WorldWideScience

Sample records for based positron emission

  1. Positron emission tomography.

    Science.gov (United States)

    Hoffman, E J; Phelps, M E

    1979-01-01

    Conventional nuclear imaging techniques utilizing lead collimation rely on radioactive tracers with little role in human physiology. The principles of imaging based on coincidence detection of the annihilation radiation produced in positron decay indicate that this mode of detection is uniquely suited for use in emission computed tomography. The only gamma-ray-emitting isotopes of carbon, nitrogen, and oxygen are positron emitters, which yield energies too high for conventional imaging techniques. Thus development of positron emitters in nuclear medicine imaging would make possible the use of a new class of physiologically active, positron-emitting radiopharmaceuticals. The application of these principles is described in the use of a physiologically active compound labeled with a positron emitter and positron-emission computed tomography to measure the local cerebral metabolic rate in humans. PMID:440173

  2. Knowledge-based automated radiopharmaceutical manufacturing for Positron Emission Tomography

    International Nuclear Information System (INIS)

    This article describes the application of basic knowledge engineering principles to the design of automated synthesis equipment for radiopharmaceuticals used in Positron Emission Tomography (PET). Before discussing knowledge programming, an overview of the development of automated radiopharmaceutical synthesis systems for PET will be presented. Since knowledge systems will rely on information obtained from machine transducers, a discussion of the uses of sensory feedback in today's automated systems follows. Next, the operation of these automated systems is contrasted to radiotracer production carried out by chemists, and the rationale for and basic concepts of knowledge-based programming are explained. Finally, a prototype knowledge-based system supporting automated radiopharmaceutical manufacturing of 18FDG at Brookhaven National Laboratory (BNL) is described using 1stClass, a commercially available PC-based expert system shell

  3. Tomography by positrons emission

    International Nuclear Information System (INIS)

    The tomography by positrons emission is a technology that allows to measure the concentration of positrons emission in a tri dimensional body through external measurements. Among the isotope emissions have carbon isotopes are (11C), of the oxygen (15O), of the nitrogen (13N) that are three the element that constitute the base of the organic chemistry. Theses have on of the PET's most important advantages, since many biological interesting organic molecules can be tracer with these isotopes for the metabolism studies 'in vivo' through PET, without using organic tracers that modify the metabolism. The mentioned isotopes, also possess the characteristic of having short lifetime, that constitute on of PET's advantages from the dosimetric point of view. Among 11C, 15O, and 13N, other isotopes that can be obtained of a generator as the 68Ga and 82Rb

  4. Positron emission tomography, physical bases and comparaison with other techniques

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a medical imaging technique that measures the three-dimensional distribution of molecules marked by a positron-emitting particle. PET has grown significantly in clinical fields, particularly in oncology for diagnosis and therapeutic follow purposes. The technical evolutions of this technique are fast. Among the technical improvements, is the coupling of the PET scan with computed tomography (CT). PET is obtained by intravenous injection of a radioactive tracer. The marker is usually fluorine (18F) embedded in a glucose molecule forming the 18-fluorodeoxyglucose (FDG-18). This tracer, similar to glucose, binds to tissues that consume large quantities of the sugar such cancerous tissue, cardiac muscle or brain. Detection using scintillation crystals (BGO, LSO, LYSO) suitable for high energy (511keV) recognizes the lines of the gamma photons originating from the annihilation of a positron with an electron. The electronics of detection or coincidence circuit is based on two criteria: a time window, of about 6 to 15 ns, and an energy window. This system measures the true coincidences that correspond to the detection of two photons of 511 kV from the same annihilation. Most PET devices are constituted by a series of elementary detectors distributed annularly around the patient. Each detector comprises a scintillation crystal matrix coupled to a finite number (4 or 6) of photomultipliers. The electronic circuit, or the coincidence circuit, determines the projection point of annihilation by means of two elementary detectors. The processing of such information must be extremely fast, considering the count rates encountered in practice. The information measured by the coincidence circuit is then positioned in a matrix or sinogram, which contains a set of elements of a projection section of the object. Images are obtained by tomographic reconstruction by powerful computer stations equipped with a software tools allowing the analysis and

  5. Positron-emission tomography

    International Nuclear Information System (INIS)

    Positron-emission tomography (PET) combines early biochemical assessment of pathology achieved by nuclear medicine with the precise localization achieved by computerized image reconstruction. In this technique a chemical compound with the desired biological activity is labeled with a radioactive isotope that decays by emitting a positron, or positive electron. With suitable interpretation PET images can provide a noninvasive, regional assessment of many biochemical processes that are essential to the functioning of the organ that is being visualized

  6. Fundamentals of positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography is a modern radionuclide method of measuring physiological quantities or metabolic parameters in vivo. The methods is based on: (1) Radioactive labelling with positron emitters; (2) the coincidence technique for the measurement of the annihilation radiation following positron decay; (3) analysis of the data measured using biological models. The basic aspects and problems of the method are discussed. The main fields of future research are the synthesis of new labelled compounds and the development of mathematical models of the biological processes to be investigated. (orig.)

  7. [Fundamentals of positron emission tomography].

    Science.gov (United States)

    Ostertag, H

    1989-07-01

    Positron emission tomography is a modern radionuclide method of measuring physiological quantities or metabolic parameters in vivo. The method is based on: (1) radioactive labelling with positron emitters; (2) the coincidence technique for the measurement of the annihilation radiation following positron decay; (3) analysis of the data measured using biological models. The basic aspects and problems of the method are discussed. The main fields of future research are the synthesis of new labelled compounds and the development of mathematical models of the biological processes to be investigated. PMID:2667029

  8. Positron emission tomography displacement sensitivity: predicting binding potential change for positron emission tomography tracers based on their kinetic characteristics.

    Science.gov (United States)

    Morris, Evan D; Yoder, Karmen K

    2007-03-01

    There is great interest in positron emission tomography (PET) as a noninvasive assay of fluctuations in synaptic neurotransmitter levels, but questions remain regarding the optimal choice of tracer for such a task. A mathematical method is proposed for predicting the utility of any PET tracer as a detector of changes in the concentration of an endogenous competitor via displacement of the tracer (a.k.a., its 'vulnerability' to competition). The method is based on earlier theoretical work by Endres and Carson and by the authors. A tracer-specific predictor, the PET Displacement Sensitivity (PDS), is calculated from compartmental model simulations of the uptake and retention of dopaminergic radiotracers in the presence of transient elevations of dopamine (DA). The PDS predicts the change in binding potential (DeltaBP) for a given change in receptor occupancy because of binding by the endogenous competitor. Simulations were performed using estimates of tracer kinetic parameters derived from the literature. For D(2)/D(3) tracers, the calculated PDS indices suggest a rank order for sensitivity to displacement by DA as follows: raclopride (highest sensitivity), followed by fallypride, FESP, FLB, NMSP, and epidepride (lowest). Although the PDS takes into account the affinity constant for the tracer at the binding site, its predictive value cannot be matched by either a single equilibrium constant, or by any one rate constant of the model. Values for DeltaBP have been derived from published studies that employed comparable displacement paradigms with amphetamine and a D(2)/D(3) tracer. The values are in good agreement with the PDS-predicted rank order of sensitivity to displacement. PMID:16788713

  9. Positron emission tomography

    International Nuclear Information System (INIS)

    The aim of this project is to provide a simple summary of new trends in positron emission tomography and its basic physical principles. It provides thereby compendious introduction of the trends of the present development in diagnostics using PET systems. A review of available literature was performed. (author)

  10. Positron emission tomography

    CERN Document Server

    Paans, A M J

    2006-01-01

    Positron Emission Tomography (PET) is a method for measuring biochemical and physiological processes in vivo in a quantitative way by using radiopharmaceuticals labelled with positron emitting radionuclides such as 11C, 13N, 15O and 18F and by measuring the annihilation radiation using a coincidence technique. This includes also the measurement of the pharmacokinetics of labelled drugs and the measurement of the effects of drugs on metabolism. Also deviations of normal metabolism can be measured and insight into biological processes responsible for diseases can be obtained. At present the combined PET/CT scanner is the most frequently used scanner for whole-body scanning in the field of oncology.

  11. Positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a method for quantitative imaging of regional physiological and biochemical parameters. Positron emitting radioactive isotopes can be produced by a cyclotron, eg. the biologically important carbon (11C), oxygen (15O), and nitrogen (13N) elements. With the tomographic principles of the PET scanner the quantitative distribution of the administered isotopes can be determined and images can be provided as well as dynamic information on blood flow, metabolism and receptor function. In neurology PET has been used for investigations on numerous physiological processes in the brain: circulation, metabolism and receptor studies. In Parkinson's disease PET studies have been able to localize the pathology specifically, and in early stroke PET technique can outline focal areas with living but non-functioning cells, and this could make it possible to intervene in this early state. With positron emission tomography a quantitative evaluation of myocardial blood flow, glucose and fatty acid metabolism can be made as well as combined assessments of blood flow and metabolism. Combined studies of blood flow and metabolism can determine whether myocardial segments with abnormal motility consist of necrotic or viable tissue, thereby delineating effects of revascularisation. In the future it will probably be possible to characterize the myocardial receptor status in different cardiac diseases. The PET technique is used in oncology for clinical as well as more basic research on tumor perfusion and metabolism. Further, tumor uptake of positron labelled cytotoxic drugs might predict the clinical benefit of treatment. (au) (19 refs.)

  12. Time resolution in scintillator based detectors for positron emission tomography

    International Nuclear Information System (INIS)

    In the domain of medical photon detectors L(Y)SO scintillators are used for positron emission tomography (PET). The interest for time of flight (TOF) in PET is increasing since measurements have shown that new crystals like L(Y)SO coupled to state of the art photodetectors, e.g. silicon photomultipliers (SiPM), can reach coincidence time resolutions (CTRs) of far below 500ps FWHM. To achieve these goals it is important to study the processe in the whole detection chain, i.e. the high energy particle or gamma interaction in the crystal, the scintillation process itself, the light propagation in the crystal with the light transfer to the photodetector, and the electronic readout. In this thesis time resolution measurements for a PET like system are performed in a coincidence setup utilizing the ultra fast amplifier discriminator NINO. We found that the time-over-threshold energy information provided by NINO shows a degradation in energy resolution for higher SiPM bias voltages. This is a consequence of the increasing dark count rate (DCR) of the SiPM with higher bias voltages together with the exponential decay of the signal. To overcome this problem and to operate the SiPM at its optimum voltage in terms of timing we developed a new electronic board that employs NINO only as a low noise leading edge discriminator together with an analog amplifier which delivers the energy information. With this new electronic board we indeed improved the measured CTR by about 15%. To study the limits of time resolution in more depth we measured the CTR with 2x2x3mm3 LSO:Ce codoped 0.4%Ca crystals coupled to commercially available SiPMs (Hamamatsu S10931-50P MPPC) and achieved a CTR of 108±5ps FWHM at an energy of 511keV. We determined the influence of the data acquisition system and the electronics on the CTR to be 27±2ps FWHM and thus negligible. To quantitatively understand the measured values, we developed a Monte Carlo simulation tool in MATLAB that incorporates the timing

  13. Instrumentation in positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a three-dimensional medical imaging technique that noninvasively measures the concentration of radiopharmaceuticals in the body that are labeled with positron emitters. With the proper compounds, PET can be used to measure metabolism, blood flow, or other physiological values in vivo. The technique is based on the physics of positron annihilation and detection and the mathematical formulations developed for x-ray computed tomography. Modern PET systems can provide three-dimensional images of the brain, the heart, and other internal organs with resolutions on the order of 4 to 6 mm. With the selectivity provided by a choice of injected compounds, PET has the power to provide unique diagnostic information that is not available with any other imaging modality. This is the first five reports on the nature and uses of PET that have been prepared for the American Medical Association's Council on Scientific Affairs by an authoritative panel

  14. Positron Emission Tomography (PET)

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs

  15. Positron emission mammography imaging

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W.

    2003-10-02

    This paper examines current trends in Positron Emission Mammography (PEM) instrumentation and the performance tradeoffs inherent in them. The most common geometry is a pair of parallel planes of detector modules. They subtend a larger solid angle around the breast than conventional PET cameras, and so have both higher efficiency and lower cost. Extensions to this geometry include encircling the breast, measuring the depth of interaction (DOI), and dual-modality imaging (PEM and x-ray mammography, as well as PEM and x-ray guided biopsy). The ultimate utility of PEM may not be decided by instrument performance, but by biological and medical factors, such as the patient to patient variation in radiotracer uptake or the as yet undetermined role of PEM in breast cancer diagnosis and treatment.

  16. Positron emission tomography. Basic principles

    International Nuclear Information System (INIS)

    The basic principles of positron emission tomography (PET) technique are reviewed. lt allows to obtain functional images from gamma rays produced by annihilation of a positron, a positive beta particle. This paper analyzes positron emitters production in a cyclotron, its general mechanisms, and the various detection systems. The most important clinical applications are also mentioned, related to oncological uses of fluor-l8-deoxyglucose

  17. Gamma camera based Positron Emission Tomography: a study of the viability on quantification

    International Nuclear Information System (INIS)

    Positron Emission Tomography (PET) is a Nuclear Medicine imaging modality for diagnostic purposes. Pharmaceuticals labeled with positron emitters are used and images which represent the in vivo biochemical process within tissues can be obtained. The positron/electron annihilation photons are detected in coincidence and this information is used for object reconstruction. Presently, there are two types of systems available for this imaging modality: the dedicated systems and those based on gamma camera technology. In this work, we utilized PET/SPECT systems, which also allows for the traditional Nuclear Medicine studies based on single photon emitters. There are inherent difficulties which affect quantification of activity and other indices. They are related to the Poisson nature of radioactivity, to radiation interactions with patient body and detector, noise due to statistical nature of these interactions and to all the detection processes, as well as the patient acquisition protocols. Corrections are described in the literature and not all of them are implemented by the manufacturers: scatter, attenuation, random, decay, dead time, spatial resolution, and others related to the properties of each equipment. The goal of this work was to assess these methods adopted by two manufacturers, as well as the influence of some technical characteristics of PET/SPECT systems on the estimation of SUV. Data from a set of phantoms were collected in 3D mode by one camera and 2D, by the other. We concluded that quantification is viable in PET/SPECT systems, including the estimation of SUVs. This is only possible if, apart from the above mentioned corrections, the camera is well tuned and coefficients for sensitivity normalization and partial volume corrections are applied. We also verified that the shapes of the sources used for obtaining these factors play a role on the final results and should be delt with carefully in clinical quantification. Finally, the choice of the region

  18. A Haar-wavelet-based Lucy-Richardson algorithm for positron emission tomography image restoration

    International Nuclear Information System (INIS)

    Deconvolution is an ill-posed problem that requires regularization. Noise would inevitably be enhanced during the iterative deconvolution process. The enhanced noise degrades the image quality, causing mistakes in clinical interpretations. This paper introduced a Haar-wavelet-based Lucy-Richardson algorithm (HALU) for positron emission tomography (PET) image restoration based on a spatially variant point spread function. After wavelet decomposition, Lucy-Richardson algorithm was applied to each approximation matrix with different iteration numbers. Thus, this enhanced the contrasts of our images without amplifying much of the noise level. The results showed that HALU can be able to recover the resolution and yield better contrast and lower noise level than the Lucy-Richardson algorithm.

  19. Decision logic for retreatment of asymptomatic lung cancer recurrence based on positron emission tomography findings

    International Nuclear Information System (INIS)

    Purpose: The purpose of the study was to determine if Positron emission tomography (PET) 2-[F-18] fluoro-2-deoxy-D-glucose (FDG) imaging could detect subclinical local lung cancer recurrence and whether retreatment of such recurrence was feasible and beneficial. Methods and Materials: Twenty patients with biopsy proven lung cancer were studied with Positron emission tomography for the purpose of detecting subclinical lung cancer recurrence over a period of 4.25 years. All patients were treated with external radiation as part or all of their therapy. Twenty patients had baseline PET and computed tomography (CT) studies for comparison with later studies. Surviving patients had a total of 40 sequential PET scans and 35 CT scans. The follow-up interval ranged from 5 to 40 months posttreatment. The differential uptake ratio (DUR) was determined for regions of interest of increased FDG uptake. Results: The median DUR value of the 20 baseline PET studies was 5.59. The DUR value of greater than 3 was empirically selected as being positive for tumor detection. On baseline studies, PET had a 100% correlation with the CT findings in regard to detection of the site of primary tumor involvement. Four of 20 patients showed areas of discordance in the mediastinal and hilar areas on initial PET and CT studies. Seven of 17 patients showed discordant posttreatment PET-CT findings. Two false positive PET studies were due to radiation pneumonitis and one to macrophage glycolysis in tumor necrosis. For detection of asymptomatic tumor recurrence, analysis of sequential PET and CT studies, biopsy results, and the patient's clinical course suggested that PET had a sensitivity of 100%, specificity of 89.3%, and accuracy of 92.5%. Computerized Tomography was found to have a sensitivity of 67%, specificity of 85%, and accuracy of 82% for detection of such early-stage recurrence. Five patients went on to have retreatment with external irradiation based upon the PET evidence. Four retreated

  20. NMF on positron emission tomography

    DEFF Research Database (Denmark)

    Bödvarsson, Bjarni; Hansen, Lars Kai; Svarer, Claus;

    2007-01-01

    In positron emission tomography, kinetic modelling of brain tracer uptake, metabolism or binding requires knowledge of the cerebral input function. Traditionally, this is achieved with arterial blood sampling in the arm or as shown in (Liptrot, M, et al., 2004) by non-invasive K-means clustering....... We propose another method to estimate time-activity curves (TAC) extracted directly from dynamic positron emission tomography (PET) scans by non-negative matrix factorization (NMF). Since the scaling of the basis curves is lost in the NMF the estimated TAC is scaled by a vector alpha which is...

  1. PETALO, a new concept for a Positron Emission TOF Apparatus based on Liquid xenOn

    CERN Document Server

    Benlloch-Rodriguez, J M

    2016-01-01

    This master thesis presents a new type of Positron Emission TOF Apparatus using Liquid xenOn (PETALO). The detector is based in the Liquid Xenon Scintillating Cell (LXSC). The cell is a box filled with liquid xenon (LXe) whose transverse dimensions are chosen to optimize packing and with a thickness optimized to contain a large fraction of the incoming photons. The entry and exit faces of the box (relative to the incoming gammas direction) are instrumented with large silicon photomultipliers (SiPMs), coated with a wavelength shifter, tetraphenyl butadiene (TPB). The non-instrumented faces are covered by reflecting Teflon coated with TPB. In this thesis we show that the LXSC can display an energy resolution of 5% FWHM, much better than that of conventional solid scintillators such as LSO/LYSO. The LXSC can measure the interaction point of the incoming photon with a resolution in the three coordinates of 1 mm. The very fast scintillation time of LXe (2 ns) and the availability of suitable sensors and electronic...

  2. Time based readout of a silicon photomultiplier (SiPM) for Time Of Flight Positron Emission Tomography (TOF-PET)

    OpenAIRE

    Jarron, P.; Despeisse, M.; Auffray, E; Brunner, S-E; Garutti, E.; Goettlich, M.; Hillemanns, H.; Lecoq, P.; Meyer, T.; Powolny, F.; W. Shen; Schultz-Coulon, H-C; Williams, C

    2009-01-01

    Time of flight (TOF) measurements in positron emission tomography (PET) are very challenging in terms of timing performance, and should achieve ideally less than 100ps FWHM precision. We present a time-based differential technique to read out SiPMs that has less than 25ps rms electronic jitter. The novel readout is a fast front end circuit (NINO) based on a first stage differential current mode amplifier with 20input resistance. Therefore the amplifier inputs are connected differentially to...

  3. Positron emission tomography and migraine

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a brain imaging technique that allows in vivo studies of numerous physiological parameters. There have been few PET studies in migraine patients. Cerebral blood flow changes with no variations in brain oxygen consumption have been reported in patients with prolonged neurologic manifestations during migraine attacks. Parenteral administration of reserpine during migraine headache has been followed by a fall in the overall cerebral uptake of glucose. The small sample sizes and a number of methodologic problems complicate the interpretation of these results. Recent technical advances and the development of new PET tracers can be expected to provide further insight into the pathophysiology of migraine. Today cerebral cortex 5 HT2 serotonin receptors can be studied in migraine patients with PET

  4. Positron emission tomography wrist detector

    Science.gov (United States)

    Schlyer, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois

    2006-08-15

    A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal representing a time-of-occurrence of an annihilation event, generating an address signal representing a channel detecting the annihilation event, and generating a channel signal including the time and address signals. The method also includes generating a composite signal including the channel signal and another similarly generated channel signal concerning another annihilation event. An apparatus that serially transfers annihilation information includes a time signal generator, address signal generator, channel signal generator, and composite signal generator. The time signal is asynchronous and the address signal is synchronous to a clock signal. A PET scanner includes a scintillation array, detection array, front-end array, and a serial encoder. The serial encoders include the time signal generator, address signal generator, channel signal generator, and composite signal generator.

  5. Positron emission tomography basic sciences

    CERN Document Server

    Townsend, D W; Valk, P E; Maisey, M N

    2003-01-01

    Essential for students, science and medical graduates who want to understand the basic science of Positron Emission Tomography (PET), this book describes the physics, chemistry, technology and overview of the clinical uses behind the science of PET and the imaging techniques it uses. In recent years, PET has moved from high-end research imaging tool used by the highly specialized to an essential component of clinical evaluation in the clinic, especially in cancer management. Previously being the realm of scientists, this book explains PET instrumentation, radiochemistry, PET data acquisition and image formation, integration of structural and functional images, radiation dosimetry and protection, and applications in dedicated areas such as drug development, oncology, and gene expression imaging. The technologist, the science, engineering or chemistry graduate seeking further detailed information about PET, or the medical advanced trainee wishing to gain insight into the basic science of PET will find this book...

  6. Scintillators for positron emission tomography

    International Nuclear Information System (INIS)

    Like most applications that utilize scintillators for gamma detection, Positron Emission Tomography (PET) desires materials with high light output, short decay time, and excellent stopping power that are also inexpensive, mechanically rugged, and chemically inert. Realizing that this ''ultimate'' scintillator may not exist, this paper evaluates the relative importance of these qualities and describes their impact on the imaging performance of PET. The most important PET scintillator quality is the ability to absorb 511 keV photons in a small volume, which affects the spatial resolution of the camera. The dominant factor is a short attenuation length (≤ 1.5 cm is required), although a high photoelectric fraction is also important (> 30% is desired). The next most important quality is a short decay time, which affects both the dead time and the coincidence timing resolution. Detection rates for single 511 keV photons can be extremely high, so decay times ≤ 500 ns are essential to avoid dead time losses. In addition, positron annihilations are identified by time coincidence so ≤5 ns fwhm coincidence pair timing resolution is required to identify events with narrow coincidence windows, reducing contamination due to accidental coincidences. Current trends in PET cameras are toward septaless, ''fully-3D'' cameras, which have significantly higher count rates than conventional 2-D cameras and so place higher demands on scintillator decay time. Light output affects energy resolution, and thus the ability of the camera to identify and reject events where the initial 511 keV photon has undergone Compton scatter in the patient. The scatter to true event fraction is much higher in fully-3D cameras than in 2-D cameras, so future PET cameras would benefit from scintillators with a 511 keV energy resolution < 10--12% fwhm

  7. Fluorodeoxyglucose-positron emission tomography in carcinoma nasopharynx: Can we predict outcomes and tailor therapy based on postradiotherapy fluorodeoxyglucose-positron emission tomography?

    Directory of Open Access Journals (Sweden)

    Sarbani Ghosh Laskar

    2016-01-01

    Full Text Available Background: Positron emission tomography-computed tomography (PET-CT is an emerging modality for staging and response evaluation in carcinoma nasopharynx. This study was conducted to evaluate the impact of PET-CT in assessing response and outcomes in carcinoma nasopharynx. Materials and Methods: Forty-five patients of nonmetastatic carcinoma nasopharynx who underwent PET-CT for response evaluation at 10-12 weeks posttherapy between 2004 and 2009 were evaluated. Patients were classified as responders (Group A if there was a complete response on PET-CT or as nonresponders (Group B if there was any uptake above the background activity. Data regarding demographics, treatment, and outcomes were collected from their records and compared across the Groups A and B. Results: The median age was 41 years. 42 out of 45 (93.3% patients had WHO Grade 2B disease (undifferentiated squamous carcinoma. 24.4%, 31.1%, 15.6, and 28.8% patients were in American Joint Committee on Cancer Stage IIb, III, Iva, and IVb. All patients were treated with neoadjuvant chemotherapy followed by concomitant chemoradiotherapy. Forty-five patients, 28 (62.2% were classified as responders, whereas 17 (37.8% were classified as nonresponders. There was no significant difference in the age, sex, WHO grade, and stage distribution between the groups. Compliance to treatment was comparable across both groups. The median follow-up was 25.3 months (759 days. The disease-free survival (DFS of the group was 57.3% at 3 years. The DFS at 3 years was 87.3% and 19.7% for Group A and B, respectively (log-rank test, P < 0.001. Univariate and multivariate analysis revealed Groups to be the only significant factor predicting DFS (P value 0.002 and < 0.001, respectively. In Group B, the most common site of disease failure was distant (9, 53%. Conclusion: PET-CT can be used to evaluate response and as a tool to identify patients at higher risk of distant failure. Further, this could be exploited to

  8. Positron emission tomography in epilepsy

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) was performed with the 18F-fluoro-deoxy-glucose method on 29 patients with epilepsy (generalized epilepsy, 4; partial epilepsy, 24; undetermined type, 1). The subjects were restricted to patients with epilepsy without focal abnormality on X-CT. All the patients with generalized epilepsy showed a normal pattern on PET. Fourteen out of the 24 patients with partial epilepsy and the 1 with epilepsy of undermined type showed focal hypometabolism on PET. The hypometabolic zone was localized in areas including the temporal cortex in 11 patients, frontal in 2 and thalamus in 1. The location of hypometabolic zone and that of interictal paroxysmal activity on EEG were well correlated in most patients. The patients with poorly-controlled seizure showed a higher incidence of PET abnormality (12 out of 13) than those with well-controlled seizures (2 out of 11). The incidence of abnormality on PET and MRI and the location of both abnormality were not necessarily coincident. These results indicated that the PET examination in epilepsy provides valuable information about the location of epileptic focus, and that the findings on PET in patients with partial epilepsy may be one of the good indicators about the intractability of partial epilepsy, and that PET and MRI provide complementary information in the diagnosis of epilepsy. (author)

  9. Perspectives for positron emission tomography with RPCs

    International Nuclear Information System (INIS)

    In this study, we address the feasibility and main properties of a positron emission tomograph (PET) based on RPCs. The concept, making use of the converter-plate principle, takes advantage of the intrinsic layered structure of RPCs and its simple and economic construction. The extremely good time and position resolutions of RPCs also allow the TOF-PET imaging technique to be considered. Monte-Carlo simulations, supported by experimental data, are presented and the main advantages and drawbacks for applications of potential interest are discussed

  10. Simulation of the annihilation emission of galactic positrons

    International Nuclear Information System (INIS)

    Positrons annihilate in the central region of our Galaxy. This has been known since the detection of a strong emission line centered on an energy of 511 keV in the direction of the Galactic center. This gamma-ray line is emitted during the annihilation of positrons with electrons from the interstellar medium. The spectrometer SPI, onboard the INTEGRAL observatory, performed spatial and spectral analyses of the positron annihilation emission. This thesis presents a study of the Galactic positron annihilation emission based on models of the different interactions undergone by positrons in the interstellar medium. The models are relied on our present knowledge of the properties of the interstellar medium in the Galactic bulge, where most of the positrons annihilate, and of the physics of positrons (production, propagation and annihilation processes). In order to obtain constraints on the positrons sources and physical characteristics of the annihilation medium, we compared the results of the models to measurements provided by the SPI spectrometer. (author)

  11. Ventilation/Perfusion Positron Emission Tomography—Based Assessment of Radiation Injury to Lung

    International Nuclear Information System (INIS)

    Purpose: To investigate 68Ga-ventilation/perfusion (V/Q) positron emission tomography (PET)/computed tomography (CT) as a novel imaging modality for assessment of perfusion, ventilation, and lung density changes in the context of radiation therapy (RT). Methods and Materials: In a prospective clinical trial, 20 patients underwent 4-dimensional (4D)-V/Q PET/CT before, midway through, and 3 months after definitive lung RT. Eligible patients were prescribed 60 Gy in 30 fractions with or without concurrent chemotherapy. Functional images were registered to the RT planning 4D-CT, and isodose volumes were averaged into 10-Gy bins. Within each dose bin, relative loss in standardized uptake value (SUV) was recorded for ventilation and perfusion, and loss in air-filled fraction was recorded to assess RT-induced lung fibrosis. A dose-effect relationship was described using both linear and 2-parameter logistic fit models, and goodness of fit was assessed with Akaike Information Criterion (AIC). Results: A total of 179 imaging datasets were available for analysis (1 scan was unrecoverable). An almost perfectly linear negative dose-response relationship was observed for perfusion and air-filled fraction (r2=0.99, P<.01), with ventilation strongly negatively linear (r2=0.95, P<.01). Logistic models did not provide a better fit as evaluated by AIC. Perfusion, ventilation, and the air-filled fraction decreased 0.75 ± 0.03%, 0.71 ± 0.06%, and 0.49 ± 0.02%/Gy, respectively. Within high-dose regions, higher baseline perfusion SUV was associated with greater rate of loss. At 50 Gy and 60 Gy, the rate of loss was 1.35% (P=.07) and 1.73% (P=.05) per SUV, respectively. Of 8/20 patients with peritumoral reperfusion/reventilation during treatment, 7/8 did not sustain this effect after treatment. Conclusions: Radiation-induced regional lung functional deficits occur in a dose-dependent manner and can be estimated by simple linear models with 4D-V/Q PET/CT imaging. These

  12. Ventilation/Perfusion Positron Emission Tomography—Based Assessment of Radiation Injury to Lung

    Energy Technology Data Exchange (ETDEWEB)

    Siva, Shankar, E-mail: shankar.siva@petermac.org [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne (Australia); Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville (Australia); Hardcastle, Nicholas [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne (Australia); Centre for Medical Radiation Physics, University of Wollongong, Wollongong (Australia); Kron, Tomas [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne (Australia); Bressel, Mathias [Department of Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne (Australia); Callahan, Jason [Centre for Molecular Imaging, Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne (Australia); MacManus, Michael P.; Shaw, Mark; Plumridge, Nikki [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne (Australia); Hicks, Rodney J. [Centre for Molecular Imaging, Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne (Australia); Department of Medicine, University of Melbourne, Parkville (Australia); Steinfort, Daniel [Department of Medicine, University of Melbourne, Parkville (Australia); Department of Cancer Medicine, Peter MacCallum Cancer Centre, East Melbourne (Australia); Ball, David L. [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne (Australia); Hofman, Michael S. [Centre for Molecular Imaging, Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne (Australia); Department of Medicine, University of Melbourne, Parkville (Australia)

    2015-10-01

    Purpose: To investigate {sup 68}Ga-ventilation/perfusion (V/Q) positron emission tomography (PET)/computed tomography (CT) as a novel imaging modality for assessment of perfusion, ventilation, and lung density changes in the context of radiation therapy (RT). Methods and Materials: In a prospective clinical trial, 20 patients underwent 4-dimensional (4D)-V/Q PET/CT before, midway through, and 3 months after definitive lung RT. Eligible patients were prescribed 60 Gy in 30 fractions with or without concurrent chemotherapy. Functional images were registered to the RT planning 4D-CT, and isodose volumes were averaged into 10-Gy bins. Within each dose bin, relative loss in standardized uptake value (SUV) was recorded for ventilation and perfusion, and loss in air-filled fraction was recorded to assess RT-induced lung fibrosis. A dose-effect relationship was described using both linear and 2-parameter logistic fit models, and goodness of fit was assessed with Akaike Information Criterion (AIC). Results: A total of 179 imaging datasets were available for analysis (1 scan was unrecoverable). An almost perfectly linear negative dose-response relationship was observed for perfusion and air-filled fraction (r{sup 2}=0.99, P<.01), with ventilation strongly negatively linear (r{sup 2}=0.95, P<.01). Logistic models did not provide a better fit as evaluated by AIC. Perfusion, ventilation, and the air-filled fraction decreased 0.75 ± 0.03%, 0.71 ± 0.06%, and 0.49 ± 0.02%/Gy, respectively. Within high-dose regions, higher baseline perfusion SUV was associated with greater rate of loss. At 50 Gy and 60 Gy, the rate of loss was 1.35% (P=.07) and 1.73% (P=.05) per SUV, respectively. Of 8/20 patients with peritumoral reperfusion/reventilation during treatment, 7/8 did not sustain this effect after treatment. Conclusions: Radiation-induced regional lung functional deficits occur in a dose-dependent manner and can be estimated by simple linear models with 4D-V/Q PET

  13. Bioimpedance-based respiratory gating method for oncologic positron emission tomography (PET) imaging with first clinical results

    International Nuclear Information System (INIS)

    Respiratory motion may cause significant image artefacts in positron emission tomography/computed tomography (PET/CT) imaging. This study introduces a new bioimpedance-based gating method for minimizing respiratory artefacts. The method was studied in 12 oncologic patients by evaluating the following three parameters: maximum metabolic activity of radiopharmaceutical accumulations, the size of these targets as well as their target-to-background ratio. The bioimpedance-gated images were compared with non-gated images and images that were gated with a reference method, chest wall motion monitoring by infrared camera. The bioimpedance method showed clear improvement as increased metabolic activity and decreased target volume compared to non-gated images and produced consistent results with the reference method. Thus, the method may have great potential in the future of respiratory gating in nuclear medicine imaging.

  14. Bioimpedance-based respiratory gating method for oncologic positron emission tomography (PET) imaging with first clinical results

    Science.gov (United States)

    Koivumäki, T.; Vauhkonen, M.; Teuho, J.; Teräs, M.; Hakulinen, M. A.

    2013-04-01

    Respiratory motion may cause significant image artefacts in positron emission tomography/computed tomography (PET/CT) imaging. This study introduces a new bioimpedance-based gating method for minimizing respiratory artefacts. The method was studied in 12 oncologic patients by evaluating the following three parameters: maximum metabolic activity of radiopharmaceutical accumulations, the size of these targets as well as their target-to-background ratio. The bioimpedance-gated images were compared with non-gated images and images that were gated with a reference method, chest wall motion monitoring by infrared camera. The bioimpedance method showed clear improvement as increased metabolic activity and decreased target volume compared to non-gated images and produced consistent results with the reference method. Thus, the method may have great potential in the future of respiratory gating in nuclear medicine imaging.

  15. Cyclotron, positrons and PET [positron emission tomography]. An overview

    International Nuclear Information System (INIS)

    PET (positron emission tomography) is a powerful new scientific tool which is capable of revealing biochemical transformations while they are occurring in the brain and other organs in the living human body. The application of PET to problems in biology and medicine is dominated by the short half-life of the isotopes used to prepare the radiotracers. The most commonly used positron emitting isotopes are carbon-11, fluorine-18, nitrogen-13, and oxygen-15 which have half-lives of 20.4, 110, 10 and 2 minutes, respectively. Their incorporation into radiotracers having diverse chemical structures and biochemical specificities has allowed the study of blood flow, sugar metabolism, oxygen metabolism, neurotransmission, enzyme activity and binding sites for therapeutic drugs and substances of abuse. PET research is most commonly carried out at a Cyclotron-PET Center (cyclotron, positron emission tomography, chemistry laboratory) where the short-lived isotopes can be produced and used efficiently. The number of Cyclotron-PET Centers has grown from 4 in 1976 to several dozen in 1988 and the number is expected to double in the next five years attesting to the vitality of the field and the current and anticipated contributions to research in biology and medicine

  16. The introduction of positron emission tomography in Australia

    International Nuclear Information System (INIS)

    Positron Emission Tomography (PET) is a relatively new medical imaging modality based on images of the distribution of positron emitting radioisotopes in the human body. A PET scan can non-invasively provide quantitative information on the in vivo function performance of an organ, part thereof, or a bodily process. Two PET centres currently being established in Melbourne and in Sydney are introduced. 18 refs., 1 tab., 5 figs

  17. Ionization and positron emission in giant quasiatoms

    International Nuclear Information System (INIS)

    Electron excitation processes in superheavy quasiatoms are treated within a relativistic framework. Theoretical results on K-hole production rates as well as delta-electron and positron spectra are compared with experimental data. It is demonstrated that the study of heavy ion collisions with nuclear time delay promises a signature for the spontaneous positron formation in overcritical systems. Corresponding experimental results are confronted with our theoretical hypothesis. Recent speculations on the origin of the observed peak structures in positron spectra are critically reviewed. Atomic excitations are also employed to obtain information on the course of a nuclear reaction. Using a semiclassical picture we calculate the emission of delta-electrons and positrons in deep-inelastic nuclear reactions. Furthermore some consequences of conversion processes in giant systems are investigated. (orig.)

  18. Positron emission tomography imaging of gene expression

    International Nuclear Information System (INIS)

    The merging of molecular biology and nuclear medicine is developed into molecular nuclear medicine. Positron emission tomography (PET) of gene expression in molecular nuclear medicine has become an attractive area. Positron emission tomography imaging gene expression includes the antisense PET imaging and the reporter gene PET imaging. It is likely that the antisense PET imaging will lag behind the reporter gene PET imaging because of the numerous issues that have not yet to be resolved with this approach. The reporter gene PET imaging has wide application into animal experimental research and human applications of this approach will likely be reported soon

  19. Positron emission tomography: radioisotope and radiopharmaceutical production

    International Nuclear Information System (INIS)

    A Centre for Positron Emission Tomography (PET) has been operational within the Department of Nuclear Medicine at the Austin and Repatriation Medical Centre (A and RMC) in Melbourne for seven years. PET is a non-invasive imaging technique based on the use of biologically relevant compounds labelled with short-lived positron-emitting radionuclides such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18. The basic facility consists of a medical cyclotron (10 MeV proton and 5 MeV deuteron), six lead-shielded hot cells with associated radiochemistry facilities, radiopharmacy and a whole body PET scanner. A strong radiolabelling development program, including the production of 15O-oxygen, 15O-carbon monoxide, 15O-carbon dioxide, 15O-water, 13N-ammonia, 18F-FDG, 18F-FMISO, 11C-SCH23390 and 11C-flumazenil has been pursued to support an ambitious clinical and research program in neurology, oncology, cardiology and psychiatry. Copyright (1999) Australasian Physical and Engineering Sciences in Medicine and the College of Biomedical Engineers

  20. Motion correction in thoracic positron emission tomography

    CERN Document Server

    Gigengack, Fabian; Dawood, Mohammad; Schäfers, Klaus P

    2015-01-01

    Respiratory and cardiac motion leads to image degradation in Positron Emission Tomography (PET), which impairs quantification. In this book, the authors present approaches to motion estimation and motion correction in thoracic PET. The approaches for motion estimation are based on dual gating and mass-preserving image registration (VAMPIRE) and mass-preserving optical flow (MPOF). With mass-preservation, image intensity modulations caused by highly non-rigid cardiac motion are accounted for. Within the image registration framework different data terms, different variants of regularization and parametric and non-parametric motion models are examined. Within the optical flow framework, different data terms and further non-quadratic penalization are also discussed. The approaches for motion correction particularly focus on pipelines in dual gated PET. A quantitative evaluation of the proposed approaches is performed on software phantom data with accompanied ground-truth motion information. Further, clinical appl...

  1. Advanced instrumentation for Positron Emission Tomography

    International Nuclear Information System (INIS)

    This paper summarizes the physical processes and medical science goals that underly modern instrumentation design for Positron Emission Tomography. The paper discusses design factors such as detector material, crystalphototube coupling, shielding geometry, sampling motion, electronics design, time-of-flight, and the interrelationships with quantitative accuracy, spatial resolution, temporal resolution, maximum data rates, and cost. 71 refs., 3 figs., 3 tabs

  2. Advanced Instrumentation for Positron Emission Tomography [PET

    Science.gov (United States)

    Derenzo, S. E.; Budinger, T. F.

    1985-04-01

    This paper summarizes the physical processes and medical science goals that underlay modern instrumentation design for Positron Emission Tomography. The paper discusses design factors such as detector material, crystalphototube coupling, shielding geometry, sampling motion, electronics design, time-of-flight, and the interrelationships with quantitative accuracy, spatial resolution, temporal resolution, maximum data rates, and cost.

  3. Evaluation of contrast reproduction method based on the anatomical guidance of the cerebral images reconstruction in positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography is a medical imaging modality providing in-vivo volumetric images of functional processes of the human body, which is used for the diagnosis and the following of neuro degenerative diseases. PET efficiency is however limited by its poor spatial resolution, which generates a decrease of the image local contrast and leads to an under-estimation of small cerebral structures involved in the degenerative mechanism of those diseases. This so-called partial volume effect degradation is usually corrected in a post-reconstruction processing framework through the use of anatomical information, whose spatial resolution allows a better discrimination between functional tissues. However, this kind of method has the major drawback of being very sensitive to the residual mismatches on the anatomical information processing. We developed in this thesis an alternative methodology to compensate for the degradation, by incorporating in the reconstruction process both a model of the system impulse response and an anatomically-based image prior constraint. This methodology was validated by comparison with a post-reconstruction correction strategy, using data from an anthropomorphic phantom acquisition and then we evaluated its robustness to the residual mismatches through a realistic Monte Carlo simulation corresponding to a cerebral exam. The proposed algorithm was finally applied to clinical data reconstruction. (author)

  4. Development of a non-delay line constant fraction discriminator based on the Padé approximant for time-of-flight positron emission tomography scanners

    International Nuclear Information System (INIS)

    In positron emission tomography, the constant fraction discriminator (CFD) circuit is used to acquire accurate arrival times for the annihilation photons with minimum sensitivity to time walk. As the number of readout channels increases, it becomes difficult to use conventional CFDs because of the large amount of space required for the delay line part of the circuit. To make the CFD compact, flexible, and easily controllable, a non-delay-line CFD based on the Padé approximant is proposed. The non-delay-line CFD developed in this study is shown to have timing performance that is similar to that of a conventional delay-line-based CFD in terms of the coincidence resolving time of a fast photomultiplier tube detector. This CFD can easily be applied to various positron emission tomography system designs that contain high-density detectors with multi-channel structures

  5. ATLAAS: an automatic decision tree-based learning algorithm for advanced image segmentation in positron emission tomography

    Science.gov (United States)

    Berthon, Beatrice; Marshall, Christopher; Evans, Mererid; Spezi, Emiliano

    2016-07-01

    Accurate and reliable tumour delineation on positron emission tomography (PET) is crucial for radiotherapy treatment planning. PET automatic segmentation (PET-AS) eliminates intra- and interobserver variability, but there is currently no consensus on the optimal method to use, as different algorithms appear to perform better for different types of tumours. This work aimed to develop a predictive segmentation model, trained to automatically select and apply the best PET-AS method, according to the tumour characteristics. ATLAAS, the automatic decision tree-based learning algorithm for advanced segmentation is based on supervised machine learning using decision trees. The model includes nine PET-AS methods and was trained on a 100 PET scans with known true contour. A decision tree was built for each PET-AS algorithm to predict its accuracy, quantified using the Dice similarity coefficient (DSC), according to the tumour volume, tumour peak to background SUV ratio and a regional texture metric. The performance of ATLAAS was evaluated for 85 PET scans obtained from fillable and printed subresolution sandwich phantoms. ATLAAS showed excellent accuracy across a wide range of phantom data and predicted the best or near-best segmentation algorithm in 93% of cases. ATLAAS outperformed all single PET-AS methods on fillable phantom data with a DSC of 0.881, while the DSC for H&N phantom data was 0.819. DSCs higher than 0.650 were achieved in all cases. ATLAAS is an advanced automatic image segmentation algorithm based on decision tree predictive modelling, which can be trained on images with known true contour, to predict the best PET-AS method when the true contour is unknown. ATLAAS provides robust and accurate image segmentation with potential applications to radiation oncology.

  6. Positron emission tomography of the lung

    International Nuclear Information System (INIS)

    Positron emission tomography enables the distribution of positron emitting isotopes to be imaged in a transverse plane through the body and the regional concentration of the isotope to be measured quantitatively. This thesis reports some applications of positron emission tomography to studies of pulmonary pathophysiology. Measurements in lung phantoms showed that regional lung density could be measured from a transmission tomogram obtained with an external source of positron emitting isotope. The regional, fractional blood volume was measured after labelling the blood with carbon-11-monoxide. Regional extravascular lung density (lung tissue and interstitial water per unit thoracic volume) was obtained by subtracting fractional blood volume from lung density. Measurements in normal subjects revealed large regional variations in lung density and fractional blood volume in the supine posture. Extravascular lung density showed a more uniform distribution. The technique has been used to study patients with chronic interstitial pulmonary oedema, pulmonary sarcoidosis and fibrosis, pulmonary arterial hypertension and patients with intracardiac, left-to-right shunt. Tomographic measurements of pulmonary tissue concentration of radionuclides are difficult, since corrections for the blood content and the inflation of the lung must be applied. A simultaneous measurement of lung density and fractional blood volume allows such corrections to be made and the extravascular tracer concentration to be calculated. This has been applied to measurements of the tissue penetration of carbon-11-labelled erythromycin in patients with lobar pneumonia. (author)

  7. Incidental colorectal polyps in positron emission tomography

    International Nuclear Information System (INIS)

    Fluorodeoxy glucose positron emission tomography/computed tomography (FDG PET/CT) is increasingly being used for diagnosing various malignancies and surveillance of cancer recurrence, staging and screening in high-risk individuals. Due to its high sensitivity in picking up small dysplastic lesions, incidental lesions are detected frequently. We present two patients who underwent PET CT as part of cancer screening and were incidentally detected with adenomatous colonic polyps. Colonoscopy and biopsy confirmed the diagnosis

  8. Positron emission tomography (PET) for cholangiocarcinoma

    OpenAIRE

    Breitenstein, S; Apestegui, C.; Clavien, P.-A.

    2008-01-01

    The combination of positron emission tomography (PET) with computed tomography (PET-CT) provides simultaneous metabolic and anatomic information on tumors in the same imaging session. Sensitivity of PET/PET-CT is higher for intrahepatic (>90%) than for extrahepatic cholangiocarcinoma (CCA) (about 60%). The detection rate of distant metastasis is 100%. PET, and particularly PET-CT, improves the results and impacts on the oncological management in CCA compared with other imaging modalities. The...

  9. Resistive plate chambers in positron emission tomography

    Science.gov (United States)

    Crespo, Paulo; Blanco, Alberto; Couceiro, Miguel; Ferreira, Nuno C.; Lopes, Luís; Martins, Paulo; Ferreira Marques, Rui; Fonte, Paulo

    2013-07-01

    Resistive plate chambers (RPC) were originally deployed for high energy physics. Realizing how their properties match the needs of nuclear medicine, a LIP team proposed applying RPCs to both preclinical and clinical positron emission tomography (RPC-PET). We show a large-area RPC-PET simulated scanner covering an axial length of 2.4m —slightly superior to the height of the human body— allowing for whole-body, single-bed RPC-PET acquisitions. Simulations following NEMA (National Electrical Manufacturers Association, USA) protocols yield a system sensitivity at least one order of magnitude larger than present-day, commercial PET systems. Reconstruction of whole-body simulated data is feasible by using a dedicated, direct time-of-flight-based algorithm implemented onto an ordered subsets estimation maximization parallelized strategy. Whole-body RPC-PET patient images following the injection of only 2mCi of 18-fluorodesoxyglucose (FDG) are expected to be ready 7 minutes after the 6 minutes necessary for data acquisition. This compares to the 10-20mCi FDG presently injected for a PET scan, and to the uncomfortable 20-30minutes necessary for its data acquisition. In the preclinical field, two fully instrumented detector heads have been assembled aiming at a four-head-based, small-animal RPC-PET system. Images of a disk-shaped and a needle-like 22Na source show unprecedented sub-millimeter spatial resolution.

  10. Physiologic signal detection in positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography enables the noninvasive quantification in vivo of three-dimensional radionuclide distributions throughout the human body. Estimation of neurotransmitter and receptor function is performed through the application of tracer kinetic models and non-linear multiple regression parameter estimation methods. These quantitative estimates are often limited by the interaction between imaging characteristics of the PET scanner and the three-dimensional radionuclide distribution within the organ of interest. In order to assess the potential of PET to detect subtle changes in the function of the central nervous system, a three-dimensional PET simulation procedure based upon a digital brain phantom and tomograph detector response functions has been performed. Radiopharmaceutical kinetics for individual structures of the brain phantom (cortex, white matter, basal ganglia, etc.) have been assigned based upon in vitro autoradiography of human postmortem tissue and animal biodistribution studies. The recovery of the PET signals which originate from anatomic structures of interest has been evaluated for studies of the benzodiazepine, muscarinic, opiate, and GABA systems of the human brain. Typical results and the limitations of signal detection in PET neurotransmitter and receptor studies are discussed

  11. Amplitude-based optimal respiratory gating in positron emission tomography in patients with primary lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Grootjans, Willem; Meeuwis, Antoi P.W.; Vos, Charlotte S. van der; Gotthardt, Martin; Oyen, Wim J.G.; Visser, Eric P. [Radboud University Medical Center, Department of Radiology and Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Geus-Oei, Lioe-Fee de [Radboud University Medical Center, Department of Radiology and Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); University of Twente, MIRA Institute for Biomedical Technology and Technical Medicine, Enschede (Netherlands)

    2014-12-15

    Respiratory motion during PET imaging introduces quantitative and diagnostic inaccuracies, which may result in non-optimal patient management. This study investigated the effects of respiratory gating on image quantification using an amplitude-based optimal respiratory gating (ORG) algorithm. Whole body FDG-PET/CT was performed in 66 lung cancer patients. The respiratory signal was obtained using a pressure sensor integrated in an elastic belt placed around the patient's thorax. ORG images were reconstructed with 50 %, 35 %, and 20 % of acquired PET data (duty cycle). Lesions were grouped into anatomical locations. Differences in lesion volume between ORG and non-gated images, and mean FDG-uptake (SUV{sub mean}) were calculated. Lesions in the middle and lower lobes demonstrated a significant SUV{sub mean} increase for all duty cycles and volume decrease for duty cycles of 35 % and 20 %. Significant increase in SUV{sub mean} and decrease in volume for lesions in the upper lobes were observed for a 20 % duty cycle. The SUV{sub mean} increase for central lesions was significant for all duty cycles, whereas a significant volume decrease was observed for a duty cycle of 20 %. This study implies that ORG could influence clinical PET imaging with respect to response monitoring and radiotherapy planning. (orig.)

  12. Amplitude-based optimal respiratory gating in positron emission tomography in patients with primary lung cancer

    International Nuclear Information System (INIS)

    Respiratory motion during PET imaging introduces quantitative and diagnostic inaccuracies, which may result in non-optimal patient management. This study investigated the effects of respiratory gating on image quantification using an amplitude-based optimal respiratory gating (ORG) algorithm. Whole body FDG-PET/CT was performed in 66 lung cancer patients. The respiratory signal was obtained using a pressure sensor integrated in an elastic belt placed around the patient's thorax. ORG images were reconstructed with 50 %, 35 %, and 20 % of acquired PET data (duty cycle). Lesions were grouped into anatomical locations. Differences in lesion volume between ORG and non-gated images, and mean FDG-uptake (SUVmean) were calculated. Lesions in the middle and lower lobes demonstrated a significant SUVmean increase for all duty cycles and volume decrease for duty cycles of 35 % and 20 %. Significant increase in SUVmean and decrease in volume for lesions in the upper lobes were observed for a 20 % duty cycle. The SUVmean increase for central lesions was significant for all duty cycles, whereas a significant volume decrease was observed for a duty cycle of 20 %. This study implies that ORG could influence clinical PET imaging with respect to response monitoring and radiotherapy planning. (orig.)

  13. Target Volume Delineation in Dynamic Positron Emission Tomography Based on Time Activity Curve Differences

    Science.gov (United States)

    Teymurazyan, Artur

    Tumor volume delineation plays a critical role in radiation treatment planning and simulation, since inaccurately defined treatment volumes may lead to the overdosing of normal surrounding structures and potentially missing the cancerous tissue. However, the imaging modality almost exclusively used to determine tumor volumes, X-ray Computed Tomography (CT), does not readily exhibit a distinction between cancerous and normal tissue. It has been shown that CT data augmented with PET can improve radiation treatment plans by providing functional information not available otherwise. Presently, static PET scans account for the majority of procedures performed in clinical practice. In the radiation therapy (RT) setting, these scans are visually inspected by a radiation oncologist for the purpose of tumor volume delineation. This approach, however, often results in significant interobserver variability when comparing contours drawn by different experts on the same PET/CT data sets. For this reason, a search for more objective contouring approaches is underway. The major drawback of conventional tumor delineation in static PET images is the fact that two neighboring voxels of the same intensity can exhibit markedly different overall dynamics. Therefore, equal intensity voxels in a static analysis of a PET image may be falsely classified as belonging to the same tissue. Dynamic PET allows the evaluation of image data in the temporal domain, which often describes specific biochemical properties of the imaged tissues. Analysis of dynamic PET data can be used to improve classification of the imaged volume into cancerous and normal tissue. In this thesis we present a novel tumor volume delineation approach (Single Seed Region Growing algorithm in 4D (dynamic) PET or SSRG/4D-PET) in dynamic PET based on TAC (Time Activity Curve) differences. A partially-supervised approach is pursued in order to allow an expert reader to utilize the information available from other imaging

  14. Beyond FDG positron emission tomography imaging

    International Nuclear Information System (INIS)

    At present, positron emission tomography/computed tomography (PET/CT) is one of the most rapidly growing areas of medical imaging, with many applications in the clinical management of patients with cancer. Although ((18)F) fluorodeoxyglucose (FDG)-PET/CT imaging provides high specificity and sensitivity in several kinds of cancer and has many applications, it is important to recognize that FDG is not a 'specific' radiotracer for imaging malignant disease. Highly 'tumor-specific' PET radiopharmaceuticals are essential to meet the growing demand of radioisotope-based molecular imaging technology. C-11 Methionine PET has been used to better define the radiotherapy field both for CNS tumors and head and neck (H and N) tumors to localize the most metabolic area inside a brain mass to guide the biopsy or in early evaluation of radiotherapy effect on H and N cancer. Flurodihydroxyphenylalanine (FDOPA) is an aromatic amino acid labelled with 18F. Besides it has also been introduced into oncological practice, in particular for malignant tumors of neural crest origin

  15. Iterative image reconstruction for positron emission tomography based on a detector response function estimated from point source measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tohme, Michel S; Qi Jinyi [Department of Biomedical Engineering, University of California, Davis, CA 95616 (United States)], E-mail: qi@ucdavis.edu

    2009-06-21

    The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of a sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can easily be applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3 x 3 line phantom, an ultra-micro resolution phantom and a {sup 22}Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

  16. Iterative Image Reconstruction for Positron Emission Tomography Based on Detector Response Function Estimated from Point Source Measurements

    Science.gov (United States)

    Tohme, Michel S.; Qi, Jinyi

    2009-01-01

    The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can be easily applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2-D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3-by-3 line phantom, an ultra-micro resolution phantom, and a 22Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

  17. Iterative image reconstruction for positron emission tomography based on a detector response function estimated from point source measurements

    Science.gov (United States)

    Tohme, Michel S.; Qi, Jinyi

    2009-06-01

    The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of a sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can easily be applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3 × 3 line phantom, an ultra-micro resolution phantom and a 22Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

  18. Are We Ready for Positron Emission Tomography/Computed Tomography-based Target Volume Definition in Lymphoma Radiation Therapy?

    International Nuclear Information System (INIS)

    Fluorine-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) has become indispensable for the clinical management of lymphomas. With consistent evidence that it is more accurate than anatomic imaging in the staging and response assessment of many lymphoma subtypes, its utility continues to increase. There have therefore been efforts to incorporate PET/CT data into radiation therapy decision making and in the planning process. Further, there have also been studies investigating target volume definition for radiation therapy using PET/CT data. This article will critically review the literature and ongoing studies on the above topics, examining the value and methods of adding PET/CT data to the radiation therapy treatment algorithm. We will also discuss the various challenges and the areas where more evidence is required.

  19. Positron emission particle tracking-Application and labelling techniques

    Institute of Scientific and Technical Information of China (English)

    David J.Parker; Xianfeng Fan

    2008-01-01

    The positron emission particle tracking (PEPT) technique has been widely used in science and engineering to obtain detailed information on the motion and flow fields of fluids or granular materials in multiphase systems, for example, fluids in rock cracks, chemical reactors and food processors; dynamic behaviour of granular materials in chemical reactors, granulators, mixers, dryers, rotating kilns and ball mills. The information obtained by the PEPT technique can be used to optimise the design, operational conditions for a wide range of industrial process systems, and to evaluate modelling work. The technique is based on tracking radioactively labelled particles (up to three particles) by detecting the pairs of back-to-back 511 ke V -γ-rays arising from annihilation of emitted positrons. It therefore involves a positron camera, location algorithms for calculating the tracer location and speed, and tracer labelling techniques. This paper will review the particle tracking technique from tracking algorithm, tracer labelling to their application.

  20. Voxel imaging pet pathfinder: a novel approach to positron emission tomography based on room temperature pixelated CdTe detector

    OpenAIRE

    Mikhaylova, Ekaterina

    2014-01-01

    El objetivo principal de esta investigación es la simulación y la evaluación de un nuevo concepto de escáner de tomografía por emisión de positrones (PET) basado en un detector pixelado de CdTe en el marco del proyecto “Voxel Imaging PET (VIP) Pathfinder”. El diseño se ha simulado con el programa “GEANT4-based Architecture for Medicine-Oriented Simulations” (GAMOS). El sistema se ha examinado siguiendo las prescripciones de los protocolos NEMA para la evaluación de los dispositivos PET. Varia...

  1. Voxel imaging pet pathfinder: a novel approach to positron emission tomography based on room temperature pixelated CdTe detector

    OpenAIRE

    Mikhaylova, Ekaterina; Fernandez Sanchez, Enrique

    2014-01-01

    El objetivo principal de esta investigación es la simulación y la evaluación de un nuevo concepto de escáner de tomografía por emisión de positrones (PET) basado en un detector pixelado de CdTe en el marco del proyecto "Voxel Imaging PET (VIP) Pathfinder". El diseño se ha simulado con el programa "GEANT4-based Architecture for Medicine-Oriented Simulations" (GAMOS). El sistema se ha examinado siguiendo las prescripciones de los protocolos NEMA para la evaluación de los dispositivos PET. Varia...

  2. Applications of nucleoside-based molecular probes for the in vivo assessment of tumour biochemistry using positron emission tomography (PET

    Directory of Open Access Journals (Sweden)

    Leonard I. Wiebe

    2007-05-01

    Full Text Available Positron emission tomography (PET is a non-invasive nuclear imaging technique. In PET, radiolabelled molecules decay by positron emission. The gamma rays resulting from positron annihilation are detected in coincidence and mapped to produce three dimensional images of radiotracer distribution in the body. Molecular imaging with PET refers to the use of positron-emitting biomolecules that are highly specific substrates for target enzymes, transport proteins or receptor proteins. Molecular imaging with PET produces spatial and temporal maps of the target-related processes. Molecular imaging is an important analytical tool in diagnostic medical imaging, therapy monitoring and the development of new drugs. Molecular imaging has its roots in molecular biology. Originally, molecular biology meant the biology of gene expression, but now molecular biology broadly encompasses the macromolecular biology and biochemistry of proteins, complex carbohydrates and nucleic acids. To date, molecular imaging has focused primarily on proteins, with emphasis on monoclonal antibodies and their derivative forms, small-molecule enzyme substrates and components of cell membranes, including transporters and transmembrane signalling elements. This overview provides an introduction to nucleosides, nucleotides and nucleic acids in the context of molecular imaging.A tomografia por emissão de pósitrons (TEP é uma técnica de imagem não invasiva da medicina nuclear. A TEP utiliza moléculas marcadas com emissores de radiação beta positiva (pósitrons. As radiações gama medidas que resultam do aniquilamento dos pósitrons são detectadas por um sistema de coincidência e mapeadas para produzir uma imagem tridimensional da distribuição do radiotraçador no corpo. A imagem molecular com TEP refere-se ao uso de biomoléculas marcadas com emissor de pósitron que são substratos altamente específicos para alvos como enzimas, proteínas transportadoras ou receptores prot

  3. Positron Emission Tomography: Its 65 years

    Science.gov (United States)

    Del Guerra, A.; Belcari, N.; Bisogni, M.

    2016-04-01

    Positron Emission Tomography (PET) is a well-established imaging technique for in vivo molecular imaging. In this review after a brief history of PET there are presented its physical principles and the technology that has been developed for bringing PET from a bench experiment to a clinical indispensable instrument. The limitations and performance of the PET tomographs are discussed, both as for the hardware and software aspects. The status of art of clinical, pre-clinical and hybrid scanners (, PET/CT and PET/MR) is reported. Finally the actual trend and the recent and future technological developments are fully illustrated.

  4. Positron emission tomography of FDG in schizophrenia

    International Nuclear Information System (INIS)

    The use of the Donner dynamic positron emission tomograph to study fluorodeoxyglucose labelled 18F uptake in the brain of six patients with schizophrenia is reported. The glucose metabolic rate and the local cerebral metabolic rate were calculated. The dynamic brain uptake data and the blood input function were used to calculate rate constants by an iterative least squares fitting program for all regions of interest chosen in the brain. Although the number of patients was small, differences in k3 were statistically significant in several brain regions compared with normal controls

  5. Positron Emission Tomography Imaging of Pancreatic Cancer

    Directory of Open Access Journals (Sweden)

    Saravanan Kokila Krishnamoorthy

    2014-03-01

    Full Text Available Positron emission tomography (PET using 18F-fluorodeoxyglucose (FDG is increasingly used for the staging of solidmalignancies, including lung and esophagus. However, controversy still exists in relation to the application of PET inpancreatic cancer. The authors review seven studies (Abstracts #183, #189, #190, #254, #357, #375, #378 presented at the2014 ASCO Gastrointestinal Cancers Symposium and discuss on the role of PET in this disease. As the limitations of theResponse Evaluation Criteria In Solid Tumors (RECIST continue to become evident, FDG-PET may identify changes in themetabolic activity within pancreatic adenocarcinoma, and can provide both diagnostic and prognostic information.

  6. Radioactive labeling of defined HPMA-based polymeric structures using [18F]FETos for in vivo imaging by positron emission tomography

    DEFF Research Database (Denmark)

    Herth, Matthias Manfred; Barz, Matthias; Moderegger, Dorothea;

    2009-01-01

    During the last decades polymer-based nanomedicine has turned out to be a promising tool in modern pharmaceutics. The following article describes the synthesis of well-defined random and block copolymers by RAFT polymerization with potential medical application. The polymers have been labeled with...... isotonic buffer solution. Any decomposition could be detected within 2 h. To determine the in vivo fate of (18)F-labeled HPMA polymers, preliminary small animal positron emission tomography (PET) experiments were performed in healthy rats, demonstrating the renal clearance of low molecular weight polymers...

