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  1. Cerebral misery perfusion diagnosed using hypercapnic blood-oxygenation-level-dependent contrast functional magnetic resonance imaging: a case report

    Directory of Open Access Journals (Sweden)

    D'Souza Olympio

    2010-02-01

    Full Text Available Abstract Introduction Cerebral misery perfusion represents a failure of cerebral autoregulation. It is an important differential diagnosis in post-stroke patients presenting with collapses in the presence of haemodynamically significant cerebrovascular stenosis. This is particularly the case when cortical or internal watershed infarcts are present. When this condition occurs, further investigation should be done immediately. Case presentation A 50-year-old Caucasian man presented with a stroke secondary to complete occlusion of his left internal carotid artery. He went on to suffer recurrent seizures. Neuroimaging demonstrated numerous new watershed-territory cerebral infarcts. No source of arterial thromboembolism was demonstrable. Hypercapnic blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging was used to measure his cerebrovascular reserve capacity. The findings were suggestive of cerebral misery perfusion. Conclusions Blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging allows the inference of cerebral misery perfusion. This procedure is cheaper and more readily available than positron emission tomography imaging, which is the current gold standard diagnostic test. The most evaluated treatment for cerebral misery perfusion is extracranial-intracranial bypass. Although previous trials of this have been unfavourable, the results of new studies involving extracranial-intracranial bypass in high-risk patients identified during cerebral perfusion imaging are awaited. Cerebral misery perfusion is an important and under-recognized condition in which emerging imaging and treatment modalities present the possibility of practical and evidence-based management in the near future. Physicians should thus be aware of this disorder and of recent developments in diagnostic tests that allow its detection.

  2. Functional neuroanatomy in depressed patients with sexual dysfunction: blood oxygenation level dependent functional MR imaging

    International Nuclear Information System (INIS)

    To demonstrate the functional neuroanatomy associated with sexual arousal visually evoked in depressed males who have underlying sexual dysfunction using Blood Oxygenation Level Dependent-based fMRI. Ten healthy volunteers (age range 21-55: mean 32.5 years), and 10 depressed subjects (age range 23-51: mean 34.4 years, mean Beck Depression Inventory score of 39.6 ± 5.9, mean Hamilton Rating Scale Depression (HAMD)-17 score of 33.5 ± 6.0) with sexual arousal dysfunction viewed erotic and neutral video films during functional magnetic resonance imaging (fMRI) with 1.5 T MR scanner (GE Signa Horizon). The fMRI data were obtained from 7 oblique planes using gradient-echo EPI (flip angle/TR/TE=90 .deg. /6000 ms/50 ms). The visual stimulation paradigm began with 60 sec of black screen, 150 sec of neutral stimulation with a documentary video film, 30 sec of black screen, 150 sec of sexual stimulation with an erotic video film followed by 30 sec of black screen. The brain activation maps and their quantification were analyzed by SPM99 program. There was a significant difference of brain activation between two groups during visual sexual stimulation. In depressed subjects, the level of activation during the visually evoked sexual arousal was significantly less than that of healthy volunteers, especially in the cerebrocortical areas of the hypothalamus, thalamus, caudate nucleus, and inferior and superior temporal gyri. On the other hand, the cerebral activation patterns during the neutral condition in both groups showed no significant differences (ρ < 0.01). This study is the first demonstration of the functional neuroanatomy of the brain associated with sexual dysfunction in depressed patients using fMRI. In order to validate our physiological neuroscience results, further studies that would include patients with other disorders and sexual dysfunction, and depressed patients without sexual dysfunction and their treatment response are needed

  3. Functional neuroanatomy in depressed patients with sexual dysfunction: blood oxygenation level dependent functional MR imaging

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    Yang, Jong Chul [Chonnam National Univ. Hospital, Kwangju (Korea, Republic of)

    2004-06-15

    To demonstrate the functional neuroanatomy associated with sexual arousal visually evoked in depressed males who have underlying sexual dysfunction using Blood Oxygenation Level Dependent-based fMRI. Ten healthy volunteers (age range 21-55: mean 32.5 years), and 10 depressed subjects (age range 23-51: mean 34.4 years, mean Beck Depression Inventory score of 39.6 {+-} 5.9, mean Hamilton Rating Scale Depression (HAMD)-17 score of 33.5 {+-} 6.0) with sexual arousal dysfunction viewed erotic and neutral video films during functional magnetic resonance imaging (fMRI) with 1.5 T MR scanner (GE Signa Horizon). The fMRI data were obtained from 7 oblique planes using gradient-echo EPI (flip angle/TR/TE=90 .deg. /6000 ms/50 ms). The visual stimulation paradigm began with 60 sec of black screen, 150 sec of neutral stimulation with a documentary video film, 30 sec of black screen, 150 sec of sexual stimulation with an erotic video film followed by 30 sec of black screen. The brain activation maps and their quantification were analyzed by SPM99 program. There was a significant difference of brain activation between two groups during visual sexual stimulation. In depressed subjects, the level of activation during the visually evoked sexual arousal was significantly less than that of healthy volunteers, especially in the cerebrocortical areas of the hypothalamus, thalamus, caudate nucleus, and inferior and superior temporal gyri. On the other hand, the cerebral activation patterns during the neutral condition in both groups showed no significant differences ({rho} < 0.01). This study is the first demonstration of the functional neuroanatomy of the brain associated with sexual dysfunction in depressed patients using fMRI. In order to validate our physiological neuroscience results, further studies that would include patients with other disorders and sexual dysfunction, and depressed patients without sexual dysfunction and their treatment response are needed.

  4. Experimental study of renal damage assessment after injection of iodine contrast medium: the role of blood oxygen level-dependent functional MRI with a 3.0 T system

    International Nuclear Information System (INIS)

    Objective: To evaluate blood oxygen level-dependent (BOLD) MRI on assessing renal damage after injection of iodine contrast medium with a 3.0 T system. Methods: Routine MRI examination, including T1WI and T2WI, and BOLD MRI were performed in 29 SD rats with a 3.0 T system before the injection of iodine contrast agent and 20 min, 24 h, 48 h, 72 h after the injection, respectively. T2 * and R2 * (=1/T2 *) measurements were obtained in the cortex, inner and outer medulla of kidney, respectively. The results obtained before contrast agent administration were considered as the self-controls. AVONA test were used for the comparison of R2 * values in different parts of both kidneys before contrast agent administration. Two-sample t test was used to compare R2 * values before and at each time point after contrast agent administration, and R2 * values in different parts of the kidneys. Results: Before contrast agent administration, R2 * values in outer medulla in both sides of kidney [R2 * leftOM =(31.76±2.73)/s , R2 * rightOM = (32.77±3.07)/s] were higher than those in cortex [R2 * leftC = (30.20±3.48)/s, R2 * rightC =(28.84±3.11)/s] and in inner medulla [R2 * leftIM =(29.54±2.42)/s, R2 * rightIM = (28.37±2.80)/s] (F=3.357 and 14.961, P2 * values in the three parts between left and right kidney, including cortex, outer and inner medulla (P>0.05). After contrast agent administration, R2 * values in outer medulla changed obviously, which reached to the peak values at 20 minutes after contrast agent administration [R2 * leftOM =(43.57±3.84)/s, R2 * rightOM =(44.58±3.13)/s] and dropped from 24 hours [R2 * leftOM =(42.07±4.82)/s, R2 * rightOM =(42.89±3.40)/s]. R2 * values in inner medulla and cortex only presented slight changes. Conclusion: R2 * values reflected the changes of oxygen content in renal cortex and medulla quantitatively, which helped for detecting medullar ischemia and hypoxia. BOLD MR imaging could offer a feasible method for evaluating oxygen

  5. Multi-regional investigation of the relationship between functional MRI blood oxygenation level dependent (BOLD activation and GABA concentration.

    Directory of Open Access Journals (Sweden)

    Ashley D Harris

    Full Text Available Several recent studies have reported an inter-individual correlation between regional GABA concentration, as measured by MRS, and the amplitude of the functional blood oxygenation level dependent (BOLD response in the same region. In this study, we set out to investigate whether this coupling generalizes across cortex. In 18 healthy participants, we performed edited MRS measurements of GABA and BOLD-fMRI experiments using regionally related activation paradigms. Regions and tasks were the: occipital cortex with a visual grating stimulus; auditory cortex with a white noise stimulus; sensorimotor cortex with a finger-tapping task; frontal eye field with a saccade task; and dorsolateral prefrontal cortex with a working memory task. In contrast to the prior literature, no correlation between GABA concentration and BOLD activation was detected in any region. The origin of this discrepancy is not clear. Subtle differences in study design or insufficient power may cause differing results; these and other potential reasons for the discrepant results are discussed. This negative result, although it should be interpreted with caution, has a larger sample size than prior positive results, and suggests that the relationship between GABA and the BOLD response may be more complex than previously thought.

  6. Application of language blood oxygenation level dependent functional MRI in the navigating operation of neurosurgery

    International Nuclear Information System (INIS)

    Objective: To verify the accuracy of blood oxygenation level dependent (BOLD)-based activation using electrocortical stimulation mapping (ESM) and explore the value of language fMRI in the navigating operation of neurosurgery. Methods: In 8 cases with brain tumors, BOLD-fMRI examinations were done before the operations. Under the state of awake anesthesia,the patients were aroused and ESM was conducted. Point-to-point comparison between the BOLD signal activations and the ESM was carried out under the surveillance of the neuro-navigation technology. In order to observe the sensibility and specificity of BOLD activations, the location of BOLD activations and the point of ESM was compared to calculate the stimulating positive points inside the regions of BOLD signals (real positive), outside BOLD regions (pseudo- negative), the stimulating negative points inside the regions of BOLD signals (pseudo-positive), and outside BOLD region (real negative). Two kinds of criteria for assessment were used. One was that the positive stimulating points were located in BOLD regions, and the other was that the positive stimulating points were located within 1 cm around the range of BOLD regions. Removal of the lesions were conducted with the tissue 1 cm around the language region preserved, and the cortex inside 0.5-1.0 cm distance from the positive points were retained. Results: Of the 8 cases, only 6 finished the tasks. Among them, 3 cases were with astrocytoma of grade 2, 2 were with astrocytoma of grade 3, and one with glioblastoma. The total number of stimulating points was 48, among which the positive points were 11. When the first criteria was applied, the sensitivity was 72.7% (8/11), and the specificity was 81.8% (30/37). When the second criteria was applied, the sensitivity was 82.0% (9/11), and the specificity was 75.6% (28/37). Follow-up after operation showed no aphasia occurred. Conclusions: BOLD-fMRI had a high sensitivity and specificity in displaying the language

  7. Preoperative 3T high field blood oxygen level dependent functional magnetic resonance imaging for glioma involving sensory cortical areas

    Institute of Scientific and Technical Information of China (English)

    LI Shao-wu; WANG Jiang-fei; JIANG Tao; LI Shou-wei; ZHANG Wen-bo; LI Zi-xiao; ZHANG Zhong; DAI Jian-ping; WANG Zhong-cheng

    2010-01-01

    Background Localization of sensory cortical areas during the operation is essential to preserve the sensory function.Intraoperative direct electrostimulation under awake anesthesia is the golden standard but time-consuming. We applied 3T high field blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to identify the relationship between glioma and cortical sensory areas preoperatively and to guide intraoperative direct electrostimulation for quick and precise localization.Methods Five glioma patients with sensory cortex involvement by or next to the lesion had preoperative BOLD fMRI to determine the spatial relationship of cortical sensory areas to the tumours. Bilateral hand opposite movement was performed by these patients for fMRI. Precentral and postcentral gyri were identified by electrical stimulation during the operation. Karnofsky Performance Status scores of the patients' pre- and postoperative and the role of BOLD fMRI were evaluated.Results The cortical sensory areas were all activated in five glioma patients involving postcentral gyrus areas by BOLDf MRI with bilateral hand opposite movement. The detected activation areas corresponded with the results from cortical electrical stimulation.Conclusions The relationship between cortical sensory areas and tumour can be accurately shown by BOLD fMRI before operation. And the information used to make the tumour resection could obtain good clinical results.

  8. Preoperative blood oxygen level-dependent functional magnetic resonance imaging in patients with gliomas involving the motor cortical areas

    Institute of Scientific and Technical Information of China (English)

    XIE Jian; CHEN Xu-zhu; JIANG Tao; LI Shou-wei; LI Zi-xiao; ZHANG Zhong; DAI Jian-ping; WANG Zhong-cheng

    2008-01-01

    Background Blood oxygen level-dependent(BOLD)functional magnetic resonance imaging(fMRI)plays an important role in identifying functional cortical areas of the brain.especially In patients with gliomas.This study aimed to assess the value of fMRI in presurgical planning and functional outcome of patients with gliomas in the motor cortical areas.Methods Twenty-six patients with gliomas in the motor cortex were recruited in the study.Before operation.fMRI was performed in each patient to obtain the mapping of bilateral hands area on the primary sensorimotor cortex.This examination was performed on a 3.0T scanner with a bilateral hands movement paradigm.During microsurgery under awake anesthesia,the motor area was identified using direct electrical stimulation and compared with preoperative mapping.Finally the tumor was resected as much as possible with the motor cortex preserved in each patlent.Karnofsky performance status(KPS)was evaluated in all patients before and after operation.Results Twenty-three patients showed a successful fMRI mapping.Among them,19 were calssified to be grade Ⅲ;4,grade Ⅱ;3,grade Ⅰ.The operation time was about 7 hours in the 23 patients,8.5 hours in the other 3.The pre- and pOstODerative KPS score was 82.3±8.6 and 94.2±8.1,respectively.Conclusions Preoperative fMRI of the hand motor area shows a high consistency with intraoperative cortical electronic stimulation.Combined use of the two methods shows a maximum benefit in surgical treatment.

  9. Blood oxygenation level dependent functional MRI study on the changes of motor cortex in patients with amyotrophic lateral sclerosis

    International Nuclear Information System (INIS)

    Objective: To study the changes of motor cortex in patients with amyotrophic lateral sclerosis (ALS) while executing sequential finger tapping movement by using blood oxygenation level dependent (BOLD) functional MRI. Methods: Fifteen patients with definite or probable ALS and 15 age and gender matched normal controls were enrolled in the BOLD study, and all the subjects were right-handed with no other diseases or any recent medication history. A 3.0 T MR scanner' was employed and gradient echo EPI (GRE-EPI)sequence was used to acquire the functional images. Subjects executed sequential finger tapping movement at a frequency of 1-2 Hz during a block design task. fMRI data were analyzed by using statistical parametric mapping (SPM) 2. Volume of activated brain areas was compared with the use of a Student's t-test. Results: Bilateral primary sensorimotor cortex (PSM), bilateral posterior aspect of premotor area (PA), bilateral supplementary motor area (SMA), contralateral inferior lateral premotor area (ILPA), bilateral parietal region (PAR), and ipsilateral cerebellum showed activation in both ALS patients and normal controls when executing the same motor task. The activation areas in bilateral PSM and bilateral posterior aspect of PA ( right hand ipsilateral activation: ALS (924.5±141.1) mm3, control (829.9± 98.4) mm3, P=0.05; right hand contralateral activation: ALS (9143.8±702.8) mm3, control (8638.8±506.4) mm3 P3, control (902.5±3 184.2)mm, P3, control (5934.6±616.4) mm3, P3, control (4710.7±416.3) mm3, P3, control (3688.9±672.3) mm3, P3, control (254.3±84.4) mm3, P3, control (1689.0±719.6) mm3, P<0.05) were significantly larger in ALS patients than in normal controls. Extra activation areas including ipsilateral ILPA, contralateral cerebellum and bilateral posterior limb of internal capsule were only detected in ALS patients. Conclusions: Similar activation areas were seen in both groups while executing the same motor task, but the activated areas

  10. Angioplasty and stenting for severe vertebral artery oriifce stenosis:effects on cerebellar function remodeling veriifed by blood oxygen level-dependent functional magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    Bo Liu; Zhiwei Li; Peng Xie

    2014-01-01

    Vertebral artery oriifce stenting may improve blood supply of the posterior circulation of the brain to regions such as the cerebellum and brainstem. However, previous studies have mainly focused on recovery of cerebral blood lfow and perfusion in the posterior circulation after inter-ventional therapy. This study examined the effects of functional recovery of local brain tissue on cerebellar function remodeling using blood oxygen level-dependent functional magnetic reso-nance imaging before and after interventional therapy. A total of 40 Chinese patients with severe unilateral vertebral artery oriifce stenosis were enrolled in this study. Patients were equally and randomly assigned to intervention and control groups. The control group received drug treat-ment only. The intervention group received vertebral artery oriifce angioplasty and stenting+identical drug treatment to the control group. At 13 days after treatment, the Dizziness Handicap Inventory score was compared between the intervention and control groups. Cerebellar function remodeling was observed between the two groups using blood oxygen level-dependent function-al magnetic resonance imaging. The improvement in dizziness handicap and cerebellar function was more obvious in the intervention group than in the control group. Interventional therapy for severe vertebral artery oriifce stenosis may effectively promote cerebellar function remodeling and exert neuroprotective effects.

  11. Noninvasive Monitoring of Microvascular Changes With Partial Irradiation Using Dynamic Contrast-Enhanced and Blood Oxygen Level-Dependent Magnetic Resonance Imaging

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    Lin, Yu-Chun [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Electrical Engineering, Chang Gung University, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Wang, Jiun-Jie [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Hong, Ji-Hong [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Lin, Yi-Ping [Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Lee, Chung-Chi [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Wai, Yau-Yau; Ng, Shu-Hang; Wu, Yi-Ming [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Wang, Chun-Chieh, E-mail: jjwang@adm.cgmh.org.tw [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China)

    2013-04-01

    Purpose: The microvasculature of a tumor plays an important role in its response to radiation therapy. Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) and blood oxygen level-dependent (BOLD) MRI are both sensitive to vascular characteristics. The present study proposed a partial irradiation approach to a xenograft tumor to investigate the intratumoral response to radiation therapy using DCE and BOLD MRI. Methods and Materials: TRAMP-C1 tumors were grown in C57BL/6J mice. Partial irradiation was performed on the distal half of the tumor with a single dose of 15 Gy. DCE MRI was performed to derive the endothelium transfer constant, K{sup trans}, using pharmacokinetic analysis. BOLD MRI was performed using quantitative R2* measurements with carbogen breathing. The histology of the tumor was analyzed using hematoxylin and eosin staining and CD31 staining to detect endothelial cells. The differences between the irradiated and nonirradiated regions of the tumor were assessed using K{sup trans} values, ΔR2* values in response to carbogen and microvascular density (MVD) measurements. Results: A significantly increased K{sup trans} and reduced BOLD response to carbogen were found in the irradiated region of the tumor compared with the nonirradiated region (P<.05). Histologic analysis showed a significant aggregation of giant cells and a reduced MVD in the irradiated region of the tumor. The radiation-induced difference in the BOLD response was associated with differences in MVD and K{sup trans}. Conclusions: We demonstrated that DCE MRI and carbogen-challenge BOLD MRI can detect differential responses within a tumor that may potentially serve as noninvasive imaging biomarkers to detect microvascular changes in response to radiation therapy.

  12. Blood oxygenation-level dependent functional MRI in evaluating the selective activation of motor cortexes associated with recovery of motor function in hemiplegic patients with ischemic stroke

    Institute of Scientific and Technical Information of China (English)

    Yuechun Li; Xiaoyan Liu; Guorong Liu; Ying He; Baojun Wang; Furu Liang; Li Wang; Hui Zhang; Jingfen Zhang; Ruiming Li

    2006-01-01

    BACKGROUND: Previous studies about blood oxygenation-level dependent (BOLD) functional MRI (fMRI) have indicated that the poststroke recovery of motor function is accompanied by the selective activation of motor cor texes with high correlation.OBJECTIVE: To evaluate the short-term outcomes after rehabilitative interventions with BOLD fMRI in hemi plegic patients with acute stroke, and analyze the correlation of the excitement of brain function in the passive and active movements of the affected limb with the recovery of motor function. DESIGN : A case observation. SETTING: Department of Neurology, Baotou Central Hospital. PARTICIPANTS: Thirty hemiplegic inpatients with ischemic stroke were selected from the Department of Neurology, Baotou Central Hospital from January to December in 2005, including 16 males and 14 females, aging 44-71 years with an average age of (56±5) years, and the disease course ranged from 12 to 72 hours. Inclusive criteria: In accordance with the diagnostic standard of ischemic stroke revised by the Fourth National Academic Meeting for Cerebrovascular Disease; Confirmed by cranial CT or MRI. They were all informed agreed with the detected items.METHODS: ① The Bobath technique was adopted in the rehabilitative interventions of the 30 patients, 30 minutes for each time, twice a day for three weeks continuously. ② The hand motor recovery of the stroke patients was graded by the Brunnstrom,stages ( Ⅰ -Ⅵ), and be able to grasp various objects and extend for the whole range was taken as grade Ⅵ. ③ The patients were examined with fMRI BOLD before rehabilitation and 3 weeks after rehabilitation. All the patients were trained with finger movements, the distracting thoughts should be eliminated as much as possible especially during the movement phase, the patients should highly concentrate on the hand movements. The range for the finger movements should be as large as possible with moderate frequency. The hand movements should be 10 s with

  13. Mapping of cerebral metabolic rate of oxygen using dynamic susceptibility contrast and blood oxygen level dependent MR imaging in acute ischemic stroke

    International Nuclear Information System (INIS)

    MR-derived cerebral metabolic rate of oxygen utilization (CMRO2) has been suggested to be analogous to PET-derived CMRO2 and therefore may be used for detection of viable tissue at risk for infarction. The purpose of this study was to evaluate MR-derived CMRO2 mapping in acute ischemic stroke in relation to established diffusion- and perfusion-weighted imaging. In 23 patients (mean age 63 ± 18.7 years, 11 women) with imaging findings for acute ischemic stroke, relative oxygen extraction fraction was calculated from quantitative transverse relaxation times (T2, T2*) and relative cerebral blood volume using a quantitative blood oxygenation level dependent (BOLD) approach in order to detect a local increase of deoxyhemoglobin. Relative CMRO2 (rCMRO2) maps were calculated by multiplying relative oxygen extraction fraction (rOEF) by cerebral blood flow, derived from PWI. After co-registration, rCMRO2 maps were evaluated in comparison with apparent diffusion coefficient (ADC) and time-to-peak (TTP) maps. Mean rCMRO2 values in areas with diffusion-restriction or TTP/ADC mismatch were compared with rCMRO2 values in the contralateral tissue. In tissue with diffusion restriction, mean rCMRO2 values were significantly decreased compared to perfusion-impaired (17.9 [95 % confidence interval 10.3, 25.0] vs. 58.1 [95 % confidence interval 50.1, 70.3]; P < 0.001) and tissue in the contralateral hemisphere (68.2 [95 % confidence interval 61.4, 75.0]; P < 0.001). rCMRO2 in perfusion-impaired tissue showed no significant change compared to tissue in the contralateral hemisphere (58.1 [95 % confidence interval 50.1, 70.3] vs. 66.7 [95 % confidence interval 53.4, 73.4]; P = 0.34). MR-derived CMRO2 was decreased within diffusion-restricted tissue and stable within perfusion-impaired tissue, suggesting that this technique may be adequate to reveal different pathophysiological stages in acute stroke. (orig.)

  14. Mapping of cerebral metabolic rate of oxygen using dynamic susceptibility contrast and blood oxygen level dependent MR imaging in acute ischemic stroke

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    Gersing, Alexandra S.; Schwaiger, Benedikt J. [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); University of California, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Ankenbrank, Monika; Toth, Vivien; Bauer, Jan S.; Zimmer, Claus [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Janssen, Insa [Technical University Munich, Department of Neurosurgery, Munich (Germany); Kooijman, Hendrik [Philips Healthcare, Hamburg (Germany); Wunderlich, Silke [Technical University Munich, Department of Neurology, Munich (Germany); Preibisch, Christine [Technical University Munich, Klinikum rechts der Isar, Department of Neuroradiology, Munich (Germany); Technical University Munich, Department of Neurology, Munich (Germany)

    2015-12-15

    MR-derived cerebral metabolic rate of oxygen utilization (CMRO{sub 2}) has been suggested to be analogous to PET-derived CMRO{sub 2} and therefore may be used for detection of viable tissue at risk for infarction. The purpose of this study was to evaluate MR-derived CMRO{sub 2} mapping in acute ischemic stroke in relation to established diffusion- and perfusion-weighted imaging. In 23 patients (mean age 63 ± 18.7 years, 11 women) with imaging findings for acute ischemic stroke, relative oxygen extraction fraction was calculated from quantitative transverse relaxation times (T2, T2*) and relative cerebral blood volume using a quantitative blood oxygenation level dependent (BOLD) approach in order to detect a local increase of deoxyhemoglobin. Relative CMRO{sub 2} (rCMRO{sub 2}) maps were calculated by multiplying relative oxygen extraction fraction (rOEF) by cerebral blood flow, derived from PWI. After co-registration, rCMRO{sub 2} maps were evaluated in comparison with apparent diffusion coefficient (ADC) and time-to-peak (TTP) maps. Mean rCMRO{sub 2} values in areas with diffusion-restriction or TTP/ADC mismatch were compared with rCMRO{sub 2} values in the contralateral tissue. In tissue with diffusion restriction, mean rCMRO{sub 2} values were significantly decreased compared to perfusion-impaired (17.9 [95 % confidence interval 10.3, 25.0] vs. 58.1 [95 % confidence interval 50.1, 70.3]; P < 0.001) and tissue in the contralateral hemisphere (68.2 [95 % confidence interval 61.4, 75.0]; P < 0.001). rCMRO{sub 2} in perfusion-impaired tissue showed no significant change compared to tissue in the contralateral hemisphere (58.1 [95 % confidence interval 50.1, 70.3] vs. 66.7 [95 % confidence interval 53.4, 73.4]; P = 0.34). MR-derived CMRO{sub 2} was decreased within diffusion-restricted tissue and stable within perfusion-impaired tissue, suggesting that this technique may be adequate to reveal different pathophysiological stages in acute stroke. (orig.)

  15. Blood oxygenation level dependent (BOLD). Renal imaging. Concepts and applications

    International Nuclear Information System (INIS)

    Many renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local field inhomogeneities and is based on a T2*-weighted sequence. BOLD is a non-invasive method allowing an estimation of the renal, particularly the medullary oxygenation, and an indirect measurement of blood flow without administration of contrast agents. Thus, effects of different drugs on the kidney and various renal diseases can be controlled and observed. This work will provide an overview of the studies carried out so far and identify ways how BOLD can be used in clinical studies. (orig.)

  16. Longitudial observation of dynamic changes in cortical function and white matter fibrous structure of patients with visual pathway lesions by blood oxygenation level dependent-functional magnetic resonance imaging combined with diffusion tensor imaging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    BACKGROUND: Functional magnetic resonance imaging (fMRI) is initially used for visual cortex location.However, the application of fMRI in investigating the development of visual pathway lesions needs to be further observed.OBJECTIVE: This study is to longitudially observe the dynamic changes in cortical function and white matter fibrous structure of patients with visual pathway lesions by blood oxygenation level dependent-functional magnetic resonance imaging (BOLD-fMRI) combined with diffusion tensor imaging (DTI), and to analyze the characteristics of brain function and structural recombination at convalescent period of lesions.DESIGN: Randomized controlled observation.SETTING: Department of Radiology, the General Hospital of Nanjing Military Area Command of Chinese PLA.PARTICIPANTS: Eight patients with unilateral or bilateral visual disorder caused by visual pathway lesions,who admitted to Department of Radiology, the General Hospital of Nanjing Military Area Command of Chinese PLA from January to September 2006 were involved, and served as experimental subjects. The patients, 6 males and 2 females, were aged 16 - 67 years. They had visual disorder confirmed by clinical examination, i.e. visual pathway lesion, which was further diagnosed by MR or CT. Another 12 subjects generally matching to those patients of experimental group in gender, age and sight, who received health examination in synchronization were involved and served as controls. The subjects had no history of eye diseases. Their binocular visual acuity (or corrected visual acuity) was over 1.0. Both routine examination of ophthalmology and examination of fundus were normal. Informed consents of detected items were obtained from all the subjects.METHODS: Signa Excite HD 1.5T magnetic resonance imaging system with 16 passages (GE Company,USA) and coil with 8 passages were used; brain functional stimulus apparatus (SAV-8800. Meide Company) was used for showing experimental mission. At the early stage

  17. Blood oxygenation level dependent (BOLD). Renal imaging. Concepts and applications; Blood Oxygenation Level Dependent (BOLD). Bildgebung der Nieren. Konzepte und Anwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Nissen, Johanna C.; Haneder, Stefan; Schoenberg, Stefan O.; Michaely, Henrik J. [Heidelberg Univ. Medizinische Fakultaet Mannheim (Germany). Inst. fuer Klinische Radiologie und Nuklearmedizin; Mie, Moritz B.; Zoellner, Frank G. [Heidelberg Univ. Medizinische Fakultaet Mannheim (DE). Inst. fuer Computerunterstuetzte Klinische Medizin (CKM)

    2010-07-01

    Many renal diseases as well as several pharmacons cause a change in renal blood flow and/or renal oxygenation. The blood oxygenation level dependent (BOLD) imaging takes advantage of local field inhomogeneities and is based on a T2{sup *}-weighted sequence. BOLD is a non-invasive method allowing an estimation of the renal, particularly the medullary oxygenation, and an indirect measurement of blood flow without administration of contrast agents. Thus, effects of different drugs on the kidney and various renal diseases can be controlled and observed. This work will provide an overview of the studies carried out so far and identify ways how BOLD can be used in clinical studies. (orig.)

  18. Blood oxygenation level-dependent response to intragastric load of corn oil emulsion in conscious rats.

    Science.gov (United States)

    Tsurugizawa, Tomokazu; Uematsu, Akira; Uneyama, Hisayuki; Torii, Kunio

    2009-12-01

    The postingestive actions after intragastric or oronasal stimulation of fat have been well investigated. The blood oxygenation level-dependent (BOLD) signal changes, however, after intragastric load of corn oil emulsion have yet to be elucidated. Here, using functional magnetic resonance imaging, we investigated the BOLD signal response to gut corn oil emulsion in nonanesthetized rats. Intragastrically infused 7% corn oil emulsion induced a BOLD signal increase in several brain regions, including the bilateral amygdala, hippocampus and the ventral tegmental area. These results indicate that the limbic system responds to gut corn oil emulsion and that activation of this system could promote the reinforcing action for food with high fat content. PMID:19918206

  19. 共济失调患者手运动时脑激活区域的定量分析%Quantitative analysis of the hand motor cortex in ataxia patients using blood oxygen level dependent functional magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    元小冬; 王小洁; 王德; 赵丽君; 王守红

    2010-01-01

    Objective To study the characteristics of the hand motor cortex in ataxia patients during active and passive finger-to-thumb opposition movements using bold oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI). Methods Ten right-handed healthy volunteers and 16 ataxia patients with motor cortex lesions were selected, and whole-brain BOLD-fMRI examinations were made while the subjects were performing the active and passive movements. Activated volume and intensity were recorded from the corresponding motor cortex and analyzed quantitatively. Meanwhile, the patients' coordination was evaluated using the international cooperative ataxia rating scale (ICARS). Results During passive movement of the ataxia patient's affected hands, the ipsilateral supplementary motor area (SMA) activated volume was larger than that during normal ipsilateral hand movement, and the activation intensity was also higher than that in the healthy controls. The ipsilateral cerebellum activated volume and intensity were significantly lower than those in the control group, and the frequency of appearance of the cerebellum was also less. The patients' activated volume and intensity in the ipsilateral cerebellum showed no correlation with ICARS scores. Conclusions When the ataxia patients' affected side cerebellum was dysfunctional, the ipsilateral SMA could compensate for the weak cerebellum function. The ICARS does not reflect cerebellum function.%目的 利用血氧水平依赖性功能性磁共振成像(BOLD-fMRI)技术,探讨共济失调患者在主动与被动复杂对指运动模式下关键脑功能区激活体积和强度的变化.方法 选取共济失调患者16例作为病例组,另选10名健康志愿者作为正常组.入选者均进行主动与被动复杂对指运动,在这两种运动模式下进行BOLD-fMRl检查,记录相应脑运动功能区的激活体积和强度并进行定量分析.采用共济失调量表(ICARS)对共济失调患者的

  20. Blood oxygenation level-dependent MRI for assessment of renal oxygenation

    Directory of Open Access Journals (Sweden)

    Neugarten J

    2014-11-01

    Full Text Available Joel Neugarten, Ladan Golestaneh Renal Division, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA Abstract: Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI has recently emerged as an important noninvasive technique to assess intrarenal oxygenation under physiologic and pathophysiologic conditions. Although this tool represents a major addition to our armamentarium of methodologies to investigate the role of hypoxia in the pathogenesis of acute kidney injury and progressive chronic kidney disease, numerous technical limitations confound interpretation of data derived from this approach. BOLD MRI has been utilized to assess intrarenal oxygenation in numerous experimental models of kidney disease and in human subjects with diabetic and nondiabetic chronic kidney disease, acute kidney injury, renal allograft rejection, contrast-associated nephropathy, and obstructive uropathy. However, confidence in conclusions based on data derived from BOLD MRI measurements will require continuing advances and technical refinements in the use of this technique. Keywords: kidney, hypoxia, oxygenation, diabetes mellitus, chronic kidney disease, acute kidney injury, contrast-associated nephropathy, BOLD MRI

  1. Deciphering phonemes from syllables in blood oxygenation level-dependent signals in human superior temporal gyrus.

    Science.gov (United States)

    Zhang, Qingtian; Hu, Xiaolin; Luo, Huan; Li, Jianmin; Zhang, Xiaolu; Zhang, Bo

    2016-03-01

    Linguistic units such as phonemes and syllables are important for speech perception. How the brain encodes these units is not well understood. Many neuroimaging studies have found distinct representations of consonant-vowel syllables that shared one phoneme and differed in the other phoneme (e.g. /ba/ and /da/), but it is unclear whether this discrimination ability is due to the neural coding of phonemes or syllables. We combined functional magnetic resonance imaging with multivariate pattern analysis to explore this question. Subjects listened to nine Mandarin syllables in a consonant-vowel form. We successfully decoded phonemes from the syllables based on the blood oxygenation level-dependent signals in the superior temporal gyrus (STG). Specifically, a classifier trained on the cortical patterns elicited by a set of syllables, which contained two phonemes, could distinguish the cortical patterns elicited by other syllables that contained the two phonemes. The results indicated that phonemes have unique representations in the STG. In addition, there was a categorical effect, i.e. the cortical patterns of consonants were similar, and so were the cortical patterns of vowels. Further analysis showed that phonemes exhibited stronger encoding specificity in the mid-STG than in the anterior STG. PMID:26751256

  2. Megalophallus as a sequela of priapism in sickle cell anemia: use of blood oxygen level-dependent magnetic resonance imaging.

    Science.gov (United States)

    Kassim, A A; Umans, H; Nagel, R L; Fabry, M E

    2000-09-01

    Priapism is a common complication of sickle cell anemia. We report a little known sequela of priapism: painless megalophallus, with significant penile enlargement. The patient had had an intense episode of priapism 9 years previously and his penis remained enlarged. Blood oxygen level-dependent magnetic resonance imaging revealed enlarged, hypoxic corpora cavernosa. Megalophallus probably resulted from permanent loss of elasticity of the tunica albuginea due to severe engorgement during the episode of priapism. This sequela needs to be recognized by physicians because no intervention is necessary and sexual function seems to remain intact. PMID:10962334

  3. Application of Diffusion - weighted Imaging and Blood Oxygen Level - dependent MRI in the Evaluation of Renal Func-tion of Chronic Kidney Disease%磁共振扩散加权成像联合血氧水平依赖成像在慢性肾脏病肾功能评价中的应用

    Institute of Scientific and Technical Information of China (English)

    李成; 房向东; 罗丹丹; 龚良庚; 连珞; 曾磊; 周国盛; 樊烨; 徐高四; 涂卫平

    2014-01-01

    Objective To investigate the application of diffusion - weighted imaging(DWI)and blood oxygen level -dependent MRI(BOLD MRI)in the evaluation of renal function of chronic kidney disease(CKD), Methods A total of 50 pa-tients with CKD who went to Department of Nephrology,the Second Affiliated Hospital of Nanchang University from February to December in 2012,were included in CKD group,20 healthy volunteers were included in control group, The ADC and R2 * values of bilateral cortex and medulla were measured by DWI and BOLD MRI among two groups, According to GFR measured by 99 Tcm -DTPA scintigraphy,CKD group were divided into 3 groups:CKD1 stage group(16 cases);CKD2 stage group(13 cases);CKD3 stage group(21 cases), The changes of ADC and R2 * values among patients with different CKD stages were analyzed, A total of 18 patients received renal biopsy,the correlation between pathological lesion degree and ADC and R2 * values of cortex and medulla was analysed, Results The ADC and R2 * values of bilateral cortex and medulla in CKD1 group,CKD2 group and CKD3 group were significantly lower than those in control group(P 0, 05), The medullary R2 * values were correlated negatively with pathological lesion degree(r = - 0, 659,P 0,05);髓质 R2*值与病理损害积分呈负相关(r =-0,659,P <0,05)。结论肾实质 ADC 值可无创性反映 CKD 肾功能水平及肾脏病理状态的改变。R2*值可以评价 CKD 肾脏髓质的氧代谢的改变,且对于判断 CKD 肾脏病理损伤的程度有一定意义。

  4. Blood oxygenation level-dependent MRI for assessment of renal oxygenation

    OpenAIRE

    Neugarten J; Golestaneh L

    2014-01-01

    Joel Neugarten, Ladan Golestaneh Renal Division, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA Abstract: Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) has recently emerged as an important noninvasive technique to assess intrarenal oxygenation under physiologic and pathophysiologic conditions. Although this tool represents a major addition to our armamentarium of methodologies to investigate the role of hypoxia in the pathogenesis of acute...

  5. Increased regional homogeneity of blood oxygen level-dependent signals in occipital cortex of early blind individuals.

    Science.gov (United States)

    Liu, Chong; Liu, Yong; Li, Weilan; Wang, Dawei; Jiang, Tianzi; Zhang, Yunting; Yu, Chunshui

    2011-03-01

    Although resting-state functional magnetic resonance imaging has shown altered functional connectivity between visual and other brain areas in the early blind individuals, it cannot answer which brain area's local activities are changed. In this study, regional homogeneity, a measure of the homogeneity of the local blood oxygen level-dependent signals, was used for the first time to investigate the changes in the resting-state brain activity in the early blind individuals. Compared with age-matched and sex-matched sighted individuals, the early blind individuals showed increased regional homogeneity only in the occipital areas, which might be explained by the abnormal cortical development and/or experience-dependent plasticity, resulted from an early visual deprivation. PMID:21304328

  6. Vascular Steal Explains Early Paradoxical Blood Oxygen Level-Dependent Cerebrovascular Response in Brain Regions with Delayed Arterial Transit Times

    Directory of Open Access Journals (Sweden)

    Julien Poublanc

    2013-04-01

    Full Text Available Introduction: Blood oxygen level-dependent (BOLD magnetic resonance imaging (MRI during manipulation of inhaled carbon dioxide (CO2 can be used to measure cerebrovascular reactivity (CVR and map regions of exhausted cerebrovascular reserve. These regions exhibit a reduced or negative BOLD response to inhaled CO2. In this study, we sought to clarify the mechanism behind the negative BOLD response by investigating its time delay (TD. Dynamic susceptibility contrast (DSC MRI with the injection of a contrast agent was used as the gold standard in order to provide measurement of the blood arrival time to which CVR TD could be compared. We hypothesize that if negative BOLD responses are the result of a steal phenomenon, they should be synchronized with positive BOLD responses from healthy brain tissue, even though the blood arrival time would be delayed. Methods: On a 3-tesla MRI system, BOLD CVR and DSC images were collected in a group of 19 patients with steno-occlusive cerebrovascular disease. For each patient, we generated a CVR magnitude map by regressing the BOLD signal with the end-tidal partial pressure of CO2 (PETCO2, and a CVR TD map by extracting the time of maximum cross-correlation between the BOLD signal and PETCO2. In addition, a blood arrival time map was generated by fitting the DSC signal with a gamma variate function. ROI masks corresponding to varying degrees of reactivity were constructed. Within these masks, the mean CVR magnitude, CVR TD and DSC blood arrival time were extracted and averaged over the 19 patients. CVR magnitude and CVR TD were then plotted against DSC blood arrival time. Results: The results show that CVR magnitude is highly correlated to DSC blood arrival time. As expected, the most compromised tissues with the longest blood arrival time have the lowest (most negative CVR magnitude. However, CVR TD shows a noncontinuous relationship with DSC blood arrival time. CVR TD is well correlated to DSC blood arrival time

  7. Renal Blood Oxygenation Level-dependent Imaging in Longitudinal Follow-up of Donated and Remaining Kidneys.

    Science.gov (United States)

    Seif, Maryam; Eisenberger, Ute; Binser, Tobias; Thoeny, Harriet C; Krauer, Fabienne; Rusch, Aurelia; Boesch, Chris; Vogt, Bruno; Vermathen, Peter

    2016-06-01

    Purpose To determine renal oxygenation changes associated with uninephrectomy and transplantation in both native donor kidneys and transplanted kidneys by using blood oxygenation level-dependent (BOLD) MR imaging. Materials and Methods The study protocol was approved by the local ethics committee. Thirteen healthy kidney donors and their corresponding recipients underwent kidney BOLD MR imaging with a 3-T imager. Written informed consent was obtained from each subject. BOLD MR imaging was performed in donors before uninephrectomy and in donors and recipients 8 days, 3 months, and 12 months after transplantation. R2* values, which are inversely related to tissue partial pressure of oxygen, were determined in the cortex and medulla. Longitudinal R2* changes were statistically analyzed by using repeated measures one-way analysis of variance with post hoc pair-wise comparisons. Results R2* values in the remaining kidneys significantly decreased early after uninephrectomy in both the medulla and cortex (P oxygen content. In donors, R2* remained significantly decreased in both the medulla and cortex at 3 (P < .01) and 12 (P < .01) months. In transplanted kidneys, R2* remained stable during the first year after transplantation, with no significant change. Among donors, cortical R2* was found to be negatively correlated with estimated glomerular filtration rate (R = -0.47, P < .001). Conclusion The results suggest that BOLD MR imaging may potentially be used to monitor renal functional changes in both remaining and corresponding transplanted kidneys. (©) RSNA, 2016. PMID:26744926

  8. How bold is blood oxygenation level dependent (BOLD) magnetic resonance imaging of the kidney? Opportunities, challenges and future directions

    OpenAIRE

    Niendorf, T; Pohlmann, A.; Arakelyan, K.; Flemming, B; Cantow, K.; Hentschel, J.; Grosenick, D; Ladwig, M.; Reimann, H; Klix, S.; Waiczies, S; Seeliger, E.

    2015-01-01

    Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. Yet, in vivo assessment of renal haemodynamics and tissue oxygenation remains a challenge. Many of the established approaches are invasive, hence not applicable in humans. Blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) offers an alternative. BOLD-MRI is non-invasive and indicative of renal tissue oxygenation. Nonetheles...

  9. Blood oxygenation level-dependent MRI of the skeletal muscle during ischemia in patients with peripheral arterial occlusive disease

    International Nuclear Information System (INIS)

    Purpose: to compare calf muscle Blood Oxygenation Level-Dependent (BOLD) response during ischemia in patients suffering from peripheral arterial occlusive disease (PAOD) and age-matched non-PAOD subjects. Materials and methods: PAOD patients with symptoms of intermittent calf claudication and an age-matched control group underwent T2*-weighted single-shot multi-echo planar imaging on a whole-body MR scanner at 1.5 T. The muscle BOLD signal in the calf was acquired during 60 sec of baseline and 240 sec of ischemia induced by cuff compression. T2* time courses in four calf muscles were evaluated. Results: significant differences in the mean T2* values were noted after 150 sec of measurement (p < 0.05). Patients with PAOD revealed a significantly reduced BOLD signal decrease compared to an age-matched control group. Conclusion: potential cause for this observation may be changes in the structure and/or the metabolic turnover of the muscle in PAOD patients. (orig.)

  10. Blood oxygenation level-dependent MRI of the skeletal muscle during ischemia in patients with peripheral arterial occlusive disease

    Energy Technology Data Exchange (ETDEWEB)

    Potthast, Silke [Unispital Basel, Inst. fuer Radiologie (Switzerland); Schulte, A. [Univ. Hospital Ulm (Germany). Clinic for Radiation Therapy and Radiooncology; Kos, S.; Bilecen, D. [Unispital Basel, Interventional Radiology (Switzerland); Aschwanden, M. [Unispital Basel (Switzerland). Angiologie

    2009-12-15

    Purpose: to compare calf muscle Blood Oxygenation Level-Dependent (BOLD) response during ischemia in patients suffering from peripheral arterial occlusive disease (PAOD) and age-matched non-PAOD subjects. Materials and methods: PAOD patients with symptoms of intermittent calf claudication and an age-matched control group underwent T2*-weighted single-shot multi-echo planar imaging on a whole-body MR scanner at 1.5 T. The muscle BOLD signal in the calf was acquired during 60 sec of baseline and 240 sec of ischemia induced by cuff compression. T2* time courses in four calf muscles were evaluated. Results: significant differences in the mean T2* values were noted after 150 sec of measurement (p < 0.05). Patients with PAOD revealed a significantly reduced BOLD signal decrease compared to an age-matched control group. Conclusion: potential cause for this observation may be changes in the structure and/or the metabolic turnover of the muscle in PAOD patients. (orig.)

