 11–19% (SUV 50 ) and 8–10% (SUV mean ) when muscular uptake variations and statistical noise were included. Meanwhile, quantification variability due only to statistical noise was 7–8% (SUV max ), 3–7% (SUV 50 ) and 1–2% (SUV mean ) for large tumors (>20 mm) and 13% (SUV max ), 16% (SUV 50 ) and 8% (SUV mean ) for small tumors (<10 mm), thus showing that the variability in tumor quantification is mainly affected by muscular uptake variations when large enough tumors are considered. In addition, our results showed that quantification variability is strongly dominated by statistical noise when the injected dose decreases below 222 MBq. Conclusions: Our study revealed that muscular uptake variations between patients who are totally relaxed should be considered as an uncertainty source of tumor quantification values. - Highlights: • Distribution of muscular uptake from 136 PET

  13. A prospective study to evaluate the impact of FDG-PET on CT-based radiotherapy treatment planning for oesophageal cancer

    International Nuclear Information System (INIS)

    Leong, Trevor; Everitt, Craig; Yuen, Kally; Condron, Sara; Hui, Andrew; Ngan, Samuel Y.K.; Pitman, Alexander; Lau, Eddie W.F.; MacManus, Michael; Binns, David; Ackerly, Trevor; Hicks, Rodney J.

    2006-01-01

    Background and purpose: This prospective study sought to determine how the use of combined PET/CT for radiotherapy treatment planning of oesophageal cancer would alter the delineation of tumour volumes compared to CT alone if PET/CT is assumed to more accurately represent true disease extent. Patients and methods: All patients underwent FDG-PET/CT scanning in the radiotherapy treatment position. For each patient, two separate gross tumour volumes (GTV) were defined, one based on CT images alone (GTV-CT) and another based on combined PET/CT data (GTV-PET). Corresponding planning target volumes (PTV) were generated, and separate treatment plans were then produced. For each patient, volumetric analysis of GTV-CT, PTV-CT and GTV-PET was performed to quantify the proportion of PET-avid disease that was not included in the GTV and PTV (geographic miss) if CT data alone were used for radiotherapy planning. Assessment of the cranial and caudal extent of the primary oesophageal tumour as defined by CT alone vs PET/CT was also compared. Results: The addition of PET information altered the clinical stage in 8 of 21 eligible patients enrolled on the study (38%); 4 patients had distant metastatic disease and 4 had unsuspected regional nodal disease. Sixteen patients proceeded to the radiotherapy planning phase of the study and received definitive chemoradiation planned with the PET/CT data set. The GTV based on CT information alone excluded PET-avid disease in 11 patients (69%), and in five patients (31%) this would have resulted in a geographic miss of gross tumour. The discordance between CT and PET/CT was due mainly to differences in defining the longitudinal extent of disease in the oesophagus. The cranial extent of the primary tumour as defined by CT vs PET/CT differed in 75% of cases, while the caudal extent differed in 81%. Conclusions: This study demonstrates that if combined PET/CT is used for radiotherapy treatment planning, there may be alterations to the delineation

  14. Pilot Study of 64CuCl2 for PET Imaging of Inflammation

    Directory of Open Access Journals (Sweden)

    Lei Jiang

    2018-02-01

    Full Text Available Copper(II ion (Cu2+ is the essential element for numerous pathophysiological processes in vivo. Copper transporter 1 (CTR1 is mainly responsible for maintaining Cu2+ accumulation in cells, which has been found to be over-expressed in inflammatory tissues. Therefore, we explored the potential application of 64CuCl2 for PET imaging of inflammation through targeting CTR1. The animal models of H2O2 induced muscle inflammation and lipopolysaccaharide induced lung inflammation were successfully established, then imaged by small animal PET (PET/CT post-injection of 64CuCl2, and PET images were quantitatively analyzed. H&E and immunohistochemical (IHC staining and western blot experiments were performed for evaluating CTR1 levels in the inflammatory and control tissues. Both inflammatory muscle and lungs can be clearly imaged by PET. PET image quantitative analysis revealed that the inflammatory muscle and lungs showed significantly higher 64Cu accumulation than the controls, respectively (p < 0.05. Furthermore, IHC staining and western blot analysis demonstrated that compared with the controls, CTR1 expression was increased in both the inflammatory muscle and lungs, which was consistent with the levels of 64Cu2+ accumulation in these tissues. 64CuCl2 can be used as a novel, simple, and highly promising PET tracer for CTR1 targeted imaging of inflammation.

  15. Spectral Analysis of Dynamic PET Studies: A Review of 20 Years of Method Developments and Applications.

    Science.gov (United States)

    Veronese, Mattia; Rizzo, Gaia; Bertoldo, Alessandra; Turkheimer, Federico E

    2016-01-01

    In Positron Emission Tomography (PET), spectral analysis (SA) allows the quantification of dynamic data by relating the radioactivity measured by the scanner in time to the underlying physiological processes of the system under investigation. Among the different approaches for the quantification of PET data, SA is based on the linear solution of the Laplace transform inversion whereas the measured arterial and tissue time-activity curves of a radiotracer are used to calculate the input response function of the tissue. In the recent years SA has been used with a large number of PET tracers in brain and nonbrain applications, demonstrating that it is a very flexible and robust method for PET data analysis. Differently from the most common PET quantification approaches that adopt standard nonlinear estimation of compartmental models or some linear simplifications, SA can be applied without defining any specific model configuration and has demonstrated very good sensitivity to the underlying kinetics. This characteristic makes it useful as an investigative tool especially for the analysis of novel PET tracers. The purpose of this work is to offer an overview of SA, to discuss advantages and limitations of the methodology, and to inform about its applications in the PET field.