  7. Shielding design for positron emission tomography facility

    International Nuclear Information System (INIS)

    With the recent advent of readily available tracer isotopes, there has been marked increase in the number of hospital-based and free-standing positron emission tomography (PET) clinics. PET facilities employ relatively large activities of high-energy photon emitting isotopes, which can be dangerous to the health of humans and animals. This coupled with the current dose limits for radiation worker and members of the public can result in shielding requirements. This research contributes to the calculation of the appropriate shielding to keep the level of radiation within an acceptable recommended limit. Two different methods were used including measurements made at selected points of an operating PET facility and computer simulations by using Monte Carlo Transport Code. The measurements mainly concerned the radiation exposure at different points around facility using the survey meter detectors and Thermoluminescent Dosimeters (TLD). Then the set of manual calculation procedures were used to estimate the shielding requirements for a newly built PEF facility. The results from the measurement and the computer simulation were compared to the results obtained from the set manual calculation procedure. In general, the estimated weekly dose at the points of interest is lower than the regulatory limits for the little company of Mary Hospital. Furthermore, the density and the HVL for normal strength concrete and clay bricks are almost similar. In conclusion, PET facilities present somewhat different design requirements and are more likely to require additional radiation shielding. Therefore, existing shields at the little Company of Mary Hospital are in general found to be adequate and satisfactory and additional shielding was found necessary at the new PET facility in the department of Nuclear Medicine of the Dr. George Mukhari Hospital. By use of appropriate design, by implying specific shielding requirements and by maintaining good operating practices, radiation doses to

  8. Liquid Xenon Detectors for Positron Emission Tomography

    OpenAIRE

    Miceli, A.; Amaudruz, P.; Benard, F.; Bryman, D. A.; Kurchaninov, L.; Martin, J. P.; Muennich, A.; Retiere, F.; Ruth, T J.; Sossi, V.; A.J. Stoessl

    2011-01-01

    PET is a functional imaging technique based on detection of annihilation photons following beta decay producing positrons. In this paper, we present the concept of a new PET system for preclinical applications consisting of a ring of twelve time projection chambers filled with liquid xenon viewed by avalanche photodiodes. Simultaneous measurement of ionization charge and scintillation light leads to a significant improvement to spatial resolution, image quality, and sensitivity. Simulated per...

  9. A novel clustering approach to positron emission particle tracking

    Science.gov (United States)

    Wiggins, Cody; Santos, Roque; Ruggles, Arthur

    2016-03-01

    A novel approach to positron emission particle tracking is presented based on determining regions of space with high density of line of response crossing via clustering. The method is shown to be able to accurately track multiple particles in systems where the number of particles is unknown and in which particles can enter and leave the field of view of the scanning system. This method is explored in various environments and its parametric dependence is studied.

  10. Microfluidics for Positron Emission Tomography (PET) Imaging Probe Development

    OpenAIRE

    Wang, Ming-Wei; Lin, Wei-Yu; Liu, Kan; Masterman-Smith, Michael; Shen, Clifton Kwang-Fu

    2010-01-01

    Due to increased needs for Positron Emission Tomography (PET) scanning, high demands for a wide variety of radiolabeled compounds will have to be met by exploiting novel radiochemistry and engineering technologies to improve the production and development of PET probes. The application of microfluidic reactors to perform radiosyntheses is currently attracting a great deal of interest because of their potential to deliver many advantages over conventional labeling systems. Microfluidic-based r...

  11. Positron emission tomography tracers for imaging angiogenesis

    International Nuclear Information System (INIS)

    Position emission tomography imaging of angiogenesis may provide non-invasive insights into the corresponding molecular processes and may be applied for individualized treatment planning of antiangiogenic therapies. At the moment, most strategies are focusing on the development of radiolabelled proteins and antibody formats targeting VEGF and its receptor or the ED-B domain of a fibronectin isoform as well as radiolabelled matrix metalloproteinase inhibitors or αvβ3 integrin antagonists. Great efforts are being made to develop suitable tracers for different target structures. All of the major strategies focusing on the development of radiolabelled compounds for use with positron emission tomography are summarized in this review. However, because the most intensive work is concentrated on the development of radiolabelled RGD peptides for imaging αvβ3 expression, which has successfully made its way from bench to bedside, these developments are especially emphasized. (orig.)

  12. [Basic principles of 18F-fluorodeoxyglucose positron emission tomography].

    Science.gov (United States)

    Standke, R

    2002-01-01

    Positron emission tomography uses photons to receive regional information about dynamic, physiologic, and biochemical processes in the living body. A positron decay is measured indirectly by the simultaneous registration of both gamma rays created by the annihilation. The event is counted, if two directly opposite located detectors register gamma rays in coincidence. Unfortunately the detectors of a positron emission tomography system do not register only true coincident events. There are also scattered and random coincidences. Different types of positron tomographs are presented and scintillation crystals, which are in use for positron emission tomography are discussed. The 2D- and 3D-acquisition methods are described as well as preprocessing methods, such as correction for attenuation, scatter and dead time. For quantification the relative parameter standard uptake value (SUV) is explained. Finally hybrid systems, such as combined positron emission tomography/computed tomography scanners and the use of computed tomography data for attenuation correction are introduced. PMID:12506765

  13. Positron emission tomography/computed tomography.

    Science.gov (United States)

    Townsend, David W

    2008-05-01

    Accurate anatomical localization of functional abnormalities obtained with the use of positron emission tomography (PET) is known to be problematic. Although tracers such as (18)F-fluorodeoxyglucose ((18)F-FDG) visualize certain normal anatomical structures, the spatial resolution is generally inadequate for accurate anatomic localization of pathology. Combining PET with a high-resolution anatomical imaging modality such as computed tomography (CT) can resolve the localization issue as long as the images from the two modalities are accurately coregistered. However, software-based registration techniques have difficulty accounting for differences in patient positioning and involuntary movement of internal organs, often necessitating labor-intensive nonlinear mapping that may not converge to a satisfactory result. Acquiring both CT and PET images in the same scanner obviates the need for software registration and routinely provides accurately aligned images of anatomy and function in a single scan. A CT scanner positioned in line with a PET scanner and with a common patient couch and operating console has provided a practical solution to anatomical and functional image registration. Axial translation of the couch between the 2 modalities enables both CT and PET data to be acquired during a single imaging session. In addition, the CT images can be used to generate essentially noiseless attenuation correction factors for the PET emission data. By minimizing patient movement between the CT and PET scans and accounting for the axial separation of the two modalities, accurately registered anatomical and functional images can be obtained. Since the introduction of the first PET/CT prototype more than 6 years ago, numerous patients with cancer have been scanned on commercial PET/CT devices worldwide. The commercial designs feature multidetector spiral CT and high-performance PET components. Experience has demonstrated an increased level of accuracy and confidence in the

  14. Gamma camera based Positron Emission Tomography: a study of the viability on quantification; Tomografia por emissao de positrons com sistemas PET/SPECT: um estudo da viabilidade de quantifizacao

    Energy Technology Data Exchange (ETDEWEB)

    Pozzo, Lorena

    2005-07-01

    Positron Emission Tomography (PET) is a Nuclear Medicine imaging modality for diagnostic purposes. Pharmaceuticals labeled with positron emitters are used and images which represent the in vivo biochemical process within tissues can be obtained. The positron/electron annihilation photons are detected in coincidence and this information is used for object reconstruction. Presently, there are two types of systems available for this imaging modality: the dedicated systems and those based on gamma camera technology. In this work, we utilized PET/SPECT systems, which also allows for the traditional Nuclear Medicine studies based on single photon emitters. There are inherent difficulties which affect quantification of activity and other indices. They are related to the Poisson nature of radioactivity, to radiation interactions with patient body and detector, noise due to statistical nature of these interactions and to all the detection processes, as well as the patient acquisition protocols. Corrections are described in the literature and not all of them are implemented by the manufacturers: scatter, attenuation, random, decay, dead time, spatial resolution, and others related to the properties of each equipment. The goal of this work was to assess these methods adopted by two manufacturers, as well as the influence of some technical characteristics of PET/SPECT systems on the estimation of SUV. Data from a set of phantoms were collected in 3D mode by one camera and 2D, by the other. We concluded that quantification is viable in PET/SPECT systems, including the estimation of SUVs. This is only possible if, apart from the above mentioned corrections, the camera is well tuned and coefficients for sensitivity normalization and partial volume corrections are applied. We also verified that the shapes of the sources used for obtaining these factors play a role on the final results and should be delt with carefully in clinical quantification. Finally, the choice of the region

  15. 77 FR 8262 - Draft Guidance on Investigational New Drug Applications for Positron Emission Tomography Drugs...

    Science.gov (United States)

    2012-02-14

    ... Positron Emission Tomography Drugs; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice... entitled ``Investigational New Drug Applications for Positron Emission Tomography (PET) Drugs.'' The draft... Applications for Positron Emission Tomography (PET) drugs.'' The draft guidance summarizes the IND process...

  16. Pulmonary studies using positron emission tomography

    International Nuclear Information System (INIS)

    The detailed investigation of regional differences in lung function at a local level began when suitable γ-ray emitting isotopes and focused external radiation detectors (especially the Anger γ-camera) became available. A major recent advance has been the development of positron emission tomography (PET), which provides a powerful combination of highly accurate tomographic reconstruction of radioisotope concentration with a potentially unlimited list of biological compounds to be labelled with the positron emitting isotopes of oxygen, carbon and fluorine. Early studies using PET focused on the inhalation of 11CO (or C15O) and 19Ne gases and the intravenous injection of 13N in saline and H215O for the measurement of relatively simple aspects of regional lung function, such as tissue, blood and gas volumes, blood flow, ventilation and ventilation/perfusion (V'A/Q'). More recent work has been directed towards the more challenging areas of regional endothelial permeability, carbohydrate utilization, enzyme and receptor binding assays, and in vivo pharmacokinetics. The short physical half-lives of the isotopes (17 s to 2 h) and the noninvasive nature of PET allows serial measurements to be made on patients (within the constraints of permitted radiation doses) to assess the effect of physiological and therapeutic interventions. (au) 80 refs

  17. Simulation of the annihilation emission of galactic positrons; Modelisation de l'emission d'annihilation des positrons Galactiques

    Energy Technology Data Exchange (ETDEWEB)

    Gillard, W

    2008-01-15

    Positrons annihilate in the central region of our Galaxy. This has been known since the detection of a strong emission line centered on an energy of 511 keV in the direction of the Galactic center. This gamma-ray line is emitted during the annihilation of positrons with electrons from the interstellar medium. The spectrometer SPI, onboard the INTEGRAL observatory, performed spatial and spectral analyses of the positron annihilation emission. This thesis presents a study of the Galactic positron annihilation emission based on models of the different interactions undergone by positrons in the interstellar medium. The models are relied on our present knowledge of the properties of the interstellar medium in the Galactic bulge, where most of the positrons annihilate, and of the physics of positrons (production, propagation and annihilation processes). In order to obtain constraints on the positrons sources and physical characteristics of the annihilation medium, we compared the results of the models to measurements provided by the SPI spectrometer. (author)

  18. Positron emission tomography in urological cancer

    International Nuclear Information System (INIS)

    In staging cancer of the urinary bladder, the kidneys and the prostate and of testicular cancer there is a need for detecting tumor involvement of the lymph nodes to avoid surgical exploration. Positron emission tomography (PET) using fluorodeoxyglucose (FDG) can detect tumorous lymph nodes (sensitivity: 70%, specificity: 85%) which is helpful for several patients. In carcinoma of the prostate, other radiotracers than FDG (e.g. C-11-choline) might be more sensitive to detect tumorous lymph nodes. Up to now no diagnostical benefit of PET in germ cell tumors could be demonstrated in the published small series. In principle FDG-PET is useful in diagnosis of recurrence. In germ cell cancer FDG-PET seems to identify effectively persistent vital tumor tissue after chemotherapy. A multicenter study was initiated to demonstrate the potential of FDG-PET in a sufficient number of patients with germ cell tumor. (orig.)

  19. Compact conscious animal positron emission tomography scanner

    Science.gov (United States)

    Schyler, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois; Volkow, Nora

    2006-10-24

    A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal for an event, generating an address signal representing a detecting channel, generating a detector channel signal including the time and address signals, and generating a composite signal including the channel signal and similarly generated signals. The composite signal includes events from detectors in a block and is serially output. An apparatus that serially transfers annihilation information from a block includes time signal generators for detectors in a block and an address and channel signal generator. The PET scanner includes a ring tomograph that mounts onto a portion of an animal, which includes opposing block pairs. Each of the blocks in a block pair includes a scintillator layer, detection array, front-end array, and a serial encoder. The serial encoder includes time signal generators and an address signal and channel signal generator.

  20. Positron emission tomography of the heart

    International Nuclear Information System (INIS)

    Positron emission computed tomography (PCT) represents an important new tool for the noninvasive evaluation and, more importantly, quantification of myocardial performance. Most currently available techniques permit assessment of only one aspect of cardiac function, i.e., myocardial perfusion by gamma scintillation camera imaging with Thallium-201 or left ventricular function by echocardiography or radionuclide angiocardiography. With PCT it may become possible to study all three major segments of myocardial performance, i.e., regional blood flow, mechanical function and, most importantly, myocardial metabolism. Each of these segments can either be evaluated separately or in combination. This report briefly describes the principles and technological advantages of the imaging device, reviews currently available radioactive tracers and how they can be employed for the assessment of flow, function and metabolism; and, lastly, discusses possible applications of PCT for the study of cardiac physiology or its potential role in the diagnosis of cardiac disease

  1. Positron emission tomography and basal ganglia functions

    International Nuclear Information System (INIS)

    With the advent of positron emission tomography (PET), studies on the human brain function and pathophysiology of brain damage have been extremely progressed. It is well-known that the basal ganglia plays an important role as one of the central nervous system involved in exercise regulation. More recently, the potential involvement of the basal ganglia in psychological processes, such as cognitive function, has been pointed out, receiving much attention. In spite of such a lot of studies, however, basal ganglia function remains unclear. This paper describes the relationships between PET findings and basal ganglia function. PET findings are discussed in relation to brain energy metabolism and striatal dopamine function. Pathophysiology of the basal ganglia are described in terms of the following diseases: Parkinson's disease, Parkinson's syndrome, progressive supranuclear palsy, Huntington's disease, and dystonia. Physiological backgrounds of the basal ganglia for PET images are also referred to. (N.K.) 75 refs

  2. Positron emission tomography of the heart

    Energy Technology Data Exchange (ETDEWEB)

    Schelbert, H.R.; Phelps, M.E.; Kuhl, D.E.

    1979-01-01

    Positron emission computed tomography (PCT) represents an important new tool for the noninvasive evaluation and, more importantly, quantification of myocardial performance. Most currently available techniques permit assessment of only one aspect of cardiac function, i.e., myocardial perfusion by gamma scintillation camera imaging with Thallium-201 or left ventricular function by echocardiography or radionuclide angiocardiography. With PCT it may become possible to study all three major segments of myocardial performance, i.e., regional blood flow, mechanical function and, most importantly, myocardial metabolism. Each of these segments can either be evaluated separately or in combination. This report briefly describes the principles and technological advantages of the imaging device, reviews currently available radioactive tracers and how they can be employed for the assessment of flow, function and metabolism; and, lastly, discusses possible applications of PCT for the study of cardiac physiology or its potential role in the diagnosis of cardiac disease.

  3. Methods and applications of positron-based medical imaging

    Science.gov (United States)

    Herzog, H.

    2007-02-01

    Positron emission tomography (PET) is a diagnostic imaging method to examine metabolic functions and their disorders. Dedicated ring systems of scintillation detectors measure the 511 keV γ-radiation produced in the course of the positron emission from radiolabelled metabolically active molecules. A great number of radiopharmaceuticals labelled with 11C, 13N, 15O, or 18F positron emitters have been applied both for research and clinical purposes in neurology, cardiology and oncology. The recent success of PET with rapidly increasing installations is mainly based on the use of [ 18F]fluorodeoxyglucose (FDG) in oncology where it is most useful to localize primary tumours and their metastases.

  4. Liquid Xenon Detectors for Positron Emission Tomography

    International Nuclear Information System (INIS)

    PET is a functional imaging technique based on detection of annihilation photons following beta decay producing positrons. In this paper, we present the concept of a new PET system for preclinical applications consisting of a ring of twelve time projection chambers filled with liquid xenon viewed by avalanche photodiodes. Simultaneous measurement of ionization charge and scintillation light leads to a significant improvement to spatial resolution, image quality, and sensitivity. Simulated performance shows that an energy resolution of < 10% (FWHM) and a sensitivity of 15% are achievable. First tests with a prototype TPC indicate position resolution < 1 mm (FWHM).

  5. Liquid Xenon Detectors for Positron Emission Tomography

    CERN Document Server

    Miceli, A; Benard, F; Bryman, D A; Kurchaninov, L; Martin, J P; Muennich, A; Retiere, F; Ruth, T J; Sossi, V; Stoessl, A J

    2011-01-01

    PET is a functional imaging technique based on detection of annihilation photons following beta decay producing positrons. In this paper, we present the concept of a new PET system for preclinical applications consisting of a ring of twelve time projection chambers filled with liquid xenon viewed by avalanche photodiodes. Simultaneous measurement of ionization charge and scintillation light leads to a significant improvement to spatial resolution, image quality, and sensitivity. Simulated performance shows that an energy resolution of <10% (FWHM) and a sensitivity of 15% are achievable. First tests with a prototype TPC indicate position resolution <1 mm (FWHM).

  6. Individualized Positron Emission Tomography–Based Isotoxic Accelerated Radiation Therapy Is Cost-Effective Compared With Conventional Radiation Therapy: A Model-Based Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Bongers, Mathilda L., E-mail: ml.bongers@vumc.nl [Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam (Netherlands); Coupé, Veerle M.H. [Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam (Netherlands); De Ruysscher, Dirk [Radiation Oncology University Hospitals Leuven/KU Leuven, Leuven (Belgium); Department of Radiation Oncology, GROW Research Institute, Maastricht University Medical Center, Maastricht (Netherlands); Oberije, Cary; Lambin, Philippe [Department of Radiation Oncology, GROW Research Institute, Maastricht University Medical Center, Maastricht (Netherlands); Uyl-de Groot, Cornelia A. [Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam (Netherlands); Institute for Medical Technology Assessment, Erasmus University Rotterdam, Rotterdam (Netherlands)

    2015-03-15

    Purpose: To evaluate long-term health effects, costs, and cost-effectiveness of positron emission tomography (PET)-based isotoxic accelerated radiation therapy treatment (PET-ART) compared with conventional fixed-dose CT-based radiation therapy treatment (CRT) in non-small cell lung cancer (NSCLC). Methods and Materials: Our analysis uses a validated decision model, based on data of 200 NSCLC patients with inoperable stage I-IIIB. Clinical outcomes, resource use, costs, and utilities were obtained from the Maastro Clinic and the literature. Primary model outcomes were the difference in life-years (LYs), quality-adjusted life-years (QALYs), costs, and the incremental cost-effectiveness and cost/utility ratio (ICER and ICUR) of PET-ART versus CRT. Model outcomes were obtained from averaging the predictions for 50,000 simulated patients. A probabilistic sensitivity analysis and scenario analyses were carried out. Results: The average incremental costs per patient of PET-ART were €569 (95% confidence interval [CI] €−5327-€6936) for 0.42 incremental LYs (95% CI 0.19-0.61) and 0.33 QALYs gained (95% CI 0.13-0.49). The base-case scenario resulted in an ICER of €1360 per LY gained and an ICUR of €1744 per QALY gained. The probabilistic analysis gave a 36% probability that PET-ART improves health outcomes at reduced costs and a 64% probability that PET-ART is more effective at slightly higher costs. Conclusion: On the basis of the available data, individualized PET-ART for NSCLC seems to be cost-effective compared with CRT.

  7. Individualized Positron Emission Tomography–Based Isotoxic Accelerated Radiation Therapy Is Cost-Effective Compared With Conventional Radiation Therapy: A Model-Based Evaluation

    International Nuclear Information System (INIS)

    Purpose: To evaluate long-term health effects, costs, and cost-effectiveness of positron emission tomography (PET)-based isotoxic accelerated radiation therapy treatment (PET-ART) compared with conventional fixed-dose CT-based radiation therapy treatment (CRT) in non-small cell lung cancer (NSCLC). Methods and Materials: Our analysis uses a validated decision model, based on data of 200 NSCLC patients with inoperable stage I-IIIB. Clinical outcomes, resource use, costs, and utilities were obtained from the Maastro Clinic and the literature. Primary model outcomes were the difference in life-years (LYs), quality-adjusted life-years (QALYs), costs, and the incremental cost-effectiveness and cost/utility ratio (ICER and ICUR) of PET-ART versus CRT. Model outcomes were obtained from averaging the predictions for 50,000 simulated patients. A probabilistic sensitivity analysis and scenario analyses were carried out. Results: The average incremental costs per patient of PET-ART were €569 (95% confidence interval [CI] €−5327-€6936) for 0.42 incremental LYs (95% CI 0.19-0.61) and 0.33 QALYs gained (95% CI 0.13-0.49). The base-case scenario resulted in an ICER of €1360 per LY gained and an ICUR of €1744 per QALY gained. The probabilistic analysis gave a 36% probability that PET-ART improves health outcomes at reduced costs and a 64% probability that PET-ART is more effective at slightly higher costs. Conclusion: On the basis of the available data, individualized PET-ART for NSCLC seems to be cost-effective compared with CRT

  8. Design, Synthesis, and Evaluation of an (18)F-Labeled Radiotracer Based on Celecoxib-NBD for Positron Emission Tomography (PET) Imaging of Cyclooxygenase-2 (COX-2).

    Science.gov (United States)

    Kaur, Jatinder; Tietz, Ole; Bhardwaj, Atul; Marshall, Alison; Way, Jenilee; Wuest, Melinda; Wuest, Frank

    2015-10-01

    A series of novel fluorine-containing cyclooxygenase-2 (COX-2) inhibitors was designed and synthesized based on the previously reported fluorescent COX-2 imaging agent celecoxib-NBD (3; NBD=7-nitrobenzofurazan). In vitro COX-1/COX-2 inhibitory data show that N-(4-fluorobenzyl)-4-(5-p-tolyl-3-trifluoromethylpyrazol-1-yl)benzenesulfonamide (5; IC50 =0.36 μM, SI>277) and N-fluoromethyl-4-(5-p-tolyl-3-trifluoromethylpyrazol-1-yl)benzenesulfonamide (6; IC50 =0.24 μM, SI>416) are potent and selective COX-2 inhibitors. Compound 5 was selected for radiolabeling with the short-lived positron emitter fluorine-18 ((18) F) and evaluated as a positron emission tomography (PET) imaging agent. Radiotracer [(18) F]5 was analyzed in vitro and in vivo using human colorectal cancer model HCA-7. Although radiotracer uptake into COX-2-expressing HCA-7 cells was high, no evidence for COX-2-specific binding was found. Radiotracer uptake into HCA-7 tumors in vivo was low and similar to that of muscle, used as reference tissue. PMID:26287271

  9. Perspectives for positron emission tomography with RPCs

    International Nuclear Information System (INIS)

    Full text: The basis of PET (Positron Emission Tomography) consists on the administration of a radioactive isotope attached to a tracer that permits to reveal its molecular pathways in a human body. A 3-D Complete-Body-Scan is desired in order to minimize the radiation dose to the patient and to increase the sensitivity of the axial field of view (FOV). A major candidate for gamma pair detection in 3-D Complete- Body-Scan are the RPCs (Resistive Plate Counters). They consist in a longitudinal microstrip grid 1.5 mm thick, spaced at 1 mm. The grid is placed between a large electric resistive glass anode and an aluminum cathode. The gap, around 300 m, is filled with a special gas and is polarized at around 6 kV. Every microstrip is equipped with high-speed preamplifier at both ends, allowing time of flight measurements. The RPC are solely tracking devices enjoying a large density of detection units. By construction they are able to provide an extremely large transverse resolution, the collecting leads being some 2.5 mm spaced. The longitudinal resolution is less sensitive, depending on the speed of the time of flight electronics. At this moment we estimate a 20 mm resolution. The RPCs present two main features: large longitudinal dimension and large transversal resolution which made them ideal for complete-body-scan devices. These peculiar features are the keys of a RPCs tomographic device. The evaluation of RPCs for 3-D Complete-Body-Scan followed two steps, the simulation of data acquisition and the image reconstruction. We choose the detecting base unit like a RPC, 2 meters long and 0.5 meters wide. According to previous assumptions this plate has a transverse resolution of 256 detection units and a longitudinal resolution of 100. (The transversal step is around 2 mm and the longitudinal step about 20 mm). Several base units are assembled to form different detecting structures. Two plates form an open detection structure like a sandwich. Four and six plates are

  10. Recent developments in positron emission tomography (PET) instrumentation

    International Nuclear Information System (INIS)

    This paper presents recent detector developments and perspectives for positron emission tomography (PET) instrumentation used for medical research, as well as the physical processes in positron annihilation, photon scattering and detection, tomograph design considerations, and the potentials for new advances in detectors. 117 refs., 4 figs., 4 tabs

  11. Simultaneous emission and transmission scanning in positron emission tomography

    International Nuclear Information System (INIS)

    Examination by PET (positron emission tomography) scanning, following the dosage of 2-deoxy-18F fluoro-D-glucose (FDG), is positively utilized for the diagnosis of cancers, rather than for the purpose of studies. This is because the examination by FDG-PET (PET scanning following the dosage of FDG) ensures higher efficiency in discrimination of cancers, than conventional CT and PET. The method of whole body scanning by PET scanning following the dosage of FDG is effectively utilized not only for discrimination cancers, but also for determining the degree of malignancy of tumors and evaluating the methods of treatment of cancers. In conventional methods for examining the degree of malignancy of tumors and evaluating the methods of cancer treatment, it is necessary to correct for the gamma-ray attenuation, which requires a longer time for examination, increasing the physical and psychological pains of the patients. We have installed the simultaneous emission and transmission scanning capability into the HEADTOME-V of the Shimadzu SET-2000W Series positron emission tomographic scanning instruments, to establish an instrument that permits FDG-PET whole body scanning in actual clinical fields, with minimized physical and psychological pains of patients concerned, yet ensuring an outstandingly high examination efficiency. This report also presents some data obtained by this newly developed instrument and those obtained in practical applications. (author)

  12. A Comparison of Amplitude-Based and Phase-Based Positron Emission Tomography Gating Algorithms for Segmentation of Internal Target Volumes of Tumors Subject to Respiratory Motion

    International Nuclear Information System (INIS)

    Purpose: To quantitatively compare the accuracy of tumor volume segmentation in amplitude-based and phase-based respiratory gating algorithms in respiratory-correlated positron emission tomography (PET). Methods and Materials: List-mode fluorodeoxyglucose-PET data was acquired for 10 patients with a total of 12 fluorodeoxyglucose-avid tumors and 9 lymph nodes. Additionally, a phantom experiment was performed in which 4 plastic butyrate spheres with inner diameters ranging from 1 to 4 cm were imaged as they underwent 1-dimensional motion based on 2 measured patient breathing trajectories. PET list-mode data were gated into 8 bins using 2 amplitude-based (equal amplitude bins [A1] and equal counts per bin [A2]) and 2 temporal phase-based gating algorithms. Gated images were segmented using a commercially available gradient-based technique and a fixed 40% threshold of maximum uptake. Internal target volumes (ITVs) were generated by taking the union of all 8 contours per gated image. Segmented phantom ITVs were compared with their respective ground-truth ITVs, defined as the volume subtended by the tumor model positions covering 99% of breathing amplitude. Superior-inferior distances between sphere centroids in the end-inhale and end-exhale phases were also calculated. Results: Tumor ITVs from amplitude-based methods were significantly larger than those from temporal-based techniques (P=.002). For lymph nodes, A2 resulted in ITVs that were significantly larger than either of the temporal-based techniques (P<.0323). A1 produced the largest and most accurate ITVs for spheres with diameters of ≥2 cm (P=.002). No significant difference was shown between algorithms in the 1-cm sphere data set. For phantom spheres, amplitude-based methods recovered an average of 9.5% more motion displacement than temporal-based methods under regular breathing conditions and an average of 45.7% more in the presence of baseline drift (P<.001). Conclusions: Target volumes in images generated

  13. Amorphous silicon detectors in positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Conti, M. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy) Lawrence Berkeley Lab., CA (USA)); Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))

    1989-12-01

    The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters {epsilon}{sup 2}{tau}'s are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs.

  14. Utility of positron emission tomography in schwannomatosis.

    Science.gov (United States)

    Lieber, Bryan; Han, ByoungJun; Allen, Jeffrey; Fatterpekar, Girish; Agarwal, Nitin; Kazemi, Noojan; Zagzag, David

    2016-08-01

    Schwannomatosis is characterized by multiple non-intradermal schwannomas with patients often presenting with a painful mass in their extremities. In this syndrome malignant transformation of schwannomas is rare in spite of their large size at presentation. Non-invasive measures of assessing the biological behavior of plexiform neurofibromas in neurofibromatosis type 1 such as positron emission tomography (PET), CT scanning and MRI are well characterized but little information has been published on the use of PET imaging in schwannomatosis. We report a unique clinical presentation portraying the use of PET imaging in schwannomatosis. A 27-year-old woman presented with multiple, rapidly growing, large and painful schwannomas confirmed to be related to a constitutional mutation in the SMARCB1 complex. Whole body PET/MRI revealed numerous PET-avid tumors suggestive of malignant peripheral nerve sheath tumors. Surgery was performed on multiple tumors and none of them had histologic evidence of malignant transformation. Overall, PET imaging may not be a reliable predictor of malignant transformation in schwannomatosis, tempering enthusiasm for surgical interventions for tumors not producing significant clinical signs or symptoms. PMID:26960263

  15. Amorphous silicon detectors in positron emission tomography

    International Nuclear Information System (INIS)

    The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters ε2τ's are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs

  16. Myocardial energy metabolism by positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) permits quantitative measurement of myocardial blood flow and metabolism in vivo in the cardiovascular areas. F-18 fluorodeoxyglucose (FDG) and C-11 palmitate have been used for energy metabolism in the cardiac PET. In fasting condition, beta-oxydation of fatty acids is the major energy source in the normal myocardium, whereas glucose metabolism is enhanced in the ischemic myocardium. No metabolic substrate is used in the necrotic myocardium. Thus, quantitative measurement of substrate utilization enables differentiation of ischemic from normal or infarcted myocardium and precise assessment of tissue abnormalities in vivo. FDG is administrated in fasting condition in our institute in order to delineate ischemic myocardium as a hot spot with suppression of the FDG uptake in the normal myocardium. However, when compared to the postprandial condition, FDG uptake may be enhanced even in the infarcted tissue, and thus, may possibly overestimate the tissue viability. A certain quantification of FDG uptake may be warranted for an accurate evaluation of FDG uptake. We have been measured FDG uptake index as a fraction of injected dose (% dose/100g tissue). This index correlated well with myocardial metabolic rate of glucose by Phelps method in the fasting condition. Dynamic PET study after C-11 palmitate injection has been used for estimate of fatty acid utilization. The first component of the washout from the myocardium is considered as rate of beta-oxydation. However, the washout of this tracer seems to be strikingly different between the fasting and postprandial conditions. (J.P.N.)

  17. Patient radiation protection in positron emission tomography

    International Nuclear Information System (INIS)

    Patient radiation protection in Positron Emission Tomography (PET) is closely related to the correct execution of studies: proper scanner performance, and optimization of both image quality and patient dose. We describe the quality control tests considered as essential: scanner stability, spatial resolution, sensitivity and tomographic uniformity. Knowledge of the dose received by the critical organ and the effective dose for each radiopharmaceutical allows the establishment of strategies for dose optimization. Although a great variety of PET tracers exist, we review the dose produced by F-FDG, the most widely used tracer, and those used in our PET Center O-Water, N-Ammonia, C-Methionine, C-Choline, F-Choline, F-Dopa, and F-FHBG. Reduction of administered activity to the patient is the direct way to reduce the dose. Thus, PET acquisition in the 3D mode, with higher sensitivity, is a determining factor. In order to reduce the dose to different organs, efforts should be directed to the critical organs, mainly the urinary bladder wall. Finally, correct patient preparation improves, PET image quality, due to an optimum tracer uptake, which optimizes the dose to different organs. (Author) 25 refs

  18. Development of radioisotopically labeled compounds for clinical positron emission tomography

    International Nuclear Information System (INIS)

    It is its quantitative imaging capacity with high spatial resolution that makes positron emission tomography a unique tool for the development of quantitative tracer kinetic studies for the measurement of physiological processes in man. Research success in this area will depend on the ingenuity of biomedical scientists in prioritizing the development of tracers. Choices must be made based on the importance of different physiological measurements, the capacity to synthesize an appropriate radioisotopically labeled compound for this measurement and the ability to determine an adequate kinetic model for its interpretation. Examples are given of these steps in the development of PET tracers at the NIMH. 17 refs.; 1 table

  19. Positron emission tomography. Present status and Romanian perspectives

    International Nuclear Information System (INIS)

    Basic principles of the positron emission tomography (PET) are summarised. The main PET methods using short-lived radioisotopes (i.e.11 C, 13 N, 15 O, 18 F) are briefly reviewed. Three types of particle accelerators for radioisotopes production and medical uses (including radiotherapy), corresponding to the proton energy (Ep p p < 200 MeV) are presented. PET imaging equipment and procedures are discussed. Main radiopharmaceuticals based on beta decay for PET studies and their role in medicine is also described. Finally, perspectives for a PET program in Romania (Cyclotron + Radiochemistry + Tomograph ) are discussed. (author)

  20. Positron Emission Mammography with Multiple Angle Acquisition

    International Nuclear Information System (INIS)

    Positron emission mammography (PEM) of F-18 fluorodeoxyglucose (FDG) uptake in breast tumors with dedicated detectors typically has been accomplished with two planar detectors in a fixed position with the breast under compression. The potential use of PEM imaging at two detector positions to guide stereotactic breast biopsy has motivated us to use PEM coincidence data acquired at two or more detector positions together in a single image reconstruction. Multiple angle PEM acquisition and iterative image reconstruction were investigated using point source and compressed breast phantom acquisitions with 5, 9, 12 and 15 mm diameter spheres and a simulated tumor:background activity concentration ratio of 6:1. Image reconstruction was performed with an iterative MLEM algorithm that used coincidence events between any two detector pixels on opposed detector heads at each detector position. This present study compared two acquisition protocols: 2 angle acquisition with detector angular positions of -15 and +15 degrees and 11 angle acquisition with detector positions spaced at 3 degree increments over the range -15 to +15 degrees. Three- dimensional image resolution was assessed for the point source acquisitions, and contrast and signal-to-noise metrics were evaluated for the compressed breast phantom with different simulated tumor sizes. Radial and tangential resolutions were similar for the two protocols, while normal resolution was better for the 2 angle acquisition. Analysis is complicated by the asymmetric point spread functions. Signal- to-noise vs. contrast tradeoffs were better for 11 angle acquisition for the smallest visible 9 mm sphere, while tradeoff results were mixed for the larger and more easily visible 12 mm and 15 mm diameter spheres. Additional study is needed to better understand the performance of limited angle tomography for PEM. PEM tomography experiments with complete angular sampling are planned

  1. Positron emission tomography: physics, instrumentation, and image analysis.

    Science.gov (United States)

    Porenta, G

    1994-01-01

    Positron emission tomography (PET) is a noninvasive diagnostic technique that permits reconstruction of cross-sectional images of the human body which depict the biodistribution of PET tracer substances. A large variety of physiological PET tracers, mostly based on isotopes of carbon, nitrogen, oxygen, and fluorine is available and allows the in vivo investigation of organ perfusion, metabolic pathways and biomolecular processes in normal and diseased states. PET cameras utilize the physical characteristics of positron decay to derive quantitative measurements of tracer concentrations, a capability that has so far been elusive for conventional SPECT (single photon emission computed tomography) imaging techniques. Due to the short half lives of most PET isotopes, an on-site cyclotron and a radiochemistry unit are necessary to provide an adequate supply of PET tracers. While operating a PET center in the past was a complex procedure restricted to few academic centers with ample resources, PET technology has rapidly advanced in recent years and has entered the commercial nuclear medicine market. To date, the availability of compact cyclotrons with remote computer control, automated synthesis units for PET radiochemistry, high-performance PET cameras, and user-friendly analysis workstations permits installation of a clinical PET center within most nuclear medicine facilities. This review provides simple descriptions of important aspects concerning physics, instrumentation, and image analysis in PET imaging which should be understood by medical personnel involved in the clinical operation of a PET imaging center. PMID:7941595

  2. Positron emission tomography: Physics, instrumentation, and image analysis

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a noninvasive diagnostic technique that permits reconstruction of cross-sectional images of the human body which depict the biodistribution of PET tracer substances. A large variety of physiological PET tracers, mostly based on isotopes of carbon, nitrogen, oxygen, and fluorine is available and allows the in vivo investigation of organ perfusion, metabolic pathways and biomolecular processes in normal and diseased states. PET cameras utilize the physical characteristics of positron decay to derive quantitative measurements of tracer concentrations, a capability that has so far been elusive for conventional SPECT (single photon emission computed tomography) imaging techniques. Due to the short half lives of most PET isotopes, an on-site cyclotron and a radiochemistry unit are necessary to provide an adequate supply of PET tracers. While operating a PET center in the past was a complex procedure restricted to few academic centers with ample resources. PET technology has rapidly advanced in recent years and has entered the commercial nuclear medicine market. To date, the availability of compact cyclotrons with remote computer control, automated synthesis units for PET radiochemistry, high-performance PET cameras, and userfriendly analysis workstations permits installation of a clinical PET center within most nuclear medicine facilities. This review provides simple descriptions of important aspects concerning physics, instrumentation, and image analysis in PET imaging which should be understood by medical personnel involved in the clinical operation of a PET imaging center. (author)

  3. Time-Based Readout of a Silicon Photomultiplier (SiPM) for Time of Flight Positron Emission Tomography (TOF-PET)

    CERN Document Server

    Powolny, F; Brunner, S E; Hillemanns, H; Meyer, T; Garutti, E; Williams, M C S; Auffray, E; Shen, W; Goettlich, M; Jarron, P; Schultz-Coulon, H C

    2011-01-01

    Time of flight (TOF) measurements in positron emission tomography (PET) are very challenging in terms of timing performance, and should ideally achieve less than 100 ps FWHM precision. We present a time-based differential technique to read out silicon photomultipliers (SiPMs) which has less than 20 ps FWHM electronic jitter. The novel readout is a fast front end circuit (NINO) based on a first stage differential current mode amplifier with 20 Omega input resistance. Therefore the amplifier inputs are connected differentially to the SiPM's anode and cathode ports. The leading edge of the output signal provides the time information, while the trailing edge provides the energy information. Based on a Monte Carlo photon-generation model, HSPICE simulations were run with a 3 x 3 mm(2) SiPM-model, read out with a differential current amplifier. The results of these simulations are presented here and compared with experimental data obtained with a 3 x 3 x 15 mm(3) LSO crystal coupled to a SiPM. The measured time coi...

  4. Human cerebral circulation. Positron emission tomography studies

    International Nuclear Information System (INIS)

    We reviewed the literature on human cerebral circulation and oxygen metabolism, as measured by positron emission tomography (PET), with respect to normal values and of regulation of cerebral circulation. A multicenter study in Japan showed that between-center variations in cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) values were not considerably larger than the corresponding within-center variations. Overall mean±SD values in cerebral cortical regions of normal human subjects were as follows: CBF=44.4±6.5 ml/100 ml/min; CBV=3.8±0.7 ml/100 ml; OEF=0.44±0.06; CMRO2=3.3±0.5 ml/100 ml/min (11 PET centers, 70 subjects). Intrinsic regulation of cerebral circulation involves several factors. Autoregulation maintains CBF in response to changes in cerebral perfusion pressure; chemical factors such as PaCO2 affect cerebral vascular tone and alter CBF; changes in neural activity cause changes in cerebral energy metabolism and CBF; neurogenic control of CBF occurs by sympathetic innervation. Regional differences in vascular response to changes in PaCO2 have been reported, indicating regional differences in cerebral vascular tone. Relations between CBF and CBV during changes in PaCO2 and during changes in neural activity were in good agreement with Poiseuille's law. The mechanisms of vascular response to neural activation and deactivation were independent on those of responses to PaCO2 changes. CBV in a brain region is the sum of three components: arterial, capillary and venous blood volumes. It has been reported that the arterial blood volume fraction is approximately 30% in humans and that changes in human CBV during changes in PaCO2 are caused by changes in arterial blood volume without changes in venous blood volume. These findings should be considered in future studies of the pathophysiology of cerebrovascular diseases. (author) 136 refs

  5. Application of positron emission tomography in neurophysiology

    International Nuclear Information System (INIS)

    PET measures the distribution of positron-emitting radiotracers in the organs of living subjects, by means of the angular correlation of the gamma-rays originating from positron annihilation. The UBC/TRIUMF Program focusses the technique on measurements of brain physiology, and radio-labelled tracers have been developed for measurements of regional cerebral glucose metabolism, regional cerebral blood flow, regional synthesis of dopamine neurotransmitter, and regional density and kinetics of dopamine receptor sites. Data have been obtained on normal physiology, and deranged physiology in Alzheimer's disease, Huntington's disease, Parkinson's disease, and astrocytoma brain tumors undergoing pion radiation treatment

  6. Investigation of language lateralization mechanism by Positron Emission Tomography

    International Nuclear Information System (INIS)

    As language lateralization in the brain left hemisphere is one of the most well known but less understood characteristics of the human brain, this research thesis reports the use of brain functional imaging to address some specific aspects of this lateralization. In a first part, the author reports the study of mechanisms of recovery from aphasia after a left hemisphere lesion within a population of aphasic right-handers. Based on a contrast between patients with a persistent aphasia despite usual language therapies, and patients with a significant recovery after a melodic and rhythmic therapy (TMR), a PET-based (positron emission tomography) activation study has been developed, based on the opposition between usual language stimuli and stimuli accentuated by TMR. In the second part, the author explored more systematically on sane patients the influence of some physical characteristics of auditory stimulation on the induced functional asymmetry

  7. Impact of point spread function correction in standardized uptake value quantitation for positron emission tomography images. A study based on phantom experiments and clinical images

    International Nuclear Information System (INIS)

    While point spread function (PSF)-based positron emission tomography (PET) reconstruction effectively improves the spatial resolution and image quality of PET, it may damage its quantitative properties by producing edge artifacts, or Gibbs artifacts, which appear to cause overestimation of regional radioactivity concentration. In this report, we investigated how edge artifacts produce negative effects on the quantitative properties of PET. Experiments with a National Electrical Manufacturers Association (NEMA) phantom, containing radioactive spheres of a variety of sizes and background filled with cold air or water, or radioactive solutions, showed that profiles modified by edge artifacts were reproducible regardless of background μ values, and the effects of edge artifacts increased with increasing sphere-to-background radioactivity concentration ratio (S/B ratio). Profiles were also affected by edge artifacts in complex fashion in response to variable combinations of sphere sizes and S/B ratios; and central single-peak overestimation up to 50% was occasionally noted in relatively small spheres with high S/B ratios. Effects of edge artifacts were obscured in spheres with low S/B ratios. In patient images with a variety of focal lesions, areas of higher radioactivity accumulation were generally more enhanced by edge artifacts, but the effects were variable depending on the size of and accumulation in the lesion. PET images generated using PSF-based reconstruction are therefore not appropriate for the evaluation of SUV. (author)

  8. Comparison of Five Segmentation Tools for 18F-Fluoro-Deoxy-Glucose-Positron Emission Tomography-Based Target Volume Definition in Head and Neck Cancer

    International Nuclear Information System (INIS)

    Purpose: Target-volume delineation for radiation treatment to the head and neck area traditionally is based on physical examination, computed tomography (CT), and magnetic resonance imaging. Additional molecular imaging with 18F-fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) may improve definition of the gross tumor volume (GTV). In this study, five methods for tumor delineation on FDG-PET are compared with CT-based delineation. Methods and Materials: Seventy-eight patients with Stages II-IV squamous cell carcinoma of the head and neck area underwent coregistered CT and FDG-PET. The primary tumor was delineated on CT, and five PET-based GTVs were obtained: visual interpretation, applying an isocontour of a standardized uptake value of 2.5, using a fixed threshold of 40% and 50% of the maximum signal intensity, and applying an adaptive threshold based on the signal-to-background ratio. Absolute GTV volumes were compared, and overlap analyses were performed. Results: The GTV method of applying an isocontour of a standardized uptake value of 2.5 failed to provide successful delineation in 45% of cases. For the other PET delineation methods, volume and shape of the GTV were influenced heavily by the choice of segmentation tool. On average, all threshold-based PET-GTVs were smaller than on CT. Nevertheless, PET frequently detected significant tumor extension outside the GTV delineated on CT (15-34% of PET volume). Conclusions: The choice of segmentation tool for target-volume definition of head and neck cancer based on FDG-PET images is not trivial because it influences both volume and shape of the resulting GTV. With adequate delineation, PET may add significantly to CT- and physical examination-based GTV definition

  9. Methodological review on functional neuroimaging using positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hae Jeong [Yonsei University, College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    Advance of neuroimaging technique has greatly influenced recent brain research field. Among various neuroimaging modalities, positron emission tomography has played a key role in molecular neuroimaging though functional MRI has taken over its role in the cognitive neuroscience. As the analysis technique for PET data is more sophisticated, the complexity of the method is more increasing. Despite the wide usage of the neuroimaging techniques, the assumption and limitation of procedures have not often been dealt with for the clinician and researchers, which might be critical for reliability and interpretation of the results. In the current paper, steps of voxel-based statistical analysis of PET including preprocessing, intensity normalization, spatial normalization, and partial volume correction will be revisited in terms of the principles and limitations. Additionally, new image analysis techniques such as surface-based PET analysis, correlational analysis and multimodal imaging by combining PET and DTI, PET and TMS or EEG will also be discussed.

  10. Timing performance comparison of digital methods in positron emission tomography

    International Nuclear Information System (INIS)

    Accurate timing information is essential in positron emission tomography (PET). Recent improvements in high speed electronics made digital methods more attractive to find alternative solutions to create a time mark for an event. Two new digital methods (mean PMT pulse model, MPPM, and median filtered zero crossing method, MFZCM) were introduced in this work and compared to traditional methods such as digital leading edge (LE) and digital constant fraction discrimination (CFD). In addition, the performances of all four digital methods were compared to analog based LE and CFD. The time resolution values for MPPM and MFZCM were measured below 300 ps at 1.6 GS/s and above that was similar to the analog based coincidence timing results. In addition, the two digital methods were insensitive to the changes in threshold setting that might give some improvement in system dead time.

  11. Methodological review on functional neuroimaging using positron emission tomography

    International Nuclear Information System (INIS)

    Advance of neuroimaging technique has greatly influenced recent brain research field. Among various neuroimaging modalities, positron emission tomography has played a key role in molecular neuroimaging though functional MRI has taken over its role in the cognitive neuroscience. As the analysis technique for PET data is more sophisticated, the complexity of the method is more increasing. Despite the wide usage of the neuroimaging techniques, the assumption and limitation of procedures have not often been dealt with for the clinician and researchers, which might be critical for reliability and interpretation of the results. In the current paper, steps of voxel-based statistical analysis of PET including preprocessing, intensity normalization, spatial normalization, and partial volume correction will be revisited in terms of the principles and limitations. Additionally, new image analysis techniques such as surface-based PET analysis, correlational analysis and multimodal imaging by combining PET and DTI, PET and TMS or EEG will also be discussed

  12. Positron emission tomography in colorectal cancer;Tomografia por emissao de positron no cancer colorretal

    Energy Technology Data Exchange (ETDEWEB)

    Gabure, Jose Luiz de Carvalho; Bacega, Marcelle Francine [Universidade Cidade de Sao Paulo (UNICID), Sao Paulo, SP (Brazil); Racy, Douglas Jorge; Lima, Rodrigo Vaz de; Rigo, Leticia, E-mail: letirigo3@hotmail.co [Med Imagem Diagnosticos por Imagem, Sao Paulo, SP (Brazil)

    2009-12-15

    After an introduction on the physical and biological basics of positron emission tomography, this paper reviews the current status of PET imaging using the glucose analogue FDG in colorectal cancer. The use of PET-FDG is reviewed for detection, initial staging, therapy monitoring and staging of disease relapse. (author)

  13. Physical and technical basis of positron emission tomography (PET)

    International Nuclear Information System (INIS)

    Positron emission tomography utilizes the annihilation of positrons, generating pairs of gamma quanta which are emitted in opposing directions. 'Electronic collimation' is performed by coincident detection of both quanta. Thus, there is no need for mechanical collimators and no limiting connection between sensitivity and spatial resolution. Transversal tomograms are reconstructed from the projection data by means of highly sophisticated data processing. The half life of the most positron emitters used in medical applications is short and of the order of some minutes. Therefore, many positron emitters have to be produced on-side by means of a cyclotron. PET is superior to SPECT with respect to physical and technical aspects, but the high costs of PET limit its wide-spread use up to now. (orig.)

  14. Improved sampling in positron emission tomography

    International Nuclear Information System (INIS)

    The biomedical research performed with the Donner 280-Crystal Positron Tomograph requires data acquisition times of five seconds or less and the ability to gate the data acquisition for periods during the cardiac cycle when the heart is nearly at rest. These requirements pose severe restrictions on the amount of detector movement and have motivated the search for a scheme that improves lateral sampling with a minimum number of detector positions. A new approach, developed by our group, involves only two positions of the detector assembly and increases lateral sampling uniformly by a factor of two. This new approach is referred as clamshell sampling. To test clamshell sampling we performed Monte Carlo computer simulations of data acquisition with the new geometry. Hot spots of varying sizes and separation comprise the model used in a geometry scaled to test imaging the human head with the Donner 280-Crystal Positron Tomograph

  15. Non-oncological positron emission tomography (PET): brain imaging

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) allows evaluation of the central nervous system function. Imaging of regional cerebral blood flow and metabolism, and of several neurotransmission systems may be obtained using PET. PET quantification is accurate and has good test-retest reliability. For research purposes, PET has been used to study brain physiology, to explore neurological and psychiatric diseases pathophysiology and for the new drugs research and development. F.D.G. is the only PET radioligand with clinical application. Following criteria of evidence-based medicine, the clinical indications of F.D.G.-PET are: evaluation of treated gliomas, pre surgical study of partial refractory epilepsy and diagnosis of Alzheimer's disease when it is impossible to differentiate clinically from fronto-temporal dementia

  16. Axial positrons emission tomography: from mouse to human brain imaging

    International Nuclear Information System (INIS)

    Positrons emission tomography is a nuclear imaging technics using nuclear decays. It is used both in clinical and preclinical studies. The later requires the use of small animals such as the mouse. The objective is to obtain the best signal with the best spatial resolution. Yet, a weight ratio between humans and mice indicates the need of a sub-millimeter resolution. A conventional scanner is based on detection modules surrounding the object to image and arranged perpendicularly. This implies a strong relationship between efficiency and spatial resolution. This work focuses on the axial geometry in which detection modules are arranged parallel to the object. This limits the relationship between the figures of merit, leading to both high spatial resolution and efficiency. The simulations of prototypes showed great perspectives in term of sub-millimeter resolution with efficiencies of 15 or 40% according to the scanner's axial extension. These results indicate great perspectives for both clinical and preclinical imaging. (author)

  17. Positron-emission tomography and cerebral metabolism

    International Nuclear Information System (INIS)

    In addition to the fact that radio-isotopes allow iso-atom labelling, they are short-lived and consequently may be injected into humans without serious problems of radiation damage. They disintegrate by emitting positrons which can be detected by external counting by virtue of the two 511 keV gamma rays emitted at the same time in opposite directions. These properties are used for tomographic detection and permit quantitative measurements of the radio-activity method will be described. The first concerns the transport of amino-acids into the brain, the second, the metabolism of psychoactive drugs. (orig./VJ)

  18. Positron Emission Tomography/Computed Tomography Imaging of Residual Skull Base Chordoma Before Radiotherapy Using Fluoromisonidazole and Fluorodeoxyglucose: Potential Consequences for Dose Painting

    Energy Technology Data Exchange (ETDEWEB)

    Mammar, Hamid, E-mail: hamid.mammar@unice.fr [Radiation Oncology Department, Antoine Lacassagne Center, Nice (France); CNRS-UMR 6543, Institute of Developmental Biology and Cancer, University of Nice Sophia Antipolis, Nice (France); Kerrou, Khaldoun; Nataf, Valerie [Department of Nuclear Medicine and Radiopharmacy, Tenon Hospital, and University Pierre et Marie Curie, Paris (France); Pontvert, Dominique [Proton Therapy Center of Orsay, Curie Institute, Paris (France); Clemenceau, Stephane [Department of Neurosurgery, Pitie-Salpetriere Hospital, Paris (France); Lot, Guillaume [Department of Neurosurgery, Adolph De Rothschild Foundation, Paris (France); George, Bernard [Department of Neurosurgery, Lariboisiere Hospital, Paris (France); Polivka, Marc [Department of Pathology, Lariboisiere Hospital, Paris (France); Mokhtari, Karima [Department of Pathology, Pitie-Salpetriere Hospital, Paris (France); Ferrand, Regis; Feuvret, Loiec; Habrand, Jean-louis [Proton Therapy Center of Orsay, Curie Institute, Paris (France); Pouyssegur, Jacques; Mazure, Nathalie [CNRS-UMR 6543, Institute of Developmental Biology and Cancer, University of Nice Sophia Antipolis, Nice (France); Talbot, Jean-Noeel [Department of Nuclear Medicine and Radiopharmacy, Tenon Hospital, and University Pierre et Marie Curie, Paris (France)

    2012-11-01

    Purpose: To detect the presence of hypoxic tissue, which is known to increase the radioresistant phenotype, by its uptake of fluoromisonidazole (18F) (FMISO) using hybrid positron emission tomography/computed tomography (PET/CT) imaging, and to compare it with the glucose-avid tumor tissue imaged with fluorodeoxyglucose (18F) (FDG), in residual postsurgical skull base chordoma scheduled for radiotherapy. Patients and Methods: Seven patients with incompletely resected skull base chordomas were planned for high-dose radiotherapy (dose {>=}70 Gy). All 7 patients underwent FDG and FMISO PET/CT. Images were analyzed qualitatively by visual examination and semiquantitatively by computing the ratio of the maximal standardized uptake value (SUVmax) of the tumor and cerebellum (T/C R), with delineation of lesions on conventional imaging. Results: Of the eight lesion sites imaged with FDG PET/CT, only one was visible, whereas seven of nine lesions were visible on FMISO PET/CT. The median SUVmax in the tumor area was 2.8 g/mL (minimum 2.1; maximum 3.5) for FDG and 0.83 g/mL (minimum 0.3; maximum 1.2) for FMISO. The T/C R values ranged between 0.30 and 0.63 for FDG (median, 0.41) and between 0.75 and 2.20 for FMISO (median,1.59). FMISO T/C R >1 in six lesions suggested the presence of hypoxic tissue. There was no correlation between FMISO and FDG uptake in individual chordomas (r = 0.18, p = 0.7). Conclusion: FMISO PET/CT enables imaging of the hypoxic component in residual chordomas. In the future, it could help to better define boosted volumes for irradiation and to overcome the radioresistance of these lesions. No relationship was founded between hypoxia and glucose metabolism in these tumors after initial surgery.

  19. MR imaging and positron emission tomography of cortical heterotopia

    International Nuclear Information System (INIS)

    Heterotopia of the gray matter is a developmental malformation in which ectopic cortex is found in the white matter of the brain. A case of a 33-year-old man with cortical heterotopia who had a lifelong history of seizures and psychomotor retardation is reported, including the results of cerebral CT, magnetic resonance imaging, and positron emission tomography using 18F-2-deoxyglucose

  20. Physiopathology of ischemic strokes: the input of positron emission tomography

    International Nuclear Information System (INIS)

    The tomography by positrons emissions has brought essential physiological and pathological knowledge relative to cerebral vascular accidents in the acute phase, because it is possible to measure the cerebral blood flow, the oxygen extraction rate and the local oxygen consumption. (N.C.)

  1. Advance of molecular imaging with positron emission tomography

    International Nuclear Information System (INIS)

    Molecular imaging with positron emission tomography (PET) is an important field of molecular imaging. This article summarizes the fundamental of PET molecular imaging technique and its application in protein function, gene expression and gene therapy, receptor imaging, and blood-flow infusion and metabolism imaging. (authors)

  2. Amyloid-β positron emission tomography imaging probes

    DEFF Research Database (Denmark)

    Kepe, Vladimir; Moghbel, Mateen C; Långström, Bengt;

    2013-01-01

    number of factors appear to preclude these probes from clinical utilization. As the available "amyloid specific" positron emission tomography imaging probes have failed to demonstrate diagnostic value and have shown limited utility for monitoring therapeutic interventions in humans, a debate on their...

  3. Skeletal muscle perfusion measured by positron emission tomography during exercise

    NARCIS (Netherlands)

    Ament, W; Lubbers, J; Rakhorst, G; Vaalburg, W; Verkerke, GJ; Paans, AMJ; Willemsen, ATM

    1998-01-01

    The applicability of (H2O)-O-15-positron emission tomographic (PET) imaging for the assessment of skeletal muscle perfusion during exercise was investigated in five healthy subjects performing intermittent isometric contractions on a calf ergometer. The workload of the left calf muscles was kept con

  4. Positron emission tomography/computerized tomography in lung cancer

    OpenAIRE

    Sahiner, Ilgin; Vural, Gulin Ucmak

    2014-01-01

    Positron emission tomography (PET) using 2-(18F)-flouro-2-deoxy-D-glucose (FDG) has emerged as a useful tool in the clinical work-up of lung cancer. This review article provides an overview of applications of PET in diagnosis, staging, treatment response evaluation, radiotherapy planning, recurrence assessment and prognostication of lung cancer.

  5. 3D fast reconstruction in positron emission tomography

    International Nuclear Information System (INIS)

    The issue of long reconstruction times in positron emission tomography (PET) has been addressed from several points of view, resulting in an affordable dedicated system capable of handling routine 3D reconstructions in a few minutes per frame : on the hardware side using fast processors and a parallel architecture, and on the software side, using efficient implementation of computationally less intensive algorithms

  6. Positron Emission Tomography Based Elucidation of the Enhanced Permeability and Retention Effect in Dogs with Cancer Using Copper-64 Liposomes.

    Science.gov (United States)

    Hansen, Anders E; Petersen, Anncatrine L; Henriksen, Jonas R; Boerresen, Betina; Rasmussen, Palle; Elema, Dennis R; Rosenschöld, Per Munck af; Kristensen, Annemarie T; Kjær, Andreas; Andresen, Thomas L

    2015-07-28

    Since the first report of the enhanced permeability and retention (EPR) effect, the research in nanocarrier based antitumor drugs has been intense. The field has been devoted to treatment of cancer by exploiting EPR-based accumulation of nanocarriers in solid tumors, which for many years was considered to be a ubiquitous phenomenon. However, the understanding of differences in the EPR-effect between tumor types, heterogeneities within each patient group, and dependency on tumor development stage in humans is sparse. It is therefore important to enhance our understanding of the EPR-effect in large animals and humans with spontaneously developed cancer. In the present paper, we describe a novel loading method of copper-64 into PEGylated liposomes and use these liposomes to evaluate the EPR-effect in 11 canine cancer patients with spontaneous solid tumors by PET/CT imaging. We thereby provide the first high-resolution analysis of EPR-based tumor accumulation in large animals. We find that the EPR-effect is strong in some tumor types but cannot be considered a general feature of solid malignant tumors since we observed a high degree of accumulation heterogeneity between tumors. Six of seven included carcinomas displayed high uptake levels of liposomes, whereas one of four sarcomas displayed signs of liposome retention. We conclude that nanocarrier-radiotracers could be important in identifying cancer patients that will benefit from nanocarrier-based therapeutics in clinical practice. PMID:26022907

  7. Value of positron emission tomography and computer tomography (PET/CT) for urologic malignancies

    International Nuclear Information System (INIS)

    Positron emission tomography is a functional imaging technique that allows the detection of the regional metabolic rate, and is often coupled with other morphological imaging technique such as computed tomography. The rationale for its use is based on the clearly demonstrated fact that functional changes in tumor processes happen before morphological changes. Its introduction to the clinical practice added a new dimension in conventional imaging techniques. This review presents the current and proposed indications of the use of positron emission/computed tomography for prostate, bladder and testes, and the potential role of this exam in radiotherapy planning. (authors)

  8. [Value of positron emission tomography and computer tomography (PET/CT) for urologic malignancies].

    Science.gov (United States)

    Boujelbene, N; Prior, J O; Boubaker, A; Azria, D; Schaffer, M; Gez, E; Jichlinski, P; Meuwly, J-Y; Mirimanoff, R O; Ozsahin, M; Zouhair, A

    2011-07-01

    Positron emission tomography is a functional imaging technique that allows the detection of the regional metabolic rate, and is often coupled with other morphological imaging technique such as computed tomography. The rationale for its use is based on the clearly demonstrated fact that functional changes in tumor processes happen before morphological changes. Its introduction to the clinical practice added a new dimension in conventional imaging techniques. This review presents the current and proposed indications of the use of positron emission/computed tomography for prostate, bladder and testes, and the potential role of this exam in radiotherapy planning. PMID:21507695

  9. Evaluation of the impact of metal artifacts in CT-based attenuation correction of positron emission tomography scans

    International Nuclear Information System (INIS)

    The quantitative ability of PET/CT allows the widespread use in clinical research and cancer staging. However, metal artifacts induced by high-density metal objects degrade the quality of CT images. These artifacts also propagate to the corresponding PET image and cause a false increase of 18F-FDG uptake near the metal implants when the CT-based attenuation correction (AC) is performed. In this study, we applied a model-based metal artifact reduction (MAR) algorithm to reduce the dark and bright streaks in the CT image and compared the differences between PET images with the general CT-based AC (G-AC) and the MAR-corrected-CT AC (MAR-AC). Results showed that the MAR algorithm effectively reduced the metal artifacts in the CT images of the ACR flangeless phantom and two clinical cases. The MAR-AC also removed the false-positive hot spot near the metal implants of the PET images. We conclude that the MAR-AC could be applied in clinical practice to improve the quantitative accuracy of PET images. Additionally, further use of PET/CT fusion images with metal artifact correction could be more valuable for diagnosis.

  10. Positron emission tomography: a new paradigm in cancer management

    International Nuclear Information System (INIS)

    The National Cancer Institute (NCI) is currently building a positron emission tomography facility that will house a cyclotron and a PET fusion scanner. lt should be operational as of december 2007, being a cancer dedicated national referral center, the NCI should provide both positron-emitting radiopharmaceuticals and medical services to institutions and patients nationwide. PET technology provides metabolic information that has been documented to be useful in patient care. The properties of positron decay allow accurate imaging of the in vivo distribution of positron-emitting radiopharmaceuticals. a wide array of positron-emitting radiopharmaceuticals has been used to characterize multiple physiologic and pathologic states. The major clinical PET applications are in cancer patients using fluorine-18 fluorodeoxyglucose (FDG). FDG, an analogue of glucose, accumulates in most tumors in a greater amount than it does in normal tissue. PET is being used in diagnosis and follow-up of several malignancies, and the list of articles supporting its use continues to grow. in this article, the instrumentation aspects of PET are described and most of the clinical applications in oncology are described

  11. 18F-fluorodeoxyglucose positron emission tomography in restaging of colorectal cancer. Evidence-based recommendations and cost-effectiveness

    International Nuclear Information System (INIS)

    Aim, method: Recommendations for the use of FDG-PET in relapsed colorectal cancer and the decision of reimbursement should base on published studies and on their level of evidence. Therefore, the PET-studies published between 1997 and 2002 were graded by the bias-criteria, by two rating-systems and by two classification-systems for the level of evidence according to AHCPR (Agency for Health Care Policy and Research) and VHA (Veterans Health Administration). Results: The recommendation for the use of PET in relapsed colorectal cancer reached the level IIa according to the AHCPR, corresponding to level B according to the VHA. The sensitivity and specificity of FDG-PET were 94% (95% CI: 91-96%) and 78% (95% CI: 69-86%), respectively. Staging was changed correctly in 27% of patients (95% CI: 24-30%). Staging by FDG-PET was incorrect in 4% of the patients (95% CI: 2-5%) compared with the conventionel methods. The additional use of PET changed the prospectively defined management plan for 34% of patients (95% CI: 31-38%). Either potentially curative operations were initiated in case of resectable tumour or futile operations were cancelled in case of multiple metastases. Conclusion: The 3-years-survival-rate following surgery would have exceeded 70% if the selection of patients had included an additional PET-examination. The correct selection of patients is requested in the daily routine as well as in the clinical implementation of neoadjuvant therapies to prevent a selection-bias from a suboptimal restaging without PET. (orig.)