  11. Blood oxygenation level-dependent magnetic resonance imaging during carbogen breathing: differentiation between prostate cancer and benign prostate hyperplasia and correlation with vessel maturity

    Science.gov (United States)

    Di, Ningning; Mao, Ning; Cheng, Wenna; Pang, Haopeng; Ren, Yan; Wang, Ning; Liu, Xinjiang; Wang, Bin

    2016-01-01

    Objective The aim of this study was to investigate whether the blood oxygenation level-dependent (BOLD) contrast magnetic resonance imaging (MRI) can evaluate tumor maturity and preoperatively differentiate prostate cancer (PCa) from benign prostate hyperplasia (BPH). Patients and methods BOLD MRI based on transverse relaxation time*-weighted echo planar imaging was performed to assess PCa (19) and BPH (22) responses to carbogen (95% O2 and 5% CO2). The average signal values of PCa and BPH before and after carbogen breathing and the relative increased signal values were computed, respectively. The endothelial-cell marker, CD31, and the pericyte marker, α-smooth muscle actin (mature vessels), were detected with immunofluorescence, and were assessed by microvessel density (MVD) and microvessel pericyte density (MPD). The microvessel pericyte coverage index (MPI) was used to evaluate the degree of vascular maturity. The changed signal from BOLD MRI was correlated with MVD, MPD, and MPI. Results After inhaling carbogen, both PCa and BPH showed an increased signal, but a lower slope was found in PCa than that in BPH (PMPI than BPH. The increased signal intensity was positively correlated with MPI in PCa and that in BPH (r=0.616, P=0.011; r=0.658, P=0.002); however, there was no correlation between the increased signal intensity and MPD or MVD in PCa than that in BPH (P>0.05). Conclusion Our results confirmed that the increased signal values induced by BOLD MRI well differentiated PCa from BPH and had a positive correlation with vessel maturity in both of them. BOLD MRI can be utilized as a surrogate marker for the noninvasive assessment of the degree of vessel maturity. PMID:27462169

  12. Characterization of the blood-oxygen level-dependent (BOLD) response in cat auditory cortex using high-field fMRI.

    Science.gov (United States)

    Brown, Trecia A; Joanisse, Marc F; Gati, Joseph S; Hughes, Sarah M; Nixon, Pam L; Menon, Ravi S; Lomber, Stephen G

    2013-01-01

    Much of what is known about the cortical organization for audition in humans draws from studies of auditory cortex in the cat. However, these data build largely on electrophysiological recordings that are both highly invasive and provide less evidence concerning macroscopic patterns of brain activation. Optical imaging, using intrinsic signals or dyes, allows visualization of surface-based activity but is also quite invasive. Functional magnetic resonance imaging (fMRI) overcomes these limitations by providing a large-scale perspective of distributed activity across the brain in a non-invasive manner. The present study used fMRI to characterize stimulus-evoked activity in auditory cortex of an anesthetized (ketamine/isoflurane) cat, focusing specifically on the blood-oxygen-level-dependent (BOLD) signal time course. Functional images were acquired for adult cats in a 7 T MRI scanner. To determine the BOLD signal time course, we presented 1s broadband noise bursts between widely spaced scan acquisitions at randomized delays (1-12 s in 1s increments) prior to each scan. Baseline trials in which no stimulus was presented were also acquired. Our results indicate that the BOLD response peaks at about 3.5s in primary auditory cortex (AI) and at about 4.5 s in non-primary areas (AII, PAF) of cat auditory cortex. The observed peak latency is within the range reported for humans and non-human primates (3-4 s). The time course of hemodynamic activity in cat auditory cortex also occurs on a comparatively shorter scale than in cat visual cortex. The results of this study will provide a foundation for future auditory fMRI studies in the cat to incorporate these hemodynamic response properties into appropriate analyses of cat auditory cortex. PMID:23000258

  13. Prognostic Significance of Transverse Relaxation Rate (R2*) in Blood Oxygenation Level-Dependent Magnetic Resonance Imaging in Patients with Invasive Breast Cancer

    Science.gov (United States)

    Choi, Hye Young; Ko, Eun Sook; Han, Boo-Kyung; Kim, Eun Ju; Kim, Sun Mi; Lim, Yaeji; Kim, Rock Bum

    2016-01-01

    Objective To examine the relationship between magnetic resonance transverse relaxation rate (R2*) and prognostic factors. Materials and Methods A total of 159 women with invasive ductal carcinomas (IDCs) underwent breast magnetic resonance imaging (MRI) including blood oxygenation level-dependent (BOLD) sequence at 3 T. The distribution of the measured R2* values were analyzed, and the correlation between R2* and various prognostic factors (age, tumor size, histologic grade, lymphovascular invasion, and axillary lymph node status, as well as expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, p53, and Ki-67) were retrospectively assessed using patient medical records. Results The baseline R2* values of the IDCs were very heterogeneous with wide range among the patients. The mean R2* value was (32.8 ± 14.0) Hz with a median of 29.3 Hz (range 13.5–109.4 Hz). In multivariate analysis, older age was associated with decreased R2* value (P = 0.011) and IDCs with p53-overexpression showed higher R2* values than those without p53-overexpression group (P = 0.031). Other prognostic factors were not significantly correlated with R2* value. Conclusion In this study, R2* values were significantly correlated with age and expression of p53. Further studies are necessary to determine the prognostic value of BOLD-MRI. PMID:27384310

  14. Blood oxygenation level-dependent MR imaging as a predictor of therapeutic response to concurrent chemoradiotherapy in cervical cancer: a preliminary experience

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Kyo; Park, Sung Yoon; Park, Byung Kwan [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea, Republic of); Park, Won; Huh, Seung Jae [Sungkyunkwan University School of Medicine, Department of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of)

    2014-07-15

    To investigate the value of blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) as a predictor of therapeutic response in cervical cancer patients undergoing concurrent chemoradiotherapy (CCRT). Thirty consecutive patients with biopsy-proven cervical cancer were examined by BOLD MRI before (preTx) and after CCRT (postTx). The R2* value (s{sup -1}) was calculated in the tumour and normal myometrium for preTx and postTx studies. Final tumour responses, as determined by changes of tumour size or volume on MRI, were correlated with tumour R2* values at preTx. The mean R2* values of tumours at preTx (21.1) were significantly lower than those at postTx (39.4 s{sup -1}) (p < 0.001), while those of normal myometrium were similar between preTx and postTx (p = 0.363). At preTx, tumour R2* values showed significantly negative correlation with final tumour size response (p = 0.022, Spearman's coefficient = -0.415). However, tumour R2* values at preTx were not associated with final tumour volume response (p = 0.069). BOLD MRI at 3 T, as an imaging biomarker, may have the potential to evaluate therapeutic response in cervical cancers. The association between BOLD MRI findings and CCRT responses warrants further validation. (orig.)

  15. Application of blood oxygen level-dependent magnetic resonance imaging in chronic kidney disease%血氧水平依赖磁共振成像在慢性肾病中的应用

    Institute of Scientific and Technical Information of China (English)

    王文娟; 郭燕; 李竹浩; 蔡华崧; 史瑶平; 杨栋

    2012-01-01

    背景:血氧水平依赖的磁共振成像是目前惟一能无创性地监测肾血氧含量的方法.目的:探讨血氧水平依赖的磁共振成像在评价慢性肾病患者肾血氧水平、反映肾功能状态方面的价值.方法:对20名健康志愿者和24名慢性肾病患者行肾脏血氧水平依赖的磁共振成像,测量各组肾皮质及髓质的R2*值,并进行统计学分析.结果与结论:正常肾髓质的R2*值高于皮质(P 0.05).慢性肾病患者皮质及髓质的R2*值均高于正常人(P 0.05). Patients with chronic kidney disease had higher cortical and medullary R2*than normal health (P < 0.05). There was a positive correlation between serum creatinine and renal R2* (r=0.564, P =0.004;r=0.588, P =0.003). This research shows that blood oxygen level-dependent magnetic resonance imaging can reflect renal bloodoxygen levels, and has certain value in evaluate the renal function.

  16. Correlation between single-trial visual evoked potentials and the blood oxygenation level dependent response in simultaneously recorded electroencephalography-functional magnetic resonance imaging

    DEFF Research Database (Denmark)

    Fuglø, Dan; Pedersen, Henrik; Rostrup, Egill;

    2012-01-01

    dependent variations in different occipital and extraoccipital cortical areas not explained by the boxcar regressor. The results suggest that the P1-N2 regressor is the best EEG-based regressor to model the visual paradigm, but when looking for additional effects like habituation or attention modulation...

  17. Dynamic contrast-enhanced magnetic resonance imaging: definitive imaging of placental function?

    Science.gov (United States)

    Chalouhi, G E; Deloison, B; Siauve, N; Aimot, S; Balvay, D; Cuenod, C A; Ville, Y; Clément, O; Salomon, L J

    2011-02-01

    The placenta constitutes a complex circulatory interface between the mother and fetus, but the relationship between the maternal and fetal circulation is still very difficult to study in vivo. There is growing evidence that magnetic resonance imaging (MRI) is useful and safe during pregnancy, and MRI is increasingly used for fetal and placental anatomical imaging. MRI functional imaging is now a modern obstetric tool and has the potential to provide new insights into the physiology of the human placenta. Placental perfusion has been studied during the first pass of an MR contrast agent, by arterial spin labeling, diffusion imaging, T1 and T2 relaxation time measurement using echo-planar imaging, and by a combination of magnetization transfer with established stereological methods. The BOLD (blood oxygen level-dependent) effect offers new perspectives for functional MRI evaluation of the placenta. PMID:20851065

  18. Mapping of cognitive functions in chronic intractable epilepsy: Role of fMRI

    OpenAIRE

    Kapil Chaudhary; S Senthil Kumaran; Chandra, Sarat P; Ashima Nehra Wadhawan; Manjari Tripathi

    2014-01-01

    Background: Functional magnetic resonance imaging (fMRI), a non-invasive technique with high spatial resolution and blood oxygen level dependent (BOLD) contrast, has been applied to localize and map cognitive functions in the clinical condition of chronic intractable epilepsy. Purpose: fMRI was used to map the language and memory network in patients of chronic intractable epilepsy pre- and post-surgery. Materials and Methods: After obtaining approval from the institutional ethics committee, s...

  19. Clinical application of blood oxygenation level-dependent MR imaging of kidney: A preliminary Study%肾脏血氧水平依赖MRI的初步应用

    Institute of Scientific and Technical Information of China (English)

    徐学勤; 陈楠; 李晓; 林晓珠; 朱晓雷; 倪根雄; 陈克敏; 严福华; 方文强; 徐耀文

    2012-01-01

    目的:探讨肾脏血氧水平依赖(blood oxygenation level-dependent,BOLD) MRI的临床应用价值.方法:对正常志愿者70例(无原发性和继发性肾病病史及肾功能损害危险因素)和57例慢性肾病患者进行GE 1.5THDMRI冠状面BOLD成像,分别测量其肾脏皮质及髓质的自旋弛豫率(R2*)值,并作对比分析.其中10例正常志愿者在1~6个月内进行了相同参数的冠状面BOLD成像检查.结果:T2*图像上,正常肾脏的结构清晰,皮质和髓质分界清,皮质和髓质R2*值分别为(12.63±1.40)/s和(18.14±2.51)/s,双侧肾脏皮质间(t=-1.333,P=0.186)、髓质间(t=0.958,P=0.341)的R2*值差异均无统计学意义.不同年龄及性别的志愿者间肾脏皮质、髓质R2*值亦均无统计学差异(P>0.05).10例志愿者重复BOLD成像肾脏R2*值无统计学差异.T2*图像上,慢性肾病患者的皮髓质分界不清.正常志愿者与慢性肾病患者间肾髓质R2*值差异有统计学意义(P<0.05).结论:肾脏BOLD MRI可清晰显示正常肾脏结构,有较好的可重复性,对慢性肾病患者肾髓质缺氧诊断较灵敏,具有较好的科研及临床应用前景.%Objective To evaluate the clinical application of blood oxygenation level-dependent (BOLD) MR imaging of kidney. Methods: Seventy healthy volunteers and 57 chronic kidney disease (CKD)patients underwent the BOLD MR imaging of the kidney with a 1.5-T MR imager (GE Signa Excite HD Twin-Speed 1.5T) . R2* of cortical and medullar portion of the kidney were calculated and compared. Reproducibility was assessed by repeating the same protocol in 10 randomly selected healthy volunteers after 1-6 months. R2* between patients and heallhy volunteers were compared. Results: In all healthy volunteers,there was a clear demarcation between cortex and medulla on T2* map. Medullary R2* were higher than cortical R2* (18.l4±2.51)/s,(12.63±1.40)/s. There was no difference in renal R2* between right and left kidney (Z.0.05),and no difference in

  20. A blood pool contrast aided T1 functional MRI in patients with brain tumors - a preliminary study

    International Nuclear Information System (INIS)

    The aim of our study was to determine the possibility of using a new functional technique: a T1-dependent sequence with administration of blood pool contrast agent (BPCA), in patients with brain tumors before and after surgical treatment. We also aimed to compare our results with those obtained using the fMRI technique, based on Blood Oxygenation Level-Dependent (BOLD) contrast. For each of our 14 oncologic patients (four before and ten after neurosurgical intervention), we obtained: a T1-3D GRE sequence (TR = 2.6 ms/TE = 1.1 ms/FA = 10 ) after intravenous administration of BPCA (0.03 mmol/kg), as well as a T2*EPI sequence (TR = 3 s/TE = 50 ms/FA = 90 ). Movement and/or tactile block type paradigms were carried out during both functional runs. SPM5 software was used for analysis. For both functional techniques, maximum activations were localized in the same areas. There were no significant differences observed in the t values calculated for activations located in the primary motor cortex between groups of pre- and post-intervention patients (in the same functional technique). The mean values for T2* EPI examinations were 10.84 and 9.36, respectively. The mean t values for the T1 technique were lower, especially for the post-intervention patients (5.83 and 3.9, respectively). The T1 technique can be used to detect functional areas in patients with brain tumors, pre-, and post-surgical intervention. This technique enables the evaluation of cortical centers that suffer from susceptibility artifacts when using the T2* BOLD technique. Activations found using both techniques have the same localization, with lower values for the T1 technique. (orig.)

  1. MR-based methods of the functional imaging of the CNS

    International Nuclear Information System (INIS)

    This review presents the basic principles of functional imaging of the central nervous system utilizing magnetic resonance imaging. The focus is set on visualization of different functional aspects of the brain and related pathologies. Additionally, clinical cases are presented to illustrate the applications of functional imaging techniques in the clinical setting. The relevant physics and physiology of contrast-enhanced and non-contrast-enhanced methods are discussed. The two main functional MR techniques requiring contrast-enhancement are dynamic T1- and T2*-MRI to image perfusion. Based on different pharmacokinetic models of contrast enhancement diagnostic applications for neurology and radio-oncology are discussed. The functional non-contrast enhanced imaging techniques are based on ''blood oxygenation level dependent (BOLD)-fMRI and arterial spin labeling (ASL) technique. They have gained clinical impact particularly in the fields of psychiatry and neurosurgery. (orig.)

  2. MR-based methods of the functional imaging of the CNS; MR-basierte Methoden der funktionellen Bildgebung des zentralen Nervensystems

    Energy Technology Data Exchange (ETDEWEB)

    Giesel, F.L.; Weber, M.A.; Zechmann, C.; Tengg-Kobligk, H. von; Essig, M.; Kauczor, H.U. [Radiologie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany); Wuestenberg, T. [Abt. fuer Medizinische Psychologie, Georg-August-Univ. Goettingen (Germany); Bongers, A.; Baudendistel, K.T. [Medizinische Physik in der Radiologie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany); Hahn, H.K. [MeVis, Zentrum fuer Medizinische Diagnosesysteme und Visualisierung, Bremen (Germany)

    2005-05-01

    This review presents the basic principles of functional imaging of the central nervous system utilizing magnetic resonance imaging. The focus is set on visualization of different functional aspects of the brain and related pathologies. Additionally, clinical cases are presented to illustrate the applications of functional imaging techniques in the clinical setting. The relevant physics and physiology of contrast-enhanced and non-contrast-enhanced methods are discussed. The two main functional MR techniques requiring contrast-enhancement are dynamic T1- and T2{sup *}-MRI to image perfusion. Based on different pharmacokinetic models of contrast enhancement diagnostic applications for neurology and radio-oncology are discussed. The functional non-contrast enhanced imaging techniques are based on ''blood oxygenation level dependent (BOLD)-fMRI and arterial spin labeling (ASL) technique. They have gained clinical impact particularly in the fields of psychiatry and neurosurgery. (orig.)

  3. 正常肾脏血氧依赖磁共振成像特点及与生理指标相关性研究%Blood Oxygen Level Dependent MRI of Normal Kidney and Its Correlation with Physiological Indexes

    Institute of Scientific and Technical Information of China (English)

    石会兰; 郑振峰; 马慧; 李峰坦; 张敬; 张云亭

    2014-01-01

    目的:探讨正常肾脏的血氧水平依赖磁共振(BOLD-MRI)成像特点,以及与部分生理指标之间的相关性。方法纳入90例行腹部磁共振检查的非肾脏病患者。使用GE 3.0 T磁共振扫描仪和Torsopa相控阵线圈,行肾脏冠状面T1WI及BOLD成像,BOLD-MRI成像扫描采用T2*自旋梯度回波(T2*SPGR)序列,BOLD影像分析采用R2*map后处理软件,分别从肾脏皮质和髓质区选取感兴趣区(ROI)测量表观自旋-自旋弛豫率(R2*)值。分析R2*值与患者年龄、性别、身高、体质量、体质量指数(BMI)、体表面积(BSA)和估算的肾小球滤过率(eGFR)之间的相关性。结果两侧肾脏皮质区R2*值[左侧(16.56±1.40)Hz和右侧(16.66±1.28)Hz]均低于相应髓质区[左侧(28.82±3.71)Hz和右侧(28.36±3.72)Hz];女性和男性患者皮质R2*值[女性(16.55±1.30)Hz和男性(16.66±1.38Hz)]也低于相应的髓质区[女性(28.46±3.64)Hz和男性(28.70±3.78)Hz]。双侧肾脏髓质区肾脏下极R2*值[(27.29±3.05)]Hz低于中极[(29.32±3.47)Hz]和上极[(29.16±4.21)Hz];差异均有统计学意义。髓质R2*值与年龄呈正相关,与eGFR呈负相关(r分别为0.284、-0.232,均P<0.05)。结论 R2*值可反映肾脏皮髓质氧分压的水平,判断其缺血缺氧程度。BOLD-MRI提供了一种简单、易行且无创性检测肾脏皮髓质氧代谢的方法。%Objective To explore the characteristics of blood oxygen level dependent (BOLD) magnetic resonance imaging (MRI) in healthy native kidneys. To investigate the relationship between BOLD-MRI and common physiological in-dexes. Methods GE 3.0T MRI scanner and Torsopa phased-array coil were employed to acquire renal coronal T1WI and BOLD image. Ninety patients who were ruled out chronic kidney diseases underwent BOLD-MRI with T2*-spoiled gradient recalled echo (T2*SPGR) sequence. BOLD images were analyzed on R2*map software. Cortical and

  4. Interhemispheric Functional Connectivity in Childhood Absence Epilepsy

    OpenAIRE

    J Gordon Millichap

    2011-01-01

    Using a blood oxygen level-dependent resting functional connectivity approach to analyze EEG-fMRI data, the properties of bihemispheric brain networks in 16 patients with childhood absence epilepsy (CAE) were investigated during the interictal period, in a study at Yale University School of Medicine, New Haven, CT.

  5. Tumor vascular architecture and function evaluated by non-invasive susceptibility MRI methods and immunohistochemistry.

    NARCIS (Netherlands)

    Robinson, S.P.; Rijken, P.F.J.W.; Howe, F.A.; McSheehy, P.M.; Sanden, B.P.J. van den; Heerschap, A.; Stubbs, M.; Kogel, A.J. van der; Griffiths, J.R.

    2003-01-01

    PURPOSE: To investigate the physiological origins responsible for the varying blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) responses to carbogen (95% O(2)/5% CO(2)) breathing observed with different tumor types. MATERIALS AND METHODS: Susceptibility contrast-enhanced MRI

  6. An Introduction to Normalization and Calibration Methods in Functional MRI

    Science.gov (United States)

    Liu, Thomas T.; Glover, Gary H.; Mueller, Bryon A.; Greve, Douglas N.; Brown, Gregory G.

    2013-01-01

    In functional magnetic resonance imaging (fMRI), the blood oxygenation level dependent (BOLD) signal is often interpreted as a measure of neural activity. However, because the BOLD signal reflects the complex interplay of neural, vascular, and metabolic processes, such an interpretation is not always valid. There is growing evidence that changes…

  7. Functional MRI of the visual cortex and visual testing in patients with previous optic neuritis

    DEFF Research Database (Denmark)

    Langkilde, Annika Reynberg; Frederiksen, J.L.; Rostrup, Egill; Larsson, H.B.W.

    2002-01-01

    activated area and the signal change following ON, and compared the results with results of neuroophthalmological testing. We studied nine patients with previous acute ON and 10 healthy persons served as controls using fMRI with visual stimulation. In addition to a reduced activated volume, patients showed...... a reduced blood oxygenation level dependent (BOLD) signal increase and a greater asymmetry in the visual cortex, compared with controls. The volume of visual cortical activation was significantly correlated to the result of the contrast sensitivity test. The BOLD signal increase correlated......The volume of cortical activation as detected by functional magnetic resonance imaging (fMRI) in the visual cortex has previously been shown to be reduced following optic neuritis (ON). In order to understand the cause of this change, we studied the cortical activation, both the size of the...

  8. Physiological basis and image processing in functional magnetic resonance imaging: Neuronal and motor activity in brain

    Directory of Open Access Journals (Sweden)

    Sharma Rakesh

    2004-05-01

    Full Text Available Abstract Functional magnetic resonance imaging (fMRI is recently developing as imaging modality used for mapping hemodynamics of neuronal and motor event related tissue blood oxygen level dependence (BOLD in terms of brain activation. Image processing is performed by segmentation and registration methods. Segmentation algorithms provide brain surface-based analysis, automated anatomical labeling of cortical fields in magnetic resonance data sets based on oxygen metabolic state. Registration algorithms provide geometric features using two or more imaging modalities to assure clinically useful neuronal and motor information of brain activation. This review article summarizes the physiological basis of fMRI signal, its origin, contrast enhancement, physical factors, anatomical labeling by segmentation, registration approaches with examples of visual and motor activity in brain. Latest developments are reviewed for clinical applications of fMRI along with other different neurophysiological and imaging modalities.

  9. An illustrated heuristic prototype facilitates scientific inventive problem solving: A functional magnetic resonance imaging study.

    Science.gov (United States)

    Tong, Dandan; Li, Wenfu; Tang, Chaoying; Yang, Wenjing; Tian, Yan; Zhang, Lei; Zhang, Meng; Qiu, Jiang; Liu, Yijun; Zhang, Qinglin

    2015-07-01

    Many scientific inventions (SI) throughout history were inspired by heuristic prototypes (HPs). For instance, an event or piece of knowledge similar to displaced water from a tub inspired Archimedes' principle. However, the neural mechanisms underlying this insightful problem solving are not very clear. Thus, the present study explored the neural correlates used to solve SI problems facilitated by HPs. Each HP had two versions: a literal description with an illustration (LDI) and a literal description with no illustration (LDNI). Thirty-two participants were divided randomly into these two groups. Blood oxygenation level-dependent fMRI contrasts between LDI and LDNI groups were measured. Greater activity in the right middle occipital gyrus (RMOG, BA19), right precentral gyrus (RPCG, BA4), and left middle frontal gyrus (LMFG, BA46) were found within the LDI group as compared to the LDNI group. We discuss these results in terms cognitive functions within these regions related to problem solving and memory retrieval. PMID:25840359

  10. Advances of blood oxygen-level dependent MRI in muscular system

    International Nuclear Information System (INIS)

    BOLD-fMRI has been applied to muscular system to observe muscular pathophysiological change after performing a task and show the characteristics of muscle perfusion. This paper mainly introduces the scanning sequence, common tasking methods, such as cuff compression, excise, oxygen and drug, etc. It also introduces clinical study of perfusion reserve of muscular tissue with abnormal blood vessels. (authors)

  11. The functional role of contrast adaptation

    OpenAIRE

    Mark W Greenlee; Heitger, F.

    1988-01-01

    Prolonged inspection of high contrast sinewave gratings increases the contrast required to detect gratings having a similar spatial frequency and orientation. The functional role of such adaptation has, however, in the past, eluded disclosure. We here show that 5 min adaptation to a 2 c/deg sinewave grating of 0.8 contrast changes the observer's ability to discriminate the contrast level of a subsequently presented grating of the same spatial frequency and orientation. Similar to the threshol...

  12. Luminance contrast of a visual stimulus modulates the BOLD response more than the cerebral blood flow response in the human brain

    OpenAIRE

    Liang, Christine L.; Ances, Beau M.; Perthen, Joanna E.; Moradi, Farshad; Liau, Joy; Buracas, Giedrius T.; Hopkins, Susan R.; Buxton, Richard B.

    2012-01-01

    The blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI) depends on the evoked changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in response to changes in neural activity. This response is strongly modulated by the CBF/CMRO2 coupling relationship with activation, defined as n, the ratio of the fractional changes. The reliability of the BOLD signal as a quantitative reflection of underlying physiological c...

  13. A review of functional magnetic resonance imaging for Brainnetome

    Institute of Scientific and Technical Information of China (English)

    Ming Song; Tianzi Jiang

    2012-01-01

    The functional brain network using blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has revealed the potentials for probing brain architecture,as well as for identifying clinical biomarkers for brain diseases.In the general context of Brainnetome,this review focuses on the development of approaches for modeling and analyzing functional brain networks with BOLD fMRI.The prospects for these approaches are also discussed.

  14. Functional MRI neurofeedback training on connectivity between two regions induces long-lasting changes in intrinsic functional network

    OpenAIRE

    Megumi, Fukuda; Yamashita, Ayumu; Kawato, Mitsuo; Imamizu, Hiroshi

    2015-01-01

    Motor or perceptual learning is known to influence functional connectivity between brain regions and induce short-term changes in the intrinsic functional networks revealed as correlations in slow blood-oxygen-level dependent (BOLD) signal fluctuations. However, no cause-and-effect relationship has been elucidated between a specific change in connectivity and a long-term change in global networks. Here, we examine the hypothesis that functional connectivity (i.e., temporal correlation between...

  15. Functional connectivity of the rat brain in magnetic resonance imaging

    OpenAIRE

    Kalthoff, Daniel

    2011-01-01

    INTRODUCTION: Functional connectivity – generally defined by Friston as “temporal correlation of a neurophysiological index measured in different brain areas” – was first reported for human functional magnetic resonance imaging (fMRI) of the brain by Biswal and co-workers in 1995. It relies on spontaneous low frequency fluctuations (< 0.1 Hz) of the blood oxygenation level dependent (BOLD) signal that are synchronized in distant brain regions in the absence of any task or stimulus, hence the ...

  16. BOLD signal and functional connectivity associated with loving kindness meditation

    OpenAIRE

    Garrison, Kathleen A.; Scheinost, Dustin; Constable, R. Todd; Brewer, Judson A.

    2014-01-01

    Loving kindness is a form of meditation involving directed well-wishing, typically supported by the silent repetition of phrases such as “may all beings be happy,” to foster a feeling of selfless love. Here we used functional magnetic resonance imaging to assess the neural substrate of loving kindness meditation in experienced meditators and novices. We first assessed group differences in blood oxygen level-dependent (BOLD) signal during loving kindness meditation. We next used a relatively n...

  17. Skeletal muscle microvascular function in girls with Turner syndrome

    OpenAIRE

    West, Sarah L.; Clodagh S. O'Gorman; Elzibak, Alyaa H.; Jessica Caterini; Noseworthy, Michael D.; Tammy Rayner; Jill Hamilton; Wells, Greg D

    2015-01-01

    Background: Exercise intolerance is prevalent in individuals with Turner Syndrome (TS). We recently demonstrated that girls with TS have normal aerobic but altered skeletal muscle anaerobic metabolism compared to healthy controls (HC). The purpose of this study was to compare peripheral skeletal muscle microvascular function in girls with TS to HC after exercise. We hypothesized that girls with TS would have similar muscle blood-oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) s...

  18. Anatomical and functional assemblies of brain BOLD oscillations

    OpenAIRE

    Baria, Alexis T.; Baliki, Marwan N; Parrish, Todd; Apkarian, A. Vania

    2011-01-01

    Brain oscillatory activity has long been thought to have spatial properties, the details of which are unresolved. Here we examine spatial organizational rules for the human brain oscillatory activity as measured by blood oxygen level-dependent (BOLD). Resting state BOLD signal was transformed into frequency space (Welch’s method), averaged across subjects, and its spatial distribution studied as a function of four frequency bands, spanning the full bandwidth of BOLD. The brain showed anatomic...

  19. Partially coherent contrast-transfer-function approximation.

    Science.gov (United States)

    Nesterets, Yakov I; Gureyev, Timur E

    2016-04-01

    The contrast-transfer-function (CTF) approximation, widely used in various phase-contrast imaging techniques, is revisited. CTF validity conditions are extended to a wide class of strongly absorbing and refracting objects, as well as to nonuniform partially coherent incident illumination. Partially coherent free-space propagators, describing amplitude and phase in-line contrast, are introduced and their properties are investigated. The present results are relevant to the design of imaging experiments with partially coherent sources, as well as to the analysis and interpretation of the corresponding images. PMID:27140752

  20. Developmental effects of aggressive behavior in male adolescents assessed with structural and functional brain imaging

    OpenAIRE

    Strenziok, Maren; Krueger, Frank; Heinecke, Armin; Lenroot, Rhoshel K.; Knutson, Kristine M.; Meer, Elke van der; Grafman, Jordan

    2009-01-01

    Aggressive behavior is common during adolescence. Although aggression-related functional changes in the ventromedial prefrontal cortex (vmPFC) and frontopolar cortex (FPC) have been reported in adults, the neural correlates of aggressive behavior in adolescents, particularly in the context of structural neurodevelopment, are obscure. We used functional and structural magnetic resonance imaging (MRI) to measure the blood oxygenation level-depended signal and cortical thickness. In a block-desi...

  1. Technical and conceptual considerations for performing and interpreting functional MRI studies in awake rats

    OpenAIRE

    MarceloFebo

    2011-01-01

    Functional neuroimaging studies in rodents have the potential to provide insight into neurodevelopmental and psychiatric conditions. The strength of the technique lies in its non-invasive nature that can permit longitudinal functional studies in the same animal over its adult life. The relatively good spatial and temporal resolution and the ever-growing database on the biological and biophysical basis of the blood oxygen level dependent (BOLD) signal make it a unique technique in preclinical ...

  2. Technical and Conceptual Considerations for Performing and Interpreting Functional MRI Studies in Awake Rats

    OpenAIRE

    Febo, Marcelo

    2011-01-01

    Functional neuroimaging studies in rodents have the potential to provide insight into neurodevelopmental and psychiatric conditions. The strength of the technique lies in its non-invasive nature that can permit longitudinal functional studies in the same animal over its adult life. The relatively good spatial and temporal resolution and the ever-growing database on the biological and biophysical basis of the blood oxygen level dependent (BOLD) signal make it a unique technique in preclinical ...

  3. Exploring brain function with magnetic resonance imaging

    International Nuclear Information System (INIS)

    Since its invention in the early 1990s, functional magnetic resonance imaging (fMRI) has rapidly assumed a leading role among the techniques used to localize brain activity. The spatial and temporal resolution provided by state-of-the-art MR technology and its non-invasive character, which allows multiple studies of the same subject, are some of the main advantages of fMRI over the other functional neuroimaging modalities that are based on changes in blood flow and cortical metabolism. This paper describes the basic principles and methodology of fMRI and some aspects of its application to functional activation studies. Attention is focused on the physiology of the blood oxygenation level-dependent (BOLD) contrast mechanism and on the acquisition of functional time-series with echo planar imaging (EPI). We also provide an introduction to the current strategies for the correction of signal artefacts and other image processing techniques. In order to convey an idea of the numerous applications of fMRI, we will review some of the recent results in the fields of cognitive and sensorimotor psychology and physiology

  4. Resting cerebral metabolism correlates with skin conductance and functional brain activation during fear conditioning

    OpenAIRE

    Linnman, Clas; Zeidan, Mohamed A.; Pitman, Roger K.; Milad, Mohammed R.

    2011-01-01

    We investigated whether resting brain metabolism can be used to predict autonomic and neuronal responses during fear conditioning in 20 healthy humans. Regional cerebral metabolic rate for glucose was measured via positron emission tomography at rest. During conditioning, autonomic responses were measured via skin conductance, and blood oxygen level dependent signal was measured via functional magnetic resonance imaging. Resting dorsal anterior cingulate metabolism positively predicted differ...

  5. The Neural Consequences of Repeated Cocaine Exposure Revealed by Functional MRI in Awake Rats

    OpenAIRE

    Febo, Marcelo; Segarra, Annabell C.; Nair, Govind; Schmidt, Karl; Duong, Timothy Q.; Ferris, Craig F.

    2005-01-01

    The use of functional magnetic resonance imaging (fMRI) in animal models of cocaine addiction is an invaluable tool for investigating the neuroadaptations that lead to this psychiatric disorder. We used blood-oxygen-level-dependent (BOLD) MRI in awake rats to identify the neuronal circuits affected by repeated cocaine administration. Rats were given an injection of cocaine (15 mg/kg, i.p.) or its vehicle for 7 days, abstained from injections for 1 week, and challenged with an intracerebrovent...

  6. Functional Magnetic Resonance Imaging in Acute Kidney Injury: Present Status

    Directory of Open Access Journals (Sweden)

    Hai Ying Zhou

    2016-01-01

    Full Text Available Acute kidney injury (AKI is a common complication of hospitalization that is characterized by a sudden loss of renal excretory function and associated with the subsequent development of chronic kidney disease, poor prognosis, and increased mortality. Although the pathophysiology of renal functional impairment in the setting of AKI remains poorly understood, previous studies have identified changes in renal hemodynamics, perfusion, and oxygenation as key factors in the development and progression of AKI. The early assessment of these changes remains a challenge. Many established approaches are not applicable to humans because of their invasiveness. Functional renal magnetic resonance (MR imaging offers an alternative assessment tool that could be used to evaluate renal morphology and function noninvasively and simultaneously. Thus, the purpose of this review is to illustrate the principle, application, and role of the techniques of functional renal MR imaging, including blood oxygen level-dependent imaging, arterial spin labeling, and diffusion-weighted MR imaging, in the management of AKI. The use of gadolinium in MR imaging may exacerbate renal impairment and cause nephrogenic systemic fibrosis. Therefore, dynamic contrast-enhanced MR imaging will not be discussed in this paper.

  7. Functional Magnetic Resonance Imaging in Acute Kidney Injury: Present Status.

    Science.gov (United States)

    Zhou, Hai Ying; Chen, Tian Wu; Zhang, Xiao Ming

    2016-01-01

    Acute kidney injury (AKI) is a common complication of hospitalization that is characterized by a sudden loss of renal excretory function and associated with the subsequent development of chronic kidney disease, poor prognosis, and increased mortality. Although the pathophysiology of renal functional impairment in the setting of AKI remains poorly understood, previous studies have identified changes in renal hemodynamics, perfusion, and oxygenation as key factors in the development and progression of AKI. The early assessment of these changes remains a challenge. Many established approaches are not applicable to humans because of their invasiveness. Functional renal magnetic resonance (MR) imaging offers an alternative assessment tool that could be used to evaluate renal morphology and function noninvasively and simultaneously. Thus, the purpose of this review is to illustrate the principle, application, and role of the techniques of functional renal MR imaging, including blood oxygen level-dependent imaging, arterial spin labeling, and diffusion-weighted MR imaging, in the management of AKI. The use of gadolinium in MR imaging may exacerbate renal impairment and cause nephrogenic systemic fibrosis. Therefore, dynamic contrast-enhanced MR imaging will not be discussed in this paper. PMID:26925411

  8. Functional brain imaging in irritable bowel syndrome with rectal balloon-distention by using fMRI

    OpenAIRE

    Yuan, Yao-Zong; Tao, Ran-Jun; Xu, Bin; Sun, Jing; Chen, Ke-Min; Miao, Fei; Zhang, Zhong-wei; Xu, Jia-Yu

    2003-01-01

    AIM: Irritable bowel syndrome (IBS) is characterized by abdominal pain and changes in stool habits. Visceral hypersensitivity is a key factor in the pathophysiology of IBS. The aim of this study was to examine the effect of rectal balloon-distention stimulus by blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) in visceral pain center and to compare the distribution, extent, and intensity of activated areas between IBS patients and normal controls.

  9. Functional MRI activity in the thalamus and occipital cortex of anesthetized dogs induced by monocular and binocular stimulation.

    OpenAIRE

    Willis, C K; Quinn, R P; McDonell, W M; Gati, J; Partlow, G; Vilis, T.

    2001-01-01

    The neuroanatomy of the mammalian visual system has received considerable attention through electrophysiological study of cats and non-human primates, and through neuroimaging of humans. Canine neuroanatomy, however, has received much less attention, limiting our understanding of canine vision and visual pathways. As an early step in applying blood oxygenation level dependant (BOLD) functional magnetic resonance imaging (fMRI) for veterinary use, we compared visual activity in the thalamus an...

  10. Effect of luminance contrast on BOLD-fMRI response in deaf and normal occipital visual cortex

    International Nuclear Information System (INIS)

    Objective: To examine the effect of luminance contrast stimulus by using blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) within deaf occipital visual cortex, and to compare the distribution, extent, and intensity of activated areas between deaf subjects and normal hearing subjects. Methods: Twelve deaf subjects (average age 16.5) and 15 normal hearing subjects (average age 23.7) were stimulated by 4 kinds of luminance contrast (0.7, 2.2, 50.0, 180.0 lm). The fMRI data were collected on GE 1.5 T Signa Horizon LX MRI system and analyzed by AFNI to generate the activation map. Results: Responding to all 4 kinds of stimulus luminance contrast, all deaf and normal subjects showed significant activations in occipital visual cortex. For both deaf and normal subjects, the number of activated pixels increased significantly with increasing luminance contrast (Fnormal = 4.27, P deaf = 6.41, P 0.05). The local mean activation level for all activated pixels remained constant with increasing luminance contrast. However, there was an increase in the mean activation level for those activated pixels common to all trials as the stimulus luminance contrast was increased, but no significant difference was found within them (Fnormal = 0.79, P > 0.05; Fdeaf = 1.6, P > 0.05). Conclusion: The effect of luminance contrast on occipital visual cortex of deaf is similar to but somewhat higher than that of normal hearing subjects. In addition, it also proved that fMRI is a feasible method in the study of the deaf visual cortex

  11. Brain magnetic resonance imaging with contrast dependent on blood oxygenation

    International Nuclear Information System (INIS)

    Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity

  12. Brain magnetic resonance imaging with contrast dependent on blood oxygenation

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, S.; Lee, T.M.; Kay, A.R.; Tank, D.W. (AT and T Bell Laboratories, Murray Hill, NJ (United States))

    1990-12-01

    Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity.

  13. Network structure of cerebral cortex shapes functional connectivity on multiple time scales

    Science.gov (United States)

    Honey, Christopher J.; Kötter, Rolf; Breakspear, Michael; Sporns, Olaf

    2007-01-01

    Neuronal dynamics unfolding within the cerebral cortex exhibit complex spatial and temporal patterns even in the absence of external input. Here we use a computational approach in an attempt to relate these features of spontaneous cortical dynamics to the underlying anatomical connectivity. Simulating nonlinear neuronal dynamics on a network that captures the large-scale interregional connections of macaque neocortex, and applying information theoretic measures to identify functional networks, we find structure–function relations at multiple temporal scales. Functional networks recovered from long windows of neural activity (minutes) largely overlap with the underlying structural network. As a result, hubs in these long-run functional networks correspond to structural hubs. In contrast, significant fluctuations in functional topology are observed across the sequence of networks recovered from consecutive shorter (seconds) time windows. The functional centrality of individual nodes varies across time as interregional couplings shift. Furthermore, the transient couplings between brain regions are coordinated in a manner that reveals the existence of two anticorrelated clusters. These clusters are linked by prefrontal and parietal regions that are hub nodes in the underlying structural network. At an even faster time scale (hundreds of milliseconds) we detect individual episodes of interregional phase-locking and find that slow variations in the statistics of these transient episodes, contingent on the underlying anatomical structure, produce the transfer entropy functional connectivity and simulated blood oxygenation level-dependent correlation patterns observed on slower time scales. PMID:17548818

  14. Neural responses to a modified Stroop paradigm in patients with complex chronic musculoskeletal pain compared to matched controls: an experimental functional magnetic resonance imaging study

    OpenAIRE

    Taylor, Ann M; Harris, Ashley D; Varnava, Alice; Phillips, Rhiannon; HUghes, Owen; Wilkes, Antony R.; Hall, Judith E; Wise, Richard G.

    2016-01-01

    Background Chronic musculoskeletal pain (CMSKP) is attentionally demanding, complex and multi-factorial; neuroimaging research in the population seen in pain clinics is sparse. A better understanding of the neural activity underlying attentional processes to pain related information compared to healthy controls may help inform diagnosis and management in the future. Methods Blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI) compared brain responses in patients...

  15. Luminance contrast of a visual stimulus modulates the BOLD response more than the cerebral blood flow response in the human brain.

    Science.gov (United States)

    Liang, Christine L; Ances, Beau M; Perthen, Joanna E; Moradi, Farshad; Liau, Joy; Buracas, Giedrius T; Hopkins, Susan R; Buxton, Richard B

    2013-01-01

    The blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI) depends on the evoked changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO(2)) in response to changes in neural activity. This response is strongly modulated by the CBF/CMRO(2) coupling relationship with activation, defined as n, the ratio of the fractional changes. The reliability of the BOLD signal as a quantitative reflection of underlying physiological changes depends on the stability of n in response to different stimuli. The effect of visual stimulus contrast on this coupling ratio was tested in 9 healthy human subjects, measuring CBF and BOLD responses to a flickering checkerboard at four visual contrast levels. The theory of the BOLD effect makes a robust prediction-independent of details of the model-that if the CBF/CMRO(2) coupling ratio n remains constant, then the response ratio between the lowest and highest contrast levels should be higher for the BOLD response than the CBF response because of the ceiling effect on the BOLD response. Instead, this response ratio was significantly lower for the BOLD response (BOLD response: 0.23 ± 0.13, mean ± SD; CBF response: 0.42 ± 0.18; p=0.0054). This data is consistent with a reduced dynamic range (strongest/weakest response ratio) of the CMRO(2) response (~1.7-fold) compared to that of the CBF response (~2.4-fold) as luminance contrast increases, corresponding to an increase of n from 1.7 at the lowest contrast level to 2.3 at the highest contrast level. The implication of these results for fMRI studies is that the magnitude of the BOLD response does not accurately reflect the magnitude of underlying physiological processes. PMID:22963855

  16. Mapping of cognitive functions in chronic intractable epilepsy: Role of fMRI

    Directory of Open Access Journals (Sweden)

    Kapil Chaudhary

    2014-01-01

    Full Text Available Background: Functional magnetic resonance imaging (fMRI, a non-invasive technique with high spatial resolution and blood oxygen level dependent (BOLD contrast, has been applied to localize and map cognitive functions in the clinical condition of chronic intractable epilepsy. Purpose: fMRI was used to map the language and memory network in patients of chronic intractable epilepsy pre- and post-surgery. Materials and Methods: After obtaining approval from the institutional ethics committee, six patients with intractable epilepsy with an equal number of age-matched controls were recruited in the study. A 1.5 T MR scanner with 12-channel head coil, integrated with audio-visual fMRI accessories was used. Echo planar imaging sequence was used for BOLD studies. There were two sessions in TLE (pre- and post-surgery. Results: In TLE patients, BOLD activation increased post-surgery in comparison of pre-surgery in inferior frontal gyrus (IFG, middle frontal gyrus (MFG, and superior temporal gyrus (STG, during semantic lexical, judgment, comprehension, and semantic memory tasks. Conclusion: Functional MRI is useful to study the basic concepts related to language and memory lateralization in TLE and guide surgeons for preservation of important brain areas during ATLR. This will help in understanding future directions for the diagnosis and treatment of such disease.

  17. Deep brain stimulation for Parkinson's disease dissociates mood and motor circuits: a functional MRI case study.

    Science.gov (United States)

    Stefurak, Taresa; Mikulis, David; Mayberg, Helen; Lang, Anthony E; Hevenor, Stephanie; Pahapill, Peter; Saint-Cyr, Jean; Lozano, Andres

    2003-12-01

    Behavioral disturbances have been reported with subthalamic (STN) deep brain stimulation (DBS) treatment in Parkinson's disease (PD). We report correlative functional imaging (fMRI) of mood and motor responses induced by successive right and left DBS. A 36-year-old woman with medically refractory PD and a history of clinically remitted depression underwent uncomplicated implantation of bilateral STN DBS. High-frequency stimulation of the left electrode improved motor symptoms. Unexpectedly, right DBS alone elicited several reproducible episodes of acute depressive dysphoria. Structural and functional magnetic resonance imaging (fMRI) imaging was carried out with sequential individual electrode stimulation. The electrode on the left was within the inferior STN, whereas the right electrode was marginally superior and lateral to the intended STN target within the Fields of Forel/zona incerta. fMRI image analysis (Analysis of Functional NeuroImages, AFNI) contrasting OFF versus ON stimulation identified significant lateralized blood oxygen level-dependent (BOLD) signal changes with DBS (P disturbance resolved spontaneously in 4 weeks despite identical stimulation parameters. Transient depressive mood induced by subcortical DBS stimulation was correlated with changes in mesolimbic cortical structures. This case provides new evidence supporting cortical segregation of motor and nonmotor cortico-basal ganglionic systems that may converge in close proximity at the level of the STN and the adjacent white matter tracts (Fields of Forel/zona incerta). PMID:14673888

  18. A Preliminary Study of Functional Brain Activation among Marijuana Users during Performance of a Virtual Water Maze Task

    Directory of Open Access Journals (Sweden)

    Jennifer Tropp Sneider

    2013-01-01

    Full Text Available Numerous studies have reported neurocognitive impairments associated with chronic marijuana use. Given that the hippocampus contains a high density of cannabinoid receptors, hippocampal-mediated cognitive functions, including visuospatial memory, may have increased vulnerability to chronic marijuana use. Thus, the current study examined brain activation during the performance of a virtual analogue of the classic Morris water maze task in 10 chronic marijuana (MJ users compared to 18 nonusing (NU comparison subjects. Imaging data were acquired using blood oxygen level-dependent (BOLD functional MRI at 3.0 Tesla during retrieval (hidden platform and motor control (visible platform conditions. While task performance on learning trials was similar between groups, MJ users demonstrated a deficit in memory retrieval. For BOLD fMRI data, NU subjects exhibited greater activation in the right parahippocampal gyrus and cingulate gyrus compared to the MJ group for the Retrieval-Motor Control contrast (NU > MJ. These findings suggest that hypoactivation in MJ users may be due to differences in the efficient utilization of neuronal resources during the retrieval of memory. Given the paucity of data on visuospatial memory function in MJ users, these findings may help elucidate the neurobiological effects of marijuana on brain activation during memory retrieval.

  19. A preliminary study of functional brain activation among marijuana users during performance of a virtual water maze task.

    Science.gov (United States)

    Sneider, Jennifer Tropp; Gruber, Staci A; Rogowska, Jadwiga; Silveri, Marisa M; Yurgelun-Todd, Deborah A

    2013-01-01

    Numerous studies have reported neurocognitive impairments associated with chronic marijuana use. Given that the hippocampus contains a high density of cannabinoid receptors, hippocampal-mediated cognitive functions, including visuospatial memory, may have increased vulnerability to chronic marijuana use. Thus, the current study examined brain activation during the performance of a virtual analogue of the classic Morris water maze task in 10 chronic marijuana (MJ) users compared to 18 non-using (NU) comparison subjects. Imaging data were acquired using blood oxygen-level dependent (BOLD) functional MRI at 3.0 Tesla during retrieval (hidden platform) and motor control (visible platform) conditions. While task performance on learning trials was similar between groups, MJ users demonstrated a deficit in memory retrieval. For BOLD fMRI data, NU subjects exhibited greater activation in the right parahippocampal gyrus and cingulate gyrus compared to the MJ group for the Retrieval - Motor control contrast (NU > MJ). These findings suggest that hypoactivation in MJ users may be due to differences in the efficient utilization of neuronal resources during the retrieval of memory. Given the paucity of data on visuospatial memory function in MJ users, these findings may help elucidate the neurobiological effects of marijuana on brain activation during memory retrieval. PMID:23951549

  20. To Evaluate the Damage of Renal Function in CIAKI Rats at 3T: Using ASL and BOLD MRI

    Directory of Open Access Journals (Sweden)

    Wen-bo Chen

    2015-01-01

    Full Text Available Purpose. To investigate noninvasive arterial spin-labeling (ASL and blood oxygen level-dependent imaging (BOLD sequences for measuring renal hemodynamics and oxygenation in contrast induced acute kidney injury (CIAKI rat. Materials and Methods. Thirteen SD rats were randomly grouped into CIAKI group and control group. Both ASL and BOLD sequences were performed at 24 h preinjection and at intervals of 0.5, 12, 24, 48, 72, and 96 h postinjection to assess renal blood flow (RBF and relative spin-spin relaxation rate (R2*, respectively. Results. For the CIAKI group, the value of RBF in the cortex (CO and outer medulla (OM of the kidney was significantly decreased (P<0.05 at 12–48 h and regressed to baseline level (P=NS at 72–96 h. In OM, the value of R2* was increased at 0.5–48 h (P<0.05 and not statistically significant (P=NS at 72 and 96 h. Conclusions. RBF in OM and CO and oxygen level in OM were decreased postinjection of CM. ASL combining BOLD can further identify the primary cause of the decrease of renal oxygenation in CIAKI. This approach provides means for noninvasive monitoring renal function during the first 4 days of CIAKI in clinical routine work.