  16. Effects of blood glucose level on FDG uptake by liver: a FDG-PET/CT study

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, Kazuo, E-mail: kkubota@cpost.plala.or.j [Division of Nuclear Medicine, Department of Radiology, National Center for Global Health and Medicine, Tokyo 162-8655 (Japan); Watanabe, Hiroshige; Murata, Yuji [Department of Radiology, Faculty of Medicine, Tokyo Medical and Dental University, Tokyo 113-8519 (Japan); Yukihiro, Masashi; Ito, Kimiteru; Morooka, Miyako; Minamimoto, Ryogo [Division of Nuclear Medicine, Department of Radiology, National Center for Global Health and Medicine, Tokyo 162-8655 (Japan); Hori, Ai [Department of Epidemiology and International Health, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655 (Japan); Shibuya, Hitoshi [Department of Radiology, Faculty of Medicine, Tokyo Medical and Dental University, Tokyo 113-8519 (Japan)

    2011-04-15

    In FDG-PET for abdominal malignancy, the liver may be assumed as an internal standard for grading abnormal FDG uptake both in early images and in delayed images. However, physiological variables of FDG uptake by the liver, especially the effects of blood glucose level, have not yet been elucidated. Methods: FDG-PET studies of 70 patients examined at 50 to 70 min after injection (60{+-}10 min: early images) and of 68 patients examined at 80 to 100 min after injection (90{+-}10 min: delayed images) were analyzed for liver FDG uptake. Patients having lesions in the liver, spleen and pancreas; patients having bulk tumor in other areas; and patients early after chemotherapy or radiotherapy were excluded; also, patients with blood glucose level over 125 mg/dl were excluded. Results: Mean standardized uptake value (SUV) of the liver, blood glucose level and sex showed no significant differences between early images and delayed images. However, liver SUV in the delayed image showed a larger variation than that in the early image and showed significant correlation to blood glucose level. The partial correlation coefficient between liver SUV and blood glucose level in the delayed image with adjustment for sex and age was 0.73 (P<.0001). Multivariate regression coefficient (95% confidence interval) of blood glucose was 0.017 (0.013-0.021). Conclusion: Blood glucose level is an important factor affecting the normal liver FDG uptake in nondiabetic patients. In the case of higher glucose level, liver FDG uptake is elevated especially in the delayed image. This may be due to the fact that the liver is the key organ responsible for glucose metabolism through gluconeogenesis and glycogen storage.

  17. Transcranial direct current stimulation to lessen neuropathic pain after spinal cord injury: a mechanistic PET study.

    Science.gov (United States)

    Yoon, Eun Jin; Kim, Yu Kyeong; Kim, Hye-Ri; Kim, Sang Eun; Lee, Youngjo; Shin, Hyung Ik

    2014-01-01

    It is suggested that transcranial direct current stimulation (tDCS) can produce lasting changes in corticospinal excitability and can potentially be used for the treatment of neuropathic pain. However, the detailed mechanisms underlying the effects of tDCS are unknown. We investigated the underlying neural mechanisms of tDCS for chronic pain relief using [(18)F]-fluorodeoxyglucose positron emission tomography ([(18)F]FDG-PET). Sixteen patients with neuropathic pain (mean age 44.1 ± 8.6 years, 4 females) due to traumatic spinal cord injury received sham or active anodal stimulation of the motor cortex using tDCS for 10 days (20 minutes, 2 mA, twice a day). The effect of tDCS on regional cerebral glucose metabolism was evaluated by [(18)F]FDG-PET before and after tDCS sessions. There was a significant decrease in the numeric rating scale scores for pain, from 7.6 ± 0.5 at baseline to 5.9 ± 1.8 after active tDCS (P = .016). We found increased metabolism in the medulla and decreased metabolism in the left dorsolateral prefrontal cortex after active tDCS treatment compared with the changes induced by sham tDCS. Additionally, an increase in metabolism after active tDCS was observed in the subgenual anterior cingulate cortex and insula. The results of this study suggest that anodal stimulation of the motor cortex using tDCS can modulate emotional and cognitive components of pain and normalize excessive attention to pain and pain-related information.