  12. Positron Emission Tomography with Three-Dimensional Reconstruction

    International Nuclear Information System (INIS)

    The development of two different low-cost scanners for positron emission tomography (PET) based on 3D acquisition are presented. The first scanner consists of two rotating scintillation cameras, and produces quantitative images, which have shown to be clinically useful. The second one is a system with two opposed sets of detectors, based on the limited angle tomography principle, dedicated for mammographic studies. The development of low-cost PET scanners can increase the clinical impact of PET, which is an expensive modality, only available at a few centres world-wide and mainly used as a research tool. A 3D reconstruction method was developed that utilizes all the available data. The size of the data-sets is considerably reduced, using the single-slice rebinning approximation. The 3D reconstruction is divided into 1D axial deconvolution and 2D transaxial reconstruction, which makes it relatively fast. This method was developed for the rotating scanner, but was also implemented for multi-ring scanners with and without inter plane septa. An iterative 3D reconstruction method was developed for the limited angle scanner, based on the new concept of 'mobile pixels', which reduces the finite pixel errors and leads to an improved signal to noise ratio. 100 refs

  13. Positron emission tomography (PET) evaluation of abdominal aortic aneurysm (AAA)

    OpenAIRE

    SakalihasanN, Natzi; Van Damme, Hendrik; Gomez, P.; RIGO, PIERRE; Lapiere, C. M.; Nusgens, Betty; Limet, Raymond

    2002-01-01

    Background: aneurysmal disease is associated with all inflammatory Cell infiltrate and enzymatic degradation of the vessel wall. Aim of the study: to detect increased metabolic activity in abdominal aortic aneurysms (AAA) by means of positron emission tomography (PET-imaging). Study design: twenty-six patients with AAA underwent PET-imaging Results: in tell patients, PET-imaging revealed increased, fluoro-deoxy-glucose (18-FDG) uptake at the level of the aneurysm. Patients with positive PET-i...

  14. A Case of Corticobasal Degeneration Studied with Positron Emission Tomography

    OpenAIRE

    Nagasawa, H; T. Imamura; Nomura, H; Itoh, M; Ido, T.

    1993-01-01

    We measured cerebral blood flow, oxygen metabolism, glucose utilization, and dopamine metabolism in the brain of a patient with corticobasal degeneration using positron emission tomography (PET). The clinical picture is distinctive, comprising features referable to both cortical and basal ganglionic dysfunction. Brain imagings of glucose and dopamine metabolism can demonstrate greater abnormalities in the cerebral cortex and in the striatum contralateral to the more affected side than those o...

  15. Introducing Positron Emission Tomography (PET) in Clinical Practice

    OpenAIRE

    Janevik-Ivanovska, Emilija; Avmedovski, Fatmir; Yamamoto, Mayumi; Bhonsle, Uday

    2009-01-01

    Positron emission tomography (PET) is a major diagnostic imaging technique predominantly used in determining the presence and severity of cancers, neurological conditions, and cardiovascular diseases. It is currently the most effective way to check for cancer recurrences and it offers significant advantages over other forms of imaging such as computed tomography (CT) or magnetic resonance imaging (MRI) scans in detecting disease in many patients. In the USA, an estimated 1 129 900 clinical PE...

  16. ENVISION, developing Positron Emission Tomography for particle therapy

    CERN Multimedia

    2013-01-01

    Particle therapy is an advanced technique of cancer radiation therapy, using protons or other ions to target the cancerous mass. ENVISION aims at developing medical imaging tools to improve the dose delivery to the patient, to ensure a safer and more effective treatment. The animation illustrates the use of Positron Emission Tomography (PET) for monitoring the dose during treatment. Produced by: CERN KT/Life Sciences and ENVISION Project Management: Manuela Cirilli 3D animation: Jeroen Huijben, Nymus3d

  17. Nonhuman Primate Positron Emission Tomography Neuroimaging in Drug Abuse Research

    OpenAIRE

    Howell, Leonard Lee; Murnane, Kevin Sean

    2011-01-01

    Positron emission tomography (PET) neuroimaging in nonhuman primates has led to significant advances in our current understanding of the neurobiology and treatment of stimulant addiction in humans. PET neuroimaging has defined the in vivo biodistribution and pharmacokinetics of abused drugs and related these findings to the time course of behavioral effects associated with their addictive properties. With novel radiotracers and enhanced resolution, PET neuroimaging techniques have also charac...

  18. Positron emission holography: A new method of creating positron camera images

    International Nuclear Information System (INIS)

    By simulating the presence of a Fresnel zone plate in a camera designed for positron emission tomography (PET), a hologram can be synthesized which permits full three-dimensional images of the positron distribution in the original object to be rapidly constructed. The method requires no additional apparatus to a standard PET system, which is also operated in the usual way. The trajectory of each photon pair, detected in coincidence, is weighted as if it had passed through a zone plate optimised to suit the problem, before recording its intercept with a (single) plane to produce the hologram. The final image is created by calculating the diffraction pattern of monochromatic light passed through this hologram; it may also be created optically. The method is described in detail and its attractions discussed. Results are presented of some simple objects obtained from holograms produced from PET camera data, in comparison with images created by conventional back-projection processing of the same data. (orig.)

  19. European health telematics networks for positron emission tomography

    International Nuclear Information System (INIS)

    A pilot network of positron emission tomography centers across Europe has been setup employing telemedicine services. The primary aim is to bring all PET centers in Europe (and beyond) closer, by integrating advanced medical imaging technology and health telematics networks applications into a single, easy to operate health telematics platform, which allows secure transmission of medical data via a variety of telecommunications channels and fosters the cooperation between professionals in the field. The platform runs on PCs with Windows 2000/XP and incorporates advanced techniques for image visualization, analysis and fusion. The communication between two connected workstations is based on a TCP/IP connection secured by secure socket layers and virtual private network or jabber protocols. A teleconsultation can be online (with both physicians physically present) or offline (via transmission of messages which contain image data and other information). An interface sharing protocol enables online teleconsultations even over low bandwidth connections. This initiative promotes the cooperation and improved communication between nuclear medicine professionals, offering options for second opinion and training. It permits physicians to remotely consult patient data, even if they are away from the physical examination site

  20. European health telematics networks for positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kontaxakis, George [Universidad Politecnica de Madrid, ETSI Telecomunicacion, Madrid 28040 (Spain)]. E-mail: g.kontaxakis@upm.es; Pozo, Miguel Angel [Centro PET Complutense, Madrid 28040 (Spain); Universidad Complutense de Madrid, Instituto Pluridisciplinar, Madrid 28040 (Spain); Ohl, Roland [MedCom Gesellschaft fuer medizinische Bildverarbeitung mbH, Darmstadt 64283 (Germany); Visvikis, Dimitris [U650 INSERM, Lab. du Traitement de L' Information Medicale, University of Brest Occidentale, CHU Morvan, Brest 29609 (France); Sachpazidis, Ilias [Fraunhofer Institute for Computer Graphics, Darmstadt 64283 (Germany); Ortega, Fernando [Fundacion Instituto Valenciano de Oncologia, Valencia 46009 (Spain); Guerra, Pedro [Universidad Politecnica de Madrid, ETSI Telecomunicacion, Madrid 28040 (Spain); Cheze-Le Rest, Catherine [Dept. Medicine Nucleaire, CHU Morvan, Brest 29609 (France); Selby, Peter [MedCom Gesellschaft fuer medizinische Bildverarbeitung mbH, Darmstadt 64283 (Germany); Pan, Leyun [German Cancer Research Centre, Clinical Cooperation Unit Nuclear Medicine, Heidelberg 69120 (Germany); Diaz, Javier [Fundacion Instituto Valenciano de Oncologia, Valencia 46009 (Spain); Dimitrakopoulou-Strauss, Antonia [German Cancer Research Centre, Clinical Cooperation Unit Nuclear Medicine, Heidelberg 69120 (Germany); Santos, Andres [Universidad Politecnica de Madrid, ETSI Telecomunicacion, Madrid 28040 (Spain); Strauss, Ludwig [German Cancer Research Centre, Clinical Cooperation Unit Nuclear Medicine, Heidelberg 69120 (Germany); Sakas, Georgios [MedCom Gesellschaft fuer medizinische Bildverarbeitung mbH, Darmstadt 64283 (Germany); Fraunhofer Institute for Computer Graphics, Darmstadt 64283 (Germany)

    2006-12-20

    A pilot network of positron emission tomography centers across Europe has been setup employing telemedicine services. The primary aim is to bring all PET centers in Europe (and beyond) closer, by integrating advanced medical imaging technology and health telematics networks applications into a single, easy to operate health telematics platform, which allows secure transmission of medical data via a variety of telecommunications channels and fosters the cooperation between professionals in the field. The platform runs on PCs with Windows 2000/XP and incorporates advanced techniques for image visualization, analysis and fusion. The communication between two connected workstations is based on a TCP/IP connection secured by secure socket layers and virtual private network or jabber protocols. A teleconsultation can be online (with both physicians physically present) or offline (via transmission of messages which contain image data and other information). An interface sharing protocol enables online teleconsultations even over low bandwidth connections. This initiative promotes the cooperation and improved communication between nuclear medicine professionals, offering options for second opinion and training. It permits physicians to remotely consult patient data, even if they are away from the physical examination site.

  1. Positron emission tomography scans on kanji and kana

    International Nuclear Information System (INIS)

    We reanalyzed our positron emission tomography (PET) study on reading of Japanese kanji (morphogram) words, kana (phonogram) words and kana nonwords, using Statistical Parametric Mapping (SPM). The basal occipital and occipito-temporal areas were activated in common, among which activity was most pronounced in the fusiform/inferior temporal gyri with kanji and in the inferior occipital gyrus with kana. The results were consistent with the clinical observations that damage to the posterior inferior temporal cortex including the fusiform/inferior temporal gyri causes alexia with agraphia for kanji, whereas damage to the posterior occipital area including the inferior occipital gyrus causes pure alexia for kana. Bases on the present results and the lesion studies, a dual-route hypothesis that modifies Iwata's model of reading about the Japanese language was proposed. That is, the middle occipital gyrus, deep perisylvian temporoparietal cortex and posterior temporal gyrus constitute a dorsal route for reading and process phonology for words, whereas the inferior occipital, fusiform and posterior inferior temporal gyri constitute a ventral route for reading and process orthography and lexico-semantics for words. The ventral route may gain dominance in reading, according as a word is repeatedly presented. (author)

  2. Characterization of nontransmural myocardial infarction by positron-emission tomography

    International Nuclear Information System (INIS)

    The present study was performed to determine whether positron emission tomography (PET) performed after i.v. 11C-palmitate permits detection and characterization of nontransmural myocardial infarction. PET was performed after the i.v. injection of 11C-palmitate in 10 normal subjects, 24 patients with initial nontransmural myocardial infarction (defined electrocardiographically), and 22 patients with transmural infarction. Depressed accumulation of 11C-palmitate was detected with sagittal, coronal and transverse reconstructions, and quantified based on 14 contiguous transaxial reconstructions. Defects with homogeneously intense depression of accumulation of tracer were detected in all 22 patients with transmural infarction (100%). Abnormalities of the distribution of 11C-palmitate in the myocardium were detected in 23 patients with nontransmural infarction (96%). Thallium scintigrams were abnormal in only 11 of 18 patients with nontransmural infarction (61%). Tomographically estimated infarct size was greater among patients with transmural infarction (50.4 +/- 7.8 PET-g-Eq/m2 [+/- SEM SEM]) compared with those with nontransmural infarction (19 +/- 4 PET-g-Eq, p less than 0.01). Residual accumulation of 11C-palmitate within regions of infarction was more intensely depressed among patients with transmural compared to nontransmural infarction (33 +/- 1 vs 39 +/- 1% maximal myocardial radioactivity, p less than 0.01). Thus, PET and metabolic imaging with 11C-palmitate is a sensitive means of detecting, quantifying and characterizing nontransmural and transmural myocardial infarction

  3. European health telematics networks for positron emission tomography

    Science.gov (United States)

    Kontaxakis, George; Pozo, Miguel Angel; Ohl, Roland; Visvikis, Dimitris; Sachpazidis, Ilias; Ortega, Fernando; Guerra, Pedro; Cheze-Le Rest, Catherine; Selby, Peter; Pan, Leyun; Diaz, Javier; Dimitrakopoulou-Strauss, Antonia; Santos, Andres; Strauss, Ludwig; Sakas, Georgios

    2006-12-01

    A pilot network of positron emission tomography centers across Europe has been setup employing telemedicine services. The primary aim is to bring all PET centers in Europe (and beyond) closer, by integrating advanced medical imaging technology and health telematics networks applications into a single, easy to operate health telematics platform, which allows secure transmission of medical data via a variety of telecommunications channels and fosters the cooperation between professionals in the field. The platform runs on PCs with Windows 2000/XP and incorporates advanced techniques for image visualization, analysis and fusion. The communication between two connected workstations is based on a TCP/IP connection secured by secure socket layers and virtual private network or jabber protocols. A teleconsultation can be online (with both physicians physically present) or offline (via transmission of messages which contain image data and other information). An interface sharing protocol enables online teleconsultations even over low bandwidth connections. This initiative promotes the cooperation and improved communication between nuclear medicine professionals, offering options for second opinion and training. It permits physicians to remotely consult patient data, even if they are away from the physical examination site.

  4. Positron emission tomography scans on kanji and kana

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, Yasuhisa [Mitsui Memorial Hospital, Tokyo (Japan)

    2002-12-01

    We reanalyzed our positron emission tomography (PET) study on reading of Japanese kanji (morphogram) words, kana (phonogram) words and kana nonwords, using Statistical Parametric Mapping (SPM). The basal occipital and occipito-temporal areas were activated in common, among which activity was most pronounced in the fusiform/inferior temporal gyri with kanji and in the inferior occipital gyrus with kana. The results were consistent with the clinical observations that damage to the posterior inferior temporal cortex including the fusiform/inferior temporal gyri causes alexia with agraphia for kanji, whereas damage to the posterior occipital area including the inferior occipital gyrus causes pure alexia for kana. Bases on the present results and the lesion studies, a dual-route hypothesis that modifies Iwata's model of reading about the Japanese language was proposed. That is, the middle occipital gyrus, deep perisylvian temporoparietal cortex and posterior temporal gyrus constitute a dorsal route for reading and process phonology for words, whereas the inferior occipital, fusiform and posterior inferior temporal gyri constitute a ventral route for reading and process orthography and lexico-semantics for words. The ventral route may gain dominance in reading, according as a word is repeatedly presented. (author)

  5. Recent innovations in the detection systems of Positron Emission Tomography

    International Nuclear Information System (INIS)

    Since the recognition of the clinical value of Positron Emission Tomography (PET) for the diagnosis and staging of several cancers, the PET systems have evolved to systems associating PET and Computed Tomography (CT). The main constraint for clinical imaging is to reduce the acquisition duration. As a consequence, PET detectors are faster and emit more light than the BGO crystal used previously. These detectors allow an improvement of the count rate performance of the PET systems, reducing the scattered and the random events while increasing the true events at high activity concentration. Among the new crystals, some allow measuring the time of flight of the annihilation photons. This measurement further improves the performance of the systems. The spatial resolution of clinical PET systems is still equal to 5 mm at best. High spatial resolution PET systems dedicated to small animal imaging have been developed. These systems use similar crystal materials as the clinical systems. However, in order to permit spatial resolution close to 1 mm, the crystal elements have much smaller transverse dimensions than that of clinical systems. The detectors are compact using position sensitive photomultipliers or photodiodes. In order to preserve the uniformity of the spatial resolution over the transverse field of view of the tomography, solutions allowing the measurement of the depth of interaction of the photons in the crystal have been designed. New compact detectors based on semi conductors are currently investigated. (author)

  6. Biological imaging in radiation therapy: role of positron emission tomography

    International Nuclear Information System (INIS)

    In radiation therapy (RT), staging, treatment planning, monitoring and evaluation of response are traditionally based on computed tomography (CT) and magnetic resonance imaging (MRI). These radiological investigations have the significant advantage to show the anatomy with a high resolution, being also called anatomical imaging. In recent years, so called biological imaging methods which visualize metabolic pathways have been developed. These methods offer complementary imaging of various aspects of tumour biology. To date, the most prominent biological imaging system in use is positron emission tomography (PET), whose diagnostic properties have clinically been evaluated for years. The aim of this review is to discuss the valences and implications of PET in RT. We will focus our evaluation on the following topics: the role of biological imaging for tumour tissue detection/delineation of the gross tumour volume (GTV) and for the visualization of heterogeneous tumour biology. We will discuss the role of fluorodeoxyglucose-PET in lung and head and neck cancer and the impact of amino acids (AA)-PET in target volume delineation of brain gliomas. Furthermore, we summarize the data of the literature about tumour hypoxia and proliferation visualized by PET. We conclude that, regarding treatment planning in radiotherapy, PET offers advantages in terms of tumour delineation and the description of biological processes. However, to define the real impact of biological imaging on clinical outcome after radiotherapy, further experimental, clinical and cost/benefit analyses are required. (topical review)

  7. Reconstruction Algorithms for Positron Emission Tomography and Single Photon Emission Computed Tomography and their Numerical Implementation

    CERN Document Server

    Fokas, A S; Marinakis, V

    2004-01-01

    The modern imaging techniques of Positron Emission Tomography and of Single Photon Emission Computed Tomography are not only two of the most important tools for studying the functional characteristics of the brain, but they now also play a vital role in several areas of clinical medicine, including neurology, oncology and cardiology. The basic mathematical problems associated with these techniques are the construction of the inverse of the Radon transform and of the inverse of the so called attenuated Radon transform respectively. We first show that, by employing mathematical techniques developed in the theory of nonlinear integrable equations, it is possible to obtain analytic formulas for these two inverse transforms. We then present algorithms for the numerical implementation of these analytic formulas, based on approximating the given data in terms of cubic splines. Several numerical tests are presented which suggest that our algorithms are capable of producing accurate reconstruction for realistic phanto...

  8. Positron emission tomography and cerebral metabolism

    International Nuclear Information System (INIS)

    The association of new methods of labelling with short lived radioisotopes and of visualisation 'in vivo' of these labelled molecules by emission tomography, provide the possibility of studying brain metabolism at different levels. Two examples will illustrate the possibilities of this methodology. Cerebral metabolism of methionine-11C in phenylketonutic patients: The cerebral uptake of methionine was measured in 24 PKU children aged 1 to 40 months on a low protein diet. Ten of them were examined twice at intervals of several months. Stopping the diet for one week leads to an increase in blood phenylalanine and to a significant important decrease in brain uptake of labelled methionine. Futhermore, for children under treatment having a low phenylalanine blood concentration, brain uptake of methionine decreases with age between 1 and 40 months. These results suggest that the treatment of this disease should be started as soon as possible after birth. Cerebral metabolism of psychoactive drugs: The study of the brain distribution and kinetics of psychoactive drugs may help in understanding their mode of action. Chlorpromazine- 11C was administered i.v. to schyzophrenic patients not previously treated with neuroleptics. In all patients the brain uptake of the drug was high and rapid, and was localized mainly in the grey matter, probably in proportion to the blood flow. Non-specific binding of this drug to brain proteins prevented visualization of specific binding to dopaminergic or αnor-adrenergic receptors. Specific receptor binding of benzodiazepines was however visualized in the brain of baboons after injection of 11C-flunitrazepam (specific activity = 600 Ci/μmole) and subsequent displacement of this radioactive ligand by a pharmacological dose of Lorazepam

  9. Software development for modeling positrons emission tomograph scanners

    International Nuclear Information System (INIS)

    The Geant4 Application for Tomographic Emission (GATE) is an international platform recognized and used to develop Computational Model Exposure (CME) in the context of Nuclear Medicine, although currently there are dedicated modules for applications in Radiotherapy and Computed Tomography (CT). GATE uses Monte Carlo (MC) methods, and has a scripting language of its own. The writing of scripts for simulation of a PET scanner in GATE involves a number of interrelated steps, and the accuracy of the simulation is dependent on the correct setup of the geometries involved, since the physical processes depend on them, as well as the modeling of electronic detectors in module Digitizer, for example. The manual implementation of this setup can be a source of errors, especially for users without experience in the field of simulations or without any previous knowledge of a programming language, and also due to the the fact that the modeling process in GATE still remains bounded to LINUX / UNIX based systems, an environment only familiar to a few. This becomes an obstacle for beginners and prevents the use of GATE by a larger number of users interested in optimizing their experiments and/or clinical protocols through a more accessible, fast and friendly application. The objective of this work is therefore to develop a user-friendly software for the modeling of Positron Emission Tomography called GUIGATE (Graphical User Interface for GATE), with specific modules dedicated to quality control in PET scanners. The results exhibit the features available in this first version of GUIGATE, present in a set of windows that allow users to create their input files, perform and display in real time the model and analyze its output file in a single environment, allowing so intuitively access the entire architecture of the GATE simulation and to CERN's data analyzer, the ROOT. (author)

  10. Clinical cardiac positron emission tomography: State of the art

    International Nuclear Information System (INIS)

    Cardiac positron emission tomography (PET) has evolved rapidly from a relatively esoteric research tool into clinical applications providing unique, quantitative information on myocardial perfusion, metabolism, and cell membrane function and having a potentially significant impact on cardiovascular medicine. Although there are many different positron radionuclides for imaging diverse myocardial behavior, three radionuclides have reached accepted clinical utility. Cardiac PET using nitrogen-13-ammonia, rubidium-82, and fluoro-18-deoxyglucose has proved accurate and definitive in multiple university and private-practice sites for diagnosing and assessing severity and location of coronary artery disease in symptomatic or asymptomatic patients, for identifying injured but viable myocardium potentially salvageable by revascularization, and for ruling out clinically significant coronary artery stenosis with a high specificity in patients who might otherwise undergo coronary arteriography to document the absence of significant disease. 89 references

  11. Investigation of granular impact using positron emission particle tracking

    KAUST Repository

    Marston, Jeremy O.

    2015-04-01

    We present results from an experimental study of granular impact using a combination of high-speed video and positron emission particle tracking (PEPT). The PEPT technique exploits the annihilation of photons from positron decay to determine the position of tracer particles either inside a small granular bed or attached to the object which impacts the bed. We use dense spheres as impactors and the granular beds are comprised of glass beads which are fluidised to achieve a range of different initial packing states. For the first time, we have simultaneously investigated both the trajectory of the sphere, the motion of particles in a 3-D granular bed and particles which jump into the resultant jet, which arises from the collapse of the cavity formed by the impacting sphere.

  12. Positron Emission Tomography in Breast Cancer

    OpenAIRE

    Jose Luis Vercher-Conejero; Laura Pelegrí-Martinez; Diego Lopez-Aznar; María del Puig Cózar-Santiago

    2015-01-01

    Gradually, FDG-PET/CT has been strengthening within the diagnostic algorithms of oncological diseases. In many of these, PET/CT has shown to be useful at different stages of the disease: diagnosis, staging or re-staging, treatment response assessment, and recurrence. Some of the advantages of this imaging modality versus CT, MRI, bone scan, mammography, or ultrasound, are based on its great diagnostic capacity since, according to the radiopharmaceutical used, it reflects metabolic changes tha...

  13. Positron Emission Tomography in Breast Cancer

    Science.gov (United States)

    Vercher-Conejero, Jose Luis; Pelegrí-Martinez, Laura; Lopez-Aznar, Diego; Cózar-Santiago, María del Puig

    2015-01-01

    Gradually, FDG-PET/CT has been strengthening within the diagnostic algorithms of oncological diseases. In many of these, PET/CT has shown to be useful at different stages of the disease: diagnosis, staging or re-staging, treatment response assessment, and recurrence. Some of the advantages of this imaging modality versus CT, MRI, bone scan, mammography, or ultrasound, are based on its great diagnostic capacity since, according to the radiopharmaceutical used, it reflects metabolic changes that often occur before morphological changes and therefore allows us to stage at diagnosis. Moreover, another advantage of this technique is that it allows us to evaluate the whole body so it can be very useful for the detection of distant disease. With regard to breast cancer, FDG-PET/CT has proven to be important when recurrence is suspected or in the evaluation of treatment response. The technological advancement of PET equipment through the development of new detectors and equipment designed specifically for breast imaging, and the development of more specific radiopharmaceuticals for the study of the different biological processes of breast cancer, will allow progress not only in making the diagnosis of the disease at an early stage but also in enabling personalized therapy for patients with breast cancer. PMID:26854143

  14. Positron Emission Tomography in Breast Cancer

    Directory of Open Access Journals (Sweden)

    Jose Luis Vercher-Conejero

    2015-03-01

    Full Text Available Gradually, FDG-PET/CT has been strengthening within the diagnostic algorithms of oncological diseases. In many of these, PET/CT has shown to be useful at different stages of the disease: diagnosis, staging or re-staging, treatment response assessment, and recurrence. Some of the advantages of this imaging modality versus CT, MRI, bone scan, mammography, or ultrasound, are based on its great diagnostic capacity since, according to the radiopharmaceutical used, it reflects metabolic changes that often occur before morphological changes and therefore allows us to stage at diagnosis. Moreover, another advantage of this technique is that it allows us to evaluate the whole body so it can be very useful for the detection of distant disease. With regard to breast cancer, FDG-PET/CT has proven to be important when recurrence is suspected or in the evaluation of treatment response. The technological advancement of PET equipment through the development of new detectors and equipment designed specifically for breast imaging, and the development of more specific radiopharmaceuticals for the study of the different biological processes of breast cancer, will allow progress not only in making the diagnosis of the disease at an early stage but also in enabling personalized therapy for patients with breast cancer.

  15. A Spartan3E-based low-cost system for gamma-ray detection in small single photon emission computed tomography or positron emission tomography systems

    Science.gov (United States)

    Fysikopoulos, E.; Georgiou, M.; Efthimiou, N.; David, S.; Loudos, G.; Matsopoulos, G.

    2011-11-01

    The development and assessment of a readout system based on field programmable gate arrays (FPGA) for dedicated nuclear medicine cameras is presented. We have used Xilinx Spartan3E starter kit, which is one of the simplest FPGA evaluation boards. The aim of this work is to offer a simple, open source, data acquisition tool, which provides accurate results for nuclear imaging applications. The system has been evaluated using three different experimental setups: pulses from two position-sensitive photo-multipliers (PSPMTs) and a silicon photo-multiplier (SiPM) were recorded, using 99mTc sources. Two dual channel, external, 12 bit analog to digital converters with a sampling rate of 1 Msps per channel were used. The tool was designed using Xilinx's embedded development kit and was based in Xilinx's Microblaze soft-core processor. A reference multiparameter-based data acquisition system using nuclear instrumentation modules was used for the evaluation of the proposed system. A number of tests were carried out to assess different algorithms for pulse maximum estimation and Gaussian fitting provided optimal results. The results have shown that the FPGA data acquisition system (i) provides accurate digitization of the PSPMT anode signals under various conditions and (ii) gives similar energy spectra when SiPMs are used.

  16. A new positron emission particle tracking facility at iThemba LABS

    International Nuclear Information System (INIS)

    Positron emission particle tracking (PEPT) has become a powerful tool for in-situ characterisation and visualization of particulate flow within aggressive industrial environments, such as tumbling mills and powder mixers. PEPT is based on the tracking of a single tracer particle which has been labelled with a radionuclide that decays via beta-plus decay. The location of the particle is obtained by the triangulation of events associated with the detection of pairs of annihilation gamma rays in a modified 'positron camera.' One of the challenges facing PEPT is associated with labelling particles smaller than 100 μm which would allow studies in systems of finer particulate flow, such as flotation cells. The Positron Imaging Centre at the University of Birmingham is currently the only operational PEPT facility in the world. PEPT Cape Town will shortly become operational at iThemba LABS, South Africa. (author)

  17. Methods and clinical applications of positron emission tomography in endocrinology

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) allows to detect in coincidence photons issued from annihilation between positrons and electrons nearby situated. Tomographic detection (plane by plane) and tomographic reconstruction will lead to the quantitation of radioactive distribution per voxel, in the organ of interest. Recent tomographs can acquire simultaneously several transaxial slices, with a high sensitivity and a spatial resolution of 3-5 mm. Commonly used positron emitters have a short half-life: 2, 10, 20 and 110 min for 150, 13N, 11C and 18F, respectively. The use of these isotopes requires on line production of radionuclides and synthesis of selected molecules. In endocrinology, PET allows among others to study noninvasively the receptor density of hormonodependent neoplasms such as breast, uterus, prostate tumors and prolactinomas. These last tumors represent a particular entity because of several combined characteristics: high turnover rate of amino acids, high density of dopaminergic receptors and response to bromocriptine (analogue of dopamine inhibiting the secretion of prolactine) in relation to the level of receptors. Because PET permits to evaluate the density of dopaminergic receptors and the metabolism of amino acids, theoretical response of the prolactinoma to bromocriptin can be predicted, the achieved therapeutic efficacy can be estimated and the long-term follow up of tumor growth can be assessed. This example illustrates the clinical value of PET in endocrinology

  18. The investigation of cerebrovascular disorders with positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) provides a non-invasive, regional, in vivo method to measure physiological parameters including cerebral blood flow, glucose and oxygen metabolism, blood volume, and pH. Measurement of these parameters not only enables a more complete understanding of the pathophysiology of acute cerebral ischemia and infarction, but provides objective criteria with which to better manage patients. This chapter will first discuss PET methodology and tracer techniques used in the investigation of patients with cerebrovascular disease and then describe the progress that has already resulted from applying these methods. 73 refs.; 7 figs

  19. Positron emission tomography: diagnostic imaging on a molecular level

    International Nuclear Information System (INIS)

    In human medicine positron emission tomography (PET) is a modern diagnostic imaging method. In the present paper we outline the physical principles of PET and give an overview over the main clinic fields where PET is being used, such as neurology, cardiology and oncology. Moreover, we present a current project in veterinary medicine (in collaboration with the Paul Scherrer Institute and the University Hospital Zurich), where a hypoxia tracer is applied to dogs and cats suffering from spontaneous tumors. Finally new developments in the field of PET were discussed

  20. Kinetic modeling in pre-clinical positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kuntner, Claudia [AIT Austrian Institute of Technology GmbH, Seibersdorf (Austria). Biomedical Systems, Health and Environment Dept.

    2014-07-01

    Pre-clinical positron emission tomography (PET) has evolved in the last few years from pure visualization of radiotracer uptake and distribution towards quantification of the physiological parameters. For reliable and reproducible quantification the kinetic modeling methods used to obtain relevant parameters of radiotracer tissue interaction are important. Here we present different kinetic modeling techniques with a focus on compartmental models including plasma input models and reference tissue input models. The experimental challenges of deriving the plasma input function in rodents and the effect of anesthesia are discussed. Finally, in vivo application of kinetic modeling in various areas of pre-clinical research is presented and compared to human data.

  1. Design of a volume-imaging positron emission tomograph

    International Nuclear Information System (INIS)

    Progress is reported in several areas of design of a positron volume imaging tomograph. As a means of increasing the volume imaged and the detector packing fraction, a lens system of detector light coupling is considered. A prototype layered scintillator detector demonstrates improved spatial resolution due to a unique Compton rejection capability.The conceptual design of a new mechanism for measuring scattered radiation during emission scans has been tested by Monte Carlo simulation. The problem of how to use effectively the resulting sampled scattered radiation projections is presented and discussed

  2. Positron Emission Tomography Imaging of Regional Pulmonary Perfusion and Ventilation

    OpenAIRE

    Musch, Guido; Venegas, Jose G.

    2005-01-01

    Positron emission tomography (PET) imaging is a noninvasive, quantitative method to assess pulmonary perfusion and ventilation in vivo. The core of this article focuses on the use of [13N]nitrogen (13N2) and PET to assess regional gas exchange. Regional perfusion and shunt can be measured with the 13N2–saline bolus infusion technique. A bolus of 13N2, dissolved in saline solution, is injected intravenously at the start of a brief apnea, while the tracer kinetics in the lung is measured by a s...

  3. Use of positron emission tomography in colorectal cancer

    International Nuclear Information System (INIS)

    The value of PET (Positron Emission Tomography) in colorectal cancer is presented. PET is a novel technique that uses F-18-FDG (fluorodeoxiglucose) to assess glucose metabolism by whole body imaging. It has been demonstrated that malignant cells have both increase of glucose uptake and utilization. In colorectal cancer, PET is indicated for staging, assess recurrence, liver metastasis and treatment follow-up. PET is more sensitive and specific than CT (Computed Tomography) and is cost effective. In 30% of cases PET may change patient management, avoiding unnecessary procedures (au)

  4. Imaging of brain activity by positron emission tomography

    International Nuclear Information System (INIS)

    Brain function is associated with regional energy metabolism and blood flow increase. Such brain activity is visualized by using external scintigraphy. Positron emission tomography (PET) is the currently available most superior technique, allowing three-dimensional imaging of subtle blood flow. In this article, imaging methods and application of PET are discussed in terms of the following items: (1) measurement of cerebral glucose consumption, (2) PET in persons with visual impairment, (3) association between brain function and regional cerebral blood flow, (4) measurement of cerebral blood flow, (5) method for decreasing noise in PET imaging, (6) anatomic standardization of PET images, and (7) speech load and regional cerebral activity images. (N.K.)

  5. Application of positron emission tomography in industrial research

    International Nuclear Information System (INIS)

    Positron Emission computed Tomography (PET) is a relatively new imaging technique, exploiting the 511 keV annihilation radiation characteristic of positron emitters. Although exclusively used till now in the field of nuclear medicine, the application of PET for the non-invasive, in-situ visualisation of processes of industrial interest is challenging, because PET can in principle be used to obtain quantitative, 2D/3D images of the flow and distribution of fluids inside process units, whose steel walls may be up to several centimeters thick. With the aid of a NeuroECAT positron tomographer the PET technique has been utilised to image important (model) processes in the petrochemical industry, using physical labelling of the phase to be imaged. First, the displacement of a brine/surfactant phase, labelled with 66Ga-EDTA, in a piece of reservoir rock was imaged. Secondly, the dehydration of water-in-oil emulsions was monitored dynamically by labelling the water phase with 68Ga-EDTA. The second study in particular demonstrates that in the presence of noisy data the image reconstruction method utilised strongly influences the results obtained. With the advent of PET in nuclear medicine the availability of short-lived positron emitting nuclides like 11C (t1/2 = 20 min), 13N (t1/2 = 10 min) and 150 (t1/2 = 2 min) has increased considerably, allowing the investigation of industrially important reactions by chemical labelling. Utilising the NeuroECAT in a special mode, the catalytic oxidation of carbon monoxide could be imaged in a model tubular reactor by using 11C-labelled CO, providing information about the kinetics of the individual reaction steps and interactions and about the degree of occupation of catalytically active sites. (author)

  6. Theranostic unimolecular micelles based on brush-shaped amphiphilic block copolymers for tumor-targeted drug delivery and positron emission tomography imaging.

    Science.gov (United States)

    Guo, Jintang; Hong, Hao; Chen, Guojun; Shi, Sixiang; Nayak, Tapas R; Theuer, Charles P; Barnhart, Todd E; Cai, Weibo; Gong, Shaoqin

    2014-12-24

    Brush-shaped amphiphilic block copolymers were conjugated with a monoclonal antibody against CD105 (i.e., TRC105) and a macrocyclic chelator for (64)Cu-labeling to generate multifunctional theranostic unimolecular micelles. The backbone of the brush-shaped amphiphilic block copolymer was poly(2-hydroxyethyl methacrylate) (PHEMA) and the side chains were poly(L-lactide)-poly(ethylene glycol) (PLLA-PEG). The doxorubicin (DOX)-loaded unimolecular micelles showed a pH-dependent drug release profile and a uniform size distribution. A significantly higher cellular uptake of TRC105-conjugated micelles was observed in CD105-positive human umbilical vein endothelial cells (HUVEC) than nontargeted micelles due to CD105-mediated endocytosis. In contrast, similar and extremely low cellular uptake of both targeted and nontargeted micelles was observed in MCF-7 human breast cancer cells (CD105-negative). The difference between the in vivo tumor accumulation of (64)Cu-labeled TRC105-conjugated micelles and that of nontargeted micelles was studied in 4T1 murine breast tumor-bearing mice, by serial positron emission tomography (PET) imaging and validated by biodistribution studies. These multifunctional unimolecular micelles offer pH-responsive drug release, noninvasive PET imaging capability, together with both passive and active tumor-targeting abilities, thus making them a desirable nanoplatform for cancer theranostics. PMID:24628452

  7. A positron emission tomograph based on LSO-APD modules with a sampling ADC read-out system for a students' advanced laboratory course

    International Nuclear Information System (INIS)

    A one-day laboratory course on positron emission tomography (PET) for the education of physics students and PhD students in medical physics has been set up. In the course, the physical background and the principles of a PET scanner are introduced. Course attendees set the system in operation, calibrate it using a 22Na point source and reconstruct different source geometries filled with 18F. The PET scanner features an individual channel read-out of 96 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to avalanche photodiodes (APD). The analog data of each APD are digitized by fast sampling analog to digital converters (SADC) and processed within field programmable gate arrays (FPGA) to extract amplitudes and time stamps. All SADCs are continuously sampling with a precise rate of 80 MHz, which is synchronous for the whole system. The data is transmitted via USB to a Linux PC, where further processing and the image reconstruction are performed. The course attendees get an insight into detector techniques, modern read-out electronics, data acquisition and PET image reconstruction. In addition, a short introduction to some common software applications used in particle and high energy physics is part of the course. (orig.)

  8. A positron emission tomograph based on LSO-APD modules with a sampling ADC read-out system for a students' advanced laboratory course

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Florian R.; Mann, Alexander B. [Technische Univ. Muenchen, Garching (Germany). Physik-Department E18; Technische Univ. Muenchen, Klinikum rechts der Isar (Germany). Nuklearmedizinische Klinik und Poliklinik; Konorov, Igor; Paul, Stephan [Technische Univ. Muenchen, Garching (Germany). Physik-Department E18; Delso, Gaspar; Ziegler, Sibylle I. [Technische Univ. Muenchen, Klinikum rechts der Isar (Germany). Nuklearmedizinische Klinik und Poliklinik

    2012-07-01

    A one-day laboratory course on positron emission tomography (PET) for the education of physics students and PhD students in medical physics has been set up. In the course, the physical background and the principles of a PET scanner are introduced. Course attendees set the system in operation, calibrate it using a {sup 22}Na point source and reconstruct different source geometries filled with {sup 18}F. The PET scanner features an individual channel read-out of 96 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to avalanche photodiodes (APD). The analog data of each APD are digitized by fast sampling analog to digital converters (SADC) and processed within field programmable gate arrays (FPGA) to extract amplitudes and time stamps. All SADCs are continuously sampling with a precise rate of 80 MHz, which is synchronous for the whole system. The data is transmitted via USB to a Linux PC, where further processing and the image reconstruction are performed. The course attendees get an insight into detector techniques, modern read-out electronics, data acquisition and PET image reconstruction. In addition, a short introduction to some common software applications used in particle and high energy physics is part of the course. (orig.)

  9. Positron and positronium annihilation in silica-based thin films studied by a pulsed positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, R. E-mail: r-suzuki@aist.go.jp; Ohdaira, T.; Kobayashi, Y.; Ito, K.; Shioya, Y.; Ishimaru, T

    2003-11-01

    Positron and positronium annihilation in silica-based thin films has been investigated by means of measurement techniques with a monoenergetic pulsed positron beam. The age-momentum correlation study revealed that positron annihilation in thermally grown SiO{sub 2} is basically the same as that in bulk amorphous SiO{sub 2} while o-Ps in the PECVD grown SiCOH film predominantly annihilate with electrons of C and H at the microvoid surfaces. We also discuss time-dependent three-gamma annihilation in porous low-k films by two-dimensional positron annihilation lifetime spectroscopy.

  10. The electronics system for the LBNL positron emission mammography (PEM) camera

    CERN Document Server

    Moses, W W; Baker, K; Jones, W; Lenox, M; Ho, M H; Weng, M

    2001-01-01

    Describes the electronics for a high-performance positron emission mammography (PEM) camera. It is based on the electronics for a human brain positron emission tomography (PET) camera (the Siemens/CTI HRRT), modified to use a detector module that incorporates a photodiode (PD) array. An application-specified integrated circuit (ASIC) services the photodetector (PD) array, amplifying its signal and identifying the crystal of interaction. Another ASIC services the photomultiplier tube (PMT), measuring its output and providing a timing signal. Field-programmable gate arrays (FPGAs) and lookup RAMs are used to apply crystal-by-crystal correction factors and measure the energy deposit and the interaction depth (based on the PD/PMT ratio). Additional FPGAs provide event multiplexing, derandomization, coincidence detection, and real-time rebinning. Embedded PC/104 microprocessors provide communication, real-time control, and configure the system. Extensive use of FPGAs make the overall design extremely flexible, all...

  11. The electronics system for the LBNL positron emission tomography (PEM) camera

    OpenAIRE

    Moses, W. W.; Young, J.W.; Baker, K.; Jones, W; Lenox, M.; Ho, M. H.; Weng, M.

    2000-01-01

    We describe the electronics for a high performance Positron Emission Mammography (PEM) camera. It is based on the electronics for a human brain PET camera (the Siemens/CTI HRRT), modified to use a detector module that incorporates a photodiode (PD) array. An ASIC services the PD array, amplifying its signal and identifying the crystal of interaction. Another ASIC services the photomultiplier tube (PMT), measuring its output and providing a timing signal. Field programmable gate arrays (...

  12. The establishment of crystal position look-up table for positron emission tomography with block detectors

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A method has been developed to establish the crystal position look-up table for positron emission tomography with block detectors. It is based on the principle that the counts in crystal position histogram obey the Gaussian mixture model (GMM). This method has taken full consideration of the characteristics of the GMM and the detector itself. The experimental results have proved that it is simple, reliable, and universal.

  13. Basic principles of 18F-fluoro-deoxyglucose positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography uses photons to receive regional information about dynamic, physiologic, and biochemical processes in the living body. A positron decay is measured indirectly by the simultaneous registration of both gamma rays created by the annihilation. The event is counted, if two directly opposite located detectors register gamma rays in coincidence. Unfortunately the detectors of a positron emission tomography system do not register only true coincident events. There are also scattered and random coincidences. Different types of positron tomographs are presented and scintillation crystals, which are in use for positron emission tomography are discussed. The 2D- and 3D-acquisition methods are described as well as preprocessing methods, such as correction for attenuation, scatter and dead time. For quantification the relative parameter standard uptake value (SUV) is explained. Finally hybrid systems, such as combined positron emission tomography/computed tomography scanners and the use of computed tomography data for attenuation correction are introduced. (author)

  14. A controlled study of positron-emission-tomography and positron-emission-tomography/computed tomography in differential diagnosis of solitary pulmonary nodules-report of 60 cases

    Institute of Scientific and Technical Information of China (English)

    DING Qi-yong; HUA Yan-qing; ZHANG Guo-zhen; ZHAO Jun; GUAN Yi-hui; GE Xiao-jun; MAO Ding-biao; ZUO Chuan-tao

    2005-01-01

    @@ The differential diagnosis of solitary pulmonary nodules (SPNs) remains a challenge. It is acknowledged that combining positron-emission tomography (PET) and computed tomography (CT) offers the most reliable noninvasive method for the diagnosis of SPNs.

  15. 4.5 Tesla magnetic field reduces range of high-energy positrons -- Potential implications for positron emission tomography

    International Nuclear Information System (INIS)

    The authors have theoretically and experimentally investigated the extent to which homogeneous magnetic fields up to 7 Tesla reduce the spatial distance positrons travel before annihilation (positron range). Computer simulations of a noncoincident detector design using a Monte Carlo algorithm calculated the positron range as a function of positron energy and magnetic field strength. The simulation predicted improvements in resolution, defined as full-width at half-maximum (FWHM) of the line-spread function (LSF) for a magnetic field strength up to 7 Tesla: negligible for F-18, from 3.35 mm to 2.73 mm for Ga-68 and from 3.66 mm to 2.68 mm for Rb-82. Also a substantial noise suppression was observed, described by the full-width at tenth-maximum (FWTM) for higher positron energies. The experimental approach confirmed an improvement in resolution for Ga-68 from 3.54 mm at 0 Tesla to 2.99 mm FWHM at 4.5 Tesla and practically no improvement for F-18 (2.97 mm at 0 Tesla and 2.95 mm at 4.5 Tesla). It is concluded that the simulation model is appropriate and that a homogeneous static magnetic field of 4.5 Tesla reduces the range of high-energy positrons to an extent that may improve spatial resolution in positron emission tomography

  16. 77 FR 21783 - Guidance on Media Fills for Validation of Aseptic Preparations for Positron Emission Tomography...

    Science.gov (United States)

    2012-04-11

    ... the same title was announced in the Federal Register on September 30, 2011 (76 FR 60847), and Docket... Preparations for Positron Emission Tomography Drugs; Availability AGENCY: Food and Drug Administration, HHS... guidance entitled ``Media Fills for Validation of Aseptic Preparations for Positron Emission...

  17. 77 FR 71802 - Guidance on Investigational New Drug Applications for Positron Emission Tomography Drugs...

    Science.gov (United States)

    2012-12-04

    ... announced in the Federal Register on February 14, 2012 (77 FR 8262), and Docket No. FDA-2012-D- 0081 was... Positron Emission Tomography Drugs; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice... ``Investigational New Drug Applications for Positron Emission Tomography (PET) Drugs.'' The guidance is intended...

  18. Positron Emission Tomography (PET) and breast cancer in clinical practice

    Energy Technology Data Exchange (ETDEWEB)

    Lavayssiere, Robert [Centre d' Imagerie Paris-Nord, 1, avenue Charles Peguy, 95200 Sarcelles (France); Institut du Sein Henri Hartmann (ISHH), 1, rue des Dames Augustines, 92200 Neuilly sur Seine (France)], E-mail: cab.lav@wanadoo.fr; Cabee, Anne-Elizabeth [Centre d' Imagerie Paris-Nord, 1, avenue Charles Peguy, 95200 Sarcelles (France); Institut du Sein Henri Hartmann (ISHH), 1, rue des Dames Augustines, 92200 Neuilly sur Seine (France); Centre RMX, 80, avenue Felix Faure, 75105 Paris (France); Filmont, Jean-Emmanuel [Institut du Sein Henri Hartmann (ISHH), 1, rue des Dames Augustines, 92200 Neuilly sur Seine (France); American Hospital of Paris, Nuclear Medicine, 63, boulevard Victor Hugo - BP 109, 92202 Neuilly sur Seine Cedex (France)

    2009-01-15

    The landscape of oncologic practice has changed deeply during the past few years and there is now a need, through a multidisciplinary approach, for imaging to provide accurate evaluation of morphology and function and to guide treatment (Image Guided Therapy). Increasing emphasis has been put on Position Emission Tomography (PET) role in various cancers among clinicians and patients despite a general context of healthcare expenditure limitation. Positron Emission Tomography has currently a limited role in breast cancer, but also general radiologists and specialists should be aware of these indications, especially when staging aggressive cancers and looking for recurrence. Currently, the hybrid systems associating PET and Computed Tomography (CT) and in the same device [Rohren EM, Turkington TG, Coleman RE. Clinical applications of PET in oncology. Radiology 2004;231:305-32; Blodgett TM, Meltzer CM, Townsend DW. PET/CT: form and function. Radiology 2007;242:360-85; von Schulthess GK, Steinert HC, Hany TF. Integrated PET/CT: current applications and futures directions. Radiology 2006;238(2):405-22], or PET-CT, are more commonly used and the two techniques are adding their potentialities. Other techniques, MRI in particular, may also compete with PET in some instance and as far as ionizing radiations dose limitation is considered, some breast cancers becoming some form of a chronic disease. Breast cancer is a very complex, non-uniform, disease and molecular imaging at large may contribute to a better knowledge and to new drugs development. Ongoing research, Positron Emission Mammography (PEM) and new tracers, are likely to bring improvements in patient care [Kelloff GJ, Hoffman JM, Johnson B, et al. Progress and promise of FDG-PET Imaging for cancer patient management and oncologic drug development. Clin Cancer Res 2005;1(April (8)): 2005].

  19. Positron Emission Tomography (PET) and breast cancer in clinical practice

    International Nuclear Information System (INIS)

    The landscape of oncologic practice has changed deeply during the past few years and there is now a need, through a multidisciplinary approach, for imaging to provide accurate evaluation of morphology and function and to guide treatment (Image Guided Therapy). Increasing emphasis has been put on Position Emission Tomography (PET) role in various cancers among clinicians and patients despite a general context of healthcare expenditure limitation. Positron Emission Tomography has currently a limited role in breast cancer, but also general radiologists and specialists should be aware of these indications, especially when staging aggressive cancers and looking for recurrence. Currently, the hybrid systems associating PET and Computed Tomography (CT) and in the same device [Rohren EM, Turkington TG, Coleman RE. Clinical applications of PET in oncology. Radiology 2004;231:305-32; Blodgett TM, Meltzer CM, Townsend DW. PET/CT: form and function. Radiology 2007;242:360-85; von Schulthess GK, Steinert HC, Hany TF. Integrated PET/CT: current applications and futures directions. Radiology 2006;238(2):405-22], or PET-CT, are more commonly used and the two techniques are adding their potentialities. Other techniques, MRI in particular, may also compete with PET in some instance and as far as ionizing radiations dose limitation is considered, some breast cancers becoming some form of a chronic disease. Breast cancer is a very complex, non-uniform, disease and molecular imaging at large may contribute to a better knowledge and to new drugs development. Ongoing research, Positron Emission Mammography (PEM) and new tracers, are likely to bring improvements in patient care [Kelloff GJ, Hoffman JM, Johnson B, et al. Progress and promise of FDG-PET Imaging for cancer patient management and oncologic drug development. Clin Cancer Res 2005;1(April (8)): 2005

  20. Clinical impact of 18F-fluorodeoxyglucose positron emission tomography in the diagnosis of neurological diseases

    International Nuclear Information System (INIS)

    In this review it will be discussed in which neurological disorders positron emission tomography can yield important diagnostic information. Because positron emission tomography is an expensive method indications have to be cleary defined. One important question concerns the differentiation of tumor recurrence and scar due to radiation therapy or an operation. The grading of brain tumors is another application. In HIV patients fluorodeoxyglucose positron emission tomography can separate lymphoma and toxoplasmosis. In the evaluation of dementia positron emission tomography can help to clarify the differential diagnosis. Another important area is the presurgical evaluation of epilepsy patients and patients with cerebrovascular disease in whom a surgical revascularization procedure is planned. In extrapyramidal disorders, positron emission tomography can often help to establish the final diagnosis. (author)

  1. Functional images analysis and visualization in positron emission tomography

    International Nuclear Information System (INIS)

    Essentially new information on the metabolism and pathophysiology is available since the recent past using techniques combining the use of positron emitters labelling radiopharmaceuticals, models correctly describing the process studied and system for the in vivo external detection of transverse section of the body. This method is currently called Positron Emission Tomography (PET). At the Service Hospitalier Frederic Joliot of the C.E.A. Departement of Biology, a system was developed for data analysis and colour-coded representation as a tool for functional interpretation. Indeed, the tomographic images, i.e. the radioactive concentration in the transverse section is often but the first step of the study, the actual goal being the regional distribution of a metabolic or physiologic parameter, itself derived from the former distribution by assumption of a model. Such a quantification assumes an accurate analysis of the factors involved in the obtention of the functional image, and the development of the software actually adapted to the clinician's needs. Special attention was given to the representation of graphs and images as a man-machine interface, a tool for model fitting and output of final results in pseudo-color scales adapted to the studied parameter

  2. FDG positron emission computed tomography in a study of aphasia

    International Nuclear Information System (INIS)

    Positron emission computed tomography (PECT) using 18F-2-fluoro-2-deoxy-D-glucose (FDG) was used to investigate the correlations between clinical status, anatomy (as described by CT), and metabolism in five patients with stable aphasia resulting from ischemic cerebral infarction. Local cerebral metabolic activity was diminished in an area larger than the area of infarction demonstrated by CT. In one patient, FDG PECT revealed a metabolic lesion that probably caused the aphasic syndrome and was not apparent by CT. The data suggest that reliance on CT in delineating the extent of the brain lesion in aphasia or other neuropsychological defects can be misleading; FDG PECT may provide important additional information. Two patients with similar metabolic lesions had very different clinical syndromes, showing that even when currently available methods are combined, major gaps remain in clinicoanatomical correlations in aphasia

  3. Studies of the brain cannabinoid system using positron emission tomography

    International Nuclear Information System (INIS)

    Studies using radiolabeled psychoactive drugs in conjunction with positron emission tomography (PET) have permitted the imaging of binding sites in the human brain. Similar studies of marijuana have been hampered by the unsuitability of radiolabeled THC for PET studies, and the current unavailability of other in vivo imaging agents for cannabinoid receptors. Recent developments in medicinal chemistry suggest that a PET radiotracer for cannabinoid receptors will soon become available. This chapter briefly reviews these developments, together with the results of PET studies of the effects of marijuana and other abused drugs on brain metabolism. It also reviews PET studies of cocaine binding sites, to demonstrate the kind of investigations that will be possible when a cannabinoid receptor PET radioligand becomes available

  4. Positron emission tomography with gamma camera in coincidence mode

    International Nuclear Information System (INIS)

    Positron emission tomography using F-18 FDG has been estbalished in clinical diagnostics with first indications especially in oncology. To install a conventional PET tomography (dedicated PET) is financially costly and restricted to PET examinations only. Increasing demand for PET diagnostics on one hand and restricted financial resources in the health system on the other hand led industry to develop SPECT cameras to be operated in coincidence mode (camera PET) in order to offer nuclear medicine physicians cost-effective devices for PET diagnostic. At the same time camera PET is inferior to conventional PET regarding sensitivity and detection-efficiency for 511 keV photons. Does camera-PET offer a reliable alternative to conventional PET? The first larger comparative studies are now available, so a first apraisal about the technical clinical performance of camera-PET can be done. (orig.)

  5. Studies of the brain cannabinoid system using positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Gatley, S.J.; Volkow, N.D.

    1995-10-01

    Studies using radiolabeled psychoactive drugs in conjunction with positron emission tomography (PET) have permitted the imaging of binding sites in the human brain. Similar studies of marijuana have been hampered by the unsuitability of radiolabeled THC for PET studies, and the current unavailability of other in vivo imaging agents for cannabinoid receptors. Recent developments in medicinal chemistry suggest that a PET radiotracer for cannabinoid receptors will soon become available. This chapter briefly reviews these developments, together with the results of PET studies of the effects of marijuana and other abused drugs on brain metabolism. It also reviews PET studies of cocaine binding sites, to demonstrate the kind of investigations that will be possible when a cannabinoid receptor PET radioligand becomes available.

  6. Magnet development for the BRF positron emission tomography accelerator

    International Nuclear Information System (INIS)

    A collaboration involving the Biomedical Research Foundation, Science Applications International Corporation, Fermi National Accelerator Laboratory, and the University of Washington is developing an accelerator for producing isotopes for Positron Emission Tomography (PET) scans. The Medium Energy Beam Transport (MEBT) section of this accelerator takes a small beam from a first RFQ acceleration device and matches it into a small 3D-acceptance at a second RFQ section. The beam transport system was designed to prevent beam losses due to emittance growth. The system includes two bending dipoles and seven quadrupoles of three different types. This report contains a brief description of the MEBT magnets and their electric, magnetic and thermal properties. The magnet measurements show that each of the magnets meets the system requirements

  7. Radiopharmaceuticals for positron emission tomography investigations of Alzheimer's disease

    International Nuclear Information System (INIS)

    Alzheimer's disease (AD) is a common degenerative neurological disease that is an increasing medical, economical, and social problem. There is evidence that a long ''asymptomatic'' phase of the disease exists where functional changes in the brain are present, but structural imaging for instance with magnetic resonance imaging remains normal. Positron emission tomography (PET) is one of the tools by which it is possible to explore changes in cerebral blood flow and metabolism and the functioning of different neurotransmitter systems. More recently, investigation of protein aggregations such as amyloid deposits or neurofibrillary tangles containing tau-protein has become possible. The purpose of this paper is to review the current knowledge on various 18F- and 11C-labelled PET tracers that could be used to study the pathophysiology of AD, to be used in the early or differential diagnosis or to be used in development of treatment and in monitoring of treatment effects. (orig.)

  8. Development of the LBNL positron emission mammography camera

    International Nuclear Information System (INIS)

    We present the construction status of the LBNL Positron Emission Mammography (PEM) camera, which utilizes a PET detector module with depth of interaction measurement consisting of 64 LSO crystals (3x3x30 mm3) coupled on one end to a single photomultiplier tube (PMT) and on the opposite end to a 64 pixel array of silicon photodiodes (PDs). The PMT provides an accurate timing pulse, the PDs identify the crystal of interaction, the sum provides a total energy signal, and the PD/(PD+PMT) ratio determines the depth of interaction. We have completed construction of all 42 PEM detector modules. All data acquisition electronics have been completed, fully tested and loaded onto the gantry. We have demonstrated that all functions of the custom IC work using the production rigid-flex boards and data acquisition system. Preliminary detector module characterization and coincidence data have been taken using the production system, including initial images

  9. Guideline for performance evaluation of positron emission tomographs

    International Nuclear Information System (INIS)

    This supplement presents guideline for performance evaluation of positron emission tomographies (PET). The purpose of this guideline is to define measurement methods for evaluating both the performance of PET equipment and the accuracy of various data corrections in the clinical setting. The guideline has 8 items. The first four items, consisting of spatial dose distributions, scattering fraction, sensitivity, and counting loss and accidental coincidence counting, deals with the basic performance of PET equipment. The next three items, including image uniformity, accuracy of absorption and scattering correction, and characteristics of high counting rate (accuracy of counting loss corrections and S/N ratio), are designed to provide the quantitative evaluation of images reconstructed by various data corrections for absorption, scattering, counting loss, and others. The last item is partial volume effect (recovery coefficient), which is important for the quantitative analysis of PET images, with the aim of both the measurement method of partial volume effect and the definition of phantoms required. (N.K.)

  10. Positron Emission Tomography in the Differential Diagnosis of Parkinsonism

    Directory of Open Access Journals (Sweden)

    Juha O Rinne

    2009-10-01

    Full Text Available Positron emission tomography (PET studies on presynaptic dopaminergic function can reveal hypofunction in early Parkinson’s disease (PD which may help in the early diagnosis especially in patients with mild symptoms. This hypofunction can be detected with fluorodopa (reflecting mainly aromatic amino acid decarboxylase activity of nigrostriatal terminals or dopamine transporter ligands. These studies can also help to distinguish PD from essential tremor. However, investigations of presynaptic dopaminergic function are not useful in the differential diagnosis of parkinsonian syndromes. PET ligands, such as fluorodeoxyglucose (reflecting glucose metabolism and dopamine receptor ligands, reflecting striatal neuronal function are better in this respect. Cardiac sympathetic function studies represent a new and interesting approach to improve differential diagnosis of parkinsonian syndromes but more studies are needed in larger patient populations with longer follow-up to evaluate the usefulness of these investigations. Multitracer approach combining ligands reflecting different aspects of dopaminergic neurotransmission and other physiological function will increase differential diagnostic accuracy.

  11. Differential diagnosis of depression: relevance of positron emission tomography

    International Nuclear Information System (INIS)

    The proper differential diagnosis of depression is important. A large body of research supports the division of depressive illness into bipolar and unipolar subtypes with respect to demographics, genetics, treatment response, and neurochemical mechanisms. Optimal treatment is different for unipolar and bipolar depressions. Treating a patient with bipolar depression as one would a unipolar patient may precipitate a serious manic episode or possibly even permanent rapid cycling disorder. The clinical distinction between these disorders, while sometimes difficult, can often be achieved through an increased diagnostic suspicion concerning a personal or family history of mania. Positron emission tomography and the FDG method, which allow in vivo study of the glucose metabolic rates for discrete cerebral structures, provide new evidence that bipolar and unipolar depression are two different disorders

  12. Positron Emission Tomography: state of the art and future developments

    Science.gov (United States)

    Pizzichemi, M.

    2016-08-01

    Positron emission tomography (PET) plays a fundamental role in medical imaging, with a wide range of applications covering, among the others, oncology, neurology and cardiology. PET has undergone a steady technological evolution since its introduction in mid 20th century, from the development of 3D PET in the late 1980s, to the invention of PET/CT in the 1990s and more recently with the introduction of PET/MR scanners. The current research topics aiming to develop the next generation of PET scanners are summarized in this paper, focusing on the efforts to increase the sensitivity of the detectors, as long as improving their timing, spatial and energy resolutions, with the final goal of reducing the amount of radioactive dose received by the patients and the duration of the exams while improving at the same time the detectability of lesions.

  13. Positron emission tomography in patients with head and neck carcinoma

    International Nuclear Information System (INIS)

    PURPOSE: To examine the role of positron emission tomography (PET) with labeled fluorodeoxyglucose (FDG) in patients with primary neoplasms of the head and neck. MATERIALS and METHODS: Between (9(92)) and (9(94)), forty-four FDG PET scans were performed on 27 patients with head and neck neoplasms. FDG uptake at the tumor sites was quantified with standardized uptake values (SUV). There were seven women and 20 men. Median age was 70 (37 - 85). All patients had squamous cell carcinoma except two with esthesioneuroblastoma. In six patients the primary site was occult and treatment consisted of surgery followed by radiation. In the other patients, primary sites included nasopharynx (2), base of tongue (6), tonsil (4), larynx (2), piriform sinus (3) paranasal sinuses (3) and multiple (1). Three were Stage II, four were Stage III, 11 were Stage IV and three had recurrent disease. Gross disease was treated by radiation (2), twice daily radiation (8) or concurrent chemotherapy and radiation (11). The median follow-up of survivors is 12 months (6 - 30). RESULTS: All patients had baseline scans prior to radiation therapy. In the six patients with occult primaries, no primary lesions were discovered by PET scans. In the other 21 patients, all known primary sites, regional node metastases and distant metastases demonstrated increased uptake on PET imaging. In one patient distant metastases were suggested on PET (but without corroborating clinical or radiographic evidence) and in two patients additional regional node metastases were discovered. Eleven patients had PET scans at the conclusion of radiation therapy. Five patients had complete responses by PET, two had major responses and four had partial responses. However, all these patients had good clinical responses and none have failed locally. Five patients had six scans during follow-up (at 3 to 12 months) to differentiate radiation changes from persistent disease. In four patients the PET scans were negative and they are

  14. Use of transputers in a 3-D positron emission tomograph

    International Nuclear Information System (INIS)

    This paper discusses the use of a VME-based transputer system as a front-end parallel processing engine for Positron Volume Imaging. The authors model different topologies with different numbers of nodes, using the Master/Worker software paradigm called a Processor Farm, and determine optimum configuration parameters for different computation requirements. The versatility and scalability of transputers makes them very suitable for use in PVI tomographs in that the same transputers can be used for speeding up data acquisition, image reconstruction and display

  15. Calculation of Positron Distribution in the Presence of a Uniform Magnetic Field for the Improvement of Positron Emission Tomography (PET) Imaging Using GEANT4 Toolkit

    OpenAIRE

    Mohsen Mashayekhi; Ali Asghar Mowlavi

    2015-01-01

    Introduction Range and diffusion of positron-emitting radiopharmaceuticals are important parameters for image resolution in positron emission tomography (PET). In this study, GEANT4 toolkit was applied to study positron diffusion in soft tissues with and without a magnetic field for six commonly used isotopes in PET imaging including 11C, 13N, 15O, 18F, 68Ga, and 82Rb. Materials and Methods GEANT4 toolkit was used to simulate the transport and interactions of positrons. Calculations ...