  1. Functional MR study of a motor task and the Tower of London task at 1.0 T

    International Nuclear Information System (INIS)

    The use of functional magnetic resonance imaging (fMRI) for clinical applications and basic neuroscience is constantly increasing. The discussion about minimum performance requirement for a correct implementation of fMRI is still open, and one of the critical points is the magnetic field strength. We tested the feasibility of fMRI at 1.0 T during motor and cognitive tasks. Fourteen healthy subjects were scanned during a motor task and 12 while performing the Tower of London task. In the activated areas, the percentage signal change due to BOLD (blood oxygenation level dependent) contrast was analysed. To check basic image quality of the acquisition system we measured quality indices in a temporal series of images of a phantom. Motor and cognitive brain activations matched previous results obtained at higher field strengths. The mean percentage change over subjects in the motor task was in the range 1.3-2.6% for the primary motor area and 0.8-6.7% for the cerebellum. In the cognitive task, the mean percentage change over subjects was 0.7-1.2% for a frontal area and 0.6-2.8% for a parietal area. The percentage noise of the phantom temporal series was less than 0.4%. Percentage changes and signal to noise ratio, although lower than that obtained with high-field systems, allowed activation maps to be obtained in all subjects. (orig.)

  2. Measuring brain hemodynamic changes in a songbird: responses to hypercapnia measured with functional MRI and near-infrared spectroscopy

    Science.gov (United States)

    Vignal, C.; Boumans, T.; Montcel, B.; Ramstein, S.; Verhoye, M.; Van Audekerke, J.; Mathevon, N.; Van der Linden, A.; Mottin, S.

    2008-05-01

    Songbirds have been evolved into models of choice for the study of the cerebral underpinnings of vocal communication. Nevertheless, there is still a need for in vivo methods allowing the real-time monitoring of brain activity. Functional Magnetic Resonance Imaging (fMRI) has been applied in anesthetized intact songbirds. It relies on blood oxygen level-dependent (BOLD) contrast revealing hemodynamic changes. Non-invasive near-infrared spectroscopy (NIRS) is based on the weak absorption of near-infrared light by biological tissues. Time-resolved femtosecond white laser NIRS is a new probing method using real-time spectral measurements which give access to the local variation of absorbing chromophores such as hemoglobins. In this study, we test the efficiency of our time-resolved NIRS device in monitoring physiological hemodynamic brain responses in a songbird, the zebra finch (Taeniopygia guttata), using a hypercapnia event (7% inhaled CO2). The results are compared to those obtained using BOLD fMRI. The NIRS measurements clearly demonstrate that during hypercapnia the blood oxygen saturation level increases (increase in local concentration of oxyhemoglobin, decrease in deoxyhemoglobin concentration and total hemoglobin concentration). Our results provide the first correlation in songbirds of the variations in total hemoglobin and oxygen saturation level obtained from NIRS with local BOLD signal variations.

  3. Measuring brain hemodynamic changes in a songbird: responses to hypercapnia measured with functional MRI and near-infrared spectroscopy

    International Nuclear Information System (INIS)

    Songbirds have been evolved into models of choice for the study of the cerebral underpinnings of vocal communication. Nevertheless, there is still a need for in vivo methods allowing the real-time monitoring of brain activity. Functional Magnetic Resonance Imaging (fMRI) has been applied in anesthetized intact songbirds. It relies on blood oxygen level-dependent (BOLD) contrast revealing hemodynamic changes. Non-invasive near-infrared spectroscopy (NIRS) is based on the weak absorption of near-infrared light by biological tissues. Time-resolved femtosecond white laser NIRS is a new probing method using real-time spectral measurements which give access to the local variation of absorbing chromophores such as hemoglobins. In this study, we test the efficiency of our time-resolved NIRS device in monitoring physiological hemodynamic brain responses in a songbird, the zebra finch (Taeniopygia guttata), using a hypercapnia event (7% inhaled CO2). The results are compared to those obtained using BOLD fMRI. The NIRS measurements clearly demonstrate that during hypercapnia the blood oxygen saturation level increases (increase in local concentration of oxyhemoglobin, decrease in deoxyhemoglobin concentration and total hemoglobin concentration). Our results provide the first correlation in songbirds of the variations in total hemoglobin and oxygen saturation level obtained from NIRS with local BOLD signal variations

  4. Functional magnetic resonance imaging of the rat cerebellum during electrical stimulation of the fore- and hindpaw at 7 T

    Science.gov (United States)

    Peeters, Ronald; Verhoye, Marleen; Vos, Bart; De Schutter, Erik; Van der Linden, Anne-Marie

    1999-05-01

    Blood oxygenation level dependent contrast (BOLD) functional MRI responses at 7T were observed in the cerebellum of alpha- chloralose anesthetized rats in response to innocuous electrical stimulation of a forepaw or hindpaw. The responses were imaged in both coronal and sagittal slices which allowed for a clear delineation and localization of the observed activations. We demonstrate the validity of our fMRI protocol by imaging the responses in somatosensory cortex to the same stimuli and by showing a high level of reproducibility of the cerebellar responses. Widespread bilateral activations were found with mainly a patchy and medio-lateral band organization, more pronounced ipsilaterally. There was no overlap between the cerebellar activations caused by forepaw or hindpaw stimulation. Most remarkable was the overall horizontal organization of these responses: for both stimulation paradigms the patches and bands of activation were roughly positioned in either a cranial or caudal plane running antero-posteriorly through the whole cerebellum. This is the first fMRI study in the cerebellum of the rat. We relate our findings to the known projection patterns found with other techniques and to human fMRI studies. The horizontal organization found wasn't observed before in other studies using other techniques.

  5. Measuring brain hemodynamic changes in a songbird: responses to hypercapnia measured with functional MRI and near-infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vignal, C; Mathevon, N [ENES EA 3988, Universite Jean Monnet, Saint-Etienne (France); Boumans, T; Verhoye, M; Audekerke, J van; Linden, A van der [Bio-Imaging Laboratory, University of Antwerp, Antwerp (Belgium); Montcel, B; Ramstein, S; Mottin, S [Hubert Curien CNRS UMR 5516, Universite Jean Monnet, Saint-Etienne (France)], E-mail: Clementine.Vignal@univ-st-etienne.fr

    2008-05-21

    Songbirds have been evolved into models of choice for the study of the cerebral underpinnings of vocal communication. Nevertheless, there is still a need for in vivo methods allowing the real-time monitoring of brain activity. Functional Magnetic Resonance Imaging (fMRI) has been applied in anesthetized intact songbirds. It relies on blood oxygen level-dependent (BOLD) contrast revealing hemodynamic changes. Non-invasive near-infrared spectroscopy (NIRS) is based on the weak absorption of near-infrared light by biological tissues. Time-resolved femtosecond white laser NIRS is a new probing method using real-time spectral measurements which give access to the local variation of absorbing chromophores such as hemoglobins. In this study, we test the efficiency of our time-resolved NIRS device in monitoring physiological hemodynamic brain responses in a songbird, the zebra finch (Taeniopygia guttata), using a hypercapnia event (7% inhaled CO{sub 2}). The results are compared to those obtained using BOLD fMRI. The NIRS measurements clearly demonstrate that during hypercapnia the blood oxygen saturation level increases (increase in local concentration of oxyhemoglobin, decrease in deoxyhemoglobin concentration and total hemoglobin concentration). Our results provide the first correlation in songbirds of the variations in total hemoglobin and oxygen saturation level obtained from NIRS with local BOLD signal variations.

  6. Recent development in noninvasive brain activity measurement by functional magnetic resonance imaging (fMRI)

    International Nuclear Information System (INIS)

    fMRI (functional magnetic resonance imaging) is a non-invasive brain imaging technique with which the distribution of neural activity is estimated by measuring local blood flow changes. Blood-oxygenation-level-dependent (BOLD) method measures changes in the density of deoxidized hemoglobin in blood caused by blood flow changes, while other methods have been developed to measure the blood flow changes directly. Effort has been expended to realize a submillimeter spatial resolution by using higher static magnetic field. fMRI has been carried out with various mental tasks, and many important findings have been made on the localization of higher brain functions. (author)

  7. Effects of Image Contrast on Functional MRI Image Registration

    OpenAIRE

    Gonzalez-Castillo, Javier; Duthie, Kristen N.; Saad, Ziad S.; Chu, Carlton; Bandettini, Peter A.; Luh, Wen-Ming

    2012-01-01

    Lack of tissue contrast and existing inhomogeneous bias fields from multi-channel coils have the potential to degrade the output of registration algorithms; and consequently degrade group analysis and any attempt to accurately localize brain function. Non-invasive ways to improve tissue contrast in fMRI images include the use of low flip angles (FAs) well below the Ernst angle and longer repetition times (TR). Techniques to correct intensity inhomogeneity are also available in most mainstream...

  8. Functional MRI in human motor control studies and clinical applications

    International Nuclear Information System (INIS)

    Functional magnetic resonance imaging (fMRI) has been a useful tool for the noninvasive mapping of brain function associated with various motor and cognitive tasks. Because fMRI is based on the blood oxygenation level dependent (BOLD) effect, it does not directly record neural activity. With the fMRI technique, distinguishing BOLD signals creased by cortical projection neurons from those created by intracortical neurons appears to be difficult. Two major experimental designs are used in fMRI studies: block designs and event-related designs. Block-designed fMRI presupposes the steady state of regional cerebral blood flow and has been applied to examinations of brain activation caused by tasks requiring sustained or repetitive movements. By contrast, the more recently developed event-related fMRI with time resolution of a few seconds allows the mapping of brain activation associated with a single movement according to the transient aspects of the hemodynamic response. Increasing evidence suggests that multiple motor areas are engaged in a networked manner to execute various motor acts. In order to understand functional brain maps, it is important that one understands sequential and parallel organizations of anatomical connections between multiple motor areas. In fMRI studies of complex motor tasks, elementary parameters such as movement length, force, velocity, acceleration and frequency should be controlled, because inconsistency in those parameters may alter the extent and intensity of motor cortical activation, confounding interpretation of the findings obtained. In addition to initiation of movements, termination of movements plays an important role in the successful achievement of complex movements. Brain areas exclusively related to the termination of movements have been, for the first time, uncovered with an event-related fMRI technique. We propose the application of fMRI to the elucidation of the pathophysiology of movement disorders, particularly dystonia

  9. Brain Correlates of Self-Evaluation Deficits in Schizophrenia: A Combined Functional and Structural MRI Study.

    Directory of Open Access Journals (Sweden)

    Shuping Tan

    Full Text Available Self-evaluation plays an important role in adaptive functioning and is a process that is typically impaired in patients with schizophrenia. Underlying neural mechanisms for this dysfunction may be associated with manifested psychosis. However, the brain substrates underlying this deficit are not well known. The present study used brain blood oxygen level dependent (BOLD functional magnetic resonance imaging (fMRI and gray matter voxel-based morphometry to explore the functional and structural brain correlates of self-evaluation deficits in schizophrenia. Eighteen patients with schizophrenia and 17 healthy controls were recruited and asked to judge whether a set of personality-trait adjectives were appropriate for describing themselves, a familiar other, or whether the adjectives were of positive or negative valence. Patients had slower response times for negative trait attributions than controls did; responses to positive trait attributions were faster than those for negative traits among the patient group, while no differences were observed in the control group. Control subjects showed greater activation within the dorsal medial prefrontal cortex (dMPFC and the anterior cingulate cortex (ACC than the patient group during the self-evaluation > semantic positivity-evaluation contrast. Patients showed greater activation mainly within the posterior cingulate gyrus (PCC as compared to controls for the other-evaluation > semantic positivity-evaluation contrast. Furthermore, gray matter volume was reduced in the MPFC, temporal lobe, cuneus, and the dorsal lateral prefrontal cortex (DLPFC among the patient group when compared to controls. The present study adds to previous findings regarding self- and other-referential processing in schizophrenia, providing support for neurobiological models of self-reflection impairment.

  10. Does functional MRI detect activation in white matter? A review of emerging evidence, issues, and future directions

    OpenAIRE

    JodieReannaGawryluk; RyanD'Arcy; ErinLindsayMazerolle

    2014-01-01

    Functional magnetic resonance imaging (fMRI) is a non-invasive technique that allows for visualization of activated brain regions. Until recently, fMRI studies have focused on gray matter. There are two main reasons white matter fMRI remains controversial: (1) the blood oxygen level dependent (BOLD) fMRI signal depends on cerebral blood flow and volume, which are lower in white matter than gray matter and (2) fMRI signal has been associated with post-synaptic potentials (mainly localized in g...

  11. Assessment of Alzheimer’s Disease Risk with Functional Magnetic Resonance Imaging: An Arterial Spin Labeling Study

    OpenAIRE

    Bangen, Katherine J.; Restom, Khaled; Liu, Thomas T.; Wierenga, Christina E.; Jak, Amy J.; Salmon, David P.; Bondi, Mark W.

    2012-01-01

    Functional magnetic resonance imaging (fMRI) of older adults at risk for Alzheimer’s disease (AD) by virtue of their cognitive (i.e., mild cognitive impairment [MCI]) and/or genetic (i.e., apolipoprotein E [APOE] ε4 allele) status demonstrate divergent brain response patterns during memory encoding across studies. Using arterial spin labeling MRI, we examined the influence of AD risk on resting cerebral blood flow (CBF) as well as the CBF and blood oxygenation level dependent (BOLD) signal re...

  12. CONTRAST

    DEFF Research Database (Denmark)

    Kristensen, Thomas Krogsgaard

    2007-01-01

    Dette er en afrapportering fra den årlige CONTRAST workshop, der i 2007 blev afholdt i Yaoundé, Cameroon.......Dette er en afrapportering fra den årlige CONTRAST workshop, der i 2007 blev afholdt i Yaoundé, Cameroon....

  13. Development of functional imaging in the human brain (fMRI); the University of Minnesota experience.

    Science.gov (United States)

    Uğurbil, Kâmil

    2012-08-15

    The human functional magnetic resonance imaging (fMRI) experiments performed in the Center for Magnetic Resonance Research (CMRR), University of Minnesota, were planned between two colleagues who had worked together previously in Bell Laboratories in the late nineteen seventies, namely myself and Seiji Ogawa. These experiments were motivated by the Blood Oxygenation Level Dependent (BOLD) contrast developed by Seiji. We discussed and planned human studies to explore imaging human brain activity using the BOLD mechanism on the 4 Tesla human system that I was expecting to receive for CMRR. We started these experiments as soon as this 4 Tesla instrument became marginally operational. These were the very first studies performed on the 4 Tesla scanner in CMRR; had the scanner become functional earlier, they would have been started earlier as well. We were aware of the competing effort at the Massachusetts General Hospital (MGH) and we knew that they had been informed of our initiative in Minneapolis to develop fMRI. We had positive results certainly by August 1991 annual meeting of the Society of Magnetic Resonance in Medicine (SMRM). I believe, however, that neither the MGH colleagues nor us, at the time, had enough data and/or conviction to publish these extraordinary observations; it took more or less another six months or so before the papers from these two groups were submitted for publication within five days of each other to the Proceedings of the National Academy of Sciences, USA, after rejection by Nature in our case. Thus, fMRI was achieved independently and at about the same time at MGH, in an effort credited largely to Ken Kwong, and in CMRR, University of Minnesota in an effort led by myself and Seiji Ogawa. PMID:22342875

  14. Blood oxygenation level-dependent magnetic resonance imaging during carbogen breathing: differentiation between prostate cancer and benign prostate hyperplasia and correlation with vessel maturity

    OpenAIRE

    Wang, Bin

    2016-01-01

    Ningning Di,1,2,* Ning Mao,3,* Wenna Cheng,4 Haopeng Pang,1 Yan Ren,1 Ning Wang,2 Xinjiang Liu,2 Bin Wang5 1Department of Radiology, Affiliated Huashan Hospital of Fudan University, Shanghai, 2Department of Radiology, Binzhou Medical University Affiliated Hospital, Binzhou, 3Department of Radiology, Yantai Yuhangding Hospital, Yantai, 4Department of Pharmacy, Binzhou Medical University Affiliated Hospital, Binzhou, 5Department of Medical Imaging and Nuclear Medicine, Binzhou Medical Universi...

  15. Assessing the end-organ in peripheral arterial occlusive disease—from contrast—enhanced ultrasound to blood-oxygen-level-dependent MR imaging

    OpenAIRE

    Aschwanden, Markus; Partovi, Sasan; Jacobi, Bjoern; Fergus, Nathan; Schulte, Anja-Carina; Robbin, Mark R; Bilecen, Deniz; Staub, Daniel

    2014-01-01

    Peripheral arterial occlusive disease (PAOD) is a result of atherosclerotic disease which is currently the leading cause of morbidity and mortality in the western world. Patients with PAOD may present with intermittent claudication or symptoms related to critical limb ischemia. PAOD is associated with increased mortality rates. Stenoses and occlusions are usually detected by macrovascular imaging, including ultrasound and cross-sectional methods. From a pathophysiological view these stenoses ...

  16. Regional placental blood oxygen level dependent (BOLD) changes with gestational age in normally developing pregnancies using long duration R2* mapping in utero

    Science.gov (United States)

    Dighe, Manjiri; Kim, Yun Jung; Seshamani, Sharmishtaa; Blazejewska, Ania I.; Mckown, Susan; Caucutt, Jason; Gatenby, Christopher; Studholme, Colin

    2016-03-01

    The aim of this study was to examine the use of R2* mapping in maternal and fetal sub-regions of the placenta with the aim of providing a reference for blood oxygenation levels during normative development. There have been a number of MR relaxation studies of placental tissues in-utero, but none have reported R2* value changes with age, or examined differences in sub-regions of the placenta. Here specialized long-duration Multi-frame R2* imaging was used to create a stable estimate for R2* values in different placental regions in healthy pregnant volunteers not imaged for clinical reasons. 27 subjects were recruited and scanned up to 3 times during their pregnancy. A multi-slice dual echo EPI based BOLD acquisition was employed and repeated between 90 and 150 times over 3 to 5 minutes to provide a high accuracy estimate of the R2* signal level. Acquisitions were also repeated in 13 cases within a visit to evaluate reproducibility of the method in a given subject. Experimental results showed R2* measurements were highly repeatable within a visit with standard deviation of (0.76). Plots of all visits against gestational age indicated clear correlations showing decreases in R2* with age. This increase was consistent was also consistent over time in multiple visits of the same volunteer during their pregnancy. Maternal and fetal regional changes with gestational age followed the same trend with increase in R2* over the gestational age.

  17. Is the prefrontal cortex necessary for establishing cognitive sets?

    DEFF Research Database (Denmark)

    Rowe, James B; Sakai, Katsuyuki; Lund, Torben E;

    2007-01-01

    regional task set activity during the instruction delay, as evidenced by sustained changes in the blood oxygenation level-dependent signal in caudal frontal regions. However, in contrast to healthy controls, they were less able to maintain functional connectivity among the surviving task-related brain...

  18. Multiparametric functional nuclear magnetic resonance imaging shows alterations associated with plasmid electro transfer in mouse skeletal muscle

    International Nuclear Information System (INIS)

    In vivo gene electro transfer is frequently used in preclinical gene therapy. Many studies have attempted to optimize protocols efficiency at the same time as reducing muscle damage. Most of them have reported histological evidence of muscle degeneration and completion of regeneration within 15 days. The functional consequences have rarely been addressed, which may reflect the lack of appropriate techniques. Yet, it is important to characterize the changes induced by the procedure itself because it may interfere with therapy. We used multiparametric functional (mpf)-nuclear magnetic resonance (NMR) imaging to evaluate mice hindlimb muscle after electro transfer of an empty plasmid. NMR experiments were performed in a 4 T Bruker magnet. Arterial spin labeling imaging of perfusion and blood oxygenation level dependent contrast and 31P spectroscopy of phosphocreatine kinetics and pH were simultaneously acquired from the mice hindlimb during 2 min of electrically stimulated exercise and recovery. After 15 days, hindlimb cross-sectional area decreased by 10% compared to control mice. Specific force-time integral and end-exercise pH were identical in both groups, whereas oxidative capacities increased. Perfusion values doubled, and oxygenation significantly decreased. Histology revealed: (i) degeneration/regeneration; (ii) a decrease in type IIb fibers and an increase in type I and IIa fibers; and (iii) increased capillary density. In this model, loss in muscle mass was accompanied by important alterations of perfusion and bio-energetics. Fifteen days after electro transfer, this was correlated with fiber type shift, capillary bed remodeling and degeneration/regeneration. mpf-NMR provides new insights into the functional consequences of standard electro transfer and represents a powerful tool for optimization and longitudinal assessment of preclinical gene therapy protocols. (authors)

  19. Video Quality Assessment Using Spatio-Velocity Contrast Sensitivity Function

    Science.gov (United States)

    Hirai, Keita; Tumurtogoo, Jambal; Kikuchi, Ayano; Tsumura, Norimichi; Nakaguchi, Toshiya; Miyake, Yoichi

    Due to the development and popularization of high-definition televisions, digital video cameras, Blu-ray discs, digital broadcasting, IP television and so on, it plays an important role to identify and quantify video quality degradations. In this paper, we propose SV-CIELAB which is an objective video quality assessment (VQA) method using a spatio-velocity contrast sensitivity function (SV-CSF). In SV-CIELAB, motion information in videos is effectively utilized for filtering unnecessary information in the spatial frequency domain. As the filter to apply videos, we used the SV-CSF. It is a modulation transfer function of the human visual system, and consists of the relationship among contrast sensitivities, spatial frequencies and velocities of perceived stimuli. In the filtering process, the SV-CSF cannot be directly applied in the spatial frequency domain because spatial coordinate information is required when using velocity information. For filtering by the SV-CSF, we obtain video frames separated in spatial frequency domain. By using velocity information, the separated frames with limited spatial frequencies are weighted by contrast sensitivities in the SV-CSF model. In SV-CIELAB, the criteria are obtained by calculating image differences between filtered original and distorted videos. For the validation of SV-CIELAB, subjective evaluation experiments were conducted. The subjective experimental results were compared with SV-CIELAB and the conventional VQA methods such as CIELAB color difference, Spatial-CIELAB, signal to noise ratio and so on. From the experimental results, it was shown that SV-CIELAB is a more efficient VQA method than the conventional methods.

  20. Limbic Activity Modulation Guided by Functional Magnetic Resonance Imaging-Inspired Electroencephalography Improves Implicit Emotion Regulation.

    Science.gov (United States)

    Keynan, Jackob N; Meir-Hasson, Yehudit; Gilam, Gadi; Cohen, Avihay; Jackont, Gilan; Kinreich, Sivan; Ikar, Limor; Or-Borichev, Ayelet; Etkin, Amit; Gyurak, Anett; Klovatch, Ilana; Intrator, Nathan; Hendler, Talma

    2016-09-15

    The amygdala has a pivotal role in processing traumatic stress; hence, gaining control over its activity could facilitate adaptive mechanism and recovery. To date, amygdala volitional regulation could be obtained only via real-time functional magnetic resonance imaging (fMRI), a highly inaccessible procedure. The current article presents high-impact neurobehavioral implications of a novel imaging approach that enables bedside monitoring of amygdala activity using fMRI-inspired electroencephalography (EEG), hereafter termed amygdala-electrical fingerprint (amyg-EFP). Simultaneous EEG/fMRI indicated that the amyg-EFP reliably predicts amygdala-blood oxygen level-dependent activity. Implementing the amyg-EFP in neurofeedback demonstrated that learned downregulation of the amyg-EFP facilitated volitional downregulation of amygdala-blood oxygen level-dependent activity via real-time fMRI and manifested as reduced amygdala reactivity to visual stimuli. Behavioral evidence further emphasized the therapeutic potential of this approach by showing improved implicit emotion regulation following amyg-EFP neurofeedback. Additional EFP models denoting different brain regions could provide a library of localized activity for low-cost and highly accessible brain-based diagnosis and treatment. PMID:26996601

  1. Functional MRI of the cervical spinal cord on 1.5 T with fingertapping: to what extent is it feasible?

    International Nuclear Information System (INIS)

    Until recently, functional magnetic resonance imaging (fMRI) with blood oxygen level-dependent (BOLD) contrast, was mainly used to study brain physiology. The activation signal measured with fMRI is based upon the changes in the concentration of deoxyhaemoglobin that arise from an increase in blood flow in the vicinity of neuronal firing. Technical limitations have impeded such research in the human cervical spinal cord. The purpose of this investigation was to determine whether a reliable fMRI signal can be elicited from the cervical spinal cord during fingertapping, a complex motor activity. Furthermore, we wanted to determine whether the fMRI signal could be spatially localized to the particular neuroanatomical location specific for this task. A group of 12 right-handed healthy volunteers performed the complex motor task of fingertapping with their right hand. T2*-weighted gradient-echo echo-planar imaging on a 1.5-T clinical unit was used to image the cervical spinal cord. Motion correction was applied. Cord activation was measured in the transverse imaging plane, between the spinal cord levels C5 and T1. In all subjects spinal cord responses were found, and in most of them on the left and the right side. The distribution of the activation response showed important variations between the subjects. While regions of activation were distributed throughout the spinal cord, concentrated activity was found at the anatomical location of expected motor innervation, namely nerve root C8, in 6 of the 12 subjects. fMRI of the human cervical spinal cord on an 1.5-T unit detects neuronal activity related to a complex motor task. The location of the neuronal activation (spinal cord segment C5 through T1 with a peak on C8) corresponds to the craniocaudal anatomical location of the neurons that activate the muscles in use. (orig.)

  2. Continuous representation of human portraits and natural scenery in human ventral temporal cortex:evidence from functional magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    肖壮伟; 林冲宇; 罗小景; 黄芳梅; 庄伟端; 李俊雄; 翁旭初; 吴仁华

    2004-01-01

    Background Functional magnetic resonance imaging (fMRI) has become a powerful tool for tracking human brain activity in vivo. This technique is mainly based on blood oxygenation level dependence (BOLD) contrast. In the present study, we employed this newly developed technique to characterize the neural representations of human portraits and natural sceneries in the human brain.Methods Nine subjects were scanned with a 1.5 T magnetic resonance imaging (MRI) scanner using gradient-recalled echo and echo-planar imaging (GRE-EPI) pulse sequence while they were visually presented with 3 types of white-black photographs: natural scenery, human portraits, and scrambled nonsense pictures. Multiple linear regression was used to identify brain regions responding preferentially to each type of stimulus and common regions for both human portraits and natural scenery. The relative contributions of each type of stimulus to activation in these regions were examined using linear combinations of a general linear test.Results Multiple linear regression analysis revealed two distinct but adjacent regions in both sides of the ventral temporal cortex. The medial region preferentially responded to natural scenery, whereas the lateral one preferentially responded to the human portraits. The general linear test further revealed a distribution gradient such that a change from portraits to scenes shifted areas of activation from lateral to medial.Conclusions The boundary between portrait-associated and scenery-associated areas is not as clear as previously demonstrated. The representations of portraits and scenes in ventral temporal cortex appear to be continuous and overlap.

  3. Effect of ischemic preconditioning in skeletal muscle measured by functional magnetic resonance imaging and spectroscopy: a randomized crossover trial

    Directory of Open Access Journals (Sweden)

    Bartko Johann

    2011-06-01

    Full Text Available Abstract Background Nuclear magnetic resonance (NMR imaging and spectroscopy have been applied to assess skeletal muscle oxidative metabolism. Therefore, in-vivo NMR may enable the characterization of ischemia-reperfusion injury. The goal of this study was to evaluate whether NMR could detect the effects of ischemic preconditioning (IPC in healthy subjects. Methods Twenty-three participants were included in two randomized crossover protocols in which the effects of IPC were measured by NMR and muscle force assessments. Leg ischemia was administered for 20 minutes with or without a subsequent impaired reperfusion for 5 minutes (stenosis model. IPC was administered 4 or 48 hours prior to ischemia. Changes in 31phosphate NMR spectroscopy and blood oxygen level-dependent (BOLD signals were recorded. 3-Tesla NMR data were compared to those obtained for isometric muscular strength. Results The phosphocreatine (PCr signal decreased robustly during ischemia and recovered rapidly during reperfusion. In contrast to PCr, the recovery of muscular strength was slow. During post-ischemic stenosis, PCr increased only slightly. The BOLD signal intensity decreased during ischemia, ischemic exercise and post-ischemic stenosis but increased during hyperemic reperfusion. IPC 4 hours prior to ischemia significantly increased the maximal PCr reperfusion signal and mitigated the peak BOLD signal during reperfusion. Conclusions Ischemic preconditioning positively influenced muscle metabolism during reperfusion; this resulted in an increase in PCr production and higher oxygen consumption, thereby mitigating the peak BOLD signal. In addition, an impairment of energy replenishment during the low-flow reperfusion was detected in this model. Thus, functional NMR is capable of characterizing changes in reperfusion and in therapeutic interventions in vivo. Trial Registration ClinicalTrials.gov: NCT00883467

  4. Visualization and quality assessment of the contrast transfer function estimation.

    Science.gov (United States)

    Sheth, Lisa K; Piotrowski, Angela L; Voss, Neil R

    2015-11-01

    The contrast transfer function (CTF) describes an undesirable distortion of image data from a transmission electron microscope. Many users of full-featured processing packages are often new to electron microscopy and are unfamiliar with the CTF concept. Here we present a common graphical output to clearly demonstrate the CTF fit quality independent of estimation software. Separately, many software programs exist to estimate the four CTF parameters, but their results are difficult to compare across multiple runs and it is all but impossible to select the best parameters to use for further processing. A new measurement is presented based on the correlation falloff of the calculated CTF oscillations against the normalized oscillating signal of the data, called the CTF resolution. It was devised to provide a robust numerical quality metric of every CTF estimation for high-throughput screening of micrographs and to select the best parameters for each micrograph. These new CTF visualizations and quantitative measures will help users better assess the quality of their CTF parameters and provide a mechanism to choose the best CTF tool for their data. PMID:26080023

  5. High speed functional magnetic resonance imaging

    CERN Document Server

    Gibson, A M

    2002-01-01

    The work in this thesis has been undertaken by the except where indicated by reference, within the Magnetic Resonance Centre at the University of Nottingham during the period from October 1998 to October 2001. This thesis documents the implementation and application of a novel high-speed imaging technique, the multi-slice, echo shifted, echo planar imaging technique. This was implemented on the Nottingham 3 T imaging system, for functional magnetic resonance imaging. The technique uses echo shifting over the slices in a multi-slice echo planar imaging acquisition scheme, making the echo time longer than the repetition time per slice. This allows for rapid volumar sampling of the blood oxygen level dependent effect in the human brain. The new high-speed technique was used to investigate the variability of measuring the timing differences between haemodynamic responses, at the same cortical location, to simple cued motor tasks. The technique was also used in an investigation into motor cortex functional connect...

  6. Functional magnetic resonance imaging of the primary motor cortex in humans: response to increased functional demands

    Indian Academy of Sciences (India)

    S Khushu; S S Kumaran; R P Tripathi; A Gupta; P C Jain; V Jain

    2001-06-01

    Functional magnetic resonance imaging (fMRI) studies have been performed on 20 right handed volunteers at 1.5 Tesla using echo planar imaging (EPI) protocol. Index finger tapping invoked localized activation in the primary motor area. Consistent and highly reproducible activation in the primary motor area was observed in six different sessions of a volunteer over a period of one month. Increased tapping rate resulted in increase in the blood oxygenation level dependent (BOLD) signal intensity as well as the volume/area of activation (pixels) in the contralateral primary motor area up to tapping rate of 120 taps/min (2 Hz), beyond which it saturates. Activation in supplementary motor area was also observed. The obtained results are correlated to increased functional demands.

  7. Measurement on Modulation Transfer Function Under Different Contrasts

    Directory of Open Access Journals (Sweden)

    Wang Chi-zhong

    2013-02-01

    Full Text Available Aiming at the effect of environment to MTF measurement, the MTF measurent at different contrasts is presented. In order to get different contrasts, two integrating spheres are used to illuminate the face and back of the test target uniformly. The target luminance and background luminance of the test target are regulated by luminance control parts conveniently. The MTF measurement system is designed and developed. Many experimental results of show that the luminance differences between the values by the system and those by L88 standard level luminance meter are within ±0.3 cd/m2 so that the MTF measurement precision can be ensured. MTFs of Sony camera and Cannon camera at different contrasts are measured. The measurement values imply that MTFs at different contrasts can evaluate the imaging quality fully and objectively. This study provides an effective method to assess the imaging quality of visible imaging systems.  

  8. Contrast sensitivity functions for road visibility estimation in digital images

    OpenAIRE

    JOULAN, Karine; Hautiere, Nicolas; Bremond, Roland

    2011-01-01

    Automotive lighting systems are designed in order to provide the driver enough visibility, day and night, whatever the weather. In road lighting practice, an object of a fixed size in a simple scene is considered as visible if the contrast between its luminance and its background luminance is higher than a threshold contrast. This ratio is denoted VL (Visibility Level). We propose a framework in order to compute the VL of objects in the road scene from an onboard camera sensor. This framework...

  9. Clinical applications of functional MRI in epilepsy

    International Nuclear Information System (INIS)

    The role of functional MRI (fMRI) in the presurgical evaluation of patients with intractable epilepsy is being increasingly recognized. Real-time fMRI is an easily performable diagnostic technique in the clinical setting. It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively. Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized. This review article describes the biophysical basis of blood-oxygen-level-dependent (BOLD) fMRI and the methodology adopted, including the design, paradigms, the fMRI setup, and data analysis. Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy. Finally, the special issues involved in fMRI of epilepsy patients and the various challenges of clinical fMRI are detailed

  10. Contrasting the crospovidones functionality as excipients for direct compression

    Directory of Open Access Journals (Sweden)

    Daniel García Ramírez

    2015-03-01

    Full Text Available Specific values of technological properties of excipients allow the establishment of numerical parameters to define and compare their functionality. This study investigates the functionality of Polyplasdones XL and XL10. Parameters studied included tablet disintegration profiles, compactibility profiles and powder flow. The results allowed the establishment of quantitative surrogate functionalities of technological performance, such as absolute number, and as a value relative to the known microcrystalline cellulose type 102. Moreover, the establishment of an explicit functionality to improve the technological performance of two diluents and a model drug was investigated, as was setting up of these functionalities, as quantitative values, to determine the input variables of each material and its probable functionality in a drug product. Disintegration times of pure Polyplasdone XL and its admixtures were around half that of Polyplasdone XL10. The improvement in tablet compactibility was 25-50% greater for Polyplasdone XL10 than Polyplasdone XL. Crospovidones proportions of up to 10% have little effect on the flow properties of other powders, although pure Polyplasdone XL10 and its admixtures display compressibility indexes about 20% greater than Polyplasdone XL. The observed results are in line with a smaller particle size of Polyplasdone XL10 compared to Polyplasdone XL.

  11. Amygdala activity can be modulated by unexpected chord functions during music listening.

    Science.gov (United States)

    Koelsch, Stefan; Fritz, Thomas; Schlaug, Gottfried

    2008-12-01

    Numerous earlier studies have investigated the cognitive processing of musical syntax with regular and irregular chord sequences. However, irregular sequences may also be perceived as unexpected, and therefore have a different emotional valence than regular sequences. We provide behavioral data showing that irregular chord functions presented in chord sequence paradigms are perceived as less pleasant than regular sequences. A reanalysis of functional MRI data showed increased blood oxygen level-dependent signal changes bilaterally in the amygdala in response to music-syntactically irregular (compared with regular) chord functions. The combined data indicate that music-syntactically irregular events elicit brain activity related to emotional processes, and that, in addition to intensely pleasurable music or highly unpleasant music, single chord functions can also modulate amygdala activity. PMID:19050462

  12. Resting cerebral metabolism correlates with skin conductance and functional brain activation during fear conditioning.

    Science.gov (United States)

    Linnman, Clas; Zeidan, Mohamed A; Pitman, Roger K; Milad, Mohammed R

    2012-02-01

    We investigated whether resting brain metabolism can be used to predict autonomic and neuronal responses during fear conditioning in 20 healthy humans. Regional cerebral metabolic rate for glucose was measured via positron emission tomography at rest. During conditioning, autonomic responses were measured via skin conductance, and blood oxygen level dependent signal was measured via functional magnetic resonance imaging. Resting dorsal anterior cingulate metabolism positively predicted differentially conditioned skin conductance responses. Midbrain and insula resting metabolism negatively predicted midbrain and insula functional reactivity, while dorsal anterior cingulate resting metabolism positively predicted midbrain functional reactivity. We conclude that resting metabolism in limbic areas can predict some aspects of psychophysiological and neuronal reactivity during fear learning. PMID:22207247

  13. Prevention of radiographic-contrast-agent-induced reductions in renal function by acetylcysteine

    DEFF Research Database (Denmark)

    Tepel, Martin; van der Giet, M; Schwarzfeld, C;

    2000-01-01

    Radiographic contrast agents can cause a reduction in renal function that may be due to reactive oxygen species. Whether the reduction can be prevented by the administration of antioxidants is unknown.......Radiographic contrast agents can cause a reduction in renal function that may be due to reactive oxygen species. Whether the reduction can be prevented by the administration of antioxidants is unknown....

  14. Effects of contrast media on renal graft function and survival after cerebral angiography of cadaveric donors

    International Nuclear Information System (INIS)

    The effects of intravascularly administered ionic contrast media on renal graft function and survival were retrospectively evaluated in 211 recipients of cadaveric renal transplants. The renal grafts were explanted from the donors within 24 hours (mean 16 hours) after cerebral angiography. There were no differences in renal function of graft survival between those exposed and those not exposed to contrast media before nephrectomy. (orig.)

  15. Contrasting Strategies of Tree Function in a Seasonal Amazon Rainforest

    Science.gov (United States)

    Ivanov, V. Y.; Oliveira, R.; Agee, E.; Brum, M., Jr.; Saleska, S. R.; Fatichi, S.; Ewing, G.

    2015-12-01

    The increased frequency and severity of drought conditions in the Amazon Basin region have emphasized the question of rainforest vulnerability and resilience to heat and drought-induced stresses. However, what emerges from much research is that the impacts of droughts, essential controlling factors of the rainforest function, and variability of tree-scale strategies are yet to be fully understood. We present here a preliminary analysis of hydraulic relations of a seasonal Amazon rainforest using a set of ecohydrologic data collected through the GoAmazon project over dry and wet seasons. Expressions of different hydraulic strategies are identified that convey different implications for tree resilience during short- (diurnal) and longer-term (seasonal) stress periods. These hydraulic strategies appear to be inter-related with the tree growth and non-structural carbohydrate dynamics, contributing to the understanding of trait coordination at the whole-plant scale. Integration of individual responses is conducted over a range of wood density and exposure conditions. The results of this research thus shed light on the implication of variations in the rainforest function for future stresses, vital for predictive models of ecosystem dynamics of next generation.

  16. Contrastive studies of potential energy functions of some diatomic molecules

    Science.gov (United States)

    Abdallah, Hassan H.; Abdullah, Hewa Y.

    2016-03-01

    It was proposed that iron hydride, FeH, would be formed only on grains at the clouds through the reaction of the adsorbed H atoms or H2 molecules with the adsorbed Fe atoms on the grains. The importance of FeH in Astrophysics presents an additional motivation to study its energetic, spectroscopic constants and Potential Energy Curves. The structural optimization for ground state of FeH was calculated by different theoretical methods, namely, Hartree-Fock (HF), the density functional theory (DFT), B3LYP, MP2 method and QCISD(T) methods and compared with available data from the literature. The single ionized forms, cation and anion, were also obtained at the same level of calculations. Charges, dipole moment, geometrical parameters, molecular orbital energies and spectroscopic parameters were calculated and reported. In addition, the molecular ionization potential, electron affinity and dissociation energy were investigated.

  17. Isoprene function in two contrasting poplars under salt and sunflecks.

    Science.gov (United States)

    Behnke, K; Ghirardo, A; Janz, D; Kanawati, B; Esperschütz, J; Zimmer, I; Schmitt-Kopplin, P; Niinemets, Ü; Polle, A; Schnitzler, J P; Rosenkranz, M

    2013-06-01

    In the present study, biogenic volatile organic compound (BVOC) emissions and photosynthetic gas exchange of salt-sensitive (Populus x canescens (Aiton) Sm.) and salt-tolerant (Populus euphratica Oliv.) isoprene-emitting and non-isoprene-emitting poplars were examined under controlled high-salinity and high-temperature and -light episode ('sunfleck') treatments. Combined treatment with salt and sunflecks led to an increased isoprene emission capacity in both poplar species, although the photosynthetic performance of P. × canescens was reduced. Indeed, different allocations of isoprene precursors between the cytosol and the chloroplast in the two species were uncovered by means of (13)CO2 labeling. Populus × canescens leaves, moreover, increased their use of 'alternative' carbon (C) sources in comparison with recently fixed C for isoprene biosynthesis under salinity. Our studies show, however, that isoprene itself does not have a function in poplar survival under salt stress: the non-isoprene-emitting leaves showed only a slightly decreased photosynthetic performance compared with wild type under salt treatment. Lipid composition analysis revealed differences in the double bond index between the isoprene-emitting and non-isoprene-emitting poplars. Four clear metabolomics patterns were recognized, reflecting systemic changes in flavonoids, sterols and C fixation metabolites due to the lack/presence of isoprene and the absence/presence of salt stress. The studies were complemented by long-term temperature stress experiments, which revealed the thermotolerance role of isoprene as the non-isoprene-emitting leaves collapsed under high temperature, releasing a burst of BVOCs. Engineered plants with a low isoprene emission potential might therefore not be capable of resisting high-temperature episodes. PMID:23532135

  18. The affects of contrast medium on renal function in selective coronary angiography and intervention

    International Nuclear Information System (INIS)

    Selective coronary angiography and intervention with injection of contrast medium into the coronary arteries has become very common in dealing with coronary cardiac diseases. The excretion of contrast medium through kidneys may lead to acute renal functional insufficiency, especially for those suffering from chronic nephropathy, diabetes and cardiac functional disorder to form the so called 'contrast medium nephropathy' which is considered as the number second drug induced acute renal functional failure. Although routine preventive measure including low osmotic contrast medium and fine hydrotherapy have been taken, 14% incidences still occur with renal functional damage. The majority could be reversible but the minority needs emergent hemodialysis or even with persistent renal functional damage in a few ones. (authors)

  19. Functional MRI Examination of Visual Pathways in Patients with Unilateral Optic Neuritis

    International Nuclear Information System (INIS)

    The relations between brain areas involved in vision were explored in 8 patients with unilateral acute optic neuritis using functional magnetic resonance imaging (f MRI) and diffusion tensor imaging (DTI). In all patients monocular stimulation of affected and unaffected eye elicited significantly different activation foci in the primary visual cortex (V1), whereas the foci evoked in the middle temporal visual area (area V5) were similar in size and in delay of blood-oxygen-level-dependent response. DTI analysis documented lower white matter anisotropy values and reduced fibre reconstruction in the affected compared with the unaffected optic nerves. The preserved activation of area V5 observed in all our patients is an interesting finding that suggests the notion of a different sensitivity of the optic pathways to inflammatory changes.

  20. Localization of pilomotor seizure demonstrated by electroencephalography /functional magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Yao Zhiping

    2010-12-01

    Full Text Available We report the first case of a pilomotor seizure detected by electroencephalography /functional magnetic resonance imaging (EEG/fMRI. An adult woman presented with history of bouts of gooseflesh feeling and poilomotor activity in the left leg following viral encephalitis. 24-hour video-EEG and simultaneous EEG during fMRI revealed ictal discharges in the right parietal and temporal lobes. Associated blood oxygen level- dependent (BOLD activations were found mainly in the right parietal region. The result represents a different generator of pilomotor seizure compared to prior reports. We suggests that the feeling of gooseflesh could be the core ictal symptom and a direct pathway from the sensory cortex to the lower autonomic system may exist bypassing the classic cerebral autonomic center.

  1. A functional MRI study of somatotopic representation of somatosensory stimulation in the cerebellum

    Energy Technology Data Exchange (ETDEWEB)

    Takanashi, M.; Abe, K.; Yanagihara, T.; Sakoda, S. [Dept. of Neurology D4, Osaka Univ. Graduate School of Medicine, Suita City, Osaka (Japan); Tanaka, H.; Hirabuki, N.; Nakamura, H.; Fujita, N. [Dept. of Radiology, Osaka Univ. Graduate School of Medicine, Suita City, Osaka (Japan)

    2003-03-01

    Somatotopic representation in the cerebral cortex of somatosensory stimulation has been widely reported, but that in the cerebellum has not. We investigated the latter in the human cerebellum by functional MRI (fMRI). Using a 1.5 tesla imager, we obtained multislice blood oxygen level-dependent fMRI with single-shot gradient-echo echoplanar imaging in seven right-handed volunteers during electrical stimulation of the left index finger and big toe. In the anterior and posterior cerebellum, activated pixels for the index finger were separate from those for the toe. This suggests that somatosensory stimulation of different parts of the body may involve distinct areas of in the cerebellum as well as the cerebral cortex. (orig.)

  2. A functional MRI study of somatotopic representation of somatosensory stimulation in the cerebellum

    International Nuclear Information System (INIS)

    Somatotopic representation in the cerebral cortex of somatosensory stimulation has been widely reported, but that in the cerebellum has not. We investigated the latter in the human cerebellum by functional MRI (fMRI). Using a 1.5 tesla imager, we obtained multislice blood oxygen level-dependent fMRI with single-shot gradient-echo echoplanar imaging in seven right-handed volunteers during electrical stimulation of the left index finger and big toe. In the anterior and posterior cerebellum, activated pixels for the index finger were separate from those for the toe. This suggests that somatosensory stimulation of different parts of the body may involve distinct areas of in the cerebellum as well as the cerebral cortex. (orig.)

  3. Optimal T2* weighting for BOLD-type functional MRI of the human brain

    International Nuclear Information System (INIS)

    Optimal T2* weighting in blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (MRI) depends on the local field homogeneity. In areas with relatively poor shimming, the size of the BOLD effect decreases and the optimum echo time becomes smaller. T2* weighting can be accomplished with echo-planar imaging and conventional gradient-echo imaging. Neither method is optimal, since part of the data is either acquired with short echo times in case of EPI, or substantial time is lost due to delayed acquisition in case of long echo time FLASH. To improve efficiency, echo-shifted gradient echo imaging can be used. For 2-D BOLD, a T2* preparation period can be used as an alternative. (author). 12 refs., 5 figs

  4. Relating resting-state fMRI and EEG whole-brain connectomes across frequency bands

    OpenAIRE

    Deligianni, Fani; Centeno, Maria; Carmichael, David W.; Clayden, Jonathan D.

    2014-01-01

    Whole brain functional connectomes hold promise for understanding human brain activity across a range of cognitive, developmental and pathological states. So called resting-state (rs) functional MRI studies have contributed to the brain being considered at a macroscopic scale as a set of interacting regions. Interactions are defined as correlation-based signal measurements driven by blood oxygenation level dependent (BOLD) contrast. Understanding the neurophysiological basis of these measurem...

  5. Relating resting-state fMRI and EEG whole-brain connectomes across frequency bands

    OpenAIRE

    FaniDeligianni

    2014-01-01

    Whole brain functional connectomes hold promise for understanding human brain activity across a range of cognitive, developmental and pathological states. So called ‘resting-state’ (rs) functional MRI studies have contributed to the brain being considered at a macroscopic scale as a set of interacting regions. Interactions are defined as correlation-based signal measurements driven by blood oxygenation level dependent (BOLD) contrast. Understanding the neurophysiological basis of these measur...

  6. Resting-State Functional Connectivity in Individuals with Down Syndrome and Williams Syndrome Compared with Typically Developing Controls.