  18. Metabolically active tumour volume segmentation from dynamic [(18)F]FLT PET studies in non-small cell lung cancer.

    Science.gov (United States)

    Hoyng, Lieke L; Frings, Virginie; Hoekstra, Otto S; Kenny, Laura M; Aboagye, Eric O; Boellaard, Ronald

    2015-01-01

    Positron emission tomography (PET) with (18)F-3'-deoxy-3'-fluorothymidine ([(18)F]FLT) can be used to assess tumour proliferation. A kinetic-filtering (KF) classification algorithm has been suggested for segmentation of tumours in dynamic [(18)F]FLT PET data. The aim of the present study was to evaluate KF segmentation and its test-retest performance in [(18)F]FLT PET in non-small cell lung cancer (NSCLC) patients. Nine NSCLC patients underwent two 60-min dynamic [(18)F]FLT PET scans within 7 days prior to treatment. Dynamic scans were reconstructed with filtered back projection (FBP) as well as with ordered subsets expectation maximisation (OSEM). Twenty-eight lesions were identified by an experienced physician. Segmentation was performed using KF applied to the dynamic data set and a source-to-background corrected 50% threshold (A50%) was applied to the sum image of the last three frames (45- to 60-min p.i.). Furthermore, several adaptations of KF were tested. Both for KF and A50% test-retest (TRT) variability of metabolically active tumour volume and standard uptake value (SUV) were evaluated. KF performed better on OSEM- than on FBP-reconstructed PET images. The original KF implementation segmented 15 out of 28 lesions, whereas A50% segmented each lesion. Adapted KF versions, however, were able to segment 26 out of 28 lesions. In the best performing adapted versions, metabolically active tumour volume and SUV TRT variability was similar to those of A50%. KF misclassified certain tumour areas as vertebrae or liver tissue, which was shown to be related to heterogeneous [(18)F]FLT uptake areas within the tumour. For [(18)F]FLT PET studies in NSCLC patients, KF and A50% show comparable tumour volume segmentation performance. The KF method needs, however, a site-specific optimisation. The A50% is therefore a good alternative for tumour segmentation in NSCLC [(18)F]FLT PET studies in multicentre studies. Yet, it was observed that KF has the potential to subsegment

  19. Imbalance between abstract and concrete repetitive thinking modes in schizophrenia.

    Science.gov (United States)

    Maurage, Pierre; Philippot, Pierre; Grynberg, Delphine; Leleux, Dominique; Delatte, Benoît; Mangelinckx, Camille; Belge, Jan-Baptist; Constant, Eric

    2017-10-01

    Repetitive thoughts can be divided in two modes: abstract/analytic (decontextualized and dysfunctional) and concrete/experiential (problem-focused and adaptive). They constitute a transdiagnostic process involved in many psychopathological states but have received little attention in schizophrenia, as earlier studies only indexed increased ruminations (related to dysfunctional repetitive thoughts) without jointly exploring both modes. This study explored the two repetitive thinking modes, beyond ruminations, to determine their imbalance in schizophrenia. Thirty stabilized patients with schizophrenia and 30 matched controls completed the Repetitive Response Scale and the Mini Cambridge-Exeter Repetitive Thought Scale, both measuring repetitive thinking modes. Complementary measures related to schizophrenic symptomatology, depression and anxiety were also conducted. Compared to controls, patients with schizophrenia presented an imbalance between repetitive thinking modes, with increased abstract/analytic and reduced concrete/experiential thoughts, even after controlling for comorbidities. Schizophrenia is associated with stronger dysfunctional repetitive thoughts (i.e. abstract thinking) and impaired ability to efficiently use repetitive thinking for current problem-solving (i.e. concrete thinking). This imbalance confirms the double-faced nature of repetitive thinking modes, whose influence on schizophrenia's symptomatology should be further investigated. The present results also claim for evaluating these processes in clinical settings and for rehabilitating the balance between opposite repetitive thinking modes. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. A Prospective Study Comparing 99mTc-Hydroxyethylene-Diphosphonate Planar Bone Scintigraphy and Whole-Body SPECT/CT with 18F-Fluoride PET/CT and 18F-Fluoride PET/MRI for Diagnosing Bone Metastases.

    Science.gov (United States)

    Löfgren, Johan; Mortensen, Jann; Rasmussen, Sine H; Madsen, Claus; Loft, Annika; Hansen, Adam E; Oturai, Peter; Jensen, Karl Erik; Mørk, Mette Louise; Reichkendler, Michala; Højgaard, Liselotte; Fischer, Barbara M

    2017-11-01

    metastases (14%) is likely limited. This conclusion is influenced by the low prevalence of patients with osseous metastases. There may well be significant differences in the sensitivity of SPECT/CT, PET/CT, and PET/MRI compared with pBS, but a larger patient population or a patient population with a higher prevalence of bone metastases would have to be studied to demonstrate this. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

  1. Acute S-ketamine application does not alter cerebral [18F]altanserin binding: a pilot PET study in humans

    International Nuclear Information System (INIS)

    Matusch, A.; Rota Kops, E.; Winz, O.H.; Elmenhorst, D.; Herzog, H.; Hurlemann, R.; Zilles, K.; Bauer, A.

    2007-01-01

    Modeling short-term psychotic states with subanaesthetic doses of ketamine provides substantial experimental evidence in support of the glutamate hypothesis of schizophrenia. Ketamine exerts its pharmacological effects both directly via interactions with glutamate receptors and indir