  16. The use of positron emission tomography for the evaluation of choline metabolism in the brain of the rhesus monkey

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) offers an unique opportunity to study regional distribution of different compounds noninvasively. After i.v. injection of substances labelled with short-lived isotopes such as C 11, N 13, 0 15, F 18, or Ga 68, the distribution of the radioactive label is measured as a function of ttime by means of a tomographic technique, based on theaannihilation radiation produced during the process of positron emission. Previously, studies on brain choline metabolism have been performed in small animals using tritium or C 14 isotopes. This paper suggests a possible method for the study of brain Ch-metabolism in vivo in primates usin C 11 - labelled Ch

  17. Scintillation crystals for positron emission tomography having a non reflecting band

    International Nuclear Information System (INIS)

    This invention relates generally to positron emission tomography, a sub-field of the class of medical imaging techniques using ionizing radiation and image reconstruction techniques; and more particularly to devices which use an array of scintillation detectors to detect the annihilation radiation from positron disintegration and use this information to reconstruct an image of the distribution of positron emitting isotope within a body section. 6 figs

  18. Spatial registration of echocardiographic and positron emission tomographic heart studies

    International Nuclear Information System (INIS)

    A method has been developed to match corresponding heart regions from functional echocardiographic (Echo) and metabolic fluorine-18-fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography (PET) studies in individual patients. Echo and PET images are spatially correlated by determining homologous anatomical landmarks (the two papillary muscles and the inferior junction of the right ventricle), identifiable in images obtained by both acquisition modalities. Echo-PET image registration is first performed in the plane identified by the three landmarks, using a rigid rotate-translate scale model. The registration parameters are then used to transform the whole PET volume. This allows a consistent Echo-PET regional analysis, according to a segmental subdivision of the heart. The technique was tested on patients. The overlay of Echo and PET registered images proved the reliability of realignment of the three markers and a good spatial correlation of myocardial walls. This approach to image registration could be applied to other acquisition modalities (such as magnetic resonance imaging and single-photon emission tomography), provided that the three anatomical landmarks are visualized. (orig.)

  19. Dynamic Positron Emission Tomography Imaging of Renal Clearable Gold Nanoparticles.

    Science.gov (United States)

    Chen, Feng; Goel, Shreya; Hernandez, Reinier; Graves, Stephen A; Shi, Sixiang; Nickles, Robert J; Cai, Weibo

    2016-05-01

    Optical imaging has been the primary imaging modality for nearly all of the renal clearable nanoparticles since 2007. Due to the tissue depth penetration limitation, providing accurate organ kinetics non-invasively has long been a huge challenge. Although a more quantitative imaging technique has been developed by labeling nanoparticles with single-photon emission computed tomography (SPECT) isotopes, the low temporal resolution of SPECT still limits its potential for visualizing the rapid dynamic process of renal clearable nanoparticles in vivo. The dynamic positron emission tomography (PET) imaging of renal clearable gold (Au) nanoparticles by labeling them with copper-64 ((64) Cu) to form (64) Cu-NOTA-Au-GSH is reported. Systematic nanoparticle synthesis and characterizations are performed to demonstrate the efficient renal clearance of as-prepared nanoparticles. A rapid renal clearance of (64) Cu-NOTA-Au-GSH is observed (>75%ID at 24 h post-injection) with its elimination half-life calculated to be less than 6 min, over 130 times shorter than previously reported similar nanoparticles. Dynamic PET imaging not only addresses the current challenges in accurately and non-invasively acquiring the organ kinetics, but also potentially provides a highly useful tool for studying renal clearance mechanism of other ultra-small nanoparticles, as well as the diagnosis of kidney diseases in the near future. PMID:27062146

  20. Correlated electron-positron emission in heavy-ion collisions

    International Nuclear Information System (INIS)

    A group of narrow electron-positron sum-energy lines with similar mean energies around 610, 750 and 810 keV has been observed with the EPOS spectrometer in both collision systems 238U + 232Th and 238U + 181Ta studied so far at the UNILAC heavy ion accelerator of GSI, Darmstadt. The intensities of the three lines vary with the beam-energy, the variation being most clearly observed for the 748-keV line in 238U + 181Ta. On the basis of our present understanding Internal Pair Conversion in a collision product at rest or in flight as well as coincident lepton emission during the quasiatomic phase of the collision can be excluded as the origin. The very narrow widths of the sum-energy lines as compared to the widths of the associated broad structure in the difference spectrum of the lepton energies seem to argue for a mutual cancellation of kinematical shifts. Such correlation is expected for two leptons emitted back-to-back in a two-body decay of objects being at rest in the heavy-ion c.m. frame. This speculative hypothesis is confronted with the actual dependence of the lines on the individual lepton energy and the lepton emission angle, as well as on the opening angle of the pair. In fact, the back-to-back decay could not be proved to be a general feature of these lines. (orig.)

  1. Geneva University - The AX-PET experiment : A demonstrator for an axial Positron Emission Tomography

    CERN Multimedia

    Université de Genève

    2012-01-01

    Geneva University École de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92   Wednesday 14 March 2012 SEMINAIRE DE PHYSIQUE CORPUSCULAIRE 11.15 a.m. - Science II, Auditoire 1S081, 30, quai Ernest-Ansermet, 1211 Genève 4 The AX-PET experiment : A demonstrator for an axial Positron Emission Tomography Dr Chiara CASELLA   ETH Zurich   PET (Positron Emission Tomography) is a tool for in-vivo functional imaging, successfully used since the earliest days of nuclear medicine. It is based on the detection of the two coincident 511 keV photons from the annihilation of a positron, emitted from a radiotracer injected into the body. Tomographic analysis of the coincidence data allows for a 3D reconstructed image of the source distribution. The AX-PET experiment proposes a novel geometrical approach for a PET scanner, in which l...

  2. Development of radiotracers for imaging NR2B subtype NMDA receptors with positron emission tomography

    International Nuclear Information System (INIS)

    The aim of this thesis was to develop new radioactive tracers for imaging NR2B subtype NMDA receptors with positron emission tomography. Several compounds including 4-(4-fluoro-benzyl)piperidine and presenting interesting in vivo biological properties were the object of a labelling with a positrons emitter atom (11C or 18F)

  3. Imaging optimizations with non-pure and high-energy positron emitters in small animal positron computed tomography; Optimierung der Bildgebung mit nichtreinen und hochenergetischen Positronenstrahlern in der Kleintier-Positronen-Emissions-Tomographie

    Energy Technology Data Exchange (ETDEWEB)

    Harzmann, Sophie

    2014-03-21

    The contribution on imaging optimizations with non-pure and high-energy positron emitters in small animal positron emission tomography (PET) covers the following topics: physical fundamentals of PET, mathematical image reconstruction and data analyses, Monte-Carlo simulations and implemented correction scheme, quantification of cascade gamma coincidences based on simulations and measurements, sinogram based corrections, restoration of the spatial resolution, implementation of full corrections.

  4. Molecular Imaging of Transporters with Positron Emission Tomography

    Science.gov (United States)

    Antoni, Gunnar; Sörensen, Jens; Hall, Håkan

    Positron emission tomography (PET) visualization of brain components in vivo is a rapidly growing field. Molecular imaging with PET is also increasingly used in drug development, especially for the determination of drug receptor interaction for CNS-active drugs. This gives the opportunity to relate clinical efficacy to per cent receptor occupancy of a drug on a certain targeted receptor and to relate drug pharmacokinetics in plasma to interaction with target protein. In the present review we will focus on the study of transporters, such as the monoamine transporters, the P-glycoprotein (Pgp) transporter, the vesicular monoamine transporter type 2, and the glucose transporter using PET radioligands. Neurotransmitter transporters are presynaptically located and in vivo imaging using PET can therefore be used for the determination of the density of afferent neurons. Several promising PET ligands for the noradrenaline transporter (NET) have been labeled and evaluated in vivo including in man, but a really useful PET ligand for NET still remains to be identified. The most promising tracer to date is (S,S)-[18F]FMeNER-D2. The in vivo visualization of the dopamine transporter (DAT) may give clues in the evaluation of conditions related to dopamine, such as Parkinson's disease and drug abuse. The first PET radioligands based on cocaine were not selective, but more recently several selective tracers such as [11C]PE2I have been characterized and shown to be suitable as PET radioligands. Although there are a large number of serotonin transporter inhibitors used today as SSRIs, it was not until very recently, when [11C]McN5652 was synthesized, that this transporter was studied using PET. New candidates as PET radioligands for the SERT have subsequently been developed and [11C]DASB and [11C]MADAM and their analogues are today the most promising ligands. The existing radioligands for Pgp transporters seem to be suitable tools for the study of both peripheral and central drug

  5. A new positron emission particle tracking facility at iThemba LABS

    International Nuclear Information System (INIS)

    Positron emission particle tracking (PEPT) has become a powerful tool for in-situ characterisation of particulate flow within aggressive industrial environments, such as tumbling mills and powder mixers. PEPT is based on the tracking of a single tracer particle which has been labelled with a radionuclide that decays via β decay. The location of the particle is obtained by the triangulation of events associated with the detection of pairs of annihilation γ rays in a modified 'positron camera'. One of the challenges facing PEPT is associated with labelling sub-millimetre sized particles which would allow studies in systems of finer particulate flow, such as flotation cells. The Positron Imaging Centre at the University of Birmingham is currently the only operational PEPT facility in the world. We are presently installing a PEPT laboratory at the iThemba LABS cyclotron facility in Cape Town. Details of this new facility will be presented, together with a flavour of recent PEPT data obtained in Birmingham, and results from our accelerator-based studies at iThemba LABS which are aimed at extending the state-of-the-art in the size and type of labelled tracer particles for PEPT work. (author)

  6. Utilisation of spatial and temporal correlations in positron emission tomography

    International Nuclear Information System (INIS)

    In this thesis we propose, implement, and evaluate algorithms improving spatial resolution in reconstructed images and reducing data noise in positron emission tomography imaging. These algorithms have been developed for a high resolution tomograph (HRRT) and applied to brain imaging, but can be used for other tomographs or studies. We first developed an iterative reconstruction algorithm including a stationary and isotropic model of resolution in image space, experimentally measured. We evaluated the impact of such a model of resolution in Monte-Carlo simulations, physical phantom experiments and in two clinical studies by comparing our algorithm with a reference reconstruction algorithm. This study suggests that biases due to partial volume effects are reduced, in particular in the clinical studies. Better spatial and temporal correlations are also found at the voxel level. However, other methods should be developed to further reduce data noise. We then proposed a maximum a posteriori de-noising algorithm that can be used for dynamic data to de-noise temporally raw data (sino-grams) or reconstructed images. The a priori modeled the coefficients in a wavelet basis of all the signals without noise (in an image or sinogram). We compared this technique with a reference de-noising method on replicated simulations. This illustrates the potential benefits of our approach of sinogram de-noising. (author)

  7. Characterization of time resolved photodetector systems for Positron Emission Tomography

    CERN Document Server

    Powolny, François

    The main topic of this work is the study of detector systems composed of a scintillator, a photodetector and readout electronics, for Positron Emission Tomography (PET). In particular, the timing properties of such detector systems are studied. The first idea is to take advantage of the good timing properties of the NINO chip, which is a fast preamplifier-discriminator developed for the ALICE Time of flight detector at CERN. This chip uses a time over threshold technique that is to be applied for the first time in medical imaging applications. A unique feature of this technique is that it delivers both timing and energy information with a single digital pulse, the time stamp with the rising edge and the energy from the pulse width. This entails substantial simplification of the entire readout architecture of a tomograph. The scintillator chosen in the detector system is LSO. Crystals of 2x2x10mm3 were used. For the photodetector, APDs were first used, and were then replaced by SiPMs to make use of their highe...

  8. Silicon as an unconventional detector in positron emission tomography

    Science.gov (United States)

    Clinthorne, Neal; Brzezinski, Karol; Chesi, Enrico; Cochran, Eric; Grkovski, Milan; Grošičar, Borut; Honscheid, Klaus; Huh, Sam; Kagan, Harris; Lacasta, Carlos; Linhart, Vladimir; Mikuž, Marko; Smith, D. Shane; Stankova, Vera; Studen, Andrej; Weilhammer, Peter; Žontar, Dejan

    2013-01-01

    Positron emission tomography (PET) is a widely used technique in medical imaging and in studying small animal models of human disease. In the conventional approach, the 511 keV annihilation photons emitted from a patient or small animal are detected by a ring of scintillators such as LYSO read out by arrays of photodetectors. Although this has been successful in achieving ˜5 mm FWHM spatial resolution in human studies and ˜1 mm resolution in dedicated small animal instruments, there is interest in significantly improving these figures. Silicon, although its stopping power is modest for 511 keV photons, offers a number of potential advantages over more conventional approaches including the potential for high intrinsic spatial resolution in 3D. To evaluate silicon in a variety of PET "magnifying glass" configurations, an instrument was constructed that consists of an outer partial-ring of PET scintillation detectors into which various arrangements of silicon detectors are inserted to emulate dual-ring or imaging probe geometries. Measurements using the test instrument demonstrated the capability of clearly resolving point sources of 22Na having a 1.5 mm center-to-center spacing as well as the 1.2 mm rods of a 18F-filled resolution phantom. Although many challenges remain, silicon has potential to become the PET detector of choice when spatial resolution is the primary consideration.

  9. The natural history of misery perfusion in positron emission tomography

    International Nuclear Information System (INIS)

    This report reviews the natural courses of misery perfusion in 5 patients with atherosclerotic cerebrovascular occlusion diseases. Cases 1 showed partial improvement and Case 2 showed deterioration of misery perfusion on positron emission tomography (PET). These 2 patients did not show any clinical changes during the follow-up periods. Case 3 showed remarkable improvement of misery perfusion during the 2-year follow-ups, but his neurological condition worsened. The EC-IC bypass improved both in PET and clinical symptoms. Case 4 had a stroke at the region of misery perfusion in PET. Case 5 had a lacunar infarction 2 years after the EC-IC bypass on the opposite side. PET taken one month before the stroke did not show any signs of hypoperfusion in the area of the lacunar infarction. Misery perfusion seems not to be a static but a dynamic condition that can develop into cerebral infarction by some hemodynamic stresses. Cerebral cortical or lobar infarction may occur in the region of severe misery perfusion. EC-IC bypass may prevent impending infarction of the cerebral cortex by improving the regional cerebral blood flow. However, EC-CI bypass will not prevent the lacunar infarction of the basal ganglia or internal capsule. (author)

  10. Clinical application of positron emission tomography imaging in urologic tumors

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is an advanced noninvasive molecular imaging modality that is being investigated for use in the differentiation, diagnosis, and guiding therapy ora variety of cancer types. FDG PET has the unique clinical value in the differentiation, diagnosis, and monitoring therapy of prostate, such as bladder, renal, and testicle cancer. However, high false-positive and false-negative findings are observed in the detection of these tumors with FDG PET. 11C-Choline (CH) and 11C-acetate (AC) can overcome the pitfall of FDG, and appear to be more successful than FGD in imaging prostate cancer and bladder cancer. The short half-life of 11C prevents the widespread use of CH and AC and 18F-fluorocholine (FCH) and 18F-fluoroacetate (FAC) seem to be potential tracers. Potential clinical value of the new PET tracers, such as 3'-deoxy-3'-18F-fluorothymidine (FLT), 18F-fluorodihydrotestosterone (FDHT), and 9-(4-18F-3-hydroxymethylbutyl)-guanine(18F-FHBG) in the detection of urologic tumors, can deserve further study. (authors)

  11. Diagnosis of intrahepatic cholangiocarcinoma with positron emission tomography

    International Nuclear Information System (INIS)

    Diagnosis of intrahepatic cholangiocarcinoma (IC) by positron emission tomography (PET) has been scarcely reported and this paper reviews authors' experience of PET diagnosis of IC with [18F]deoxy-glucose (FDG). Subjects are 20 cases with IC who received FDG-PET diagnosis for evaluating the disease progression and 16 cases with suspicious recurrent IC. PET was done with Advance NXi machine (GE Medical System) 60 min after intravenous 200-250 MBq of FDG. Compared were images by PET and CT. For the IC, diagnostic sensitivities by CT and PET were found to be 95-100% and for metastatic lymph nodes, the sensitivity, specificity and overall accuracy of PET were 38, 100 and 74%, respectively, whereas those of CT, 75, 73 and 74%. For recurrence, those of PET were 77, 67 and 75%. In conclusion, PET images have a compensatory role for CT images, especially for lymphatic metastasis with higher specificity and for recurrence with higher overall accuracy. (R.T.)

  12. Predicting count loss in modern positron-emission tomography systems

    International Nuclear Information System (INIS)

    The purpose of the data-acquisition electronics for any positron-emission tomography (PET) system is to detect and digitally encode annihilation events as they occur. Individual elements of the electronics are placed in parallel or cascade to organize the event information for subsequent processing. Each element is parameterized with a count loss L which is the fraction of events lost due to dead time (encoding delays, etc.) or data overflow in queueing circuits. This is an important parameter because the sensitivity of the tomograph in proportional to (1-L). The authors have categorized processing elements according to five device types. For each type, they find an expression for count loss. Some mathematical models that have appeared in the literature are applicable. These are extended here to include other devices, such as bank encoders and time-to-digital converters (TDC), with coincidence time resolving circuitry. Because some PET systems will have devices that do not fall into these categories, the authors show the derivations of the loss expressions so that one could easily extend their models with parallel derivations for other device types. In addition to PET systems, one should also be able to apply their results to other types of instruments which count random events. Although they concentrate mainly on count loss, they also briefly discuss the evaluation of other metrics of counting efficiency, which are the fraction of miscoded events and the fraction of ''random coincidence'' events

  13. Positron emission tomography in degenerative disorders of the dopaminergic system

    International Nuclear Information System (INIS)

    21 patients who had Parkinson's disease (PD), PD plus dementia of Alzheimer type (PDAT) or progressive supranuclear palsy (PSP), were studied with positron emission tomography (PET) using (18F)-2-fluoro-2-deoxy-D-glucose (FDG). In one patient with strictly unilateral PD side differences in striatal dopa uptake were studied with 6-(18F)fluoro-L-dopa (F-dopa). In patients with PD PET with FDG did not show any significant change in regional cerebral metabolic rates for glucose (rCMR(Glu)). In PDAT glucose metabolism was generally reduced, the most severe decrease was found in parietal cortex. The matebolic pattern was similar to that typically found in patients with Alzheimer's disease (AD). In the patients with strictly unilateral PD rCMR(Glu) was normal, F-dopa PET, however, revealed a distinct reduction of dopa uptake in the contralateral putamen. In PSP glucose metabolism was significantly decreased in subcortical regions (caudatum, putamen and brainstem) and in frontal cortex. Thus PET demonstrated a clear difference of metabolic pattern between PDAT and PSP

  14. Photon time-of-flight-assisted positron emission tomography

    International Nuclear Information System (INIS)

    In positron emission tomography (PET), the annihilation radiation is usually detected as a coincidence occurrence that localizes the position of the annihilation event to a straight line joining the detectors. The measure of the difference between the time of flight (TOF) of the annihilation photons between their inception and their detection permits the localization of the position of the annihilation event along the coincidence line. The incorporation of TOF information into the PET reconstruction process improves the signal-to-noise ratio in the image obtained. The utilization of scintillation detectors utilizing cesium fluoride scintillators, fast photomultiplier tubes, and fast timing circuits allows sub-nanosecond coincidence timing resolution needed for the effective use of TOF in PET. Mathematical considerations and pilot experiments show that with state-of-the-art electronic components and through the application of proper reconstruction algorithms, the combination of TOF and PET positional data improves severalfold the signal-to-noise ratio with respect to conventional PET image reconstruction at the cost of increasing the amount of data to be processed. The construction of a TOF-assisted PET device is within the capability of state-of-the-art technology

  15. Anaesthesia for positron emission tomography scanning of animal brains.

    Science.gov (United States)

    Alstrup, Aage Kristian Olsen; Smith, Donald F

    2013-01-01

    Positron emission tomography (PET) provides a means of studying physiological and pharmacological processes as they occur in the living brain. Mice, rats, dogs, cats, pigs and non-human primates are often used in studies using PET. They are commonly anaesthetized with ketamine, propofol or isoflurane in order to prevent them from moving during the imaging procedure. The use of anaesthesia in PET studies suffers, however, from the drawback of possibly altering central neuromolecular mechanisms. As a result, PET findings obtained in anaesthetized animals may fail to correctly represent normal properties of the awake brain. Here, we review findings of PET studies carried out either in both awake and anaesthetized animals or in animals given at least two different anaesthetics. Such studies provide a means of estimating the extent to which anaesthesia affects the outcome of PET neuroimaging in animals. While no final conclusion can be drawn concerning the 'best' general anaesthetic for PET neuroimaging in laboratory animals, such studies provide findings that can enhance an understanding of neurobiological mechanisms in the living brain. PMID:23349451

  16. Fluorodeoxyglucose positron emission tomography in pancreatic cancer: an unsolved problem

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Takashi [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan); Fukatsu, Hiroshi [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan); Ito, Kengo; Tadokoro, Masanori [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan); Ota, Toyohiro [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan); Ikeda, Mitsuru [Dept. of Medical Information and Medical Records, Nagoya Univ. School of Medicine (Japan); Isomura, Takayuki [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan); Ito, Shigeki [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan); Nishino, Masanari [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan); Ishigaki, Takeo [Dept. of Radiology, Nagoya Univ. School of Medicine (Japan)

    1995-01-01

    The aim of this study was to examine the significance and problems of 2-[fluorine-18]-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in diagnosing pancreatic cancer and mass-forming pancreatitis (MFP). PET, X-ray computed tomography (CT) and magnetic resonance (MR) imaging were performed in 15 patients with pancreatic cancer and nine patients with MFP. The areas of the PET scan were determined according to the markers drawn on the patients at CT or MR imaging. Regions of interests (ROIs) were placed by reference to the CT or MR images corresponding to the PET images. Tissue metabolism was evaluated by the differential absorption ratio (DAR) at 50 min after intravenous injection of FDG [DAR = tissue tracer concentration/(injected dose/body weight)]. The DAR value differed significantly in pancreatic cancer (mean{+-}SD, 4.64{+-}1.94) and MFP (mean{+-}SD, 2.84{+-}2.22) (P<0.05). In one false-negative case (mucinous adenocarcinoma), the tumour contained a small number of malignant cells. In one false-positive case, lymphocytes accumulated densely in the mass in the pancreatic head. Further studies are necessary to investigate the histopathological characteristics (especially the cellularity) and other factors affecting the FDG DAR on PET images. (orig.)

  17. Cerebral perfusion reserve indexes determined by fluoromethane positron emission scanning

    International Nuclear Information System (INIS)

    An index of cerebral perfusion reserve (RES%), defined as the percent change of regional cerebral blood flow over baseline per mm Hg of end-tidal CO2 tension, was determined for each middle cerebral artery (MCA) territory in patients with unilateral carotid distribution transient ischemic attacks or minor cerebrovascular accidents and was compared with that of age-matched, neurologically normal volunteers. Vasodilator responses to induced hypercapnia were tested during inhalation of 5% CO2 in 95% O2 while regional cerebral blood flow was measured by fluoromethane inhalation positron emission tomography. Mean RES% for 24 normal MCA territories was 5.2 +/- 0.8%. Mean RES% for 15 patient nonischemic MCA territories was 3.8 +/- 1.3% and for 15 ischemic MCA territories was 2.8 +/- 1.9% (both p less than 0.001). Individual RES% values and symmetry ratios between ischemic and nonischemic regions were also determined and compared with angiographic data. Areas of diminished, asymmetric, or paradoxical (two patients) CO2 reactivity appear to correspond to areas of compensatory vasodilation. We found this technique to be a safe and reproducible method for defining and recording localized areas of cerebral tissue at apparent risk for hemodynamically related damage

  18. Positron emission tomography in degenerative disorders of the dopaminergic system

    International Nuclear Information System (INIS)

    21 patients who had Parkinson's disease (PD), PD plus dementia of Alzheimer type (PDAT) or progressive supranuclear palsy (PSP), were studied with positron emission tomography (PET) using (18F)-2-fluoro-2-deoxy-D-glucose (FDG). In one patient with strictly unilateral PD side differences in striatal dopa uptake were studied with 6-(18F)fluoro-L-dopa (F-dopa). In patients with PD PET with FDG did not show any significant change in regional cerebral metabolic rates for glucose (rCMR(Glu)). In PDAT glucose metabolism was generally reduced, the most severe decrease was found in parietal cortex. The metabolic pattern was similar to that typically found in patients with Alzheimer's disease (AD). In the patient with strictly unilateral PD rCMR(Glu) was normal, F-dopa PET, however, revealed a distinct reduction of dopa uptake in the contralateral putamen. In PSP glucose metabolism was significantly decreased in subcortical regions (caudatum, putamen and brainstem) and in frontal cortex. Thus PET demonstrated a clear difference of metabolic pattern between PDAT and PSP. (authors)

  19. Measurement of regional cerebral blood flow by positron emission tomography

    International Nuclear Information System (INIS)

    The principal advantage of positron emission tomography over other methods for measuring cerebral blood flow stems from the accurate, quantitative three-dimensional measurements of regional brain radioactivity that are possible with this technique. As a result, accurate quantitative measurements of regional cerebral blood flow can be obtained for both superficial and deep cerebral structures. The value of PET for investigating central nervous system physiology and pathology extends far beyond this, however. Through the use of different radiotracers and appropriate mathematical models, PET can be applied to the measurement of a wide variety of physiologic variables. Measurements of rCBF tell only part of the story. Experience with PET and with a variety of other techniques has taught us that rCBF is at times a poor indicator of the metabolic, functional, and biochemical status of cerebral tissue. It is only by understanding the interaction of all of these factors that our understanding of neurologic disease can advance. It is in the investigation of these complex relationships that the real value of PET resides

  20. 76 FR 47593 - Guidance for Small Business Entities on Current Good Manufacturing Practice for Positron Emission...

    Science.gov (United States)

    2011-08-05

    ... a guidance for small business entities entitled ``PET Drugs--Current Good Manufacturing Practice... entitled ``PET Drugs--Current Good Manufacturing Practice (CGMP); Small Entity Compliance Guide.'' This... Manufacturing Practice for Positron Emission Tomography Drugs; Availability AGENCY: Food and Drug...

  1. Diagnostic value for extrahepatic metastases of hepatocellular carcinoma in positron emission tomography/computed tomography scan

    OpenAIRE

    2012-01-01

    AIM: To evaluated the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan in diagnosis of hepatocellular carcinoma (HCC) and extrahepatic metastases.

  2. Molecular pathology in vulnerable carotid plaques: correlation with [18]-fluorodeoxyglucose positron emission tomography (FDG-PET)

    DEFF Research Database (Denmark)

    Graebe, M; Pedersen, Sune Folke; Borgwardt, L;

    2008-01-01

    OBJECTIVES: Atherosclerosis is recognised as an inflammatory disease, and new diagnostic tools are warranted to evaluate plaque inflammatory activity and risk of cardiovascular events. We investigated [18]-fluorodeoxyglucose (FDG) uptake in vulnerable carotid plaques visualised by positron emission...

  3. Measurement of regional cerebral glucose utilization in man by positron emission tomography

    International Nuclear Information System (INIS)

    The various methods available for the study of regional cerebral glucose consumption in man by positron emission tomography are described and their applications, limitations and principal physiopathological results are presented

  4. Synthesis of the radiopharmaceuticals for positron emission tomography

    International Nuclear Information System (INIS)

    In this paper is shown a short overview of the biogenic positron radiopharmaceuticals production and a brief summary of some PET preparation synthesis. At the end the overview of some forward-looking positron radionuclides, which can be used for a preparation of the PET radiopharmaceuticals is said. A short review of diagnostic use of PET radiopharmaceuticals is presented (authors)

  5. Time stamp generation with inverse FIR filters for Positron Emission Tomography

    International Nuclear Information System (INIS)

    Photon coincidence detection is the process by which Positron Emission Tomography (PET) works. This requires the determination of the time of impact of each coincident photon at the detector system, also known as time stamp. In this work, the timestamp was generated by means of digital time-domain deconvolution with FIR filters for a INa(Tl) based system. The detector deadtime was reduced from 350 ns to 175 ns while preserving the system's energy resolution and a direct relation between the amount of light collected and the temporal resolution was found.(author)

  6. Positron Emission Tomography Imaging of Tumor Angiogenesis with a 66Ga-Labeled Monoclonal Antibody

    OpenAIRE

    Engle, Jonathan W.; Hong, Hao; Zhang, Yin; Valdovinos, Hector F.; Myklejord, Duane V.; Barnhart, Todd E.; Theuer, Charles P.; Robert J. Nickles; Cai, Weibo

    2012-01-01

    The goal of this study was to develop a 66Ga-based positron emission tomography (PET) tracer for non-invasive imaging of CD105 expression during tumor angiogenesis, a hallmark of cancer. 66Ga was produced using a cyclotron with natZn or isotopically enriched 66Zn targets. TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to 2-S-(4-isothiocyanatobenzyl)-1, 4, 7-triazacyclononane-1, 4, 7-triacetic acid (p-SCN-Bn-NOTA) and labeled with 66Ga. No difference in CD105 binding affinit...

  7. Positron Emission Tomography-Scanner at Children`s Hospital of Michigan at Detroit, Michigan

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-31

    The Department of Energy has prepared an environmental assessment (EA), DOE/EA-0795, to support the DOE decision to provide a grant of $7,953,600 to be used in support of a proposed Positron Emission Tomography Scanner at Children`s Hospital of Michigan at Detroit, Michigan. Based upon the analysis in the EA, DOE has determined that the proposed action is not a major Federal action significantly affected the quality of the human environment within the meaning of the National Environmental Policy Act of 1969 (NEPA). Therefore, the preparation of an Environmental Impact Statement is not required and DOE is issuing this Finding of No Significant Impact (FONSI).

  8. Positron Emission Tomography-Scanner at Children's Hospital of Michigan at Detroit, Michigan

    International Nuclear Information System (INIS)

    The Department of Energy has prepared an environmental assessment (EA), DOE/EA-0795, to support the DOE decision to provide a grant of $7,953,600 to be used in support of a proposed Positron Emission Tomography Scanner at Children's Hospital of Michigan at Detroit, Michigan. Based upon the analysis in the EA, DOE has determined that the proposed action is not a major Federal action significantly affected the quality of the human environment within the meaning of the National Environmental Policy Act of 1969 (NEPA). Therefore, the preparation of an Environmental Impact Statement is not required and DOE is issuing this Finding of No Significant Impact (FONSI)

  9. Undulator-based production of polarized positrons

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, G. [Tel-Aviv Univ. (Israel); Barley, J. [Cornell Univ., Ithaca, NY (United States); Batygin, Y. [SLAC, Menlo Park, CA (US)] (and others)

    2009-05-15

    Full exploitation of the physics potential of a future International Linear Collider will require the use of polarized electron and positron beams. Experiment E166 at the Stanford Linear Accelerator Center (SLAC) has demonstrated a scheme in which an electron beam passes through a helical undulator to generate photons (whose first-harmonic spectrum extended to 7.9 MeV) with circular polarization, which are then converted in a thin target to generate longitudinally polarized positrons and electrons. The experiment was carried out with a one-meter-long, 400-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) operated at 46.6 GeV. Measurements of the positron polarization have been performed at five positron energies from 4.5 to 7.5 MeV. In addition, the electron polarization has been determined at 6.7MeV, and the effect of operating the undulator with a ferrofluid was also investigated. To compare the measurements with expectations, detailed simulations were made with an upgraded version of GEANT4 that includes the dominant polarization-dependent interactions of electrons, positrons, and photons with matter. The measurements agree with calculations, corresponding to 80% polarization for positrons near 6 MeV and 90% for electrons near 7 MeV. (orig.)

  10. Undulator-based production of polarized positrons

    International Nuclear Information System (INIS)

    Full exploitation of the physics potential of a future International Linear Collider will require the use of polarized electron and positron beams. Experiment E166 at the Stanford Linear Accelerator Center (SLAC) has demonstrated a scheme in which an electron beam passes through a helical undulator to generate photons (whose first-harmonic spectrum extended to 7.9 MeV) with circular polarization, which are then converted in a thin target to generate longitudinally polarized positrons and electrons. The experiment was carried out with a one-meter-long, 400-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) operated at 46.6 GeV. Measurements of the positron polarization have been performed at five positron energies from 4.5 to 7.5 MeV. In addition, the electron polarization has been determined at 6.7MeV, and the effect of operating the undulator with a ferrofluid was also investigated. To compare the measurements with expectations, detailed simulations were made with an upgraded version of GEANT4 that includes the dominant polarization-dependent interactions of electrons, positrons, and photons with matter. The measurements agree with calculations, corresponding to 80% polarization for positrons near 6 MeV and 90% for electrons near 7 MeV. (orig.)

  11. 18F-fluorodeoxyglucose positron emission tomography in uterine carcinosarcoma

    International Nuclear Information System (INIS)

    Uterine carcinosarcomas clinically confined to the uterus usually harbor occult metastases. We conducted a pilot study to evaluate the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in uterine carcinosarcoma. Patients with histologically confirmed uterine carcinosarcoma were enrolled. Abdominal and pelvic magnetic resonance imaging (MRI)/whole-body computed tomography (CT) scan, and whole-body 18F-FDG PET or PET/CT were undertaken for primary staging, evaluating response, and restaging/post-therapy surveillance. The clinical impact of 18F-FDG PET was determined on a scan basis. A total of 19 patients were recruited and 31 18F-FDG PET scans (including 8 scans performed on a PET/CT scanner) were performed. Positive impacts of scans were found in 36.8% (7/19) for primary staging, 66.7% (2/3) for monitoring response, and 11.1% (1/9) for restaging/post-therapy surveillance. PET excluded falsely inoperable disease defined by MRI in two patients. Aggressive treatment applying to three patients with PET-defined resectable stage IVB disease seemed futile. Two patients died of disease shortly after salvage therapy restaged by PET. With PET monitoring, one stage IVB patient treated by targeted therapy only was alive with good performance. Using PET did not lead to improvement of overall survival of this series compared with the historical control (n = 35) (P 0.779). The preliminary results suggest that 18F-FDG PET is beneficial in excluding falsely inoperable disease for curative therapy and in making a decision on palliation for better quality of life instead of aggressive treatment under the guidance of PET. PET seems to have limited value in post-therapy surveillance or restaging after failure. (orig.)

  12. Silicon as an unconventional detector in positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a widely used technique in medical imaging and in studying small animal models of human disease. In the conventional approach, the 511 keV annihilation photons emitted from a patient or small animal are detected by a ring of scintillators such as LYSO read out by arrays of photodetectors. Although this has been successful in achieving ∼5mm FWHM spatial resolution in human studies and ∼1mm resolution in dedicated small animal instruments, there is interest in significantly improving these figures. Silicon, although its stopping power is modest for 511 keV photons, offers a number of potential advantages over more conventional approaches including the potential for high intrinsic spatial resolution in 3D. To evaluate silicon in a variety of PET “magnifying glass” configurations, an instrument was constructed that consists of an outer partial-ring of PET scintillation detectors into which various arrangements of silicon detectors are inserted to emulate dual-ring or imaging probe geometries. Measurements using the test instrument demonstrated the capability of clearly resolving point sources of 22Na having a 1.5 mm center-to-center spacing as well as the 1.2 mm rods of a 18F-filled resolution phantom. Although many challenges remain, silicon has potential to become the PET detector of choice when spatial resolution is the primary consideration. -- Highlights: ► We examine the use of position-sensitive silicon detectors in magnifying PET geometries. ► A demonstrator using silicon detectors and BGO scintillation detectors was constructed. ► Both single-slice and volume PET configurations were tested. ► For a 4.5 cm field-of-view, resolutions <1mm were achievable. ► Resolution will improve further with higher resolution silicon detectors.

  13. Study of patients with spinocerebellar degeneration using positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Susumu; Tanaka, Makoto; Sun, X.; Sakai, Yasujiro; Hirai, Shunsaku (Gunma Univ., Maebashi (Japan). School of Medicine)

    1993-10-01

    We studied cerebral blood flow, oxygen metabolism and their relation to clinical symptoms in 45 patients with spinocerebellar degeneration (SCD) and 12 normal control subjects using positron emission tomography (PET). Regions of interest were acquired for the cerebellar hemispheres, cerebellar vermis, brainstem, thalami, and cerebral cortices. PET studies revealed that regional cerebral blood flow (CBF), regional cerebral oxygen metabolic rate (CMRO[sub 2]), CBF/mean CBF of each cerebral cortex (CBF/mCBF) and CMRO[sub 2]/mean CMRO[sub 2] of each cerebral cortex (CMRO[sub 2]/mCMRO[sub 2]) in the cerebellar hemispheres, cerebellar vermis, and brainstem showed a significant decrease in comparison with the normal control subjects, while in the cerebral cortices and thalami, SCD patients showed normal values. CBF/mCBF and CMRO[sub 2]/mCMRO[sub 2] were significantly decreased in patients with olivo-pontocerebellar atrophy (OPCA) and Menzel type of hereditary ataxia (Menzel type) in the cerebellar hemispheres, cerebellar vermis, and brainstem, whereas patients with late cortical cerebellar atrophy (LCCA) and Holmes type of hereditary ataxia (Holmes type) revealed a significant decrease of CBF/mCBF and CMRO[sub 2]/mCMRO[sub 2] in the cerebellar hemispheres and cerebellar vermis, but not in the brainstem. Patients with OPCA showed a significant decrease of CBF in the cerebellar hemispheres, cerebellar vermis, brainstem and that of CMRO[sub 2] in the cerebellar hemispheres and cerebellar vermis. Patients with LCCA showed a significant decrease of CBF in the right cerebellar hemisphere and cerebellar vermis. In patients with LCCA and Holmes type, the severity of upper limb ataxia and dysdiadochocinesis were significantly correlated with CBF/mCBF and CMRO[sub 2]/mCMRO[sub 2] in the cerebellar hemispheres and brainstem. PET may be useful for diagnosing SCD and understanding its pathogenesis. (author).

  14. Positron emission tomography in patients with drug-resistant epilepsy

    International Nuclear Information System (INIS)

    Positron emission tomography with 18Fluor-deoxyglucose (18FDG PET) was introduced as method of evaluation of the cerebral metabolism in the early 80s. 18FDG PET/computed tomography (PET/CT) has rapidly become a method of epileptogenic zone localization because of the hypometaboilsm of this zone during the interictal period. This paper represents the first Bulgarian series of patients with drug- resistant epilepsy who were evaluated with 18FDG PET as part of the presurgical work-up. Our study has included 21 patients with drug-resistant epilepsy who were evaluated with 18FDG PET/CT from January 2010 to May 2013. All patients were evaluated with dedicated MRI epilepsy protocol. PET/CT study was fused with 3D MRI study using FSL or GE software. Video EEG monitoring was performed in all 21 patients and seizures were recorded in 18 patients. Hypometabolic zones were found in 15 patients. The hypometabolism was focal in 5 patients, multilobar in 9 patients and hemispheric in 1 patient. The MRI was normal in 8 patients. Hypometabolic zones were found in 3 of these 8 patients with cryptogenic epilepsy. Epilepsy surgery was performed in 6 cases. All operated patients were with hypometabolic zones. Significant seizure reduction after surgery was observed in 5 of 6 operated patients. 18FDG PET/CT is a valuable method for epileptogenic zone localization in patients with drug-resistant epilepsy. The introduction of this method in the bulgarian epilepsy surgery program increases the chances for successful resective surgery. (authors)

  15. Positron Emission Tomography in the Management of Lung Cancer (NSCLC)

    International Nuclear Information System (INIS)

    Lung cancer is the leading cause of cancer deaths in men and the second most common cancer in women. Globally it remains the most commonly diagnosed cancer at 1.35 million, representing 12.4% of all new cancers. Almost half (49.9%) of the lung cancer cases occur in the developing countries of the world, which is a big change since 1980, when it was estimated that 69% were in developed countries. Although lung cancer is the most deadly of all the cancers, it is the only major cancer that does not have a widely accepted screening test. Lung cancer often presents as a solitary pulmonary nodule on chest radiographs, which are usually performed on patients as a preoperative screening test, or as a part of routine health screening, often in the absence of symptoms. Incidental detection can occur in up to 12% of cases in asymptomatic cases. It is clear that there is a need for the accurate diagnosis of these lesions. In recent years Positron early and Emission Tomography (PET) holds early and promise as a noninvasive investigative tool for the evaluation of lung cancer. 18F-FDG PET is currently indicated for the characterization of lung lesions, staging of non-small cell lung carcinoma (NSCLC), detection of distant metastases, and diagnosis of recurrent disease. PET/CT studies are also being increasingly employed in radiotherapy treatment also planning. Furthermore PET also plays an important role in monitoring of treatment response. On the face of it a PET-CT study may appear expensive. But in the overall context, PET/CT is cost-effective in the treatment of Lung cancer. The modality is the best discriminator of disease load if used in the correct clinical setting. It can do away with the need for multiple, many times needless investigations. It can reduce the number of futile operations, unwarranted interventions, as well as over and under treatments of lung cancer. (author)

  16. Positron emission tomography in urological cancer; Positronenemissionstomographie bei urologischen Tumoren

    Energy Technology Data Exchange (ETDEWEB)

    Wit, M. de [Universitaetskrankenhaus Eppendorf, Hamburg (Germany). Abt. Onkologie/Haematologie, Medizinische Klinik; Kotzerke, J. [Universitaetsklinikum Ulm (DE). Radiologie III (Nuklearmedizin)

    2000-09-01

    In staging cancer of the urinary bladder, the kidneys and the prostate and of testicular cancer there is a need for detecting tumor involvement of the lymph nodes to avoid surgical exploration. Positron emission tomography (PET) using fluorodeoxyglucose (FDG) can detect tumorous lymph nodes (sensitivity: 70%, specificity: 85%) which is helpful for several patients. In carcinoma of the prostate, other radiotracers than FDG (e.g. C-11-choline) might be more sensitive to detect tumorous lymph nodes. Up to now no diagnostical benefit of PET in germ cell tumors could be demonstrated in the published small series. In principle FDG-PET is useful in diagnosis of recurrence. In germ cell cancer FDG-PET seems to identify effectively persistent vital tumor tissue after chemotherapy. A multicenter study was initiated to demonstrate the potential of FDG-PET in a sufficient number of patients with germ cell tumor. (orig.) [German] Bei Harnblasen-, Nieren-, Prostata- und Hodenkarzinomen besteht aus klinischer Sicht ein Bedarf an verbessertem Lymphknoten-Staging, um die operative Evaluation zu vermeiden. Die Positronenemissionstomographie (PET) mit Fluordeoxyglukose (FDG) kann daher im Einzelfall bei Harnblasen- und Nierenkarzinomen hilfreich sein (bei Sensitivitaet um 70% und Spezifitaet um 85%). Beim Prostatakarzinom koennten sich andere Radiotracer (z.B. C-11-Cholin) bei der Detektion von tumoroesen Lymphknoten ueberlegen erweisen. Bei Keimzelltumoren konnte ein Nutzen der PET im primaeren Staging bei den bisher publizierten kleinen Studien nicht nachgewiesen werden. Fuer die Rezidivdiagnostik ist bei den genannten Tumoren aus grundsaetzlicher Ueberlegung der Einsatz von DFG-PET sinnvoll. Die Erkennung von vitalem malignen Tumorgewebe nach Chemotherapie erscheint bei Keimzelltumoren mit FDG-PET weitgehend sicher zu gelingen. Eine multizentrische Studie wurde begonnen, die hierueber Aufschluss geben wird. (orig.)

  17. Noninvasive alternatives to arterial blood sampling in positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography is commonly employed for the quantitative assessment of regional biochemistry. The determination of glucose and oxygen utilization rates using [F-18] 2FDG and [0-15] 0/sub 2/ demand accurate measurement of the driving function producing the observed tissue response. Conventional techniques consist of an arterial or venous puncture with either discrete or continuous sampling of blood label concentrations. A time-of-flight (TOF) probe and expired gas detector have been developed as alternatives to these invasive techniques. The acquisition of serial spectra with the TOF pair (4 x 4cm BaF/sub 2/;XP2020Q;380 psec FWHM), sampling a line through the cardiac chambers, reveals the spatial distribution of activity in the heart and surrounding tissue as a function of time. Region-of-interest analysis of the temporally resolved spectra produce the activity time courses required for analysis of tissue response data. Multigated TOF acquisition using a pulsewatch (LED-phototransistor pair which detects finger-tip blood volume changes) as the gating mechanism promises to provide an easy and accurate method for positioning the TOF probe. Dynamic techniques for the measurement of oxygen utilization rates require both the arterial [0-15] 0/sub 2/ and [0-15] H/sub 2/O concentrations. A heated flow-through plastic (NE 102) beta detector was developed to measure the concentration of label in the alveolar gas which was equilibrated with the blood in the pulmonary capillaries. Combining the TOF probe and expired gas data allows the separation of the oxygen and water components of the input function

  18. Analysis of Factors Affecting Positron Emission Mammography (PEM) Image Formation

    International Nuclear Information System (INIS)

    Image reconstruction for positron emission mammography (PEM) with the breast positioned between two parallel, planar detectors is usually performed by backprojection to image planes. Three important factors affecting PEM image reconstruction by backprojection are investigated: (1) image uniformity (flood) corrections, (2) image sampling (pixel size) and (3) count allocation methods. An analytic expression for uniformity correction is developed that incorporates factors for spatial-dependent detector sensitivity and geometric effects from acceptance angle limits on coincidence events. There is good agreement between experimental floods from a PEM system with a pixellated detector and numerical simulations. The analytic uniformity corrections are successfully applied to image reconstruction of compressed breast phantoms and reduce the necessity for flood scans at different image planes. Experimental and simulated compressed breast phantom studies show that lesion contrast is improved when the image pixel size is half of, rather than equal to, the detector pixel size, though this occurs at the expense of some additional image noise. In PEM reconstruction counts usually are allocated to the pixel in the image plane intersected by the line of response (LOR) between the centers of the detection pixels. An alternate count allocation method is investigated that distributes counts to image pixels in proportion to the area of the tube of response (TOR) connecting the detection pixels that they overlay in the image plane. This TOR method eliminates some image artifacts that occur with the LOR method and increases tumor signal-to-noise ratios at the expense of a slight decrease in tumor contrast. Analysis of image uniformity, image sampling and count allocation methods in PEM image reconstruction points to ways of improving image formation. Further work is required to optimize image reconstruction parameters for particular detection or quantitation tasks

  19. Study of brain metabolism using positron emission computed tomography

    International Nuclear Information System (INIS)

    Positron emission tomography permits the three-dimensional regional measurement of metabolism and blood flow in the brain. For the determination of cerebral metabolic rates of glucose by PET 18fluordeoxyglucose is usually applied: cerebral metabolic rate of glucose was found to be 36 to 47 μmol/100 g/min in the grey matter and 23 to 29 μmol/100 g/min in the white matter of normal volunteers. During physiologic activation metabolic rate of glucose is increased in the respective brain areas in relation to the strength and complexity of the stimulation. In patients suffering from ischaemic stroke glucose metabolism is markedly decreased within the infarction. Additonally, glucose metabolism is reduced by 20% in morphologically intact areas of the homolateral cortex, in the basal ganglia, in the cortical area contralateral to the infarction and in the contralateral cerebellum. This remote reduction of glucose utilization is probably caused by functional inactivation of these brain structures; it could be responsible for the diffuse organic syndrome in stroke victims not caused by the focal lesion. In patients suffering from dementia of the multi-infarct type and of the Alzheimer type glucose metabolism is reduced; the lesions in Alzheimer cases are most prominent in partietal and frontal cortical areas. In Chorea Huntington cases glucose metabolism is primarily disturbed in the striate, especially in the caudate nucleus; in these cases the metabolic disturbance can be detected earlier than the atrophy in computed tomograms. Disturbances of glucose and oxygen utilization are not necessary causes, but may also be sequelae od functional impairment. Additional information on pathogentic mechanisms may be obtained by the investigation of the protein synthesis. (orig.)

  20. Effect of tissue heterogeneity on quantification in positron emission tomography

    International Nuclear Information System (INIS)

    As a result of the limited spatial resolution of positron emission tomographic scanners, the measurements of physiological parameters are compromised by tissue heterogeneity. The effect of tissue heterogeneity on a number of parameters was studied by simulation and an analytical method. Five common tracer models were assessed. The input and tissue response functions were assumed to be free from noise and systematic errors. The kinetic model was assumed to be perfect. Two components with different kinetics were mixed in different proportions and contrast with respect to the model parameters. Different experimental protocols were investigated. Of three methods investigated for the measurement of cerebral blood flow (CBF) (steady state, dynamic, integral), the second one was least sensitive to errors caused by tissue heterogeneity and the main effect was an underestimation of the distribution volume. With the steady state method, errors in oxygen extraction fraction caused by tissue heterogeneity were always found to be less than the corresponding errors in CBF. For myocardial blood flow the steady state method was found to perform better than the bolus method. The net accumulation of substrate (i.e. rCMRglc in the case of glucose analogs) was found to be comparatively insensitive to tissue heterogeneity. Individual rate constans such as k2 and k3 for efflux and metabolism of the substrate in the pool of unmetabolized substrate in the tissue, respectively, were found to be more sensitive. In studies of radioligand binding, using only tracer doses, the effect of tissue heterogeneity on the parameter kon.Bmax could be considerable. In studies of radioligand binding using a protocol with two experiments, one with high and one with low specific activity, Bmax was found to be insensitive while Kd was very sensitive to tissue heterogeneity. (orig.)

  1. Effect of tissue heterogeneity on quantification in positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Blomqvist, G. [Dept. of Clinical Neuroscience, Experimental Alcohol and Drug Addiction Research Section, Karolinska Hospital, Stockholm (Sweden); Lammertsma, A.A. [PET Methodology Group, Cyclotron Unit, MRC Clinical Sciences Centre, Royal Postgraduate Medical School, Hammersmith Hospital, London (United Kingdom); Mazoyer, B. [Service Hospitalier Frederic Joliot CEA/Dept. de Biologie, Hopital d`Orsay and Antenne d`Informatique Medicale, Hopital Robert Debre, Paris (France); Wienhard, K. [Max-Planck-Inst. fuer Neurologische Forschung, Koeln (Germany)

    1995-07-01

    As a result of the limited spatial resolution of positron emission tomographic scanners, the measurements of physiological parameters are compromised by tissue heterogeneity. The effect of tissue heterogeneity on a number of parameters was studied by simulation and an analytical method. Five common tracer models were assessed. The input and tissue response functions were assumed to be free from noise and systematic errors. The kinetic model was assumed to be perfect. Two components with different kinetics were mixed in different proportions and contrast with respect to the model parameters. Different experimental protocols were investigated. Of three methods investigated for the measurement of cerebral blood flow (CBF) (steady state, dynamic, integral), the second one was least sensitive to errors caused by tissue heterogeneity and the main effect was an underestimation of the distribution volume. With the steady state method, errors in oxygen extraction fraction caused by tissue heterogeneity were always found to be less than the corresponding errors in CBF. For myocardial blood flow the steady state method was found to perform better than the bolus method. The net accumulation of substrate (i.e. rCMR{sub glc} in the case of glucose analogs) was found to be comparatively insensitive to tissue heterogeneity. Individual rate constans such as k{sub 2} and k{sub 3} for efflux and metabolism of the substrate in the pool of unmetabolized substrate in the tissue, respectively, were found to be more sensitive. In studies of radioligand binding, using only tracer doses, the effect of tissue heterogeneity on the parameter k{sub on}.B{sub max} could be considerable. In studies of radioligand binding using a protocol with two experiments, one with high and one with low specific activity, B{sub max} was found to be insensitive while K{sub d} was very sensitive to tissue heterogeneity. (orig.)

  2. Sensitivity estimation in time-of-flight list-mode positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Herraiz, J. L. [Madrid-MIT M+Visión Consortium, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and Grupo de Física Nuclear, Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Madrid 28040 (Spain); Sitek, A., E-mail: sarkadiu@gmail.com [Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States)

    2015-11-15

    Purpose: An accurate quantification of the images in positron emission tomography (PET) requires knowing the actual sensitivity at each voxel, which represents the probability that a positron emitted in that voxel is finally detected as a coincidence of two gamma rays in a pair of detectors in the PET scanner. This sensitivity depends on the characteristics of the acquisition, as it is affected by the attenuation of the annihilation gamma rays in the body, and possible variations of the sensitivity of the scanner detectors. In this work, the authors propose a new approach to handle time-of-flight (TOF) list-mode PET data, which allows performing either or both, a self-attenuation correction, and self-normalization correction based on emission data only. Methods: The authors derive the theory using a fully Bayesian statistical model of complete data. The authors perform an initial evaluation of algorithms derived from that theory and proposed in this work using numerical 2D list-mode simulations with different TOF resolutions and total number of detected coincidences. Effects of randoms and scatter are not simulated. Results: The authors found that proposed algorithms successfully correct for unknown attenuation and scanner normalization for simulated 2D list-mode TOF-PET data. Conclusions: A new method is presented that can be used for corrections for attenuation and normalization (sensitivity) using TOF list-mode data.

  3. Sensitivity estimation in time-of-flight list-mode positron emission tomography

    International Nuclear Information System (INIS)

    Purpose: An accurate quantification of the images in positron emission tomography (PET) requires knowing the actual sensitivity at each voxel, which represents the probability that a positron emitted in that voxel is finally detected as a coincidence of two gamma rays in a pair of detectors in the PET scanner. This sensitivity depends on the characteristics of the acquisition, as it is affected by the attenuation of the annihilation gamma rays in the body, and possible variations of the sensitivity of the scanner detectors. In this work, the authors propose a new approach to handle time-of-flight (TOF) list-mode PET data, which allows performing either or both, a self-attenuation correction, and self-normalization correction based on emission data only. Methods: The authors derive the theory using a fully Bayesian statistical model of complete data. The authors perform an initial evaluation of algorithms derived from that theory and proposed in this work using numerical 2D list-mode simulations with different TOF resolutions and total number of detected coincidences. Effects of randoms and scatter are not simulated. Results: The authors found that proposed algorithms successfully correct for unknown attenuation and scanner normalization for simulated 2D list-mode TOF-PET data. Conclusions: A new method is presented that can be used for corrections for attenuation and normalization (sensitivity) using TOF list-mode data

  4. Undulator-Based Production of Polarized Positrons

    CERN Document Server

    Alexander, Gideon; Batygin, Yuri; Berridge, Steven; Bharadwaj, Vinod; Bower, Gary; Bugg, William; Decker, Franz-Josef; Dollan, Ralph; Efremenko, Yuri; Floettmann, Klaus; Gharibyan, Vahagn; Hast, Carsten; Iverson, Richard; Kolanoski, Hermann; Kovermann, Jan W; Laihem, Karim; Lohse, Thomas; McDonald, Kirk T; Mikhailichenko, Alexander A; Moortgat-Pick, Gudrid; Pahl, Philipp; Pitthan, Rainer; Poeschl, Roman; Reinherz-Aronis, Erez; Riemann, Sabine; Schaelicke, Andreas; Schueler, Klaus-Peter; Schweizer, Thomas; Scott, Duncan; Sheppard, John C; Stahl, Achim; Szalata, Zenon; Walz, Dieter R; Weidemann, Achim

    2009-01-01

    Full exploitation of the physics potential of a future International Linear Collider will require the use of polarized electron and positron beams. Experiment E166 at the Stanford Linear Accelerator Center (SLAC) has demonstrated a scheme in which an electron beam passes through a helical undulator to generate photons (whose first-harmonic spectrum extended to 7.9MeV) with circular polarization, which are then converted in a thin target to generate longitudinally polarized positrons and electrons. The experiment was carried out with a one-meter-long, 400-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) operated at 46.6GeV. Measurements of the positron polarization have been performed at five positron energies from 4.5 to 7.5MeV. In addition, the electron polarization has been determined at 6.7MeV, and the effect of operating the undulator with a ferrofluid was also investigated. To compare the measurements with expectations, detailed simulations were made with an upgraded version of Geant4...

  5. Catecholaminergic neurotransmission in heart and brain, development of tracers for positron emission tomography

    OpenAIRE

    Langer, Claus Oliver

    2000-01-01

    The catecholamines norepinephrine and its biosynthetic precursor dopamine are two principal neurotransmitters in the human central nervous system (CNS). Moreover, norepinephrine is a major transmitter substance in the peripheral, autonomic nervous system. Positron emission tomography (PET) is a non-invasive imaging technique that uses positron-labeled molecules to image and measure the function of biological processes in vivo. Neuronal catecholaminergic pathways, both in CNS...

  6. In vivo monitoring of tissue function and metabolism using positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) relies on a combination of the use of positron-emitting radioactive tracers and computerized tomography to monitor certain physiological and functional characteristics in vivo and noninvasively. Its special and most powerful applications to date are in brain physiology and neurology. There are many potential research applications in farm animals, such as the mapping of neuro-humoral pathways, but cost and the need for special facilities are likely to be prohibitive

  7. Fabrication of polycrystalline scintillators for the positron emission tomography (PET)

    International Nuclear Information System (INIS)

    Transparent ceramics are becoming more and more important for two new types of applications. On the one hand in cases where high mechanical and thermal demands in combination with optical properties are required, on the other hand where the optical properties of transparent materials like glass are not sufficient e.g. in positron-emission-tomography (PET) diagnostics. Most state of the art PET-scanners are using high-priced single crystals as scintillator material. The technological challenge is to replace single crystal by cost-efficient transparent ceramics. Producing transparent ceramics is ordered in synthesis of the powders and in manufacturing of these into transparent ceramics. The aim of this work was to synthesize single phase yttrium-alumina-and Luthetiumalumina-garnet (YAG, LuAG) powders partially doped with neodymium or praseodymium by four different synthesis routes (Pechini-synthesis, sol-gel-route, coprecipitation and solid state reactions). Additionally industrial LuAG and LuPO4 powders were characterized and manufactured. The powders were processed as submicron- and nanopowders. The compaction of nanopowder greenbodies sintered at high temperatures leads to a ''cross-over'' between both manufacturing route. Newly produced single-phase powders were homogenized with additions of sintering additives like tetraethyl orthosilicate (TEOS) and binders like polyvinyl alcohol (PVA). Moulding the powders were carried out by uniaxial pressing, cold isostatic pressing and in individual cases also by slip casting. The achieved green densities were in a range of 25-42 %. Examination of calcination behaviour leads to a calcination temperature of 1000 C with 2 hours dwell time in air atmosphere. Only solid state reactions resulted into transparent YAG, YAG:Pr, LuAG, LuAG:Pr ceramics. Solid state reactions of nanopowders resulted in heterogeneously transparent samples. Ceramics made by powders of other synthetic routes gave nontransparent ceramics due to porosity

  8. Positron annihilation spectroscopy applied to silicon-based materials

    CERN Document Server

    Taylor, J W

    2000-01-01

    deposition on silicon substrates has been examined. The systematic correlations observed between the nitrogen content of the films and both the fitted Doppler parameters and the positron diffusion lengths are discussed in detail. Profiling measurements of silicon nitride films deposited on silicon substrates and subsequently implanted with silicon ions at a range of fluences were also performed. For higher implantation doses, damage was seen to extend beyond the film layers and into the silicon substrates. Subsequent annealing of two of the samples was seen to have a significant influence on the nature of the films. Positron annihilation spectroscopy, in conjunction with a variable-energy positron beam, has been employed to probe non-destructively the surface and near-surface regions of a selection of technologically important silicon-based samples. By measuring the Doppler broadening of the 511 keV annihilation lineshape, information on the positrons' microenvironment prior to annihilation may be obtained. T...

  9. Laparoscopic Scar: a mimicker of Sister Mary Joseph's nodule on positron emission tomography/CT

    International Nuclear Information System (INIS)

    Positron emission tomography/CT is an established imaging method in the diagnosis and staging of cancers. 18F-fluoro-2-deoxy-D-glucose (FDG) is the most commonly used radiotracer in positron emission tomography/CT. It is a tumour viability agent and usually its uptake within a lesion reflects the presence of a viable tumour tissue. However, false-positive FDG uptake is known to occur in benign processes of either inflammatory or infectious aetiology. We describe FDG uptake at the site of laparoscopic scar that mimicked Sister Mary Joseph's nodule in a patient with gastric adenocarcinoma. Here, the knowledge of the patient's history and subtle imaging findings helped in accurate staging of the patient. In this case report, we emphasize the value of the knowledge of the patient history and awareness of different pitfalls of FDG to achieve a correct diagnosis on positron emission tomography/CT

  10. State of the art and prospects of clinical applications of positron emission tomography and examination with 18F-fluorodeoxyglucose

    International Nuclear Information System (INIS)

    Positron emission tomography attains a 95% precision in oncological diagnosis. The use of fluorine 18-labelled fluorodeoxyglucose during in vivo tumor imaging is based on the finding that neoplasm cells exhibit elevated glycolytic activity. The share of oncological examinations is 70% to 80%, the share of neurological and cardiological examinations is 20% to 30%. The detecting systems make for in vivo resolution at the level of 2 mm. (M.D.)