    Science.gov (United States)

    Vega, Jennifer N; Hohman, Timothy J; Pryweller, Jennifer R; Dykens, Elisabeth M; Thornton-Wells, Tricia A

    2015-10-01

    The emergence of resting-state functional connectivity (rsFC) analysis, which examines temporal correlations of low-frequency (<0.1 Hz) blood oxygen level-dependent signal fluctuations between brain regions, has dramatically improved our understanding of the functional architecture of the typically developing (TD) human brain. This study examined rsFC in Down syndrome (DS) compared with another neurodevelopmental disorder, Williams syndrome (WS), and TD. Ten subjects with DS, 18 subjects with WS, and 40 subjects with TD each participated in a 3-Tesla MRI scan. We tested for group differences (DS vs. TD, DS vs. WS, and WS vs. TD) in between- and within-network rsFC connectivity for seven functional networks. For the DS group, we also examined associations between rsFC and other cognitive and genetic risk factors. In DS compared with TD, we observed higher levels of between-network connectivity in 6 out 21 network pairs but no differences in within-network connectivity. Participants with WS showed lower levels of within-network connectivity and no significant differences in between-network connectivity relative to DS. Finally, our comparison between WS and TD controls revealed lower within-network connectivity in multiple networks and higher between-network connectivity in one network pair relative to TD controls. While preliminary due to modest sample sizes, our findings suggest a global difference in between-network connectivity in individuals with neurodevelopmental disorders compared with controls and that such a difference is exacerbated across many brain regions in DS. However, this alteration in DS does not appear to extend to within-network connections, and therefore, the altered between-network connectivity must be interpreted within the framework of an intact intra-network pattern of activity. In contrast, WS shows markedly lower levels of within-network connectivity in the default mode network and somatomotor network relative to controls. These findings

  7. Comparison between end-tidal CO2 and respiration volume per time for detecting BOLD signal fluctuations during paced hyperventilation

    OpenAIRE

    Vogt, Keith M.; Ibinson, James W; Schmalbrock, Petra; Small, Robert H

    2011-01-01

    Respiratory motion and capnometry monitoring were performed during blood oxygen level dependent (BOLD) functional magnetic resonance imaging (FMRI) of the brain while a series of paced hyperventilation tasks were performed that caused significant hypocapnia. Respiration volume per time (RVT) and end-tidal carbon dioxide (ETCO2) were determined and compared for their ability to explain BOLD contrast changes in the data. A 35% decrease in ETCO2 was observed along with corresponding changes in R...

  8. Functional magnetic resonance imaging.

    Science.gov (United States)

    Buchbinder, Bradley R

    2016-01-01

    Functional magnetic resonance imaging (fMRI) maps the spatiotemporal distribution of neural activity in the brain under varying cognitive conditions. Since its inception in 1991, blood oxygen level-dependent (BOLD) fMRI has rapidly become a vital methodology in basic and applied neuroscience research. In the clinical realm, it has become an established tool for presurgical functional brain mapping. This chapter has three principal aims. First, we review key physiologic, biophysical, and methodologic principles that underlie BOLD fMRI, regardless of its particular area of application. These principles inform a nuanced interpretation of the BOLD fMRI signal, along with its neurophysiologic significance and pitfalls. Second, we illustrate the clinical application of task-based fMRI to presurgical motor, language, and memory mapping in patients with lesions near eloquent brain areas. Integration of BOLD fMRI and diffusion tensor white-matter tractography provides a road map for presurgical planning and intraoperative navigation that helps to maximize the extent of lesion resection while minimizing the risk of postoperative neurologic deficits. Finally, we highlight several basic principles of resting-state fMRI and its emerging translational clinical applications. Resting-state fMRI represents an important paradigm shift, focusing attention on functional connectivity within intrinsic cognitive networks. PMID:27432660

  9. Aberrant function of learning and cognitive control networks underlie inefficient cognitive flexibility in anorexia nervosa: a cross-sectional fMRI study.

    Directory of Open Access Journals (Sweden)

    Nick P Lao-Kaim

    Full Text Available People with Anorexia Nervosa exhibit difficulties flexibly adjusting behaviour in response to environmental changes. This has previously been attributed to problematic behavioural shifting, characterised by a decrease in fronto-striatal activity. Additionally, alterations of instrumental learning, which relies on fronto-striatal networks, may contribute to the observation of inflexible behaviour. The authors sought to investigate the neural correlates of cognitive flexibility and learning in Anorexia Nervosa.Thirty-two adult females with Anorexia Nervosa and thirty-two age-matched female control participants completed the Wisconsin Card Sorting Task whilst undergoing functional magnetic resonance imaging. Event-related analysis permitted the comparison of cognitive shift trials against those requiring maintenance of rule-sets and allowed assessment of trials representing learning.Although both groups performed similarly, we found significant interactions in the left middle frontal gyrus, precuneus and superior parietal lobule whereby blood-oxygenated-level dependent response was higher in Anorexia Nervosa patients during shifting but lower when maintaining rule-sets, as compared to healthy controls. During learning, posterior cingulate cortex activity in healthy controls decreased whilst increasing in the Anorexia Nervosa group, whereas the right precuneus exhibited the opposite pattern. Furthermore, learning was associated with lower blood-oxygenated-level dependent response in the caudate body, as compared to healthy controls.People with Anorexia Nervosa display widespread changes in executive function. Whilst cognitive flexibility appears to be associated with aberrant functioning of the fronto-parietal control network that mediates between internally and externally directed cognition, fronto-striatal alterations, particularly within the caudate body, were associated with instrumental learning. Together, this shows how perseverative

  10. Aberrant Function of Learning and Cognitive Control Networks Underlie Inefficient Cognitive Flexibility in Anorexia Nervosa: A Cross-Sectional fMRI Study

    Science.gov (United States)

    Lao-Kaim, Nick P.; Fonville, Leon; Giampietro, Vincent P.; Williams, Steven C. R.; Simmons, Andrew; Tchanturia, Kate

    2015-01-01

    Objectives People with Anorexia Nervosa exhibit difficulties flexibly adjusting behaviour in response to environmental changes. This has previously been attributed to problematic behavioural shifting, characterised by a decrease in fronto-striatal activity. Additionally, alterations of instrumental learning, which relies on fronto-striatal networks, may contribute to the observation of inflexible behaviour. The authors sought to investigate the neural correlates of cognitive flexibility and learning in Anorexia Nervosa. Method Thirty-two adult females with Anorexia Nervosa and thirty-two age-matched female control participants completed the Wisconsin Card Sorting Task whilst undergoing functional magnetic resonance imaging. Event-related analysis permitted the comparison of cognitive shift trials against those requiring maintenance of rule-sets and allowed assessment of trials representing learning. Results Although both groups performed similarly, we found significant interactions in the left middle frontal gyrus, precuneus and superior parietal lobule whereby blood-oxygenated-level dependent response was higher in Anorexia Nervosa patients during shifting but lower when maintaining rule-sets, as compared to healthy controls. During learning, posterior cingulate cortex activity in healthy controls decreased whilst increasing in the Anorexia Nervosa group, whereas the right precuneus exhibited the opposite pattern. Furthermore, learning was associated with lower blood-oxygenated-level dependent response in the caudate body, as compared to healthy controls. Conclusions People with Anorexia Nervosa display widespread changes in executive function. Whilst cognitive flexibility appears to be associated with aberrant functioning of the fronto-parietal control network that mediates between internally and externally directed cognition, fronto-striatal alterations, particularly within the caudate body, were associated with instrumental learning. Together, this shows how

  11. Effects of iodinated contrast media on renal function in patients with multiple myeloma

    International Nuclear Information System (INIS)

    Case histories of 89 patients with definite myoloma of the years 1959 to 1974 were investigated in a retrospective study. 41 intravenous urographies were carried out in 31 of these patients. There was no correlation between deterioration of the renal function and contrast medium application. Relevant literature on the subject has been compiled. By 1979, 19 case studies and 5 general studies had been published which have been summarized in tables in the present study. Analyses of these case histories have shown that acute renal failure was often due to other causes and not to contrast medium application. If these cases are left out of account 8 cases remain in which lethal renal failure occurred after intravenous urography of myeloma patients. The diiodinated contrast media formerly used was less well tolerated than the present triiodinated contrast media. Further risk factors were dehydratation and/or abdominal compression. Both measures are no longer employed in intravenous urography. (orig./MG)

  12. Synthesis of functionalized magnetite nanoparticles to use as liver targeting MRI contrast agent

    Science.gov (United States)

    Yazdani, Farshad; Fattahi, Bahare; Azizi, Najmodin

    2016-05-01

    The aim of this research was the preparation of functionalized magnetite nanoparticles to use as a liver targeting contrast agent in magnetic resonance imaging (MRI). For this purpose, Fe3O4 nanoparticles were synthesized via the co-precipitation method. The synthesized nanoparticles were coated with silica via the Stober method and finally the coated nanoparticles were functionalized with mebrofenin. Formation of crystalline magnetite particles was confirmed by X-ray diffraction (XRD) analysis. The Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray analyzer (EDX) of the final product showed that silica had been effectively bonded onto the surface of the magnetite nanoparticles and the coated nanoparticles functionalized with mebrofenin. The magnetic resonance imaging of the functional nanoparticles showed that the Fe3O4-SiO2-mebrofenin composite is an effective MRI contrast agent for liver targeting.

  13. LHRH-functionalized superparamagnetic iron oxide nanoparticles for breast cancer targeting and contrast enhancement in MRI

    International Nuclear Information System (INIS)

    This paper shows that superparamagnetic iron oxide nanoparticles (SPIONs) conjugated to luteinizing hormone releasing hormone (LHRH) (LHRH-SPIONs), can be used to target breast cancer cells. They also act as contrast enhancement agents during the magnetic resonance imaging of breast cancer xenografts. A combination of transmission electron microscopy (TEM) and spectrophotometric analysis was used in our experiments, to investigate the specific accumulation of the functionalized superparamagnetic iron oxide nanoparticles (SPIONs) in cancer cells. The contrast enhancement of conventional T2 images obtained from the tumor tissue and of breast cancer xenograft bearing mice is shown to be much greater than that in saline controls, when the tissues were injected with LHRH-SPIONs. Magnetic anisotropy multi-CRAZED images of tissues extracted from mice injected with SPIONs were also found to have enhanced MRI contrast in breast cancer xenografts and metastases in the lungs.

  14. LHRH-functionalized superparamagnetic iron oxide nanoparticles for breast cancer targeting and contrast enhancement in MRI

    Energy Technology Data Exchange (ETDEWEB)

    Meng, J.; Fan, J. [Princeton Institute of Science and Technology of Materials and the Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Galiana, G. [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Branca, R.T. [Department of Chemistry, Duke University, Durham, NC 27708-0354 (United States); Clasen, P.L.; Ma, S. [Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, PA 18015-3195 (United States); Zhou, J. [Princeton Institute of Science and Technology of Materials and the Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Leuschner, C. [Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808 (United States); Kumar, C.S.S.R.; Hormes, J. [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Hwy, Baton Rouge, LA 70806 (United States); Otiti, T. [Department of Physics, Makerere University, Kampala (Uganda); Beye, A.C. [Department of Physics, Cheikh Anta Diop University, Dakar (Senegal); Harmer, M.P.; Kiely, C.J. [Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, PA 18015-3195 (United States); Warren, W. [Department of Chemistry, Duke University, Durham, NC 27708-0354 (United States); Haataja, M.P. [Princeton Institute of Science and Technology of Materials and the Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Soboyejo, W.O., E-mail: soboyejo@princeton.edu [Princeton Institute of Science and Technology of Materials and the Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2009-05-05

    This paper shows that superparamagnetic iron oxide nanoparticles (SPIONs) conjugated to luteinizing hormone releasing hormone (LHRH) (LHRH-SPIONs), can be used to target breast cancer cells. They also act as contrast enhancement agents during the magnetic resonance imaging of breast cancer xenografts. A combination of transmission electron microscopy (TEM) and spectrophotometric analysis was used in our experiments, to investigate the specific accumulation of the functionalized superparamagnetic iron oxide nanoparticles (SPIONs) in cancer cells. The contrast enhancement of conventional T2 images obtained from the tumor tissue and of breast cancer xenograft bearing mice is shown to be much greater than that in saline controls, when the tissues were injected with LHRH-SPIONs. Magnetic anisotropy multi-CRAZED images of tissues extracted from mice injected with SPIONs were also found to have enhanced MRI contrast in breast cancer xenografts and metastases in the lungs.

  15. Semiparametric Methods to Contrast Gap Time Survival Functions: Application to Repeat Kidney Transplantation

    OpenAIRE

    Shu, Xu; Schaubel, Douglas E.

    2015-01-01

    Times between successive events (i.e., gap times) are of great importance in survival analysis. Although many methods exist for estimating covariate effects on gap times, very few existing methods allow for comparisons between gap times themselves. Motivated by the comparison of primary and repeat transplantation, our interest is specifically in contrasting the gap time survival functions and their integration (restricted mean gap time). Two major challenges in gap time analysis are non-ident...

  16. The value of blood oxygenation level-dependent (BOLD MR imaging in differentiation of renal solid mass and grading of renal cell carcinoma (RCC: analysis based on the largest cross-sectional area versus the entire whole tumour.

    Directory of Open Access Journals (Sweden)

    Guang-Yu Wu

    Full Text Available To study the value of assessing renal masses using different methods in parameter approaches and to determine whether BOLD MRI is helpful in differentiating RCC from benign renal masses, differentiating clear-cell RCC from renal masses other than clear-cell RCC and determining the tumour grade.Ninety-five patients with 139 renal masses (93 malignant and 46 benign who underwent abdominal BOLD MRI were enrolled. R2* values were derived from the largest cross-section (R2*largest and from the whole tumour (R2*whole. Intra-observer and inter-observer agreements were analysed based on two measurements by the same observer and the first measurement from each observer, respectively, and these agreements are reported with intra-class correlation coefficients and 95% confidence intervals. The diagnostic value of the R2* value in the evaluation was assessed with receiver-operating characteristic analysis.The intra-observer agreement was very good for R2*largest and R2*whole (all > 0.8. The inter-observer agreement of R2*whole (0.75, 95% confidence interval: 0.69~0.79 was good and was significantly improved compared with the R2*largest (0.61, 95% confidence interval: 0.52~0.68, as there was no overlap in the 95% confidence interval of the intra-class correlation coefficients. The diagnostic value in differentiating renal cell carcinoma from benign lesions with R2*whole (AUC=0.79/0.78[observer1/observer2] and R2*largest (AUC=0.75[observer1] was good and significantly higher (p=0.01 for R2*largest[observer2] vs R2*whole[observer2], p 0.7 and were not significantly different (p=0.89/0.93 for R2*largest vs R2*whole[observer1/observer2], 0.96 for R2*whole[observer1] vs R2*largest[observer2] and 0.96 for R2*whole [observer2] vs R2*largest[observer1].BOLD MRI could provide a feasible parameter for differentiating renal cell carcinoma from benign renal masses and for predicting clear-cell renal cell carcinoma grading. Compared with the largest cross-section, assessing the whole tumour provides better inter-observer agreement in parameter measurement for differentiating renal cell carcinoma from benign renal masses.

  17. Contrast-enhanced optical coherence tomography with picomolar sensitivity for functional in vivo imaging

    Science.gov (United States)

    Liba, Orly; Sorelle, Elliott D.; Sen, Debasish; de La Zerda, Adam

    2016-03-01

    Optical Coherence Tomography (OCT) enables real-time imaging of living tissues at cell-scale resolution over millimeters in three dimensions. Despite these advantages, functional biological studies with OCT have been limited by a lack of exogenous contrast agents that can be distinguished from tissue. Here we report an approach to functional OCT imaging that implements custom algorithms to spectrally identify unique contrast agents: large gold nanorods (LGNRs). LGNRs exhibit 110-fold greater spectral signal per particle than conventional GNRs, which enables detection of individual LGNRs in water and concentrations as low as 250 pM in the circulation of living mice. This translates to ~40 particles per imaging voxel in vivo. Unlike previous implementations of OCT spectral detection, the methods described herein adaptively compensate for depth and processing artifacts on a per sample basis. Collectively, these methods enable high-quality noninvasive contrast-enhanced imaging of OCT in living subjects, including detection of tumor microvasculature at twice the depth achievable with conventional OCT. Additionally, multiplexed detection of spectrally-distinct LGNRs was demonstrated to observe discrete patterns of lymphatic drainage and identify individual lymphangions and lymphatic valve functional states. These capabilities provide a powerful platform for molecular imaging and characterization of tissue noninvasively at cellular resolution, called MOZART.

  18. Using contrast transfer function to evaluate the effect of motion blur on microscope image quality

    Science.gov (United States)

    Wood, Marc C.; Wang, Xingwei; Zheng, Bin; Li, Shibo; Chen, Wei; Liu, Hong

    2008-02-01

    Scanning of microscope slides is an important part of cytogenetic diagnosis. Metaphase chromosomes arranged in a karyotype reveal the nature and severity of cancer and other diseases. Searching for metaphases spreads is a lengthy and tedious process that can benefit from computer aided systems. When slides are searched by such systems in continuous motion, the image quality is reduced. The motion blur is a function of the scan speed, the camera frame rate and sample time, and the level of magnification. In this study, normalized contrast transfer function (CTF) is used to define the amount of image degradation.

  19. A novel functional CT contrast agent for molecular imaging of cancer

    Science.gov (United States)

    Li, Ji; Chaudhary, Ahmed; Chmura, Steven J.; Pelizzari, Charles; Rajh, Tijana; Wietholt, Christian; Kurtoglu, Metin; Aydogan, Bulent

    2010-08-01

    The purpose of this study was to investigate the feasibility of using a 2-deoxy-d-glucose (2-DG) labeled gold nanoparticle (AuNP-2-DG) as a functionally targeted computed tomography (CT) contrast agent to obtain high-resolution metabolic and anatomic information of tumor in a single CT scan. Gold nanoparticles (AuNPs) were fabricated and were conjugated with 1-DG or 2-DG. 1-DG provides an excellent comparison since it is known to interfere with the ability of the glucose transporter to recognize the sugar moiety. The human alveolar epithelial cancer cell line, A-549, was chosen for the in vitro cellular uptake assay. Three groups of cell samples were incubated with the 1-DG or 2-DG labeled AuNP and the unlabeled AuNP. Following the incubation, the cells were washed with sterile phosphate buffered saline to remove the excess AuNPs and spun using a centrifuge. The cell pellets were imaged using a microCT scanner immediately after the centrifugation. Internalization of AuNP-2-DG is verified using transmission electron microscopy imaging. Significant contrast enhancement in the cell samples incubated with the AuNP-2-DG with respect to the cell samples incubated with the unlabeled AuNP and the AuNP-1-DG was observed in multiple CT slices. Results from our in vitro experiments suggest that the AuNP-2-DG may be used as a functional CT contrast agent to provide high-resolution metabolic and anatomic information in a single CT scan. These results justify further in vitro and in vivo experiments to study the feasibility of using the AuNP-2-DG as a functional CT contrast agent in radiation therapy settings.

  20. A novel functional CT contrast agent for molecular imaging of cancer

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the feasibility of using a 2-deoxy-d-glucose (2-DG) labeled gold nanoparticle (AuNP-2-DG) as a functionally targeted computed tomography (CT) contrast agent to obtain high-resolution metabolic and anatomic information of tumor in a single CT scan. Gold nanoparticles (AuNPs) were fabricated and were conjugated with 1-DG or 2-DG. 1-DG provides an excellent comparison since it is known to interfere with the ability of the glucose transporter to recognize the sugar moiety. The human alveolar epithelial cancer cell line, A-549, was chosen for the in vitro cellular uptake assay. Three groups of cell samples were incubated with the 1-DG or 2-DG labeled AuNP and the unlabeled AuNP. Following the incubation, the cells were washed with sterile phosphate buffered saline to remove the excess AuNPs and spun using a centrifuge. The cell pellets were imaged using a microCT scanner immediately after the centrifugation. Internalization of AuNP-2-DG is verified using transmission electron microscopy imaging. Significant contrast enhancement in the cell samples incubated with the AuNP-2-DG with respect to the cell samples incubated with the unlabeled AuNP and the AuNP-1-DG was observed in multiple CT slices. Results from our in vitro experiments suggest that the AuNP-2-DG may be used as a functional CT contrast agent to provide high-resolution metabolic and anatomic information in a single CT scan. These results justify further in vitro and in vivo experiments to study the feasibility of using the AuNP-2-DG as a functional CT contrast agent in radiation therapy settings.

  1. Comparison of renal toxicity after injection of CT contrast medium and MR contrast medium: change of renal function in acute renal failure rat models

    International Nuclear Information System (INIS)

    To determine renal toxicity through changes in renal function after the injection of CT and MRI contrast media into rats in which acute renal failure (ARF) was induced. To cause acute renal failure, the abdominal cavity of 110 male rats each weighing 250-300 gm was opened via a midline incision under anesthesia. Microvascular clamps were placed on both renal arteries and veins to completely block renal blood flow for 45 minutes, and were then removed, allowing blood flow to return to the kidneys. ARF, defined as a two-fold difference in the creatinine level before ARF and 48 hours after, was successfully induced in 60 of the rats. These were divided into two groups: one was injected with CT contrast medium and the other with MRI contrast medium. Each CT and MRI group was divided into a low dose (0.5 cc/kg, 0.2 ml/kg), standard dose (2 cc/kg, 0.8 ml/kg), and high dose (8 cc/kg, 3.2 ml/kg) sub-group; thus, there was a total of six groups with ten rats in each. Blood samples were obtained before ARF, 48 hours after, and 48 hours after contrast injection, and CT scanning and MRI were performed after blood sampling at 48 hours. In each group, creatinine levels 48 hours after contrast injection were compared by means of the ANOVA test. There were no significant differences in creatinine levels between the CT and MRI contrast medium groups (p=0.116), nor between the animals to which different doses of CT and MRI contrast medium, were administered. After both standard and high doses, CT and MRI provided good images. In rats in which acute renal failure was induced, renal function did not change according to whether CT or MRI contrast medium was injected. Thus, the two media induce similar levels of toxicity

  2. Towards an Analytical Age-Dependent Model of Contrast Sensitivity Functions for an Ageing Society

    Science.gov (United States)

    Joulan, Karine; Brémond, Roland

    2015-01-01

    The Contrast Sensitivity Function (CSF) describes how the visibility of a grating depends on the stimulus spatial frequency. Many published CSF data have demonstrated that contrast sensitivity declines with age. However, an age-dependent analytical model of the CSF is not available to date. In this paper, we propose such an analytical CSF model based on visual mechanisms, taking into account the age factor. To this end, we have extended an existing model from Barten (1999), taking into account the dependencies of this model's optical and physiological parameters on age. Age-dependent models of the cones and ganglion cells densities, the optical and neural MTF, and optical and neural noise are proposed, based on published data. The proposed age-dependent CSF is finally tested against available experimental data, with fair results. Such an age-dependent model may be beneficial when designing real-time age-dependent image coding and display applications. PMID:26078994

  3. Investigating atomic contrast in atomic force microscopy and Kelvin probe force microscopy on ionic systems using functionalized tips

    OpenAIRE

    Gross, Leo; Schuler, Bruno; Mohn, Fabian; Moll, Nikolaj; Pavliček, Niko; Steurer, Wolfram; Scivetti, Ivan; Kotsis, Konstantinos; Persson, Mats; Meyer, Gerhard

    2014-01-01

    Noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM) have become important tools for nanotechnology; however, their contrast mechanisms on the atomic scale are not entirely understood. Here we used chlorine vacancies in NaCl bilayers on Cu(111) as a model system to investigate atomic contrast as a function of applied voltage, tip height, and tip functionalization. We demonstrate that the AFM contrast on the atomic scale decisively depends on both the tip termin...

  4. Multiscale finite element methods for high-contrast problems using local spectral basis functions

    KAUST Repository

    Efendiev, Yalchin

    2011-02-01

    In this paper we study multiscale finite element methods (MsFEMs) using spectral multiscale basis functions that are designed for high-contrast problems. Multiscale basis functions are constructed using eigenvectors of a carefully selected local spectral problem. This local spectral problem strongly depends on the choice of initial partition of unity functions. The resulting space enriches the initial multiscale space using eigenvectors of local spectral problem. The eigenvectors corresponding to small, asymptotically vanishing, eigenvalues detect important features of the solutions that are not captured by initial multiscale basis functions. Multiscale basis functions are constructed such that they span these eigenfunctions that correspond to small, asymptotically vanishing, eigenvalues. We present a convergence study that shows that the convergence rate (in energy norm) is proportional to (H/Λ*)1/2, where Λ* is proportional to the minimum of the eigenvalues that the corresponding eigenvectors are not included in the coarse space. Thus, we would like to reach to a larger eigenvalue with a smaller coarse space. This is accomplished with a careful choice of initial multiscale basis functions and the setup of the eigenvalue problems. Numerical results are presented to back-up our theoretical results and to show higher accuracy of MsFEMs with spectral multiscale basis functions. We also present a hierarchical construction of the eigenvectors that provides CPU savings. © 2010.

  5. Effect on renal function of an iso-osmolar contrast agent in patients with monoclonal gammopathies

    Energy Technology Data Exchange (ETDEWEB)

    Preda, Lorenzo [Division of Radiology, European Institute of Oncology, IRCCS, Milan (Italy); Agazzi, Alberto; Martinelli, Giovanni [Division of Haematology, European Institute of Oncology, IRCCS, Milan (Italy); Raimondi, Sara [Division of Epidemiology and Biostatistics, European Institute of Oncology, IRCCS, Milan (Italy); University of Milan, Department of Occupational Medicin ' ' Clinica del Lavoro Luigi Devoto' ' Section of Medical Statistics and Biometry ' ' GA Maccacaro' ' , Milan (Italy); Lanfranchi, Carla Federica [University of Milan, IRCCS, School of Medicine, Milan (Italy); Passerini, Rita [Unit of Laboratory Medicine, European Institute of Oncology, IRCCS, Milan (Italy); Calvetta, Albania [Nephrology and Dialysis Unit, Istituto Clinico Humanitas, IRCCS, Rozzano, Milan (Italy); Bellomi, Massimo [Division of Radiology, European Institute of Oncology, IRCCS, Milan (Italy); University of Milan, IRCCS, School of Medicine, Milan (Italy)

    2011-01-15

    To assess the safety of the non-ionic iso-osmolar contrast agent iodixanol on renal function in patients with monoclonal gammopathies undergoing CT. We explored the effect of iodixanol on renal function in 30 patients with monoclonal gammopathies and 20 oncological patients with a normal electrophoretic profile (control group). The parameters used to estimate renal function were: serum creatinine, eGFR (determined 24 h before and 48 h after the administration of iodixanol), and urinary excretion of Neutrophil Gelatinase-Associated Lipocalin (NGAL) determined 2 h and 24 h after. Serum creatinine was also determined 1 month after the administration of iodixanol. No significant increase in serum creatinine values were observed in the monoclonal gammopathies group and in 19/20 patients in the control group. Only 1 patient in the control group developed a transient contrast agent-induced nephropathy. We found no statistically significant difference between the two groups regarding the percentage variation from baseline values of serum creatinine, creatinine clearance, NGAL 2 h after, and eGFR. Whereas NGAL at 24 h showed a statistically significant increase in patients with Monoclonal gammopathies. The use of iodixanol appears to be safe in patients with monoclonal gammopathies and an eGFR {>=} 60 ml/min/1.73 mq. (orig.)

  6. The influence of contrast media on kidney function in patients with stable coronary artery disease

    DEFF Research Database (Denmark)

    Reuter, Simon Bertram; Harutyunyan, Marina; Mygind, Naja Dam;

    2014-01-01

    AIMS: To investigate the incidence of contrast media-induced nephropathy (CIN) in patients with stable coronary artery disease (CAD) referred for elective coronary intervention following hydration routines. The reversibility of CIN was followed in a 6 month-period. METHODS AND RESULTS: A total....... Kidney function was not normalized in CIN patients 6 months after the intervention. Two patients still met the definition of CIN. CONCLUSION: With no restriction in fluid intake and supplementary infusion of saline, only a few patients with stable CAD developed early indications of CIN during elective...

  7. Contrast Sensitivity Function of Sound Eye after Occlusion Therapy in the Amblyopic Children

    OpenAIRE

    Lew, Helen; Han, Sueng-Han; Jong-Bok LEE; Lee, Eun-Seok

    2005-01-01

    To verify the changes of mesopic and photopic contrast sensitivity function of sound eye whose visual acuity was kept the same after occlusion therapy in the amblyopic children. Fourteen sound eyes of amblyopic children (mean; 7.67 years; S.D., 1.50 years) who kept their visual acuity the same after the occlusion therapy were tested. The children had 6 hours of part-time patch therapy for 3 months prior to this examination. Among 14 amblyopic children, 8 were anisometric and 6 were strabismic...

  8. Average arterial input function for quantitative dynamic contrast enhanced magnetic resonance imaging of neck nodal metastases

    OpenAIRE

    Shukla-Dave, Amita; Lee, Nancy; Stambuk, Hilda; Wang, YA; Huang, Wei; Howard T Thaler; Patel, Snehal G.; Shah, Jatin P.; Koutcher, Jason A

    2009-01-01

    Background The present study determines the feasibility of generating an average arterial input function (Avg-AIF) from a limited population of patients with neck nodal metastases to be used for pharmacokinetic modeling of dynamic contrast-enhanced MRI (DCE-MRI) data in clinical trials of larger populations. Methods Twenty patients (mean age 50 years [range 27–77 years]) with neck nodal metastases underwent pretreatment DCE-MRI studies with a temporal resolution of 3.75 to 7.5 sec on a 1.5T c...

  9. Theory of x-ray holography including phase and amplitude contrast and finite transfer functions

    International Nuclear Information System (INIS)

    We present the theory in broadly the same way as for visible holography, specializing to the Gabor, in-line case with plane-wave illumination, but allowing phase and amplitude contrast and a fairly general transfer function. Much of this theory is treated by a number of earlier authors but none with the particular choice of issues that we wish to address. These are those mentioned plus numerical reconstruction from a digitized hologram and of course application to the soft x-ray spectral range. For simplicity and clarity, we consider first an amplitude and phase object consisting of a single, on-axis pixel and an ideal, perfect transfer function. (12 refs., 4 figs.)

  10. Semiparametric methods to contrast gap time survival functions: Application to repeat kidney transplantation.

    Science.gov (United States)

    Shu, Xu; Schaubel, Douglas E

    2016-06-01

    Times between successive events (i.e., gap times) are of great importance in survival analysis. Although many methods exist for estimating covariate effects on gap times, very few existing methods allow for comparisons between gap times themselves. Motivated by the comparison of primary and repeat transplantation, our interest is specifically in contrasting the gap time survival functions and their integration (restricted mean gap time). Two major challenges in gap time analysis are non-identifiability of the marginal distributions and the existence of dependent censoring (for all but the first gap time). We use Cox regression to estimate the (conditional) survival distributions of each gap time (given the previous gap times). Combining fitted survival functions based on those models, along with multiple imputation applied to censored gap times, we then contrast the first and second gap times with respect to average survival and restricted mean lifetime. Large-sample properties are derived, with simulation studies carried out to evaluate finite-sample performance. We apply the proposed methods to kidney transplant data obtained from a national organ transplant registry. Mean 10-year graft survival of the primary transplant is significantly greater than that of the repeat transplant, by 3.9 months (p=0.023), a result that may lack clinical importance. PMID:26501480

  11. Arterial input function calculation in dynamic contrast-enhanced MRI: an in vivo validation study using co-registered contrast-enhanced ultrasound imaging

    International Nuclear Information System (INIS)

    Developing a method of separating intravascular contrast agent concentration to measure the arterial input function (AIF) in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of tumours, and validating its performance in phantom and in vivo experiments. A tissue-mimicking phantom was constructed to model leaky tumour vasculature and DCE-MR images of this phantom were acquired. An in vivo study was performed using tumour-bearing rabbits. Co-registered DCE-MRI and contrast-enhanced ultrasound (CEUS) images were acquired. An independent component analysis (ICA)-based method was developed to separate the intravascular component from DCE-MRI. Results were validated by comparing the time-intensity curves with the actual phantom and in vivo curves. Phantom study: the AIF extracted using ICA correlated well with the true intravascular curve. In vivo study: the AIFs extracted from DCE-MRI using ICA were very close to the true AIF. Intravascular component images were very similar to the CEUS images. The contrast onset times and initial wash-in slope of the ICA-derived AIF showed good agreement with the CEUS curves. ICA has the potential to separate the intravascular component from DCE-MRI. This could eliminate the requirement for contrast medium uptake measurements in a major artery and potentially result in more accurate pharmacokinetic parameters. (orig.)

  12. Contrasting Evolutionary Patterns of Functional Connectivity in Sensorimotor and Cognitive Regions after Stroke

    Science.gov (United States)

    Liu, Huaigui; Tian, Tian; Qin, Wen; Li, Kuncheng; Yu, Chunshui

    2016-01-01

    The human brain is a highly connected and integrated system. Local stroke lesions can evoke reorganization in multiple functional networks. However, the temporally-evolving patterns in different functional networks after stroke remain unclear. Here, we aimed to investigate the dynamic evolutionary patterns of functional connectivity density (FCD) and strength (FCS) of the brain after subcortical stroke involving in the motor pathways. Eight male patients with left subcortical infarctions were longitudinally examined at five time points within a year. Voxel-wise FCD analysis was used to identify brain regions with significant dynamic changes. The temporally-evolving patterns in FCD and FCS in these regions were analyzed by a mixed-effects model. Associations between these measures and clinical variables were also explored in stroke patients. Voxel-wise analysis revealed dynamic FCD changes only in the sensorimotor and cognitive regions after stroke. FCD and FCS in the sensorimotor regions decreased initially, as compared to controls, remaining at lower levels for months, and finally returned to normal levels. In contrast, FCD and FCS in the cognitive regions increased initially, remaining at higher levels for months, and finally returned to normal levels. Most of these measures were correlated with patients’ motor scores. These findings suggest a network-specific dynamic functional reorganization after stroke. Besides the sensorimotor regions, the spared cognitive regions may also play an important role in stroke recovery. PMID:27147993

  13. Functional imaging of the lung using a gaseous contrast agent: 3Helium-magnetic resonance imaging

    International Nuclear Information System (INIS)

    Current imaging methods of the lung concentrate on morphology as well as on the depiction of the pulmonary parenchyma. The need of an advanced and more subtle imaging technology compared to conventional radiography is met by computed topograhy as the method of choice. Nevertheless, computed tomography yields very limited functional information. This is to be derived from arterial blood gas analysis, spirometry and body plethysmography. These methods, however, lack the scope for regional allocation of any pathology. Magnetic resonance imaging of the lung has been advanced by the use of hyperpolarised 3Helium as an inhaled gaseous contrast agent. The inhalation of the gas provides functional data by distribution, diffusion and relaxation of its hyperpolarised state. Because anatomical landmarks of the lung can be visualised as well, functional information can be linked with regional information. Furthermore, the method provides high spatial and temporal resolution and lacks the potential side-effects of ionising radiation. Four different modalities have been established: 1. Spin density imaging studies the distribution of gas, normally after a single inhalation of contrast gas in inspiratory breath hold. 2. Dynamic cine imaging studies the distribution of gas with respect to regional time constants of pulmonary gas inflow. 3. Diffusion weighted imaging can exhibit the presence and severity of pulmonary airspace enlargement, as in pulmonary emphysema. 4. Oxygen sensitive imaging displays intrapulmonary oxygen partial pressure and its distribution. Currently, the method is limited by comparably high costs and limited availability. As there have been recent developments which might bring this modality closer to clinical use, this review article will comprise the methodology as well as the current state of the art and standard of knowledge of magnetic resonance imaging of the lung using hyperpolarised 3Helium. (orig.)

  14. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Schramm, S.M. [Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2013-02-15

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C{sub 3}-corrected microscopes it is well established that a small negative value of C{sub 3}, offset by positive values of C{sub 5} and defocus C{sub 1} results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C{sub 1} and C{sub 3}. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed.

  15. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    International Nuclear Information System (INIS)

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C3-corrected microscopes it is well established that a small negative value of C3, offset by positive values of C5 and defocus C1 results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C1 and C3. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed

  16. Hyaluronic acid-functionalized single-walled carbon nanotubes as tumor-targeting MRI contrast agent

    Directory of Open Access Journals (Sweden)

    Hou L

    2015-07-01

    Full Text Available Lin Hou,* Huijuan Zhang,* Yating Wang, Lili Wang, Xiaomin Yang, Zhenzhong ZhangSchool of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, People’s Republic of China*These authors contributed equally to this workAbstract: A tumor-targeting carrier, hyaluronic acid (HA-functionalized single-walled carbon nanotubes (SWCNTs, was explored to deliver magnetic resonance imaging (MRI contrast agents (CAs targeting to the tumor cells specifically. In this system, HA surface modification for SWCNTs was simply accomplished by amidation process and could make this nanomaterial highly hydrophilic. Cellular uptake was performed to evaluate the intracellular transport capabilities of HA-SWCNTs for tumor cells and the uptake rank was HA-SWCNTs> SWCNTs owing to the presence of HA, which was also evidenced by flow cytometry. The safety evaluation of this MRI CAs was investigated in vitro and in vivo. It revealed that HA-SWCNTs could stand as a biocompatible nanocarrier and gadolinium (Gd/HA-SWCNTs demonstrated almost no toxicity compared with free GdCl3. Moreover, GdCl3 bearing HA-SWCNTs could significantly increase the circulation time for MRI. Finally, to investigate the MRI contrast enhancing capabilities of Gd/HA-SWCNTs, T1-weighted MR images of tumor-bearing mice were acquired. The results suggested Gd/HA-SWCNTs had the highest tumor-targeting efficiency and T1-relaxivity enhancement, indicating HA-SWCNTs could be developed as a tumor-targeting carrier to deliver the CAs, GdCl3, for the identifiable diagnosis of tumor.Keywords: gadolinium, magnetic resonance, SWCNTs, hyaluronic acid, contrast agent

  17. Brain activation studies with PET and functional MRI

    International Nuclear Information System (INIS)

    Application of PET and functional MRI in brain activation studies is reviewed. 3D-PET images obtained repeatedly after intravenous injection of about 370 MBq of H215O can detect a faint blood flow change in the brain. Functional MRI can also detect the blood flow change in the brain due to blood oxygen level-dependent effect. Echo-planar imaging is popular in MRI with 1.5 or 3 T. Images are analyzed by statistical parametric mapping with correction of cerebral regions, anatomical normalization and statistics. PET data give the blood flow change by the H215O incorporation into the brain and MRI data, by the scarce tissue oxygen consumption despite the change. Actual images during the cognition task-performance and of frequent artifacts are given. PET is suitable for studies of brain functions like sensibility and emotion and functional MRI, like cortex functions and clinical practices in identification of functional regions prior to surgery and evaluation of functional recovery of damaged brain. (K.H.)

  18. Functional imaging using the retinal function imager: direct imaging of blood velocity, achieving fluorescein angiography-like images without any contrast agent, qualitative oximetry, and functional metabolic signals.

    Science.gov (United States)

    Izhaky, David; Nelson, Darin A; Burgansky-Eliash, Zvia; Grinvald, Amiram

    2009-07-01

    The Retinal Function Imager (RFI; Optical Imaging, Rehovot, Israel) is a unique, noninvasive multiparameter functional imaging instrument that directly measures hemodynamic parameters such as retinal blood-flow velocity, oximetric state, and metabolic responses to photic activation. In addition, it allows capillary perfusion mapping without any contrast agent. These parameters of retinal function are degraded by retinal abnormalities. This review delineates the development of these parameters and demonstrates their clinical applicability for noninvasive detection of retinal function in several modalities. The results suggest multiple clinical applications for early diagnosis of retinal diseases and possible critical guidance of their treatment. PMID:19763751

  19. Facile Synthesis of Gd-Functionalized Gold Nanoclusters as Potential MRI/CT Contrast Agents

    Directory of Open Access Journals (Sweden)

    Wenjun Le

    2016-04-01

    Full Text Available Multi-modal imaging plays a key role in the earlier detection of disease. In this work, a facile bioinspired method was developed to synthesize Gd-functionalized gold nanoclusters (Gd-Au NCs. The Gd-Au NCs exhibit a uniform size, with an average size of 5.6 nm in dynamic light scattering (DLS, which is a bit bigger than gold clusters (3.74 nm, DLS, while the fluorescent properties of Gd-Au NCs are almost the same as that of Au NCs. Moreover, the Gd-Au NCs exhibit a high longitudinal relaxivity value (r1 of 22.111 s−1 per mM of Gd in phosphate-buffered saline (PBS, which is six times higher than that of commercial Magnevist (A complex of gadolinium with a chelating agent, diethylenetriamine penta-acetic acid, Gd-DTPA, r1 = 3.56 mM−1·s−1. Besides, as evaluated by nano single photon emission computed tomography (SPECT and computed tomography (CT the Gd-Au NCs have a potential application as CT contrast agents because of the Au element. Finally, the Gd-Au NCs show little cytotoxicity, even when the Au concentration is up to 250 μM. Thus, the Gd-Au NCs can act as multi-modal imaging contrast agents.

  20. Quantitative functional lung imaging with synchrotron radiation using inhaled xenon as contrast agent

    Energy Technology Data Exchange (ETDEWEB)

    Bayat, S. [TIMC-PRETA, UMR CNRS 5525, Laboratoire de Physiologie, Universite Joseph Fourier, Faculte de Medecine, Domaine de la Merci, Grenoble (France)]. E-mail: sam.bayat@imag.fr; Le Duc, G.; Berruyer, G.; Nemoz, C.; Monfraix, S.; Fiedler, S.; Thomlinson, W. [European Synchrotron Radiation Facility, BP 220, Grenoble (France); Porra, L.; Suortti, P. [Department of Physics, University of Helsinki, Helsinki (Finland); Standertskjoeld-Nordenstam, C.G. [Department of Radiology, University of Helsinki Central Hospital, Helsinki (Finland); Sovijaervi, A.R.A. [Department of Clinical Physiology and Nuclear Medicine, Helsinki University Central Hospital, Helsinki (Finland)

    2001-12-01

    Small airways play a key role in the distribution of ventilation and in the matching of ventilation to perfusion. The purpose of this study was to introduce an imaging method that allows measurement of regional lung ventilation and evaluation of the function of airways with a small diameter. The experiments were performed at the Medical Beamline of the European Synchrotron Radiation Facility. Monochromatic synchrotron radiation beams were used to obtain quantitative respiration-gated images of lungs and airways in two anaesthetized and mechanically ventilated rabbits using inhaled stable xenon (Xe) gas as a contrast agent. Two simultaneous images were acquired at two different energies, above and below the K-edge of Xe. Logarithmic subtraction of the two images yields absolute Xe concentrations. This technique is known as K-edge subtraction (KES) radiography. Two-dimensional planar and CT images were obtained showing spatial distribution of Xe concentrations within the airspaces, as well as the dynamics of filling with Xe. Bronchi down to 1 mm in diameter were visible both in the subtraction radiographs and in tomographic images. Absolute concentrations of Xe gas were calculated within the tube carrying the inhaled gas mixture, small and large bronchi, and lung tissue. Local time constants of ventilation with Xe were obtained by following the evolution of gas concentration in sequential computed tomography images. The results of this first animal study indicate that KES imaging of lungs with Xe gas as a contrast agent has great potential in studies of the distribution of ventilation within the lungs and of airway function, including airways with a small diameter. (author)

  1. Concept of contrast transfer function for edge illumination x-ray phase-contrast imaging and its comparison with the free-space propagation technique.

    Science.gov (United States)

    Diemoz, Paul C; Vittoria, Fabio A; Olivo, Alessandro

    2016-05-16

    Previous studies on edge illumination (EI) X-ray phase-contrast imaging (XPCi) have investigated the nature and amplitude of the signal provided by this technique. However, the response of the imaging system to different object spatial frequencies was never explicitly considered and studied. This is required in order to predict the performance of a given EI setup for different classes of objects. To this scope, in the present work we derive analytical expressions for the contrast transfer function of an EI imaging system, using the approximation of near-field regime, and study its dependence upon the main experimental parameters. We then exploit these results to compare the frequency response of an EI system with respect of that of a free-space propagation XPCi one. The results achieved in this work can be useful for predicting the signals obtainable for different types of objects and also as a basis for new retrieval methods. PMID:27409946

  2. NEUROFEEDBACK USING FUNCTIONAL SPECTROSCOPY.

    Science.gov (United States)

    Hinds, Oliver; Wighton, Paul; Tisdall, M Dylan; Hess, Aaron; Breiter, Hans; van der Kouwe, André

    2014-06-01

    Neurofeedback based on real-time measurement of the blood oxygenation level-dependent (BOLD) signal has potential for treatment of neurological disorders and behavioral enhancement. Commonly employed methods are based on functional magnetic resonance imaging (fMRI) sequences that sacrifice speed and accuracy for whole-brain coverage, which is unnecessary in most applications. We present multi-voxel functional spectroscopy (MVFS): a system for computing the BOLD signal from multiple volumes of interest (VOI) in real-time that improves speed and accuracy of neurofeedback. MVFS consists of a functional spectroscopy (FS) pulse sequence, a BOLD reconstruction component, a neural activation estimator, and a stimulus system. The FS pulse sequence is a single-voxel, magnetic resonance spectroscopy sequence without water suppression that has been extended to allow acquisition of a different VOI at each repetition and real-time subject head motion compensation. The BOLD reconstruction component determines the T2* decay rate, which is directly related to BOLD signal strength. The neural activation estimator discounts nuisance signals and scales the activation relative to the amount of ROI noise. Finally, the neurofeedback system presents neural activation-dependent stimuli to experimental subjects with an overall delay of less than 1s. Here we present the MVFS system, validation of certain components, examples of its usage in a practical application, and a direct comparison of FS and echo-planar imaging BOLD measurements. We conclude that in the context of realtime BOLD imaging, MVFS can provide superior accuracy and temporal resolution compared with standard fMRI methods. PMID:24999293

  3. Compensatory recombination phenomena of neurological functions in central dysphagia patients

    Directory of Open Access Journals (Sweden)

    Xiao-dong Yuan

    2015-01-01

    Full Text Available We speculate that cortical reactions evoked by swallowing activity may be abnormal in patients with central infarction with dysphagia. The present study aimed to detect functional imaging features of cerebral cortex in central dysphagia patients by using blood oxygen level-dependent functional magnetic resonance imaging techniques. The results showed that when normal controls swallowed, primary motor cortex (BA4, insula (BA13, premotor cortex (BA6/8, supramarginal gyrus (BA40, and anterior cingulate cortex (BA24/32 were activated, and that the size of the activated areas were larger in the left hemisphere compared with the right. In recurrent cerebral infarction patients with central dysphagia, BA4, BA13, BA40 and BA6/8 areas were activated, while the degree of activation in BA24/32 was decreased. Additionally, more areas were activated, including posterior cingulate cortex (BA23/31, visual association cortex (BA18/19, primary auditory cortex (BA41 and parahippocampal cortex (BA36. Somatosensory association cortex (BA7 and left cerebellum in patients with recurrent cerebral infarction with central dysphagia were also activated. Experimental findings suggest that the cerebral cortex has obvious hemisphere lateralization in response to swallowing, and patients with recurrent cerebral infarction with central dysphagia show compensatory recombination phenomena of neurological functions. In rehabilitative treatment, using the favorite food of patients can stimulate swallowing through visual, auditory, and other nerve conduction pathways, thus promoting compensatory recombination of the central cortex functions.

  4. Functional MRI neurofeedback training on connectivity between two regions induces long-lasting changes in intrinsic functional network

    Directory of Open Access Journals (Sweden)

    Fukuda eMegumi

    2015-03-01

    Full Text Available Motor or perceptual learning is known to influence functional connectivity between brain regions and induce short-term changes in the intrinsic functional networks revealed as correlations in slow blood-oxygen-level dependent (BOLD signal fluctuations. However, no cause-and-effect relationship has been elucidated between a specific change in connectivity and a long-term change in global networks. Here, we examine the hypothesis that functional connectivity (i.e. temporal correlation between two regions is increased and preserved for a long time when two regions are simultaneously activated or deactivated. Using the connectivity-neurofeedback training paradigm, subjects successfully learned to increase the correlation of activity between the lateral parietal and primary motor areas, regions that belong to different intrinsic networks and negatively correlated before training under the resting conditions. Furthermore, whole-brain hypothesis-free analysis as well as functional network analyses demonstrated that the correlation in the resting state between these areas as well as the correlation between the intrinsic networks that include the areas increased for at least two months. These findings indicate that the connectivity-neurofeedback training can cause long-term changes in intrinsic connectivity and that intrinsic networks can be shaped by experience-driven modulation of regional correlation.