  11. The 511 keV emission from positron annihilation in the Galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Prantzos, N.; Boehm, C.; Bykov, A. M.; Diehl, R.; Ferriere, K.; Guessoum, N.; Jean, P.; Knoedlseder, J.; Marcowith, A.; Moskalenko, I. V.; Strong, A.; Weidenspointner, G. [CNRS, UMR7095, UMPC and Institut d' Astrophysique de Paris, F-75014, Paris (France) and LAPP, 9 Chemin de Bellevue, BP 110 F-74941 Annecy-le-Vieux (France); A. F. Ioffe Institute of Physics and Technology, Russian Academy of Sciences, 194021, St. Petersburg (Russian Federation); Max Planck Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany); Laboratoire d' Astrophysique de Toulouse-Tarbes, Universite de Toulouse, CNRS, 14 avenue Edouard Belin, F-31400 Toulouse (France); American University of Sharjah, College of Arts and Sciences/Physics Department, P.O. Box 26666, Sharjah (United Arab Emirates); CESR, Universite de Toulouse, CNRS, 9, Avenue du Colonel Roche, Boite Postal 4346, F-31028 Toulouse Cedex 4 (France); L.U.P.M., Universite Montpellier II, CNRS, Place Eugene Bataillon, F-34095 Montpellier (France); Hansen Experimental Physics Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, California 94305 (United States); Max Planck Institut fuer Extraterrestrische Physik, D-85741, Garching (Germany); Max Planck Institut fur Extraterrestrische Physik, Garching, D-85741 Germany, and MPI Halbleiterlabor, Otto-Hahn-Ring 6, D-81739 Muenchen (Germany)

    2011-07-01

    The first {gamma}-ray line originating from outside the Solar System that was ever detected is the 511 keV emission from positron annihilation in the Galaxy. Despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. Observations in the 1990s with OSSE/CGRO (Oriented Scintillation Spectrometer Experiment on GRO satellite/Compton Gamma Ray Observatory) showed that the emission is strongly concentrated toward the Galactic bulge. In the 2000s, the spectrometer SPI aboard the European Space Agency's (ESA) International Gamma Ray Astrophysics Laboratory (INTEGRAL) allowed scientists to measure that emission across the entire Galaxy, revealing that the bulge-to-disk luminosity ratio is larger than observed at any other wavelength. This mapping prompted a number of novel explanations, including rather ''exotic'' ones (e.g., dark matter annihilation). However, conventional astrophysical sources, such as type Ia supernovae, microquasars, or x-ray binaries, are still plausible candidates for a large fraction of the observed total 511 keV emission of the bulge. A closer study of the subject reveals new layers of complexity, since positrons may propagate far away from their production sites, making it difficult to infer the underlying source distribution from the observed map of 511 keV emission. However, in contrast to the rather well-understood propagation of high-energy (>GeV) particles of Galactic cosmic rays, understanding the propagation of low-energy ({approx}MeV) positrons in the turbulent, magnetized interstellar medium still remains a formidable challenge. The spectral and imaging properties of the observed 511 keV emission are reviewed and candidate positron sources and models of positron propagation in the Galaxy are critically discussed.

  12. Positron emission tomography alone, positron emission tomography-computed tomography and computed tomography in diagnosing recurrent cervical carcinoma: a systematic review and meta-analysis

    OpenAIRE

    Xiao, Yi; Wei, Jia; Zhang, Yicheng; Xiong, Weining

    2014-01-01

    Introduction The aim of the study was to assess systematically the accuracies of positron emission tomography (PET), PET/computed tomography (CT), and CT in diagnosing recurrent cervical cancer. Material and methods We searched for articles published from January 1980 to June 2013 using the following inclusion criteria: articles were reported in English; the use of PET, interpreted with or without the use of CT; use of CT to detect recurrent cervical cancer; and histopathologic analysis and/o...

  13. Positron emission tomography and migraine. Tomographie par emission de positons et migraine

    Energy Technology Data Exchange (ETDEWEB)

    Chabriat, H. (CEA, 91 - Orsay (France). Service Hospitalier Frederic Joliot)

    1992-04-01

    Positron emission tomography (PET) is a brain imaging technique that allows in vivo studies of numerous physiological parameters. There have been few PET studies in migraine patients. Cerebral blood flow changes with no variations in brain oxygen consumption have been reported in patients with prolonged neurologic manifestations during migraine attacks. Parenteral administration of reserpine during migraine headache has been followed by a fall in the overall cerebral uptake of glucose. The small sample sizes and a number of methodologic problems complicate the interpretation of these results. Recent technical advances and the development of new PET tracers can be expected to provide further insight into the pathophysiology of migraine. Today cerebral cortex 5 HT{sub 2} serotonin receptors can be studied in migraine patients with PET.

  14. Attenuation correction with Region Growing Method used in the Positron Emission Mammography System

    CERN Document Server

    Gu, Xiao-Yue; Yin, Peng-Fei; Yun, Ming-Kai; Pei, Chai; Fan, Xin; Huang, Xian-Chao; Sun, Xiao-Li; Wei, Long

    2014-01-01

    Positron Emission Mammography imaging system (PEMi) is a nuclear medicine diagnosis method dedicated for breast imaging. It provides a better resolution in detection of millimeter-sized breast tumors than whole-body PET. To address the requirement of semi-quantitative analysis with the radiotracer concentration map of the breast, a new attenuation correction method based on three-dimensional seeded region growing image segmentation (3DSRG-AC) solution was developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuously segmentation property makes this new method free of activity variation of breast tissues. Threshold value chosen is the key point for the segmentation process. The first valley of the grey level histogram of the reconstruction image is set as the lower threshold, which works fine in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution de...

  15. Contribution of 18F-Fluoro-ethyl-tyrosine Positron Emission Tomography to Target Volume Delineation in Stereotactic Radiotherapy of Malignant Cranial Base Tumours: First Clinical Experience

    Directory of Open Access Journals (Sweden)

    Reinhold Graf

    2012-01-01

    Full Text Available Increased amino acid uptake has been demonstrated in intracerebral tumours and head and neck carcinomas of squamous cell origin. We investigated the potential impact of using 18F-fluoro-ethyl-tyrosine (18F-FET-PET/CT in addition to conventional imaging for gross tumour volume (GTV delineation in stereotactic radiotherapy of skull base tumours. The study population consisted of 14 consecutive patients with cranial base tumours (10 with squamous cell histology, 4 others. All patients underwent a FET-PET/CT examination in addition to contrast-enhanced CT and 11 patients underwent MRI. All tumours and histologic types showed increased FET uptake. The GTV was defined by all voxels showing hyperintensity in MRI or CT (GTVMRI/CT or enhancement in PET (GTVPET, forming a GTVcomposite that was used for the initial treatment fields. An additional volume of infiltrative growth outside the GTVMRI/CT of about 1.0 ± 2 cm3 (5% of the conventional volume was demonstrated by FET-PET only (GTVPETplus with significant enlargement (>10% of GTVMRI/CT in three patients. From existing data, we found correlation between cellular density and the standardized uptake value (SUV of FET. We were able to substantially reduce the volume of escalated radiation dose (GTVboost by 11 ± 2 cm3 (24% of the conventional volume.

  16. Pretreatment [18F]-fluoro-2-deoxy-glucose Positron Emission Tomography Maximum Standardized Uptake Value as Predictor of Distant Metastasis in Early-Stage Non-Small Cell Lung Cancer Treated With Definitive Radiation Therapy: Rethinking the Role of Positron Emission Tomography in Personalizing Treatment Based on Risk Status

    International Nuclear Information System (INIS)

    Purpose: The aim of this study was to determine whether the preradiation maximum standardized uptake value (SUVmax) of the primary tumor for [18F]-fluoro-2-deoxy-glucose positron emission tomography (FDG-PET) has a prognostic significance in patients with Stage T1 or T2N0 non-small cell lung cancer (NSCLC) treated with curative radiation therapy, whether conventional or stereotactic body radiation therapy (SBRT). Methods and Materials: Between January 2007 and December 2011, a total of 163 patients (180 tumors) with medically inoperable histologically proven Stage T1 or T2N0 NSCLC and treated with radiation therapy (both conventional and SBRT) were entered in a research ethics board approved database. All patients received pretreatment FDG-PET / computed tomography (CT) at 1 institution with consistent acquisition technique. The medical records and radiologic images of these patients were analyzed. Results: The overall survival at 2 years and 3 years for the whole group was 76% and 67%, respectively. The mean and median SUVmax were 8.1 and 7, respectively. Progression-free survival at 2 years with SUVmax max ≥7 (67% vs 51%; P=.0096). Tumors with SUVmax ≥7 were associated with a worse regional recurrence-free survival and distant metastasis-free survival. In the multivariate analysis, SUVmax ≥7 was an independent prognostic factor for distant metastasis-free survival. Conclusion: In early-stage NSCLC managed with radiation alone, patients with SUVmax ≥7 on FDG-PET / CT scan have poorer outcomes and high risk of progression, possibly because of aggressive biology. There is a potential role for adjuvant therapies for these high-risk patients with intent to improve outcomes

  17. Relationship between the temporal changes in positron-emission-tomography-imaging-based textural features and pathologic response and survival in esophageal cancer patients

    Directory of Open Access Journals (Sweden)

    Stephen ShingFan Yip

    2016-03-01

    Full Text Available Purpose: Although change in SUV measures and PET-based textural features during treatment have shown promise in tumor response prediction, it is unclear which quantitative measure is the most predictive. We compared the relationship between PET-based features and pathologic response and overall survival with the SUV measures in esophageal cancer. Methods: Fifty-four esophageal cancer patients received PET/CT scans before and after chemo-radiotherapy. Of these, 45 patients underwent surgery and were classified into complete, partial, and non-responders to the preoperative chemoradiation. SUVmax and SUVmean, two co-occurrence matrix (Entropy and Homogeneity, two run-length-matrix (High-gray-run-emphasis and Short-run-high-gray-run-emphasis, and two size-zone-matrix (High-gray-zone-emphasis and Short-zone-high-gray-emphasis textures were computed. The relationship between the relative difference of each measure at different treatment time points and the pathologic response and overall survival was assessed using the area under the receiver-operating-characteristic curve (AUC and Kaplan-Meier statistics respectively. Results: All Textures, except Homogeneity, were better related to pathologic response than SUVmax and SUVmean. Entropy was found to significantly distinguish non-responders from the complete (AUC=0.79, p=1.7x10^-4 and partial (AUC=0.71, p=0.01 responders. Non-responders can also be significantly differentiated from partial and complete responders by the change in the run length and size zone matrix textures (AUC=0.71‒0.76, p≤0.02. Homogeneity, SUVmax and SUVmean failed to differentiate between any of the responders (AUC=0.50‒0.57, p≥0.46. However, none of the measures were found to significantly distinguish between complete and partial responders with AUC0.25. Conclusions: For the patients studied, temporal change in Entropy and all Run length matrix were better correlated with pathological response and survival than the SUV

  18. Cerebral metabolic data obtained by positron emission tomography in physiological aging. A review of the literature

    International Nuclear Information System (INIS)

    Following a summary of the general principles and limitations of metabolic measurements by positron emission tomography and of the different indices used to interpret the data, the authors review the results of published studies on physiological aging. Globally, with strict inclusion criteria absolute metabolic values at rest and under partial sensorial deprivation are little or not modified by age. In contrast, functional interactions between regions, as deduced from metabolic intercorrelations, are perhaps different in elderly people. In any case, positron emission tomography seems to discriminate between normal aging and different patterns of pathological aging. Technical improvements, more refined neuropsychological correlations and the use of dynamic activation paradigms will no doubt provide, in the future, a better definition of normal and pathological aging as positron tomography

  19. Cerebral metabolic data obtained by positron emission tomography in physiological aging. A review of the literature

    Energy Technology Data Exchange (ETDEWEB)

    Pellat, J.; Hommel, M.

    1987-06-18

    Following a summary of the general principles and limitations of metabolic measurements by positron emission tomography and of the different indices used to interpret the data, the authors review the results of published studies on physiological aging. Globally, with strict inclusion criteria absolute metabolic values at rest and under partial sensorial deprivation are little or not modified by age. In contrast, functional interactions between regions, as deduced from metabolic intercorrelations, are perhaps different in elderly people. In any case, positron emission tomography seems to discriminate between normal aging and different patterns of pathological aging. Technical improvements, more refined neuropsychological correlations and the use of dynamic activation paradigms will no doubt provide, in the future, a better definition of normal and pathological aging as positron tomography.

  20. Intrinsic spatial resolution limitations due to differences between positron emission position and annihilation detection localization; Limitacoes da resolucao espacial intrinseca devido as diferencas entre a posicao da emissao do positron e a deteccao da localizacao de aniquilacao

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Pedro; Malano, Francisco; Valente, Mauro, E-mail: valente@famaf.unc.edu.ar [Universidad Nacional de Cordoba, Cordoba (Argentina). Fac. de Matematica, Astronomia y Fisica (FaMAF)

    2012-07-01

    Since its successful implementation for clinical diagnostic, positron emission tomography (PET) represents the most promising medical imaging technique. The recent major growth of PET imaging is mainly due to its ability to trace the biologic pathways of different compounds in the patient's body, assuming the patient can be labeled with some PET isotope. Regardless of the type of isotope, the PET imaging method is based on the detection of two 511-keV gamma photons being emitted in opposite directions, with almost 180 deg between them, as a consequence of electron-positron annihilation. Therefore, this imaging method is intrinsically limited by random uncertainties in spatial resolutions, related with differences between the actual position of positron emission and the location of the detected annihilation. This study presents an approach with the Monte Carlo method to analyze the influence of this effect on different isotopes of potential implementation in PET. (author)

  1. 18F-fluorodeoxyglucose positron emission tomography imaging in brain tumours : The Western Australia positron emission tomography/cyclotron service experience

    International Nuclear Information System (INIS)

    Full text: 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) scans in the first 49 patients referred with either possible brain tumour or brain tumour recurrence were reviewed. FDG-PET imaging was reported with reference to anatomical imaging. Based on the report the FDG study was classified as either positive or negative for the presence of tumour. Thirty-eight cases were included in the analysis, 21 having pathological data and 17 with diagnostic clinical follow up. Eleven were excluded, as they had inadequate follow-up data. Of the 21 cases with pathology, 18 were shown to have tumour. In this group there were five false-negative scans and two false-positive PET scans. Seventeen cases were assessed by clinical follow up, nine were considered to have been tumour. There were two false negatives with one false positive. The overall sensitivity, specificity and positive and negative predictive values were 74, 73, 87 and 53% respectively. This is similar to figures previously quoted in published work. Despite relatively limited numbers, the utility of FDG PET imaging in our hands is similar to published reports. With a positive predictive value of 87%, a positive FDG study indicates a high likelihood that there is brain tumour present. A negative study does not exclude the presence of tumour

  2. Should Patient Setup in Lung Cancer Be Based on the Primary Tumor? An Analysis of Tumor Coverage and Normal Tissue Dose Using Repeated Positron Emission Tomography/Computed Tomography Imaging

    International Nuclear Information System (INIS)

    Purpose: Evaluation of the dose distribution for lung cancer patients using a patient setup procedure based on the bony anatomy or the primary tumor. Methods and materials: For 39 patients with non–small-cell lung cancer, the planning fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan was registered to a repeated FDG-PET/CT scan made in the second week of treatment. Two patient setup methods were analyzed based on the bony anatomy or the primary tumor. The original treatment plan was copied to the repeated scan, and target and normal tissue structures were delineated. Dose distributions were analyzed using dose–volume histograms for the primary tumor, lymph nodes, lungs, and spinal cord. Results: One patient showed decreased dose coverage of the primary tumor caused by progressive disease and required replanning to achieve adequate coverage. For the other patients, the minimum dose to the primary tumor did not significantly deviate from the planned dose: −0.2 ± 1.7% (p = 0.71) and −0.1 ± 1.7% (p = 0.85) for the bony anatomy setup and the primary tumor setup, respectively. For patients (n = 31) with nodal involvement, 10% showed a decrease in minimum dose larger than 5% for the bony anatomy setup and 13% for the primary tumor setup. The mean lung dose exceeded the maximum allowed 20 Gy in 21% of the patients for the bony anatomy setup and in 13% for the primary tumor setup, whereas for the spinal cord this occurred in 10% and 13% of the patients, respectively. Conclusions: In 10% and 13% of patients with nodal involvement, setup based on bony anatomy or primary tumor, respectively, led to important dose deviations in nodal target volumes. Overdosage of critical structures occurred in 10–20% of the patients. In cases of progressive disease, repeated imaging revealed underdosage of the primary tumor. Development of practical ways for setup procedures based on repeated high-quality imaging of all tumor sites during

  3. Production And Characterization Of Tungsten-Based Positron Moderators

    International Nuclear Information System (INIS)

    Experiments of interest in Atomic Physics require production of well-defined low-energy positron beams through a moderation process of high-energy positrons, which can be produced by either the use of a radioactive source or by accelerator based pair production process. Tungsten is one of the most commonly used moderator materials because of its reasonable efficiency, high work function and relatively low cost. In this work we present different methods to produce tungsten-based candidate moderators in a variety of shapes. We also present results from characterizing these candidate moderators by ion beam analysis and microscopy techniques.

  4. Positron emission tomography/computerized tomography imaging of multiple focus of neurolymphomatosis

    International Nuclear Information System (INIS)

    Neurolymphomatosis is defined as infiltration of the peripheral nervous system by malignant lymphocytes in the presence of lymphoma. In this case, we described multiple neurol involvement and findings of 18F-fluorodeoxyglucose positron emission tomography/computerized tomography in a 35-year-old female diagnosed with B-cell lymphoma

  5. Recurrent ovarian endodermal sinus tumor: demonstration by computed tomography, magnetic resonance imaging, and positron emission tomography

    International Nuclear Information System (INIS)

    We report a case of recurrent endodermal sinus tumor of the ovary that was identified and/or clearly depicted by computed tomography, magnetic resonance imaging, and positron emission tomography. The potential roles of various imaging modalities in the detection of recurrent endodermal sinus tumor are discussed. (orig.)

  6. Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography in evaluation of residual intramuscular myxoma

    International Nuclear Information System (INIS)

    Intramuscular myxoma (IM) is a rare benign neoplasm. In a patient diagnosed with IM of left thigh, we report the utility of a postoperative fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography scan in assessing the efficacy of surgical excision

  7. Monitoring liver tumor therapy with [18F]FDG positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) with [18F]-2-flurodeoxy-glucose (FDG) can be utilized as a functional imaging modality for monitoring liver tumor therapy. We report three cases in which PET-FDG was more useful for this purpose than other imaging methods and tumor markers

  8. Tomography by positrons emission: integral unit to the service of Mexico

    International Nuclear Information System (INIS)

    The applications of the Positron emission tomography (PET) together with the one radiopharmaceutical 2 - [18 F]-fluoro-2-deoxy-D-glucose in the area of the medical imaging is expanding quickly and it possesses a bigger impact at the moment in favor of those patient to who suffers an oncological, cardiac or neurological illness in Mexico. (Author)

  9. On the possible mixing of the electron capture and the positron emission channels in nuclear decay

    OpenAIRE

    Isakov, V. I.

    2009-01-01

    On the basis of the idea of mixing (interaction) between the electron capture and the positron emission channels in the \\beta^+ decay in the cases when both channels are energetically allowed, we attempt to explain oscillations of the K-capture rates that were possibly seen in the recent experiment.

  10. Positron emission tomography-computed tomography has a clinical impact for patients with cervical cancer

    DEFF Research Database (Denmark)

    Sandvik, Rikke Mulvad; Jensen, Pernille Tine; Hendel, Helle Westergren;

    2011-01-01

    Many studies have found that positron emission tomography-computed tomography (PET-CT) has a high sensitivity and specificity in the identification of metastasis in cervical cancer. Herlev Hospital, Denmark, has been performing PET-CTs in stage I-IV cervical cancer since 1 May 2006. The present...

  11. Small animal positron emission tomography imaging and in vivo studies of atherosclerosis

    DEFF Research Database (Denmark)

    Hag, Anne Mette Fisker; Ripa, Rasmus Sejersten; Pedersen, Sune Folke;

    2013-01-01

    Atherosclerosis is a growing health challenge globally, and despite our knowledge of the disease has increased over the last couple of decades, many unanswered questions remain. As molecular imaging can be used to visualize, characterize and measure biological processes at the molecular and cellu...... knowledge obtained from in vivo positron emission tomography studies of atherosclerosis performed in small animals....

  12. Characterisation of beta(2)-adrenoceptors, using the agonist [C-11]formoterol and positron emission tomography

    NARCIS (Netherlands)

    Visser, T.J; van Waarde, Aaren; Doze, P; Elsinga, P.H; van der Mark, Thomas W.; Kraan, Jan; Ensing, Kees; Vaalburg, W.

    1998-01-01

    The agonist radioligand N-[2-hydroxy-5-[1-hydroxy-2-[[2-(4-[C-11]-methoxyphenyl)-1-methylethyl]amino]ethyl]phenyl]formamide ([C-11]formoterol) was synthesised in order to test its ability to visualise pulmonary beta(2)-adrenoceptors in vivo, with positron emission tomography (PET). Formoterol was la

  13. Capillaries within compartments: microvascular interpretation of dynamic positron emission tomography data

    DEFF Research Database (Denmark)

    Munk, O L; Keiding, S; Bass, L

    2003-01-01

    Measurement of exchange of substances between blood and tissue has been a long-lasting challenge to physiologists, and considerable theoretical and experimental accomplishments were achieved before the development of the positron emission tomography (PET). Today, when modeling data from modern PE...

  14. Diffuse nesidioblastosis diagnosed on a Ga-68 DOTATATE positron emission tomography/computerized tomography.

    Science.gov (United States)

    Arun, Sasikumar; Rai Mittal, Bhagwant; Shukla, Jaya; Bhattacharya, Anish; Kumar, Praveen

    2013-07-01

    The authors describe a 50 days old pre-term infant with persistent hyperinsulinemic hypoglycemia of infancy in whom Ga-68 DOTATATE positron emission tomography/computerized tomography scan showed diffusely increased tracer uptake in the entire pancreas with no abnormal tracer uptake anywhere else in the body, suggestive of a diffuse variant of nesidioblastosis. PMID:24250024

  15. Positron emission imaging device and method of using the same

    Science.gov (United States)

    Bingham, Philip R.; Mullens, James Allen

    2013-01-15

    An imaging system and method of imaging are disclosed. The imaging system can include an external radiation source producing pairs of substantially simultaneous radiation emissions of a picturization emission and a verification emissions at an emission angle. The imaging system can also include a plurality of picturization sensors and at least one verification sensor for detecting the picturization and verification emissions, respectively. The imaging system also includes an object stage is arranged such that a picturization emission can pass through an object supported on said object stage before being detected by one of said plurality of picturization sensors. A coincidence system and a reconstruction system can also be included. The coincidence can receive information from the picturization and verification sensors and determine whether a detected picturization emission is direct radiation or scattered radiation. The reconstruction system can produce a multi-dimensional representation of an object imaged with the imaging system.

  16. The review of myocardial positron emission computed tomography and positron imaging by gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Ohtake, Tohru [Tokyo Univ. (Japan). Faculty of Medicine

    1998-04-01

    To measure myocardial blood flow, Nitrogen-13 ammonia, Oxygen-15 water, Rubidium-82 and et al. are used. Each has merit and demerit. By measuring myocardial coronary flow reserve, the decrease of flow reserve during dipyridamole in patients with hypercholesterolemia or diabetes mellitus without significant coronary stenosis was observed. The possibility of early detection of atherosclerosis was showed. As to myocardial metabolism, glucose metabolism is measured by Fluorine-18 fluorodeoxyglucose (FDG), and it is considered as useful for the evaluation of myocardial viability. We are using FDG to evaluate insulin resistance during insulin clamp in patients with diabetes mellitus by measuring glucose utilization rate of myocardium and skeletal muscle. FFA metabolism has been measured by {sup 11}C-palmitate, but absolute quantification has not been performed. Recently the method for absolute quantification was reported, and new radiopharmaceutical {sup 18}F-FTHA was reported. Oxygen metabolism has been estimated by {sup 11}C-acetate. Myocardial viability, cardiac efficiency was evaluated by oxygen metabolism. As to receptor or sympathetic nerve end, cardiac insufficiency or cardiac transplantation was evaluated. Imaging of positron emitting radiopharmaceutical by gamma camera has been performed. Collimator method is clinically useful for cardiac imaging of viability study. (author). 54 refs.

  17. The review of myocardial positron emission computed tomography and positron imaging by gamma camera

    International Nuclear Information System (INIS)

    To measure myocardial blood flow, Nitrogen-13 ammonia, Oxygen-15 water, Rubidium-82 and et al. are used. Each has merit and demerit. By measuring myocardial coronary flow reserve, the decrease of flow reserve during dipyridamole in patients with hypercholesterolemia or diabetes mellitus without significant coronary stenosis was observed. The possibility of early detection of atherosclerosis was showed. As to myocardial metabolism, glucose metabolism is measured by Fluorine-18 fluorodeoxyglucose (FDG), and it is considered as useful for the evaluation of myocardial viability. We are using FDG to evaluate insulin resistance during insulin clamp in patients with diabetes mellitus by measuring glucose utilization rate of myocardium and skeletal muscle. FFA metabolism has been measured by 11C-palmitate, but absolute quantification has not been performed. Recently the method for absolute quantification was reported, and new radiopharmaceutical 18F-FTHA was reported. Oxygen metabolism has been estimated by 11C-acetate. Myocardial viability, cardiac efficiency was evaluated by oxygen metabolism. As to receptor or sympathetic nerve end, cardiac insufficiency or cardiac transplantation was evaluated. Imaging of positron emitting radiopharmaceutical by gamma camera has been performed. Collimator method is clinically useful for cardiac imaging of viability study. (author). 54 refs

  18. Evaluation of contrast reproduction method based on the anatomical guidance of the cerebral images reconstruction in positron emission tomography; Evaluation d'une methode de restitution de contraste basee sur le guidage anatomique de la reconstruction des images cerebrales en tomographie par emission de positons

    Energy Technology Data Exchange (ETDEWEB)

    Bataille, F

    2007-04-15

    Positron emission tomography is a medical imaging modality providing in-vivo volumetric images of functional processes of the human body, which is used for the diagnosis and the following of neuro degenerative diseases. PET efficiency is however limited by its poor spatial resolution, which generates a decrease of the image local contrast and leads to an under-estimation of small cerebral structures involved in the degenerative mechanism of those diseases. This so-called partial volume effect degradation is usually corrected in a post-reconstruction processing framework through the use of anatomical information, whose spatial resolution allows a better discrimination between functional tissues. However, this kind of method has the major drawback of being very sensitive to the residual mismatches on the anatomical information processing. We developed in this thesis an alternative methodology to compensate for the degradation, by incorporating in the reconstruction process both a model of the system impulse response and an anatomically-based image prior constraint. This methodology was validated by comparison with a post-reconstruction correction strategy, using data from an anthropomorphic phantom acquisition and then we evaluated its robustness to the residual mismatches through a realistic Monte Carlo simulation corresponding to a cerebral exam. The proposed algorithm was finally applied to clinical data reconstruction. (author)

  19. 18F-Labeled Silicon-Based Fluoride Acceptors: Potential Opportunities for Novel Positron Emitting Radiopharmaceuticals

    OpenAIRE

    Vadim Bernard-Gauthier; Carmen Wängler; Esther Schirrmacher; Alexey Kostikov; Klaus Jurkschat; Bjoern Wängler; Ralf Schirrmacher

    2014-01-01

    Background. Over the recent years, radiopharmaceutical chemistry has experienced a wide variety of innovative pushes towards finding both novel and unconventional radiochemical methods to introduce fluorine-18 into radiotracers for positron emission tomography (PET). These “nonclassical” labeling methodologies based on silicon-, boron-, and aluminium-18F chemistry deviate from commonplace bonding of an [18F]fluorine atom (18F) to either an aliphatic or aromatic carbon atom. One method in part...

  20. Three-dimensional imaging of hidden objects using positron emission backscatter

    International Nuclear Information System (INIS)

    Positron emission backscatter imaging is a technique for interrogation and three-dimensional (3-D) reconstruction of hidden objects when we only have access to the objects from one side. Using time-of-flight differences in detected direct and backscattered positron-emitted photons, we construct 3-D images of target objects. Recently at Los Alamos National Laboratory, a fully three-dimensional imaging system has been built and the experimental results are discussed in this paper. Quantitative analysis of images reconstructed in both two- and three-dimensions are also presented.

  1. Graphics processing unit (GPU)-accelerated particle filter framework for positron emission tomography image reconstruction.

    Science.gov (United States)

    Yu, Fengchao; Liu, Huafeng; Hu, Zhenghui; Shi, Pengcheng

    2012-04-01

    As a consequence of the random nature of photon emissions and detections, the data collected by a positron emission tomography (PET) imaging system can be shown to be Poisson distributed. Meanwhile, there have been considerable efforts within the tracer kinetic modeling communities aimed at establishing the relationship between the PET data and physiological parameters that affect the uptake and metabolism of the tracer. Both statistical and physiological models are important to PET reconstruction. The majority of previous efforts are based on simplified, nonphysical mathematical expression, such as Poisson modeling of the measured data, which is, on the whole, completed without consideration of the underlying physiology. In this paper, we proposed a graphics processing unit (GPU)-accelerated reconstruction strategy that can take both statistical model and physiological model into consideration with the aid of state-space evolution equations. The proposed strategy formulates the organ activity distribution through tracer kinetics models and the photon-counting measurements through observation equations, thus making it possible to unify these two constraints into a general framework. In order to accelerate reconstruction, GPU-based parallel computing is introduced. Experiments of Zubal-thorax-phantom data, Monte Carlo simulated phantom data, and real phantom data show the power of the method. Furthermore, thanks to the computing power of the GPU, the reconstruction time is practical for clinical application. PMID:22472843

  2. Simulation study of respiratory-induced errors in cardiac positron emission tomography/computed tomography

    International Nuclear Information System (INIS)

    Heart disease is a leading killer in Canada and positron emission tomography (PET) provides clinicians with in vivo metabolic information for diagnosing heart disease. Transmission data are usually acquired with 68Ge, although the advent of PET/CT scanners has made computed tomography (CT) an alternative option. The fast data acquisition of CT compared to PET may cause potential misregistration problems, leading to inaccurate attenuation correction (AC). Using Monte Carlo simulations and an anthropomorphic dynamic computer phantom, this study determines the magnitude and location of respiratory-induced errors in radioactivity uptake measured in cardiac PET/CT. A homogeneous tracer distribution in the heart was considered. The AC was based on (1) a time-averaged attenuation map (2) CT maps from a single phase of the respiratory cycle, and (3) CT maps phase matched to the emission data. Circumferential profiles of the heart uptake were compared and differences of up to 24% were found between the single-phase CT-AC method and the true phantom values. Simulation results were supported by a PET/CT canine study which showed differences of up to 10% in the heart uptake in the lung-heart boundary region when comparing 68Ge- to CT-based AC with the CT map acquired at end inhalation

  3. Determination of the positron diffusion length in Kapton by analysing the positronium emission

    International Nuclear Information System (INIS)

    Doppler profile spectroscopy and Compton-to-peak ratio analysis have been used to study the positronium (Ps) emission from the Kapton surface as a function of the positron implantation energy E. Two different positions for the sample have been performed in the experiment. In the first case the sample and the Ge-detector are perpendicular to the positron beam. With this geometry the emission of para-positronium (p-Ps) is detected as a narrow central peak. In the second case, by rotating the sample 45 deg. with respect to the beam axis, the emission of p-Ps is detected as a blue-shifted fly away peak. The implantation of the positrons is described by the Makhov profile, where we used the modified median implantation for polymers as given by Algers et al. [J. Algers, P. Sperr, W. Egger, G. Koegel, F.H.J. Maurer, Phys. Rev. B 67 (2003) 125404]. Thermalised positrons can diffuse to the surface and may pick up an electron to be emitted as Ps. We found a thermal and or epithermal positron diffusion length L+ = 5.43 ± 0.71 nm and L+ = 5.51 ± 0.28 nm correspondingly for both cases, which is much more than the one found by Brusa et al. [R.S. Brusa, A. Dupasquier, E. Galvanetto, A. Zecca, Appl. Phys. A 54 (1992) 233]. The respective efficiency for the emission of Ps by picking up an electron from the surface is found to be fpu = 0.247 ± 0.012 and fpu = 0.156 ± 0.003

  4. A new method of detection for a positron emission tomograph using a time of flight method

    International Nuclear Information System (INIS)

    In the first chapter, it is shown the advantages of positron radioemitters (β+) of low period, and the essential characteristics of positron tomographs realized at the present time. The second chapter presents the interest of an original technique of image reconstruction: the time of flight technique. The third chapter describes the characterization methods which were set for verifying the feasibility of cesium fluoride in tomography. Chapter four presents the results obtained by these methods. It appears that the cesium fluoride constitute presently the best positron emission associated to time of flight technique. The hypotheses made on eventual performances of such machines are validated by experiments with phantom. The results obtained with a detector (bismuth germanate) conserves all its interest in skull tomography

  5. Positron emission tomography studies of central receptors in humans

    International Nuclear Information System (INIS)

    Central neurotransmitter systems and receptors are intimately involved in the mechanism of several neurologic and psychiatric disorders. One well-known example is the nigro-striatal dopaminergic system in akinesia of Parkinson's disease. Although neurotransmitter concentration and receptor function can be measured regionally post-mortem, positron tomography (PET) studies can be performed during life and therefore may provide insight into changes at early stages of the disease as well as follow-up data on, and pharmacological modification of, such changes. 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. This principle was first pioneered using 3H or 14C-labeled ligands injected intravenously to laboratory animal, but necessitated brain tissue sampling for determination of regional radioactive concentration. The feasibility of the PET paradigm to characterize specific binding in vivo showed that trace amounts of 11C-labeled flunitrazepam could be displaced specifically from the baboon's brain by a therapeutic load of the unlabeled competitor Lorazepam, indicating that specific in vivo binding of the radioligand to the benzodiazepine (BZD) receptors has taken place

  6. Evaluation of various attenuation correction methods for brain imaging in positron emission tomography

    International Nuclear Information System (INIS)

    Corrections for photon attenuation in positron emission tomography (PET) will, in general, affect quantitative accuracy and noise characteristics of the reconstructed images. Each correction approach provides certain advantages as well as disadvantages. The choice of the best method for a particular study depends on the task objective, e.g., lesion detection or quantitation, and limits of acquisition and processing time. In the present study, the following attenuation correction methods have been systematically evaluated for brain imaging with PET: (1) analytical model method; (2) direct transmission measurement method; (3) smoothed transmission data method; (4) reconstructed transmission image method; (5) object contour method; and (6) boundary method. Criteria for evaluating the performance of these methods have been developed in terms of computation efficiency and image quality descriptors such as quantitative accuracy, reconstructed image resolution, and noise characteristics. Effects of total number of transmission counts, total number of emission counts, size of the region of interest, smoothing parameters, reconstruction filters, and object contrast have also been investigated. Based on the results of computer simulation studies, the establishment of a methodology for choosing the best attenuation correction method for a defined purpose, e.g., detecting a 2 cm diameter lesion or quantitating a 4 cm diameter region, has been attempted. This systematic approach has been applied to phantom and in vivo studies. In most cases, the smoothed transmission data method appears to be the best compromise of computation time and image quality

  7. Optimised motion tracking for positron emission tomography studies of brain function in awake rats.

    Directory of Open Access Journals (Sweden)

    Andre Z Kyme

    Full Text Available Positron emission tomography (PET is a non-invasive molecular imaging technique using positron-emitting radioisotopes to study functional processes within the body. High resolution PET scanners designed for imaging rodents and non-human primates are now commonplace in preclinical research. Brain imaging in this context, with motion compensation, can potentially enhance the usefulness of PET by avoiding confounds due to anaesthetic drugs and enabling freely moving animals to be imaged during normal and evoked behaviours. Due to the frequent and rapid motion exhibited by alert, awake animals, optimal motion correction requires frequently sampled pose information and precise synchronisation of these data with events in the PET coincidence data stream. Motion measurements should also be as accurate as possible to avoid degrading the excellent spatial resolution provided by state-of-the-art scanners. Here we describe and validate methods for optimised motion tracking suited to the correction of motion in awake rats. A hardware based synchronisation approach is used to achieve temporal alignment of tracker and scanner data to within 10 ms. We explored the impact of motion tracker synchronisation error, pose sampling rate, rate of motion, and marker size on motion correction accuracy. With accurate synchronisation (20 Hz, and a small head marker suitable for awake animal studies, excellent motion correction results were obtained in phantom studies with a variety of continuous motion patterns, including realistic rat motion (<5% bias in mean concentration. Feasibility of the approach was also demonstrated in an awake rat study. We conclude that motion tracking parameters needed for effective motion correction in preclinical brain imaging of awake rats are achievable in the laboratory setting. This could broaden the scope of animal experiments currently possible with PET.

  8. Basal ganglia disorders studied by positron emission tomography

    International Nuclear Information System (INIS)

    Recent development of positron emitting radioligands has made it possible to investigate the alterations of neurotransmitter systems associated with basal ganglia disorders in vivo. The functional integrity of nigro-striatal dopaminergic terminals may be studied with [18F]6-fluoro-L-dopa ([18F]dopa), and striatal dopamine receptor density with suitable PET ligands. [18F]dopa uptake in the striatum (putamen) is markedly reduced in patients with Parkinson's disease (PD). [18F]dopa-PET is capable of detecting sub-clinical nigral dysfunction in asymptomatic patients with familial PD and those who become Parkinsonian on conventional doses of dopamine receptor antagonists. While putamen [18F]dopa uptake is reduced to a similar level in patients with multiple system atrophy (MSA) and PD, caudate [18F] dopa uptake is lower in MSA than PD. However, [18F]dopa PET cannot consistently distinguish MSA from PD because individual ranges of caudate [18F]dopa uptake overlap. D1 and D2 receptor binding is markedly reduced in the striatum (posterior putamen) of MSA patients. Therefore, dopamine receptor imaging is useful for the differential diagnosis of MSA and PD. Similar marked reductions in putamen and caudate [18F]dopa uptake have been observed in patients with progressive supranuclear palsy (PSP). Moderate reductions in D2 receptor binding have been reported in the striatum of PSP patients. The reduction in D2 receptor binding is more prominent in the caudate than putamen. Striatal [18F]dopa uptake is normal or only mildly reduced in patients with dopa responsive dystonia (DRD). D2 receptor binding is markedly reduced in patients with Huntington's disease, while striatal [18F]dopa uptake is normal or mildly reduced. In summary, PET can demonstrate characteristic patterns of disruption of dopaminergic systems associated with basal ganglia disorders. These PET findings are useful in the differential diagnosis of basal ganglia disorders. (J.P.N.) 55 refs

  9. Persistence of cerebral metabolic abnormalities in chronic schizophrenia as determined by positron emission tomography

    International Nuclear Information System (INIS)

    Local cerebral metabolic rates were determined by positron emission tomography and the deoxyglucose method in a group of 10 chronic schizophrenic subjects before and after somatic treatment and in eight normal subjects. Before treatment, schizophrenic subjects had markedly lower absolute metabolic activity than did normal controls in both frontal and temporal regions and a trend toward relative hyperactivity in the basal ganglia area. After treatment, their metabolic rates approached those seen in normal subjects in nearly all regions except frontal. Persistence of diminished frontal metabolism was manifested as significant relative hypofrontality. These findings suggest specific loci of aberrant cerebral functioning in chronic schizophrenia and the utility of positron emission tomography in characterizing these abnormalities

  10. Scar or recurrent rectal cancer. Positron emission tomography is more helpful for diagnosis than immunoscintigraphy

    International Nuclear Information System (INIS)

    We used positron emission tomography and fludeoxyglucose F-18 to assess metabolic activity of a pelvic mass in 18 patients who had suspected recurrent rectal cancer. Computed tomography could not differentiate tumor from scar. All patients presenting increased uptake of fludeoxyglucose F 18 by the mass were proved by histologic studies to suffer from recurrent tumor. Six of seven patients with low fludeoxyglucose uptake had nonmalignant lesions. Using immunoscintigraphy in 14 patients with elevated carcinoembryonic antigen levels, only four of ten recurrences could be identified by increased antibody accumulation in the mass. On the other hand, two of four benign lesions were interpreted as being recurrent tumor because of high uptake. Therefore, only positron emission tomography seems to be a useful diagnostic tool in the differentiation of recurrent rectal cancer and scar by providing information about the metabolic activity of a mass

  11. Brain metabolism in autism. Resting cerebral glucose utilization rates as measured with positron emission tomography

    International Nuclear Information System (INIS)

    The cerebral metabolic rate for glucose was studied in ten men (mean age = 26 years) with well-documented histories of infantile autism and in 15 age-matched normal male controls using positron emission tomography and (F-18) 2-fluoro-2-deoxy-D-glucose. Positron emission tomography was completed during rest, with reduced visual and auditory stimulation. While the autistic group as a whole showed significantly elevated glucose utilization in widespread regions of the brain, there was considerable overlap between the two groups. No brain region showed a reduced metabolic rate in the autistic group. Significantly more autistic, as compared with control, subjects showed extreme relative metabolic rates (ratios of regional metabolic rates to whole brain rates and asymmetries) in one or more brain regions

  12. Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography

    Science.gov (United States)

    Christensen, A. N.; Rydhög, J. S.; Søndergaard, R. V.; Andresen, T. L.; Holm, S.; Munck Af Rosenschöld, P.; Conradsen, K.; Jølck, R. I.

    2016-05-01

    Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive 106Ag, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy (10- and 22 Gy) in a high-energy beam setting (18 MV). The developed silver-nanosensor provided high radiopacity on the planning CT-scans sufficient for patient positioning in image-guided radiotherapy and provided dosimetric information about the absorbed dose with a 10% and 8% standard deviation for the stereotactic regimens, 10 and 22 Gy, respectively.Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive 106Ag, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The

  13. An 8×8 Row-Column Summing Readout Electronics for Preclinical Positron Emission Tomography Scanners

    OpenAIRE

    Shih, Y. C.; Sun, F. W.; MacDonald, L R; Otis, B. P.; Miyaoka, R S; McDougald, W.; Lewellen, T K

    2009-01-01

    This work presents a row/column summing readout electronics for an 8×8 silicon photomultiplier array. The summation circuit greatly reduces the number of electronic channels, which is desirable for pursuing higher resolution positron emission tomography scanners. By using a degenerated common source topology in the summation circuit, more fan-in is possible and therefore a greater reduction in the number of electronic channels can be achieved. The timing signal is retrieved from a common anod...

  14. Dynamic Positron Emission Tomography Image Restoration via a Kinetics-Induced Bilateral Filter

    OpenAIRE

    Bian, Zhaoying; Huang, Jing; Ma, Jianhua; Lu, Lijun; Niu, Shanzhou; Zeng, Dong; Feng, Qianjin; Chen, Wufan

    2014-01-01

    Dynamic positron emission tomography (PET) imaging is a powerful tool that provides useful quantitative information on physiological and biochemical processes. However, low signal-to-noise ratio in short dynamic frames makes accurate kinetic parameter estimation from noisy voxel-wise time activity curves (TAC) a challenging task. To address this problem, several spatial filters have been investigated to reduce the noise of each frame with noticeable gains. These filters include the Gaussian f...

  15. Noninvasive measurement of regional myocardial glucose metabolism by positron emission computed tomography. [Dogs

    Energy Technology Data Exchange (ETDEWEB)

    Schelbert, H.R.; Phelps, M.E.

    1980-06-01

    While the results of regional myocardial glucose metabolism measurements using positron emission computed tomography (/sup 13/N-ammonia) are promising, their utility and value remains to be determined in man. If this technique can be applied to patients with acute myocardial ischemia or infarction it may permit delineation of regional myocardial segments with altered, yet still active metabolism. Further, it may become possible to evaluate the effects of interventions designed to salvage reversibly injured myocardium by this technique.

  16. Value of positron emission tomography in diagnosing synchronous penile metastasis from urothelial bladder cancer

    OpenAIRE

    Rouanne, M.; Alhammadi, A.; Vilain, D.; Radulescu, C.; Lebret, T.

    2015-01-01

    Metastases to the penis are extremely rare events. Most frequently, penile metastases come from the urogenital system (bladder, prostate) or the rectum-sigmoid colon. Usually painful, penile lesions may be asymptomatic, making diagnosis more challenging. Hence, we report the adding value of 18F-fludeoxyglucose–positron emission tomography/computed tomography (18F-FDG PET/CT) in the detection of penile metastases originating from urothelial carcinoma of the bladder. Arguably, penile metastases...

  17. Positron emission tomography radioligands for in vivo imaging of Aβ plaques

    OpenAIRE

    Mason, N Scott; Mathis, Chester A.; Klunk, William E

    2013-01-01

    The development of positron emission tomography (PET) radioligands for the non-invasive imaging of amyloid-β plaque burden has been the focus of intense research efforts over the last decade. A variety of structural backbones have been investigated and several radiolabeled molecules have been evaluated in phase I (and later) clinical studies. These efforts have been driven by the desire not only to develop a suitable diagnostic imaging agent but also to develop a means to evaluate potential t...

  18. [(18)F]Fluoroethyltyrosine- positron emission tomography-guided radiotherapy for high-grade glioma

    OpenAIRE

    Ratib Osman; Dipasquale Giovanna; Nouet Philippe; Rouzaud Michel; Haller Guy; Casanova Nathalie; Buchegger Franz; Zilli Thomas; Weber Damien C; Zaidi Habib; Vees Hansjorg; Miralbell Raymond

    2008-01-01

    Abstract Background To compare morphological gross tumor volumes (GTVs), defined as pre- and postoperative gadolinium enhancement on T1-weighted magnetic resonance imaging to biological tumor volumes (BTVs), defined by the uptake of 18F fluoroethyltyrosine (FET) for the radiotherapy planning of high-grade glioma, using a dedicated positron emission tomography (PET)-CT scanner equipped with three triangulation lasers for patient positioning. Methods Nineteen patients with malignant glioma were...

  19. Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography

    DEFF Research Database (Denmark)

    Christensen, Anders Nymark; Rydhög, J. S.; Søndergaard, Rikke Vicki;

    2016-01-01

    Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver......, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy...

  20. Positron emission tomography in cases of chorea with different underlying diseases.

    OpenAIRE

    Hosokawa, S.; Ichiya, Y; Kuwabara, Y; Ayabe, Z; Mitsuo, K; Goto, I; Kato, M.

    1987-01-01

    Local cerebral metabolic rate for glucose (LCMRglc) was measured with positron emission tomography using the 18F-fluorodeoxy-glucose method in five patients with chorea due to different underlying diseases. Hypometabolism was observed in the striatum bilaterally in patients with Huntington's disease, choreoacanthocytosis, sporadic progressive chorea and dementia, and pseudo-Huntington form of dentato-rubro-pallido-luysian atrophy (DRPLA). The patient with hemichorea showed hypometabolism in t...

  1. Noninvasive measurement of regional myocardial glucose metabolism by positron emission computed tomography

    International Nuclear Information System (INIS)

    While the results of regional myocardial glucose metabolism measurements using positron emission computed tomography (13N-ammonia) are promising, their utility and value remains to be determined in man. If this technique can be applied to patients with acute myocardial ischemia or infarction it may permit delineation of regional myocardial segments with altered, yet still active metabolism. Further, it may become possible to evaluate the effects of interventions designed to salvage reversibly injured myocardium by this technique

  2. Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET)

    OpenAIRE

    Levin, Craig S; Virginia Ch. Spanoudaki

    2010-01-01

    We present the most recent advances in photo-detector design employed in time of flight positron emission tomography (ToF-PET). PET is a molecular imaging modality that collects pairs of coincident (temporally correlated) annihilation photons emitted from the patient body. The annihilation photon detector typically comprises a scintillation crystal coupled to a fast photo-detector. ToF information provides better localization of the annihilation event along the line formed by each detector pa...

  3. Gliomatosis cerebri mimicking encephalitis evaluated using fluorine-18 fluorodeoxyglucose: Positron emission tomography/computed tomography

    International Nuclear Information System (INIS)

    Gliomatosis cerebri (GC) is a rare condition in which an infiltrative glial neoplasm spreads through the brain with preservation of the underlying structure. F-18 fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) has an important role in demonstrating the appropriate metabolism and differentiating pathologies mimicking GC on CT and magnetic resonance imaging. We describe imaging findings of FDG PET/CT in GC in a 9-year-old male child mimicking encephalitis

  4. Positron emission tomography-computed tomography has a clinical impact for patients with cervical cancer

    DEFF Research Database (Denmark)

    Sandvik, Rikke Mulvad; Jensen, Pernille Tine; Hendel, Helle W;

    2011-01-01

    Many studies have found that positron emission tomography-computed tomography (PET-CT) has a high sensitivity and specificity in the identification of metastasis in cervical cancer. Herlev Hospital, Denmark, has been performing PET-CTs in stage I-IV cervical cancer since 1 May 2006. The present...... study investigates the positive (PPV) and negative predictive value (NPV) of PET-CT in stage I disease and the clinical impact of the scan results in all disease stages....

  5. Regional structure-function correlations in chronic obstructive lung disease measured with positron emission tomography.

    OpenAIRE

    Brudin, L H; Rhodes, C G; Valind, S O; Buckingham, P D; Jones, T; Hughes, J. M.

    1992-01-01

    BACKGROUND: Positron emission tomography, performed with isotopes of very short half life, can be used to relate local lung tissue density to local ventilation and to the ventilation:perfusion ratio. This method has been used in 10 patients with severe chronic airflow obstruction and differing values for carbon monoxide transfer factor (TLCO) and transfer coefficient (KCO). METHODS: Ventilation (VA) and the ventilation:perfusion ratio (V/Q), lung density, and blood volume were measured region...

  6. Usefulness of myocardial positron emission tomography/nuclear imaging in Takotsubo cardiomyopathy

    Institute of Scientific and Technical Information of China (English)

    Marzia; Testa; Mauro; Feola

    2014-01-01

    AIM:To analyse and summarize all the articles related to positron emission tomography and Takotsubo cardiomyopathy(TTC).METHODS:We performed a systematic review of the existing literature on positron emission tomography/nuclear imaging and Takotsubo cardiomyopathy using PUBMED database.We combined search terms such as"takotsubo","takotsubo syndrome","myocardial positron emission tomography","positron emission tomography".All case reports were excluded.The list included only four articles which were reviewed by two independent investigators.It was not possible to undertake a formal meta-analysis because of the heterogeneity of the studies;therefore,we made a narrative synthesis of the collected data.RESULTS:Nuclear medicine techniques can be useful employed in the differential diagnosis of TTC from an acute coronary syndrome(ACS).In fact,transient left ventricular(LV)apical ballooning is a syndrome frequently misdiagnosed as an ACS and can mimic symptoms of myocardial infarction with ST-T segments changes on electrocardiography(ECG),a limited re-lease of myocardial enzyme,mainly reported after sudden emotional or physical stress,and an akinesis or dyskinesis of the left ventricle apex which are completely reversible in a few weeks.In the studies included in this review,nuclear medicine techniques have demonstrated a discrepancy between normal perfusion and a reduced glucose utilization in TTC,commonly known as"inverse flow metabolism mismatch".This suggests that apical ballooning represents a transient metabolic disorder on the cellular level,rather than a structural contractile disease of the myocardium,due to a transient decrease of glucose metabolism that might be related to a coronary microcirculation impairment followed by prolonged myocardial stunning.CONCLUSION:Nuclear medicine techniques can be usefully used for the diagnosis of TTC and can increase our knowledge of the pathophysiological mechanisms of TTC.

  7. Exogenous lipoid pneumonia with unusual CT pattern and FDG positron emission tomography scan findings

    International Nuclear Information System (INIS)

    We report a case of an exogenous lipoid pneumonia that appeared as a spiculated calcified mass on CT scan in which a positron emission tomography (PET) scan was performed before histological analysis. The F-18 fluoro-deoxy-D-glucose (FDG) PET showed a pattern highly suggestive of malignancy which, to our knowledge, has not yet been described. Similar to inflammatory and infectious lung diseases, lipoid pneumonia may be a false-positive case of F-18 FDG uptake. (orig.)

  8. Exogenous lipoid pneumonia with unusual CT pattern and FDG positron emission tomography scan findings

    Energy Technology Data Exchange (ETDEWEB)

    Tahon, Florence; Berthezene, Yves; Blineau, Nadine; Marchand, Bruno [Department of Radiology, Hopital de la Croix-Rousse, 103 grande rue de la Croix-Rousse, 69317 Lyon Cedex (France); Hominal, Stephane; Guerin, Jean-Claude [Department of Chest, Hopital de la Croix-Rousse, 103 grande rue de la Croix-Rousse, 69317 Lyon Cedex (France); Cinotti, Luc [CERMEP, 59 bd Pinel, 69003 Lyon Cedex (France)

    2002-07-01

    We report a case of an exogenous lipoid pneumonia that appeared as a spiculated calcified mass on CT scan in which a positron emission tomography (PET) scan was performed before histological analysis. The F-18 fluoro-deoxy-D-glucose (FDG) PET showed a pattern highly suggestive of malignancy which, to our knowledge, has not yet been described. Similar to inflammatory and infectious lung diseases, lipoid pneumonia may be a false-positive case of F-18 FDG uptake. (orig.)

  9. Imaging Chronic Pain and Inflammation : Positron Emission Tomography Studies of Whiplash Associated Disorder

    OpenAIRE

    Linnman, Clas

    2008-01-01

    This thesis is on chronic neck pain after a rear impact car injury, so called whiplash associated disorder (WAD). Three empirical studies using positron emission tomography (PET) with different radioligands have been performed. The first study evaluated resting state regional cerebral blood flow (rCBF) in WAD patients and in healthy, pain-free controls, by use of oxygen-15 labeled water. Patients had heightened resting rCBF bilaterally in the posterior parahippocampal and the posterior cingul...

  10. Identifying active vascular micro-calcification by 18F-sodium fluoride positron emission tomography

    OpenAIRE

    Irkle, Agnese; Vesey, Alex T.; Lewis, David Y.; Jeremy N Skepper; Bird, Joseph L. E.; Dweck, Marc R; Joshi, Francis R.; Gallagher, Ferdia A.; Warburton, Elizabeth A; Bennett, Martin R; Kevin M. Brindle; Newby, David E; Rudd, James H.; Davenport, Anthony P.

    2015-01-01

    Vascular calcification is a complex biological process that is a hallmark of atherosclerosis. While macrocalcification confers plaque stability, microcalcification is a key feature of high-risk atheroma and is associated with increased morbidity and mortality. Positron emission tomography and X-ray computed tomography (PET/CT) imaging of atherosclerosis using 18F-sodium fluoride (18F-NaF) has the potential to identify pathologically high-risk nascent microcalcification. However, the precise m...

  11. Identifying active vascular microcalcification by (18)F-sodium fluoride positron emission tomography

    OpenAIRE

    Irkle, Agnese; Vesey, Alex T.; Lewis, David Y.; Jeremy N Skepper; Bird, Joseph L. E.; Dweck, Marc R; Joshi, Francis R.; Gallagher, Ferdia A.; Warburton, Elizabeth A; Bennett, Martin R; Kevin M. Brindle; Newby, David E; Rudd, James H.; Davenport, Anthony P.

    2015-01-01

    Vascular calcification is a complex biological process that is a hallmark of atherosclerosis. While macrocalcification confers plaque stability, microcalcification is a key feature of high-risk atheroma and is associated with increased morbidity and mortality. Positron emission tomography and X-ray computed tomography (PET/CT) imaging of atherosclerosis using (18)F-sodium fluoride ((18)F-NaF) has the potential to identify pathologically high-risk nascent microcalcification. However, the preci...

  12. Clinical Imaging Characteristics of the Positron Emission Mammography Camera: PEM Flex Solo II

    OpenAIRE

    MacDonald, Lawrence; Edwards, John; Lewellen, Thomas; Haseley, David; Rogers, James; Kinahan, Paul

    2009-01-01

    We evaluated a commercial positron emission mammography (PEM) camera, the PEM Flex Solo II. This system comprises two 6 × 16.4 cm detectors that scan together covering up to a 24 × 16.4 cm field of view (FOV). There are no specific standards for testing this detector configuration. We performed several tests important to breast imaging, and we propose tests that should be included in standardized testing of PEM systems.

  13. Fluorodeoxyglucose positron emission tomography-computed tomography findings in a case of xanthogranulomatous pyelonephritis

    OpenAIRE

    Joshi, Prathamesh; Lele, Vikram; Shah, Hardik

    2013-01-01

    Xanthogranulomatous pyelonephritis (XGNP) is an uncommon condition characterized by chronic suppurative renal inflammation that leads to progressive parenchymal destruction. This condition can clinically present as recurrent urinary tract infections, flank pain, hematuria, and occasionally sepsis, and weight loss. This condition is usually associated with obstructing renal calculus. We present 18-fluorodeoxyglucose positron emission tomography-computed tomography (18-FDG PET/CT) findings in a...

  14. Brain Imaging with Positron Emission Tomography: Quantification and Biomedical Applications in Alzheimer's Disease and Brain Tumors

    OpenAIRE

    Wardak, Mirwais

    2013-01-01

    Positron emission tomography (PET) is a unique and powerful imaging technique that is used to visualize and quantify various biological processes in living subjects in health and disease. PET imaging can also provide biological information for the assessment of therapies. In this dissertation, we will cover three projects that utilize the quantitative capability of PET for studying two neurological disorders: Alzheimer's disease and brain tumors.One of the goals in PET imaging is to produce...

  15. Optimization of In-Beam Positron Emission Tomography for Monitoring Heavy Ion Tumor Therapy

    OpenAIRE

    Vieira Crespo, Paulo Alexandre

    2010-01-01

    In-beam positron emission tomography (in-beam PET) is currently the only method for an in-situ monitoring of highly tumor-conformed charged hadron therapy. In such therapy, the clinical effect of deviations from treatment planning is highly minimized by implementing safety margins around the tumor and selecting proper beam portals. Nevertheless, in-beam PET is able to detect eventual, undesirable range deviations and anatomical modifications during fractionated irradiation, to verify the accu...

  16. Transcutaneous measurement of the arterial input function in positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) provides a powerful tool in medical research. Biochemical function can be both precisely localized and quantitatively measured. To achieve reliable quantitation it is necessary to know the time course of activity concentration in the arterial blood during the measurement. In this study the arterial blood curve from the brachial artery is compared to the activity measured in the internal carotid artery with a new transcutaneous detector

  17. Elevated Brain Cannabinoid CB1 Receptor Availability in Posttraumatic Stress Disorder: A Positron Emission Tomography Study

    OpenAIRE

    Neumeister, Alexander; Normandin, Marc D.; Pietrzak, Robert H.; Piomelli, Daniele; Zheng, Ming-Qiang; Gujarro-Anton, Ana; Potenza, Marc N.; Bailey, Christopher R.; Lin, Shu-fei; Najafzadeh, Soheila; Ropchan, Jim; Henry, Shannan; Corsi-Travali, Stefani; Carson, Richard E; Huang, Yiyun

    2013-01-01

    Endocannabinoids and their attending cannabinoid type 1 receptor (CB1) have been implicated in animal models of posttraumatic stress disorder (PTSD). However, their specific role has not been studied in people with PTSD. Herein, we present an in vivo imaging study using positron emission tomography (PET) and the CB1-selective radioligand [11C]OMAR in individuals with PTSD, and healthy controls with lifetime histories of trauma (trauma controls [TC]) and those without such histories (healthy c...

  18. Human hemispheric infarction studied by positron emission tomography and the 15O continuous inhalation technique

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) offers an entirely new approach to the study of the pathophysiology of cerebral ischemic disorders. For the first time it is possible to obtain functional tomographic images that represent cerebral perfusion and metabolism on a regional basis. We report here a study of cerebral blood flow and oxygen extraction by means of the 15O inhalation technique in a large number of human hemispheric infarctions. (orig.)

  19. Synthesis of Novel Neutrophil-Specific Imaging Agents for Positron Emission Tomography (PET) Imaging

    OpenAIRE

    ZHANG Yi; Kundu, Bijoy; Fairchild, Karen D.; Locke, Landon; Berr, Stuart S.; Linden, Joel; Pan, Dongfeng

    2007-01-01

    A neutrophil specific peptide, cinnamoyl-F(D)LF(D)LFK (cFLFLFK), was conjugated consecutively with a polyethylene glycol moiety (3.4 K) and 2,2′,2″,2‴-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA) to form cFLFLFK-PEG-DOTA. After 64Cu labeling, Positron Emission Tomography (PET) imaging was successfully able to detect mouse lung inflammation.

  20. Dynamic positron emission tomography in man using small bismuth germanate crystals

    International Nuclear Information System (INIS)

    Primary considerations for the design of positron emission tomographs for medical studies in humans are the need for high imaging sensitivity, whole organ coverage, good spatial resolution, high maximum data rates, adequate spatial sampling with minimum mechanical motion, shielding against out of plane activity, pulse height discrimination against scattered photons, and timing discrimination against accidental coincidences. We discuss the choice of detectors, sampling motion, shielding, and electronics to meet these objectives

  1. Combined use of positron emission tomography and volume doubling time in lung cancer screening with low-dose CT scanning

    DEFF Research Database (Denmark)

    Ashraf, H; Dirksen, A; Jakobsen, Annika Loft;

    2011-01-01

    In lung cancer screening the ability to distinguish malignant from benign nodules is a key issue. This study evaluates the ability of positron emission tomography (PET) and volume doubling time (VDT) to discriminate between benign and malignant nodules....

  2. Assessment of regional myocardial and renal blood flow with copper-PTSM and positron emission tomography.

    Science.gov (United States)

    Shelton, M E; Green, M A; Mathias, C J; Welch, M J; Bergmann, S R

    1990-09-01

    We recently demonstrated in isolated, perfused hearts that radiolabeled pyruvaldehyde bis(N4-methylthiosemicarbazonato)copper(II) (Cu-PTSM) is well extracted throughout a range of conditions including ischemia, hypoxia, and hyperemia. Once extracted, binding of radioactivity by the isolated heart was essentially irreversible, giving this tracer microspherelike qualities. Because Cu-PTSM can be readily prepared with the generator-produced positron-emitting copper 62 and other gamma- or positron-emitting copper radionuclides, we evaluated its usefulness for measuring regional myocardial and renal blood flow in vivo in intact dogs at rest, after ischemia, or after coronary hyperemia was induced by intravenous administration of dipyridamole. After intravenous administration of radiolabeled Cu-PTSM, the tracer cleared rapidly from the blood. Myocardial uptake of single photon-emitting 67Cu-labeled Cu-PTSM was measured directly in myocardial samples 15 minutes after tracer administration, and it increased proportionally with blood flow throughout the flow range (estimated concomitantly with radiolabeled microspheres) of 0.0-6.0 ml/g/min (n = 340 samples from 17 dogs, r = 0.99, Ycopper radioactivity = 85Xmicrosphere flow -7 chi 2 + 17). Renal uptake of radiolabeled Cu-PTSM was also proportional to blood flow. Positron emission tomography was performed in four intact dogs after intravenous administration of 64Cu-labeled Cu-PTSM (19% positron decay, t1/2 = 12.8 hours). High-quality images of heart and kidney were obtained. Accordingly, radiolabeled Cu-PTSM should be a useful, generator-produced tracer for estimating regional myocardial and renal blood flow with positron emission tomography. PMID:2394015

  3. Optimisation of time resolution in Positron Emission Tomography dedicated to dose control in hadron-therapy

    International Nuclear Information System (INIS)

    Hadron-therapy is a tumor treatment technique based on irradiation by ions beams. The dose distribution can be controlled during the treatment by Positron Emission Tomography (PET). Indeed, the nuclear collisions between the incident ions and the target medium produce β+ emitters, whose spatial distribution is correlated to the dose distribution. However, this application of PET suffers from a low β+ activity, a high parasitic activity, and requires fast reconstruction. The Time-Of-Flight technique appears as a key factor to make the in beam PET technique feasible. This work starts from a front-end concept based on fast digital sampling of the detector signals and digital processing for energy and time extraction. The statistical limitations to time resolution determined by the scintillation process are first examined. An experimental set-up with two scintillation detectors in coincidence is then used to test various algorithms: digital discriminators (leading-edge, constant fraction), and filters (least squares, optimal filter, low-pass interpolating filter). The timing performances of all the algorithms are very similar, except the least squares filter, which is not adapted to the non-stationary noise conditions resulting from the scintillation process. Various scintillator materials and configurations are tested, confirming the importance of light yield, scintillation time constants and photodetector response. An avalanche photodiode detector is tested and used for a multichannel demonstrator, which will be used for in-beam tests. (author)

  4. The electronics system for the LBNL positron emission tomography (PEM) camera

    International Nuclear Information System (INIS)

    We describe the electronics for a high performance Positron Emission Mammography (PEM) camera. It is based on the electronics for a human brain PET camera (the Siemens/CTI HRRT), modified to use a detector module that incorporates a photodiode (PD) array. An ASIC services the PD array, amplifying its signal and identifying the crystal of interaction. Another ASIC services the photomultiplier tube (PMT), measuring its output and providing a timing signal. Field programmable gate arrays (FPGAs) and lookup RAMs are used to apply crystal by crystal correction factors and measure the energy deposit and the interaction depth (based on the PD/PMT ratio). Additional FPGAs provide event multiplexing, derandomization, coincidence detection, and real-time rebinning. Embedded PC/104 microprocessors provide communication, real-time control, and configure the system. Extensive use of FPGAs makes the overall design extremely flexible, allowing many different functions (or design modifications) to be realized without hardware changes. Incorporation of extensive onboard diagnostics, implemented in the FPGAs, is required by the very high level of integration and density achieved by this system

  5. Metabolizer in vivo of fullerenes and metallofullerenes by positron emission tomography

    Science.gov (United States)

    Li, Juan; Yang, Wenjiang; Cui, Rongli; Wang, Dongliang; Chang, Yanan; Gu, Weihong; Yin, Wenyan; Bai, Xue; Chen, Kui; Xia, Lin; Geng, Huan; Xing, Gengmei

    2016-04-01

    Fullerenes (C60) and metallofullerenes (Gd@C82) have similar chemical structure, but the bio-effects of both fullerene-based materials are distinct in vivo. Tracking organic carbon-based materials such as C60 and Gd@C82 is difficult in vivo due to the high content of carbon element in the living tissues themselves. In this study, the biodistribution and metabolism of fullerenes (C60 and Gd@C82) radiolabeled with 64Cu were observed by positron emission tomography (PET). 64Cu-C60 and 64Cu-Gd@C82 were prepared using 1, 4, 7, 10-tetrakis (carbamoylmethyl)-1, 4, 7, 10-tetra-azacyclodo-decanes grafted on carbon cages as a chelator for 64Cu, and were obtained rapidly with high radiochemical yield (≥90%). The new radio-conjugates were evaluated in vivo in the normal mouse model and tissue distribution by small animal PET/CT imaging and histology was carried out. The PET imaging, the biodistribution and the excretion of C60 and Gd@C82 indicated that C60 samples have higher blood retention and lower renal clearance than the Gd@C82 samples in vivo and suggested that the differences in metabolism and distribution in vivo were caused by the structural differences of the groups on the fullerene cages though there is chemical similarity between C60 and Gd@C82.

  6. Tomography by positrons emission: integral unit to the service of Mexico; Tomografia por emision de positrones: unidad integral al servicio de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lopez D, F.A. [Unidad PET-Ciclotron, Facultad de Medicina, UNAM (Mexico)]. e-mail: fred-alonso@correo.unam.mx

    2005-07-01

    The applications of the Positron emission tomography (PET) together with the one radiopharmaceutical 2 - [{sup 18} F]-fluoro-2-deoxy-D-glucose in the area of the medical imaging is expanding quickly and it possesses a bigger impact at the moment in favor of those patient to who suffers an oncological, cardiac or neurological illness in Mexico. (Author)

  7. A positron emission tomography study of nigro-striatal dopaminergic mechanisms underlying attention: implications for ADHD and its treatment

    OpenAIRE

    del Campo, Natalia; Fryer, Tim D; Hong, Young T.; Smith, Rob; Brichard, Laurent; Acosta-Cabronero, Julio; Chamberlain, Samuel R.; Tait, Roger; Izquierdo, David; Regenthal, Ralf; Dowson, Jonathan; Suckling, John; Baron, Jean-Claude; Aigbirhio, Franklin I.; Robbins, Trevor W.

    2013-01-01

    Through the combined use of 18F-fallypride positron emission tomography and magnetic resonance imaging this study examined the neural mechanisms underlying the attentional deficits associated with attention deficit/hyperactivity disorder and their potential reversal with a single therapeutic dose of methylphenidate. Sixteen adult patients with attention deficit/hyperactivity disorder and 16 matched healthy control subjects were positron emission tomography and magnetic resonance imaging scann...

  8. Positron spectroscopy of MDM structures based on strontium titanate monocrystal

    International Nuclear Information System (INIS)

    Macroscopic electric field effect on position of ADAF spectrum center in strontium titanate (ST) monocrystal is investigated. It shows promise of position spectroscopy in study of ferroelectric crystals. Results of studying MDM structures based on ST testify to the fact that under external field effect in ST crystal a negative space charge in structure cathodic psrt is through about. Thermalized positron drift mobility in ST in comparison with electron mobility is anomalously high

  9. High-speed digitization readout of silicon photomultipliers for time of flight positron emission tomography

    International Nuclear Information System (INIS)

    We report on work to develop a system with about 100 picoseconds (ps) time resolution for time of flight positron emission tomography (TOF-PET). The chosen photo detectors for the study were Silicon Photomultipliers (SiPM's). This study was based on extensive experience in studying timing properties of SiPM's. The readout of these devices used the commercial high speed digitizer DRS4. We applied different algorithms to get the best time resolution of 155 ps Guassian (sigma) for a LYSO crystal coupled to a SiPM. We consider the work as a first step in building a prototype TOF-PET module. The field of positron-emission-tomography (PET) has been rapidly developing. But there are significant limitations in how well current PET scanners can reconstruct images, related to how fast data can be acquired, how much volume they can image, and the spatial and temporal resolution of the generated photons. Typical modern scanners now include multiple rings of detectors, which can image a large volume of the patient. In this type of scanner, one can treat each ring as a separate detector and require coincidences only within the ring, or treat the entire region viewed by the scanner as a single 3 dimensional volume. This 3d technique has significantly better sensitivity since more photon pair trajectories are accepted. However, the scattering of photons within the volume of the patient, and the effect of random coincidences limits the technique. The advent of sub-nanosecond timing resolution detectors means that there is potentially much better rejection of scattered photon events and random coincidence events in the 3D technique. In addition, if the timing is good enough, then the origin of photons pairs can be determined better, resulting in improved spatial resolution - so called 'Time-of-Flight' PET, or TOF-PET. Currently a lot of activity has occurred in applications of SiPMs for TOF-PET. This is due to the devices very good time resolution, low profile, lack of high voltage

  10. High-speed digitization readout of silicon photomultipliers for time of flight positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ronzhin, A.; Los, S.; Martens, M.; Ramberg, E.; /Fermilab; Kim, H.; Chen, C.; Kao, C.; /Chicago U.; Niessen, K.; /SUNY, Buffalo; Zatserklyaniy, A.; /Puerto Rico U., Mayaguez; Mazzillo, M.; Carbone, B.; /SGS Thomson, Catania

    2011-02-01

    We report on work to develop a system with about 100 picoseconds (ps) time resolution for time of flight positron emission tomography [TOF-PET]. The chosen photo detectors for the study were Silicon Photomultipliers (SiPM's). This study was based on extensive experience in studying timing properties of SiPM's. The readout of these devices used the commercial high speed digitizer DRS4. We applied different algorithms to get the best time resolution of 155 ps Guassian (sigma) for a LYSO crystal coupled to a SiPM. We consider the work as a first step in building a prototype TOF-PET module. The field of positron-emission-tomography (PET) has been rapidly developing. But there are significant limitations in how well current PET scanners can reconstruct images, related to how fast data can be acquired, how much volume they can image, and the spatial and temporal resolution of the generated photons. Typical modern scanners now include multiple rings of detectors, which can image a large volume of the patient. In this type of scanner, one can treat each ring as a separate detector and require coincidences only within the ring, or treat the entire region viewed by the scanner as a single 3 dimensional volume. This 3d technique has significantly better sensitivity since more photon pair trajectories are accepted. However, the scattering of photons within the volume of the patient, and the effect of random coincidences limits the technique. The advent of sub-nanosecond timing resolution detectors means that there is potentially much better rejection of scattered photon events and random coincidence events in the 3D technique. In addition, if the timing is good enough, then the origin of photons pairs can be determined better, resulting in improved spatial resolution - so called 'Time-of-Flight' PET, or TOF-PET. Currently a lot of activity has occurred in applications of SiPMs for TOF-PET. This is due to the devices very good time resolution, low profile

  11. Value of positron emission tomography and computer tomography (PET/CT) for urologic malignancies; Interet de la tomographie par emission de positons couplee a la scanographie (TEP/TDM) dans les cancers urologiques

    Energy Technology Data Exchange (ETDEWEB)

    Boujelbene, N.; Mirimanoff, R.O.; Ozsahin, M.; Zouhair, A. [Service de radio-oncologie, CHU Vaudois (CHUV), rue du Bugnon 46, CH-1011 Lausanne (Switzerland); Prior, J.O.; Boubaker, A. [Service de medecine nucleaire, CHU Vaudois (CHUV), rue du Bugnon 46, CH-1011 Lausanne (Switzerland); Azria, D. [Service de radio-oncologie, CRLC Val d' Aurelle-Paul-Lamarque, rue Croix-Verte, parc Euromedecine, 34298 Montpellier cedex 5 (France); Universite Montpellier I, 5, boulevard Henri-IV, CS 19044, 34967 Montpellier cedex (France); Schaffer, M. [Service de radio-oncologie, Ludwig-Maximilians-Universitaet Muenchen, Marchioninistr. 15, 81377 Munich (Germany); Gez, E. [Service de radio-oncologie, The Tel Aviv Sourasky Medical Center, 6 Weizmann Street, Tel Aviv 64239 (Israel); Jichlinski, P. [Service d' urologie, CHU Vaudois (CHUV), rue du Bugnon 46, CH-1011 Lausanne (Switzerland); Meuwly, J.Y. [Service de radiologie, CHU Vaudois (CHUV), rue du Bugnon 46, CH-1011 Lausanne (Switzerland)

    2011-07-15

    Positron emission tomography is a functional imaging technique that allows the detection of the regional metabolic rate, and is often coupled with other morphological imaging technique such as computed tomography. The rationale for its use is based on the clearly demonstrated fact that functional changes in tumor processes happen before morphological changes. Its introduction to the clinical practice added a new dimension in conventional imaging techniques. This review presents the current and proposed indications of the use of positron emission/computed tomography for prostate, bladder and testes, and the potential role of this exam in radiotherapy planning. (authors)

  12. High-resolution PET [Positron Emission Tomography] for Medical Science Studies

    Science.gov (United States)

    Budinger, T. F.; Derenzo, S. E.; Huesman, R. H.; Jagust, W. J.; Valk, P. E.

    1989-09-01

    One of the unexpected fruits of basic physics research and the computer revolution is the noninvasive imaging power available to today's physician. Technologies that were strictly the province of research scientists only a decade or two ago now serve as the foundations for such standard diagnostic tools as x-ray computer tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), ultrasound, single photon emission computed tomography (SPECT), and positron emission tomography (PET). Furthermore, prompted by the needs of both the practicing physician and the clinical researcher, efforts to improve these technologies continue. This booklet endeavors to describe the advantages of achieving high resolution in PET imaging.

  13. Patient radiation protection in positron emission tomography; Proteccion radiologica del paciente en la tomografia por emision de positrones

    Energy Technology Data Exchange (ETDEWEB)

    Marti-Climent, J. M.; Garcia-Velloso, M. J. [Universidad de Navarra. (Spain)

    2003-07-01

    Patient radiation protection in Positron Emission Tomography (PET) is closely related to the correct execution of studies: proper scanner performance, and optimization of both image quality and patient dose. We describe the quality control tests considered as essential: scanner stability, spatial resolution, sensitivity and tomographic uniformity. Knowledge of the dose received by the critical organ and the effective dose for each radiopharmaceutical allows the establishment of strategies for dose optimization. Although a great variety of PET tracers exist, we review the dose produced by F-FDG, the most widely used tracer, and those used in our PET Center O-Water, N-Ammonia, C-Methionine, C-Choline, F-Choline, F-Dopa, and F-FHBG. Reduction of administered activity to the patient is the direct way to reduce the dose. Thus, PET acquisition in the 3D mode, with higher sensitivity, is a determining factor. In order to reduce the dose to different organs, efforts should be directed to the critical organs, mainly the urinary bladder wall. Finally, correct patient preparation improves, PET image quality, due to an optimum tracer uptake, which optimizes the dose to different organs. (Author) 25 refs.

  14. A fast rebinning algorithm for 3D positron emission tomography using John's equation

    Science.gov (United States)

    Defrise, Michel; Liu, Xuan

    1999-08-01

    Volume imaging in positron emission tomography (PET) requires the inversion of the three-dimensional (3D) x-ray transform. The usual solution to this problem is based on 3D filtered-backprojection (FBP), but is slow. Alternative methods have been proposed which factor the 3D data into independent 2D data sets corresponding to the 2D Radon transforms of a stack of parallel slices. Each slice is then reconstructed using 2D FBP. These so-called rebinning methods are numerically efficient but are approximate. In this paper a new exact rebinning method is derived by exploiting the fact that the 3D x-ray transform of a function is the solution to the second-order partial differential equation first studied by John. The method is proposed for two sampling schemes, one corresponding to a pair of infinite plane detectors and another one corresponding to a cylindrical multi-ring PET scanner. The new FORE-J algorithm has been implemented for this latter geometry and was compared with the approximate Fourier rebinning algorithm FORE and with another exact rebinning algorithm, FOREX. Results with simulated data demonstrate a significant improvement in accuracy compared to FORE, while the reconstruction time is doubled. Compared to FOREX, the FORE-J algorithm is slightly less accurate but more than three times faster.

  15. Clinical impact of Positron Emission Tomography (PET) on oncological patients and their potentially application context

    International Nuclear Information System (INIS)

    (PET) Positron Emission Tomography is a technique of nuclear medicine that has ability of detecting cancer through mechanisms based on molecular alterations of neoplastic processes. This review describes the PET Oncology applications and discusses the potential application of this technology in the sanitary and national academic framework . The most widely used in Oncology plotter is an analogue of laglucosa labelled with fluo: 18F-2-fluoro-2-Deoxy-D-glucose (FDG). In this way, the PET detects tumour retention of FDG, due to the highest glycolytic of cancer cells. In addition, the PET allow the study of the entire body at the same exploratory and some teams are coupled to systems of axial tomography (PET-CT). By ET-FDG, it is possible to diagnose, staging and restaged the majority of cancers, with diagnostic accuracy close to 90 per cent higher than the values provided by the conventional imaging techniques such. It is also possible to know early response to cancer treatments and obtain relevant medical prognosis information. (author)

  16. Attenuation correction with region growing method used in the positron emission mammography imaging system

    Science.gov (United States)

    Gu, Xiao-Yue; Li, Lin; Yin, Peng-Fei; Yun, Ming-Kai; Chai, Pei; Huang, Xian-Chao; Sun, Xiao-Li; Wei, Long

    2015-10-01

    The Positron Emission Mammography imaging system (PEMi) provides a novel nuclear diagnosis method dedicated for breast imaging. With a better resolution than whole body PET, PEMi can detect millimeter-sized breast tumors. To address the requirement of semi-quantitative analysis with a radiotracer concentration map of the breast, a new attenuation correction method based on a three-dimensional seeded region growing image segmentation (3DSRG-AC) method has been developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuity property of the segmentation result makes this new method free of activity variation of breast tissues. The threshold value chosen is the key process for the segmentation method. The first valley in the grey level histogram of the reconstruction image is set as the lower threshold, which works well in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution determination. Attenuation correction also improves the probability of detecting small and early breast tumors. Supported by Knowledge Innovation Project of The Chinese Academy of Sciences (KJCX2-EW-N06)

  17. Basic principles of positron emission tomography in oncology: Quantitation and whole body techniques

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) of the brain and heart has made important contributions in clinical and research applications in the fields of neurology and cardiology. The more recent applications of PET in tumor imaging has marked oncology as the next frontier in PET; however, the dilemma of rising health care cost will challenge the application of new technologies. This challenge can be approached by innovative and appropriate use of sophisticated technology in both the research and clinical realms. The current developments of PET imaging technology to accurately stage the extent of tumor, as well as monitor the effectiveness or ineffectiveness of new or current therapies will be an extremely valuable tool in research and in the cost effective management of cancer patients. In the future, the oncologist may be able to adjust the chemotherapy to the tumor response based on PET imaging. In other situations, PET may be able to predict that no existing therapy will elicit a durable response, resolving the patients and families uncertainty of whether extreme therapeutic measures would have made a significant difference. This paper reviews some of the recent developments and areas of research in tumor PET imaging, and describes some of the practical and technical aspects involved with FDG tumor quantitation and whole body PET imaging. (authors)

  18. Detection of unknown primary head and neck tumors by positron emission tomography

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the potential of using positron emission tomography (PET) with 18F-labeled fluoro-2-deoxy-D-glucose (FDG) to detect unknown primary tumors of cervical metastases. Thirteen patients with various histologic types of cervical metastases of unknown primary origin were studied. Patients received 185-370 MBq FDG intravenously and were scanned from 30 min after injection onward. Whole-body scans were made with a Siemens ECAT 951/31 PET camera. PET identified the primary tumor in four patients: plasmocytoma, squamous cell cacinoma of the oropharynx, squamous cell carcinoma of the larynx, and bronchial carcinoma, respectively. All known metastatic tumor sites were visualized. PET did not identify a primary tumor in one patient in whom a squamous cell carcinoma at the base of the tongue was found in a latr phase. In the remaining eight patients, a primary lesion was never found. The follow up ranged from 18 to 30 months. A previously unknown primary tumor can be identified with FDG-PET in approximately 30% of patients with cervical metastases. PET can reveal useful information that results in more appropriate treatment, and it can be of value in guiding endoscopic biopsies for histologic diagnosis. (au)

  19. Stochastic algorithms for estimating parameters of compartment analysis of dynamic positron emission tomography data

    International Nuclear Information System (INIS)

    Positron-Emission-Tomography (PET) is a modern medicine technology to gain information about the distribution of biochemical substances in the living human. The substances used for the examination are called tracers and show the metabolic behavior of the substance. The measurement is quantitative so that the dynamics of the metabolization can be calculated by recording a series of pictures. Because of the complex structure and limited spatial and temporal resolution of PET, simplifications have to be introduced to analyze the data. Biomathematical models are used to perform this task. The definition of appropriate models and the estimation of related parameters is called modelling. Its goal is to extract relevant metabolic parameters showing differences in normal or diseased tissue. Models for PET data, especially the mainly used compartment models, are discussed in this paper. Different methods for parameter extraction, i.e. graphical and algebraic nonlinear algorithms, are described in detail. A common problem of the nonlinear parameter estimation is its dependence on starting values. Another problem is the uniqueness of the estimated parameters. These problems are addressed by two new algorithms. They are based on the stochastic approach of simulated annealing. Comparisons to conventional algorithms known from literature are given. The new algorithms show independence of starting values and a better numerical stability. Furthermore, they help with the identification of the parameters. In this way the proposed procedures are regarded as important for the development of new tracers and models. (orig.)

  20. A Delphi study to establish national cost-effectiveness research priorities for positron emission tomography

    International Nuclear Information System (INIS)

    Objective: This study aimed to determine the key cost-effectiveness research questions relating to positron emission tomography (PET) in the UK. Methods: A systematic literature review was conducted to establish the existing knowledge base relating to the cost-effectiveness of PET in the various conditions for which it has been proposed. A three-round postal Delphi study of relevant individuals was used to determine the key cost-effectiveness research questions relating to PET in the UK. The content and structure of the Delphi study was informed by the results of the literature review. Results: The most important cost-effectiveness research priorities for the National Health Service (NHS) relating to PET were in the clinical areas of lung cancer, breast cancer and the assessment of myocardial viability. Gamma camera PET using coincidence imaging was highlighted as a modality whose clinical role needed to be determined urgently. Conclusion: Underlying the cost-effectiveness research priorities which were established is the need for evidence that the use of the various PET modalities as a diagnostic technique will alter patient management as compared to existing diagnostic strategies. The findings of the project provide a contemporary overview of the potential role for PET in the NHS and will be relevant to other countries

  1. Proximal methods for the resolution of inverse problems: application to positron emission tomography

    International Nuclear Information System (INIS)

    The objective of this work is to propose reliable, efficient and fast methods for minimizing convex criteria, that are found in inverse problems for imagery. We focus on restoration/reconstruction problems when data is degraded with both a linear operator and noise, where the latter is not assumed to be necessarily additive.The reliability of the method is ensured through the use of proximal algorithms, the convergence of which is guaranteed when a convex criterion is considered. Efficiency is sought through the choice of criteria adapted to the noise characteristics, the linear operators and the image specificities. Of particular interest are regularization terms based on total variation and/or sparsity of signal frame coefficients. As a consequence of the use of frames, two approaches are investigated, depending on whether the analysis or the synthesis formulation is chosen. Fast processing requirements lead us to consider proximal algorithms with a parallel structure. Theoretical results are illustrated on several large size inverse problems arising in image restoration, stereoscopy, multi-spectral imagery and decomposition into texture and geometry components. We focus on a particular application, namely Positron Emission Tomography (PET), which is particularly difficult because of the presence of a projection operator combined with Poisson noise, leading to highly corrupted data. To optimize the quality of the reconstruction, we make use of the spatio-temporal characteristics of brain tissue activity. (author)

  2. Design of a super fast three-dimensional projection system for positron emission tomography

    International Nuclear Information System (INIS)

    A hardware architecture for rapid three-dimensional (3D) reconstruction is considered for positron emission tomography (PET). For possibly improved PET performance, obliquely oriented lines of response (LOR) are to be collected and properly utilized by one of several experimental 3D reconstruction algorithms. Image signal-to-noise may improve. Septa removal increases the signal by allowing extra LOR collection but also increases the noise due to reduced shielding against out-of-plane events. Primary utility for all LOR collection and 3D reconstruction algorithms may lie with count starved applications. A major obstacle is the time required to compute the 3D reconstruction. Several hours are required even for general purpose computers capable of several million instructions power second. The bulk of the computations for the various reconstruction algorithms are typically in support of forward and back projection. This paper describes a VLSI based architecture which will support forward and back projection for a 3D image and 4096 2D views totaling over 25 million lines of response projected into 0.5 million voxels

  3. Role of positron emission tomography-computed tomography in non-small cell lung cancer.

    Science.gov (United States)

    Garg, Pankaj Kumar; Singh, Saurabh Kumar; Prakash, Gaurav; Jakhetiya, Ashish; Pandey, Durgatosh

    2016-03-26

    Lung cancer is the leading cause of cancer-related mortality worldwide. Non-small cell carcinoma and small cell carcinoma are the main histological subtypes and constitutes around 85% and 15% of all lung cancer respectively. Multimodality treatment plays a key role in the successful management of lung cancer depending upon the histological subtype, stage of disease, and performance status. Imaging modalities play an important role in the diagnosis and accurate staging of the disease, in assessing the response to neoadjuvant therapy, and in the follow-up of the patients. Last decade has witnessed voluminous upsurge in the use of positron emission tomography-computed tomography (PET-CT); role of PET-CT has widened exponentially in the management of lung cancer. The present article reviews the role of 18-fluoro-deoxyglucose PET-CT in the management of non small cell lung cancer with emphasis on staging of the disease and the assessment of response to neoadjuvant therapy based on available literature. PMID:27018223

  4. Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography.

    Science.gov (United States)

    Christensen, A N; Rydhög, J S; Søndergaard, R V; Andresen, T L; Holm, S; Munck Af Rosenschöld, P; Conradsen, K; Jølck, R I

    2016-06-01

    Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive (106)Ag, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy (10- and 22 Gy) in a high-energy beam setting (18 MV). The developed silver-nanosensor provided high radiopacity on the planning CT-scans sufficient for patient positioning in image-guided radiotherapy and provided dosimetric information about the absorbed dose with a 10% and 8% standard deviation for the stereotactic regimens, 10 and 22 Gy, respectively. PMID:27174233

  5. Synthesis and Evaluation of Novel Radioligands Based on 3-[5-(Pyridin-2-yl)-2H-tetrazol-2-yl]benzonitrile for Positron Emission Tomography Imaging of Metabotropic Glutamate Receptor Subtype 5.

    Science.gov (United States)

    Shimoda, Yoko; Yamasaki, Tomoteru; Fujinaga, Masayuki; Ogawa, Masanao; Kurihara, Yusuke; Nengaki, Nobuki; Kumata, Katsushi; Yui, Joji; Hatori, Akiko; Xie, Lin; Zhang, Yiding; Kawamura, Kazunori; Zhang, Ming-Rong

    2016-04-28

    We found out 3-[5-(pyridin-2-yl)-2H-tetrazol-2-yl]benzonitrile analogues as the candidate for positron emission tomography (PET) imaging agents of metabotropic glutamate receptor subtype 5 (mGluR5). Among these compounds, 3-methyl-5-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)benzonitrile (10) exhibited high binding affinity (Ki = 9.4 nM) and moderate lipophilicity (cLogD, 2.4). Subsequently, [(11)C]10 was radiosynthesized at 25 ± 14% radiochemical yield (n = 11) via C-[(11)C]methylation of the arylstannyl precursor 15 with [(11)C]methyl iodide. In vitro autoradiography and PET assessments using [(11)C]10 showed high specific binding in the striatum and hippocampus, two brain regions enriched with mGluR5. Moreover, test-retest PET studies with [(11)C]10 indicated high reliability to quantify mGluR5 density, such as the intraclass correlation coefficient (0.90) and Pearson r (0.91) in the striatum of rat brain. We demonstrated that [(11)C]10 is a useful PET ligand for imaging and quantitative analysis of mGluR5. Furthermore, [(11)C]10 might be modified using its skeleton as a lead compound. PMID:27015128

  6. 18F-fluorodeoxyglucose positron emission tomography optimizes neoadjuvant chemotherapy for primary breast cancer to achieve pathological complete response

    International Nuclear Information System (INIS)

    The background of this study was to assess the usefulness of positron emission tomography combined with computed tomography using 18F-fluorodeoxyglucose (FDG positron emission tomography (PET)/CT) for optimizing chemotherapy during neoadjuvant chemotherapy for primary breast cancer. One hundred and eight patients (110 tumors) with breast cancer (≥2 cm, stages II and III) received neoadjuvant chemotherapy consisting of an anthracycline-based regimen and taxane. The maximal value of the baseline standardized uptake value (SUV) and the change in SUV after four cycles of an anthracycline-based regimen relative to baseline SUV were assessed for predicting pathological complete response (pCR) after sequential taxane. Tumors with pCR had significantly higher baseline SUV (9.3±3.7 SD) compared to those with non-pCR (7.2±3.8 SD) (p=0.02), but there was a considerable overlap between two groups. On PET scan after four cycles of chemotherapy, thirty-three patients (33.7%) with a 72.1% or greater reduction in SUV were considered as responders and the performance in predicting pCR had a sensitivity of 88.9% and specificity of 78.7%. The baseline SUV could not be a useful indicator for predicting pCR due to the wide range in sensitivity. On the other hand, a relative change in SUV after completion of an anthracycline-based regimen could be useful for predicting pCR. (author)

  7. The CLIC positron source based on compton schemes

    CERN Document Server

    Rinolfi, L; Braun, H; Papaphilippou, Y; Schulte, D; Vivoli, A; Zimmermann, F; Dadoun, O; Lepercq, P; Roux, R; Variola, A; Zomer, F; Pogorelski, I; Yakimenko, V; Gai, W; Liu, W; Kamitani, T; Omori, T; Urakawa, J; Kuriki, M; Takahasi, TM; Bulyak, E; Gladkikh, P; Chehab, R; Clarke, J

    2010-01-01

    The CLIC polarized positron source is based on a positron production scheme in which polarized photons are produced by a Compton process. In one option, Compton backscattering takes place in a so-called “Compton ring”, where an electron beam of 1 GeV interacts with circularly-polarized photons in an optical resonator. The resulting circularly-polarized gamma photons are sent on to an amorphous target, producing pairs of longitudinally polarized electrons and positrons. The nominal CLIC bunch population is 4.2x109 particles per bunch at the exit of the Pre-Damping Ring (PDR). Since the photon flux coming out from a "Compton ring" is not sufficient to obtain the requested charge, a stacking process is required in the PDR. Another option is to use a Compton Energy Recovery Linac (ERL) where a quasicontinual stacking in the PDR could be achieved. A third option is to use a "Compton Linac" which would not require stacking. We describe the overall scheme as well as advantages and constraints of the three option...

  8. High power laser production of short-lived isotopes for positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) is a powerful diagnostic/imaging technique requiring the production of the short-lived positron emitting isotopes 11C, 13N, 15O and 18F by proton irradiation of natural/enriched targets using cyclotrons. The development of PET has been hampered due to the size and shielding requirements of nuclear installations. Recent results show that when an intense laser beam interacts with solid targets, megaelectronvolt (MeV) protons capable of producing PET isotopes are generated. This report describes how to generate intense PET sources of 11C and 18F using a petawatt laser beam. The work describing the laser production of 18F through a (p,n) 18O reaction, and the subsequent synthesis of 2-[18F] is reported for the first time. The potential for developing compact laser technology for this purpose is discussed

  9. Brain energy metabolism and dopaminergic function in Huntington's disease measured in vivo using positron emission tomography

    International Nuclear Information System (INIS)

    A 48-year-old man with typical Huntington's disease was investigated with computed tomography (CT) and positron emission tomography. Regional cerebral blood flow, oxygen extraction, oxygen and glucose utilization, L-Dopa uptake, and dopamine (D2) receptor binding were measured using several positron-labelled tracers. CT showed slight atrophy of the head of caudate but no cortical atrophy, although distinct frontal lobe dysfunction was present on psychometric testing. Oxygen and glucose metabolism and cerebral blood flow were decreased in the striata and to a lesser extent in frontal cortex. Cerebral blood flow was in the low normal range throughout the remainder of the brain. A normal metabolic ratio was found in all regions, since the changes in glucose utilization paralleled those in oxygen consumption. The capacity of the striatum to store dopamine as assessed by L-[18F]-fluorodopa uptake was normal, but dopamine (D2) receptor binding was decreased when compared to normal subjects

  10. Test bench of silicon photomultiplier for positron emission tomography application

    OpenAIRE

    Sanchez Gonzalo, David

    2015-01-01

    Typically the medical imaging devices have been based on scintillator crystals coupled to photomultipliers tubes. But the problems to combine them with high electromagnetic fields and the relatively high cost per unit surface, opens new opportunities on the field for a different type of detector named silicon photomultiplier. These ones offer an alternative solution to combine the high gain of the photomultipliers tubes, and the insensitiveness to the magnetic field, high quantum efficiency a...

  11. The 511 keV emission from positron annihilation in the Galaxy

    CERN Document Server

    Prantzos, N; Bykov, A M; Diehl, R; Ferriere, K; Guessoum, N; Jean, P; Knoedlseder, J; Marcowith, A; Moskalenko, I V; Strong, A; Weidenspointner, G

    2010-01-01

    The first gamma-ray line originating from outside the solar system that was ever detected is the 511 keV emission from positron annihilation in the Galaxy. Despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. Observations in the 1990's with OSSE/CGRO showed that the emission is strongly concentrated towards the Galactic bulge. In the 2000's, the SPI instrument aboard ESA's INTEGRAL gamma-ray observatory allowed scientists to measure that emission across the entire Galaxy, revealing that the bulge/disk luminosity ratio is larger than observed in any other wavelength. This mapping prompted a number of novel explanations, including rather "exotic ones (e.g. dark matter annihilation). However, conventional astrophysical sources, like type Ia supernovae, microquasars or X-ray binaries, are still plausible candidates for a large fraction of the observed total 511 keV emission of the bulge. A closer study of the subject reveals new...

  12. Exhaust catalysis studies using in-situ positron emission

    International Nuclear Information System (INIS)

    In this thesis the kinetics of noble metal catalysts with a formulation related to that of commercial automotive exhaust catalysts, have been examined. The application of a new radioisotope tracer technique in studies of catalyst kinetics is described. Reactant and product molecules were pulsed over a catalyst under conditions such, that the reaction rates were kinetically controlled. Labelling of the reacting molecules enables the in-situ measurement of transient phenomena in a reactor as a function of time and position, if a tomograph is used as detection system. Integral reactor profiles are measured, by which concentration gradients occurring in the reactor can be studied. The large amount of data obtained during each experiment were used to quantify the kinetics. To this end, a refined mathematical model of the kinetics based on the elementary steps of adsorption, desorption and surface reaction was used to simulate the experiments. The experimental conditions in this study were representative for the cold start of a car, when the catalyst is heating up. By applying small catalyst particles and high linear velocities the influence of transport phenomena was excluded so that the experiments were carried out in the kinetically controlled regime. Reaction kinetics of carbon monoxide oxidation by oxygen and nitrogen oxide were studied. Experimental data obtained with surface science techniques were very useful in constructing the kinetic model. By simulating the experiments, the relevant kinetic parameters could be quantified and information on the elementary reaction steps was obtained. Since carbon dioxide adsorbs strongly to the catalyst carrier; 10% carbon dioxide was added to the gas phase (in actual automotive exhaust gas the concentration of carbon dioxide is 10 - 15%). This enabled the determination of the transients due to the interaction of gas components with the catalytically active compounds of the catalyst. (author). 446 refs.; 57 figs.; 21 tabs

  13. Dictionary learning for data recovery in positron emission tomography

    International Nuclear Information System (INIS)

    Compressed sensing (CS) aims to recover images from fewer measurements than that governed by the Nyquist sampling theorem. Most CS methods use analytical predefined sparsifying domains such as total variation, wavelets, curvelets, and finite transforms to perform this task. In this study, we evaluated the use of dictionary learning (DL) as a sparsifying domain to reconstruct PET images from partially sampled data, and compared the results to the partially and fully sampled image (baseline).A CS model based on learning an adaptive dictionary over image patches was developed to recover missing observations in PET data acquisition. The recovery was done iteratively in two steps: a dictionary learning step and an image reconstruction step. Two experiments were performed to evaluate the proposed CS recovery algorithm: an IEC phantom study and five patient studies. In each case, 11% of the detectors of a GE PET/CT system were removed and the acquired sinogram data were recovered using the proposed DL algorithm. The recovered images (DL) as well as the partially sampled images (with detector gaps) for both experiments were then compared to the baseline. Comparisons were done by calculating RMSE, contrast recovery and SNR in ROIs drawn in the background, and spheres of the phantom as well as patient lesions.For the phantom experiment, the RMSE for the DL recovered images were 5.8% when compared with the baseline images while it was 17.5% for the partially sampled images. In the patients’ studies, RMSE for the DL recovered images were 3.8%, while it was 11.3% for the partially sampled images. Our proposed CS with DL is a good approach to recover partially sampled PET data. This approach has implications toward reducing scanner cost while maintaining accurate PET image quantification. (paper)

  14. Influence of slice overlap on positron emission tomography image quality

    Science.gov (United States)

    McKeown, Clare; Gillen, Gerry; Dempsey, Mary Frances; Findlay, Caroline

    2016-02-01

    PET scans use overlapping acquisition beds to correct for reduced sensitivity at bed edges. The optimum overlap size for the General Electric (GE) Discovery 690 has not been established. This study assesses how image quality is affected by slice overlap. Efficacy of 23% overlaps (recommended by GE) and 49% overlaps (maximum possible overlap) were specifically assessed. European Association of Nuclear Medicine (EANM) guidelines for calculating minimum injected activities based on overlap size were also reviewed. A uniform flood phantom was used to assess noise (coefficient of variation, (COV)) and voxel accuracy (activity concentrations, Bq ml-1). A NEMA (National Electrical Manufacturers Association) body phantom with hot/cold spheres in a background activity was used to assess contrast recovery coefficients (CRCs) and signal to noise ratios (SNR). Different overlap sizes and sphere-to-background ratios were assessed. COVs for 49% and 23% overlaps were 9% and 13% respectively. This increased noise was difficult to visualise on the 23% overlap images. Mean voxel activity concentrations were not affected by overlap size. No clinically significant differences in CRCs were observed. However, visibility and SNR of small, low contrast spheres (⩽13 mm diameter, 2:1 sphere to background ratio) may be affected by overlap size in low count studies if they are located in the overlap area. There was minimal detectable influence on image quality in terms of noise, mean activity concentrations or mean CRCs when comparing 23% overlap with 49% overlap. Detectability of small, low contrast lesions may be affected in low count studies—however, this is a worst-case scenario. The marginal benefits of increasing overlap from 23% to 49% are likely to be offset by increased patient scan times. A 23% overlap is therefore appropriate for clinical use. An amendment to EANM guidelines for calculating injected activities is also proposed which better reflects the effect overlap size has

  15. Pharmacokinetics of Genetically Engineered Antibody Forms Using Positron Emission Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Steven M. Larson, M.D. Nai-Kong Cheung, M.D., Ph.D.

    2004-08-31

    In the last grant period we have focused on multi-step targeting methodologies (MST), as a method for delivery of high dose to the tumor, with low dose to the bone marrow. We have explored uptake in colorectal, pancreatic and prostate cancer, using an special preparation, developed in collaboration with NeoRex A high tumor/bone marrow ratio is clearly achieved with MST, but with a cost, namely the higher dose to normal kidney. For this reason, we have in particular, (a) looked dosimetry for both tumor and normal organ, and especially renal dosimetry, which appears to be the target organ, for Y-90. (b) In parallel with this we have explored the dosimetry of very high dose rate radionuclides, including Holmium-166. (c) In addition, with NaiKong Cheung, we have developed a new MST construct based on the anti-GD2 targeting 5F11; (d) we have successfully completed development of s-factor tables for mice. In summary, renal dosimetry is dominated by about 4-5% of the injected dose being held long-term in the renal cortex, probably in the proximal tubule, due to the universal uptake of small proteins. This appears to be a function of a biotynlated protein binding of the strept-avidin construct, to HSP70. This cortical uptake has caused us to reconsider renal dosimetry as a whole, with the smaller mass of the cortex, rather than the whole kidney, as the target organ. These insights into dosimetry will be of great importance as MST, becomes more common in clinical practice.

  16. Positron annihilation in cardo-based polymer membranes.

    Science.gov (United States)

    Kobayashi, Y; Kazama, Shingo; Inoue, K; Toyama, T; Nagai, Y; Haraya, K; Mohamed, Hamdy F M; O'Rouke, B E; Oshima, N; Kinomura, A; Suzuki, R

    2014-06-01

    Positron annihilation lifetime spectroscopy (PALS) is applied to a series of bis(aniline)fluorene and bis(xylidine)fluorene-based cardo polyimide and bis(phenol)fluorene-based polysulfone membranes. It was found that favorable amounts of positronium (Ps, the positron-electron bound state) form in cardo polyimides with the 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) moiety and bis(phenol)fluorene-based cardo polysulfone, but no Ps forms in most of the polyimides with pyromellitic dianhydride (PMDA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BTDA) moieties. A bis(xylidine)fluorene-based polyimide membrane containing PMDA and BTDA moieties exhibits a little Ps formation but the ortho-positronium (o-Ps, the triplet state of Ps) lifetime of this membrane anomalously shortens with increasing temperature, which we attribute to chemical reaction of o-Ps. Correlation between the hole size (V(h)) deduced from the o-Ps lifetime and diffusion coefficients of O2 and N2 for polyimides with the 6FDA moiety and cardo polysulfone showing favorable Ps formation is discussed based on free volume theory of gas diffusion. It is suggested that o-Ps has a strong tendency to probe larger holes in rigid chain polymers with wide hole size distributions such as those containing cardo moieties, resulting in deviations from the previously reported correlations for common polymers such as polystyrene, polycarbonate, polysulfone, and so forth. PMID:24815092

  17. 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography-Based Radiotherapy Target Volume Definition in Non-Small-Cell Lung Cancer: Delineation by Radiation Oncologists vs. Joint Outlining With a PET Radiologist?

    International Nuclear Information System (INIS)

    Purpose: 18F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) has benefits in target volume (TV) definition in radiotherapy treatment planning (RTP) for non-small-cell lung cancer (NSCLC); however, an optimal protocol for TV delineation has not been determined. We investigate volumetric and positional variation in gross tumor volume (GTV) delineation using a planning PET/CT among three radiation oncologists and a PET radiologist. Methods and Materials: RTP PET/CT scans were performed on 28 NSCLC patients (Stage IA-IIIB) of which 14 patients received prior induction chemotherapy. Three radiation oncologists and one PET radiologist working with a fourth radiation oncologist independently delineated the GTV on CT alone (GTVCT) and on fused PET/CT images (GTVPETCT). The mean percentage volume change (PVC) between GTVCT and GTVPETCT for the radiation oncologists and the PVC between GTVCT and GTVPETCT for the PET radiologist were compared using the Wilcoxon signed-rank test. Concordance index (CI) was used to assess both positional and volume change between GTVCT and GTVPETCT in a single measurement. Results: For all patients, a significant difference in PVC from GTVCT to GTVPETCT exists between the radiation oncologist (median, 5.9%), and the PET radiologist (median, -0.4%, p = 0.001). However, no significant difference in median concordance index (comparing GTVCT and GTVFUSED for individual cases) was observed (PET radiologist = 0.73; radiation oncologists = 0.66; p = 0.088). Conclusions: Percentage volume changes from GTVCT to GTVPETCT were lower for the PET radiologist than for the radiation oncologists, suggesting a lower impact of PET/CT in TV delineation for the PET radiologist than for the oncologists. Guidelines are needed to standardize the use of PET/CT for TV delineation in RTP.

  18. 18F-2-Deoxy-2-Fluoro-D-Glucose Positron Emission Tomography: Computed Tomography for Preoperative Staging in Gastric Cancer Patients

    OpenAIRE

    Youn, Seok Hwa; Seo, Kyung Won; Lee, Sang Ho; Shin, Yeon Myung; Yoon, Ki Young

    2012-01-01

    Purpose The use of 18F-2-deoxy-2-fluoro-D-glucose positron emission tomography-computed tomography as a routine preoperative modality is increasing for gastric cancer despite controversy with its usefulness in preoperative staging. In this study we aimed to determine the usefulness of preoperative positron emission tomography-computed tomography scans for staging of gastric cancer. Materials and Methods We retrospectively analyzed 396 patients' positron emission tomography-computed tomography...

  19. The positron camera in nuclear medicine

    International Nuclear Information System (INIS)

    Positron emission tomography is making headway in health care delivery. With improvements in instrumentation and physiologic tracers and with the development of hospital-based compact cyclotrons, 'physiopathologic tomography' is around the corner in nuclear medicine. This paper is a brief review of positron emission tomography: instrumentation and applications

  20. Quantitative evaluation of regional substrate metabolism in the human heart by positron emission tomography

    International Nuclear Information System (INIS)

    Meaning interpretation of metabolic images obtained by positron emission tomography for evaluation of cardiac disease requires a knowledge of the normal variation in regional myocardial substrate metabolism. Recent studies with fluorine-18 (F-18) fluorodeoxyglucose suggest inhomogeneity of myocardial glucose metabolism in the normal human heart, which may relate to substrate availability. Therefore, quantitative evaluation of myocardial oxidative metabolism and glucose metabolism, as derived by dynamic positron emission tomography with carbon-11 (C-11) acetate and F-18 fluorodeoxyglucose, was performed in nine healthy male volunteers. All were studied under tightly controlled metabolic conditions of hyperinsulinemic-euglycemic clamping with and without a concurrent lipid emulsion infusion. Significant inhomogeneity of regional glucose metabolism was noted although it was less than that described under fasting conditions. Glucose utilization was 13% lower in the septum compared with the lateral wall both without and with lipid infusion (0.34 vs. 0.39 mumol/g per min, respectively, p less than 0.05; and 0.33 vs. 0.38 mumol/g per min, respectively, (p less than 0.05)). Relatively decreased septal glucose utilization could not be explained by decreased metabolic demand because C-11 clearance constants were marginally higher in the septum than in the lateral wall in both studies (0.055 vs. 0.054 per min, respectively, p = NS; and 0.061 vs. 0.056 per min, respectively,(p less than 0.05)). Relatively decreased septal glucose utilization could reflect regional variation in substrate use and possible preferential free fatty acid utilization by the septum. These data provide a useful framework for assessing altered cardiac metabolism in disease and support standardization of metabolic conditions during metabolic imaging with positron emission tomography

  1. Quantitative evaluation of regional substrate metabolism in the human heart by positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, R.J.; Herman, W.H.; Kalff, V.; Molina, E.; Wolfe, E.R.; Hutchins, G.; Schwaiger, M. (Department of Internal Medicine, University of Michigan Hospitals, Ann Arbor (USA))

    1991-07-01

    Meaning interpretation of metabolic images obtained by positron emission tomography for evaluation of cardiac disease requires a knowledge of the normal variation in regional myocardial substrate metabolism. Recent studies with fluorine-18 (F-18) fluorodeoxyglucose suggest inhomogeneity of myocardial glucose metabolism in the normal human heart, which may relate to substrate availability. Therefore, quantitative evaluation of myocardial oxidative metabolism and glucose metabolism, as derived by dynamic positron emission tomography with carbon-11 (C-11) acetate and F-18 fluorodeoxyglucose, was performed in nine healthy male volunteers. All were studied under tightly controlled metabolic conditions of hyperinsulinemic-euglycemic clamping with and without a concurrent lipid emulsion infusion. Significant inhomogeneity of regional glucose metabolism was noted although it was less than that described under fasting conditions. Glucose utilization was 13% lower in the septum compared with the lateral wall both without and with lipid infusion (0.34 vs. 0.39 mumol/g per min, respectively, p less than 0.05; and 0.33 vs. 0.38 mumol/g per min, respectively, (p less than 0.05)). Relatively decreased septal glucose utilization could not be explained by decreased metabolic demand because C-11 clearance constants were marginally higher in the septum than in the lateral wall in both studies (0.055 vs. 0.054 per min, respectively, p = NS; and 0.061 vs. 0.056 per min, respectively,(p less than 0.05)). Relatively decreased septal glucose utilization could reflect regional variation in substrate use and possible preferential free fatty acid utilization by the septum. These data provide a useful framework for assessing altered cardiac metabolism in disease and support standardization of metabolic conditions during metabolic imaging with positron emission tomography.

  2. Noninvasive measurement of liver regeneration with positron emission tomography and [2-11C]thymidine

    International Nuclear Information System (INIS)

    The feasibility of liver regeneration determination with [2-11C]thymidine and positron emission tomography was investigated in partially hepatectomized rats. Serial tomographic scans were performed over a 120-minute period after injection of [2-11C]thymidine together with tritium-labeled thymidine. Within 10 minutes after injection, positron emission tomography scans showed a twofold higher hepatic uptake in regenerating than in nonregenerating livers. Time-activity curves over the liver area indicated that the maximal uptake was followed by a faster decrease of 11C radioactivity in controls than in regenerating animals, so that total 11C activity remaining in the liver at 120 minutes accounted for 68% of maximum in regenerating and only 38% in controls. Tissue distribution studies performed at 120 minutes showed that total 11C radioactivity, expressed in percent injected dose per gram, was six times higher in regenerating livers than in controls (0.62% ± 0.07% in regenerating livers and 0.10% ± 0.03% in nonregenerating livers; P less than 0.001) and correlated with 3H radioactivity measured in the nuclear fraction (r = 0.92; P less than 0.001). When the hepatic uptake was expressed in percent of dose per organ, the difference between both groups increased (2.31% ± 0.23% in regenerating livers and 0.29% ± 0.02% in nonregenerating livers; P less than 0.001) because of higher weight of regenerating livers than of nonregenerating livers (3.83 ± 0.11 g in regenerating livers and 2.96 ± 0.16 g in nonregenerating livers; P less than 0.001). In other organs examined, no difference in 11C radioactivity was found between the two groups of rats. These results indicated the potential usefulness of [2-11C]thymidine and positron emission tomography for noninvasive measurement of liver regeneration

  3. FEASIBILITY OF POSITRON EMISSION TOMOGRAPHY OF DOSE DISTRIBUTION IN PROTON BEAM CANCER THERAPY.

    Energy Technology Data Exchange (ETDEWEB)

    BEEBE - WANG,J.J.; DILMANIAN,F.A.; PEGGS,S.G.; SCHLYEER,D.J.; VASKA,P.

    2002-06-03

    Proton therapy is a treatment modality of increasing utility in clinical radiation oncology mostly because its dose distribution conforms more tightly to the target volume than x-ray radiation therapy. One important feature of proton therapy is that it produces a small amount of positron-emitting isotopes along the beam-path through the non-elastic nuclear interaction of protons with target nuclei such as {sup 12}C, {sup 14}N, and {sup 16}O. These radioisotopes, mainly {sup 11}C, {sup 13}N and {sup 15}O, allow imaging the therapy dose distribution using positron emission tomography (PET). The resulting PET images provide a powerful tool for quality assurance of the treatment, especially when treating inhomogeneous organs such as the lungs or the head-and-neck, where the calculation of the dose distribution for treatment planning is more difficult. This paper uses Monte Carlo simulations to predict the yield of positron emitters produced by a 250 MeV proton beam, and to simulate the productions of the image in a clinical PET scanner.

  4. Relationship of computed tomography perfusion and positron emission tomography to tumour progression in malignant glioma

    Energy Technology Data Exchange (ETDEWEB)

    Yeung, Timothy P C [London Regional Cancer Program, London Health Sciences Centre, Ontario, Canada, N6A 4L6 (Canada); Robarts Research Institute, The University of Western Ontario, Ontario, Canada, N6A 5B7 (Canada); Department of Medical Biophysics, The University of Western Ontario, Ontario, Canada, N6A 5C1 (Canada); Yartsev, Slav [London Regional Cancer Program, London Health Sciences Centre, Ontario, Canada, N6A 4L6 (Canada); Department of Medical Biophysics, The University of Western Ontario, Ontario, Canada, N6A 5C1 (Canada); Department of Oncology, The University of Western Ontario, London Health Sciences Centre, London Regional Cancer Program, Ontario, Canada, N6A 4L6 (Canada); Lee, Ting-Yim [Robarts Research Institute, The University of Western Ontario, Ontario, Canada, N6A 5B7 (Canada); Department of Medical Biophysics, The University of Western Ontario, Ontario, Canada, N6A 5C1 (Canada); Department of Oncology, The University of Western Ontario, London Health Sciences Centre, London Regional Cancer Program, Ontario, Canada, N6A 4L6 (Canada); Department of Medical Imaging, The University of Western Ontario, London Health Sciences Centre, Victoria Hospital, Ontario, Canada, N6A 5W9 (Australia); Lawson Health Research Institute, St. Joseph' s Health Care London, Ontario, Canada, N6A 4V2 (Canada); Wong, Eugene [London Regional Cancer Program, London Health Sciences Centre, Ontario, Canada, N6A 4L6 (Canada); Department of Oncology, The University of Western Ontario, London Health Sciences Centre, London Regional Cancer Program, Ontario, Canada, N6A 4L6 (Canada); Department of Physics and Astronomy, The University of Western Ontario, Ontario, Canada, N6A 3K7 (Canada); He, Wenqing [Department of Statistical and Actuarial Sciences, The University of Western Ontario, Ontario, Canada, N6A 5B7 (Canada); Fisher, Barbara; VanderSpek, Lauren L [London Regional Cancer Program, London Health Sciences Centre, Ontario, Canada, N6A 4L6 (Canada); Department of Oncology, The University of Western Ontario, London Health Sciences Centre, London Regional Cancer Program, Ontario, Canada, N6A 4L6 (Canada); Macdonald, David [London Regional Cancer Program, London Health Sciences Centre, Ontario, Canada, N6A 4L6 (Canada); Department of Oncology, The University of Western Ontario, London Health Sciences Centre, London Regional Cancer Program, Ontario, Canada, N6A 4L6 (Canada); Department of Clinical Neurological Sciences, The University of Western Ontario, London Health Sciences Centre, University Hospital, Ontario, Canada, N6A 5A5 (Canada); Bauman, Glenn, E-mail: glenn.bauman@lhsc.on.ca [London Regional Cancer Program, London Health Sciences Centre, Ontario, Canada, N6A 4L6 (Canada); Department of Medical Biophysics, The University of Western Ontario, Ontario, Canada, N6A 5C1 (Canada); Department of Oncology, The University of Western Ontario, London Health Sciences Centre, London Regional Cancer Program, Ontario, Canada, N6A 4L6 (Canada)

    2014-02-15

    Introduction: This study aimed to explore the potential for computed tomography (CT) perfusion and 18-Fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting sites of future progressive tumour on a voxel-by-voxel basis after radiotherapy and chemotherapy. Methods: Ten patients underwent pre-radiotherapy magnetic resonance (MR), FDG-PET and CT perfusion near the end of radiotherapy and repeated post-radiotherapy follow-up MR scans. The relationships between these images and tumour progression were assessed using logistic regression. Cross-validation with receiver operating characteristic (ROC) analysis was used to assess the value of these images in predicting sites of tumour progression. Results: Pre-radiotherapy MR-defined gross tumour; near-end-of-radiotherapy CT-defined enhancing lesion; CT perfusion blood flow (BF), blood volume (BV) and permeability-surface area (PS) product; FDG-PET standard uptake value (SUV); and SUV:BF showed significant associations with tumour progression on follow-up MR imaging (P < 0.0001). The mean sensitivity (±standard deviation), specificity and area under the ROC curve (AUC) of PS were 0.64 ± 0.15, 0.74 ± 0.07 and 0.72 ± 0.12 respectively. This mean AUC was higher than that of the pre-radiotherapy MR-defined gross tumour and near-end-of-radiotherapy CT-defined enhancing lesion (both AUCs = 0.6 ± 0.1, P ≤ 0.03). The multivariate model using BF, BV, PS and SUV had a mean AUC of 0.8 ± 0.1, but this was not significantly higher than the PS only model. Conclusion: PS is the single best predictor of tumour progression when compared to other parameters, but voxel-based prediction based on logistic regression had modest sensitivity and specificity.

  5. Positron emission tomography imaging of tumor angiogenesis with a 66Ga-labeled monoclonal antibody.

    Science.gov (United States)

    Engle, Jonathan W; Hong, Hao; Zhang, Yin; Valdovinos, Hector F; Myklejord, Duane V; Barnhart, Todd E; Theuer, Charles P; Nickles, Robert J; Cai, Weibo

    2012-05-01

    The goal of this study was to develop a (66)Ga-based positron emission tomography (PET) tracer for noninvasive imaging of CD105 expression during tumor angiogenesis, a hallmark of cancer. (66)Ga was produced using a cyclotron with (nat)Zn or isotopically enriched (66)Zn targets. TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA) and labeled with (66)Ga. No difference in CD105 binding affinity or specificity was observed between TRC105 and NOTA-TRC105 based on flow cytometry analysis. Reactivity of (66)Ga for NOTA, corrected to the end of bombardment, was between 74 and 222 GBq/μmol for both target enrichments with 80% radiochemical yield. Serial PET imaging revealed that the murine breast cancer 4T1 tumor uptake of (66)Ga-NOTA-TRC105 was 5.9 ± 1.6, 8.5 ± 0.6, and 9.0 ± 0.6% ID/g at 4, 20, and 36 h postinjection, respectively (n = 4). At the last time point, tumor uptake was higher than that of all organs, which gave excellent tumor contrast with a tumor/muscle ratio of 10.1 ± 1.1. Biodistribution data as measured by gamma counting were consistent with the PET findings. Blocking experiment, control studies with (66)Ga-NOTA-cetuximab, as well as ex vivo histology all confirmed the in vivo target specificity of (66)Ga-NOTA-TRC105. Successful PET imaging with high specific activity (66)Ga (>700 GBq/μmol has been achieved) as the radiolabel opens many new possibilities for future PET research with antibodies or other targeting ligands. PMID:22519890

  6. Enhancement of positron emission tomography-computed tomography image quality using the principle of stochastic resonance

    International Nuclear Information System (INIS)

    Acquisition of higher counts improves visual perception of positron emission tomography-computed tomography (PET-CT) image. Larger radiopharmaceutical doses (implies more radiation dose) are administered to acquire this count in a short time period. However, diagnostic information does not increase after a certain threshold of counts. This study was conducted to develop a post processing method based on principle of “stochastic resonance” to improve visual perception of the PET-CT image having a required threshold counts. PET-CT images (JPEG file format) with low, medium, and high counts in the image were included in this study. The image was corrupted with the addition of Poisson noise. The amplitude of the Poisson noise was adjusted by dividing each pixel by a constant 1, 2, 4, 8, 16, and 32. The best amplitude of the noise that gave best images quality was selected based on high value of entropy of the output image, high value of structural similarity index and feature similarity index. Visual perception of the image was evaluated by two nuclear medicine physicians. The variation in structural and feature similarity of the image was not appreciable visually, but statistically images deteriorated as the noise amplitude increases although maintaining structural (above 70%) and feature (above 80%) similarity of input images in all cases. We obtained the best image quality at noise amplitude “4” in which 88% structural and 95% feature similarity of the input images was retained. This method of stochastic resonance can be used to improve the visual perception of the PET-CT image. This can indirectly lead to reduction of radiation dose

  7. Determination of plasma protein binding of positron emission tomography radioligands by high-performance frontal analysis.

    Science.gov (United States)

    Amini, Nahid; Nakao, Ryuji; Schou, Magnus; Halldin, Christer

    2014-09-01

    Positron emission tomography (PET) is an imaging technique based on the use of radioligands labeled with short lived radionuclides, such as (11)C (t½=20.4min) and (18)F (t½=109.8min), which as a consequence often requires rapid plasma protein binding analysis methods. In addition, PET radioligands can suffer from non-specific binding to the membrane when ultrafiltraion, which is the most commonly used method for measuring protein binding in PET, is employed. In this study a high-performance frontal analysis (HPFA) method based on incorporation of a gel filtration column (discovery(®) BIO GFC 100, 50mm×4.6mm, 5μm, 100Å) into a radio-LC system with phosphate buffered saline (PBS, pH 7.4) at a flow rate of 3ml/min as mobile phase was developed and investigated for four PET radioligands. The minimum injection volume (MIV) of plasma, which is a crucial factor in HPFA, was determined to be 200μl (human), 500μl (monkey), 700μl (human) and 1000μl (monkey) for these four radioligands. The MIV values increased as a higher fraction of the radioligand was present in the protein-free form. The protein binding results obtained were in good agreement with ultrafiltration and the method did not suffer from non-specific binding. The short analysis time (<12min) allowed multiple protein binding measurements during time course of a human [(11)C]PBR28 PET study. PMID:24922085

  8. Relationship of computed tomography perfusion and positron emission tomography to tumour progression in malignant glioma

    International Nuclear Information System (INIS)

    Introduction: This study aimed to explore the potential for computed tomography (CT) perfusion and 18-Fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting sites of future progressive tumour on a voxel-by-voxel basis after radiotherapy and chemotherapy. Methods: Ten patients underwent pre-radiotherapy magnetic resonance (MR), FDG-PET and CT perfusion near the end of radiotherapy and repeated post-radiotherapy follow-up MR scans. The relationships between these images and tumour progression were assessed using logistic regression. Cross-validation with receiver operating characteristic (ROC) analysis was used to assess the value of these images in predicting sites of tumour progression. Results: Pre-radiotherapy MR-defined gross tumour; near-end-of-radiotherapy CT-defined enhancing lesion; CT perfusion blood flow (BF), blood volume (BV) and permeability-surface area (PS) product; FDG-PET standard uptake value (SUV); and SUV:BF showed significant associations with tumour progression on follow-up MR imaging (P < 0.0001). The mean sensitivity (±standard deviation), specificity and area under the ROC curve (AUC) of PS were 0.64 ± 0.15, 0.74 ± 0.07 and 0.72 ± 0.12 respectively. This mean AUC was higher than that of the pre-radiotherapy MR-defined gross tumour and near-end-of-radiotherapy CT-defined enhancing lesion (both AUCs = 0.6 ± 0.1, P ≤ 0.03). The multivariate model using BF, BV, PS and SUV had a mean AUC of 0.8 ± 0.1, but this was not significantly higher than the PS only model. Conclusion: PS is the single best predictor of tumour progression when compared to other parameters, but voxel-based prediction based on logistic regression had modest sensitivity and specificity

  9. Human hemispheric infarction studied by positron emission tomography and the 150 continuous inhalation technique

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) offers an entirely new approach to the study of the pathophysiology of cerebral ischemic disorders. This is so because for the first time it is possible to obtain functional tomographic images that represent cerebral perfusion and metabolism in a regional basis. We report here a study of cerebral blood flow and oxygen extraction by means of the 15O inhalation technique in a large number of human hemispheric infarctions. PET imaging with this non-invasive technique has permitted the description of hitherto unreported focal patterns of changes in the CBF/EO2 couple that may have important pathophysiologic and prognostic implications

  10. Whole Body Muscle Activity during the FIFA 11+ Program Evaluated by Positron Emission Tomography

    OpenAIRE

    Nakase, Junsuke; Inaki, Anri; Mochizuki, Takafumi; Toratani, Tatsuhiro; Kosaka, Masahiro; Ohashi, Yoshinori; Taki, Junichi; Yahata, Tetsutaro; Kinuya, Seigo; Tsuchiya, Hiroyuki

    2013-01-01

    Purpose This study investigated the effect of the FIFA 11+ warm-up program on whole body muscle activity using positron emission tomography. Methods Ten healthy male volunteers were divided into a control group and a group that performed injury prevention exercises (The 11+). The subjects of the control group were placed in a sitting position for 20 min and 37 MBq of 18F-fluorodeoxyglucose (FDG) was injected intravenously. The subjects then remained seated for 45 min. The subjects of the exer...

  11. Dead time correction in positron emission tomograph. A method using single photon rate

    Energy Technology Data Exchange (ETDEWEB)

    Senda, Michio; Yonekura, Yoshiharu; Mukai, Takao; Fujita, Toru; Torizuka, Kanji

    1987-06-01

    The count rate linearity and dead time count losses were evaluated in Positologica III, a wholebody multislice positron emission tomograph, using several kinds of phantoms. A wide variation was observed in the relationship between count loss and true coincidence count rate depending on the source distribution, and the dead time correction using the count rate itself was unsuccessful. Since most count losses of this PET scanner occur when the single photon signals were encoded at the circuitry, we measured the single rate to correct for the count loss. This method enabled dead time correction independent of the distribution of source and attenuation material.

  12. Risk of malignancy in thyroid incidentalomas detected by (18)f-fluorodeoxyglucose positron emission tomography

    DEFF Research Database (Denmark)

    Soelberg, Kerstin; Bonnema, Steen Joop; Brix, Thomas Heiberg;

    2012-01-01

    Background: The expanding use of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) has led to the identification of increasing numbers of patients with an incidentaloma in the thyroid gland. We aimed to review the proportion of incidental thyroid cancers found by (18)F-FDG PET...... uptake, 7 of whom (4.4%) had thyroid malignancy. In the eight studies reporting individual maximum standardized uptake values (SUV(max)), the mean SUV(max) was 4.8 (standard deviation [SD] 3.1) and 6.9 (SD 4.7) in benign and malignant lesions, respectively (p...

  13. Receptor-specific positron emission tomography radiopharmaceuticals: 75Br-labeled butyrophenone neuroleptics

    International Nuclear Information System (INIS)

    Cerebral dopaminergic D2 receptors are involved in several common disease states, such as schizophrenia, Parkinson's disease, and Huntington's chorea. The use of radiolabeled D2 receptor-binding ligands with positron emission tomography (PET) to noninvasively quantitate D2 receptor densities thus has potential application in medicine. Butyrophenone neuroleptics have a high in vitro and in vivo binding affinity for cerebral D2 receptors, and due to the useful chemical and nuclear decay properties of 74Br (76% β+, half-life = 1.6 h), the authors have evaluated radiobrominated bromospiperone (BSP), brombenperidol (BBP), and bromperidol (BP) as radiopharmaceuticals for use with PET

  14. The metabolic landscape of cortico-basal ganglionic degeneration: regional asymmetries studied with positron emission tomography.