  5. Susceptibility Contrast in High Field MRI of Human Brain as a Function of Tissue Iron Content

    OpenAIRE

    Yao, Bing; Li, Tie-Qiang; van Gelderen, Peter; Shmueli, Karin; de Zwart, Jacco A.; Duyn, Jeff H

    2008-01-01

    Magnetic susceptibility provides an important contrast mechanism for MRI. Increasingly, susceptibility-based contrast is being exploited to investigate brain tissue microstructure and to detect abnormal levels of brain iron as these have been implicated in a variety of neuro-degenerative diseases. However, it remains unclear to what extent magnetic susceptibility-related contrast at high field relates to actual brain iron concentrations. In this study, we performed susceptibility weighted ima...

  6. Functional brain imaging

    International Nuclear Information System (INIS)

    Functional magnetic resonance imaging (fMRI) is a non-invasive method that has become one of the major tools for understanding human brain function and in recent years has also been developed for clinical applications. Changes in hemodynamic signals correspond to changes in neuronal activity with good spatial and temporal resolution in fMRI. Using high-field MR systems and increasingly dedicated statistics and postprocessing, activated brain areas can be detected and superimposed on anatomical images. Currently, fMRI data are often combined in multimodal imaging, e. g. with diffusion tensor imaging (DTI) sequences. This method is helping to further understand the physiology of cognitive brain processes and is also being used in a number of clinical applications. In addition to the blood oxygenation level-dependent (BOLD) signals, this article deals with the construction of fMRI investigations, selection of paradigms and evaluation in the clinical routine. Clinically, this method is mainly used in the planning of brain surgery, analyzing the location of brain tumors in relation to eloquent brain areas and the lateralization of language processing. As the BOLD signal is dependent on the strength of the magnetic field as well as other limitations, an overview of recent developments is given. Increases of magnetic field strength (7 T), available head coils and advances in MRI analytical methods have led to constant improvement in fMRI signals and experimental design. Especially the depiction of eloquent brain regions can be done easily and quickly and has become an essential part of presurgical planning. (orig.)

  7. Determining contrast sensitivity functions for monochromatic light emitted by high-brightness LEDs

    Science.gov (United States)

    Ramamurthy, Vasudha; Narendran, Nadarajah; Freyssinier, Jean Paul; Raghavan, Ramesh; Boyce, Peter

    2004-01-01

    Light-emitting diode (LED) technology is becoming the choice for many lighting applications that require monochromatic light. However, one potential problem with LED-based lighting systems is uneven luminance patterns. Having a uniform luminance distribution is more important in some applications. One example where LEDs are becoming a viable alternative and luminance uniformity is an important criterion is backlighted monochromatic signage. The question is how much uniformity is required for these applications. Presently, there is no accepted metric that quantifies luminance uniformity. A recent publication proposed a method based on digital image analysis to quantify beam quality of reflectorized halogen lamps. To be able to employ such a technique to analyze colored beams generated by LED systems, it is necessary to have contrast sensitivity functions (CSFs) for monochromatic light produced by LEDs. Several factors including the luminance, visual field size, and spectral power distribution of the light affect the CSFs. Although CSFs exist for a variety of light sources at visual fields ranging from 2 degrees to 20 degrees, CSFs do not exist for red, green, and blue light produced by high-brightness LEDs at 2-degree and 10-degree visual fields and at luminances typical for backlighted signage. Therefore, the goal of the study was to develop a family of CSFs for 2-degree and 10-degree visual fields illuminated by narrow-band LEDs at typical luminances seen in backlighted signs. The details of the experiment and the results are presented in this manuscript.

  8. Brain Functional and Structural Predictors of Language Performance.

    Science.gov (United States)

    Skeide, Michael A; Brauer, Jens; Friederici, Angela D

    2016-05-01

    The relation between brain function and behavior on the one hand and the relation between structural changes and behavior on the other as well as the link between the 2 aspects are core issues in cognitive neuroscience. It is an open question, however, whether brain function or brain structure is the better predictor for age-specific cognitive performance. Here, in a comprehensive set of analyses, we investigated the direct relation between hemodynamic activity in 2 pairs of frontal and temporal cortical areas, 2 long-distance white matter fiber tracts connecting each pair and sentence comprehension performance of 4 age groups, including 3 groups of children between 3 and 10 years as well as young adults. We show that the increasing accuracy of processing complex sentences throughout development is correlated with the blood-oxygen-level-dependent activation of 2 core language processing regions in Broca's area and the posterior portion of the superior temporal gyrus. Moreover, both accuracy and speed of processing are correlated with the maturational status of the arcuate fasciculus, that is, the dorsal white matter fiber bundle connecting these 2 regions. The present data provide compelling evidence for the view that brain function and white matter structure together best predict developing cognitive performance. PMID:25770126

  9. Platelet serotonin transporter function predicts default-mode network activity.

    Directory of Open Access Journals (Sweden)

    Christian Scharinger

    Full Text Available The serotonin transporter (5-HTT is abundantly expressed in humans by the serotonin transporter gene SLC6A4 and removes serotonin (5-HT from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence.A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (Vmax was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD activity and platelet Vmax.The present study demonstrates that increases in platelet Vmax significantly predict default-mode network (DMN suppression in healthy subjects independent of genetic variation within SLC6A4. Furthermore, functional connectivity analyses indicate that platelet Vmax is related to global DMN activation and not intrinsic DMN connectivity.This study provides evidence that platelet Vmax predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal Vmax coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation.

  10. Visualization of group inference data in functional neuroimaging.

    Science.gov (United States)

    Gläscher, Jan

    2009-01-01

    While thresholded statistical parametric maps can convey an accurate account for the location and spatial extent of an effect in functional neuroimaging studies, their use is somewhat limited for characterizing more complex experimental effects, such as interactions in a factorial design. The resulting necessity for plotting the underlying data has long been recognized. Statistical Parametric Mapping (SPM) is a widely used software package for analyzing functional neuroimaging data that offers a variety of options for visualizing data from first level analyses. However, nowadays, the thrust of the statistical inference lies at the second level thus allowing for population inference. Unfortunately, the options for visualizing data from second level analyses are quite sparse. rfxplot is a new toolbox designed to alleviate this problem by providing a comprehensive array of options for plotting data from within second level analyses in SPM. These include graphs of average effect sizes (across subjects), averaged fitted responses and event-related blood oxygen level-dependent (BOLD) time courses. All data are retrieved from the underlying first level analyses and voxel selection can be tailored to the maximum effect in each subject within a defined search volume. All plot configurations can be easily configured via a graphical user-interface as well as non-interactively via a script. The large variety of plot options renders rfxplot suitable both for data exploration as well as producing high-quality figures for publications. PMID:19140033

  11. Topological organization of the human brain functional connectome across the lifespan

    Directory of Open Access Journals (Sweden)

    Miao Cao

    2014-01-01

    Full Text Available Human brain function undergoes complex transformations across the lifespan. We employed resting-state functional MRI and graph-theory approaches to systematically chart the lifespan trajectory of the topological organization of human whole-brain functional networks in 126 healthy individuals ranging in age from 7 to 85 years. Brain networks were constructed by computing Pearson's correlations in blood-oxygenation-level-dependent temporal fluctuations among 1024 parcellation units followed by graph-based network analyses. We observed that the human brain functional connectome exhibited highly preserved non-random modular and rich club organization over the entire age range studied. Further quantitative analyses revealed linear decreases in modularity and inverted-U shaped trajectories of local efficiency and rich club architecture. Regionally heterogeneous age effects were mainly located in several hubs (e.g., default network, dorsal attention regions. Finally, we observed inverse trajectories of long- and short-distance functional connections, indicating that the reorganization of connectivity concentrates and distributes the brain's functional networks. Our results demonstrate topological changes in the whole-brain functional connectome across nearly the entire human lifespan, providing insights into the neural substrates underlying individual variations in behavior and cognition. These results have important implications for disease connectomics because they provide a baseline for evaluating network impairments in age-related neuropsychiatric disorders.

  12. Impact of Iodinated Contrast on Renal Function and Hemodynamics in Rats with Chronic Hyperglycemia and Chronic Kidney Disease

    Science.gov (United States)

    Fernandes, Sheila Marques; Martins, Daniel Malisani; da Fonseca, Cassiane Dezoti; Watanabe, Mirian; Vattimo, Maria de Fátima Fernandes

    2016-01-01

    Iodinated contrast (IC) is clinically used in diagnostic and interventional procedures, but its use can result in contrast-induced acute kidney injury (CI-AKI). Chronic kidney disease (CKD) and chronic hyperglycemia (CH) are important predisposing factors to CI-AKI. The aim of this study was to investigate the impact of iodinated contrast on the renal function and hemodynamics in rats with chronic hyperglycemia and chronic kidney disease. A total of 30 rats were divided into six groups; Sham: control of chronic renal disease; Citrate: control of chronic hyperglycemia (CH); Nx5/6: rats with 5/6 nephrectomy; Chronic Hyperglycemia: rats receiving Streptozotocin 65 mg/kg; Nx5/6 + IC: rats Nx5/6 received 6 mL/kg of IC; CH + IC: Chronic hyperglycemia rats receiving 6 mL/kg of IC. Renal function (inulin clearance; urinary neutrophil gelatinase-associated lipocalin, NGAL) and hemodynamics (arterial blood pressure; renal blood flow; renal vascular resistance) were evaluated. Iodinated contrast significantly increased urinary NGAL and reduced inulin clearance, while the hemodynamics parameters showed changes in arterial blood pressure, renal blood flow, and renal vascular resistance in both CKD and CH groups. The results suggest that the iodinated contrast in risk factors models has important impact on renal function and hemodynamics. NGAL was confirmed to play a role of highlight in diagnosis of CI-AKI. PMID:27034930

  13. Advantages of cluster analysis for multifunctional and intercrossing brain area distribution Evaluation by functional magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    Hongchang Zhai; Xudong Xu; Shengyong Xiao

    2008-01-01

    BACKGROUND: Multiple linear regression, general linear test and calculation of correlation values are commonly used in studies of brain function using functional magnetic resonance imaging (fMRI). However, there are some limitations in their applications. In non-signal data statistics, cluster analysis functions as a very mature method, but it is not reliable in signal data statistics. OBJECTIVE: To investigate the spatial distribution of complex function in brain areas during motor tasks by cluster analysis, and to compare this with multiple linear regression. DESIGN, TIME AND SETTING: Block design, performed at the MR laboratory of Guangzhou University of Chinese Medicine. PARTICIPANTS: Fifteen right-handed, healthy university students (10 males and 5 females, aged 19-21 years).METHODS: fMRI was performed while the subjects performed a finger movement task with the right hand. The screen showed a gray hand, with red spots presented in a random order on one of the index, middle, ring and little fingers. The subjects were required to remember the sequence of the red spots on the display. After a delay of 14 seconds, the subjects tapped their fingers according to the order of the red spots, as soon as the red spots turned green. After an interval of 14 seconds, another sequence appeared. Every sequence lasted for 28 seconds, including preparation and execution phases. A total of nine sequences per subject were performed. The data were analyzed using deconvolution and cluster methods, and program "cluster" was used to statistically analyze the coordinate positions of deconvolution and cluster data. MAIN OUTCOME MEASURES: Brain activation maps by deconvolution and brain function maps by clustering of the maximum peak values; blood oxygenation level dependent curves by deconvolution; coordinates of peak values and activation volumes by the two methods. RESULTS: The deconvolution method could not integrate the brain activation maps during different tasks into one

  14. Average arterial input function for quantitative dynamic contrast enhanced magnetic resonance imaging of neck nodal metastases

    International Nuclear Information System (INIS)

    The present study determines the feasibility of generating an average arterial input function (Avg-AIF) from a limited population of patients with neck nodal metastases to be used for pharmacokinetic modeling of dynamic contrast-enhanced MRI (DCE-MRI) data in clinical trials of larger populations. Twenty patients (mean age 50 years [range 27–77 years]) with neck nodal metastases underwent pretreatment DCE-MRI studies with a temporal resolution of 3.75 to 7.5 sec on a 1.5T clinical MRI scanner. Eleven individual AIFs (Ind-AIFs) met the criteria of expected enhancement pattern and were used to generate Avg-AIF. Tofts model was used to calculate pharmacokinetic DCE-MRI parameters. Bland-Altman plots and paired Student t-tests were used to describe significant differences between the pharmacokinetic parameters obtained from individual and average AIFs. Ind-AIFs obtained from eleven patients were used to calculate the Avg-AIF. No overall significant difference (bias) was observed for the transfer constant (Ktrans) measured with Ind-AIFs compared to Avg-AIF (p = 0.20 for region-of-interest (ROI) analysis and p = 0.18 for histogram median analysis). Similarly, no overall significant difference was observed for interstitial fluid space volume fraction (ve) measured with Ind-AIFs compared to Avg-AIF (p = 0.48 for ROI analysis and p = 0.93 for histogram median analysis). However, the Bland-Altman plot suggests that as Ktrans increases, the Ind-AIF estimates tend to become proportionally higher than the Avg-AIF estimates. We found no statistically significant overall bias in Ktrans or ve estimates derived from Avg-AIF, generated from a limited population, as compared with Ind-AIFs. However, further study is needed to determine whether calibration is needed across the range of Ktrans. The Avg-AIF obtained from a limited population may be used for pharmacokinetic modeling of DCE-MRI data in larger population studies with neck nodal metastases. Further validation of the Avg

  15. Influence of contrasting environments on seed composition of two quinoa genotypes: nutritional and functional properties

    Directory of Open Access Journals (Sweden)

    Margarita Miranda

    2013-06-01

    Full Text Available Quinoa (Chenopodium quinoa Willd. in Chile represents a source of germplasm with high nutritional value. However, there is little information available related to quinoa seed quality grown under contrasting environments. In this study we evaluated the changes on seed composition of seeds of two lowland/coastal quinoa genotypes grown under arid (Vicuna and cold-temperate (Temuco conditions in Chile. Results showed that in the case of 'Regalona Baer' and 'Villarrica' genotypes the arid location (with irrigation led to a significant increase (P < 0.05 in grain yield (4.2 and 5.1 t ha-1, respectively, soluble dietary fiber (16.8 ± 0.4 and 28.9 ± 2.1 g kg-1 DM, respectively, vitamin B3 (2.44 ± 0.005 and 2.26 ± 0.04 mg 100 g-1 DM, respectively, saponins (3.22 ± 0.38 mg 100 g-1 DM, 'Regalona Baer', phenolic compounds (19.2 ± 5.48 and 31.92 ± 1.14 mg gallic acid 100 g-1 DM, respectively and components of proximate analysis, except protein content. The cold-temperate climate (rainfed affected positively seed size (2.22 ± 0.17 mm 'Villarrica' and 1000 seed weight (3.08 ± 0.08 and 3.29 ± 0.08 g, respectively, as well as insoluble dietary fiber content (112.3 ± 23.8 g kg-1 DM, 'Regalona Baer'. Furthermore, vitamin C was higher in 'Regalona Baer' genotype at arid locality (31.22 ± 4.2 mg 100 g-1 DM, but much higher content was registered in 'Villarrica' genotype at cold-temperate climate (49.3 ± 5.36 mg 100 g-1 DM. The environment-induced relationship among variables and genotypes was consistent with principal component analysis (PCA. The arid region of Vicuna in Chile represents a potential area for quinoa cultivation for lowland/coastal quinoa genotypes, whose nutritional and functional features were affected positively, due to the much more stressing climatic conditions.

  16. Changes in Renal Function in Elderly Patients Following Intravenous Iodinated Contrast Administration: A Retrospective Study

    International Nuclear Information System (INIS)

    Contrast-induced nephropathy (CIN) is a recognised complication of intravascular administration of iodinated contrast media (ICM). Previous studies suggest a higher incidence in the elderly, but no large study has assessed this to date. We set out to assess changes in creatinine in elderly inpatients following computed tomography (CT) examination and compare those who received intravenous contrast to those who did not. Methods. Using the Radiology Information System in two teaching hospitals, inpatients over the age of seventy who had a CT examination and a baseline creatinine were identified and their follow-up creatinine levels were analysed. Elderly inpatients who underwent a non contrast CT over the same period were used as controls. Results. 677 elderly inpatients who received ICM were compared with 487 controls. 9.2% of patients who received ICM developed acute kidney injury (AKI) compared to 3.5% of inpatient controls (Ρ<0.0001). Patients with higher baseline eGFR had a higher incidence of post-CT AKI. Conclusions. The incidence of post-CT AKI is higher in patients who received IV ICM compared to those who did not; the difference may be partly attributable to contrast-induced nephropathy. This suggests that the incidence of CIN in the elderly may not be as high as previously thought.

  17. Atypically diffuse functional connectivity between caudate nuclei and cerebral cortex in autism

    Directory of Open Access Journals (Sweden)

    Turner Katherine C

    2006-10-01

    Full Text Available Abstract Background Autism is a neurodevelopmental disorder affecting sociocommunicative behavior, but also sensorimotor skill learning, oculomotor control, and executive functioning. Some of these impairments may be related to abnormalities of the caudate nuclei, which have been reported for autism. Methods Our sample was comprised of 8 high-functioning males with autism and 8 handedness, sex, and age-matched controls. Subjects underwent functional MRI scanning during performance on simple visuomotor coordination tasks. Functional connectivity MRI (fcMRI effects were identified as interregional blood oxygenation level dependent (BOLD signal cross-correlation, using the caudate nuclei as seed volumes. Results In the control group, fcMRI effects were found in circuits with known participation of the caudate nuclei (associative, orbitofrontal, oculomotor, motor circuits. Although in the autism group fcMRI effects within these circuits were less pronounced or absent, autistic subjects showed diffusely increased connectivity mostly in pericentral regions, but also in brain areas outside expected anatomical circuits (such as visual cortex. Conclusion These atypical connectivity patterns may be linked to developmental brain growth disturbances recently reported in autism and suggest inefficiently organized functional connectivity between caudate nuclei and cerebral cortex, potentially accounting for stereotypic behaviors and executive impairments.

  18. Combined Cognitive-Psychological-Physical Intervention Induces Reorganization of Intrinsic Functional Brain Architecture in Older Adults

    Directory of Open Access Journals (Sweden)

    Zhiwei Zheng

    2015-01-01

    Full Text Available Mounting evidence suggests that enriched mental, physical, and socially stimulating activities are beneficial for counteracting age-related decreases in brain function and cognition in older adults. Here, we used functional magnetic resonance imaging (fMRI to demonstrate the functional plasticity of brain activity in response to a combined cognitive-psychological-physical intervention and investigated the contribution of the intervention-related brain changes to individual performance in healthy older adults. The intervention was composed of a 6-week program of combined activities including cognitive training, Tai Chi exercise, and group counseling. The results showed improved cognitive performance and reorganized regional homogeneity of spontaneous fluctuations in the blood oxygen level-dependent (BOLD signals in the superior and middle temporal gyri, and the posterior lobe of the cerebellum, in the participants who attended the intervention. Intriguingly, the intervention-induced changes in the coherence of local spontaneous activity correlated with the improvements in individual cognitive performance. Taken together with our previous findings of enhanced resting-state functional connectivity between the medial prefrontal cortex and medial temporal lobe regions following a combined intervention program in older adults, we conclude that the functional plasticity of the aging brain is a rather complex process, and an effective cognitive-psychological-physical intervention is helpful for maintaining a healthy brain and comprehensive cognition during old age.

  19. Auditory cortical responses evoked by pure tones in healthy and sensorineural hearing loss subjects: functional MRI and magnetoencephalography

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yun-ting; GENG Zuo-jun; ZHANG Quan; LI Wei; ZHANG Jing

    2006-01-01

    Background Blood oxygen level dependent functional magnetic resonance imaging (fMRI) and magnetoencephalography are new techniques of brain functional imaging which can provide the information of excitation of neurons by measure the changes of hemodynamics and electrophysiological data of local brain tissue. The purpose of this study was to study functional brain areas evoked by pure tones in healthy and sensorineural hearing loss subjects with these techniques and to compare the differences between the two groups.Methods Thirty healthy and 30 sensorineural hearing loss subjects were included in this study. In fMRI,block-design paradigm was used. During the active epoch the participants listened to 1000 Hz, sound pressure level 140 dB pure tones at duration 500 ms, interstimulus interval 1000 ms, which presented continuously via a magnetic resonance-compatible audio system. None stimulus was executed in control epoch. In magnetoencephalography study, every subject received stimuli of 1000 Hz tone bursts delivered to the bilateral ear at duration 8 ms, interstimulus intervals 1000 ms. Sound pressure level in healthy subjects was 30 dB; in sensorineural hearing loss subjects was 20 dB above everyone' s hearing threshold respectively. All subjects were examined with 306-channel whole-scalp neuromagnetometer.Results In fMRI, all subjects showed significant activations in bilateral Heschl's gyri, anterior pole of planum temporale, planum temporale, precentral gyri, postcentral gyri, supramarginal gyri, superior temporal gyri,inferior frontal gyri, occipital lobes and cerebellums. The healthy subjects had more intensive activation in bilateral Heschl's gyri, anterior pole of planum temporale, inferior frontal gyri, left superior temporal gyri and fight planum temporale than the hearing loss subjects. But in precentral gyri, postcentral gyri and occipital lobes,the activation is more intensive in the hearing loss subjects. In magnetoencephalography study, both in the

  20. Comparison of contrast enhanced three dimensional echocardiography with MIBI gated SPECT for the evaluation of left ventricular function

    Directory of Open Access Journals (Sweden)

    Cosyns Bernard

    2009-06-01

    Full Text Available Abstract Background In clinical practice and in clinical trials, echocardiography and scintigraphy are used the most for the evaluation of global left ejection fraction (LVEF and left ventricular (LV volumes. Actually, poor quality imaging and geometrical assumptions are the main limitations of LVEF measured by echocardiography. Contrast agents and 3D echocardiography are new methods that may alleviate these potential limitations. Methods Therefore we sought to examine the accuracy of contrast 3D echocardiography for the evaluation of LV volumes and LVEF relative to MIBI gated SPECT as an independent reference. In 43 patients addressed for chest pain, contrast 3D echocardiography (RT3DE and MIBI gated SPECT were prospectively performed on the same day. The accuracy and the variability of LV volumes and LVEF measurements were evaluated. Results Due to good endocardial delineation, LV volumes and LVEF measurements by contrast RT3DE were feasible in 99% of the patients. The mean LV end-diastolic volume (LVEDV of the group by scintigraphy was 143 ± 65 mL and was underestimated by triplane contrast RT3DE (128 ± 60 mL; p Conclusion Contrast RT3DE allows an accurate assessment of LVEF compared to the LVEF measured by SPECT, and shows low variability between observers. Although RT3DE triplane provides accurate evaluation of left ventricular function, RT3DE full-volume is superior to triplane modality in patients with suspected coronary artery disease.

  1. New noninvasive assessment of regional left ventricular function by digital subtraction angiography without the use of contrast medium

    International Nuclear Information System (INIS)

    We have developed a new noninvasive method to evaluate regional left ventricular (LV) function by digital subtraction angiography (DSA) without the use of contrast medium. DSA images of the left ventricle with and without contrast medium were obtained from 35 patients with anterior myocardial infarction (MI) and from 35 control subjects. Using an image-processing computer, regional LV time-density curves were constructed for one cardiac cycle. Regional LV time-density curves obtained from DSA without the use of contrast medium presented a pattern similar to those from intravenous DSA. The amplitude of regional LV time-density curves in patients with MI decreased along with increasing severity of regional wall motion abnormality assessed by conventional left ventriculography. In attempting semi-quantitative evaluation by DSA without the use of contrast medium, the regional wall motion index (RWI) in the 6 segments of the left ventricle was calculated by normalizing segmental density changes to the maximal segmental density changes. When compared with control subjects, patients with MI have significantly lower RWIs in the anterolateral and apical regions. RWI showed a good correlation with the regional ejection fraction (REF) obtained from intravenous contrast DSA (r=0.83). RWI decreased with increasing severity of regional wall motion abnormality by qualitative analysis in conventional left ventriculography, being consistent with REF. The diagnostic accuracy of RWI therefore seemed to be comparable to that of REF derived from intravenous contrast DSA. These results indicate that computerized analysis of DSA without the use of contrast medium is a valuable noninvasive method for semi-quantitative assessment of regional LV function. (author)

  2. Functional MRI study of mild Alzheimer's disease using amplitude of low frequency fluctuation analysis

    Institute of Scientific and Technical Information of China (English)

    XI Qian; ZHAO Xiao-hu; WANG Pei-jun; GUO Qi-hao; YAN Chao-gan; HE Yong

    2012-01-01

    Background Previous studies have shown that the functional brain activity in the resting state is impaired in Alzheimer's disease (AD) patients.However,most studies focused on the relationship between different brain areas,rather than the amplitude or strength of the regional brain activity.The purpose of this study was to explore the functional brain changes in AD patients by measuring the amplitude of the blood oxygenation level dependent (BOLD) functional MRI (fMRI) signals.Methods Twenty mild AD patients and twenty healthy elderly subjects participated in the fMRI scan.The amplitude of low frequency fluctuation (ALFF) was calculated using REST software.Results Compared with the healthy elderly subjects,the mild AD patients showed decreased ALFF in the right posterior cingulate cortex,right ventral medial prefrontal cortex,and in the bilateral dorsal medial prefrontal cortex.No brain region with increased ALFF was found in the AD group compared with the control group.Conclusions The reduced activity in the posterior cingulate cortex and medial prefrontal cortex observed in the present study suggest that the functional abnormalities of those areas are at an early stage of AD.The ALFF analysis may provide a useful tool in fMRI study of AD.

  3. Neural Changes following Behavioral Activation for a Depressed Breast Cancer Patient: A Functional MRI Case Study

    Directory of Open Access Journals (Sweden)

    Michael J. Gawrysiak

    2012-01-01

    Full Text Available Functional neuroimaging is an innovative but at this stage underutilized method to assess the efficacy of psychotherapy for depression. Functional magnetic resonance imaging (fMRI was used in this case study to examine changes in brain activity in a depressed breast cancer patient receiving an 8-session Behavioral Activation Treatment for Depression (BATD, based on the work of Hopko and Lejuez (2007. A music listening paradigm was used during fMRI brain scans to assess reward responsiveness at pre- and posttreatment. Following treatment, the patient exhibited attenuated depression and changes in blood oxygenation level dependence (BOLD response in regions of the prefrontal cortex and the subgenual cingulate cortex. These preliminary findings outline a novel means to assess psychotherapy efficacy and suggest that BATD elicits functional brain changes in areas implicated in the pathophysiology of depression. Further research is necessary to explore neurobiological mechanisms of change in BATD, particularly the potential mediating effects of reward responsiveness and associated brain functioning.

  4. Relationship of Visual Cortex Function and Visual Acuity in Anisometropic Amblyopic Children

    Directory of Open Access Journals (Sweden)

    Chuanming Li, Lin Cheng, Qiongwu Yu, Bing Xie, Jian Wang

    2012-01-01

    Full Text Available Purpose: To detect the functional deficit of the visual cortex in anisometropic amblyopia children using functional magnetic resonance imaging (fMRI technique, and investigate the relationship between visual acuity and visual cortex function.Methods: Blood oxygenation level-dependent fMRI (BOLD-fMRI was performed in ten monocular anisometropic amblyopia children and ten normal controls. fMRI images were acquired in two runs with visual stimulation delivered separately through the sound and amblyopic eyes. Measurements were performed in cortical activation of striate and extrastriate areas at the occipital lobe. The relationship between cortex function and visual acuity was analyzed by Pearson partial analysis.Results: The activation areas of both the striate and extrastriate cortices in the amblyopic eyes were significantly lower than that of the sound fellow eyes. No relationship was found between the striate and extrastriate cortex activation. No relationship was found between the visual cortical activation of striate, extrastriate areas and visual acuity of anisometropic amblyopes.Conclusions: BOLD-fMRI revealed the independent striate and extrastriate cortical deficits in anisometropic amblyopes. In addition, the visual acuity lesion and the striate and extrastriate cortical deficits were not parallel, and results of fMRI examination have much potential value in the evaluation of amblyopia.

  5. Visualizing functional pathways in the human brain using correlation tensors and magnetic resonance imaging.

    Science.gov (United States)

    Ding, Zhaohua; Xu, Ran; Bailey, Stephen K; Wu, Tung-Lin; Morgan, Victoria L; Cutting, Laurie E; Anderson, Adam W; Gore, John C

    2016-01-01

    Functional magnetic resonance imaging usually detects changes in blood oxygenation level dependent (BOLD) signals from T2*-sensitive acquisitions, and is most effective in detecting activity in brain cortex which is irrigated by rich vasculature to meet high metabolic demands. We recently demonstrated that MRI signals from T2*-sensitive acquisitions in a resting state exhibit structure-specific temporal correlations along white matter tracts. In this report we validate our preliminary findings and introduce spatio-temporal functional correlation tensors to characterize the directional preferences of temporal correlations in MRI signals acquired at rest. The results bear a remarkable similarity to data obtained by diffusion tensor imaging but without any diffusion-encoding gradients. Just as in gray matter, temporal correlations in resting state signals may reflect intrinsic synchronizations of neural activity in white matter. Here we demonstrate that functional correlation tensors are able to visualize long range white matter tracts as well as short range sub-cortical fibers imaged at rest, and that evoked functional activities alter these structures and enhance the visualization of relevant neural circuitry. Furthermore, we explore the biophysical mechanisms underlying these phenomena by comparing pulse sequences, which suggest that white matter signal variations are consistent with hemodynamic (BOLD) changes associated with neural activity. These results suggest new ways to evaluate MRI signal changes within white matter. PMID:26477562

  6. Exploring the feasibility of simultaneous electroencephalography/functional magnetic resonance imaging at 7 T.

    Science.gov (United States)

    Mullinger, Karen; Brookes, Matthew; Stevenson, Claire; Morgan, Paul; Bowtell, Richard

    2008-09-01

    The increased blood oxygenation level-dependent contrast available at high field makes the implementation of combined EEG/fMRI experiments at 7 T highly worthwhile from the point of view of fMRI data quality, but the higher field poses greater technical challenges for achieving good quality EEG data. A study of the feasibility of recording EEG signals from human subjects at 7 T using a commercially available, MR-compatible EEG system has therefore been carried out. This involved systematic measurement of the sources of noise in EEG recordings made in the 7 T scanner and measurement of RF heating effects on a gel phantom in the presence of a 32-electrode EEG cap. Having found no significant safety concerns and identified a set-up (involving switching off the magnet's cryo-cooler pumps and mounting the EEG amplifier on a cantilever) that limited scanner-induced noise, combined EEG/fMRI experiments employing visual stimulation were then successfully carried out on two human subjects. With the use of beamformer-based analysis of the EEG data, driven responses and alpha-band, event-related desynchronisation were identified in both subjects. PMID:18508217

  7. Indices of adrenal deficiency involved in brain plasticity and functional control reorganization in hemodialysis patients with polysulfone membrane: BOLD-fMRI study.

    Science.gov (United States)

    Belaïch, Rachida; Boujraf, Saïd; Benzagmout, Mohammed; Maaroufi, Mustapha; Housni, Abdelkhalek; Batta, Fatima; Tizniti, Siham; Magoul, Rabia; Sqalli, Tarik

    2016-06-01

    This work purpose was to estimate the implication of suspected adrenal function deficiencies, which was influenced by oxidative stress (OS) that are generating brain plasticity, and reorganization of the functional control. This phenomenon was revealed in two-hemodialysis patients described in this paper. Blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) revealed a significant activation of the motor cortex. Hemodialysis seems to originate an inflammatory state of the cerebral tissue reflected by increased OS, while expected to decrease since hemodialysis eliminates free radicals responsible for OS. Considering adrenal function deficiencies, sensitivity to OS and assessed hyponatremia and hypercalcemia, adrenal function deficiencies is strongly suspected in both patients. This probably contributes to amplify brain plasticity and a reorganization of functional control after hemodialysis that is compared to earlier reported studies. Brain plasticity and functional control reorganization was revealed by BOLD-fMRI with a remarkable sensitivity. Brain plastic changes are originated by elevated OS associating indices of adrenal function deficiencies. These results raise important issues about adrenal functional deficiencies impact on brain plasticity in chronic hemodialysis-patients. This motivates more global studies of plasticity induced factors in this category of patients including adrenal functional deficiencies and OS. PMID:27301905

  8. Quantitative Assessment of Right Ventricular Systolic Function by the Analysis of Right Ventricular Contrast Time-intensity Curve

    Institute of Scientific and Technical Information of China (English)

    王林; 邓又斌; 李天亮; 杨好意

    2004-01-01

    To study reliability and reliable indices of quantitative assessment of right ventricular systolic function by time-intensity curve (TIC)with right ventricular contrast, 5 % sonicated human albumin was injected intravenously at a does of 0. 08 ml/kg into 10 dogs at baseline status and cardiac insufficiency. Apical four-chamber view was observed for washinand washout of contrast agent from right ventricle. The parameters of TIC were obtained by curve fitting. The differences of parameters were analyzed in different states of cardiac functions. Among the parameters derived from TIC, the time constant (k) was decreased significantly with decline of cardiac function(P<0.001). But half-time of decent of peak intensity (HT) and mean-transit-time (MTT) of washout were increased significantly (P<0. 001). The k was strongly related to cardiac output of right ventricle (CO) and ejection fraction (EF) of left ventricle and fractional shortening (FS)of left ventricle. Right ventricular systolic function could be assessed reliably by the parameters derived from TIC with right ventricular contrast echocardiography. The k, HT and MTT are reliable indices for quantitative assessment of right ventricular systolic function.

  9. Detecting Visual Function Abnormality with a Contrast-Dependent Visual Test in Patients with Type 2 Diabetes.

    Science.gov (United States)

    Tsai, Li-Ting; Liao, Kuo-Meng; Jang, Yuh; Hu, Fu-Chang; Wu, Wei-Chi

    2016-01-01

    In addition to diabetic retinopathy, diabetes also causes early retinal neurodegeneration and other eye problems, which cause various types of visual deficits. This study used a computer-based visual test (Macular Multi-Function Assessment (MMFA)) to assess contrast-dependent macular visual function in patients with type 2 diabetes to collect more visual information than possible with only the visual acuity test. Because the MMFA is a newly developed test, this study first compared the agreement and discriminative ability of the MMFA and the Early Treatment Diabetic Retinopathy Study (ETDRS) contrast acuity charts. Then symbol discrimination performances of diabetic patients and controls were evaluated at 4 contrast levels using the MMFA. Seventy-seven patients and 45 controls participated. The agreement between MMFA and ETDRS scores was examined by fitting three-level linear mixed-effect models to estimate the intraclass correlation coefficients (ICCs). The estimated areas under the receiver operating characteristic (ROC) curve were used to compare the discriminative ability of diseased versus non-diseased participants between the two tests. The MMFA scores of patients and controls were compared with multiple linear regression analysis after adjusting the effects of age, sex, hypertension and cataract. Results showed that the scores of the MMFA and ETDRS tests displayed high levels of agreement and acceptable and similar discriminative ability. The MMFA performance was correlated with the severity of diabetic retinopathy. Most of the MMFA scores differed significantly between the diabetic patients and controls. In the low contrast condition, the MMFA scores were significantly lower for 006Eon-DR patients than for controls. The potential utility of the MMFA as an easy screening tool for contrast-dependent visual function and for detecting early functional visual change in patients with type 2 diabetes is discussed. PMID:27611680

  10. Polarization tensors of planar domains as functions of the admittivity contrast

    OpenAIRE

    Griesmaier, Roland; Hanke, Martin

    2014-01-01

    (Electric) polarization tensors describe part of the leading order term of asymptotic voltage perturbations caused by low volume fraction inhomogeneities of the electrical properties of a medium. They depend on the geometry of the support of the inhomogeneities and on their admittivity contrast. Corresponding asymptotic formulas are of particular interest in the design of reconstruction algorithms for determining the locations and the material properties of inhomogeneities inside a body from ...

  11. Metal Oxide Nanoparticles for Contrast Enhancement in Magnetic Resonance Imaging : Synthesis, Functionalization and Characterization

    OpenAIRE

    Ahrén, Maria

    2013-01-01

    This thesis work focuses on the design and production of nanoparticle based contrast agents for signal enhancement in magnetic resonance imaging (MRI). Three different synthesis routes are explored, primarily to produce crystalline gadolinium oxide (Gd2O3) nanoparticles, and surface modification is done to obtain stable, dispersible, biocompatible probes inducing high proton relaxivities. In Paper I and II we utilized the polyol synthesis method and nanoparticle purification was performed wit...

  12. Estimates of the Planet Yield from Ground-Based High-Contrast Imaging Observations as a Function of Stellar Mass

    CERN Document Server

    Crepp, Justin R

    2011-01-01

    We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar-neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into account the important factors that govern the likelihood for imaging a planet, including the statistical properties of nearby stars, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys and express the resulting yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date. Using the most recent empirical findings for the occurrence rate of planets from RV surveys, our simulations indicate that extrapolation of the Doppler planet population to separations accessible to high-contrast instruments provides excellent agreement bet...

  13. Functional brain imaging; Funktionelle Hirnbildgebung

    Energy Technology Data Exchange (ETDEWEB)

    Gizewski, E.R. [Medizinische Universitaet Innsbruck, Universitaetsklinik fuer Neuroradiologie, Innsbruck (Austria)

    2016-02-15

    Functional magnetic resonance imaging (fMRI) is a non-invasive method that has become one of the major tools for understanding human brain function and in recent years has also been developed for clinical applications. Changes in hemodynamic signals correspond to changes in neuronal activity with good spatial and temporal resolution in fMRI. Using high-field MR systems and increasingly dedicated statistics and postprocessing, activated brain areas can be detected and superimposed on anatomical images. Currently, fMRI data are often combined in multimodal imaging, e. g. with diffusion tensor imaging (DTI) sequences. This method is helping to further understand the physiology of cognitive brain processes and is also being used in a number of clinical applications. In addition to the blood oxygenation level-dependent (BOLD) signals, this article deals with the construction of fMRI investigations, selection of paradigms and evaluation in the clinical routine. Clinically, this method is mainly used in the planning of brain surgery, analyzing the location of brain tumors in relation to eloquent brain areas and the lateralization of language processing. As the BOLD signal is dependent on the strength of the magnetic field as well as other limitations, an overview of recent developments is given. Increases of magnetic field strength (7 T), available head coils and advances in MRI analytical methods have led to constant improvement in fMRI signals and experimental design. Especially the depiction of eloquent brain regions can be done easily and quickly and has become an essential part of presurgical planning. (orig.) [German] Mittlerweile ist die funktionelle MRT (fMRT) eine Methode, die nicht mehr nur in der neurowissenschaftlichen Routine verwendet wird. Die fMRT ermoeglicht die nichtinvasive Darstellung der Hirnaktivitaet in guter raeumlicher und zeitlicher Aufloesung unter Ausnutzung der Durchblutungsaenderung aufgrund der erhoehten Nervenzellaktivitaet. Unter

  14. Development of a large-scale functional brain network during human non-rapid eye movement sleep.

    Science.gov (United States)

    Spoormaker, Victor I; Schröter, Manuel S; Gleiser, Pablo M; Andrade, Katia C; Dresler, Martin; Wehrle, Renate; Sämann, Philipp G; Czisch, Michael

    2010-08-25

    Graph theoretical analysis of functional magnetic resonance imaging (fMRI) time series has revealed a small-world organization of slow-frequency blood oxygen level-dependent (BOLD) signal fluctuations during wakeful resting. In this study, we used graph theoretical measures to explore how physiological changes during sleep are reflected in functional connectivity and small-world network properties of a large-scale, low-frequency functional brain network. Twenty-five young and healthy participants fell asleep during a 26.7 min fMRI scan with simultaneous polysomnography. A maximum overlap discrete wavelet transformation was applied to fMRI time series extracted from 90 cortical and subcortical regions in normalized space after residualization of the raw signal against unspecific sources of signal fluctuations; functional connectivity analysis focused on the slow-frequency BOLD signal fluctuations between 0.03 and 0.06 Hz. We observed that in the transition from wakefulness to light sleep, thalamocortical connectivity was sharply reduced, whereas corticocortical connectivity increased; corticocortical connectivity subsequently broke down in slow-wave sleep. Local clustering values were closest to random values in light sleep, whereas slow-wave sleep was characterized by the highest clustering ratio (gamma). Our findings support the hypothesis that changes in consciousness in the descent to sleep are subserved by reduced thalamocortical connectivity at sleep onset and a breakdown of general connectivity in slow-wave sleep, with both processes limiting the capacity of the brain to integrate information across functional modules. PMID:20739559

  15. Global Functional Connectivity Differences between Sleep-Like States in Urethane Anesthetized Rats Measured by fMRI

    Science.gov (United States)

    Paasonen, Jaakko; Shatillo, Artem; Lipponen, Arto; Salo, Raimo; Aliev, Rubin; Tanila, Heikki; Gröhn, Olli

    2016-01-01

    Sleep is essential for nervous system functioning and sleep disorders are associated with several neurodegenerative diseases. However, the macroscale connectivity changes in brain networking during different sleep states are poorly understood. One of the hindering factors is the difficulty to combine functional connectivity investigation methods with spontaneously sleeping animals, which prevents the use of numerous preclinical animal models. Recent studies, however, have implicated that urethane anesthesia can uniquely induce different sleep-like brain states, resembling rapid eye movement (REM) and non-REM (NREM) sleep, in rodents. Therefore, the aim of this study was to assess changes in global connectivity and topology between sleep-like states in urethane anesthetized rats, using blood oxygenation level dependent (BOLD) functional magnetic resonance imaging. We detected significant changes in corticocortical (increased in NREM-like state) and corticothalamic connectivity (increased in REM-like state). Additionally, in graph analysis the modularity, the measure of functional integration in the brain, was higher in NREM-like state than in REM-like state, indicating a decrease in arousal level, as in normal sleep. The fMRI findings were supported by the supplementary electrophysiological measurements. Taken together, our results show that macroscale functional connectivity changes between sleep states can be detected robustly with resting-state fMRI in urethane anesthetized rats. Our findings pave the way for studies in animal models of neurodegenerative diseases where sleep abnormalities are often one of the first markers for the disorder development. PMID:27168145

  16. Global Functional Connectivity Differences between Sleep-Like States in Urethane Anesthetized Rats Measured by fMRI.

    Directory of Open Access Journals (Sweden)

    Ekaterina Zhurakovskaya

    Full Text Available Sleep is essential for nervous system functioning and sleep disorders are associated with several neurodegenerative diseases. However, the macroscale connectivity changes in brain networking during different sleep states are poorly understood. One of the hindering factors is the difficulty to combine functional connectivity investigation methods with spontaneously sleeping animals, which prevents the use of numerous preclinical animal models. Recent studies, however, have implicated that urethane anesthesia can uniquely induce different sleep-like brain states, resembling rapid eye movement (REM and non-REM (NREM sleep, in rodents. Therefore, the aim of this study was to assess changes in global connectivity and topology between sleep-like states in urethane anesthetized rats, using blood oxygenation level dependent (BOLD functional magnetic resonance imaging. We detected significant changes in corticocortical (increased in NREM-like state and corticothalamic connectivity (increased in REM-like state. Additionally, in graph analysis the modularity, the measure of functional integration in the brain, was higher in NREM-like state than in REM-like state, indicating a decrease in arousal level, as in normal sleep. The fMRI findings were supported by the supplementary electrophysiological measurements. Taken together, our results show that macroscale functional connectivity changes between sleep states can be detected robustly with resting-state fMRI in urethane anesthetized rats. Our findings pave the way for studies in animal models of neurodegenerative diseases where sleep abnormalities are often one of the first markers for the disorder development.

  17. Visual contrast sensitivity in patients with impairment of functional independence after stroke

    OpenAIRE

    dos Santos Natanael; Andrade Suellen

    2012-01-01

    Abstract Background Stroke has been considered a serious public health problem in many countries, accounting for complex disorders involving perception, such as visual, cognitive and functional deficits. The impact of stroke on the visual perception of individuals with impairments in functional independence was investigated. Methods We measured changes in functional independence and visual function in 40 patients with stroke (M = 52.3, SD = 0.65) and 10 controls (M = 52.5, SD = 0.66). The pat...

  18. Correlations Between the Gradient of Contrast Density, Evaluated by Cardio CT, and Functional Significance of Coronary Artery Stenosis

    Directory of Open Access Journals (Sweden)

    Orzan Marius

    2016-06-01

    Full Text Available Background: Assessment of the hemodynamic significance of a coronary artery stenosis is a challenging task, being extremely important for the establishment of indication for revascularization in atherosclerotic coronary artery stenosis. The aim of this study was to evaluate the role of a new marker reflecting the functional significance of a coronary artery stenosis, represented by the attenuation degree of contrast density along the stenosis by Coronary CT.

  19. [Functional connectivity analysis of the brain network using resting-state FMRI].

    Science.gov (United States)

    Hayashi, Toshihiro

    2011-12-01

    Spatial patterns of spontaneous fluctuations in blood oxygenation level-dependent (BOLD) signals reflect the underlying neural architecture. The study of the brain network based on these self-organized patterns is termed resting-state functional MRI (fMRI). This review article aims at briefly reviewing a basic concept of this technology and discussing its implications for neuropsychological studies. First, the technical aspects of resting-state fMRI, including signal sources, physiological artifacts, image acquisition, and analytical methods such as seed-based correlation analysis and independent component analysis, are explained, followed by a discussion on the major resting-state networks, including the default mode network. In addition, the structure-function correlation studied using diffuse tensor imaging and resting-state fMRI is briefly discussed. Second, I have discussed the reservations and potential pitfalls of 2 major imaging methods: voxel-based lesion-symptom mapping and task fMRI. Problems encountered with voxel-based lesion-symptom mapping can be overcome by using resting-state fMRI and evaluating undamaged brain networks in patients. Regarding task fMRI in patients, I have also emphasized the importance of evaluating the baseline brain activity because the amplitude of activation in BOLD fMRI is hard to interpret as the same baseline cannot be assumed for both patient and normal groups. PMID:22147450

  20. Functional connectivity analysis of the brain network using resting-state fMRI

    International Nuclear Information System (INIS)

    Spatial patterns of spontaneous fluctuations in blood oxygenation level-dependent (BOLD) signals reflect the underlying neural architecture. The study of the brain network based on these self-organized patterns is termed resting-state functional MRI (fMRI). This review article aims at briefly reviewing a basic concept of this technology and discussing its implications for neuropsychological studies. First, the technical aspects of resting-state fMRI, including signal sources, physiological artifacts, image acquisition, and analytical methods such as seed-based correlation analysis and independent component analysis, are explained, followed by a discussion on the major resting-state networks, including the default mode network. In addition, the structure-function correlation studied using diffuse tensor imaging and resting-state fMRI is briefly discussed. Second, I have discussed the reservations and potential pitfalls of 2 major imaging methods: voxel-based lesion-symptom mapping and task fMRI. Problems encountered with voxel-based lesion-symptom mapping can be overcome by using resting-state fMRI and evaluating undamaged brain networks in patients. Regarding task fMRI in patients, I have also emphasized the importance of evaluating the baseline brain activity because the amplitude of activation in BOLD fMRI is hard to interpret as the same baseline cannot be assumed for both patient and normal groups. (author)

  1. Sensitivity of the resting-state haemodynamic response function estimation to autonomic nervous system fluctuations.

    Science.gov (United States)

    Wu, Guo-Rong; Marinazzo, Daniele

    2016-05-13

    The haemodynamic response function (HRF) is a key component of the blood oxygen level-dependent (BOLD) signal, providing the mapping between neural activity and the signal measured with functional magnetic resonance imaging (fMRI). Most of the time the HRF is associated with task-based fMRI protocols, in which its onset is explicitly included in the design matrix. On the other hand, the HRF also mediates the relationship between spontaneous neural activity and the BOLD signal in resting-state protocols, in which no explicit stimulus is taken into account. It has been shown that resting-state brain dynamics can be characterized by looking at sparse BOLD 'events', which can be retrieved by point process analysis. These events can be then used to retrieve the HRF at rest. Crucially, cardiac activity can also induce changes in the BOLD signal, thus affecting both the number of these events and the estimation of the haemodynamic response. In this study, we compare the resting-state haemodynamic response retrieved by means of a point process analysis, taking the cardiac fluctuations into account. We find that the resting-state HRF estimation is significantly modulated in the brainstem and surrounding cortical areas. From the analysis of two high-quality datasets with different temporal and spatial resolution, and through the investigation of intersubject correlation, we suggest that spontaneous point process response durations are associated with the mean interbeat interval and low-frequency power of heart rate variability in the brainstem. PMID:27044997

  2. Normothermic Mouse Functional MRI of Acute Focal Thermostimulation for Probing Nociception

    Science.gov (United States)

    Reimann, Henning Matthias; Hentschel, Jan; Marek, Jaroslav; Huelnhagen, Till; Todiras, Mihail; Kox, Stefanie; Waiczies, Sonia; Hodge, Russ; Bader, Michael; Pohlmann, Andreas; Niendorf, Thoralf

    2016-01-01

    Combining mouse genomics and functional magnetic resonance imaging (fMRI) provides a promising tool to unravel the molecular mechanisms of chronic pain. Probing murine nociception via the blood oxygenation level-dependent (BOLD) effect is still challenging due to methodological constraints. Here we report on the reproducible application of acute noxious heat stimuli to examine the feasibility and limitations of functional brain mapping for central pain processing in mice. Recent technical and procedural advances were applied for enhanced BOLD signal detection and a tight control of physiological parameters. The latter includes the development of a novel mouse cradle designed to maintain whole-body normothermia in anesthetized mice during fMRI in a way that reflects the thermal status of awake, resting mice. Applying mild noxious heat stimuli to wildtype mice resulted in highly significant BOLD patterns in anatomical brain structures forming the pain matrix, which comprise temporal signal intensity changes of up to 6% magnitude. We also observed sub-threshold correlation patterns in large areas of the brain, as well as alterations in mean arterial blood pressure (MABP) in response to the applied stimulus.

  3. Functional MRI study of verbal working memory in children with attention deficit hyperactivity disorder

    International Nuclear Information System (INIS)

    Objective: To study the verbal working memory of children with attention deficit hyperactivity disorder (ADHD) as well as to explore the characteristics of functional areas of verbal working memory with blood oxygenation level dependent functional magnetic resonance imaging (fMRI). Method: Eighteen children were selected in the study. There were 9 ADHD children with inattention subtype and 9 healthy subjects. All patients and healthy subjects completed the cognitive examination and the block- designed N-block verbal working memory task using a GE 3.0 T MR. Data were analyzed by AFNI software. Result: The neural activations of ADHD's children are lower than that of control under verbal working memory. Especially in the areas of bilateral middle frontal gyri and inferior frontal gyri, bilateral superior parietal lobules and inferior parietal lobules, right basal ganglia in the 1-BACK task. And bilateral middle frontal gyri and inferior frontal gyri, bilateral superior parietal lobules, left cortex inferior parietallobule, right basal ganglia, anterior cingulatecortex in the 2-BACK task. Conclusion: The hypofunctional areas of verbal working memory (including bilateral dorsolateral prefrontal cortex and parietal cortex) can be seen in the ADHD children especially who also has lower activation of anterior cingulate cortex under 2-BACK task. (authors)

  4. Working memory dysfunction associated with brain functional deficits and cellular metabolic changes in patients with generalized anxiety disorder.

    Science.gov (United States)

    Moon, Chung-Man; Sundaram, Thirunavukkarasu; Choi, Nam-Gil; Jeong, Gwang-Woo

    2016-08-30

    Generalized anxiety disorder (GAD) is associated with brain functional and morphological changes in connected with emotional dysregulation and cognitive deficit. This study dealt with the neural functional deficits and metabolic abnormalities in working memory (WM) task with emotion-inducing distractors in patients with GAD. Fourteen patients with GAD and 14 healthy controls underwent functional magnetic resonance imaging (fMRI) and proton magnetic resonance spectroscopy ((1)H-MRS) at 3T. In response to the emotional distractors in WM tasks, the patients concurrently showed higher activity in the hippocampus and lower activities in the superior occipital gyrus, superior parietal gyrus, dorsolateral prefrontal cortex (DLPFC) and precentral gyrus compared to the controls. MRS revealed significantly lower choline/creatine (Cho/Cr) and choline/N-acetylaspartate (Cho/NAA) ratios in the DLPFC. In particular, the Cho ratios were positively correlated with the brain activities based on blood oxygenation level-dependent signal change in the DLPFC. This study provides the first evidence for the association between the metabolic alterations and functional deficit in WM processing with emotion-inducing distractors in GAD. These findings will be helpful to understand the neural dysfunction in connection with WM impairment in GAD. PMID:27442922

  5. Life in Oligotropic Desert Environments: Contrasting Taxonomic and Functional Diversity of Two Microbial Mats with Metagenomics

    Science.gov (United States)

    Bonilla-Rosso, G.; Peimbert, M.; Olmedo, G.; Alcaraz, L. D.; Eguiarte, L. E.; Souza, V.

    2010-04-01

    The metagenomic analysis of two microbial mats from the oligotrophic waters in the Cuatrociéngas basin reveals large differences both at taxonomic and functional level. These are explained in terms of environmental stability and nutrient availability.

  6. Imaging vascular function for early stage clinical trials using dynamic contrast-enhanced magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Leach, M.O.; Orton, M. [Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Cancer Research UK and EPSRC Cancer Imaging Centre, Sutton, Surrey (United Kingdom); Morgan, B. [Univ. of Leicester, College of Medicine, Biological Sciences and Psychology, Leicester (United Kingdom); Tofts, P.S. [Brighton and Sussex Medical School, Univ. of Sussex, Clinical Imaging Sciences Centre, Sussex (United Kingdom); Buckley, D.L. [University of Leeds, Division of Medical Physics, Leeds (United Kingdom); Huang, W. [Oregon Health and Science Univ., Advanced Imaging Research Centre, Portland, OR (United States); Horsfield, M.A. [Medical Physics Section, Leicester Royal Infirmary, Dept. of Cardiovascular Sciences, Leicester (United Kingdom); Chenevert, T.L. [Univ. of Michigan Health System, Ann Arbor, MI (United States); Collins, D.J. [Royal Marsden Hospital NHS Foundation Trust, Cancer Research UK and EPSRC Cancer Imaging Centre, Sutton, Surrey (United Kingdom); Jackson, A. [Univ. of Manchester, Wolfson Molecular Imaging Centre, Withington, Manchester, M20 3LJ (United Kingdom); Lomas, D. [Univ. of Cambridge, Dept. of Radiology, Cambridge (United Kingdom); Whitcher, B. [Unit 2 Greenways Business Park, Mango Solutions, Chippenham (United Kingdom); Clarke, L. [Cancer Imaging Program, Imaging Technology Development Branch, Rockville, MD (United States); Plummer, R. [Univ. of Newcastle Upon Tyne, The Medical School, Medical Oncology, Northern Inst. for Cancer Research, Newcastle Upon Tyne (United Kingdom); Judson, I. [Royal Marsden Hospital, Sutton, Surrey (United Kingdom); Jones, R. [Beatson West of Scotland Cancer Centre, Glasgow (United Kingdom); Alonzi, R. [Mount Vernon Cancer Centre, Northwood (United Kingdom); Brunner, T. [Gray Inst. for Radiation, Oncology and Biology, Oxford (United Kingdom); Koh, D.M. [Royal Marsden NHS Foundation Trust, Diagnostic Radiology, Sutton, Surrey (United Kingdom)] [and others

    2012-07-15

    Many therapeutic approaches to cancer affect the tumour vasculature, either indirectly or as a direct target. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has become an important means of investigating this action, both pre-clinically and in early stage clinical trials. For such trials, it is essential that the measurement process (i.e. image acquisition and analysis) can be performed effectively and with consistency among contributing centres. As the technique continues to develop in order to provide potential improvements in sensitivity and physiological relevance, there is considerable scope for between-centre variation in techniques. A workshop was convened by the Imaging Committee of the Experimental Cancer Medicine Centres (ECMC) to review the current status of DCE-MRI and to provide recommendations on how the technique can best be used for early stage trials. This review and the consequent recommendations are summarised here. (orig.)

  7. Imaging vascular function for early stage clinical trials using dynamic contrast-enhanced magnetic resonance imaging

    International Nuclear Information System (INIS)

    Many therapeutic approaches to cancer affect the tumour vasculature, either indirectly or as a direct target. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has become an important means of investigating this action, both pre-clinically and in early stage clinical trials. For such trials, it is essential that the measurement process (i.e. image acquisition and analysis) can be performed effectively and with consistency among contributing centres. As the technique continues to develop in order to provide potential improvements in sensitivity and physiological relevance, there is considerable scope for between-centre variation in techniques. A workshop was convened by the Imaging Committee of the Experimental Cancer Medicine Centres (ECMC) to review the current status of DCE-MRI and to provide recommendations on how the technique can best be used for early stage trials. This review and the consequent recommendations are summarised here. (orig.)

  8. Functional connectivity in the default network during resting state is preserved in a vegetative but not in a brain dead patient.

    Science.gov (United States)

    Boly, M; Tshibanda, L; Vanhaudenhuyse, A; Noirhomme, Q; Schnakers, C; Ledoux, D; Boveroux, P; Garweg, C; Lambermont, B; Phillips, C; Luxen, A; Moonen, G; Bassetti, C; Maquet, P; Laureys, S

    2009-08-01

    Recent studies on spontaneous fluctuations in the functional MRI blood oxygen level-dependent (BOLD) signal in awake healthy subjects showed the presence of coherent fluctuations among functionally defined neuroanatomical networks. However, the functional significance of these spontaneous BOLD fluctuations remains poorly understood. By means of 3 T functional MRI, we demonstrate absent cortico-thalamic BOLD functional connectivity (i.e. between posterior cingulate/precuneal cortex and medial thalamus), but preserved cortico-cortical connectivity within the default network in a case of vegetative state (VS) studied 2.5 years following cardio-respiratory arrest, as documented by extensive behavioral and paraclinical assessments. In the VS patient, as in age-matched controls, anticorrelations could also be observed between posterior cingulate/precuneus and a previously identified task-positive cortical network. Both correlations and anticorrelations were significantly reduced in VS as compared to controls. A similar approach in a brain dead patient did not show any such long-distance functional connectivity. We conclude that some slow coherent BOLD fluctuations previously identified in healthy awake human brain can be found in alive but unaware patients, and are thus unlikely to be uniquely due to ongoing modifications of conscious thoughts. Future studies are needed to give a full characterization of default network connectivity in the VS patients population. PMID:19350563

  9. Radiological functional analysis of the vascular system contrast media, methods, results

    CERN Document Server

    1983-01-01

    Scientists and engineers have been involved in medical radiology from the very beginning. At times advances in this field occur at a tremen­ dously fast pace. Developments in radiological diagnostics have - technologically and medically speaking - focused on morphology. At present, computer-aided tomography (CAT) is at a high point in deve1opment, medical application, and validation. The preconditions for this success were rapid advances in electronics and computer technology - in hardware and in software - and an unexpected cost reduction in these fields; the co operation of various scientific disci­ plines was also essential. Functional radiological diagnosis has been neglected in part, owing to the emphasis on morphology, but alone the synthesis of morphology and function prornises further advances. Apart from the limited capabilities ofuItrasonic techniques there is no way other than using X-rays to carry out functional studies of organs and their systems through an intact body surface. It is frequently...

  10. Altered regional homogeneity in post-traumatic stress disorder: a resting-state functional magnetic resonance imaging study

    Institute of Scientific and Technical Information of China (English)

    Yan Yin; Baoci Shan; Qiyong Gong; Lingjiang Li; Changfeng Jin; Lisa T.Eyler; Hua Jin; Xiaolei Hu; Lian Duan; Huirong Zheng; Bo Feng; Xuanyin Huang

    2012-01-01

    Objective Little is known about the brain systems that contribute to vulnerability to post-traumatic stress disorder (PTSD).Comparison of the resting-state patterns of intrinsic functional synchronization,as measured by functional magnetic resonance imaging (fMRI),between groups with and without PTSD following a traumatic event can help identify the neural mechanisms of the disorder and targets for intervention.Methods Fifty-four PTSD patients and 72 matched traumatized subjects who experienced the 2008 Sichuan earthquake were imaged with blood oxygen level-dependent (BOLD) fMRI and analyzed using the measure of regional homogeneity (ReHo) during the resting state.Results PTSD patients presented enhanced ReHo in the left inferior parietal lobule and right superior frontal gyrus,and reduced ReHo in the right middle temporal gyrus and lingual gyrus,relative to traumatized individuals without PTSD.Conclusion Our findings showed that abnormal brain activity exists under resting conditions in PTSD patients who had been exposed to a major earthquake.Alterations in the local functional connectivity of cortical regions are likely to contribute to the neural mechanisms underlying PTSD.

  11. No difference in frontal cortical activity during an executive functioning task after acute doses of aripiprazole and haloperidol

    Directory of Open Access Journals (Sweden)

    Ingeborg eBolstad

    2015-05-01

    Full Text Available Background: Aripiprazole is an atypical antipsychotic drug that is characterized by partial dopamine D2 receptor agonism. Its pharmacodynamic profile is proposed to be beneficial in the treatment of cognitive impairment, which is prevalent in psychotic disorders. This study compared brain activation characteristics produced by aripiprazole with that of haloperidol, a typical D2 receptor antagonist, during a task targeting executive functioning.Methods: Healthy participants received an acute oral dose of haloperidol, aripiprazole or placebo before performing an executive functioning task while blood-oxygen-level-dependent (BOLD functional magnetic resonance imaging (fMRI was carried out. Results: There was a tendency towards reduced performance in the aripiprazole group compared to the two other groups. The image analysis yielded a strong task-related BOLD-fMRI response within each group. An uncorrected between-group analysis showed that aripiprazole challenge resulted in stronger activation in the frontal and temporal gyri and the putamen compared with haloperidol challenge, but after correcting for multiple testing there was no significant group difference. Conclusion: No significant group differences between aripiprazole and haloperidol in frontal cortical activation were obtained when corrected for multiple comparisons.This study is registered in ClinicalTrials.gov (identifier: 2009-016222-14; https://clinicaltrials.gov/.

  12. Abnormal Functional MRI BOLD Contrast in the Vegetative State after Severe Traumatic Brain Injury

    Science.gov (United States)

    Heelmann, Volker

    2010-01-01

    For the rehabilitation process, the treatment of patients surviving brain injury in a vegetative state is still a serious challenge. The aim of this study was to investigate patients exhibiting severely disturbed consciousness using functional magnetic resonance imaging. Five cases of posttraumatic vegetative state and one with minimal…

  13. The effects of sleep deprivation on brain functioning in older adults.

    Science.gov (United States)

    Almklov, Erin L; Drummond, Sean P A; Orff, Henry; Alhassoon, Omar M

    2015-01-01

    Few studies have examined the effects of total sleep deprivation (TSD) on cognitive performance and brain activation using functional MRI (fMRI) in older adults. The current study examines blood oxygen level-dependent (BOLD) activation in older adults and younger adults during the sustained attention (GO) and response inhibition (NOGO) portions of a GO-NOGO cognitive task following 36 hr of total sleep deprivation. No significant performance differences were observed between the groups on the behavioral outcome measures of total hits and false alarms. Neuroimaging results, however, revealed a significant interaction between age-group and sleep-deprivation status. Specifically, older adults showed greater BOLD activation as compared to younger adults after 36 hours total sleep deprivation in brain regions typically associated with attention and inhibitory processes. These results suggest in order for older adults to perform the GO-NOGO task effectively after sleep deprivation, they rely on compensatory recruitment of brain regions that aide in the maintenance of cognitive performance. PMID:24787041

  14. Factors related to the magnitude of T2* MR signal changes during functional imaging

    Energy Technology Data Exchange (ETDEWEB)

    Krings, T. [Department of Neuroradiology, University Hospital of the Technical University Aachen (Germany); Department of Neurosurgery, University Hospital of the Technical University Aachen (Germany); Interdisciplinary Centre for Clinical Research - Central Nervous System, University Hospital of the Technical University Aachen, Pauwelsstrasse 30, 52057 Aachen (Germany); Reinges, M.H.T.; Gilsbach, J.M. [Department of Neurosurgery, University Hospital of the Technical University Aachen (Germany); Willmes, K.; Nuerk, H.C. [Section of Neuropsychology, Department of Neurology, University Hospital of the Technical University Aachen (Germany); Meister, I.G. [Department of Neurology, University Hospital of the Technical University Aachen (Germany); Thron, A. [Department of Neuroradiology, University Hospital of the Technical University Aachen (Germany)

    2002-06-01

    Our aim was to determine whether age, sex, the degree of weakness, anticonvulsants, the histology of the underlying lesion(s), the presence of oedema or the distance of the lesion from the motor region have an impact on the blood oxygenation level-dependent (BOLD) signal strength and therefore on the validity of functional MRI (fMRI). We studied 98 patients with masses near the central region imaged for surgical planning at 1.5 tesla, employing a BOLD sequence during a motor task. We calculated percentage signal change in the primary motor cortex between rest and activation and carried out multiple linear regression to examine the impact of the above factors on signal strength. Using a stepwise analysis strategy, the distance of the lesion from the motor region had the strongest influence (r=0.653, P<0.001). The factor with largest uncorrelated additional impact on signal change was the presence of oedema. Both predictors together formed a highly significant multiple r=0.739 (P<0.001). No other predictive factor was identified (all P>0.20). Disturbances of cerebral blood flow and metabolism induced by the tumour were presumed to be the causes of a decrease in signal in the adjacent cortex. (orig.)

  15. Functional and anatomical basis for brain plasticity in facial palsy rehabilitation using the masseteric nerve.

    Science.gov (United States)

    Buendia, Javier; Loayza, Francis R; Luis, Elkin O; Celorrio, Marta; Pastor, Maria A; Hontanilla, Bernardo

    2016-03-01

    Several techniques have been described for smile restoration after facial nerve paralysis. When a nerve other than the contralateral facial nerve is used to restore the smile, some controversy appears because of the nonphysiological mechanism of smile recovering. Different authors have reported natural results with the masseter nerve. The physiological pathways which determine whether this is achieved continue to remain unclear. Using functional magnetic resonance imaging, brain activation pattern measuring blood-oxygen-level-dependent (BOLD) signal during smiling and jaw clenching was recorded in a group of 24 healthy subjects (11 females). Effective connectivity of premotor regions was also compared in both tasks. The brain activation pattern was similar for smile and jaw-clenching tasks. Smile activations showed topographic overlap though more extended for smile than clenching. Gender comparisons during facial movements, according to kinematics and BOLD signal, did not reveal significant differences. Effective connectivity results of psychophysiological interaction (PPI) from the same seeds located in bilateral facial premotor regions showed significant task and gender differences (p < 0.001). The hypothesis of brain plasticity between the facial nerve and masseter nerve areas is supported by the broad cortical overlap in the representation of facial and masseter muscles. PMID:26683008

  16. Improved spatial accuracy of functional maps in the rat olfactory bulb using supervised machine learning approach.

    Science.gov (United States)

    Murphy, Matthew C; Poplawsky, Alexander J; Vazquez, Alberto L; Chan, Kevin C; Kim, Seong-Gi; Fukuda, Mitsuhiro

    2016-08-15

    Functional MRI (fMRI) is a popular and important tool for noninvasive mapping of neural activity. As fMRI measures the hemodynamic response, the resulting activation maps do not perfectly reflect the underlying neural activity. The purpose of this work was to design a data-driven model to improve the spatial accuracy of fMRI maps in the rat olfactory bulb. This system is an ideal choice for this investigation since the bulb circuit is well characterized, allowing for an accurate definition of activity patterns in order to train the model. We generated models for both cerebral blood volume weighted (CBVw) and blood oxygen level dependent (BOLD) fMRI data. The results indicate that the spatial accuracy of the activation maps is either significantly improved or at worst not significantly different when using the learned models compared to a conventional general linear model approach, particularly for BOLD images and activity patterns involving deep layers of the bulb. Furthermore, the activation maps computed by CBVw and BOLD data show increased agreement when using the learned models, lending more confidence to their accuracy. The models presented here could have an immediate impact on studies of the olfactory bulb, but perhaps more importantly, demonstrate the potential for similar flexible, data-driven models to improve the quality of activation maps calculated using fMRI data. PMID:27236085

  17. Microstructural brain differences predict functional hemodynamic responses in a reward processing task.

    Science.gov (United States)

    Camara, Estela; Rodriguez-Fornells, Antoni; Münte, Thomas F

    2010-08-25

    Many aspects of human behavior are driven by rewards, yet different people are differentially sensitive to rewards and punishment. In this study, we show that white matter microstructure in the uncinate/inferior fronto-occipital fasciculus, defined by fractional anisotropy values derived from diffusion tensor magnetic resonance images, correlates with both short-term (indexed by the fMRI blood oxygenation level-dependent response to reward in the nucleus accumbens) and long-term (indexed by the trait measure sensitivity to punishment) reactivity to rewards. Moreover, trait measures of reward processing were also correlated with reward-related functional activation in the nucleus accumbens. The white matter tract revealed by the correlational analysis connects the anterior temporal lobe with the medial and lateral orbitofrontal cortex and also supplies the ventral striatum. The pattern of strong correlations suggests an intimate relationship between white matter structure and reward-related behavior that may also play a role in a number of pathological conditions, such as addiction and pathological gambling. PMID:20739561

  18. Atlas-based multichannel monitoring of functional MRI signals in real-time: automated approach.

    Science.gov (United States)

    Lee, Jong-Hwan; O'Leary, Heather M; Park, Hyunwook; Jolesz, Ferenc A; Yoo, Seung-Schik

    2008-02-01

    We report an automated method to simultaneously monitor blood-oxygenation-level-dependent (BOLD) MR signals from multiple cortical areas in real-time. Individual brain anatomy was normalized and registered to a pre-segmented atlas in standardized anatomical space. Subsequently, using real-time fMRI (rtfMRI) data acquisition, localized BOLD signals were measured and displayed from user-selected areas labeled with anatomical and Brodmann's Area (BA) nomenclature. The method was tested on healthy volunteers during the performance of hand motor and internal speech generation tasks employing a trial-based design. Our data normalization and registration algorithm, along with image reconstruction, movement correction and a data display routine were executed with enough processing and communication bandwidth necessary for real-time operation. Task-specific BOLD signals were observed from the hand motor and language areas. One of the study participants was allowed to freely engage in hand clenching tasks, and associated brain activities were detected from the motor-related neural substrates without prior knowledge of the task onset time. The proposed method may be applied to various applications such as neurofeedback, brain-computer-interface, and functional mapping for surgical planning where real-time monitoring of region-specific brain activity is needed. PMID:17370340

  19. In search of specificity: functional MRI in the study of emotional experience.

    Science.gov (United States)

    Schienle, Anne; Schäfer, Axel

    2009-07-01

    The growing availability of functional magnetic resonance imaging (fMRI) with its property of high spatial resolution has energized the search for specific neural substrates of basic emotions and their feeling components. In the present article, we address the question as to whether recent fMRI studies on primary affective experiences have truly helped to pinpoint emotion-specific areas in the human brain or whether these studies are afflicted with methodological problems which make such inferences difficult. As one approach for improvement, we suggest the combination of fMRI with methods characterized by high temporal resolution, such as electroencephalography (EEG). Simultaneous recoding allows the correlation of temporally specific EEG components (e.g., the late positive potential) with regional blood-oxygen-level-dependent (BOLD) signals during affective experiences. Combined information on the source as well as the exact temporal pattern of a neural affective response will help to improve our understanding of emotion-specific brain activation. PMID:19530276

  20. Neural correlates of simple unimanual discrete and continuous movements: a functional imaging study at 3 T

    International Nuclear Information System (INIS)

    The cerebral and cerebellar network involved in unimanual continuous and discrete movements was studied in blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) at 3 T. Seven healthy right-handed volunteers were scanned (1) while drawing a circle with the tip of the right index finger (continuous motor task), and (2) while drawing a triangle with the tip of the right index finger (discrete motor task). In both motor tasks, extensive activations were observed in the sensorimotor (M1/S1), parietal, prefrontal, insular, lateral occipital (LOC) and anterior cerebellar cortices. Subcortical activations within red, thalamic and lentiform nuclei were also detected. However, discrete movements were specifically followed by the recruitment of the left orbitofrontal cortex, right dentate nucleus and the second cerebellar homunculus (HVIII), and bilateral and stronger activation of the sensorimotor cortical areas, whereas continuous movements specifically activated the right prefrontal cortex and the lateral hemispherical part of the neocerebellum (crus 1). We confirm the findings of previous studies showing partly distinct neural networks involved in monitoring continuous and discrete movements, but we found new differential neural relays within the prefrontal, insular and neocerebellar cortices. (orig.)

  1. Factors related to the magnitude of T2* MR signal changes during functional imaging

    International Nuclear Information System (INIS)

    Our aim was to determine whether age, sex, the degree of weakness, anticonvulsants, the histology of the underlying lesion(s), the presence of oedema or the distance of the lesion from the motor region have an impact on the blood oxygenation level-dependent (BOLD) signal strength and therefore on the validity of functional MRI (fMRI). We studied 98 patients with masses near the central region imaged for surgical planning at 1.5 tesla, employing a BOLD sequence during a motor task. We calculated percentage signal change in the primary motor cortex between rest and activation and carried out multiple linear regression to examine the impact of the above factors on signal strength. Using a stepwise analysis strategy, the distance of the lesion from the motor region had the strongest influence (r=0.653, P0.20). Disturbances of cerebral blood flow and metabolism induced by the tumour were presumed to be the causes of a decrease in signal in the adjacent cortex. (orig.)

  2. Depth-resolved rhodopsin molecular contrast imaging for functional assessment of photoreceptors

    Science.gov (United States)

    Liu, Tan; Wen, Rong; Lam, Byron L.; Puliafito, Carmen A.; Jiao, Shuliang

    2015-09-01

    Rhodopsin, the light-sensing molecule in the outer segments of rod photoreceptors, is responsible for converting light into neuronal signals in a process known as phototransduction. Rhodopsin is thus a functional biomarker for rod photoreceptors. Here we report a novel technology based on visible-light optical coherence tomography (VIS-OCT) for in vivo molecular imaging of rhodopsin. The depth resolution of OCT allows the visualization of the location where the change of optical absorption occurs and provides a potentially accurate assessment of rhodopsin content by segmentation of the image at the location. Rhodopsin OCT can be used to quantitatively image rhodopsin distribution and thus assess the distribution of functional rod photoreceptors in the retina. Rhodopsin OCT can bring significant impact into ophthalmic clinics by providing a tool for the diagnosis and severity assessment of a variety of retinal conditions.

  3. Depth-resolved rhodopsin molecular contrast imaging for functional assessment of photoreceptors

    OpenAIRE

    Tan Liu; Rong Wen; Lam, Byron L.; Puliafito, Carmen A.; Shuliang Jiao

    2015-01-01

    Rhodopsin, the light-sensing molecule in the outer segments of rod photoreceptors, is responsible for converting light into neuronal signals in a process known as phototransduction. Rhodopsin is thus a functional biomarker for rod photoreceptors. Here we report a novel technology based on visible-light optical coherence tomography (VIS-OCT) for in vivo molecular imaging of rhodopsin. The depth resolution of OCT allows the visualization of the location where the change of optical absorption oc...

  4. Using hydrochemical tracers to conceptualise hydrological function in a larger scale catchment draining contrasting geologic provinces

    Science.gov (United States)

    Capell, R.; Tetzlaff, D.; Malcolm, I. A.; Hartley, A. J.; Soulsby, C.

    2011-09-01

    SummaryA year-long multivariate tracer study in the 749 km 2 catchment of the North-Esk in north east Scotland was carried out to infer the dominant runoff generation processes in two markedly different geologic provinces. The upper 60% of the catchment has montane headwaters dominated by impermeable metamorphic rocks, steep topography, peaty soils and a sub-arctic climate with over 1400 mm of precipitation. The lowlands of the catchment are underlain by a major sandstone aquifer, and mainly have freely draining, fertile soils that support intensive arable farming under a drier climate with around 800 mm of precipitation. Storm runoff in the uplands is dominated by near-surface processes in soils and sedimentary layers which generate around 60% of annual stream flows with water of low alkalinity and ionic strength. In contrast, tributaries in the lower parts of the catchment are dominated by groundwater-fed base flows which account for 75% of annual runoff and are characterised by alkaline waters with high concentrations of base cations and high levels of nitrate. Multivariate statistical methods were used to derive a generic typology of catchment source waters, their spatial and temporal dynamics and particularly, how they integrate together at the larger catchment scale. The uplands dominate the winter high flow response of the whole catchment. The influence of lowland groundwater from major aquifers becomes more apparent under low flows. However, groundwater from small upland aquifers plays a critical role for ecosystem service in dry periods providing baseflows which dilute pollutant inputs from lowland areas at the large catchment scale.

  5. Facile Synthesis of Gd-Functionalized Gold Nanoclusters as Potential MRI/CT Contrast Agents

    OpenAIRE

    Wenjun Le; Shaobin Cui; Xin Chen; Huanhuan Zhu; Bingdi Chen; Zheng Cui

    2016-01-01

    Multi-modal imaging plays a key role in the earlier detection of disease. In this work, a facile bioinspired method was developed to synthesize Gd-functionalized gold nanoclusters (Gd-Au NCs). The Gd-Au NCs exhibit a uniform size, with an average size of 5.6 nm in dynamic light scattering (DLS), which is a bit bigger than gold clusters (3.74 nm, DLS), while the fluorescent properties of Gd-Au NCs are almost the same as that of Au NCs. Moreover, the Gd-Au NCs exhibit a high longitudinal relaxi...

  6. Cluster size statistic and cluster mass statistic: two novel methods for identifying changes in functional connectivity between groups or conditions.

    Directory of Open Access Journals (Sweden)

    Alex Ing

    Full Text Available Functional connectivity has become an increasingly important area of research in recent years. At a typical spatial resolution, approximately 300 million connections link each voxel in the brain with every other. This pattern of connectivity is known as the functional connectome. Connectivity is often compared between experimental groups and conditions. Standard methods used to control the type 1 error rate are likely to be insensitive when comparisons are carried out across the whole connectome, due to the huge number of statistical tests involved. To address this problem, two new cluster based methods--the cluster size statistic (CSS and cluster mass statistic (CMS--are introduced to control the family wise error rate across all connectivity values. These methods operate within a statistical framework similar to the cluster based methods used in conventional task based fMRI. Both methods are data driven, permutation based and require minimal statistical assumptions. Here, the performance of each procedure is evaluated in a receiver operator characteristic (ROC analysis, utilising a simulated dataset. The relative sensitivity of each method is also tested on real data: BOLD (blood oxygen level dependent fMRI scans were carried out on twelve subjects under normal conditions and during the hypercapnic state (induced through the inhalation of 6% CO2 in 21% O2 and 73%N2. Both CSS and CMS detected significant changes in connectivity between normal and hypercapnic states. A family wise error correction carried out at the individual connection level exhibited no significant changes in connectivity.

  7. Rhodopsin molecular contrast imaging by optical coherence tomography for functional assessment of photoreceptors (Conference Presentation)

    Science.gov (United States)

    Nafra, Zahra; Liu, Tan; Jiao, Shuliang

    2016-03-01

    Rhodopsin, the light-sensing molecule in the outer segments of rod photoreceptors, is responsible for converting light into neuronal signals in a process known as phototransduction. Rhodopsin is thus a functional biomarker for rod photoreceptors. We developed a novel technology based on visible-light optical coherence tomography (VIS-OCT) for in vivo molecular imaging of rhodopsin. The depth resolution of OCT allows the visualization of the location where the change of optical absorption occurs and provides a potentially accurate assessment of rhodopsin content by segmentation of the image at the location. A broadband supercontinuum laser, whose filtered output was centered at 520 nm, was used as the illuminating light source. To test the capabilities of the system on rhodopsin mapping we imaged the retina of albino rats. The rats were dark adapted before imaging. An integrated near infrared OCT was used to guide the alignment in dark. VIS-OCT three-dimensional images were then acquired under dark- and light- adapted states sequentially. Rhodopsin distribution was calculated from the differential image. The rhodopsin distributions can be displayed in both en face view and depth-resolved cross-sectional image. Rhodopsin OCT can be used to quantitatively image rhodopsin distribution and thus assess the distribution of functional rod photoreceptors in the retina. Rhodopsin OCT can bring significant impact into ophthalmic clinics by providing a tool for the diagnosis and severity assessment of a variety of retinal conditions.

  8. Blocked-micropores, surface functionalized, bio-compatible and silica-coated iron oxide nanocomposites as advanced MRI contrast agent

    International Nuclear Information System (INIS)

    Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. In this article, a systematic study of the design and development of surface-modification schemes for silica-coated iron oxide nanoparticles (IONP) via a one-pot, in situ method at room temperature is presented. Silica-coated IONP were prepared in a water-in-oil microemulsion, and subsequently the surface was modified via addition of organosilane reagents to the microemulsion system. The structure and the morphology of the as synthesized nanoparticles have been investigated by means of transmission electron microscopy (TEM) and measurement of N2 adsorption–desorption. Electron diffraction and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the IONP structures. Nitrogen adsorption indicates microporous and blocked-microporous structures for the silica-coated and amine functionalized silica-coated IONP, respectively which could prove less cytotoxicity of the functionalized final product. Besides, the colloidal stability of the final product and the presence of the modified functional groups on top of surface layer have been proven by zeta-potential measurements. Owing to the benefit from the inner IONP core and the hydrophilic silica shell, the as-synthesized nanocomposites were exploited as an MRI contrast enhancement agent. Relaxometric results prove that the surface functionalized IONP have also signal enhancement properties. These surface functionalized nanocomposites are not only potential candidates for highly efficient contrast agents for MRI, but could also be used as ultrasensitive biological-magnetic labels, because they are in nanoscale size, having magnetic properties, blocked-microporous and are well dispersible in biological environment.

  9. Blocked-micropores, surface functionalized, bio-compatible and silica-coated iron oxide nanocomposites as advanced MRI contrast agent

    Energy Technology Data Exchange (ETDEWEB)

    Darbandi, Masih, E-mail: masih.darbandi@uni-due.de [Vanderbilt University, Department of Physics and Vanderbilt Institute of Nanoscale Science and Engineering (VINSE) (United States); Laurent, Sophie [University of Mons, Department of General, Organic and Biomedical Chemistry NMR and Molecular Imaging Laboratory (Belgium); Busch, Martin [University of Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Li Zian [University of Duisburg-Essen, Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Yuan Ying; Krueger, Michael [University of Freiburg, Department of Microsystems Engineering and Freiburg Materials Research Centre (Germany); Farle, Michael [University of Duisburg-Essen, Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Winterer, Markus [University of Duisburg-Essen, Nanoparticle Process Technology, Faculty of Engineering and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Vander Elst, Luce; Muller, Robert N. [University of Mons, Department of General, Organic and Biomedical Chemistry NMR and Molecular Imaging Laboratory (Belgium); Wende, Heiko [University of Duisburg-Essen, Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

    2013-05-15

    Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. In this article, a systematic study of the design and development of surface-modification schemes for silica-coated iron oxide nanoparticles (IONP) via a one-pot, in situ method at room temperature is presented. Silica-coated IONP were prepared in a water-in-oil microemulsion, and subsequently the surface was modified via addition of organosilane reagents to the microemulsion system. The structure and the morphology of the as synthesized nanoparticles have been investigated by means of transmission electron microscopy (TEM) and measurement of N{sub 2} adsorption-desorption. Electron diffraction and high-resolution transmission electron microscopic (TEM) images of the nanoparticles showed the highly crystalline nature of the IONP structures. Nitrogen adsorption indicates microporous and blocked-microporous structures for the silica-coated and amine functionalized silica-coated IONP, respectively which could prove less cytotoxicity of the functionalized final product. Besides, the colloidal stability of the final product and the presence of the modified functional groups on top of surface layer have been proven by zeta-potential measurements. Owing to the benefit from the inner IONP core and the hydrophilic silica shell, the as-synthesized nanocomposites were exploited as an MRI contrast enhancement agent. Relaxometric results prove that the surface functionalized IONP have also signal enhancement properties. These surface functionalized nanocomposites are not only potential candidates for highly efficient contrast agents for MRI, but could also be used as ultrasensitive biological-magnetic labels, because they are in nanoscale size, having magnetic properties, blocked-microporous and are well dispersible in biological environment.

  10. Changes in thyroid function following iodine-containing contrast administration in patients in an endemic goitre area

    Energy Technology Data Exchange (ETDEWEB)

    Grehn, S.; Steidle, B.; Seif, F.J.

    1981-08-01

    A prospective study of thyroid function after the administration of iodine-containing radiographic contrast media was carried out on 119 patients from an area where goitres are endemic. Eighteen patients had a negative TRH test after 28 days. Results showed hyperthyroid function in 27.9% of patients after oral cholecystography, 15.1% of patients after intravenous cholangiography and 5.3% of patients after infusion urography. In these patients, thyroxin and triiodothyronin levels were higher than in euthyroid patients. Thyroid stimulating antibodies could not be demonstrated. Induction of hyperthyroidism by iodine is considered to be due to autonomy of the thyroid gland parenchyma. For this reason the risk of iodine-induced hyperthyroidism is greater in patients from a goitre endemic region (by a factor of 1.3 to 17.1).

  11. Evaluation of possible factors affecting contrast sensitivity function in patients with primary Sjögren’s syndrome

    Directory of Open Access Journals (Sweden)

    Sedat Arikan

    2015-06-01

    Full Text Available ABSTRACT Purpose: The contrast sensitivity (CS function in patients with primary Sjögren’s syndrome (pSS may be impaired either frequently as a result of dry eye diseases or rarely as a result of optic neuropathy. In this study, we aimed to evaluate the CS function in pSS patients as well as to assess corneal aberrations and thickness of the peripapillary retinal nerve fiber layer (pRNFL. Methods: Fourteen eyes of 14 pSS patients (pSS group and 14 eyes of 14 healthy participants (control group were subjected to assessment of CS at the spatial frequencies of 1.5, 3.0, 6.0, 12, and 18 cycles/degree (cpd using a functional visual acuity contrast test (FACT; measurement of corneal high-order aberrations (HOAs in terms of coma-like, spherical-like, and total HOAs using Scheimpflug corneal topography; and measurement of the thickness of both the macular ganglion cell-inner plexiform layer (mGCIPL and pRNFL in all quadrants using optical coherence tomography. None of the participants were under treatment with artificial tears. Results: The results of the CS test did not differ between the 2 groups at all spatial frequencies (p>0.05. In addition, there were no statistically significant differences between the 2 groups in terms of corneal HOAs (p>0.05 and thickness of mGCIPL (p>0.05. However, among all quadrants, only the inferior quadrant of pRNFL in pSS patients was statistically significantly thinner than that in the healthy participants (p=0.04. Conclusions: The CS function in pSS patients can be maintained with normal thickness of both pRNFL and mGCIPL and with lack of increased corneal HOAs, which may be present even in the absence of artificial tear usage.

  12. Resurrecting Brinley Plots for a Novel Use: Meta-Analyses of Functional Brain Imaging Data in Older Adults

    Directory of Open Access Journals (Sweden)

    Ann M. Peiffer

    2008-01-01

    Full Text Available By plotting response times of young and older adults across a variety of tasks, Brinley spurred investigation and debate into the theory of general cognitive slowing. Though controversial, Brinley plots can assess between-task differences, the impact of increasing task demand, and the relationship between responses in two groups of subjects. Since a relationship exists between response times and the blood-oxygen level dependent (BOLD signal of functional MRI (fMRI, Brinley's plotting method could be applied as a meta-analysis tool in fMRI studies of aging. Here, fledgling “Peiffer plots” are discussed for their potential impact on understanding general cognitive brain activity in aging. Preliminary results suggest that general cognitive slowing may be localized at the sensorimotor transformation in the precentral gyrus. Although this meta-analysis method is naturally used with imaging studies of aging, theoretically it may be applied to other study pairs (e.g., schizophrenic versus normal or imaging datasets (e.g., PET.

  13. Anatomical and functional overlap within the insula and anterior cingulate cortex during interoception and phobic symptom provocation.

    Science.gov (United States)

    Caseras, Xavier; Murphy, Kevin; Mataix-Cols, David; López-Solà, Marina; Soriano-Mas, Carles; Ortriz, Hector; Pujol, Jesus; Torrubia, Rafael

    2013-05-01

    The anterior insula and the dorsal anterior cingulate cortex (ACC) are regarded as key brain structures associated with the integration of perceived phobic characteristics of external stimuli and the perception of ones own body responses that leads to emotional feelings. To test to what extent the activity in these two brain structures anatomically and functionally overlap during phobic reactions and interoception, we submitted the same group of phobic participants (n = 29; either spider or blood-injection-injury (BII) phobics) and controls (n = 17) to both type of experimental paradigms. Results showed that there was a clear anatomical overlap in the Blood Oxygen Level-Dependent (BOLD) responses within the anterior insula and ACC elicited during phobic symptom provocation and during interoceptive awareness. The activity within these two brain structures also showed to be correlated in the spider phobia group, but not in the BII phobic participants. Our results seem to support the idea that the activity within these two brain areas would be associated with the integration of perceived stimuli characteristics and bodily responses that lead to what we label as "fear." However, that seems not to be the case in BII phobia, where more research is needed in order to clarify to what extent that could be associated with the idiosyncratic physiological response that these patients present in front of phobic stimuli (i.e., drop in heart rate and blood pressure). PMID:22162203

  14. Functional MRI activity in the thalamus and occipital cortex of anesthetized dogs induced by monocular and binocular stimulation.

    Science.gov (United States)

    Willis, C K; Quinn, R P; McDonell, W M; Gati, J; Partlow, G; Vilis, T

    2001-07-01

    The neuroanatomy of the mammalian visual system has received considerable attention through electrophysiological study of cats and non-human primates, and through neuroimaging of humans. Canine neuroanatomy, however, has received much less attention, limiting our understanding of canine vision and visual pathways. As an early step in applying blood oxygenation level dependant (BOLD) functional magnetic resonance imaging (fMRI) for veterinary use, we compared visual activity in the thalamus and occipital cortex of anesthetized dogs presented with binocular and monocular visual stimuli. Activity in the left and right thalamus and occipital cortex during monocular stimulation was also compared. Six beagles were presented with a vertical grating visual stimulus and scanned at 4 Tesla. Each dog was scanned twice under each of 3 anesthetic protocols (isoflurane, propofol, and fentanyl/midazolam). We found: 1) significant BOLD activation in the lateral geniculate nucleus (LGN) of the thalamus and the occipital cortex; 2) a significantly larger area of activation in the LGN during monocular stimulation than during binocular stimulation; and 3) that activity in the hemisphere contralateral to the stimulus was not significantly greater than that ipsilateral to it. PMID:11480525

  15. Neurotransmitter changes during interference task in anterior cingulate cortex: evidence from fMRI-guided functional MRS at 3 T.

    Science.gov (United States)

    Kühn, Simone; Schubert, Florian; Mekle, Ralf; Wenger, Elisabeth; Ittermann, Bernd; Lindenberger, Ulman; Gallinat, Jürgen

    2016-06-01

    Neural activity as indirectly observed in blood oxygenation level-dependent (BOLD) response is thought to reflect changes in neurotransmitter flux. In this study, we used fMRI-guided functional magnetic resonance spectroscopy (MRS) to measure metabolite/BOLD associations during a cognitive task at 3 T. GABA and glutamate concentration in anterior cingulate cortex (ACC) were determined by means of MRS using the SPECIAL pulse sequence before, during and after the performance of a manual Stroop task. MRS voxel positions were centred around individuals' BOLD activity during Stroop performance. Levels of GABA and glutamate showed inverted U-shape patterns across measurement time points (before, during, and after task), glutamine increased linearly and total creatine did not change. The GABA increase during task performance was associated with ACC BOLD signal changes in both congruent and incongruent Stroop conditions. Using an fMRI-guided MRS approach, an association between induced inhibitory neurotransmitter increase and BOLD changes was observed. The proposed procedure might allow the in vivo investigation of normal and dysfunctional associations between neurotransmitters and BOLD signal crucial for cerebral functioning. PMID:25976598

  16. Functional Flow Patterns and Static Blood Pooling in Tumors Revealed by Combined Contrast-Enhanced Ultrasound and Photoacoustic Imaging.

    Science.gov (United States)

    Bar-Zion, Avinoam; Yin, Melissa; Adam, Dan; Foster, F Stuart

    2016-08-01

    Alterations in tumor perfusion and microenvironment have been shown to be associated with aggressive cancer phenotypes, raising the need for noninvasive methods of tracking these changes. Dynamic contrast-enhanced ultrasound (DCEUS) and photoacoustic (PA) imaging serve as promising candidates-one has the ability to measure tissue perfusion, whereas the other can be used to monitor tissue oxygenation and hemoglobin concentration. In this study, we investigated the relationship between the different functional parameters measured with DCEUS and PA imaging, using two morphologically different hind-limb tumor models and drug-induced alterations in an orthotopic breast tumor model. Imaging results showed some correlation between perfusion and oxygen saturation maps and the ability to sensitively monitor antivascular treatment. In addition, DCEUS measurements revealed different vascular densities in the core of specific tumors compared with their rims. Noncorrelated perfusion and hemoglobin concentration measurements facilitated discrimination between blood lakes and necrotic areas. Taken together, our results illustrate the utility of a combined contrast-enhanced ultrasound method with photoacoustic imaging to visualize blood flow patterns in tumors. Cancer Res; 76(15); 4320-31. ©2016 AACR. PMID:27325651

  17. Functional magnetic resonance imaging of the normal and abnormal visual system in early life

    DEFF Research Database (Denmark)

    Born, A.P.; Miranda Gimenez-Ricco, Maria Jo; Rostrup, Egill;

    2000-01-01

    stroboscopic light stimulation could be demonstrated in all technically acceptable data sets from children with a post-menstrual age (PMA) of > 41 weeks, but not in younger infants. Children < 60 weeks PMA showed either a blood oxygenation level-dependent (BOLD) signal increase or decrease, while all older...

  18. Gadolinium(III-DOTA Complex Functionalized with BODIPY as a Potential Bimodal Contrast Agent for MRI and Optical Imaging

    Directory of Open Access Journals (Sweden)

    Matthias Ceulemans

    2015-11-01

    Full Text Available The synthesis and characterization of a novel gadolinium(III DOTA complex functionalized with a boron-dipyrromethene derivative (BODIPY is described. The assembly of the complex relies on azide diazotransfer chemistry in a copper tube flow reactor. The azide thus formed is coupled directly with an alkyne via click chemistry, resulting into a paramagnetic and luminescent gadolinium(III complex. Luminescent data and relaxometric properties of the complex have been evaluated, suggesting the potential applicability of the complexes as a bimodal contrast agent for magnetic resonance and optical imaging. The complex displays a bright emission at 523 nm with an absorption maximum of 507 nm and high quantum yields of up to 83% in water. The proton relaxivity of the complex measured at 310 K and at frequencies of 20 and 60 MHz had the values of 3.9 and 3.6 s−1·mM−1, respectively.