    OpenAIRE

    Eidelberg, D.; Dhawan, V; Moeller, J R; Sidtis, J.J.; Ginos, J Z; Strother, S C; Cederbaum, J.; Greene, P; Fahn, S; Powers, J M

    1991-01-01

    Regional metabolic rate for glucose (rCMRGlc) was estimated using [18F]fluorodeoxyglucose (FDG) and positron emission tomography (PET) in five patients (four men, one woman; mean age 68; mean disease duration 2.4 years) with clinical findings consistent with the syndrome of cortico-basal ganglionic degeneration (CBGD). Left-right rCMRGlc asymmetry, (L-R)/(L + R) x 100, was calculated for 13 grey matter regions and compared with regional metabolic data from 18 normal volunteers and nine patien...

  15. A Charge-Sensitive Amplifier Associated with APD or PMT for Positron Emission Tomography Scanners

    OpenAIRE

    Mathez, H; Russo, P.; Lu, G.-N.; Pittet, P.; Quiquerez, L.; Lecoq, J.; Bohner, G.

    2010-01-01

    We present a Charge-Sensitive Amplifier (CSA) to be coupled with a 511-KeV 2-photon detector for positron emission tomography scanners. The circuit has been designed to be associated with an Avalanche Photodiode (APD) or Photo-Multiplier Tube (PMT) with large capacitance. It is a two-stage structure. The input stage consists of a foldedcascode fully-differential part and a common-mode feedback (CMFB) circuit. The output stage employs complementary source followers. The amplifier has been desi...

  16. A Lower-Cost High-Resolution LYSO Detector Development for Positron Emission Mammography (PEM)

    OpenAIRE

    Ramirez, Rocio A.; Zhang, Yuxuan; Liu, Shitao; Li, Hongdi; Baghaei, Hossain; An, Shaohui; Wang, Chao; Jan, Meei-Ling; Wong, Wai-Hoi

    2009-01-01

    In photomultiplier-quadrant-sharing (PQS) geometry for positron emission tomography applications, each PMT is shared by four blocks and each detector block is optically coupled to four round PMTs. Although this design reduces the cost of high-resolution PET systems, when the camera consists of detector panels that are made up of square blocks, half of the PMT’s sensitive window remains unused at the detector panel edge. Our goal was to develop a LYSO detector panel which minimizes the unused ...

  17. Flip-flop phenomenon in systemic sclerosis on fluorodeoxyglucose positron emission tomography/computed tomography

    International Nuclear Information System (INIS)

    Systemic sclerosis (SSc) is a rare autoimmune disease, which may affect multiple organ systems. Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) can demonstrate the degree and anatomical extent of involvement in the entire body and coexisting malignancies in connective tissue diseases. We present a case of SSc with an increased 18F-FDG uptake in the cutaneous and subcutaneous tissues even higher than the neighboring skeletal muscles (“flip-flop phenomenon,” that is, an increased 18F-FDG uptake in the skin but a decreased 18F-FDG uptake in the skeletal muscles)

  18. Benign breast lesions detected by positron emission tomography-computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Benveniste, Ana P., E-mail: apbenveniste@mdanderson.org [Department of Diagnostic Radiology,The University of Texas MD Anderson Cancer Center, Houston, TX (United States); Yang, Wei, E-mail: wyang@mdanderson.org [Department of Diagnostic Radiology,The University of Texas MD Anderson Cancer Center, Houston, TX (United States); Benveniste, Marcelo F., E-mail: mfbenveniste@mdanderson.org [Department of Diagnostic Radiology,The University of Texas MD Anderson Cancer Center, Houston, TX (United States); Mawlawi, Osama R., E-mail: omawlawi@mdanderson.org [Department of imaging physics, The University of Texas MD Anderson Cancer Center, Houston, TX (United States); Marom, Edith M., E-mail: emarom@mdanderson.org [Department of Diagnostic Radiology,The University of Texas MD Anderson Cancer Center, Houston, TX (United States)

    2014-06-15

    {sup 18}F-fluorodeoxyglucose positron emission computed tomography (FDG PET-CT) is widely used in the initial staging and response evaluation of patients with malignancy. This review describes a spectrum of benign breast findings incidentally detected by FDG PET-CT at staging that may be misinterpreted as malignancy. We describe the pattern of distribution and intensity of FDG uptake in a spectrum of benign breast diseases with their corresponding typical morphological imaging characteristics to help the nuclear medicine physician and/or general radiologist identify benign lesions, avoiding unnecessary breast imaging work-up and biopsies.

  19. Chemical neuroanatomy and in vitro receptor autoradiography: A basis for cerebral positron emission tomography

    International Nuclear Information System (INIS)

    We review chemical neuroanatomy and in vitro receptor (IVG) autoradiography as tools for the development of methods suitable for positron emission tomography (PET) studies. The organizations of monoaminergic, cholinergic, γ-aminobutyric acidergic (GABA), and excitatory amino acidergic (EAA) pathways within the central nervous system are summarized, as is the presently accepted classification of GABA and EAA receptors. We describe the technique of IVG and discuss its unique advantages for the selection of possible PET methods. Finally, we discuss receptor changes in Huntington's disease and olivopontocerebellar atrophy, two human diseases for which IVG has suggested possible targets for PET imaging

  20. New developments in molecular imaging: positron emission tomography time-of-flight (TOF-PET)

    International Nuclear Information System (INIS)

    Positron Emission tomography (PET) in increasingly being used in oncology for the diagnosis and staging of disease, as well as in monitoring response to therapy. One of the last advances in PET is the incorporation of Time-of-Flight (TOF) information, which improves the tomographic reconstruction process and subsequently the quality of the final image. In this work, we explain the principles of PET and the fundamentals of TOF-PET. Clinical images are shown in order to illustrate how TOF-PET improves the detectability of small lesions, particularly in patients with high body mass index. (Author) 20 refs

  1. Clinical correlates of decreased anteroposterior metabolic gradients in positron emission tomography (PET) of schizophrenic patients

    International Nuclear Information System (INIS)

    The finding in schizophrenic patients of a reversal of the normal frontal to posterior pattern of brain metabolic activity with positron emission tomography (PET) is of interest, but its relevance to psychopathology is unknown. Using PET, the authors studied 21 patients with chronic schizophrenia and 21 age- and sex-matched control subjects. Although eight of the 21 patients and only one of the control subjects showed a relatively lower anteroposterior metabolic gradient, no clinical correlates of this finding were noted. In addition, cerebral atrophy, as determined by CAT scan, was not associated with this aberrant metabolic pattern

  2. Clinical correlates of decreased anteroposterior metabolic gradients in positron emission tomography (PET) of schizophrenic patients

    Energy Technology Data Exchange (ETDEWEB)

    DeLisi, L.E.; Buchsbaum, M.S.; Holcomb, H.H.; Dowling-Zimmerman, S.; Pickar, D.; Boronow, J.; Morihisa, J.M.; van Kammen, D.P.; Carpenter, W.; Kessler, R.

    1985-01-01

    The finding in schizophrenic patients of a reversal of the normal frontal to posterior pattern of brain metabolic activity with positron emission tomography (PET) is of interest, but its relevance to psychopathology is unknown. Using PET, the authors studied 21 patients with chronic schizophrenia and 21 age- and sex-matched control subjects. Although eight of the 21 patients and only one of the control subjects showed a relatively lower anteroposterior metabolic gradient, no clinical correlates of this finding were noted. In addition, cerebral atrophy, as determined by CAT scan, was not associated with this aberrant metabolic pattern.

  3. Measurement of human blood brain barrier integrity using 11C-inulin and positron emission tomography

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) using 11C-inulin was demonstrated to be applicable to the clinical measurement of blood brain barrier permeability and cerebral interstitial fluid volume. Kinetic data were analyzed by application of a two compartment model, in which blood plasma and interstitial fluid spaces constitute the compartments. The blood activity contribution was subtracted from the PET count with the aid of the 11CO inhalation technique. The values we estimated in a human brain were in agreement with the reported values obtained for animal brains by the use of 14C-inulin. (orig.)

  4. In vivo dopamine receptor assessment for clinical studies using positron emission tomography

    International Nuclear Information System (INIS)

    A discussion is presented of techniques to determine cerebral DA-receptor function in vivo and possible (future) applications of such techniques in clinical studies. A brief summary is given on existing approaches that are of particular clinical interest. The emphasis is laid on the in vivo receptor binding techniques, which have become of clinical interest with the advent of positron emission tomography. Both possibilities and limitations of the present methods to assess DA receptors and possible relationships to pathological or behavioral manifestations are described. (author)

  5. Radiolabeled Phosphonium Salts as Mitochondrial Voltage Sensors for Positron Emission Tomography Myocardial Imaging Agents.

    Science.gov (United States)

    Kim, Dong-Yeon; Min, Jung-Joon

    2016-09-01

    Despite substantial advances in the diagnosis of cardiovascular disease, (18)F-labeled positron emission tomography (PET) radiopharmaceuticals remain necessary to diagnose heart disease because clinical use of current PET tracers is limited by their short half-life. Lipophilic cations such as phosphonium salts penetrate the mitochondrial membranes and accumulate in mitochondria of cardiomyocytes in response to negative inner-transmembrane potentials. Radiolabeled tetraphenylphosphonium cation derivatives have been developed as myocardial imaging agents for PET. In this review, a general overview of these radiotracers, including their radiosynthesis, in vivo characterization, and evaluation is provided and clinical perspectives are discussed. PMID:27540422

  6. Fluorodeoxyglucose positron emission tomography-computed tomography findings in a case of xanthogranulomatous pyelonephritis

    International Nuclear Information System (INIS)

    Xanthogranulomatous pyelonephritis (XGNP) is an uncommon condition characterized by chronic suppurative renal inflammation that leads to progressive parenchymal destruction. This condition can clinically present as recurrent urinary tract infections, flank pain, hematuria, and occasionally sepsis, and weight loss. This condition is usually associated with obstructing renal calculus. We present 18-fluorodeoxyglucose positron emission tomography-computed tomography (18-FDG PET/CT) findings in an elderly male suffering from pyrexia and weight loss and suspected urinary tract infection. PET/CT findings in this case lead to diagnosis of XGNP. This diagnosis should be kept in mind while evaluating similar symptoms and PET/CT scan findings. (author)

  7. Caffeine and human cerebral blood flow: A positron emission tomography study

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decreased paCO2 and increased systolic blood pressure significantly; the change in paCO2 did not account for the change in CBF. Smaller increases in diastolic blood pressure, heart rate, plasma epinephrine and norepinephrine, and subjectively reported anxiety were also observed

  8. Diagnosis of a cardiac angiosarcoma by fluorine-18 fluordeoxyglucose positron emission tomography

    International Nuclear Information System (INIS)

    Cardiac angiosarcoma is a rare tumour entity with a poor prognosis. Early detection is difficult but important for the further course of the disease. We report on a young patient with a tumour of unknown origin and dignity of the right atrium. Magnetic resonance imaging, CT and echocardiography were sufficient in localisation, but no statement on the dignity was possible. Furthermore, staging led to ambiguous results. Malignancy could be proved by fluorine-18 fluordeoxyglucose positron emission tomography, leading to early surgery. Histology revealed a poorly differentiated angiosarcoma. (orig.)

  9. New techniques for positron emission tomography in the study of human neurological disorders

    International Nuclear Information System (INIS)

    We continue our focus to develop more cost effective and efficient means for producing new functionally specific tracers and more simple, less expensive, means for acquiring and interpreting quantitative data. These improved processes are required for the future growth of positron emission tomography (PET) as a sophisticated research meeting and for the transfer of this technology to clinical use. Our approach concentrates on two separate yet related areas, radiosynthesis and data analysis. The program is divided into four subprojects, the first pair related to radiosynthesis, and the second pair related to data analysis. Progress during the past project year has been excellent in both accomplishment and publication record. 26 refs

  10. Characterisation of beta(2)-adrenoceptors, using the agonist [C-11]formoterol and positron emission tomography

    OpenAIRE

    Visser, T J; van Waarde, Aaren; Doze, P; Elsinga, P.H.; van der Mark, Thomas W.; Kraan, Jan; Ensing, Kees; Vaalburg, W.

    1998-01-01

    The agonist radioligand N-[2-hydroxy-5-[1-hydroxy-2-[[2-(4-[C-11]-methoxyphenyl)-1-methylethyl]amino]ethyl]phenyl]formamide ([C-11]formoterol) was synthesised in order to test its ability to visualise pulmonary beta(2)-adrenoceptors in vivo, with positron emission tomography (PET). Formoterol was labelled via reaction of a dibenzyl-protected precursor with [C-11]CH3I. Subsequent deprotection with Pd/C and H-2 yielded [C-11]formoterol in 5-15% (corrected for decay) and the specific activity ra...

  11. Positron emission tomography/computed tomography for optimized colon cancer staging and follow up

    DEFF Research Database (Denmark)

    Engelmann, Bodil Elisabeth; Loft, Annika; Kjær, Andreas;

    2014-01-01

    OBJECTIVES: Optimal management of colon cancer (CC) requires detailed assessment of extent of disease. This study prospectively investigates the diagnostic accuracy of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (PET/CT) for staging and detection of recurrence....../CT diagnosed all relapses detected during the first 2 years. High preoperative TIMP-1 levels were associated with significant hazards toward risk of recurrence and shorter overall survival. CONCLUSIONS: This study indicates PET/CT as a valuable tool for staging and follow up in CC. TIMP-1 provided prognostic...

  12. Brain dopaminergic system changes in drug addiction: a review of positron emission tomography findings.

    Science.gov (United States)

    Hou, Haifeng; Wang, Chunyan; Jia, Shaowei; Hu, Shu; Tian, Mei

    2014-10-01

    Dopamine (DA) is considered crucial for the rewarding effects of drugs of abuse, but its role in addiction remains unclear. Positron emission tomography (PET) is the first technology used for in vivo measurement of components of the dopaminergic system in the human brain. In this article, we review the major findings from PET imaging studies on the involvement of DA in drug addiction, including presynaptic DA synthesis, vesicular monoamine transporter 2, the DA transporter, and postsynaptic DA receptors. These results have corroborated the role of DA in addiction and increased the understanding of its underlying mechanisms. PMID:25260796

  13. Cerebrospinal fluid analysis detects cerebral amyloid-β accumulation earlier than positron emission tomography

    OpenAIRE

    Palmqvist, Sebastian; Mattsson, Niklas; Hansson, Oskar; ,

    2016-01-01

    See Rabinovici (doi:10.1093/brain/aww025) for a scientific commentary on this article. Cerebral accumulation of amyloid-β is thought to be the starting mechanism in Alzheimer’s disease. Amyloid-β can be detected by analysis of cerebrospinal fluid amyloid-β42 or amyloid positron emission tomography, but it is unknown if any of the methods can identify an abnormal amyloid accumulation prior to the other. Our aim was to determine whether cerebrospinal fluid amyloid-β42 change before amyloid PET ...

  14. Distributed microprocessor automation network for synthesizing radiotracers used in positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Russell, J.A.G.; Alexoff, D.L.; Wolf, A.P.

    1984-09-01

    This presentation describes an evolving distributed microprocessor network for automating the routine production synthesis of radiotracers used in Positron Emission Tomography. We first present a brief overview of the PET method for measuring biological function, and then outline the general procedure for producing a radiotracer. The paper identifies several reasons for our automating the syntheses of these compounds. There is a description of the distributed microprocessor network architecture chosen and the rationale for that choice. Finally, we speculate about how this network may be exploited to extend the power of the PET method from the large university or National Laboratory to the biomedical research and clinical community at large. 20 refs. (DT)

  15. Distributed Microprocessor Automation Network for Synthesizing Radiotracers Used in Positron Emission Tomography [PET

    Science.gov (United States)

    Russell, J. A. G.; Alexoff, D. L.; Wolf, A. P.

    1984-09-01

    This presentation describes an evolving distributed microprocessor network for automating the routine production synthesis of radiotracers used in Positron Emission Tomography. We first present a brief overview of the PET method for measuring biological function, and then outline the general procedure for producing a radiotracer. The paper identifies several reasons for our automating the syntheses of these compounds. There is a description of the distributed microprocessor network architecture chosen and the rationale for that choice. Finally, we speculate about how this network may be exploited to extend the power of the PET method from the large university or National Laboratory to the biomedical research and clinical community at large. (DT)

  16. Distributed microprocessor automation network for synthesizing radiotracers used in positron emission tomography

    International Nuclear Information System (INIS)

    This presentation describes an evolving distributed microprocessor network for automating the routine production synthesis of radiotracers used in Positron Emission Tomography. We first present a brief overview of the PET method for measuring biological function, and then outline the general procedure for producing a radiotracer. The paper identifies several reasons for our automating the syntheses of these compounds. There is a description of the distributed microprocessor network architecture chosen and the rationale for that choice. Finally, we speculate about how this network may be exploited to extend the power of the PET method from the large university or National Laboratory to the biomedical research and clinical community at large. 20 refs. (DT)

  17. Preparation of radiopharmaceuticals labelled with bromine positron emitting isotopes for the study of dopaminergic receptors of the central nervous system using positron emission tomography

    International Nuclear Information System (INIS)

    The in vivo study of dopaminergic receptors of the central nervous system using positron emission tomography requires the preparation of radiopharmaceuticals labelled with β+ emitting isotopes. The chemical and pharmacological properties of these ligands are evaluated. Cyclotron produced 75 and 76 bromine β+ emitting isotopes are incorporated into dopaminergic ligands by electrophilic substitution using peracetic acid in a no-carrier added form. Purity, lipophilicity and specific activity are analyzed. Pharmacological criteria (specificity, saturability, displacement, localization) required for ligand-receptor binding studies are evaluated in vitro on striatal membranes and in vivo in the rat. Positron emission tomographic studies show that the study of dopaminergic D2 receptors is possible using 75 and 76 bromine labelled bromospiperone and bromolisuride. These ligands are used in physiological and pharmacological studies of the central nervous system

  18. Monte Carlo noise in full Monte Carlo ML-EM and dual matrix reconstructions in positron emission tomography

    International Nuclear Information System (INIS)

    Monte Carlo (MC) simulations in positron emission tomography (PET) play an important role in detector modeling and algorithm testing. Nowadays, these simulation are also increasingly used for scatter correction during reconstruction. This can be done ideally by using MC simulations to calculate the system matrix including scatter (full matrix approach). Another approach to incorporate MC simulations into the reconstruction is using a MC based projector and attenuation based back-projector, avoiding the storage of the matrix (dual matrix (DM) approach). It appears desirable to compare these two methods for PET and investigate the reconstruction accuracy in the light of MC noise. For this purpose a method to estimate the error introduced by the matrix, the sinogram or the projector based on repeated simulations with different MC seeds is introduced. Simulations of a single ring scanner (due to storage limitations) were performed

  19. What have positron emission tomography and 'Zippy' told us about the neuropharmacology of drug addiction?

    Science.gov (United States)

    Cumming, Paul; Caprioli, Daniele; Dalley, Jeffrey W

    2011-08-01

    Translational molecular imaging with positron emission tomography (PET) and allied technologies offer unrivalled applications in the discovery of biomarkers and aetiological mechanisms relevant to human disease. Foremost among clinical PET findings during the past two decades of addiction research is the seminal discovery of reduced dopamine D(2/3) receptor expression in the striatum of drug addicts, which could indicate a predisposing factor and/or compensatory reaction to the chronic abuse of stimulant drugs. In parallel, recent years have witnessed significant improvements in the performance of small animal tomographs (microPET) and a refinement of animal models of addiction based on clinically relevant diagnostic criteria. This review surveys the utility of PET in the elucidation of neuropharmacological mechanisms underlying drug addiction. It considers the consequences of chronic drug exposure on regional brain metabolism and neurotransmitter function and identifies those areas where further research is needed, especially concerning the implementation of PET tracers targeting neurotransmitter systems other than dopamine, which increasingly have been implicated in the pathophysiology of drug addiction. In addition, this review considers the causal effects of behavioural traits such as impulsivity and novelty/sensation-seeking on the emergence of compulsive drug-taking. Previous research indicates that spontaneously high-impulsive rats--as exemplified by 'Zippy'--are pre-disposed to escalate intravenous cocaine self-administration, and subsequently to develop compulsive drug taking tendencies that endure despite concurrent adverse consequences of such behaviour, just as in human addiction. The discovery using microPET of pre-existing differences in dopamine D(2/3) receptor expression in the striatum of high-impulsive rats suggests a neural endophenotype that may likewise pre-dispose to stimulant addiction in humans. PMID:20846139

  20. Muscle activity during a dash shown by 18F-fluorodeoxyglucose positron emission tomography

    International Nuclear Information System (INIS)

    18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been used to examine muscle activity during running. The dash is a basic activity in various kinds of sports but differs from running in terms of intensity and severity. The purpose of this study was to evaluate muscle activity during running at full speed using FDG PET. Six healthy men were investigated during a dash for 10 min after intravenous injection of FDG (37 MBq). Another six healthy men were studied as controls. PET images were obtained 45 min after the FDG injection. Regions of interest were drawn on the anterior and posterior thighs and the anterior and posterior legs. The standardized uptake value (SUV) was calculated to examine the FDG uptake of muscle tissue per unit volume according to an equation. In the control group, the mean SUVs of the anterior thigh, posterior thigh, anterior leg, and posterior leg were 0.49±0.04, 0.44±0.02, 0.46±0.05, and 0.44±0.07, respectively. In the dash group, the mean SUVs of the anterior thigh, posterior thigh, anterior leg, and posterior leg were 0.74±0.20, 0.79±0.08, 0.61±0.07, and 0.60±0.08, respectively. FDG accumulation of every one of the four compartments in the dash group was significantly higher than that in the control. FDG accumulation of the posterior thigh was significantly higher than that of the anterior and the posterior leg in the dash group (P<0.02). Based on the results of our investigation, posterior thigh muscles were especially active during a dash. (author)

  1. Evaluation of recurrent gastric malignancy with [F-18]-FDG positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jadvar, H.; Tatlidil, R.; Garcia, A.A.; Conti, P.S

    2003-03-01

    AIM: We retrospectively assessed the use of [{sup 18}F] fluorodeoxyglucose positron emission tomography (FDG PET) in the evaluation of recurrent disease in patients with history of gastric malignancy. MATERIALS AND METHODS: Eighteen patients were referred for FDG PET for evaluation of recurrent gastric cancer. Prior treatments included total (n=4) or partial gastrectomy (n=14) followed by chemotherapy alone (n=7) or combined chemoradiation therapy (n=2). The interval between the most recent treatment and PET ranged from 3 months to 2 years. Correlative diagnostic data were available in 16 patients and were all obtained within 3 months of the PET study. Validation was by clinical or imaging follow-up (2-45 months) in 16 patients and histology in two patients. RESULTS: PET was concordant with computed tomography (CT) in 12 patients (5 TP, 6 TN, 1 FN). In one patient with negative imaging studies, an incidental finding of left obstructive uropathy was determined to be due to metastatic ureteral stricture. Discordant imaging findings were present in four patients (22% of total). PET-detected diffuse metastatic lesions in three of these patients with rising serum tumour markers while other imaging studies were negative. Additional chemotherapy was initiated in these three patients (17% of total) based on PET localization of disease. PET and a gastric anastomosis biopsy were negative in another patient with positive CT. The remaining two patients without correlative imaging studies died shortly after positive PET studies with presumed recurrent cancer. CONCLUSION: FDG PET may be useful in the evaluation of recurrent gastric cancer, and can localize the disease when CT is non-diagnostic. Imaging evaluation with PET may also impact on the clinical management of patients with recurrent gastric cancer.

  2. A new iterative reconstruction technique for attenuation correction in high-resolution positron emission tomography

    International Nuclear Information System (INIS)

    A new interative reconstruction technique (NIRT) for positron emission computed tomography (PET), which uses transmission data for nonuniform attenuation correction, is described. Utilizing the general inverse problem theory, a cost functional which includes a noise term was derived. The cost functional was minimized using a weighted-least-square maximum a posteriori conjugate gradient (CG) method. The procedure involves a change in the Hessian of the cost function by adding an additional term. Two phantoms were used in a real data acquisition. The first was a cylinder phantom filled with uniformly distributed activity of 74 MBq of fluorine-18. Two different inserts were placed in the phantom. The second was a Hoffman brain phantom filled with uniformly distributed activity of 7.4 MBq of 18F. Resulting reconstructed images were used to test and compare a new interative reconstruction technique with a standard filtered backprojection (FBP) method. The results confirmed that NIRT, based on the conjugate gradient method, converges rapidly and provides good reconstructed images. In comaprison with standard results obtained by the FBP method, the images reconstructed by NIRT showed better noise properties. The noise was measured as rms% noise and was less, by a factor of 1.75, in images reconstructed by NIRT than in the same images reconstructed by FBP. The distance between the Hoffman brain slice created from the MRI image was 0.526, while the same distance for the Hoffman brain slice reconstructed by NIRT was 0.328. The NIRT method suppressed the propagation of the noise without visible loss of resolution in the reconstructed PET images. (orig.)

  3. A simple and improved digital timing method for positron emission tomography

    International Nuclear Information System (INIS)

    A simple and improved digital timing method was developed for positron emission tomography (PET). This method, the so-called 'initial rise interpolation method', is based on an important characteristic of gamma signals: a properly pre-amplified and sampled gamma signal pulse can be characterized to arrive with an initial rise from the baseline and then reach a maximum rise. The pulse arrival time was obtained by calculating the intersection of the initial rise line with the baseline for each gamma signal pulse. Using an 8-channel 100 MHz free-running ADC and FPGA combined data acquisition (DAQ) card, three digital timing methods were employed to measure the coincidence timing resolution of two types of recently developed 3 mmx3 mm PET sensors (a fast and a slow GAPD). The results showed that the initial rise interpolation method provides the best timing resolution for both types of GAPDs: 0.7 ns FWHM for fast GAPD and 1.5 ns FWHM for slow GAPD (digital CFD: 1.5 and 2.2 ns FWHM; maximum rise interpolation: 1.8 and 2.7 ns FWHM). By implementing the initial rise interpolation method into the FPGA of DAQ card, PET images of two 18F line sources were acquired successfully using a pair of 4x4 GAPD-LYSO array detectors (single pixel size: 3 mmx3 mm). The acquired image spatial resolution was a 3.1 mm FWHM. Furthermore, the simulation was performed to evaluate the effects of the pulse rise time, pulse amplitude and front-end noise level on the timing resolution estimated using the three digital timing methods. In accordance with the measurement results, the simulation results also showed that the initial rise interpolation method provided the best timing resolution. These results show that this simple and improved digital timing method is reliable and useful for the development of high performance PET.

  4. {sup 18}F-fluorodeoxyglucose uptake on positron emission tomography in mucinous adenocarcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Shuji, E-mail: murakamis@kcch.jp [Department of Thoracic Oncology, Kanagawa Cancer Center Hospital (Japan); Saito, Haruhiro; Karino, Fumi; Kondo, Tetsuro; Oshita, Fumihiro; Ito, Hiroyuki; Nakayama, Haruhiko [Department of Thoracic Oncology, Kanagawa Cancer Center Hospital (Japan); Yokose, Tomoyuki [Department of Pathology, Kanagawa Cancer Center Hospital (Japan); Yamada, Kouzo [Department of Thoracic Oncology, Kanagawa Cancer Center Hospital (Japan)

    2013-11-01

    Background: The prognostic value of maximum standardized uptake value (maxSUV) on {sup 18}F-fluorodeoxyglucose positron emission tomography (FDG-PET) is known for localized pulmonary adenocarcinoma, which is most commonly non-mucinous adenocarcinoma. We examined the validity of thin-section computed tomography (TS-CT) and FDG-PET findings in mucinous adenocarcinoma. Materials and Methods: TS-CT and FDG-PET were performed on 25 patients with mucinous lung adenocarcinoma that was subsequently resected between January 2009 and March 2013. Based on the percentage reduction of maximum tumor diameter on the mediastinal window image compared with the diameter on the lung window image on TS-CT, tumors were classified as air-type (≥50%) or solid-type (<50%). All resected specimens were pathologically diagnosed according to the International Association for the Study of Lung Cancer (IASLC) classification, and the diameter of the pathological invasive area was assessed. Results: Most mucinous adenocarcinomas were located in the lower lobe. All except two were classified as solid-type tumor on TS-CT. Multiple regression analysis revealed the correlation of maxSUV with pathological tumor size and diameter of pathological invasive area; these two parameters showed no significant correlation with each other (r = 0.354, p = 0.083). maxSUV was significantly lower for tumors with invasive area ≤5 mm than for tumors with invasive area >5 mm (1.62 vs. 3.77, p = 0.01), but no statistically significant difference was found in terms of other pathological invasive findings such as the presence of lymphatic or vascular invasion, pleural involvement, or predominant histological subtype. Conclusions: Most mucinous adenocarcinomas had appearances of solid-type tumor on TS-CT. maxSUV on FDG-PET indicates the pathological invasive area in mucinous adenocarcinoma as well as non-mucinous adenocarcinoma.

  5. Differentiation of autoimmune pancreatitis from suspected pancreatic cancer by fluorine-18 fluorodeoxyglucose positron emission tomography

    International Nuclear Information System (INIS)

    Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has been widely used for the diagnosis of pancreatic cancer. Because autoimmune pancreatitis is easily misdiagnosed as pancreatic cancer and can be tested for by FDG-PET analysis based on the presence of suspected pancreatic cancer, we attempted to clarify the differences in FDG-PET findings between the two conditions. We compared FDG-PET findings between 15 patients with autoimmune pancreatitis and 26 patients with pancreatic cancer. The findings were evaluated visually or semiquantitatively using the maximum standardized uptake value and the accumulation pattern of FDG. FDG uptake was found in all 15 patients with autoimmune pancreatitis, whereas it was found in 19 of 26 patients (73.1%) with pancreatic cancer. An accumulation pattern characterized by nodular shapes was significantly more frequent in pancreatic cancer, whereas a longitudinal shape indicated autoimmune pancreatitis. Heterogeneous accumulation was found in almost all cases of autoimmune pancreatitis, whereas homogeneous accumulation was found in pancreatic cancer. Significantly more cases of pancreatic cancer showed solitary localization, whereas multiple localization in the pancreas favored the presence of autoimmune pancreatitis. FDG uptake by the hilar lymph node was significantly more frequent in autoimmune pancreatitis than in pancreatic cancer, and uptake by the lachrymal gland, salivary gland, biliary duct, retroperitoneal space, and prostate were seen only in autoimmune pancreatitis. FDG-PET is a useful tool for differentiating autoimmune pancreatitis from suspected pancreatic cancer, if the accumulation pattern and extrapancreatic involvement are considered. IgG4 measurement and other current image tests can further confirm the diagnosis. (author)

  6. Lesion quantification in oncological positron emission tomography: a maximum likelihood partial volume correction strategy.

    Science.gov (United States)

    De Bernardi, Elisabetta; Faggiano, Elena; Zito, Felicia; Gerundini, Paolo; Baselli, Giuseppe

    2009-07-01

    A maximum likelihood (ML) partial volume effect correction (PVEC) strategy for the quantification of uptake and volume of oncological lesions in 18F-FDG positron emission tomography is proposed. The algorithm is based on the application of ML reconstruction on volumetric regional basis functions initially defined on a smooth standard clinical image and iteratively updated in terms of their activity and volume. The volume of interest (VOI) containing a previously detected region is segmented by a k-means algorithm in three regions: A central region surrounded by a partial volume region and a spill-out region. All volume outside the VOI (background with all other structures) is handled as a unique basis function and therefore "frozen" in the reconstruction process except for a gain coefficient. The coefficients of the regional basis functions are iteratively estimated with an attenuation-weighted ordered subset expectation maximization (AWOSEM) algorithm in which a 3D, anisotropic, space variant model of point spread function (PSF) is included for resolution recovery. The reconstruction-segmentation process is iterated until convergence; at each iteration, segmentation is performed on the reconstructed image blurred by the system PSF in order to update the partial volume and spill-out regions. The developed PVEC strategy was tested on sphere phantom studies with activity contrasts of 7.5 and 4 and compared to a conventional recovery coefficient method. Improved volume and activity estimates were obtained with low computational costs, thanks to blur recovery and to a better local approximation to ML convergence. PMID:19673203

  7. Role of (18F) 2-fluoro-2-deoxyglucose positron emission tomography in upper gastrointestinal malignancies

    Institute of Scientific and Technical Information of China (English)

    Elizabeth C Smyth; Manish A Shah

    2011-01-01

    The role of whole-body FDG [(18F) 2-fluoro-2-deoxyglucose] positron emission tomography (PET) scanning as an imaging modality in the management of patients with malignancy has evolved enormously over the past two decades. FDG-PET has demonstrated significant efficacy in the staging, prognostication and detection of occult metastatic disease in malignancies of the gastrointestinal tract, in addition to assessment of the response to cytotoxic chemotherapy in a more timely manner than has traditionally been possible by more conventional imaging tools. The sensitivity and specificity of FDG-PET for the detection and staging of malignancy depend not only on the site and size of the primary tumor and metastases, but also on histological cell type, reflecting underlying disparities in glucose metabolism. The metabolic response to neo-adjuvant chemotherapy or to chemo-radiotherapy in cancers of the gastro-esophageal junction or stomach has been demonstrated in several prospective studies to correlate significantly with both the histological tumor response to treatment and with consequent improvements in overall survival. This may offer a future paradigm of personalized treatment based on the PET response to chemotherapy. FDG-PET has been less successful in efforts to screen for and detect recurrent upper gastrointestinal malignancies, and in the detection of low volume metastatic peritoneal disease. Efforts to improve the accuracy of PET include the use of novel radiotracers such as (18F) FLT (3-deoxy-3-fluorothymidine) or 11C-choline, or fusion PET-CT with concurrent high-resolution computed tomography. This review focuses on the role of FDG-PET scanning in staging and response assessment in malignancies of the upper gastrointestinal tract, specifically gastric, esophageal and pancreas carcinoma.

  8. {sup 18}F-FDG positron emission tomography in the early diagnosis of enterocolitis: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Kresnik, E.; Gallowitsch, H.J.; Igerc, I.; Kumnig, G.; Gomez, I.; Lind, P. [Nuclear Medicine and Special Endocrinology, PET Centre, General Hospital, St. Veiterstrasse 47, 9020 Klagenfurt (Austria); Mikosch, P.; Alberer, D.; Hebenstreit, A. [Department of Internal Medicine and Gastroenterology, General Hospital, Klagenfurt (Austria); Wuertz, F. [Department of Pathology, General Hospital, Klagenfurt (Austria); Kogler, D.; Gasser, J. [Department of Radiology, General Hospital, Klagenfurt (Austria)

    2002-10-01

    Collagenous and eosinophilic colitis are rare diseases characterised by chronic watery diarrhoea. Radiographic evaluation of the gastrointestinal tract and colonoscopy are usually non-diagnostic since as many as one-third of patients will have minor abnormalities. To date a few investigators have reported increased fluorine-18 fluorodeoxyglucose ({sup 18}F-FDG) uptake on positron emission tomography (PET) in patients with acute enterocolitis, but there have been no reports on the use of {sup 18}F-FDG PET for the diagnosis of collagenous or eosinophilic colitis in an early clinical stage. The aim of this preliminary study was to evaluate the usefulness of {sup 18}F-FDG PET in the early diagnosis of patients with colitis. We investigated five women (mean age 61.2{+-}12.1 years) who had been diagnosed as having colitis in an early clinical stage. In all but one of the patients, the diagnosis of colitis was based on biopsy. Magnetic resonance colonography, ultrasonography and colonoscopy were performed in all but one of the patients. Two women were identified as having collagenous colitis in an early clinical stage. Another two patients had eosinophilic colitis. The morphological imaging methods, magnetic resonance colonography and ultrasonography, yielded no suspicious findings, and the results of colonoscopy similarly showed no abnormalities. One patient had colitis due to bacterial infection. In all patients {sup 18}F-FDG PET showed a pathological increase in tracer uptake in the large bowel, suggestive of colitis. In four of the five patients, colitis was confirmed by histology, and in one, by bacterial analysis. {sup 18}F-FDG PET was able to detect colitis in an early clinical stage, when morphological imaging methods and colonoscopy were non-diagnostic. The early performance of {sup 18}F-FDG PET imaging in patients with possible colitis is encouraging. (orig.)

  9. Importance of defect detectability in Positron Emission Tomography imaging of abdominal lesions

    Directory of Open Access Journals (Sweden)

    Shozo Yamashita

    2015-07-01

    Full Text Available Objective(s: This study was designed to assess defect detectability in positron emission tomography (PET imaging of abdominal lesions. Methods: A National Electrical Manufactures Association International Electrotechnical Commission phantom was used. The simulated abdominal lesion was scanned for 10 min using dynamic list-mode acquisition method. Images, acquired with scan duration of 1-10 min, were reconstructed using VUE point HD and a 4.7 mm full-width at half-maximum (FWHM Gaussian filter. Iteration-subset combinations of 2-16 and 2-32 were used. Visual and physical analyses were performed using the acquired images. To sequentially evaluate defect detectability in clinical settings, we examined two middle-aged male subjects. One had a liver cyst (approximately 10 mm in diameter and the other suffered from pancreatic cancer with an inner defect region (approximately 9 mm in diameter. Results: In the phantom study, at least 6 and 3 min acquisition durations were required to visualize 10 and 13 mm defect spheres, respectively. On the other hand, spheres with diameters ≥17 mm could be detected even if the acquisition duration was only 1 min. The visual scores were significantly correlated with background (BG variability. In clinical settings, the liver cyst could be slightly visualized with an acquisition duration of 6 min, although image quality was suboptimal. For pancreatic cancer, the acquisition duration of 3 min was insufficient to clearly describe the defect region. Conclusion: The improvement of BG variability is the most important factor for enhancing lesion detection. Our clinical scan duration (3 min/bed may not be suitable for the detection of small lesions or accurate tumor delineation since an acquisition duration of at least 6 min is required to visualize 10 mm lesions, regardless of reconstruction parameters. Improvements in defect detectability are important for radiation treatment planning and accurate PET-based diagnosis.

  10. Economic analysis of clinical positron emission tomography of the heart with rubidium-82

    International Nuclear Information System (INIS)

    This report describes a cost analysis for clinical positron emission tomography (PET) of the heart using generator produced rubidium-82 (82Rb). Considered sequentially are the clinical problem, current noninvasive radionuclide methods, positron emission tomograph, and the cost of PET per study. Also analyzed are the costs of PET versus thallium imaging in the management of chest pain, for screening asymptomatic men at high risk for coronary artery disease and for evaluating myocardial viability after myocardial infarction or thrombolytic therapy. Noninvasive assessment of coronary artery stenosis and myocardial ischemia/viability in symptomatic or asymptomatic subjects remains a major medical problem because the sensitivity and specificity of thallium imaging are only 70-85% and 50-70%, respectively, in recent studies. Cardiac positron imaging has an accuracy for noninvasive diagnosis of coronary artery disease in symptomatic or asymptomatic patients with a sensitivity and specificity of 95-98%. It can also be used for assessing physiologic stenosis severity, for imaging myocardial infarction and viability, for assessing effects of interventions such as thrombolysis, percutaneous transluminal coronary angioplasty (PTCA) or bypass surgery on myocardial perfusion, metabolism or coronary flow reserve, for assessing collateral function noninvasively in man, and for diagnosing cardiomyopathy not due to coronary artery disease. Although the cost for cardiac PET with 82Rb may be modestly higher than for 201Tl, the greater diagnostic yield of PET results in comparable or lower overall medical management costs than no diagnostic tests/interventions and lower overall costs compared to thallium imaging for evaluating patients with chest pain, asymptomatic high risk males, and patients after acute myocardial infarction/thrombolysis for myocardial viability

  11. Whole body muscle activity during the FIFA 11+ program evaluated by positron emission tomography.

    Directory of Open Access Journals (Sweden)

    Junsuke Nakase

    Full Text Available PURPOSE: This study investigated the effect of the FIFA 11+ warm-up program on whole body muscle activity using positron emission tomography. METHODS: Ten healthy male volunteers were divided into a control group and a group that performed injury prevention exercises (The 11+. The subjects of the control group were placed in a sitting position for 20 min and 37 MBq of (18F-fluorodeoxyglucose (FDG was injected intravenously. The subjects then remained seated for 45 min. The subjects of the exercise group performed part 2 of the 11+for 20 min, after which FDG was injected. They then performed part 2 of the 11+for 20 min, and rested for 25 min in a sitting position. Positron emission tomography-computed tomography images were obtained 50 min after FDG injection in each group. Regions of interest were defined within 30 muscles. The standardized uptake value was calculated to examine the FDG uptake of muscle tissue per unit volume. RESULTS: FDG accumulation within the abdominal rectus, gluteus medius and minimus were significantly higher in the exercise group than in the control group (P<0.05. CONCLUSION: The hip abductor muscles and abdominal rectus were active during part 2 of the FIFA 11+ program.

  12. Catecholamine stimulation, substrate competition, and myocardial glucose uptake in conscious dogs assessed with positron emission tomography

    International Nuclear Information System (INIS)

    Uptake of radiolabelled deoxyglucose out of proportion to reduced coronary flow demonstrated by positron emission tomography has been used to identify reversibly ischemic, viable myocardium. For this concept to be applied reliably in the clinical setting, factors that may depress glucose availability independent of tissue viability, such as adrenergic stimulation and substrate competition, must be examined. Accordingly, we studied the effect of catecholamine stimulation by dopamine on myocardial glucose uptake in vivo using chronically instrumented, intact dogs and positron emission tomography. We measured myocardial activity of [2-18F]-2-deoxyglucose (FDG) and 82Rb in glucose-loaded animals randomly studied during dopamine infusion, during insulin infusion, and then during their combined infusion. Myocardial FDG uptake was significantly decreased when animals were treated with dopamine, compared with treatment in the same animals with insulin. When insulin was added to the dopamine infusion, myocardial FDG uptake was restored. In contrast, myocardial activity of 82Rb, which is taken up in proportion to coronary flow, was similar under all three experimental conditions. Plasma glucose, free fatty acid, and lactate concentrations were determined before and during each infusion. The depression of myocardial FDG activity seen during dopamine infusion and its reversal with addition of insulin can be explained on the basis of effects of these hormones on substrate availability and competition

  13. Diagnostic utility of fluorodeoxyglucose positron emission tomography/computed tomography in pyrexia of unknown origin

    International Nuclear Information System (INIS)

    The present study was undertaken to evaluate the diagnostic utility of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) in patients presenting as pyrexia of unknown origin (PUO). Forty-seven patients (31 males and 16 females; mean age of 42.7 ± 19.96 years) presenting as PUO to the Department of Medicine at the All India Institute of Medical Sciences, New Delhi over a period of 2 years underwent F-18 FDG PET/CT. PET ⁄ CT was considered supportive when its results correlated with the final definitive diagnosis. Final diagnosis was made on the basis of combined evaluation of history, clinical findings, investigations, and response to treatment. Thirty-five PET/CT studies (74.5%) were positive. However, only 18 (38.3%) were supportive of the final diagnosis. In three patients (6.4%), PET/CT was considered diagnostic as none of the other investigations including contrast-enhanced computed tomography of chest and abdomen, and directed tissue sampling could lead to the final diagnosis. All these three patients were diagnosed as aortoarteritis. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography is an important emerging modality in the workup of PUO. It supported the final diagnosis in 38% of our patients and was diagnostic in 6.4% of patients. Thus, PET/CT should only be considered as second-line investigation for the diagnostic evaluation of PUO; especially in suspected noninfectious inflammatory disorders

  14. 55Co-EDTA for renal imaging using positron emission tomography (PET): a feasibility study

    International Nuclear Information System (INIS)

    The feasibility of imaging renal function with 55Co-ethylene diamine tetraacetic acid (EDTA) and dynamic positron emission tomography was investigated. A group of normal Wistar rats was injected intravenously with 55Co-EDTA and underwent dynamic positron emission tomography (PET) imaging in order to study the biodistribution. The time-activity curves of the heart (blood pool), both kidneys, liver, and bladder were observed. In two animals, blood and urinary clearances of 55Co-EDTA were compared with those for 51Cr-EDTA. In one animal, unilateral reduction in kidney function was induced and the right/left ratio for the kidneys was determined. The time-activity curves showed that 55Co-EDTA cleared rapidly from the blood pool (heart), whereas prompt and high target-to-background ratios for both kidneys were obtained. The entire tracer was cleared from the renal parenchyma by urinary excretion and collection of the activity in the bladder. No specific activity uptake was noticed in any other organ or tissue. The clearances of 55Co-EDTA and 51Cr-EDTA in blood were not significantly different, showing that the nature of the M++ has no influence on the in vivo behavior of EDTA. 55Co can be produced easily by cyclotron irradiation and 55Co-EDTA is a promising physiological tracer for nephrological research using PET

  15. Positron emission tomography studies in the normal and abnormal ageing of human brain

    International Nuclear Information System (INIS)

    Until recently, the investigation of the neurophysiological correlates of normal and abnormal ageing of the human brain was limited by methodological constraints, as the technics available provided only a few parameters (e.g. electroencephalograms, cerebral blood flow) monitored in superficial brain structures in a grossly regional and poorly quantitative way. Lately several non invasive techniques have been developed which allow to investigate in vivo both quantitatively and on local basis a number of previously inaccessible important aspects of brain function. Among these techniques, such as single photon emission tomography imaging of computerized electric events, nuclear magnetic resonance, positron emission tomography stands out as the most powerful and promising method since it allows the in vivo measurement of biochemical and pharmacological parameters

  16. Adequacy of compartmental model for positron emission tomography examinations; Adequacao de modelo compartimental para exames de tomografia por emissao de positrons

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Joao Eduardo Maeda Moreira da; Furuie, Sergio Shiguemi [Universidade de Sao Paulo (USP), SP (Brazil). Dept. de Engenharia de Telecomunicacoes e Controle. Lab. de Engenharia Biomedica

    2011-12-15

    The objective of this work is the determination of the most adequate compartmental model for the study of physiological dynamics based on positron emission tomography exams. We propose the use of Akaike's information criterion for the optimal model selection, and Levenberg-Marquardt algorithm with sensitivity equations for the task of estimating the characteristic parameters of the differential equations describing the models. We have considered three compartmental structures represented, respectively, by two compartments and two characteristic constants, three compartments and four characteristic constants and four compartments and six characteristics constants. The data considered in this work were synthesized taking into account key features of a real tomography exam, such as type and level of noise and morphology of the input function of the system. Applying the proposed methodology with three noise levels (low, medium and high), we obtained agreement of the best model with strong and considerable degrees (with Kappa indexes equal to 0.95, 0.93 and 0.63, respectively). It was observed that, with high noise level and more complex models (four compartments), the classification is deteriorated due to lack of data for the decision. Programs have been developed and a graphical interface that can be used in research, development, simulation and parameter identification of compartmental models, supporting analysis of clinical diagnostics and scientific practices. (author)

  17. Bronchial stump aspergillosis after lobectomy for lung cancer as an unusual cause of false positive fluorodeoxyglucose positron emission tomography and computed tomography: a case report

    Directory of Open Access Journals (Sweden)

    Font Albert

    2011-02-01

    Full Text Available Abstract Introduction Bronchial stump aspergillosis is a rare entity characterized by cough and hemoptysis. Case presentation We report the case of a 58-year-old Caucasian woman who developed bronchial stump aspergillosis two years after a left upper lobe resection for lung cancer. Bronchial stump aspergillosis was diagnosed as a result of a focus of increased fluorodeoxyglucose activity in a follow-up positron emission tomography and computed tomography scan. She was treated with oral antifungal therapy and presented with good evolution after three months of treatment. Conclusion Bronchial stump aspergillosis is an unusual complication after pulmonary resection. Clinicians should be aware of it when a local recurrence of cancer around the bronchial stump is suspected based on a positive positron emission tomography and computed tomography finding.

  18. The fast method of Cu-porphyrin complex synthesis for potential use in positron emission tomography imaging

    Science.gov (United States)

    Kilian, Krzysztof; Pęgier, Maria; Pyrzyńska, Krystyna

    2016-04-01

    Porphyrin based photosensitizers are useful agents for photodynamic therapy and fluorescence imaging of cancer. Additionally, porphyrins are excellent metal chelators, forming stable metalo-complexes and 64Cu isotope can serve as a positron emitter (t1/2 = 12.7 h). The other advantage of 64Cu is its decay characteristics that facilitates the use of 64Cu-porphyrin complex as a therapeutic agent. Thus, 64Cu chelation with porphyrin photosensitizer may become a simple and versatile labeling strategy for clinical positron emission tomography. The present study reports a convenient method for the synthesis of Cu complex with tetrakis(4-carboxyphenyl)porphyrin (TCPP). The experimental conditions for labeling, such as the metal-to-ligand molar ratio, pH and time of reaction were optimized to achieve a high complexation efficiency in a short period of time as possible. In order to accelerate the metallation, the use of substitution reactions of cadmium or lead porphyrin and the presence of reducing agent, such as ascorbic acid, hydroxylamine and flavonoid - morin, were evaluated. The optimum conditions for the synthesis of the copper complex were borate buffer at pH 9 with the addition of 10-fold molar excess, with respect to Cu2 + ions and TCPP and ascorbic acid which resulted in reduction of the reaction time from 30 min to below 1 min.

  19. Transfer of learning with an application to the physics of positron emission tomography

    Science.gov (United States)

    Aryal, Bijaya

    2007-12-01

    A series of teaching activities using physical models was developed to present some portions of physics of Positron Emission Tomography (PET) and investigate students' understanding and transfer of learning in physics to a medical technology. A teaching interview protocol consistent with a qualitative research methodology was developed and administered to the students enrolled in an algebra-based introductory level physics course. 16 students participated in individual interviews and another 21 students participated in the group sessions. The major objectives of the teaching interviews were to investigate students' transfer of physics learning from their prior experiences to the provided physical models, from one model to the other and from the models to the PET problems. The study adapted phenomenological research methodology in analyzing students' use of cognitive resources and cognitive strategies during knowledge construction and reconstruction. A resource based transfer model framed under the cognitive theory of learning and consistent with contemporary views of transfer was used to describe the transfer of physics learning. Results of the study indicated both appropriate and inappropriate use of the students' prior conceptual resources in novel contexts. Scaffolding and questioning were found to be effective in activating appropriate and suppressing the inappropriate resources. The physical models used as analogies were found useful in transferring physics learning to understand image construction in PET. Positive transfer was possible when the models were introduced in an appropriate sequence. The results of the study indicate the occurrence of three types of non-scaffolded transfer---spontaneous, semi spontaneous and non-spontaneous. The research found connections between sequencing of hints and phrasing of information in activating students' different conceptual resources. A qualitative investigation based on Vygotsky's Zone of Proximal Development (ZPD

  20. Development of a prototype Open-close positron emission tomography system

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Okumura, Satoshi; Komori, Masataka; Ogata, Yoshimune; Kato, Katsuhiko [Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya (Japan); Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu [Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya (Japan); Hatazawa, Jun [Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka (Japan); Department of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, Osaka (Japan)

    2015-08-15

    We developed a prototype positron emission tomography (PET) system based on a new concept called Open-close PET, which has two modes: open and close-modes. In the open-mode, the detector ring is separated into two halved rings and subject is imaged with the open space and projection image is formed. In the close-mode, the detector ring is closed to be a regular circular ring, and the subject can be imaged without an open space, and so reconstructed images can be made without artifacts. The block detector of the Open-close PET system consists of two scintillator blocks that use two types of gadolinium orthosilicate (GSO) scintillators with different decay times, angled optical fiber-based image guides, and a flat panel photomultiplier tube. The GSO pixel size was 1.6 × 2.4 × 7 mm and 8 mm for fast (35 ns) and slow (60 ns) GSOs, respectively. These GSOs were arranged into an 11 × 15 matrix and optically coupled in the depth direction to form a depth-of-interaction detector. The angled optical fiber-based image guides were used to arrange the two scintillator blocks at 22.5° so that they can be arranged in a hexadecagonal shape with eight block detectors to simplify the reconstruction algorithm. The detector ring was divided into two halves to realize the open-mode and set on a mechanical stand with which the distance between the two parts can be manually changed. The spatial resolution in the close-mode was 2.4-mm FWHM, and the sensitivity was 1.7% at the center of the field-of-view. In both the close- and open-modes, we made sagittal (y-z plane) projection images between the two halved detector rings. We obtained reconstructed and projection images of {sup 18}F-NaF rat studies and proton-irradiated phantom images. These results indicate that our developed Open-close PET is useful for some applications such as proton therapy as well as other applications such as molecular imaging.

  1. Development of a prototype Open-close positron emission tomography system

    International Nuclear Information System (INIS)

    We developed a prototype positron emission tomography (PET) system based on a new concept called Open-close PET, which has two modes: open and close-modes. In the open-mode, the detector ring is separated into two halved rings and subject is imaged with the open space and projection image is formed. In the close-mode, the detector ring is closed to be a regular circular ring, and the subject can be imaged without an open space, and so reconstructed images can be made without artifacts. The block detector of the Open-close PET system consists of two scintillator blocks that use two types of gadolinium orthosilicate (GSO) scintillators with different decay times, angled optical fiber-based image guides, and a flat panel photomultiplier tube. The GSO pixel size was 1.6 × 2.4 × 7 mm and 8 mm for fast (35 ns) and slow (60 ns) GSOs, respectively. These GSOs were arranged into an 11 × 15 matrix and optically coupled in the depth direction to form a depth-of-interaction detector. The angled optical fiber-based image guides were used to arrange the two scintillator blocks at 22.5° so that they can be arranged in a hexadecagonal shape with eight block detectors to simplify the reconstruction algorithm. The detector ring was divided into two halves to realize the open-mode and set on a mechanical stand with which the distance between the two parts can be manually changed. The spatial resolution in the close-mode was 2.4-mm FWHM, and the sensitivity was 1.7% at the center of the field-of-view. In both the close- and open-modes, we made sagittal (y-z plane) projection images between the two halved detector rings. We obtained reconstructed and projection images of 18F-NaF rat studies and proton-irradiated phantom images. These results indicate that our developed Open-close PET is useful for some applications such as proton therapy as well as other applications such as molecular imaging

  2. Contribution of 18F-fluorodeoxyglucose positron emission tomography in the detection and evaluation of peritoneal metastasis in colorectal cancer

    International Nuclear Information System (INIS)

    Accurate detection of peritoneal metastasis in colorectal cancer remains a diagnostic challenge. The accuracy of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the diagnosis of peritoneal recurrence was evaluated, FDG-PET was conducted in 18 patients previously treated for colorectal cancer and suspected recurrence with clinical symptoms, computed tomography (CT), and tumor markers. Final Diagnosis was obtained by histological evaluation (n=14) or clinical follow-up (n=4). FDG-PET sensitivity was 88%, and accuracy in detecting peritoneal recurrence was 78%. For CT scans, sensitivity was 38% and accuracy 44% Six patients were suspected to have peritoneal recurrence based on FDG-PET and 5 were identified pathologically with peritoneal metastasis. Lesions smaller than 30 mm were not detected by CT. FDG-PET detected 15 mm lesions. In conclusion, FDG-PET is an accurate, noninvasive way to detect peritoneal recurrence in colorectal cancer and would play an important role in clinical management. (author)

  3. Magnetic resonance imaging-guided attenuation and scatter corrections in three-dimensional brain positron emission tomography

    CERN Document Server

    Zaidi, H; Slosman, D O

    2003-01-01

    Reliable attenuation correction represents an essential component of the long chain of modules required for the reconstruction of artifact-free, quantitative brain positron emission tomography (PET) images. In this work we demonstrate the proof of principle of segmented magnetic resonance imaging (MRI)-guided attenuation and scatter corrections in 3D brain PET. We have developed a method for attenuation correction based on registered T1-weighted MRI, eliminating the need of an additional transmission (TX) scan. The MR images were realigned to preliminary reconstructions of PET data using an automatic algorithm and then segmented by means of a fuzzy clustering technique which identifies tissues of significantly different density and composition. The voxels belonging to different regions were classified into air, skull, brain tissue and nasal sinuses. These voxels were then assigned theoretical tissue-dependent attenuation coefficients as reported in the ICRU 44 report followed by Gaussian smoothing and additio...

  4. In vivo evaluation of [11C]preladenant positron emission tomography for quantification of adenosine A2A receptors in the rat brain

    NARCIS (Netherlands)

    Zhou, Xiaoyun; Khanapur, Shivashankar; de Jong, Johan R; Willemsen, Antoon T.M.; Dierckx, Rudi Ajo; Elsinga, Philip H; de Vries, Erik Fj

    2016-01-01

    [(11)C]Preladenant was developed as a novel adenosine A2A receptor positron emission tomography radioligand. The present study aims to evaluate the suitability of [(11)C]preladenant positron emission tomography for the quantification of striatal A2A receptor density and the assessment of striatal A2

  5. Embedded design based virtual instrument program for positron beam automation

    Energy Technology Data Exchange (ETDEWEB)

    Jayapandian, J.; Gururaj, K.; Abhaya, S.; Parimala, J. [Material Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, TN (India); Amarendra, G. [Material Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, TN (India)], E-mail: amar@igcar.gov.in

    2008-10-31

    Automation of positron beam experiment with a single chip embedded design using a programmable system on chip (PSoC) which provides easy interfacing of the high-voltage DC power supply is reported. Virtual Instrument (VI) control program written in Visual Basic 6.0 ensures the following functions (i) adjusting of sample high voltage by interacting with the programmed PSoC hardware, (ii) control of personal computer (PC) based multi channel analyzer (MCA) card for energy spectroscopy, (iii) analysis of the obtained spectrum to extract the relevant line shape parameters, (iv) plotting of relevant parameters and (v) saving the file in the appropriate format. The present study highlights the hardware features of the PSoC hardware module as well as the control of MCA and other units through programming in Visual Basic.

  6. Embedded design based virtual instrument program for positron beam automation

    Science.gov (United States)

    Jayapandian, J.; Gururaj, K.; Abhaya, S.; Parimala, J.; Amarendra, G.

    2008-10-01

    Automation of positron beam experiment with a single chip embedded design using a programmable system on chip (PSoC) which provides easy interfacing of the high-voltage DC power supply is reported. Virtual Instrument (VI) control program written in Visual Basic 6.0 ensures the following functions (i) adjusting of sample high voltage by interacting with the programmed PSoC hardware, (ii) control of personal computer (PC) based multi channel analyzer (MCA) card for energy spectroscopy, (iii) analysis of the obtained spectrum to extract the relevant line shape parameters, (iv) plotting of relevant parameters and (v) saving the file in the appropriate format. The present study highlights the hardware features of the PSoC hardware module as well as the control of MCA and other units through programming in Visual Basic.

  7. Embedded design based virtual instrument program for positron beam automation

    International Nuclear Information System (INIS)

    Automation of positron beam experiment with a single chip embedded design using a programmable system on chip (PSoC) which provides easy interfacing of the high-voltage DC power supply is reported. Virtual Instrument (VI) control program written in Visual Basic 6.0 ensures the following functions (i) adjusting of sample high voltage by interacting with the programmed PSoC hardware, (ii) control of personal computer (PC) based multi channel analyzer (MCA) card for energy spectroscopy, (iii) analysis of the obtained spectrum to extract the relevant line shape parameters, (iv) plotting of relevant parameters and (v) saving the file in the appropriate format. The present study highlights the hardware features of the PSoC hardware module as well as the control of MCA and other units through programming in Visual Basic

  8. Positron lifetime study in dilute electron irradiated lead based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moya, G. [Lab. de Physique des Materiaux, 13 Marseille (France); Li, X.H. [D.R.F.M., S.P.2.M., M.P., C.E.N.G., 38 Grenoble (France); Menai, A. [Lab. de Physique des Materiaux, 13 Marseille (France); Kherraz, M. [Lab. de Physique des Materiaux, 13 Marseille (France); Amenzou, H. [Lab. de Physique des Materiaux, 13 Marseille (France); Bernardini, J. [Lab. de Metallurgie, 13 Marseille (France); Moser, P. [D.R.F.M., S.P.2.M., M.P., C.E.N.G., 38 Grenoble (France)

    1995-06-01

    The recovery of defects in two dilute solute-lead based alloys (Pb-Au, Pb-Cd) has been followed by positron lifetime measurements after a 3 MeV electron irradiation at 20 K. Two distinct isochronal annealing stages, the first centred at about 150 K and the other around 275 K, are to be observed as exactly the same in both the pure Pb and dilute alloys but the vacancy clustering over the second stage seen in lead and Pb-Au is completely suppressed in the Pb-Cd alloy. The results are discussed in terms of a high interaction between the cadmium atoms and vacancies in agreement with a probable presence of atomic excitons. (orig.)

  9. Positron lifetime study in dilute electron irradiated lead based alloys

    International Nuclear Information System (INIS)

    The recovery of defects in two dilute solute-lead based alloys (Pb-Au, Pb-Cd) has been followed by positron lifetime measurements after a 3 MeV electron irradiation at 20 K. Two distinct isochronal annealing stages, the first centred at about 150 K and the other around 275 K, are to be observed as exactly the same in both the pure Pb and dilute alloys but the vacancy clustering over the second stage seen in lead and Pb-Au is completely suppressed in the Pb-Cd alloy. The results are discussed in terms of a high interaction between the cadmium atoms and vacancies in agreement with a probable presence of atomic excitons. (orig.)