  19. Estimates of the Planet Yield from Ground-based High-contrast Imaging Observations as a Function of Stellar Mass

    Science.gov (United States)

    Crepp, Justin R.; Johnson, John Asher

    2011-06-01

    We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into consideration the important factors that govern the likelihood for imaging a planet, including the statistical properties of stars in the solar neighborhood, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys, both biased and unbiased, and express the resulting planet yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date (i.e., HR 8799, β Pic). Using the most recent empirical findings for the occurrence rate of gas-giant planets from radial velocity (RV) surveys, our simulations indicate that naive extrapolation of the Doppler planet population to semimajor axes accessible to high-contrast instruments provides an excellent agreement between simulations and observations using present-day contrast levels. In addition to being intrinsically young and sufficiently bright to serve as their own beacon for adaptive optics correction, A-stars have a high planet occurrence rate and propensity to form massive planets in wide orbits, making them ideal targets. The same effects responsible for creating a multitude of detectable planets around massive stars conspire to reduce the number orbiting low-mass stars. However, in the case of a young stellar cluster, where targets are approximately the same age and situated at roughly the same distance, MK-stars can easily dominate the number of detections because of an observational bias related to small number statistics. The degree to which low-mass stars produce the most planet detections in this special case depends upon whether multiple

  20. BOLD signal and functional connectivity associated with loving kindness meditation.

    Science.gov (United States)

    Garrison, Kathleen A; Scheinost, Dustin; Constable, R Todd; Brewer, Judson A

    2014-05-01

    Loving kindness is a form of meditation involving directed well-wishing, typically supported by the silent repetition of phrases such as "may all beings be happy," to foster a feeling of selfless love. Here we used functional magnetic resonance imaging to assess the neural substrate of loving kindness meditation in experienced meditators and novices. We first assessed group differences in blood oxygen level-dependent (BOLD) signal during loving kindness meditation. We next used a relatively novel approach, the intrinsic connectivity distribution of functional connectivity, to identify regions that differ in intrinsic connectivity between groups, and then used a data-driven approach to seed-based connectivity analysis to identify which connections differ between groups. Our findings suggest group differences in brain regions involved in self-related processing and mind wandering, emotional processing, inner speech, and memory. Meditators showed overall reduced BOLD signal and intrinsic connectivity during loving kindness as compared to novices, more specifically in the posterior cingulate cortex/precuneus (PCC/PCu), a finding that is consistent with our prior work and other recent neuroimaging studies of meditation. Furthermore, meditators showed greater functional connectivity during loving kindness between the PCC/PCu and the left inferior frontal gyrus, whereas novices showed greater functional connectivity during loving kindness between the PCC/PCu and other cortical midline regions of the default mode network, the bilateral posterior insula lobe, and the bilateral parahippocampus/hippocampus. These novel findings suggest that loving kindness meditation involves a present-centered, selfless focus for meditators as compared to novices. PMID:24944863

  1. Skeletal muscle microvascular function in girls with Turner syndrome

    Science.gov (United States)

    West, Sarah L.; O'Gorman, Clodagh S.; Elzibak, Alyaa H.; Caterini, Jessica; Noseworthy, Michael D.; Rayner, Tammy; Hamilton, Jill; Wells, Greg D.

    2014-01-01

    Background Exercise intolerance is prevalent in individuals with Turner Syndrome (TS). We recently demonstrated that girls with TS have normal aerobic but altered skeletal muscle anaerobic metabolism compared to healthy controls (HC). The purpose of this study was to compare peripheral skeletal muscle microvascular function in girls with TS to HC after exercise. We hypothesized that girls with TS would have similar muscle blood-oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) signal responses during recovery from exercise compared to HC. Methods Thirteen TS participants and 8 HC completed testing. BOLD MRI was used to measure skeletal muscle microvascular response during 60 second recovery, following 60 s of exercise at 65% of maximal workload. Exercise and recovery were repeated four times, and the BOLD signal time course was fit to a four-parameter sigmoid function. Results Participants were 13.7 ± 3.1 years old and weighed 47.9 ± 14.6 kg. The mean change in BOLD signal intensity following exercise at the end of recovery, the mean response time of the function/the washout of deoxyhemoglobin, and the mean half-time of recovery were similar between the TS and HC groups. Conclusions Our results demonstrate that compared to HC, peripheral skeletal muscle microvascular function following exercise in girls with TS is not impaired. General significance This study supports the idea that the aerobic energy pathway is not impaired in children with TS in response to submaximal exercise. Other mechanisms are likely responsible for exercise intolerance in TS; this needs to be further investigated. PMID:26676172

  2. Application of 3DAC (3D anisotropy contrast) imaging to predict motor function outcome of patients with cerebral infarction

    International Nuclear Information System (INIS)

    ThreeDAC (3D anisotropy contrast) image can depict neuronal fibers in 3 dimensions and the way those anatomical structures exist. However, despite its sophistication, quantitative analysis of 3DAC image has been performed poorly, probably, due to difficulties collecting numerical factors, thus we have tried to evaluate a feasible quantitative 3DAC image technique to predict motor function outcome in patients with cerebral infarction. Twenty-five patients with a acute cerebral infarctions, who underwent 3DAC procedure with 3 tesla MRI within 1 week after the onset, were enrolled in this study. To assess motor function, we applied manual muscle testing (MMT) score, which was modified by designating from 1 to 13 points corresponding to MMT, during both the onset and 3 months later. 3DAC image was created through the procedure assigning each direction to red, green and blue (RGB) colors after obtaining rare 3DAC images. On the slice showing the maximally injured region, Injured Fiber Ratio (IFR), defined as the ratio of injured area on horizontal fibers shown as blue area to the area of whole horizontal fibers in a healthy side, was calculated and compared with MMT score. Although MMT score at the onset did not correlate significantly with IFR, each MMT score of the arm and leg 3 months later revealed a significant correlation with IFR(R2=0.47 and R2=0.67, respectively). Given these results, by exploiting the IFR obtained from 3DAC image a motor function outcome in patients with cerebral infarction might be predicted even in a very acute stage and 3DAC image could be a feasible modality for analyzing a neuronal injury in cerebral infarction patients. (author)

  3. Interictal functional connectivity of human epileptic networks assessed by intracerebral EEG and BOLD signal fluctuations.

    Directory of Open Access Journals (Sweden)

    Gaelle Bettus

    Full Text Available In this study, we aimed to demonstrate whether spontaneous fluctuations in the blood oxygen level dependent (BOLD signal derived from resting state functional magnetic resonance imaging (fMRI reflect spontaneous neuronal activity in pathological brain regions as well as in regions spared by epileptiform discharges. This is a crucial issue as coherent fluctuations of fMRI signals between remote brain areas are now widely used to define functional connectivity in physiology and in pathophysiology. We quantified functional connectivity using non-linear measures of cross-correlation between signals obtained from intracerebral EEG (iEEG and resting-state functional MRI (fMRI in 5 patients suffering from intractable temporal lobe epilepsy (TLE. Functional connectivity was quantified with both modalities in areas exhibiting different electrophysiological states (epileptic and non affected regions during the interictal period. Functional connectivity as measured from the iEEG signal was higher in regions affected by electrical epileptiform abnormalities relative to non-affected areas, whereas an opposite pattern was found for functional connectivity measured from the BOLD signal. Significant negative correlations were found between the functional connectivities of iEEG and BOLD signal when considering all pairs of signals (theta, alpha, beta and broadband and when considering pairs of signals in regions spared by epileptiform discharges (in broadband signal. This suggests differential effects of epileptic phenomena on electrophysiological and hemodynamic signals and/or an alteration of the neurovascular coupling secondary to pathological plasticity in TLE even in regions spared by epileptiform discharges. In addition, indices of directionality calculated from both modalities were consistent showing that the epileptogenic regions exert a significant influence onto the non epileptic areas during the interictal period. This study shows that functional

  4. Work function contrast and energy band modulation between amorphous and crystalline Ge2Sb2Te5 films

    Science.gov (United States)

    Tong, H.; Yang, Z.; Yu, N. N.; Zhou, L. J.; Miao, X. S.

    2015-08-01

    The work function (WF) is of crucial importance to dominate the carrier transport properties of the Ge-Sb-Te based interfaces. In this letter, the electrostatic force microscopy is proposed to extract the WF of Ge2Sb2Te5 (GST) films with high spatial and energy resolution. The measured WF of as-deposited amorphous GST is 5.34 eV and decreases drastically after the amorphous GST is crystallized by annealing or laser illumination. A 512 × 512 array 2D-WF map is designed to study the WF spatial distribution and shows a good consistency. The WF contrast between a-GST and c-GST is ascribed to band modulation, especially the modification of electron affinity including the contribution of charges or dipoles. Then, the band alignments of GST/n-Si heterostructures are obtained based on the Anderson's rule. Due to the band modulation, the I-V characteristics of a-GST/Si heterojunction and c-GST/Si heterojunction are very different from each other. The quantitative relationship is calculated by solving the Poisson's equation, which agrees well with the I-V measurements. Our findings not only suggest a way to further understand the electrical transport properties of Ge-Sb-Te based interfaces but also provide a non-touch method to distinguish crystalline area from amorphous matrix with high spatial resolution.

  5. Work function contrast and energy band modulation between amorphous and crystalline Ge2Sb2Te5 films

    International Nuclear Information System (INIS)

    The work function (WF) is of crucial importance to dominate the carrier transport properties of the Ge-Sb-Te based interfaces. In this letter, the electrostatic force microscopy is proposed to extract the WF of Ge2Sb2Te5 (GST) films with high spatial and energy resolution. The measured WF of as-deposited amorphous GST is 5.34 eV and decreases drastically after the amorphous GST is crystallized by annealing or laser illumination. A 512 × 512 array 2D-WF map is designed to study the WF spatial distribution and shows a good consistency. The WF contrast between a-GST and c-GST is ascribed to band modulation, especially the modification of electron affinity including the contribution of charges or dipoles. Then, the band alignments of GST/n-Si heterostructures are obtained based on the Anderson's rule. Due to the band modulation, the I-V characteristics of a-GST/Si heterojunction and c-GST/Si heterojunction are very different from each other. The quantitative relationship is calculated by solving the Poisson's equation, which agrees well with the I-V measurements. Our findings not only suggest a way to further understand the electrical transport properties of Ge-Sb-Te based interfaces but also provide a non-touch method to distinguish crystalline area from amorphous matrix with high spatial resolution

  6. Contrast sensitivity function in stereoscopic viewing of Gabor patches on a medical polarized three-dimensional stereoscopic display

    Science.gov (United States)

    Rousson, Johanna; Haar, Jérémy; Santal, Sarah; Kumcu, Asli; Platiša, Ljiljana; Piepers, Bastian; Kimpe, Tom; Philips, Wilfried

    2016-03-01

    While three-dimensional (3-D) imaging systems are entering hospitals, no study to date has explored the luminance calibration needs of 3-D stereoscopic diagnostic displays and if they differ from two-dimensional (2-D) displays. Since medical display calibration incorporates the human contrast sensitivity function (CSF), we first assessed the 2-D CSF for benchmarking and then examined the impact of two image parameters on the 3-D stereoscopic CSF: (1) five depth plane (DP) positions (between DP: -171 and DP: 2853 mm), and (2) three 3-D inclinations (0 deg, 45 deg, and 60 deg around the horizontal axis of a DP). Stimuli were stereoscopic images of a vertically oriented 2-D Gabor patch at one of seven frequencies ranging from 0.4 to 10 cycles/deg. CSFs were measured for seven to nine human observers with a staircase procedure. The results indicate that the 2-D CSF model remains valid for a 3-D stereoscopic display regardless of the amount of disparity between the stereo images. We also found that the 3-D CSF at DP≠0 does not differ from the 3-D CSF at DP=0 for DPs and disparities which allow effortless binocular fusion. Therefore, the existing 2-D medical luminance calibration algorithm remains an appropriate tool for calibrating polarized stereoscopic medical displays.

  7. Spatial functional distribution in the corticospinal tract at the corona radiata. A three-dimensional anisotropy contrast study

    International Nuclear Information System (INIS)

    The spatial functional distribution of the nerve fibers was investigated in the corticospinal tract at the level of the corona radiata. Thirteen patients with corona radiata infarction underwent axial single-shot echo planar diffusion-weighted magnetic resonance imaging using a 1.5 Tesla scanner. Image analysis used the three-dimensional anisotropy contrast (3DAC) method to demarcate the nerve fibers in the corticospinal tract. Axial 3DAC images demonstrated the corticospinal tract as a distinct area indicating nerve fiber integrity in all normal hemispheres and infraction as a dark or black area in affected hemispheres. Seven patients with upper extremity-dominant motor dysfunction had infarction located in the middle one third of the corticospinal tract. A patient with lower extremity-dominant motor dysfunction had infarction in the posterior one third. Five patients with equal motor dysfunction in the upper and lower extremities had infarction in both the middle and posterior one thirds of the corticospinal tract. The recovery of motor dysfunction at one month follow up correlated with the location of the corticospinal; tract injury on the initial 3DAC images. The findings of the 3DAC images provide an indicator of the pattern and the recovery from acute and chronic motor dysfunction in patients with corona radiata infarction. (author)

  8. Feasibility of Using Limited-Population-Based Arterial Input Function for Pharmacokinetic Modeling of Osteosarcoma Dynamic Contrast-Enhanced MRI Data

    OpenAIRE

    Wang, YA; Huang, Wei; Panicek, David M.; Schwartz, Lawrence H.; Koutcher, Jason A

    2008-01-01

    For clinical dynamic contrast-enhanced (DCE) MRI studies, it is often not possible to obtain reliable arterial input function (AIF) in each measurement. Thus, it is important to find a representative AIF for pharmacokinetic modeling of DCE-MRI data when individual AIF (Ind-AIF) measurements are not available. A total of 16 patients with osteosarcomas in the lower extremity (knee region) underwent multislice DCE-MRI. Reliable Ind-AIFs were obtained in five patients with a contrast injection ra...

  9. The Psychoactive Designer Drug and Bath Salt Constituent MDPV Causes Widespread Disruption of Brain Functional Connectivity.

    Science.gov (United States)

    Colon-Perez, Luis M; Tran, Kelvin; Thompson, Khalil; Pace, Michael C; Blum, Kenneth; Goldberger, Bruce A; Gold, Mark S; Bruijnzeel, Adriaan W; Setlow, Barry; Febo, Marcelo

    2016-08-01

    The abuse of 'bath salts' has raised concerns because of their adverse effects, which include delirium, violent behavior, and suicide ideation in severe cases. The bath salt constituent 3,4-methylenedioxypyrovalerone (MDPV) has been closely linked to these and other adverse effects. The abnormal behavioral pattern produced by acute high-dose MDPV intake suggests possible disruptions of neural communication between brain regions. Therefore, we determined if MDPV exerts disruptive effects on brain functional connectivity, particularly in areas of the prefrontal cortex. Male rats were imaged following administration of a single dose of MDPV (0.3, 1.0, or 3.0 mg/kg) or saline. Resting state brain blood oxygenation level-dependent (BOLD) images were acquired at 4.7 T. To determine the role of dopamine transmission in MDPV-induced changes in functional connectivity, a group of rats received the dopamine D1/D2 receptor antagonist cis-flupenthixol (0.5 mg/kg) 30 min before MDPV. MDPV dose-dependently reduced functional connectivity. Detailed analysis of its effects revealed that connectivity between frontal cortical and striatal areas was reduced. This included connectivity between the prelimbic prefrontal cortex and other areas of the frontal cortex and the insular cortex with hypothalamic, ventral, and dorsal striatal areas. Although the reduced connectivity appeared widespread, connectivity between these regions and somatosensory cortex was not as severely affected. Dopamine receptor blockade did not prevent the MDPV-induced decrease in functional connectivity. The results provide a novel signature of MDPV's in vivo mechanism of action. Reduced brain functional connectivity has been reported in patients suffering from psychosis and has been linked to cognitive dysfunction, audiovisual hallucinations, and negative affective states akin to those reported for MDPV-induced intoxication. The present results suggest that disruption of functional connectivity networks

  10. Structural connectivity in schizophrenia and its impact on the dynamics of spontaneous functional networks

    Science.gov (United States)

    Cabral, Joana; Fernandes, Henrique M.; Van Hartevelt, Tim J.; James, Anthony C.; Kringelbach, Morten L.; Deco, Gustavo

    2013-12-01

    The neuropathology of schizophrenia remains unclear. Some insight has come from modern neuroimaging techniques, which offer an unparalleled opportunity to explore in vivo the structure and function of the brain. Using functional magnetic resonance imaging, it has been found that the large-scale resting-state functional connectivity (rsFC) in schizophrenia — measured as the temporal correlations of the blood-oxygen-level-dependent (BOLD) signal — exhibit altered network topology, with lower small-world index. The origin of these rsFC alterations and link with the underlying structural connectivity remain unclear. In this work, we used a computational model of spontaneous large-scale brain activity to explore the role of the structural connectivity in the large-scale dynamics of the brain in health and schizophrenia. The structural connectomes from 15 adolescent patients with early-onset schizophrenia and 15 age- and gender-matched controls were built from diffusion tensor imaging data to detect the white matter tracts between 90 brain areas. Brain areas, simulated using a reduced dynamic mean-field model, receive excitatory input from other areas in proportion to the number of fibre tracts between them. The simulated mean field activity was transformed into BOLD signal, and the properties of the simulated functional networks were analyzed. Our results suggest that the functional alterations observed in schizophrenia are not directly linked to alterations in the structural topology. Instead, subtly randomized and less small-world functional networks appear when the brain operates with lower global coupling, which shifts the dynamics from the optimal healthy regime.

  11. Structural connectivity in schizophrenia and its impact on the dynamics of spontaneous functional networks

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Joana [Theoretical and Computational Neuroscience Group, Center of Brain and Cognition, Universitat Pompeu Fabra, Barcelona 08018 (Spain); Department of Psychiatry, University of Oxford, Oxford OX3 7JX (United Kingdom); Fernandes, Henrique M.; Van Hartevelt, Tim J.; Kringelbach, Morten L. [Department of Psychiatry, University of Oxford, Oxford OX3 7JX (United Kingdom); Center of Functionally Integrative Neuroscience (CFIN), Aarhus University, Aarhus (Denmark); James, Anthony C. [Department of Psychiatry, University of Oxford, Oxford OX3 7JX (United Kingdom); Highfield Unit, Warneford Hospital, Oxford OX3 7JX (United Kingdom); Deco, Gustavo [Theoretical and Computational Neuroscience Group, Center of Brain and Cognition, Universitat Pompeu Fabra, Barcelona 08018 (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010 (Spain)

    2013-12-15

    The neuropathology of schizophrenia remains unclear. Some insight has come from modern neuroimaging techniques, which offer an unparalleled opportunity to explore in vivo the structure and function of the brain. Using functional magnetic resonance imaging, it has been found that the large-scale resting-state functional connectivity (rsFC) in schizophrenia — measured as the temporal correlations of the blood-oxygen-level-dependent (BOLD) signal — exhibit altered network topology, with lower small-world index. The origin of these rsFC alterations and link with the underlying structural connectivity remain unclear. In this work, we used a computational model of spontaneous large-scale brain activity to explore the role of the structural connectivity in the large-scale dynamics of the brain in health and schizophrenia. The structural connectomes from 15 adolescent patients with early-onset schizophrenia and 15 age- and gender-matched controls were built from diffusion tensor imaging data to detect the white matter tracts between 90 brain areas. Brain areas, simulated using a reduced dynamic mean-field model, receive excitatory input from other areas in proportion to the number of fibre tracts between them. The simulated mean field activity was transformed into BOLD signal, and the properties of the simulated functional networks were analyzed. Our results suggest that the functional alterations observed in schizophrenia are not directly linked to alterations in the structural topology. Instead, subtly randomized and less small-world functional networks appear when the brain operates with lower global coupling, which shifts the dynamics from the optimal healthy regime.

  12. Functional MRI evidence for the decline of word retrieval and generation during normal aging.

    Science.gov (United States)

    Baciu, M; Boudiaf, N; Cousin, E; Perrone-Bertolotti, M; Pichat, C; Fournet, N; Chainay, H; Lamalle, L; Krainik, A

    2016-02-01

    This fMRI study aimed to explore the effect of normal aging on word retrieval and generation. The question addressed is whether lexical production decline is determined by a direct mechanism, which concerns the language operations or is rather indirectly induced by a decline of executive functions. Indeed, the main hypothesis was that normal aging does not induce loss of lexical knowledge, but there is only a general slowdown in retrieval mechanisms involved in lexical processing, due to possible decline of the executive functions. We used three tasks (verbal fluency, object naming, and semantic categorization). Two groups of participants were tested (Young, Y and Aged, A), without cognitive and psychiatric impairment and showing similar levels of vocabulary. Neuropsychological testing revealed that older participants had lower executive function scores, longer processing speeds, and tended to have lower verbal fluency scores. Additionally, older participants showed higher scores for verbal automatisms and overlearned information. In terms of behavioral data, older participants performed as accurate as younger adults, but they were significantly slower for the semantic categorization and were less fluent for verbal fluency task. Functional MRI analyses suggested that older adults did not simply activate fewer brain regions involved in word production, but they actually showed an atypical pattern of activation. Significant correlations between the BOLD (Blood Oxygen Level Dependent) signal of aging-related (A > Y) regions and cognitive scores suggested that this atypical pattern of the activation may reveal several compensatory mechanisms (a) to overcome the slowdown in retrieval, due to the decline of executive functions and processing speed and (b) to inhibit verbal automatic processes. The BOLD signal measured in some other aging-dependent regions did not correlate with the behavioral and neuropsychological scores, and the overactivation of these uncorrelated

  13. Structural connectivity in schizophrenia and its impact on the dynamics of spontaneous functional networks

    International Nuclear Information System (INIS)

    The neuropathology of schizophrenia remains unclear. Some insight has come from modern neuroimaging techniques, which offer an unparalleled opportunity to explore in vivo the structure and function of the brain. Using functional magnetic resonance imaging, it has been found that the large-scale resting-state functional connectivity (rsFC) in schizophrenia — measured as the temporal correlations of the blood-oxygen-level-dependent (BOLD) signal — exhibit altered network topology, with lower small-world index. The origin of these rsFC alterations and link with the underlying structural connectivity remain unclear. In this work, we used a computational model of spontaneous large-scale brain activity to explore the role of the structural connectivity in the large-scale dynamics of the brain in health and schizophrenia. The structural connectomes from 15 adolescent patients with early-onset schizophrenia and 15 age- and gender-matched controls were built from diffusion tensor imaging data to detect the white matter tracts between 90 brain areas. Brain areas, simulated using a reduced dynamic mean-field model, receive excitatory input from other areas in proportion to the number of fibre tracts between them. The simulated mean field activity was transformed into BOLD signal, and the properties of the simulated functional networks were analyzed. Our results suggest that the functional alterations observed in schizophrenia are not directly linked to alterations in the structural topology. Instead, subtly randomized and less small-world functional networks appear when the brain operates with lower global coupling, which shifts the dynamics from the optimal healthy regime

  14. Functional MRI study of cerebral cortical activation during volitional swallowing

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the somatotropic distribution and lateralization of motor and sensory cortical activity during swallowing in healthy adult human subjects using functional MR imaging. Nine healthy right-handed adult volunteers (6 men, 3 women; ages 22-38) were examined. Their cortical activities were evoked by having them swallow, five times, a small bolus of water (3 ml) supplied through a plastic catheter. As a positive control, the subjects performed five repetitions of right-handed grasping tasks. Blood oxygenation level-dependent images were obtained using a 1.5 Tesla MR system (Magnetom Vision, Siemens Germany; repetition time/echo time (TR/TE)=0.96/0.66, flip angle (FA)=90 deg). T1 weighted anatomical images were obtained for the same slices in each subject. Cerebral activity was observed most notably in the primary motor cortex and primary somatosensory cortex, followed by the premotor cortex, anterior cingulate cortex, frontal operculum, and insula. The hand-grasping task activated relatively superior parts of the primary motor and somatosensory cortices. The swallowing task, on the other hand, activated the inferior parts of the pre- and postcentral gyri. The hand-grasping activation of motor and sensory cortices was localized absolutely on the contralateral side, whereas swallowing activated the motor cortex either bilaterally or unilaterally. Swallowing activated the sensory cortex almost always bilaterally. This study suggested that fMRI could be used to identify the specific areas of cortical activation caused by various tasks, and to differentiate the locations of cortical activation between tasks. (author)

  15. Functional MRI study of cerebral cortical activation during volitional swallowing

    Energy Technology Data Exchange (ETDEWEB)

    Wakasa, Toru; Aiga, Hideki; Yanagi, Yoshinobu; Kawai, Noriko; Sugimoto, Tomosada; Kuboki, Takuo; Kishi, Kanji [Okayama Univ. (Japan). Graduate School of Medicine and Dentistry

    2002-12-01

    The purpose of this study was to investigate the somatotropic distribution and lateralization of motor and sensory cortical activity during swallowing in healthy adult human subjects using functional MR imaging. Nine healthy right-handed adult volunteers (6 men, 3 women; ages 22-38) were examined. Their cortical activities were evoked by having them swallow, five times, a small bolus of water (3 ml) supplied through a plastic catheter. As a positive control, the subjects performed five repetitions of right-handed grasping tasks. Blood oxygenation level-dependent images were obtained using a 1.5 Tesla MR system (Magnetom Vision, Siemens Germany; repetition time/echo time (TR/TE)=0.96/0.66, flip angle (FA)=90 deg). T1 weighted anatomical images were obtained for the same slices in each subject. Cerebral activity was observed most notably in the primary motor cortex and primary somatosensory cortex, followed by the premotor cortex, anterior cingulate cortex, frontal operculum, and insula. The hand-grasping task activated relatively superior parts of the primary motor and somatosensory cortices. The swallowing task, on the other hand, activated the inferior parts of the pre- and postcentral gyri. The hand-grasping activation of motor and sensory cortices was localized absolutely on the contralateral side, whereas swallowing activated the motor cortex either bilaterally or unilaterally. Swallowing activated the sensory cortex almost always bilaterally. This study suggested that fMRI could be used to identify the specific areas of cortical activation caused by various tasks, and to differentiate the locations of cortical activation between tasks. (author)

  16. Influence of dense-array EEG cap on fMRI signal.

    Science.gov (United States)

    Luo, Qingfei; Glover, Gary H

    2012-09-01

    Dense-array (>64 channel) electroencephalography (EEG) systems are increasingly being used in simultaneous EEG-functional magnetic resonance imaging (fMRI) studies. However, with increasing channel count, dense-array EEG caps can induce more severe signal dropout in the MRI images than conventional systems due to the radiofrequency shielding effect of the denser wire bundle. This study investigates the influence of a 256-channel EEG cap on MRI image quality and detection sensitivity of blood oxygen level dependent fMRI signal. A theoretical model is first established to describe the impact of the EEG cap on anatomic signal, noise, signal-to-noise ratio, and contrast-to-noise ratio of blood oxygen level dependent signal. Seven subjects were scanned to measure and compare the T(2)-weighted image quality and fMRI detection sensitivity with and without the EEG cap using an auditory/visual/sensorimotor task. The results show that the dense-array EEG cap can substantially reduce the anatomic signal in the brain areas (visual cortex) near the conducting wires (average percent decrease ≈ 38%). However, the image signal-to-noise ratio with and without the EEG cap was comparable (percent decrease EEG caps in simultaneous EEG-fMRI experiments. PMID:22161695

  17. Contrast Materials

    Science.gov (United States)

    ... adverse reaction, you should tell your doctor about: allergies to contrast materials, food, drugs, dyes, preservatives, or animals medications ... These include: previous adverse reactions to iodine-based contrast materials history of ... disease dehydration sickle cell anemia , polycythemia and ...

  18. Differential Resting-State Functional Connectivity of Striatal Subregions in Bipolar Depression and Hypomania.

    Science.gov (United States)

    Altinay, Murat I; Hulvershorn, Leslie A; Karne, Harish; Beall, Erik B; Anand, Amit

    2016-04-01

    Bipolar disorder (BP) is characterized by periods of depression (BPD) and (hypo)mania (BPM), but the underlying state-related brain circuit abnormalities are not fully understood. Striatal functional activation and connectivity abnormalities have been noted in BP, but consistent findings have not been reported. To further elucidate striatal abnormalities in different BP states, this study investigated differences in resting-state functional connectivity of six striatal subregions in BPD, BPM, and healthy control (HC) subjects. Ninety medication-free subjects (30 BPD, 30 BPM, and 30 HC), closely matched for age and gender, were scanned using 3T functional magnetic resonance imaging (fMRI) acquired at resting state. Correlations of low-frequency blood oxygen level dependent signal fluctuations for six previously described striatal subregions were used to obtain connectivity maps of each subregion. Using a factorial design, main effects for differences between groups were obtained and post hoc pairwise group comparisons performed. BPD showed increased connectivity of the dorsal caudal putamen with somatosensory areas such as the insula and temporal gyrus. BPM group showed unique increased connectivity between left dorsal caudate and midbrain regions, as well as increased connectivity between ventral striatum inferior and thalamus. In addition, both BPD and BPM exhibited widespread functional connectivity abnormalities between striatal subregions and frontal cortices, limbic regions, and midbrain structures. In summary, BPD exhibited connectivity abnormalities of associative and somatosensory subregions of the putamen, while BPM exhibited connectivity abnormalities of associative and limbic caudate. Most other striatal subregion connectivity abnormalities were common to both groups and may be trait related. PMID:26824737

  19. Physiological measurements using ultra-high field fMRI: a review

    International Nuclear Information System (INIS)

    Functional MRI (fMRI) has grown to be the neuroimaging technique of choice for investigating brain function. This topical review provides an outline of fMRI methods and applications, with a particular emphasis on the recent advances provided by ultra-high field (UHF) scanners to allow functional mapping with greater sensitivity and improved spatial specificity. A short outline of the origin of the blood oxygenation level dependent (BOLD) contrast is provided, followed by a review of BOLD fMRI methods based on gradient-echo (GE) and spin-echo (SE) contrast. Phase based fMRI measures, as well as perfusion contrast obtained with the technique of arterial spin labelling (ASL), are also discussed. An overview of 7 T based functional neuroimaging is provided, outlining the potential advances to be made and technical challenges to be addressed. (topical review)

  20. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging

    Directory of Open Access Journals (Sweden)

    J.P. Borges

    2016-01-01

    Full Text Available Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61 and healthy age-matched subjects (n=24. Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01. With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04. In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men.

  1. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging.

    Science.gov (United States)

    Borges, J P; Lopes, G O; Verri, V; Coelho, M P; Nascimento, P M C; Kopiler, D A; Tibirica, E

    2016-01-01

    Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; PAPU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men. PMID:27599202

  2. The Impact of Contrast Massage on the Dynamics of the Functional Characteristics of the Microvasculature in Late Reproductive Age Female Patients with Chronic Endometritis

    OpenAIRE

    Azha Kh. Gaidarova; Natal'ya V. Kotenko; Detelina B. Kul'chitskaya; Anna Yu. Sycheva; Larisa Yu. Tarasova

    2014-01-01

    The author explores the functional characteristics of the microvasculature in late reproductive age women diagnosed with chronic endometritis before and after a course of contrast massage. Based on laser Doppler flowmetry data, the author singles out three types of functional changes in the microvasculature which had a high coefficient of correlation with the results of Doppler velocimetry of uterine blood-flow and changed dynamically during the treatment. The author reveals the therapeutic e...

  3. Repeatability of Detecting Visual Cortex Activity in Functional Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Mahboubeh Ma'soumbeigi

    2012-03-01

    Full Text Available Introduction As functional magnetic resonance imaging (fMRI is too expensive and time consuming, its frequent implementation is difficult. The aim of this study is to evaluate repeatability of detecting visual cortex activity in fMRI. Materials and Methods In this study, 15 normal volunteers (10 female, 5 male; Mean age±SD: 24.7±3.8 years attended. Functional magnetic resonance images were obtained during a visual task of sine-wave with spatial frequency of 1.84 cpd and temporal frequency of 8 Hz in three scan runs. Two runs of functional images were provided consecutively in a session, and the third run was provided 1-6 weeks later. The activation map was created using the data obtained from the block-designed fMRI study. Voxels whose Z value was above a threshold of 2.3, at a significance level p=0.05, were considered activated. After image processing, the blood oxygen level dependent (BOLD signal changes and the number of activated voxels in response to visual stimuli were compared in different runs. Results The results of this study demonstrate no significant difference between the number of activated voxels and BOLD signal in first and second runs in one session (Paired t-test, p>0.05. Moreover, there is a considerable correlation between first and second scan runs (rsignal=0.74, p=0.006 and rvoxel=0.62, p=0.03, while the correlation between the runs in separate sessions is weak (rsignal=0.28, p=0.38 and rvoxel=0.32, p=0.31. Conclusion Since the repeatability of BOLD signal and number of activated voxels in one session is considerably better than that in the separate sessions, it is suggested that in fMRI visual studies that need repeated scanning, scans should be acquired during a single session.

  4. The extended functional neuroanatomy of emotional processing biases for masked faces in major depressive disorder.

    Directory of Open Access Journals (Sweden)

    Teresa A Victor

    Full Text Available BACKGROUND: Major depressive disorder (MDD is associated with a mood-congruent processing bias in the amygdala toward face stimuli portraying sad expressions that is evident even when such stimuli are presented below the level of conscious awareness. The extended functional anatomical network that maintains this response bias has not been established, however. AIMS: To identify neural network differences in the hemodynamic response to implicitly presented facial expressions between depressed and healthy control participants. METHOD: Unmedicated-depressed participants with MDD (n=22 and healthy controls (HC; n=25 underwent functional MRI as they viewed face stimuli showing sad, happy or neutral face expressions, presented using a backward masking design. The blood-oxygen-level dependent (BOLD signal was measured to identify regions where the hemodynamic response to the emotionally valenced stimuli differed between groups. RESULTS: The MDD subjects showed greater BOLD responses than the controls to masked-sad versus masked-happy faces in the hippocampus, amygdala and anterior inferotemporal cortex. While viewing both masked-sad and masked-happy faces relative to masked-neutral faces, the depressed subjects showed greater hemodynamic responses than the controls in a network that included the medial and orbital prefrontal cortices and anterior temporal cortex. CONCLUSIONS: Depressed and healthy participants showed distinct hemodynamic responses to masked-sad and masked-happy faces in neural circuits known to support the processing of emotionally valenced stimuli and to integrate the sensory and visceromotor aspects of emotional behavior. Altered function within these networks in MDD may establish and maintain illness-associated differences in the salience of sensory/social stimuli, such that attention is biased toward negative and away from positive stimuli.

  5. Graph-based network analysis of resting-state functional MRI

    Directory of Open Access Journals (Sweden)

    Jinhui Wang

    2010-06-01

    Full Text Available In the past decade, resting-state functional MRI (R-fMRI measures of brain activity have attracted considerable attention. Based on changes in the blood oxygen level-dependent signal, R-fMRI offers a novel way to assess the brain’s spontaneous or intrinsic (i.e., task-free activity with both high spatial and temporal resolutions. The properties of both the intra- and inter-regional connectivity of resting-state brain activity have been well documented, promoting our understanding of the brain as a complex network. Specifically, the topological organization of brain networks has been recently studied with graph theory. In this review, we will summarize the recent advances in graph-based brain network analyses of R-fMRI signals, both in typical and atypical populations. Application of these approaches to R-fMRI data has demonstrated non-trivial topological properties of functional networks in the human brain. Among these is the knowledge that the brain’s intrinsic activity is organized as a small-world, highly efficient network, with significant modularity and highly connected hub regions. These network properties have also been found to change throughout normal development, aging and in various pathological conditions. The literature reviewed here suggests that graph-based network analyses are capable of uncovering system-level changes associated with different processes in the resting brain, which could provide novel insights into the understanding of the underlying physiological mechanisms of brain function. We also highlight several potential research topics in the future.

  6. Alterations in functional connectivity of resting state networks during experimental endotoxemia - An exploratory study in healthy men.

    Science.gov (United States)

    Labrenz, Franziska; Wrede, Karsten; Forsting, Michael; Engler, Harald; Schedlowski, Manfred; Elsenbruch, Sigrid; Benson, Sven

    2016-05-01

    Systemic inflammation impairs mood and cognitive functions, and seems to be involved in the pathophysiology of psychiatric disorders. Functional magnetic resonance imaging (fMRI) studies revealed altered task-related blood-oxygen-level-dependent (BOLD) responses during experimental endotoxemia, but little is known about effects of systemic inflammation on resting-state activity of the brain. Thus, we conducted a randomized, placebo-controlled study in healthy men receiving an intravenous injection of either low-dose (0.4ng/kg) lipopolysaccharide (LPS) (N=20) or placebo (N=25). Resting state activity was measured at baseline and 3.5h post-injection. Based on a two (condition)×two (group) design, we used multi-subject independent component analysis (ICA) to decompose and estimate functional connectivity within resting-state networks (RSNs). Seed-based analyses were applied to investigate the effect of LPS on the functional coupling for a priori-defined regions-of-interest (ROIs). ICA analyses identified 13 out of 35 components displaying common RSNs. Seed based analysis revealed greater functional connectivity between the left thalamus and the cerebellum after LPS compared to placebo administration, while the functional coupling between seeds within the amygdala, insula, and cingulate cortex and various brain regions including parieto-frontal networks was significantly reduced. Within the LPS group, endotoxin-induced increases in Interleukin (IL)-6 were significantly associated with resting-state connectivity between the left thalamus and left precuneus as well as the right posterior cingulate cortex. In summary, this exploratory study provides first evidence that systemic inflammation affects the coupling and regulation of multiple networks within the human brain at rest. PMID:26597151

  7. Functional MRI during Hippocampal Deep Brain Stimulation in the Healthy Rat Brain.

    Directory of Open Access Journals (Sweden)

    Nathalie Van Den Berge

    Full Text Available Deep Brain Stimulation (DBS is a promising treatment for neurological and psychiatric disorders. The mechanism of action and the effects of electrical fields administered to the brain by means of an electrode remain to be elucidated. The effects of DBS have been investigated primarily by electrophysiological and neurochemical studies, which lack the ability to investigate DBS-related responses on a whole-brain scale. Visualization of whole-brain effects of DBS requires functional imaging techniques such as functional Magnetic Resonance Imaging (fMRI, which reflects changes in blood oxygen level dependent (BOLD responses throughout the entire brain volume. In order to visualize BOLD responses induced by DBS, we have developed an MRI-compatible electrode and an acquisition protocol to perform DBS during BOLD fMRI. In this study, we investigate whether DBS during fMRI is valuable to study local and whole-brain effects of hippocampal DBS and to investigate the changes induced by different stimulation intensities. Seven rats were stereotactically implanted with a custom-made MRI-compatible DBS-electrode in the right hippocampus. High frequency Poisson distributed stimulation was applied using a block-design paradigm. Data were processed by means of Independent Component Analysis. Clusters were considered significant when p-values were <0.05 after correction for multiple comparisons. Our data indicate that real-time hippocampal DBS evokes a bilateral BOLD response in hippocampal and other mesolimbic structures, depending on the applied stimulation intensity. We conclude that simultaneous DBS and fMRI can be used to detect local and whole-brain responses to circuit activation with different stimulation intensities, making this technique potentially powerful for exploration of cerebral changes in response to DBS for both preclinical and clinical DBS.

  8. Functional MRI study of the brain with malformations of cortical development

    International Nuclear Information System (INIS)

    Objective: To explore the patterns of motor and linguistic activation in cortical and its correlations with abnormal gray matter in patients with malformations of cortical development (MCD) and epilepsy. Methods: Seven MCD patients with epilepsy (2 patients with focal cortical dysplasia, 2 heterotopia, 2 schizencephaly, and 1 polymicrogyria) underwent blood-oxygen-level-dependent (BOLD) functional MRI (fMRI) in a 3 T MR scanner when practicing bilateral fingers tapping,toes twisting, verb generation, and picture naming.Functional images were post-processed by using SPM 5 software based on a general linear model (GLM) to generate activations above a uniform threshold with the cluster size (≥30 voxels, P<0.001 corrected). The activations were recognized and classified by two experienced neuroradiologists, and then compared with that in abnormal gray matter. Results: The clusters and intensities of motor activations were mainly located in the sensormotor cortex (SMC) and premotor area (PMA). In linguistic tasks, activations produced by verb generation were found in language-associated cortical regions and PMA with higher activation in Wernicke area, picture naming significantly in the visual cortex, and language in Broca area. Combination of the two linguistic tasks produced significant clusters and intensities in language cortex. For MCD patients with abnormal cortical abnormalities, motor and language task could produce neuronal activities within normal as well as abnormal cortex regions. In 6 patients who underwent respective surgery, epileptic seizures decreased significantly, and the follow-up images demonstrated no new neurological dysfunctions and cognitive impairments. Conclusions: fMRI can visualize neuronal activities in patients with MCD and epilepsy and demonstrate the motor and linguistic activations occurring in normal and abnormal gray matter. It should be cautious for surgery in patient with MCD and epilepsy. (authors)

  9. Real-time myocardial contrast echocardiography can predict functional recovery and left ventricular remodeling after revascularization in patients with ischemic heart disease

    Institute of Scientific and Technical Information of China (English)

    ZENG Xin; SHU Xian-hong; PAN Cui-zhen; LI Qing; GUO Shi-zun; LIU Shi-zhen; CHEN Hao-zhu

    2007-01-01

    Background Previous studies showed that preservation of microvascular integrity after myocardial ischemia was associated with myocardial viability. Real-time myocardial contrast echocardiography (RT-MCE) is a promising modality for non-invasive evaluation of microcirculation perfusion. Thus, it provides a unique tool to detect myocardial viability. We sought in this study to investigate the role of RT-MCE in predicting left ventricular (LV) functional recovery and remodeling after revascularization in patients with ischemic heart disease.Methods Thirty-one patients with ischemic heart disease and resting regional LV dysfunction were included. LV volume,global and regional function were evaluated by echocardiography before and 6-9 months after revascularization.RT-MCE was performed before revascularization using low mechanical index power modulation imaging. Myocardial contrast opacification of dysfunctional segments was scored on a 3-point scale and mean contrast score in dysfunctional segments was calculated. Patients were divided into 2 groups according to mean contrast score in dysfunctional segments: group A, patients with mean contrast score ≥0.5 (n=19); group B, patients with mean contrast score < 0.5(n=12).Results Wall motion improvement was found to be 94.5%, 45.5% and 16.1% respectively (P<0.01) in homogenous,patchy and absent contrast opacification segments. At baseline, there was no significant difference in LV volume and global function between the two groups. After revascularization, group B had significantly larger LV end-diastolic volume (LVEDV) and LV end-systolic volume (LVESV), lower LV ejection fraction (LVEF) and higher wall motion score index(WMSI) than those of group A (all P<0.05). Revascularization was followed by significant improvement of LV volume and recovery of global LV function in group A (all P<0.01); however, in group B, after revascularization, deterioration of LVEDV (P<0.05) was observed, moreover LVESV, WMSI and LVEF

  10. Contrastive Analysis of Reports on Anti-secession law in People' Daily and New York Times: the Functional Perspective

    Institute of Scientific and Technical Information of China (English)

    梁满玲

    2009-01-01

    rom the perspective of three metafunctions in systemic-functional grammar in the hope that this paper can be a further test for the applicability of systemic-functional grammar in the analysis of Chinese texts.

  11. A functional magnetic resonance imaging investigation of motor control in Gilles de la Tourette syndrome during imagined and executed movements.

    Science.gov (United States)

    Zapparoli, Laura; Porta, Mauro; Gandola, Martina; Invernizzi, Paola; Colajanni, Valeria; Servello, Domenico; Zerbi, Alberto; Banfi, Giuseppe; Paulesu, Eraldo

    2016-02-01

    The current study investigated the neural correlates of voluntary motor control in 24 adult Gilles de la Tourette (GTS) patients. We examined whether imagination and the execution of the same voluntary movement - finger oppositions with either hand - were associated with specific patterns of activation. We also explored whether these patterns correlated with the severity of the syndrome, as measured by the Yale Global Tic Severity Scale (YGTSS) for motor tics. The presence of brain morphometric abnormalities was also assessed using voxel-based morphometry. Crucial to our experiment was the manipulation of the presence of an explicit motor outflow in the tasks. We anticipated a reduction in the ticking manifestation during the explicit motor task and brain activation differences between GTS patients and 24 age/gender-matched normal controls. The anticipated differences were all evident in the form of hyperactivations in the GTS patients in the premotor and prefrontal areas for both motor tasks for both hands; however, the motor imagery hyperactivations also involved rostral pre-frontal and temporo-parietal regions of the right hemisphere. The blood oxygen level-dependent responses of the premotor cortices during the motor imagery task were significantly correlated with the YGTSS scores. In contrast, no significant brain morphometric differences were found. This study provides evidence of a different neurofunctional organisation of motor control between adult patients with GTS and healthy controls that is independent from the actual execution of motor acts. The presence of an explicit motor outflow in GTS mitigates the manifestation of tics and the need for compensatory brain activity in the brain regions showing task-dependent hyperactivations. PMID:26566185

  12. Phase contrast image synthesis

    DEFF Research Database (Denmark)

    Glückstad, J.

    1996-01-01

    A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....

  13. Phase contrast image synthesis

    DEFF Research Database (Denmark)

    Glückstad, J.

    A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase funct...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....

  14. Single breath-hold assessment of cardiac function using an accelerated 3D single breath-hold acquisition technique - comparison of an intravascular and extravascular contrast agent

    Directory of Open Access Journals (Sweden)

    Makowski Marcus R

    2012-07-01

    Full Text Available Abstract Background Cardiovascular magnetic resonance (CMR is the current gold standard for the assessment of left ventricular (LV function. Repeated breath-holds are needed for standard multi-slice 2D cine steady-state free precession sequences (M2D-SSFP. Accelerated single breath-hold techniques suffer from low contrast between blood pool and myocardium. In this study an intravascular contrast agent was prospectively compared to an extravascular contrast agent for the assessment of LV function using a single-breath-hold 3D-whole-heart cine SSFP sequence (3D-SSFP. Methods LV function was assessed in fourteen patients on a 1.5 T MR-scanner (Philips Healthcare using 32-channel coil technology. Patients were investigated twice using a 3D-SSFP sequence (acquisition time 18–25 s after Gadopentetate dimeglumine (GdD, day 1 and Gadofosveset trisodium (GdT, day 2 administration. Image acquisition was accelerated using sensitivity encoding in both phase encoding directions (4xSENSE. CNR and BMC were both measured between blood and myocardium. The CNR incorporated noise measurements, while the BMC represented the coeffiancy between the signal from blood and myocardium [1]. Contrast to noise ratio (CNR, blood to myocardium contrast (BMC, image quality, LV functional parameters and intra-/interobserver variability were compared. A M2D-SSFP sequence was used as a reference standard on both days. Results All 3D-SSFP sequences were successfully acquired within one breath-hold after GdD and GdT administration. CNR and BMC were significantly (p vs. 23.7 and regression analysis showed a stronger correlation to the reference standard (R2 = 0.92 vs. R2 = 0.71, compared to 3D-SSFP with GdD. Conclusions A single-breath-hold 3D-whole-heart cine SSFP sequence in combination with 32-channel technology and an intravascular contrast agent allows for the accurate and fast assessment of LV function. Trial registration The study was approved by the local

  15. Functional connectivity of the human rostral and caudal cingulate motor areas in the brain resting state at 3T

    Energy Technology Data Exchange (ETDEWEB)

    Habas, Christophe [CHNO des Quinze-Vingts, UPMC Paris 6, Service de NeuroImagerie, Paris (France)

    2010-01-15

    Three cingulate motor areas have been described in monkeys, the rostral, dorsal, and ventral cingulate motor areas, and would control limbic-related motor activity. However, little anatomical data are available in human about the functional networks these cingulate areas underlie. Therefore, networks anchored in the rostral and caudal cingulate motor areas (rCMA and cCMA, respectively) were studied in human using functional connectivity during the brain resting state. Since the rCMA and cCMA are located just under the pre-supplementary and supplementary motor areas (pre-SMA and SMA), the pre-SMA- and SMA-centered networks were also studied to ensure that these four circuits were correctly dissociated. Data from 14 right-handed healthy volunteers were acquired at rest and analyzed by region of interest (ROI)-based functional connectivity. The blood oxygenation level-dependent (BOLD) signal fluctuations of separate ROIs located in rCMA, cCMA, pre-SMA, and SMA were successively used to identify significant temporal correlations with BOLD signal fluctuations of other brain regions. Low-frequency BOLD signal of the CMA was correlated with signal fluctuations in the prefrontal, cingulate, insular, premotor, motor, medial and inferior parietal cortices, putamen and thalamus, and anticorrelated with the default-mode network. rCMA was more in relation with prefrontal, orbitofrontal, and language-associated cortices than cCMA more related to sensory cortex. These cingulate networks were very similar to the pre-SMA- and SMA-centered networks, although pre-SMA and SMA showed stronger correlation with the prefrontal and inferior parietal cortices and with the cerebellum and the superior parietal cortex, respectively. The human cingulate motor areas constitute an interface between sensorimotor, limbic and executive systems, sharing common cortical, striatal, and thalamic relays with the overlying premotor medial areas. (orig.)