  10. Positron lifetime study in dilute electron irradiated lead based alloys

    International Nuclear Information System (INIS)

    The recovery of defects in two dilute solute-lead based alloys (Pb-Au, Pb-Cd) has been followed by positron lifetime measurements after a 3 MeV electron irradiation at 20 K. Two distinct isochronal annealing stages, the first centered at about 150 K and the other around 275 K, are to be observed as exactly the same in both the pure Pb and dilute alloys but the vacancy clustering over the second stage seen in lead and Pb-Au is completely suppressed in the Pb-Cd alloy. The results are discussed in terms of a high interaction between the cadmium atoms and vacancies in agreement with a probable presence of atomic excitons. (authors). 3 figs., 9 refs

  11. Minicyclotron-based technology for the production of positron-emitting labelled radiopharmaceuticals

    International Nuclear Information System (INIS)

    The use of short-lived positron emitters such as carbon 11, fluorine 18, nitrogen 13, and oxygen 15, together with positron-emission tomography (PET) for probing the dynamics of physiological and biochemical processes in the normal and diseased states in man is presently an active area of research. One of the pivotal elements for the continued growth and success of PET is the routine delivery of the desired positron emitting labelled compounds. To date, the cyclotron remains the accelerator of choice for production of medically useful radionuclides. The development of the technology to bring the use of cyclotrons to a clinical setting is discussed

  12. Evaluation of blood-brain barrier permeability changes in rhesus monkeys and man using 82Rb and positron emission tomography

    International Nuclear Information System (INIS)

    Dynamic positron tomography of the brain with /sup 82/Rb, obtained from a portable generator [/sup 82/Sr (25 days) - /sup 82/Rb (76 sec)], provides a means of studying blood-brain barrier (BBB) permeability in physiological and clinical investigations. The BBB in rhesus monkeys was opened unilaterally be intracarotid infusion of 3 M urea. This osmotic barrier opening allowed entry into the brain of intravenously administered rubidium chloride. The BBB opening was demonstrated noninvasively using /sup 82/Rb and positron emission tomography and corroborated by the accumulation of /sup 86/Rb in tissue samples. Positron emission tomography studies can be repeated every 5 min and indicate that dynamic tomography or static imaging can be used to study BBB permeability changes induced by a wide variety of noxious stimuli. Brain tumors in human subjects are readily detected because of the usual BBB permeability disruption in and around the tumors

  13. Evaluation of blood--brain barrier permeability changes in rhesus monkeys and man using 82Rb and positron emission tomography

    International Nuclear Information System (INIS)

    Dynamic positron tomography of the brain with 82Rb, obtained from a portable generator [82Sr (25 days) -- 82Rb (76 sec)], provides a means of studying blood-brain barrier (BBB) permeability in physiological and clinical investigations. The BBB in rhesus monkeys was opened unilaterally by intracarotid infusion of 3 M urea. This osmotic barrier opening allowed entry into the brain of intravenously administered rubidium chloride. The BBB opening was demonstrated noninvasively using 82Rb and positron emission tomography and corroborated by the accumulation of 86Rb in tissue samples. Positron emission tomography studies can be repeated every 5 min and indicate that dynamic tomography or static imaging can be used to study BBB permeability changes induced by a wide variety of noxious stimuli. Brain tumors in human subjects are readily detected because of the usual BBB permeability disruption in and around the tumors

  14. Use of positron emission tomography for real-time imaging of biodistribution of green tea catechin.

    Directory of Open Access Journals (Sweden)

    Kosuke Shimizu

    Full Text Available The aim of this study was to achieve real-time imaging of the in vivo behavior of a green tea polyphenol, catechin, by positron emission tomography (PET. Positron-labeled 4″ -[(11C]methyl-epigallocatechin gallate ([(11C]Me-EGCG was orally administered to rats, and its biodistribution was imaged for 60 min by using a small animal PET system. As the result, images of [(11C]Me-EGCG passing through the stomach into the small intestines were observed; and a portion of it was quantitatively detected in the liver. On the other hand, intravenous injection of [(11C]Me-EGCG resulted in a temporal accumulation of the labeled catechin in the liver, after which almost all of it was transferred to the small intestines within 60 min. In the present study, we succeeded in obtaining real-time imaging of the absorption and biodistribution of [(11C]Me-EGCG with a PET system.

  15. Positron emission tomography with [{sup 18}F]FDG for therapy response monitoring in lymphoma patients

    Energy Technology Data Exchange (ETDEWEB)

    Spaepen, Karoline; Stroobants, Sigrid; Mortelmans, Luc [Department of Nuclear Medicine, UZ Gasthuisberg, Herestraat 49, 3000, Leuven (Belgium); Verhoef, Gregor [Department of Hematology, UZ Gasthuisberg, Herestraat 49, 3000, Leuven (Belgium)

    2003-06-01

    Lymphomas are a heterogeneous group of diseases with differing histopathology, clinical behaviour, response to therapy and outcome. Lymphomas are highly sensitive to chemotherapy and radiotherapy, and the recent developments in treatment have considerably improved clinical outcome. However, there is increasing recognition that this has been at the cost of long-term treatment-related effects in a relatively young patient population. Thus, one of the most challenging aspects in the imaging of lymphoma patients is tailoring the intensity of the treatment to the individual patient. This paper reviews recently published data concerning the use of fluorine-18 fluorodeoxyglucose positron emission tomography ([{sup 18}F]FDG-PET) for therapy monitoring in lymphoma patients and highlights the shortcomings and future directions. A temporary strategy for the implementation of [{sup 18}F]FDG-PET in the management of lymphoma patients is proposed. (orig.)

  16. An 8×8 Row-Column Summing Readout Electronics for Preclinical Positron Emission Tomography Scanners.

    Science.gov (United States)

    Shih, Y C; Sun, F W; Macdonald, L R; Otis, B P; Miyaoka, R S; McDougald, W; Lewellen, T K

    2009-10-24

    This work presents a row/column summing readout electronics for an 8×8 silicon photomultiplier array. The summation circuit greatly reduces the number of electronic channels, which is desirable for pursuing higher resolution positron emission tomography scanners. By using a degenerated common source topology in the summation circuit, more fan-in is possible and therefore a greater reduction in the number of electronic channels can be achieved. The timing signal is retrieved from a common anode, which allows the use of a single fast-sampling analog to digital converter (ADC) for the timing channel and slower, lower power ADCs for the 64 spatial channels. Preliminary results of one row summation of the 8×8 readout electronics exhibited FWHM energy resolution of 17.8% and 18.3% with and without multiplexing, respectively. The measured timing resolution is 2.9ns FWHM. PMID:20729983

  17. Positron emission tomography in human hemispheric infarction: a study with 150 continuous inhalation technique

    International Nuclear Information System (INIS)

    Non-invasive tomographic imaging of cerebral blood flow and oxygen metabolism has now become possible with the 15O continuous inhalation technique coupled with positron emission tomography (PET). We have for the first time applied this procedure in a large scale study of human hemispheric infarction. From this study, it may be concluded that: various hitherto undescribed patterns of disturbances in the perfusion/metabolism couple that occur in cerebral infarction have been documented by PET imaging of CBF and EO2. The EO2 appears as an important physiological parameter in the study of recent cerebral infarction, and specific patterns of the CBF/EO2 relationship are now emerging that may have important pathophysiologic, prognostic and therapeutic implications. Despite some limitations, the non invasive 15O inhalation technique has a number of major specific advantages that make it particularly suited for the study of ischemic brain disorders

  18. Test-Retest Repeatability of Myocardial Blood Flow Measurements using Rubidium-82 Positron Emission Tomography

    Science.gov (United States)

    Efseaff, Matthew

    Rubidium-82 positron emission tomography (PET) imaging has been proposed for routine myocardial blood flow (MBF) quantification. Few studies have investigated the test-retest repeatability of this method. Same-day repeatability of rest MBF imaging was optimized with a highly automated analysis program using image-derived input functions and a dual spillover correction (SOC). The effects of heterogeneous tracer infusion profiles and subject hemodynamics on test-retest repeatability were investigated at rest and during hyperemic stress. Factors affecting rest MBF repeatability included gender, suspected coronary artery disease, and dual SOC (p stress, and 0.95 for stress / rest myocardial flow reserve (MFR). Subjects with heterogeneous tracer infusion profiles and hemodynamic conditions had significantly less repeatable MBF measurements at rest, stress, and stress/rest flow reserve (p < 0.05).

  19. Patterns of brain activity in normals and schizophrenics with positron emission tomography

    International Nuclear Information System (INIS)

    The authors investigated the functional interaction among brain areas under baseline and upon activation by a visual task to compare the response of normal subjects from the ones of chronic schizophrenics. Cerebral metabolic images were obtained on twelve healthy volunteers an eighteen schizophrenics with positron emission tomography and 11-C-Deoxyglucose. Correlation coefficients among the relative metabolic values (region of interest divided by the average of whole brain gray matter) of 11 brain regions; frontal, parietal, temporal and occipital left and right lobes, left and right basal ganglia and thalamus were computed for the baseline and for the task. Under baseline, normals showed more functional correlations than schizophrenics. Both groups showed a thalamo-occipital (positive) and thalamo-frontal (negative) interaction. The highest correlations among homologous brain areas were the frontal, occipital and basal ganglia

  20. Time sequence image analysis of positron emission tomography using wavelet transformation.

    Science.gov (United States)

    Hsu, Chih-Yu; Lai, Yeong-Lin; Chen, Chih-Cheng; Lee, Yu-Tzu; Tseng, Kuo-Kun; Lai, Yeong-Kang; Zheng, Chun-Yi; Jheng, Huai-Cian

    2015-01-01

    This paper presents the time sequence image analysis technique of positron emission tomography (PET) using a wavelet transformation method. The abdominal cavity of a person taking [18F]Fluoro-2-deoxy-2-D-glucose (18F-FDG) was scanned by the dynamic PET. The organ selection with dynamic PET images was conducted by the wavelet transformation to implement automatic selection of the region of interest (ROI). The image segmentation was carried out by the processes of sampling, wavelet transformation, erosion, dilation, and superimposition. Wavelet constructed image (WCI) contours were created by sampling 512 images from 1960 consecutive dynamic sequence PET images. The image segmentation technology developed can help doctors automatically select ROI, accurately identify lesion locations of organs, and thus effectively reduce human operation time and errors. PMID:26578275

  1. Marked reduction of cerebral oxygen metabolism in patients with advanced cirrhosis; A positron emission tomography study

    Energy Technology Data Exchange (ETDEWEB)

    Kawatoko, Toshiharu; Murai, Koichiro; Ibayashi, Setsurou; Tsuji, Hiroshi; Nomiyama, Kensuke; Sadoshima, Seizo; Eujishima, Masatoshi; Kuwabara, Yasuo; Ichiya, Yuichi (Kyushu Univ., Fukuoka (Japan). Faculty of Medicine)

    1992-01-01

    Regional cerebral blood flow (rCBF), cerebral metabolic rate of oxygen (rCMRO{sub 2}), and oxygen extraction fraction (rOEF) were measured using positron emission tomography (PET) in four patients with cirrhosis (two males and two females, aged 57 to 69 years) in comparison with those in five age matched controls with previous transient global amnesia. PET studies were carried out when the patients were fully alert and oriented after the episodes of encephalopathy. In the patients, rCBF tended to be lower, while rCMRO{sub 2} was significantly lowered in almost all hemisphere cortices, more markedly in the frontal cortex. Our results suggest that the brain oxygen metabolism is diffusely impaired in patients with advanced cirrhosis, and the frontal cortex seems to be more susceptible to the systemic metabolic derangements induced by chronic liver disease. (author).

  2. Nicotine Blocks Brain Estrogen Synthase (Aromatase): In Vivo Positron Emission Tomography Studies in Female Baboons

    International Nuclear Information System (INIS)

    Cigarette smoking and nicotine have complex effects on human physiology and behavior, including some effects similar to those elicited by inhibition of aromatase, the last enzyme in estrogen biosynthesis. We report the first in vivo primate study to determine whether there is a direct effect of nicotine administration on brain aromatase. Brain aromatase availability was examined with positron emission tomography and the selective aromatase inhibitor (11C)vorozole in six baboons before and after exposure to IV nicotine at .015 and .03 mg/kg. Nicotine administration produced significant, dose-dependent reductions in (11C)vorozole binding. The amygdala and preoptic area showed the largest reductions. Plasma levels of nicotine and its major metabolite cotinine were similar to those found in cigarette smokers. Nicotine interacts in vivo with primate brain aromatase in regions involved in mood, aggression, and sexual behavior.

  3. Dose absorbed by technologists in positron emission tomography procedures with FDG

    International Nuclear Information System (INIS)

    The objective of this work was to evaluate radiation doses delivered to technologists engaged in different tasks involving positron emission tomography (PET) studies with FDG (fluorodeoxyglucose). This investigation was performed in two French nuclear medicine departments, which presented significant differences in their arrangements and radiation safety conditions. Both centers administered about 300 MBq per PET/CT study, although only one of them is a dedicated clinical PET center. Dose equivalent Hp(10) and skin dose Hp(0.07) were measured using Siemens electronic personnel dosimeters. For assessment dose absorbed by hands during drawing up of tracer and injection into the patient, a Polimaster wristwatch gamma dosimeter was employed. Absorbed dose and the time spent during each investigated task were recorded for a total of 180 whole-body PET studies. In this report, the methodology employed, the results and their radioprotection issues are presented as well as discussed. (author)

  4. An Application of Micro-channel Plate Photomultiplier Tube to Positron Emission Tomography.

    Science.gov (United States)

    Kim, H; Chen, C-T; Frisch, H; Tang, F; Kao, C-M

    2012-01-01

    We are developing a Time-of-Flight Positron Emission Tomography detector using flat panel micro-channel plate photomultiplier tubes (MCP PMT). The high-speed waveform sampling data acquisition is adopted to exploit the fast time response of MCP PMT efficiently by using transmission-line readout scheme. To demonstrate the feasibility of the proposed detector, prototype detector modules were built using Photonis XP85022 MCP PMT, transmission-line board (TL), and high-speed waveform sampling electronics equipped with DRS4 chips. The MCP/TL module was coupled to single LYSO crystal, and experimental tests have been conducted in a coincidence setup to measure the responses to 511 keV annihilation photon. The details of the prototype module, experimental setup, and the preliminary results are presented and discussed. PMID:23227135

  5. Nicotine Blocks Brain Estrogen Synthase (Aromatase): In Vivo Positron Emission Tomography Studies in Female Baboons

    Energy Technology Data Exchange (ETDEWEB)

    Biegon, A.; Biegon, A.; Kim, S.-W.; Logan, J.; Hooker, J.M.; Muench, L.; Fowler, J.S.

    2010-01-12

    Cigarette smoking and nicotine have complex effects on human physiology and behavior, including some effects similar to those elicited by inhibition of aromatase, the last enzyme in estrogen biosynthesis. We report the first in vivo primate study to determine whether there is a direct effect of nicotine administration on brain aromatase. Brain aromatase availability was examined with positron emission tomography and the selective aromatase inhibitor [{sup 11}C]vorozole in six baboons before and after exposure to IV nicotine at .015 and .03 mg/kg. Nicotine administration produced significant, dose-dependent reductions in [{sup 11}C]vorozole binding. The amygdala and preoptic area showed the largest reductions. Plasma levels of nicotine and its major metabolite cotinine were similar to those found in cigarette smokers. Nicotine interacts in vivo with primate brain aromatase in regions involved in mood, aggression, and sexual behavior.

  6. Experience with carbon-11 choline positron emission tomography in prostate carcinoma

    International Nuclear Information System (INIS)

    We investigated the potential of carbon-11 choline positron emission tomography (PET) for the detection of lymph node and bone metastases in prostate cancer. A total of 23 patients were studied (known metastases: 8; suspicion of metastases: 3; primary staging: 12). Whole-body PET imaging was performed 5 min after injection of the tracer and completed within 1 h. Focally increased tracer uptake in bone or abdominal lymph node regions was interpreted as representing tumour involvement. All known bone and lymph node metastases could be recognized by [11C]choline PET. One out of ten negative scans for primary staging was false-negative (lymph node 11C]choline PET is a promising new tool for the primary staging of prostate cancer, with lymph node and bone metastases demonstrating high tracer uptake. Therapeutic management could be influenced by these results in that the technique may permit avoidance of surgical lymph node exploration. (orig.)

  7. Drug washout issues in studies of cerebral metabolism by positron emission tomography in psychiatric patients

    International Nuclear Information System (INIS)

    Many studies of brain glucose utilization by positron emission tomography attempt to describe the modifications of the brain activity during psychiatric diseases. A major difficulty in such studies is the necessity to assess patients free of pharmacological treatment, in order to relate the measured changes in glucose utilization to the pathopsychology, and not to a drug effect. In this paper are reviewed the arguments from the literature allowing to estimate the drug washout time for considering the patients as drug-free. The review is focussed on the known effects of the psychotrops on brain glucose utilization. This time is approximately six months for the neuroleptics given orally, one month for antidepressants, and five and a half half-lives for benzodiazepines. Alternative research strategies for avoiding a long drug washout are mentioned, and ethical limitations are considered. (author)

  8. Usefulness of positron emission tomography (TEP) in the assessment of osteo-articular prosthesis

    International Nuclear Information System (INIS)

    Joint arthroplasty is performed with increasing frequency as the population ages. Loosening or infection of the prosthesis is a relatively common event that can limit the lifetime of a prosthesis. Accuracy differentiation between aseptic and septic loosening of the prosthesis remains a challenge because of the consequences for patient management. Moreover, an early diagnosis of infected hip prosthesis is very important for optimal and cost-effective management. Various approaches have developed to visualize infection and inflammation by nuclear medicine techniques. Recently positron emission tomography (PET) with fluorine-l8 labelled 2 fluoro-2-deoxyglucose (18F-FDG) has been shown to delineate infectious and inflammatory foci with high sensitivity owing to the increased glucose metabolism in inflammatory cells. In this paper we review the role of FDG-PET in this common differential diagnosis in patients with total knee and hip prostheses. Different patterns of FDG-PET interpretation have been described as wed as methodological aspects. (author)

  9. Kinetic filtering of [18F]Fluorothymidine in positron emission tomography studies

    International Nuclear Information System (INIS)

    [18F]Fluorothymidine (FLT) is a cell proliferation marker that undergoes predominantly hepatic metabolism and therefore shows a high level of accumulation in the liver, as well as in rapidly proliferating tumours. Furthermore, the tracer's uptake is substantial in other organs including the heart. We present a nonlinear kinetic filtering technique which enhances the visualization of tumours imaged with FLT positron emission tomography (FLT-PET). A classification algorithm to isolate cancerous tissue from healthy organs was developed and validated using 29 scan data from patients with locally advanced or metastatic breast cancer. A large reduction in signal from the liver and heart of 80% was observed following application of the kinetic filter, whilst the majority of signal from both primary tumours and metastases was retained. A scan acquisition time of 60 min has been shown to be sufficient to obtain the necessary kinetic data. The algorithm extends utility of FLT-PET imaging in oncology research.

  10. Post-traumatic diaphragmatic herniation of the liver, examined by positron emission tomography: case report

    Directory of Open Access Journals (Sweden)

    Chatani Naru

    2011-08-01

    Full Text Available Abstract We present a case of post-traumatic diaphragmatic herniation of the liver, which mimicked an intrathoracic tumor. After an automobile accident, the patient underwent thoracotomies for hemothorax and lung cancer in the right chest. Seven months later, computed tomography (CT demonstrated a round tumor in the thorax adjacent to the right diaphragm with a higher density than the liver parenchyma. An intrathoracic tumor including a primary or metastatic lung cancer was suspected. However, positron emission tomography (PET showed that the uptake of fluorine-18-fluorodeoxyglucose (FDG was identical to that in the liver, and the tumor appeared to be contiguous with the liver. Thus, we suspected liver herniation. Core needle biopsy revealed liver cells without neoplastic tissue. Upon surgical exploration, herniation of the liver was found and repaired. PET was helpful in providing morphological and functional information leading to accurate diagnosis of liver herniation in this unusual case.

  11. Clinical use of amyloid-positron emission tomography neuroimaging: Practical and bioethical considerations.

    Science.gov (United States)

    Witte, Michael M; Foster, Norman L; Fleisher, Adam S; Williams, Monique M; Quaid, Kimberly; Wasserman, Michael; Hunt, Gail; Roberts, J Scott; Rabinovici, Gil D; Levenson, James L; Hake, Ann Marie; Hunter, Craig A; Van Campen, Luann E; Pontecorvo, Michael J; Hochstetler, Helen M; Tabas, Linda B; Trzepacz, Paula T

    2015-09-01

    Until recently, estimation of β-amyloid plaque density as a key element for identifying Alzheimer's disease (AD) pathology as the cause of cognitive impairment was only possible at autopsy. Now with amyloid-positron emission tomography (amyloid-PET) neuroimaging, this AD hallmark can be detected antemortem. Practitioners and patients need to better understand potential diagnostic benefits and limitations of amyloid-PET and the complex practical, ethical, and social implications surrounding this new technology. To complement the practical considerations, Eli Lilly and Company sponsored a Bioethics Advisory Board to discuss ethical issues that might arise from clinical use of amyloid-PET neuroimaging with patients being evaluated for causes of cognitive decline. To best address the multifaceted issues associated with amyloid-PET neuroimaging, we recommend this technology be used only by experienced imaging and treating physicians in appropriately selected patients and only in the context of a comprehensive clinical evaluation with adequate explanations before and after the scan. PMID:27239516

  12. [18F]-labeled 2-methoxyphenylpiperazine derivative as a potential brain positron emission tomography imaging agent

    International Nuclear Information System (INIS)

    This study reports the synthesis and characterization of N-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl-4-[18F]fluorobenzamide ([18F]MPP3F). The total reaction time for [18F]MPP3F, including final high-performance liquid chromatography purification, was about 3 h. Typical decay-corrected radiochemical yield was 18.4±3.1%. The radiochemical purity was >98%. Biodistribution in mice showed that [18F]MPP3F is a potential brain imaging agent for positron emission tomography. The brain uptake of [18F]MPP3F was 6.59±0.77% Injected Dose/g at 2 min post-injection time. A brain-to-blood ratio of 3.67 was reached at 15 min after injection.

  13. Synthesis of fluorine-18-labelled TSPO ligands for imaging neuro inflammation with Positron Emission Tomography

    International Nuclear Information System (INIS)

    Fluorine-18 radiochemistry is an essential tool in Positron Emission Tomography, providing the bridge between the cyclotron-produced raw radioisotope and the biomedical image of an in vivo radioactivity distribution. From the fluorine-18 labelled radioligands for the translocator protein 18 kDa that are produced in our laboratory, namely [18F]FEDAA1106, 6-[18F]F-PBR28, [18F]PBR111 and [18F]DPA-714, we address various aspects of fluorine-18 radiochemistry, such as rationales of radiotracer design, radioisotope production and [18F]fluoride activation, and procedures of radio-fluorination, purification and formulation. Automation of the radiochemistry process has become indispensable in order to assure a constant radiopharmaceutical quality and reproducible radiochemical yields as well as to meet the required radiation protection aspects. (authors)

  14. Hemiballismus: Study of a case using positron emission tomography with 18fluoro-2-deoxyglucose

    International Nuclear Information System (INIS)

    A 64-year-old man had right-sided persistent hemiballismus. Cerebral computed tomography (CT) and 0.5-T magnetic resonance imaging (MRI) showed no abnormalities, but 1.5-T MRI showed decreased signal intensity of the putamina, greater on the left than on the right. The subthalamic area was normal on CT and MRI. Positron emission tomography with 18fluoro2-deoxyglucose showed marked hypometabolism of the left putamen (60% of the right) and hypermetabolism of the left parietal lobe (138% of the right). The decreased metabolism of the left putamen may indicate a reduction in neuronal firing. The pathophysiology of the hemiballismus in this case may be loss of tonic inhibition of the lateral globus pallidus from the putamen, leading in turn to greater inhibition of the subthalamic nucleus, less excitation of the medial globus pallidus, and less inhibition of the thalamus and motor cortex, and thus allowing expression of the ballistic movements

  15. Design And Development Of A Mammary And Axillary Region Positron Emission Tomography System (maxpet)

    CERN Document Server

    Doshi, N K

    2000-01-01

    Breast cancer is the second leading cause of cancer death in women. Currently, mammography and physical breast examination, both non-invasive techniques, provide the two most effective methods available for screening potential breast cancer patients. During the management of patients, however, several invasive techniques such as axillary lymph node dissection, core biopsies and lumpectomies, are utilized to determine the stage or malignancy of the disease with significant cost and morbidity associated with them. Positron Emission Tomography (PET), using [F-18] fluorodeoxyglucose (FDG) tracer is a sensitive and non-invasive imaging modality that may be a cost-effective alternative to certain invasive procedures. In this project we have developed a low cost, high performance, dedicated PET camera (maxPET) for mammary and axillary region imaging. The system consists of two 15x15 cm2 planar scintillation detector arrays composed of modular detectors operating in coincidence. The modular detectors are comprised of...

  16. Greater left cerebral hemispheric metabolism in bulimia assessed by positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.C.; Hagman, J.; Buchsbaum, M.S.; Blinder, B.; Derrfler, M.; Tai, W.Y.; Hazlett, E.; Sicotte, N. (Univ. of California, Irvine (USA))

    1990-03-01

    Eight women with bulimia and eight age- and sex-matched normal control subjects were studied with positron emission tomography using (18F)-fluorodeoxyglucose (FDG) as a tracer of brain metabolic rate. Subjects performed a visual vigilance task during FDG uptake. In control subjects, the metabolic rate was higher in the right hemisphere than in the left, but patients with bulimia did not have this normal asymmetry. Lower metabolic rates in the basal ganglia, found in studies of depressed subjects, and higher rates in the basal ganglia, reported in a study of anorexia nervosa, were not found. This is consistent with the suggestion that bulimia is a diagnostic grouping distinct from these disorders.

  17. Speech processing system demonstrated by positron emission tomography (PET). A review of the literature

    International Nuclear Information System (INIS)

    We review the literature on speech processing in the central nervous system as demonstrated by positron emission tomography (PET). Activation study using PET has been proved to be a useful and non-invasive method of investigating the speech processing system in normal subjects. In speech recognition, the auditory association areas and lexico-semantic areas called Wernicke's area play important roles. Broca's area, motor areas, supplementary motor cortices and the prefrontal area have been proved to be related to speech output. Visual speech stimulation activates not only the visual association areas but also the temporal region and prefrontal area, especially in lexico-semantic processing. Higher level speech processing, such as conversation which includes auditory processing, vocalization and thinking, activates broad areas in both hemispheres. This paper also discusses problems to be resolved in the future. (author) 42 refs

  18. Image properties of list mode likelihood reconstruction for a rectangular positron emission mammography with DOI measurements

    International Nuclear Information System (INIS)

    A positron emission mammography scanner is under development at our Laboratory. The tomograph has a rectangular geometry consisting of four banks of detector modules. For each detector, the system can measure the depth of interaction information inside the crystal. The rectangular geometry leads to irregular radial and angular sampling and spatially variant sensitivity that are different from conventional PET systems. Therefore, it is of importance to study the image properties of the reconstructions. We adapted the theoretical analysis that we had developed for conventional PET systems to the list mode likelihood reconstruction for this tomograph. The local impulse response and covariance of the reconstruction can be easily computed using FFT. These theoretical results are also used with computer observer models to compute the signal-to-noise ratio for lesion detection. The analysis reveals the spatially variant resolution and noise properties of the list mode likelihood reconstruction. The theoretical predictions are in good agreement with Monte Carlo results

  19. EndoTOFPET-US a Novel Multimodal Tool for Endoscopy and Positron Emission Tomography

    CERN Document Server

    Garutti, Erika

    2013-01-01

    The EndoTOFPET-US project aims to jointly exploit Time-Of-Flight Positron Emission Tomography (TOFPET) and ultrasound endoscopy with a multi-modal instrument for the development of new biomarkers for pancreas and prostate oncology. The paper outlines the functionality of the proposed instrument and the challenges for its realization. The high level of miniaturization and integration poses strong demands to the fields of scintillating crystallography, ultra-fast photon detection, highly integrated electronics and system integration. Solutions are presented to obtain a coincidence time resolution better than 200 ps and a spatial resolution of ~1 mm with an asymmetric TOFPET detector. A tracking system with better than 1 mm spatial resolution precision enables the online alignment of the system. The detector design, the production and test status of the single detector

  20. The nuclear physician's point of view: positron emission tomography in research activities: how? why?

    International Nuclear Information System (INIS)

    Positron Emission Tomography (PET) constitutes a non-traumatic, dynamic and quantitative functional imaging method, particularly adapted for biological and medical investigations. Various topics can be investigated by PET, such as animal models of human pathologies, physiopathological processes, therapeutic and diagnostic strategies. The number and variety of questions for which PET can provide answers depends on the development and adaptation of tools offered by PET research centres and especially depends on the variety of available radiopharmaceutical agents. To answer researchers' questions, these centres should be equipped with dedicated and functional imaging platforms, as well as having a defined development policy. The objectives of this policy should be agreed by consensus by a multidisciplinary team under the leadership of medical and biological researchers. (author)

  1. Short time bacterial endotoxins test for positron emission tomography by means of positively charged filters

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) radiotracers have very short physical half-lives. It is hard to complete a bacterial endotoxins test prior to release from medical institutes. For endotoxin quantitative determination, limulus amebocyte lysate (LAL) reagent and kinetic-turbidimetry system were previously developed. We investigated the possibility of a short time test by means of positively charged filters. As a result of this study, the effects of positively charged filters on endotoxin removal were over 99.5% for [18F]FDG and [18F]NaF, which were contaminated with the indicated concentration of endotoxin. Combining this filter and the kinetic-turbidimetric method, it was possible to complete a bacterial endotoxins test in 5 min prior to the patient's administration. This test should be required prior to release for PET radiopharmaceutical quality control. It has been suggested that this combination is a good method for this purpose. (author)

  2. Sparse representation and dictionary learning penalized image reconstruction for positron emission tomography

    International Nuclear Information System (INIS)

    Accurate and robust reconstruction of the radioactivity concentration is of great importance in positron emission tomography (PET) imaging. Given the Poisson nature of photo-counting measurements, we present a reconstruction framework that integrates sparsity penalty on a dictionary into a maximum likelihood estimator. Patch-sparsity on a dictionary provides the regularization for our effort, and iterative procedures are used to solve the maximum likelihood function formulated on Poisson statistics. Specifically, in our formulation, a dictionary could be trained on CT images, to provide intrinsic anatomical structures for the reconstructed images, or adaptively learned from the noisy measurements of PET. Accuracy of the strategy with very promising application results from Monte-Carlo simulations, and real data are demonstrated. (paper)

  3. Interstitial brachytherapy for liver metastases and assessment of response by positron emission tomography: a case report

    Directory of Open Access Journals (Sweden)

    Goura Kishor Rath

    2010-10-01

    Full Text Available For liver metastases (LM, image guided percutaneous ablative procedures such as radiofrequency ablation (RFA, laser induced thermal therapy (LITT and trans-arterial chemo-embolisation (TACE are increasingly being used because they are relatively safer, less invasive and equally effective. CT scan guided interstitial brachytherapy (IBT with a single large dose of radiation by high dose rate (HDR brachytherapy is a novel technique of treating LM and has shown good results. Positron emission tomography (PET scan may provide better information for assessing the response toIBT procedures. We hereby report a case of LM that was treated by HDR IBT and PET scan was done in addition to CT scan for assessing the response.

  4. Caffeine and human cerebral blood flow: A positron emission tomography study

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, O.G.; Modell, J.G.; Hariharan, M. (Univ. of Michigan Medical Center, Ann Arbor (USA))

    1990-01-01

    Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decreased p{sub a}CO{sub 2} and increased systolic blood pressure significantly; the change in p{sub a}CO{sub 2} did not account for the change in CBF. Smaller increases in diastolic blood pressure, heart rate, plasma epinephrine and norepinephrine, and subjectively reported anxiety were also observed.

  5. Evaluation of regional myocardial blood flow and energy metabolism using positron emission tomography

    International Nuclear Information System (INIS)

    Regional myocardial blood flow was assessed using positron emission tomography (PET) with 13NH3; and myocardial glucose metabolism was assessed using PET with 18F-2-fluoro-2-deoxyglucose (18FDG). In patients with myocardial infarction, stress PET showed decreased blood flow in the infarcts and increased accumulation of 18FDG in part of the infarcted area, suggesting the existence of viable myocardial cells. Stress PET after AC bypass surgery showed no decreased blood flow and improvement in the uptake of 18FDG. This suggested the improvement of myocardial ischemia along with the improvement of cardiac function. PET with 13NH3 and 18FDG is of great value in evaluating the degree and pathophysiologic state of myocardial ischemia from aspects of not only blood flow but also energy metabolism. (Namekawa, K.)

  6. Imaging prostate cancer: an update on positron emission tomography and magnetic resonance imaging

    DEFF Research Database (Denmark)

    Bouchelouche, Kirsten; Turkbey, Baris; Choyke, Peter;

    2010-01-01

    molecular imaging information. Developments in imaging technologies, specifically magnetic resonance imaging (MRI) and positron emission tomography (PET)/computed tomography (CT), have improved the detection rate of prostate cancer. MRI has improved lesion detection and local staging. Furthermore, MRI......Prostate cancer is a common cancer in men and continues to be a major health problem. Imaging plays an essential role in the clinical management of patients. An important goal for prostate cancer imaging is more accurate disease characterization through the synthesis of anatomic, functional, and....../CT imaging of prostate cancer. Among these, choline (labeled with (18)F or (11)C), (11)C-acetate, and (18)F-fluoride have demonstrated promising results, and other new radiopharmaceuticals are currently under evaluation in preclinical and clinical studies....

  7. Imaging Atherosclerosis with Hybrid Positron Emission Tomography/Magnetic Resonance Imaging

    DEFF Research Database (Denmark)

    Ripa, Rasmus Sejersten; Kjær, Andreas

    2015-01-01

    Noninvasive imaging of atherosclerosis could potentially move patient management towards individualized triage, treatment, and followup. The newly introduced combined positron emission tomography (PET) and magnetic resonance imaging (MRI) system could emerge as a key player in this context. Both...... PET and MRI have previously been used for imaging plaque morphology and function: however, the combination of the two methods may offer new synergistic opportunities. Here, we will give a short summary of current relevant clinical applications of PET and MRI in the setting of atherosclerosis....... Additionally, our initial experiences with simultaneous PET/MRI for atherosclerosis imaging are presented. Finally, future potential vascular applications exploiting the unique combination of PET and MRI will be discussed....

  8. Regional cerebral glucose metabolic rate in human sleep assessed by positron emission tomography

    International Nuclear Information System (INIS)

    The cerebral metabolic rate of glucose was measured during nighttime sleep in 36 normal volunteers using positron emission tomography and fluorine-18-labeled 2-deoxyglucose (FDG). In comparison to waking controls, subjects given FDG during non-rapid eye movement (NREM) sleep showed about a 23% reduction in metabolic rate across the entire brain. This decrease was greater for the frontal than temporal or occipital lobes, and greater for basal ganglia and thalamus than cortex. Subjects in rapid eye movement (REM) sleep tended to have higher cortical metabolic rates than walking subjects. The cingulate gyrus was the only cortical structure to show a significant increase in glucose metabolic rate in REM sleep in comparison to waking. The basal ganglia were relatively more active on the right in REM sleep and symmetrical in NREM sleep

  9. Regional cerebral glucose metabolic rate in human sleep assessed by positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Buchsbaum, M.S.; Wu, J.; Hazlett, E.; Sicotte, N.; Bunney, W.E. Jr. (Univ. of California, Irvine (USA)); Gillin, J.C. (Univ. of California, San Diego (USA))

    1989-01-01

    The cerebral metabolic rate of glucose was measured during nighttime sleep in 36 normal volunteers using positron emission tomography and fluorine-18-labeled 2-deoxyglucose (FDG). In comparison to waking controls, subjects given FDG during non-rapid eye movement (NREM) sleep showed about a 23% reduction in metabolic rate across the entire brain. This decrease was greater for the frontal than temporal or occipital lobes, and greater for basal ganglia and thalamus than cortex. Subjects in rapid eye movement (REM) sleep tended to have higher cortical metabolic rates than walking subjects. The cingulate gyrus was the only cortical structure to show a significant increase in glucose metabolic rate in REM sleep in comparison to waking. The basal ganglia were relatively more active on the right in REM sleep and symmetrical in NREM sleep.

  10. Imaging prostate cancer: an update on positron emission tomography and magnetic resonance imaging

    DEFF Research Database (Denmark)

    Bouchelouche, Kirsten; Turkbey, Baris; Choyke, Peter;

    2010-01-01

    Prostate cancer is a common cancer in men and continues to be a major health problem. Imaging plays an essential role in the clinical management of patients. An important goal for prostate cancer imaging is more accurate disease characterization through the synthesis of anatomic, functional, and...... molecular imaging information. Developments in imaging technologies, specifically magnetic resonance imaging (MRI) and positron emission tomography (PET)/computed tomography (CT), have improved the detection rate of prostate cancer. MRI has improved lesion detection and local staging. Furthermore, MRI....../CT imaging of prostate cancer. Among these, choline (labeled with (18)F or (11)C), (11)C-acetate, and (18)F-fluoride have demonstrated promising results, and other new radiopharmaceuticals are currently under evaluation in preclinical and clinical studies....

  11. Unusual case of infantile fibrosarcoma evaluated on F-18 fluorodeoxyglucose positron emission tomography-computed tomography.

    Science.gov (United States)

    Bedmutha, Akshay; Singh, Natasha; Shivdasani, Divya; Gupta, Nitin

    2016-01-01

    Infantile fibrosarcoma (IFS) is a rare soft-tissue sarcoma originating from extremities and occasionally from axial soft tissue. The prognosis is good with favorable long-term survival. It is rarely metastasizing tumor, the chances being lesser with IFS originating from extremities. Use of neoadjuvant chemotherapy (NACT) as a treatment regime further reduces the chances of local relapse and distant metastasis. The organs commonly affected in metastatic IFS are lungs and lymph nodes. We report an unusual case of an IFS originating from extremity, which received NACT, yet presented with an early metastatic disease involving soft tissues and sparing lungs and lymph nodes, as demonstrated on fluorodeoxyglucose positron emission tomography-computed tomography. PMID:27385891

  12. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography in the detection of primary pulmonary angiosarcomas

    International Nuclear Information System (INIS)

    Angiosarcoma is a malignant vascular tumor that originates from the mesenchymal cells which have undergone angioblastic differentiation. Pulmonary angiosarcomas are invariably (>90%) metastatic tumors form primaries of the skin, bone, liver, breast, or heart. Primary pulmonary angiosarcomas are exceedingly rare, with just about 20 cases being reported in the literature. We report an additional case with a brief review of the literature of a primary pulmonary angiosarcoma in a 26-year-old lady who presented with intractable hemoptysis. In addition, we highlight the potential of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography as an important diagnostic tool in the evaluation of this tumor and thus contribute to the existing sparse literature on this fascinating yet devastating disease

  13. Positron emission tomography/computed tomography in the diagnosis of inflammatory processes

    International Nuclear Information System (INIS)

    The hybrid imaging modality known as PET/CT is being continuously introduced as a method of choice in the diagnostics of numerous inflammatory processes. The dual - computer tomography/positron emission tomography -investigation has advantages over other imaging modalities, mainly because of its ability to provide both morphological and functional information - combined in a whole body scan. Most of the inflammatory processes require on-time, accurate diagnostics and an imaging method that can provide therapy monitoring. The purpose of the following literature review is to compare the clinical application of PET/CT to other imaging modalities investigating inflammatory processes and to show its important role in the diagnostic algorithm and follow up of many inflammatory processes such as fever of unknown origin, osteomyelitis, inflammation of vascular prostheses etc. (authors) Key words: 18F-FDG PET/CT. DIAGNOSTIC IMAGING. INFLAMMATORY DISEASES

  14. An objective evaluation framework for segmentation techniques of functional positron emission tomography studies

    CERN Document Server

    Kim, J; Eberl, S; Feng, D

    2004-01-01

    Segmentation of multi-dimensional functional positron emission tomography (PET) studies into regions of interest (ROI) exhibiting similar temporal behavior is useful in diagnosis and evaluation of neurological images. Quantitative evaluation plays a crucial role in measuring the segmentation algorithm's performance. Due to the lack of "ground truth" available for evaluating segmentation of clinical images, automated segmentation results are usually compared with manual delineation of structures which is, however, subjective, and is difficult to perform. Alternatively, segmentation of co-registered anatomical images such as magnetic resonance imaging (MRI) can be used as the ground truth to the PET segmentation. However, this is limited to PET studies which have corresponding MRI. In this study, we introduce a framework for the objective and quantitative evaluation of functional PET study segmentation without the need for manual delineation or registration to anatomical images of the patient. The segmentation ...

  15. Integration of Quantitative Positron Emission Tomography Absolute Myocardial Blood Flow Measurements in the Clinical Management of Coronary Artery Disease.

    Science.gov (United States)

    Gewirtz, Henry; Dilsizian, Vasken

    2016-05-31

    In the >40 years since planar myocardial imaging with(43)K-potassium was introduced into clinical research and management of patients with coronary artery disease (CAD), diagnosis and treatment have undergone profound scientific and technological changes. One such innovation is the current state-of-the-art hardware and software for positron emission tomography myocardial perfusion imaging, which has advanced it from a strictly research-oriented modality to a clinically valuable tool. This review traces the evolving role of quantitative positron emission tomography measurements of myocardial blood flow in the evaluation and management of patients with CAD. It presents methodology, currently or soon to be available, that offers a paradigm shift in CAD management. Heretofore, radionuclide myocardial perfusion imaging has been primarily qualitative or at best semiquantitative in nature, assessing regional perfusion in relative terms. Thus, unlike so many facets of modern cardiovascular practice and CAD management, which depend, for example, on absolute values of key parameters such as arterial and left ventricular pressures, serum lipoprotein, and other biomarker levels, the absolute levels of rest and maximal myocardial blood flow have yet to be incorporated into routine clinical practice even in most positron emission tomography centers where the potential to do so exists. Accordingly, this review focuses on potential value added for improving clinical CAD practice by measuring the absolute level of rest and maximal myocardial blood flow. Physiological principles and imaging fundamentals necessary to understand how positron emission tomography makes robust, quantitative measurements of myocardial blood flow possible are highlighted. PMID:27245647

  16. Poor Uptake of Fluorodeoxyglucose in Positron Emission Tomography-Computed Tomography Scan for Intraocular Choroidal Melanoma in Asian Indian Eyes

    OpenAIRE

    Sharma, Rahul S.; Parag K Shah; Narendran, Venkatapathy

    2016-01-01

    Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) scan is fast becoming a very useful tool in diagnosing and staging of several malignancies that affect the human body. We report three cases of ocular choroidal malignant melanoma, wherein FDG PET-CT scan did not show as good uptake as seen in other cancers.

  17. Positron emission tomography in Huntington's chorea using C15O2, 15O2 and 18 FDG

    International Nuclear Information System (INIS)

    Positron emission tomography (PET) using C15 O2, 15O2 and 18FDG was performed in a father and his son with Huntington's chorea. It was suggested that striatal atrophy occurred before the extensive atrophy of the cerebral cortex and that the progression of atrophy of the right and left cerebral hemispheric cortexes was not uniform. (Namekawa, K.)

  18. F-18 fluoro-d-glucose positron emission tomography/computed tomography in a patient with corticobasal degeneration

    OpenAIRE

    Marti, Alejandro

    2015-01-01

    Corticobasal degeneration is a rare neurodegenerative disorder that often eludes clinical diagnosis. The present case shows the F-18 fluoro-d-glucose positron emission tomography/computed tomography (PET/CT) of a 62-year-old man with a progressive movement disorder with asymmetric features. PET/CT examination showed a markedly right-brain hemispheric hypometabolism also involving basal ganglia.

  19. 18F-Fluoride bone positron emission tomography demonstrating changes related to finger clubbing and hypertrophic osteoarthropathy

    International Nuclear Information System (INIS)

    Hypertrophic pulmonary osteoarthropathy is manifested by clubbing and periostitis of bones. We present a very rare documentation of increased F18-sodium fluoride uptake in the distal phalanges of both hands correlating to clubbing of the fingers in a 55-year-old female patient with carcinoma of lung in whom bone positron emission tomography was performed for metastatic work-up

  20. F-18 fluoro-d-glucose positron emission tomography/computed tomography in a patient with corticobasal degeneration

    International Nuclear Information System (INIS)

    Corticobasal degeneration is a rare neurodegenerative disorder that often eludes clinical diagnosis. The present case shows the F-18 fluoro-d-glucose positron emission tomography/computed tomography (PET/CT) of a 62-year-old man with a progressive movement disorder with asymmetric features. PET/CT examination showed a markedly right-brain hemispheric hypometabolism also involving basal ganglia

  1. Marked uptake of fluorodeoxyglucose in a vocal cord after medialization: Acute and subacute positron emission tomography/computed tomography findings

    International Nuclear Information System (INIS)

    A 60-year-old male who underwent left upper lobectomy because of recently diagnosed lung cancer was admitted to the nuclear medicine department. A whole body fluorodeoxyglucose positron emission tomography/computed tomography (CT) that was performed for staging purposes, revealed an intense hypermetabolism in left vocal cord region corresponding with hyperdense mass-like material on CT scan

  2. Report of two cases of fluorodeoxyglucose positron emission tomography/computed tomography appearance of hibernoma: A rare benign tumor

    International Nuclear Information System (INIS)

    False-positive findings are commonly seen in positron emission tomography computed tomography imaging. One of the most common false positive finding is uptake of fluorodeoxyglucose in brown adipose tissue. Herein, we report two cases with incidentally detected hibernomas-a brown fat containing tumor with metabolic activity

  3. Regional myocardial oxygen consumption estimated by carbon-11 acetate and positron emission tomography before and after repetitive ischemia

    DEFF Research Database (Denmark)

    Kofoed, K F; Hansen, P R; Holm, S;

    2011-01-01

    Preserved myocardial oxygen consumption estimated by carbon 11-acetate and positron emission tomography (PET) in myocardial regions with chronic but reversibly depressed contractile function in patients with ischemic heart disease have been suggested to be caused by repeated short episodes of acute...

  4. Positron emission tomography/computed tomography predictors of overall survival in stage IIIC/IV ovarian cancer

    DEFF Research Database (Denmark)

    Risum, Signe; Loft, Annika; Engelholm, Svend Aage;

    2012-01-01

    To evaluate the role of 2-deoxy-2-(F)fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) for selecting patients with extensive ovarian cancer (OC) for neoadjuvant chemotherapy by evaluating predictors of overall survival in patients with stage IIIC/IV OC....

  5. In Vivo Treatment Sensitivity Testing With Positron Emission Tomography/Computed Tomography After One Cycle of Chemotherapy for Hodgkin Lymphoma

    DEFF Research Database (Denmark)

    Hutchings, Martin; Kostakoglu, Lale; Zaucha, Jan Maciej;

    2014-01-01

    PURPOSE: Negative [(18)F]fluorodeoxyglucose (FDG) -positron emission tomography (PET)/computed tomography (CT) after two cycles of chemotherapy indicates a favorable prognosis in Hodgkin lymphoma (HL). We hypothesized that the negative predictive value would be even higher in patients responding...

  6. The prognostic value of positron emission tomography in non-small cell lung cancer : Analysis of 266 cases

    NARCIS (Netherlands)

    Kramer, H.; Post, W.J.; Pruim, J.; Groen, H.J.M.

    2006-01-01

    Positron emission tomography (PET) is more accurate than computed tomography (CT) in the staging of non-small cell lung cancer (NSCLC). We analyzed the prognostic value of PET for survival in NSCLC patients. Methods: Consecutive patients with proven NSCLC with PET for staging were selected. Staging

  7. Demonstration of decreased functional activity of visual cortex by [11C]methylglucose and positron emission tomography

    International Nuclear Information System (INIS)

    A hemorrhagic infarction which caused left hemiparesis and homonymous hemianopia was demonstrated as a hypodense lesion on the first CT; 2 weeks later it was hyperdense and enhanced after injecting meglumine. Positron emission tomography with [11C]methyl-D-glucose also revealed the ischemic lesion, but also marked decrease of glucose uptake in the visual cortex, which indicated decreased functional activity. (orig.)

  8. 18F-Fluoride bone positron emission tomography demonstrating changes related to finger clubbing and hypertrophic osteoarthropathy

    OpenAIRE

    Kashyap, Raghava; Ali, Mirza Athar; Nagaraju, Madhusudhan; Muntimadugu, Babaiah

    2014-01-01

    Hypertrophic pulmonary osteoarthropathy is manifested by clubbing and periostitis of bones. We present a very rare documentation of increased F18-sodium fluoride uptake in the distal phalanges of both hands correlating to clubbing of the fingers in a 55-year-old female patient with carcinoma of lung in whom bone positron emission tomography was performed for metastatic work-up.

  9. 18F-Fluoride bone positron emission tomography demonstrating changes related to finger clubbing and hypertrophic osteoarthropathy.

    Science.gov (United States)

    Kashyap, Raghava; Ali, Mirza Athar; Nagaraju, Madhusudhan; Muntimadugu, Babaiah

    2014-04-01

    Hypertrophic pulmonary osteoarthropathy is manifested by clubbing and periostitis of bones. We present a very rare documentation of increased F18-sodium fluoride uptake in the distal phalanges of both hands correlating to clubbing of the fingers in a 55-year-old female patient with carcinoma of lung in whom bone positron emission tomography was performed for metastatic work-up. PMID:24761070

  10. Kinetic modeling of Fe-52/Mn-52m-citrate at the blood-brain barrier by positron emission tomography

    NARCIS (Netherlands)

    Calonder, C; Wurtenberger, PI; Maguire, RP; Pellikka, R; Leenders, KL

    1999-01-01

    The kinetics of iron at the blood-brain barrier of the monkey were studied in vivo using positron emission tomography (PET) and the tracer Fe-52/Mn-52m-citrate. Mn-52m is the beta(+)-emitting daughter nuclide of Fe-52 and therefore contributes to the observed signal and background in the PET images

  11. Unusual sites of metastatic recurrence of osteosarcoma detected on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography

    International Nuclear Information System (INIS)

    Osteosarcoma (OS) is the most common nonhematolymphoid primary bone malignancy characterized by osteoid or new bone formation. Lungs and bones are the most common sites of metastases. We report a case where unusual sites of the soft tissue recurrence from OS were detected on restaging fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography scan done post 6 years of disease free interval

  12. Use of a high density lead glass tubing projection chamber in positron emission tomography and in high energy physics

    International Nuclear Information System (INIS)

    We describe the principle of operation of a high density Projection Chamber, in which the converter/radiator and drift field shaping structures are combined in the form of high density (5 to 6 g/cm3) lead glass tubing. The main applications of this type of detector to Medical Physics (Positron Emission Tomography) and High Energy Physics (Electromagnetic Calorimetry) are discussed

  13. Preliminary safety evaluation of a cyclotron facility for positron emission tomography imaging

    International Nuclear Information System (INIS)

    This work describes the design characteristics of a medical imaging centre which uses positron emission tomography, with a cyclotron for fluorine-18 and nitrogen-13 production, and which has provided experimental information on operational data recorded by area dosimetry since 1995. Doses to radiopharmacy and medical staff have been measured both in normal work and in some handling incidents. Data on radiation levels in the installation have also been obtained and related to design details and shielding. Area dosimetry was carried out using a five-stationary detector network, with a sampling rate of 2 min-1, and by thermoluminescent dosimetry (TLD). Staff were also monitored by TLD, using extra chips for finger dosimetry and to duplicate individual whole-body dosimetry in order to measure doses in certain single operations. For normal work, average whole-body doses to radiopharmacy staff were between 0.03 and 0.28 mSv/month, wrist doses were between 0.42 and 2.67 mSv/month, and finger doses were between 1.4 and 7.7 mSv/day for the left hand and 0.8 and 2.4 mSv/day for the right hand; such variation reflects the differing expertise of staff and the role played by optimisation. Finger doses between 16 and 131 mSv were measured in handling incidents, and finger doses of 20.2 and 20.7 mSv for the left hand and 22.0 and 22.3 mSv for the right hand were measured during handling of a syringe without shielding, containing 3 GBq. For medical staff, contributions to the whole-body dose of 2.0 and 1.9 μSv/procedure were measured for injection and placing the patient on the examination couch, respectively. Dose measurement on the middle finger of the right hand gives an average of 70 μSv during the injection. The provisions regarding the shielding design have proved to be adequate and effective during a 3-year operational period. Operational doses to medical staff are comparatively low, while radiopharmacy staff are the most exposed. The finger doses in these professionals

  14. Study of the silicon photomultipliers and their applications in positron emission tomography

    International Nuclear Information System (INIS)

    This thesis deals with silicon photomultipliers (SiPM) used in scintillation detectors and their applications in positron emission tomography (PET). The study of the SiPM is mainly focused on the application to the proposed EndoTOFPET-US detector, which is a multi-modality PET detector facilitating the development of new biomarkers for pancreas and prostate cancers. A Monte Carlo simulation tool is developed for the optimization of the detector's single channel design. In order to obtain a 200 ps system coincidence time resolution and maximize the detector sensitivity, the requirements for the crystal geometry, light yield and SiPM photon detection efficiency are specified based on the simulation study. In addition, the nonlinear response of the SiPM can be corrected by the simulation tool and the energy resolution of the detector is extracted. A series of measurements are established to characterize SiPMs in a fast and reliable way with high precision. The static characterization measures the value of different components in the derived electrical model of the SiPM, whereas the dynamic characterization extracts parameters that is crucial for the operation of the SiPM. Several SiPM samples are tested and their characteristics are compared. The developed setup and the precision of the measurement fulfill the requirements of the quality assurance test for the commissioning of the EndoTOFPET-US detector. The test foresees large quantities of SiPMs to be characterized. In addition, the developed measuring procedure has contributed to the study of X-ray induced surface damage of a SiPM from Hamamatsu. Characteristics of the device are measured before and after irradiating the SiPM with different X-ray doses, the results are compared and discussed. A comparative study of a digital and an analog SiPM in gamma spectroscopy with the inorganic scintillator is presented. The characteristics of a prototype digital SiPM that is developed for the EndoTOFPETUS detector is

  15. Spatiotemporal Stability of Cu-ATSM and FLT Positron Emission Tomography Distributions During Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: In dose painting, in which functional imaging is used to define biological targets for radiation therapy dose escalation, changes in spatial distributions of biological properties during treatment can compromise the quality of therapy. The goal of this study was to assess the spatiotemporal stability of 2 potential dose painting targets—hypoxia and proliferation—in canine tumors during radiation therapy. Methods and Materials: Twenty-two canine patients with sinonasal tumors (14 carcinoma and 8 sarcoma) were imaged before hypofractionated radiation therapy with copper(II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) positron emission tomography/computed tomography (PET/CT) for hypoxia and 3′-deoxy-3′-18F-fluorothymidine (FLT) PET/CT for proliferation. The FLT scans were repeated after 2 fractions and the Cu-ATSM scans after 3 fractions. Midtreatment PET/CT images were deformably registered to pretreatment PET/CT images. Voxel-based Spearman correlation coefficients quantified the spatial stability of Cu-ATSM and FLT uptake distributions between pretreatment and midtreatment scans. Paired t tests determined significant differences between the patients' respective Cu-ATSM and FLT correlations coefficients. Standardized uptake value measures were also compared between pretreatment and midtreatment scans by use of paired t tests. Results: Spatial distributions of Cu-ATSM and FLT uptake were stable through midtreatment for both sarcomas and carcinomas: the population mean ± standard deviation in Spearman correlation coefficient was 0.88 ± 0.07 for Cu-ATSM and 0.79 ± 0.13 for FLT. The patients' Cu-ATSM correlation coefficients were significantly higher than their respective FLT correlation coefficients (P=.001). Changes in Cu-ATSM SUV measures from pretreatment to midtreatment were histology dependent: carcinomas experienced significant decreases in Cu-ATSM uptake (P<.05), whereas sarcomas did not (P>.20). Both histologies

  16. Spatiotemporal Stability of Cu-ATSM and FLT Positron Emission Tomography Distributions During Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, Tyler J.; Yip, Stephen; Jallow, Ngoneh [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin (United States); Forrest, Lisa J. [Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin (United States); Jeraj, Robert, E-mail: rjeraj@wisc.edu [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin (United States); Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin (United States)

    2014-06-01

    Purpose: In dose painting, in which functional imaging is used to define biological targets for radiation therapy dose escalation, changes in spatial distributions of biological properties during treatment can compromise the quality of therapy. The goal of this study was to assess the spatiotemporal stability of 2 potential dose painting targets—hypoxia and proliferation—in canine tumors during radiation therapy. Methods and Materials: Twenty-two canine patients with sinonasal tumors (14 carcinoma and 8 sarcoma) were imaged before hypofractionated radiation therapy with copper(II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) positron emission tomography/computed tomography (PET/CT) for hypoxia and 3′-deoxy-3′-{sup 18}F-fluorothymidine (FLT) PET/CT for proliferation. The FLT scans were repeated after 2 fractions and the Cu-ATSM scans after 3 fractions. Midtreatment PET/CT images were deformably registered to pretreatment PET/CT images. Voxel-based Spearman correlation coefficients quantified the spatial stability of Cu-ATSM and FLT uptake distributions between pretreatment and midtreatment scans. Paired t tests determined significant differences between the patients' respective Cu-ATSM and FLT correlations coefficients. Standardized uptake value measures were also compared between pretreatment and midtreatment scans by use of paired t tests. Results: Spatial distributions of Cu-ATSM and FLT uptake were stable through midtreatment for both sarcomas and carcinomas: the population mean ± standard deviation in Spearman correlation coefficient was 0.88 ± 0.07 for Cu-ATSM and 0.79 ± 0.13 for FLT. The patients' Cu-ATSM correlation coefficients were significantly higher than their respective FLT correlation coefficients (P=.001). Changes in Cu-ATSM SUV measures from pretreatment to midtreatment were histology dependent: carcinomas experienced significant decreases in Cu-ATSM uptake (P<.05), whereas sarcomas did not (P>.20). Both histologies

  17. Simplifications in analyzing positron emission tomography data: effects on outcome measures

    International Nuclear Information System (INIS)

    Initial validation studies of new radiotracers generally involve kinetic models that require a measured arterial input function. This allows for the separation of tissue binding from delivery and blood flow effects. However, when using a tracer in a clinical setting, it is necessary to eliminate arterial blood sampling due to its invasiveness and the extra burden of counting and analyzing the blood samples for metabolites. In some cases, it may also be necessary to replace dynamic scanning with a shortened scanning period some time after tracer injection, as is done with FDG (F-18 fluorodeoxyglucose). These approximations represent loss of information. In this work, we considered several questions related to this: (1) Do differences in experimental conditions (drug treatments) or populations affect the input function, and what effect, if any, does this have on the final outcome measure? (2) How do errors in metabolite measurements enter into results? (3) What errors are incurred if the uptake ratio is used in place of the distribution volume ratio? (4) Is one- or two-point blood sampling any better for FDG data than the standardized uptake value? and (5) If blood sampling is necessary, what alternatives are there to arterial blood sampling? The first three questions were considered in terms of data from human dynamic positron emission tomography (PET) studies under conditions of baseline and drug pretreatment. Data from [11C]raclopride studies and those from the norepinephrine transporter tracer (S,S)-[11C]O-methyl reboxetine were used. Calculation of a metabolic rate for FDG using the operational equation requires a measured input function. We tested a procedure based on two blood samples to estimate the plasma integral and convolution that occur in the operational equation. There are some tracers for which blood sampling is necessary. Strategies for brain studies involve using the internal carotids in estimating the radioactivity after correcting for partial

  18. Depressed cerebral oxygen metabolism in patients with chronic renal failure. A positron emission tomography study

    International Nuclear Information System (INIS)

    In order to elucidate brain oxygen metabolism in uremic patients, the regional cerebral blood flow (rCBF), oxygen extraction (rOEF) and oxygen metabolism (rCMRO2) were measured by positron emission tomography (PET) in both 10 hemodialysis patients (HD: male [m]/female [f]=2/8, age of 49±3 [SEM] years old, HD duration of 113±26 months) and 13 pre-dialysis renal failure patients (CRF: m/f=10/3, age of 61±2 years old, serum creatinine (SCr) of 6.3±1.0 mg/dl). Data were compared with 20 non-uremic subjects (Control: m/f=7/13, age of 62±2 years old, SCr of 0.9±0.1 mg/dl). They had no neurological abnormalities, congestive heart failure, history of cerebrovascular accident, diabetes mellitus, or symptomatic brain lesion on magnetic resonance imaging. The age of HD was significantly younger than the other groups (p2 in both HD (1.82±0.10 ml/min/100 g) and CRF (1.95±0.09) showed significantly lower values as compared to Control (2.23±0.05) (p<0.01, respectively). Hemispheric rCBF in HD (35.6±2.1 ml/100 g/min) and in CRF (36.1±2.1) were not different from that in Control (31.8±1.4). Hemispheric rOEF in CRF (45.7±1.6%) was significantly higher than that in Control (40.5±1.2%) (p<0.02), but that in HD (43.7±1.9%) did not increase significantly. These tendencies were similar in all regions of interest, especially in the cerebral cortices, but not in the cerebellum. All PET parameters in the frontal cortices tended to show the lowest value in renal failure patients. For all HD patients, rCBF in both the frontal cortex and the white matter correlated inversely with HD duration (frontal cortex: r=-0.649, p<0.05; white matter: r=-0.706, p<0.02). Based on these data, it is concluded that brain oxygen metabolism is depressed in renal failure patients on or before hemodialysis treatment. The cause for the depressed brain oxygen metabolism is considered to be due either to the dysregulation of cerebral circulation or to lower brain cell activity. (author)

  19. Image reconstruction for a Positron Emission Tomograph optimized for breast cancer imaging

    International Nuclear Information System (INIS)

    The author performs image reconstruction for a novel Positron Emission Tomography camera that is optimized for breast cancer imaging. This work addresses for the first time, the problem of fully-3D, tomographic reconstruction using a septa-less, stationary, (i.e. no rotation or linear motion), and rectangular camera whose Field of View (FOV) encompasses the entire volume enclosed by detector modules capable of measuring Depth of Interaction (DOI) information. The camera is rectangular in shape in order to accommodate breasts of varying sizes while allowing for soft compression of the breast during the scan. This non-standard geometry of the camera exacerbates two problems: (a) radial elongation due to crystal penetration and (b) reconstructing images from irregularly sampled data. Packing considerations also give rise to regions in projection space that are not sampled which lead to missing information. The author presents new Fourier Methods based image reconstruction algorithms that incorporate DOI information and accommodate the irregular sampling of the camera in a consistent manner by defining lines of responses (LORs) between the measured interaction points instead of rebinning the events into predefined crystal face LORs which is the only other method to handle DOI information proposed thus far. The new procedures maximize the use of the increased sampling provided by the DOI while minimizing interpolation in the data. The new algorithms use fixed-width evenly spaced radial bins in order to take advantage of the speed of the Fast Fourier Transform (FFT), which necessitates the use of irregular angular sampling in order to minimize the number of unnormalizable Zero-Efficiency Bins (ZEBs). In order to address the persisting ZEBs and the issue of missing information originating from packing considerations, the algorithms (a) perform nearest neighbor smoothing in 2D in the radial bins (b) employ a semi-iterative procedure in order to estimate the unsampled data

  20. Are restrictions to behaviour of patients required following fluorine-18 fluorodeoxyglucose positron emission tomographic studies?

    International Nuclear Information System (INIS)

    The clinical use of positron emission tomography (PET) is expanding rapidly in most European countries. It is likely therefore that patients receiving the tracer fluorine-18 fluorodeoxyglucose (18FDG) will be discharged to come into contact with family members, members of the public and ward staff. There are few direct measurements on which to base any recommendations with regard to radiation protection, and so we have measured the dose rates from patients undergoing clinical PET examinations in our centre. Seventy-five patients who underwent whole-body and brain 18FDG PET examinations were studied. Dose rates were measured at 0.1, 0.5, 1.0 and 2.0 m from the mid thorax on leaving the department. The median administered activity was 323 MBq with a 95th percentile value of 360 MBq. The median dose rates measured at the four distances were 90.0, 35.0, 14.0 and 5.0 μSv h-1 (the median dose rates per unit administered activity at 2 h post injection were 0.31, 0.11, 0.04 and 0.02 μSv h-1 MBq-1). The corresponding 95th percentile values were 174.0, 69.0, 29.0 and 7.5 μSv h-1 (0.43, 0.2, 0.08 and 0.03 μSv h-1 MBq-1). A number of social situations were modelled and an annual dose limit of 1 mSv was used to determine whether restrictive behavioural advice was required. In the case of nursing staff on wards a value of 6 mSv was regarded as the annual limit, which translates to a daily limit of approximately 24 μSv. There is no need for restrictive advice for patients travelling by public or private transport when they leave the department 2 h after the administration of 18FDG. Similarly, there is no need for restrictive advice with regard to their contact with partners, work colleagues or children of any age, although it should be stressed that children should not accompany the patient to the scanning department. The only possible area of concern is in an oncology ward, where patients may be regularly referred for PET investigations and other high activity radionuclide