  16. Local activity determines functional connectivity in the resting human brain: a simultaneous FDG-PET/fMRI study.

    Science.gov (United States)

    Riedl, Valentin; Bienkowska, Katarzyna; Strobel, Carola; Tahmasian, Masoud; Grimmer, Timo; Förster, Stefan; Friston, Karl J; Sorg, Christian; Drzezga, Alexander

    2014-04-30

    Over the last decade, synchronized resting-state fluctuations of blood oxygenation level-dependent (BOLD) signals between remote brain areas [so-called BOLD resting-state functional connectivity (rs-FC)] have gained enormous relevance in systems and clinical neuroscience. However, the neural underpinnings of rs-FC are still incompletely understood. Using simultaneous positron emission tomography/magnetic resonance imaging we here directly investigated the relationship between rs-FC and local neuronal activity in humans. Computational models suggest a mechanistic link between the dynamics of local neuronal activity and the functional coupling among distributed brain regions. Therefore, we hypothesized that the local activity (LA) of a region at rest determines its rs-FC. To test this hypothesis, we simultaneously measured both LA (glucose metabolism) and rs-FC (via synchronized BOLD fluctuations) during conditions of eyes closed or eyes open. During eyes open, LA increased in the visual system, and the salience network (i.e., cingulate and insular cortices) and the pattern of elevated LA coincided almost exactly with the spatial pattern of increased rs-FC. Specifically, the voxelwise regional profile of LA in these areas strongly correlated with the regional pattern of rs-FC among the same regions (e.g., LA in primary visual cortex accounts for ∼ 50%, and LA in anterior cingulate accounts for ∼ 20% of rs-FC with the visual system). These data provide the first direct evidence in humans that local neuronal activity determines BOLD FC at rest. Beyond its relevance for the neuronal basis of coherent BOLD signal fluctuations, our procedure may translate into clinical research particularly to investigate potentially aberrant links between local dynamics and remote functional coupling in patients with neuropsychiatric disorders. PMID:24790196

  17. A functional magnetic resonance imaging study of working memory in youth after sports-related concussion: is it still working?

    Science.gov (United States)

    Keightley, Michelle L; Saluja, Rajeet Singh; Chen, Jen-Kai; Gagnon, Isabelle; Leonard, Gabriel; Petrides, Michael; Ptito, Alain

    2014-03-01

    Abstract In children, the importance of detecting deficits after mild traumatic brain injury (mTBI) or concussion has grown with the increasing popularity of leisure physical activities and contact sports. Whereas most postconcussive symptoms (PCS) are similar for children and adults, the breadth of consequences to children remains largely unknown. To investigate the effect of mTBI on brain function, we compared working memory performance and related brain activity using blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in 15 concussed youths and 15 healthy age-matched control subjects. Neuropsychological tests, self-perceived PCS, and levels of anxiety and depression were also assessed. Our results showed that, behaviorally, concussed youths had significantly worse performances on the working memory tasks, as well as on the Rey figure delayed recall and verbal fluency. fMRI results revealed that, compared to healthy children, concussed youths had significantly reduced task-related activity in bilateral dorsolateral prefrontal cortex, left premotor cortex, supplementary motor area, and left superior parietal lobule during performance of verbal and nonverbal working memory tasks. Additionally, concussed youths also showed less activation than healthy controls in the dorsal anterior cingulate cortex, left thalamus, and left caudate nucleus during the nonverbal task. Regression analysis indicated that BOLD signal changes in bilateral dorsolateral prefrontal cortex were significantly correlated with performance such that greater activities in these regions, relative to the control condition, were associated with greater accuracy. Our findings confirmed functional alterations in brain activity after concussion in youths, a result similar to that observed in adults. However, significant differences were noted. In particular, the observation of reduced working memory accuracy suggests that youths may be unable to engage compensatory

  18. Functional connectivity of the human rostral and caudal cingulate motor areas in the brain resting state at 3T

    International Nuclear Information System (INIS)

    Three cingulate motor areas have been described in monkeys, the rostral, dorsal, and ventral cingulate motor areas, and would control limbic-related motor activity. However, little anatomical data are available in human about the functional networks these cingulate areas underlie. Therefore, networks anchored in the rostral and caudal cingulate motor areas (rCMA and cCMA, respectively) were studied in human using functional connectivity during the brain resting state. Since the rCMA and cCMA are located just under the pre-supplementary and supplementary motor areas (pre-SMA and SMA), the pre-SMA- and SMA-centered networks were also studied to ensure that these four circuits were correctly dissociated. Data from 14 right-handed healthy volunteers were acquired at rest and analyzed by region of interest (ROI)-based functional connectivity. The blood oxygenation level-dependent (BOLD) signal fluctuations of separate ROIs located in rCMA, cCMA, pre-SMA, and SMA were successively used to identify significant temporal correlations with BOLD signal fluctuations of other brain regions. Low-frequency BOLD signal of the CMA was correlated with signal fluctuations in the prefrontal, cingulate, insular, premotor, motor, medial and inferior parietal cortices, putamen and thalamus, and anticorrelated with the default-mode network. rCMA was more in relation with prefrontal, orbitofrontal, and language-associated cortices than cCMA more related to sensory cortex. These cingulate networks were very similar to the pre-SMA- and SMA-centered networks, although pre-SMA and SMA showed stronger correlation with the prefrontal and inferior parietal cortices and with the cerebellum and the superior parietal cortex, respectively. The human cingulate motor areas constitute an interface between sensorimotor, limbic and executive systems, sharing common cortical, striatal, and thalamic relays with the overlying premotor medial areas. (orig.)

  19. Regional homogeneity analysis on acupoint specificity with resting-state functional magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    REN Xiu-jun; CHEN Hong-yan; WANG Bao-guo; ZHAO Bai-xiao; LI Shao-wu; ZHANG Lei; DAI Jian-ping; LIU Xiao-yuan; LUO Fang

    2012-01-01

    Background The mechanism of acupuncture analgesia in craniotomy has been widely studied.However,the theoretical basis for selection of acupoints has not been examined.In this study,we used the regional homogeneity method blood oxygen level-dependent (BOLD) signals to determine changes in brain activity in response to transcutaneous electrical stimulation on acupoints and non-acupoints in resting state functional magnetic resonance imaging (fMRI).Methods Twelve healthy volunteers were enrolled in this study.BOLD fMRI scanning of the brain was performed for 306 seconds before and 30 minutes after transcutaneous electrical stimulation on acupoints UB63 (Jinmen),LV3 (Tai chong),ST36 (Zusanli),and GB40 (Qiuxu).The procedure was repeated after one week with stimulation on non-acupoints (one was 9 above BL67,the second was 12 above BL67 (Kunlun),the third was 7 above Kl3,and the fourth was 10 above Kl3 (Taixi)).Results The regional homogeneity in the acupoint group was increased in the left thalamus,caudate,putamen,lentiform nucleus (BA19,30,39),postcentral gyrus,precentral gyrus (BA3,4,30,32),calcarine fissure,middle temporal gyrus (BA30),right superior temporal gyrus,inferior temporal gyrus (BA38),cuneus,and precuneus (BA7,19) when compared to the non-acupoint group.The regional homogeneity of the acupoint group was decreased in the left cerebellum posterior lobe,middle frontal gyrus (BA10),double-side precuneus (BA7),and the postcentral gyrus (BA40).Conclusions The brain region activated following acupoint stimulation is the ipsilateral pain-related brain region,which may relate to the therapeutic effect of acupuncture on pain relief.Further acupoint stimulation causes different central nervous responses compared to non-acupoint stimulation.

  20. Assessment of language lateralization with functional magnetic resonance imaging (fMRI)

    International Nuclear Information System (INIS)

    fMRI offers powerful methods to delineate which brain regions are engaged in language processing in the intact brain. Until now hemisphere dominance for language has been usually assessed by means of the intraoperative methods: the Wada test or electrocortical stimulation mapping. Recently functional MRI becomes the valuable method in determining hemisphere dominance for language. fMRI study was proved to be concordant with invasive measures. fMRI was carried out in 30 healthy selected participants (15 females: 10 strongly right-handed and 5 strongly left-handed; 15 males: 10 strongly right-handed and 5 strongly left-handed). The subject's handedness was assessed by standardized psychological tests inter alia the 'lateralization inventory'. Two different language tasks were used: a verb generation task and a phonological task. Subjects were scanned,while performing experimental block. The block contained alternately 8 active (language task) and 8 control conditions. Statistical analysis of evoked blood oxygenation level-dependent BOLD) responses, measured with echo planar imagining (1.5 T) were used. During a verb generation task in strongly right or left handed subjects the inferior frontal region was activated on the side opposite to the subject's handedness determined by the psychological test. Our fMRI studies demonstrated no gender effects on brain during these language tasks. Our study suggests that fMRI is a good device for the study of the language organization. The advantage of fMRI is its capacity for exact localization of activated areas. fMRI together with adequate neurolinguistic test could be promising routine preoperative tool in identification hemisphere dominance for language. These results encourage to further investigation for evaluating correlation in patients with brain injuries. (author)

  1. Visual cortex reactivity in sedated children examined with perfusion MRI (FAIR)

    DEFF Research Database (Denmark)

    Born, A P; Rostrup, E; Miranda, M J;

    2002-01-01

    Sleeping and sedated children can respond to visual stimulation with a decrease in blood oxygenation level dependent (BOLD) functional MRI signal response. The contribution of metabolic and hemodynamic parameters to this inverse signal response is incompletely understood. It has been hypothesized...... explanation for the negative BOLD response. Future studies will have to address if this response pattern is a consequence of age or sleep/sedation......Sleeping and sedated children can respond to visual stimulation with a decrease in blood oxygenation level dependent (BOLD) functional MRI signal response. The contribution of metabolic and hemodynamic parameters to this inverse signal response is incompletely understood. It has been hypothesized...

  2. Shape-based motion correction in dynamic contrast-enhanced MRI for quantitative assessment of renal function

    OpenAIRE

    Liu, W.; Sung, K.(Northwestern University, Evanston, USA); Ruan, D

    2014-01-01

    © 2014 American Association of Physicists in Medicine. Purpose: To incorporate a newly developed shape-based motion estimation scheme into magnetic resonance urography (MRU) and verify its efficacy in facilitating quantitative functional analysis. Methods: The authors propose a motion compensation scheme in MRU that consists of three sequential modules: MRU image acquisition, motion compensation, and quantitative functional analysis. They designed two sets of complementary experiments to eval...

  3. Increased sensitivity of fast BOLD fMRI with a subject-specific hemodynamic response function and application to epilepsy.

    Science.gov (United States)

    Proulx, Sébastien; Safi-Harb, Mouna; Levan, Pierre; An, Dongmei; Watanabe, Satsuki; Gotman, Jean

    2014-06-01

    Activation detection in functional Magnetic Resonance Imaging (fMRI) typically assumes the hemodynamic response to neuronal activity to be invariant across brain regions and subjects. Reports of substantial variability of the morphology of blood-oxygenation-level-dependent (BOLD) responses are accumulating, suggesting that the use of a single generic model of the expected response in general linear model (GLM) analyses does not provide optimal sensitivity due to model misspecification. Relaxing assumptions of the model can limit the impact of hemodynamic response function (HRF) variability, but at a cost on model parsimony. Alternatively, better specification of the model could be obtained from a priori knowledge of the HRF of a given subject, but the effectiveness of this approach has only been tested on simulation data. Using fast BOLD fMRI, we characterized the variability of hemodynamic responses to a simple event-related auditory-motor task, as well as its effect on activation detection with GLM analyses. We show the variability to be higher between subjects than between regions and variation in different regions to correlate from one subject to the other. Accounting for subject-related variability by deriving subject-specific models from responses to the task in some regions lead to more sensitive detection of responses in other regions. We applied the approach to epilepsy patients, where task-derived patient-specific models provided additional information compared to the use of a generic model for the detection of BOLD responses to epileptiform activity identified on scalp electro-encephalogram (EEG). This work highlights the importance of improving the accuracy of the model for detecting neuronal activation with fMRI, and the fact that it can be done at no cost to model parsimony through the acquisition of independent a priori information about the hemodynamic response. PMID:24582920

  4. Single session imaging of cerebellum at 7 Tesla: obtaining structure and function of multiple motor subsystems in individual subjects.

    Directory of Open Access Journals (Sweden)

    Melissa A Batson

    Full Text Available The recent increase in the use of high field MR systems is accompanied by a demand for acquisition techniques and coil systems that can take advantage of increased power and accuracy without being susceptible to increased noise. Physical location and anatomical complexity of targeted regions must be considered when attempting to image deeper structures with small nuclei and/or complex cytoarchitechtonics (i.e. small microvasculature and deep nuclei, such as the brainstem and the cerebellum (Cb. Once these obstacles are overcome, the concomitant increase in signal strength at higher field strength should allow for faster acquisition of MR images. Here we show that it is technically feasible to quickly and accurately detect blood oxygen level dependent (BOLD signal changes and obtain anatomical images of Cb at high spatial resolutions in individual subjects at 7 Tesla in a single one-hour session. Images were obtained using two high-density multi-element surface coils (32 channels in total placed beneath the head at the level of Cb, two channel transmission, and three-dimensional sensitivity encoded (3D, SENSE acquisitions to investigate sensorimotor activations in Cb. Two classic sensorimotor tasks were used to detect Cb activations. BOLD signal changes during motor activity resulted in concentrated clusters of activity within the Cb lobules associated with each task, observed consistently and independently in each subject: Oculomotor vermis (VI/VII and CrusI/II for pro- and anti-saccades; ipsilateral hemispheres IV-VI for finger tapping; and topographical separation of eye- and hand- activations in hemispheres VI and VIIb/VIII. Though fast temporal resolution was not attempted here, these functional patches of highly specific BOLD signal changes may reflect small-scale shunting of blood in the microvasculature of Cb. The observed improvements in acquisition time and signal detection are ideal for individualized investigations such as

  5. Measuring perfusion and bioenergetics simultaneously in mouse skeletal muscle: a multi-parametric functional-NMR approach

    International Nuclear Information System (INIS)

    A totally noninvasive set-up was developed for comprehensive NMR evaluation of mouse skeletal muscle function in vivo. Dynamic pulsed arterial spin labeling-NMRI perfusion and blood oxygenation level-dependent (BOLD) signal measurements were interleaved with 31P NMRS to measure both vascular response and oxidative capacities during stimulated exercise and subsequent recovery. Force output was recorded with a dedicated ergometer. Twelve exercise bouts were performed. The perfusion, BOLD signal, pH and force-time integral were obtained from mouse legs for each exercise. All reached a steady state after the second exercise, justifying the pointwise summation of the last 10 exercises to compensate for the limited 31P signal. In this way, a high temporal resolution of 2.5 s was achieved to provide a time constant for phosphocreatine (PCr) recovery (tPCr). The higher signal-to-noise ratio improved the precision of τ(PCr) measurement [coefficient of variation (CV)1/416.5% vs CV1/449.2% for a single exercise at a resolution of 30 s]. Inter-animal summation confirmed that τ(PCr) was stable at steady state, but shorter (89.3W8.6 s) than after the first exercise (148 s, p≤0.05). This novel experimental approach provides an assessment of muscle vascular response simultaneously to energetic function in vivo. Its pertinence was illustrated by observing the establishment of a metabolic steady state. This comprehensive tool offers new perspectives for the study of muscle pathology in mice models. (authors)

  6. Changes in Pain Processing in the Spinal Cord and Brainstem after Spinal Cord Injury Characterized by Functional Magnetic Resonance Imaging.

    Science.gov (United States)

    Stroman, Patrick W; Khan, Hamza S; Bosma, Rachel L; Cotoi, Andrea I; Leung, Roxanne; Cadotte, David W; Fehlings, Michael G

    2016-08-01

    Traumatic spinal cord injury (SCI) has a number of devastating consequences, including high prevalence of chronic pain and altered pain sensitivity. The causes of altered pain states vary depending on the injury and are difficult to diagnose and treat. A better understanding of pain mechanisms after SCI is expected to lead to better diagnostic capabilities and improved treatments. We therefore applied functional magnetic resonance imaging (fMRI) of the brainstem and spinal cord in a group of participants with previous traumatic SCI to characterize changes in pain processing as a result of their injuries. The same thermal stimulus was applied to the medial palm (C8 dermatome) as a series of repeated brief noxious thermal pulses in a group of 16 participants with a cervical (n = 14) and upper thoracic (n = 2) injuries. Functional MRI of the brainstem and spinal cord was used to determine the neuronal activity evoked by the noxious stimulation, and connectivity between regions was characterized with structural equation modeling (SEM). The results show that pain ratings, the location and magnitude of blood oxygenation-level dependent fMRI results, and connectivity assessed with SEM varied widely across participants. However, the results varied in relation to the perceived pain and the level/severity of injuries, particularly in terms of hypothalamus connectivity with other regions, and descending modulation via the periaqueductal gray matter-rostral ventromedial medulla-cord pathway. The results, therefore, appear to provide sensitive indicators of each individual's pain response, and information about the mechanisms of altered pain sensitivity. The ability to characterize changes in pain processing in individuals with SCI represents a significant technological advance. PMID:26801315

  7. Dialysis and contrast media

    International Nuclear Information System (INIS)

    In a previous survey we revealed uncertainty among responders about (a) whether or not to perform hemodialysis in patients with severely reduced renal function who had received contrast medium; and (b) when to perform hemodialysis in patients on regular treatment with hemodialysis or continuous ambulatory dialysis who received contrast medium. Therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and to issue guidelines. The committee performed a Medline search. Based on this, a report and guidelines were prepared. The report was discussed at the Ninth European Symposium on Urogenital Radiology in Genoa, Italy. Hemodialysis and peritoneal dialysis safely remove both iodinated and gadolinium-based contrast media. The effectiveness of hemodialysis depends on many factors including blood and dialysate flow rate, permeability of dialysis membrane, duration of hemodialysis and molecular size, protein binding, hydrophilicity, and electrical charge of the contrast medium. Generally, several hemodialysis sessions are needed to removal all contrast medium, whereas it takes 3 weeks for continuous ambulatory dialysis to remove the agent completely. There is no need to schedule the dialysis in relation to the injection of iodinated or MR contrast media or the injection of contrast agent in relation to the dialysis program. Hemodialysis does not protect poorly functioning kidneys against contrast-medium-induced nephrotoxicity. Simple guidelines are given. (orig.)

  8. Dialysis and contrast media

    Energy Technology Data Exchange (ETDEWEB)

    Morcos, Sameh K. [Department of Diagnostic Imaging, Northern General Hospital, Sheffield Teaching Hospitals NHS Trust, Sheffield S5 7AU (United Kingdom); Thomsen, Henrik S. [Department of Diagnostic Radiology 54E2, Copenhagen University Hospital at Herlev, Herlev Ringvej 75, 2730 Herlev (Denmark); Webb, Judith A.W. [Department of Diagnostic Imaging, St Bartholomew' s Hospital, London EC1A 7BE (United Kingdom)

    2002-12-01

    In a previous survey we revealed uncertainty among responders about (a) whether or not to perform hemodialysis in patients with severely reduced renal function who had received contrast medium; and (b) when to perform hemodialysis in patients on regular treatment with hemodialysis or continuous ambulatory dialysis who received contrast medium. Therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and to issue guidelines. The committee performed a Medline search. Based on this, a report and guidelines were prepared. The report was discussed at the Ninth European Symposium on Urogenital Radiology in Genoa, Italy. Hemodialysis and peritoneal dialysis safely remove both iodinated and gadolinium-based contrast media. The effectiveness of hemodialysis depends on many factors including blood and dialysate flow rate, permeability of dialysis membrane, duration of hemodialysis and molecular size, protein binding, hydrophilicity, and electrical charge of the contrast medium. Generally, several hemodialysis sessions are needed to removal all contrast medium, whereas it takes 3 weeks for continuous ambulatory dialysis to remove the agent completely. There is no need to schedule the dialysis in relation to the injection of iodinated or MR contrast media or the injection of contrast agent in relation to the dialysis program. Hemodialysis does not protect poorly functioning kidneys against contrast-medium-induced nephrotoxicity. Simple guidelines are given. (orig.)

  9. Functional magnetic resonance imaging of basal ganglia. Activation mapping with FLASH sequences for BOLD contrast and high resolution

    International Nuclear Information System (INIS)

    The activation pattern of putamen, internal and external division of globus pallidus was investigated during rapid pronation and supination of the right and left hand in 12 normal volunteers using a FLASH sequence with high resolution for functional magnetic resonance imaging (fMRI) at 1.5 T. The chosen paradigm for motor function led to a signal increase within the basal ganglia between 3 and 23%, depending on the structure and individual subject. In all cases significant activation could be found contralateral to the moving hand. In six cases activation was also found on the ipsilateral side. The activated areas within putamen, internal and external division of globus pallidus were less than 5 mm2. These first results indicate that fMRI studies of basal ganglia are feasible and might be suitable for analyzing basal ganglia disorders. (orig.)

  10. Using chemical and isotopic tracers to conceptualise hydrological function in a larger scale catchment draining contrasting geomorphic provinces

    Science.gov (United States)

    Capell, R.; Tetzlaff, D.; Soulsby, C.; Hartley, A. J.; Malcolm, I. A.

    2010-12-01

    A multivariate tracer study in the 749 km2 catchment of the North-Esk in north east Scotland was carried out to infer the dominant hydrological processes in two markedly different geomorphic provinces. The upper 60% of the catchment has montane headwaters dominated by impermeable metamorphic rocks, steep topography, peaty soils and a sub-arctic climate with over 1400mm of precipitation. The lowlands of the catchment are underlain by a major sandstone aquifer, and mainly have freely draining, fertile soils that support intensive arable farming under a drier climate with around 800mm of precipitation. Runoff in the uplands is dominated by near-surface processes with water of low alkalinity and low ionic strength. In contrast, tributaries in the lower parts of the catchment are characterised by alkaline waters with high concentrations of base cations and high levels of nitrate. Stable water isotope dynamics in precipitation and stream water were used to estimate mean transit times (MTT), indicating shorter MTTs in uplands with short turnover times especially in winter, while lowland stream MTTs are largely influenced by sandstone aquifer water and exceed several years. Multivariate statistical methods were used to derive a generic typology of catchment source waters, their spatial and temporal dynamics and particularly, how they integrate together at the larger catchment scale. The uplands dominate the winter high flow response of the whole catchment. The influence of lowland groundwater from major aquifers becomes more apparent under low flows. However, groundwater from small upland aquifers plays a critical ecosystem service in providing base flows which dilute pollutant inputs from lowland areas at the large catchment scale.

  11. Modeling of region-specific fMRI BOLD neurovascular response functions in rat brain reveals residual differences that correlate with the differences in regional evoked potentials.

    Science.gov (United States)

    Pawela, Christopher P; Hudetz, Anthony G; Ward, B Douglas; Schulte, Marie L; Li, Rupeng; Kao, Dennis S; Mauck, Matthew C; Cho, Younghoon R; Neitz, Jay; Hyde, James S

    2008-06-01

    The response of the rat visual system to flashes of blue light has been studied by blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI). The BOLD temporal response is dependent on the number of flashes presented and demonstrates a refractory period that depends on flash frequency. Activated brain regions included the primary and secondary visual cortex, superior colliculus (SC), dorsal lateral geniculate (DLG), and lateral posterior nucleus (LP), which were found to exhibit differing temporal responses. To explain these differences, the BOLD neurovascular response function was modeled. A second-order differential equation was developed and solved numerically to arrive at region-specific response functions. Included in the model are the light input from the diode (duty cycle), a refractory period, a transient response following onset and cessation of stimulus, and a slow adjustment to changes in the average level of the signal. Constants in the differential equation were evaluated for each region by fitting the model to the experimental BOLD response from a single flash, and the equation was then solved for multiple flashes. The simulation mimics the major features of the data; however, remaining differences in the frequency dependence of the response between the cortical and subcortical regions were unexplained. We hypothesized that these discrepancies were due to regional-specific differences in neuronal response to flash frequency. To test this hypothesis, cortical visual evoked potentials (VEPs) were recorded using the same stimulation protocol as the fMRI. Cortical VEPs were more suppressed than subcortical VEPs as flash frequency increased, supporting our hypothesis. This is the first report that regional differences in neuronal activation to the same stimulus lead to differential BOLD activation. PMID:18406628

  12. Complexity of spontaneous BOLD activity in default mode network is correlated with cognitive function in normal male elderly: a multiscale entropy analysis.

    Science.gov (United States)

    Yang, Albert C; Huang, Chu-Chung; Yeh, Heng-Liang; Liu, Mu-En; Hong, Chen-Jee; Tu, Pei-Chi; Chen, Jin-Fan; Huang, Norden E; Peng, Chung-Kang; Lin, Ching-Po; Tsai, Shih-Jen

    2013-02-01

    The nonlinear properties of spontaneous fluctuations in blood oxygen level-dependent (BOLD) signals remain unexplored. We test the hypothesis that complexity of BOLD activity is reduced with aging and is correlated with cognitive performance in the elderly. A total of 99 normal older and 56 younger male subjects were included. Cognitive function was assessed using Cognitive Abilities Screening Instrument and Wechsler Digit Span Task. We employed a complexity measure, multiscale entropy (MSE) analysis, and investigated appropriate parameters for MSE calculation from relatively short BOLD signals. We then compared the complexity of BOLD signals between the younger and older groups, and examined the correlation between cognitive test scores and complexity of BOLD signals in various brain regions. Compared with the younger group, older subjects had the most significant reductions in MSE of BOLD signals in posterior cingulate gyrus and hippocampal cortex. For older subjects, MSE of BOLD signals from default mode network areas, including hippocampal cortex, cingulate cortex, superior and middle frontal gyrus, and middle temporal gyrus, were found to be positively correlated with major cognitive functions, such as attention, orientation, short-term memory, mental manipulation, and language. MSE from subcortical regions, such as amygdala and putamen, were found to be positively correlated with abstract thinking and list-generating fluency, respectively. Our findings confirmed the hypothesis that complexity of BOLD activity was correlated with aging and cognitive performance based on MSE analysis, and may provide insights on how dynamics of spontaneous brain activity relates to aging and cognitive function in specific brain regions. PMID:22683008

  13. Mapping the effects of three dopamine agonists with different dyskinetogenic potential and receptor selectivity using pharmacological functional magnetic resonance imaging.

    Science.gov (United States)

    Delfino, Marina; Kalisch, Raffael; Czisch, Michael; Larramendy, Celia; Ricatti, Jimena; Taravini, Irene R E; Trenkwalder, Claudia; Murer, Mario Gustavo; Auer, Dorothee P; Gershanik, Oscar S

    2007-09-01

    The mechanisms underlying dopamine agonist-induced dyskinesia in Parkinson's disease remain poorly understood. Similar to patients, rats with severe nigrostriatal degeneration induced by 6-hydroxydopamine are more likely to show dyskinesia during chronic treatment with unselective dopamine receptor agonists than with D2 agonists, suggesting that D1 receptor stimulation alone or in conjunction with D2 receptor stimulation increases the chances of experiencing dyskinesia. As a first step towards disclosing drug-induced brain activation in dyskinesia, we examined the effects of dopamine agonists on behavior and blood oxygenation level-dependent (BOLD) signal in the striatum and motor cortex of rats with unilateral nigrostriatal lesions. Rats were rendered dyskinetic before pharmacologic functional magnetic resonance imaging by means of a repeated treatment regime with dopamine agonists. The unselective agonist apomorphine and the selective D1/D5 agonist SKF-81297 induced strong forelimb dyskinesia (FD) and axial dystonia and increased BOLD signal in the denervated striatum. Besides, SKF-81297 produced a significant but smaller BOLD increase in the intact striatum and a symmetric bilateral increase in the motor cortex. The D2 family agonist quinpirole, which induced mild dyskinesia on chronic treatment, did not produce BOLD changes in the striatum or motor cortex. Further evidence to support an association between BOLD changes and dyskinesia comes from a direct correlation between scores of FD and magnitude of drug-induced BOLD increases in the denervated striatum and motor cortex. Our results suggest that striatal and cortical activation induced by stimulation of D1/D5 receptors has a primary role in the induction of peak dose dyskinesia in parkinsonism. PMID:17287822

  14. Brain activation and hypothalamic functional connectivity during human non-rapid eye movement sleep: an EEG/fMRI study.

    Science.gov (United States)

    Kaufmann, C; Wehrle, R; Wetter, T C; Holsboer, F; Auer, D P; Pollmächer, T; Czisch, M

    2006-03-01

    Regional differences in sleep EEG dynamics indicate that sleep-related brain activity involves local brain processes with sleep stage specific activity patterns of neuronal populations. Macroscopically, it is not fully understood which cerebral brain regions are involved in the successive discontinuation of wakefulness. We simultaneously used EEG and functional MRI on 9 subjects (6 female: mean = 24.1 years, 3 male: mean = 26.0 years) and analyzed local blood oxygenation level dependent signal changes linked to the transition from wakefulness to different non-rapid eye movement (NREM) sleep stages (according to Rechtschaffen and Kales) of the first sleep cycles after 36 h of total sleep deprivation. Several brain regions throughout the cortex, the limbic lobe, the thalamus, the caudate nucleus, as well as midbrain structures, such as the mammillary body/hypothalamus, showed reduced activity during NREM sleep across all sleep stages. Additionally, we found deactivation patterns specific to NREM sleep stages compared with wakefulness suggesting that a synchronized sleeping state can be established only if these regions interact in a well-balanced way. Sleep stage 2, which is usually linked to the loss of self-conscious awareness, is associated with signal decreases comprising thalamic and hypothalamic regions, the cingulate cortex, the right insula and adjacent regions of the temporal lobe, the inferior parietal lobule and the inferior/middle frontal gyri. The hypothalamic region known to be of particular importance in the regulation of the sleep-wake cycle shows specific temporally correlated network activity with the cortex while the system is in the sleeping state, but not during wakefulness. We describe a specific pattern of decreased brain activity during sleep and suggest that this pattern must be synchronized for establishing and maintaining sleep. PMID:16339798

  15. Synaesthetic colour in the brain: beyond colour areas. A functional magnetic resonance imaging study of synaesthetes and matched controls.

    Directory of Open Access Journals (Sweden)

    Tessa M van Leeuwen

    Full Text Available BACKGROUND: In synaesthesia, sensations in a particular modality cause additional experiences in a second, unstimulated modality (e.g., letters elicit colour. Understanding how synaesthesia is mediated in the brain can help to understand normal processes of perceptual awareness and multisensory integration. In several neuroimaging studies, enhanced brain activity for grapheme-colour synaesthesia has been found in ventral-occipital areas that are also involved in real colour processing. Our question was whether the neural correlates of synaesthetically induced colour and real colour experience are truly shared. METHODOLOGY/PRINCIPAL FINDINGS: First, in a free viewing functional magnetic resonance imaging (fMRI experiment, we located main effects of synaesthesia in left superior parietal lobule and in colour related areas. In the left superior parietal lobe, individual differences between synaesthetes (projector-associator distinction also influenced brain activity, confirming the importance of the left superior parietal lobe for synaesthesia. Next, we applied a repetition suppression paradigm in fMRI, in which a decrease in the BOLD (blood-oxygenated-level-dependent response is generally observed for repeated stimuli. We hypothesized that synaesthetically induced colours would lead to a reduction in BOLD response for subsequently presented real colours, if the neural correlates were overlapping. We did find BOLD suppression effects induced by synaesthesia, but not within the colour areas. CONCLUSIONS/SIGNIFICANCE: Because synaesthetically induced colours were not able to suppress BOLD effects for real colour, we conclude that the neural correlates of synaesthetic colour experience and real colour experience are not fully shared. We propose that synaesthetic colour experiences are mediated by higher-order visual pathways that lie beyond the scope of classical, ventral-occipital visual areas. Feedback from these areas, in which the left parietal

  16. New MRI technologies. Diffusion MRI and its application to functional neuroimaging and analyses of white matter integrity

    International Nuclear Information System (INIS)

    Described is the technological aspect of MRI, MR diffusion-weighted imaging (MR-DWI), principles of its measurement and application for imaging the cerebral function and for aiding the quantitative diagnosis of brain diseases. The author explains the principle of MR imaging process; diffusion properties of water molecules, MR-DWI based on them and DW-fMRI of the brain; MR-diffusion tensor imaging (MR-DTI), its analysis and color acquisition, and tracking of white matter nerve fibers; analysis of white matter lesions by the tracking; and the new tracking method at the chiasm of nerve fascicles. The usual fMRI reflects the blood oxygen level depending (BOLD) signals whereas recently attracted DW-fMRI, the volume changes of nerve cells concomitant to nerve activation accompanying apparent changes of water diffusion coefficients in and out of cells which occur faster than BOLD signs, resulting in higher resolution of time and space. However, DWI requires the higher intensity of static magnetic field like 3T. MR-DTI acquires the anisotropic diffusion of water molecules using MR-DWI technique with application of 6 or more motion probing gradients, thus makes it possible to track the running directions of nerve fibers and capillary vessels, and is proposed to be a useful mean of specific fiber tracking in the white matter when displayed by 3 different colors exhibiting the directions like the right/left (x axis, red), anterior/posterior (y, green) and upper/lower (z, blue) sides of head. Recently, MR-DWI and MR-DTI have been found usable for pathogenic studies of brain diseases such as dementia. Tensor anisotropy is apparently lowered at the chiasm of nerve fascicles, the cause of tracking error, for which authors have developed a new method using the similarity of directional vector, not of tensor, before and behind the chiasm. As exemplified, MRI technology is further advancing even at present. (T.T.)

  17. Polytellurophenes provide imaging contrast towards unravelling the structure–property–function relationships in semiconductor:insulator polymer blends

    KAUST Repository

    Jahnke, Ashlee A.

    2015-02-27

    Polymer blends are broadly important in chemical science and chemical engineering and have led to a wide range of commercial products, however their precise structure and phase morphology is often not well understood. Here we show for the first time that π-conjugated polytellurophenes and high-density polyethylene form blends that can serve as active layers in field-effect transistor devices and can be characterized by a variety of element-specific imaging techniques such as STEM and EDX. Changing the hydrocarbon content and degree of branching on the polytellurophene side-chain leads to a variety of blend structures, and these variations can be readily visualized. Characterization by electron microscopy is complemented by topographic and X-ray methods to establish a nano- to micro-scale picture of these systems. We find that blends that possess microscale networks function best as electronic devices; however, contrary to previous notions a strong correlation between nanofiber formation and electrical performance is not observed. Our work demonstrates that use of organometallic polymers assists in clarifying relevant structure–property–function relationships in multicomponent systems such as semiconductor:insulator blends and sheds light on the structure development in polymer:polymer blends including crystallization, phase separation, and formation of supramolecular arrangements.

  18. Contrast lipocryolysis

    OpenAIRE

    Pinto, Hernán; Melamed, Graciela

    2014-01-01

    Alternative crystal structures are possible for all lipids and each different crystal structure is called a polymorphic form. Inter-conversion between polymorphisms would imply the possibility of leaning crystal formation toward the most effective polymorphism for adipocyte destruction. Food industry has been tempering lipids for decades. Tempering technology applied to lipocryolysis gave birth to “contrast lipocryolysis”, which involves pre- and post-lipocryolysis fat layer heating as part o...

  19. Microstructural Brain Differences Predict Functional Hemodynamic Responses in a Reward Processing Task

    OpenAIRE

    Càmara, E.; Rodríguez Fornells, Antoni; Münte, Thomas F.

    2010-01-01

    Many aspects of human behavior are driven by rewards, yet different people are differentially sensitive to rewards and punishment. In this study, we showthat white matter microstructure inthe uncinate/inferiorfronto-occipitalfasciculus, defined byfractional anisotropy values derived from diffusion tensor magnetic resonance images, correlates with both short-term (indexed by the fMRI blood oxygenation level-dependent response to reward in the nucleus accumbens) and long-term (indexed by the tr...

  20. Effects of viruses on bacterial functions under contrasting nutritional conditions for four species of bacteria isolated from Hong Kong waters

    Science.gov (United States)

    Liu, Hao; Yuan, Xiangcheng; Xu, Jie; Harrison, Paul J.; He, Lei; Yin, Kedong

    2015-09-01

    Free living viruses are ubiquitous in marine waters and concentrations are usually several times higher than the bacterial abundance. These viruses are capable of lysing host bacteria and therefore, play an important role in the microbial loop in oligotrophic waters. However, few studies have been conducted to compare the role of viruses in regulating bacterial abundance and heterotrophic activities between natural oligotrophic waters and anthropogenic influenced eutrophic waters. In this study, we examined viral effects on bacterial functions of four single bacterial species incubated with natural viral assemblages in seawater samples from eutrophic and oligotrophic waters. The viral-lysis of bacteria was significantly higher in eutrophic than oligotrophic waters. This suggests that viruses were capable of controlling bacterial abundance, respiration and production in the eutrophic waters. Cellular bacterial respiration and production was higher with viruses than without viruses, which was more evident in the oligotrophic waters. These results indicate that viruses can slow down bacterial consumption of oxygen and reduce bacteria-induced eutrophication effects in anthropogenic eutrophic waters, but switch to the role of sustaining the bacterial population when nutrients are limiting. There were bacterial species differences in resisting viral attack, which can influence the dominance and biodiversity of bacterial species in coastal waters.

  1. Central swallowing in normal adults using functional magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    Shasha Li; Cheng Luo; Chengqi He; Qiyong Gong; Dong Zhou

    2009-01-01

    BACKGROUND: While brain-imaging studies in healthy adults have indicated that multiple cortical regions are involved in swallowing, these functional imaging techniques have not been extensively applied to the complete understand neurophysiology of swallowing in China. A full understanding of normal swallowing neurophysiology is important for improving functional outcomes for dysphagia due to neurologic disorders or damage with increasing age. Thus the interpretations of the functional contributions of various brain areas in swallowing should be scientifically researched.OBJECTIVE: To identify the activation and characteristic of swallowing center in healthy adults using functional magnetic resonance imaging.DESIGN, TIME AND SETTING: An uncontrolled neuroimaging study was performed at the Outpatient Clinic, Department of Radiology, West China Hospital of Sichuan University between March and November 2008.PARTICIPANTS: Ten healthy right-handed volunteers, aged over 20 years with a mean age of (34.2 ±8.1) years, a range of 25-45 years and including five males and five females participated. A medical history was obtained from all potential subjects and all subjects were free of systemic diseases and neurological disorders.METHODS: The healthy volunteers were examined with event-related functional magnetic resonance imaging of blood oxygenation level-dependent while laryngeal swallow-related movements were recorded. Subjects were scanned during voluntary saliva swallowing and water bolus swallowing activation tasks. Data was processed using the General Linear Model. A voxel by voxel group comparison was performed using random effect analysis. Any cluster with a corrected P < 0.05 for spatial extent was considered significant.MAIN OUTCOME MEASURES: The cerebral cortical activation maps of voluntary swallowing of saliva and swallowing of water bolus in healthy adults were observed.RESULTS: A multifocal cortical representation of swallowing was in the precentral gyrus

  2. Characteristics of fMRI BOLD signal and its neurophysiological mechanism

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiaohu; Wu Yigen; Guo Shengli

    2007-01-01

    The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

  3. SElf-gated Non-Contrast-Enhanced FUnctional Lung imaging (SENCEFUL) using a quasi-random fast low-angle shot (FLASH) sequence and proton MRI.

    Science.gov (United States)

    Fischer, André; Weick, Stefan; Ritter, Christian O; Beer, Meinrad; Wirth, Clemens; Hebestreit, Helge; Jakob, Peter M; Hahn, Dietbert; Bley, Thorsten; Köstler, Herbert

    2014-08-01

    Obtaining functional information on the human lung is of tremendous interest in the characterization of lung defects and pathologies. However, pulmonary ventilation and perfusion maps usually require contrast agents and the application of electrocardiogram (ECG) triggering and breath holds to generate datasets free of motion artifacts. This work demonstrates the possibility of obtaining highly resolved perfusion-weighted and ventilation-weighted images of the human lung using proton MRI and the SElf-gated Non-Contrast-Enhanced FUnctional Lung imaging (SENCEFUL) technique. The SENCEFUL technique utilizes a two-dimensional fast low-angle shot (FLASH) sequence with quasi-random sampling of phase-encoding (PE) steps for data acquisition. After every readout, a short additional acquisition of the non-phase-encoded direct current (DC) signal necessary for self-gating was added. By sorting the quasi-randomly acquired data according to respiratory and cardiac phase derived from the DC signal, datasets of representative respiratory and cardiac cycles could be accurately reconstructed. By application of the Fourier transform along the temporal dimension, functional maps (perfusion and ventilation) were obtained. These maps were compared with dynamic contrast-enhanced (DCE, perfusion) as well as standard Fourier decomposition (FD, ventilation) reference datasets. All datasets were additionally scored by two experienced radiologists to quantify image quality. In addition, one initial patient examination using SENCEFUL was performed. Functional images of healthy volunteers and a patient diagnosed with hypoplasia of the left pulmonary artery and left-sided pulmonary fibrosis were successfully obtained. Perfusion-weighted images corresponded well to DCE-MRI data; ventilation-weighted images offered a significantly better depiction of the lung periphery compared with standard FD. Furthermore, the SENCEFUL technique hints at a potential clinical relevance by successfully detecting

  4. Screening for impaired renal function in outpatients before iodinated contrast injection: Comparing the Choyke questionnaire with a rapid point-of-care-test

    International Nuclear Information System (INIS)

    Highlights: • Iodinated intravenous contrast carries a low risk of contrast induced nephropathy (CIN). • Patients with eGFR less than 45 mL/min/1.73 m2 are particularly at risk for CIN. • The Choyke questionnaire is used to screen for impaired renal function in outpatients. • Choyke questionnaire is a good screening tool for eGFR less than 45 mL/min/1.73 m2. • Point of care test (POCT) for serum creatinine can reduce waiting time. - Abstract: Rationale and purpose: To determine the usefulness of the Choyke questionnaire with a creatinine point-of-care test (POCT) to detect impaired renal function amongst outpatients receiving intravenous iodinated contrast in a tertiary centre. Materials and methods: Between July and December 2012, 1361 outpatients had their serum creatinine determined by POCT and answered the Chokye questionnaire just before their examination. Results: Four hundred and eighty (35.2%) patients had at least one ‘Yes’ response. Forty-four patients (3.2%) had estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 and 14 patients (1.0%) have eGFR <45 mL/min/1.73 m2. Sensitivity, specificity, positive predictive value and negative predictive value of the Choyke criteria in detecting patients with eGFR <60 mL/min/1.73 m2 are respectively: 65.9%, 65.8%, 6.0% and 98.3% and to detect eGFR <45 mL/min/1.73 m2: 92.9%, 65.3%, 2.7% and 99.9%. Only ‘Yes’ responses to ‘Have you ever been told you have renal problems?’ and ‘Do you have diabetes mellitus?’ were statistically significant in predicting eGFR <45 mL/min/1.73 m2, with odds ratio 98.7 and 4.4 respectively. Conclusion: The Choyke questionnaire has excellent sensitivity and moderate-to-good specificity in detecting patients with <45 mL/min/1.73 m2, below this level it has been shown that risk of contrast induced nephropathy increases significantly, making it an effective screening tool. Also the use of POCT can potentially reduce waiting time

  5. Screening for impaired renal function in outpatients before iodinated contrast injection: Comparing the Choyke questionnaire with a rapid point-of-care-test

    Energy Technology Data Exchange (ETDEWEB)

    Too, C.W., E-mail: toochowwei@gmail.com [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Ng, W.Y., E-mail: ng.wai.yoong@sgh.com.sg [Department of Pathology, Singapore General Hospital, 20 College Road, Academia, Singapore 169856 (Singapore); Tan, C.C., E-mail: tan.chin.chong@sgh.com.sg [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Mahmood, M.I., E-mail: muhd.illyyas.mahmood@sgh.com.sg [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Tay, K.H., E-mail: tay.kiang.hiong@sgh.com.sg [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore)

    2015-07-15

    Highlights: • Iodinated intravenous contrast carries a low risk of contrast induced nephropathy (CIN). • Patients with eGFR less than 45 mL/min/1.73 m{sup 2} are particularly at risk for CIN. • The Choyke questionnaire is used to screen for impaired renal function in outpatients. • Choyke questionnaire is a good screening tool for eGFR less than 45 mL/min/1.73 m{sup 2}. • Point of care test (POCT) for serum creatinine can reduce waiting time. - Abstract: Rationale and purpose: To determine the usefulness of the Choyke questionnaire with a creatinine point-of-care test (POCT) to detect impaired renal function amongst outpatients receiving intravenous iodinated contrast in a tertiary centre. Materials and methods: Between July and December 2012, 1361 outpatients had their serum creatinine determined by POCT and answered the Chokye questionnaire just before their examination. Results: Four hundred and eighty (35.2%) patients had at least one ‘Yes’ response. Forty-four patients (3.2%) had estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m{sup 2} and 14 patients (1.0%) have eGFR <45 mL/min/1.73 m{sup 2}. Sensitivity, specificity, positive predictive value and negative predictive value of the Choyke criteria in detecting patients with eGFR <60 mL/min/1.73 m{sup 2} are respectively: 65.9%, 65.8%, 6.0% and 98.3% and to detect eGFR <45 mL/min/1.73 m{sup 2}: 92.9%, 65.3%, 2.7% and 99.9%. Only ‘Yes’ responses to ‘Have you ever been told you have renal problems?’ and ‘Do you have diabetes mellitus?’ were statistically significant in predicting eGFR <45 mL/min/1.73 m{sup 2}, with odds ratio 98.7 and 4.4 respectively. Conclusion: The Choyke questionnaire has excellent sensitivity and moderate-to-good specificity in detecting patients with <45 mL/min/1.73 m{sup 2}, below this level it has been shown that risk of contrast induced nephropathy increases significantly, making it an effective screening tool. Also the use of POCT can potentially

  6. Enhanced control of dorsolateral prefrontal cortex neurophysiology with real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback training and working memory practice.

    Science.gov (United States)

    Sherwood, Matthew S; Kane, Jessica H; Weisend, Michael P; Parker, Jason G

    2016-01-01

    Real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback can be used to train localized, conscious regulation of blood oxygen level-dependent (BOLD) signals. As a therapeutic technique, rt-fMRI neurofeedback reduces the symptoms of a variety of neurologic disorders. To date, few studies have investigated the use of self-regulation training using rt-fMRI neurofeedback to enhance cognitive performance. This work investigates the utility of rt-fMRI neurofeedback as a tool to enhance human cognition by training healthy individuals to consciously control activity in the left dorsolateral prefrontal cortex (DLPFC). A cohort of 18 healthy participants in the experimental group underwent rt-fMRI neurofeedback from the left DLPFC in five training sessions across two weeks while 7 participants in the control group underwent similar training outside the MRI and without rt-fMRI neurofeedback. Working memory (WM) performance was evaluated on two testing days separated by the five rt-fMRI neurofeedback sessions using two computerized tests. We investigated the ability to control the BOLD signal across training sessions and WM performance across the two testing days. The group with rt-fMRI neurofeedback demonstrated a significant increase in the ability to self-regulate the BOLD signal in the left DLPFC across sessions. WM performance showed differential improvement between testing days one and two across the groups with the highest increases observed in the rt-fMRI neurofeedback group. These results provide evidence that individuals can quickly gain the ability to consciously control the left DLPFC, and this training results in improvements of WM performance beyond that of training alone. PMID:26348555

  7. Independent component analysis applied to pharmacological magnetic resonance imaging (phMRI): new insights into the functional networks underlying panic attacks as induced by CCK-4.

    Science.gov (United States)

    Dieler, A C; Sämann, P G; Leicht, G; Eser, D; Kirsch, V; Baghai, T C; Karch, S; Schüle, C; Pogarell, O; Czisch, M; Rupprecht, R; Mulert, C

    2008-01-01

    Pharmacological magnetic resonance imaging (phMRI) is a method to study effects of psychopharmacological agents on neural activation. Changes of the blood oxygen level dependent (BOLD), the basis of functional MRI (fMRI), are typically obtained at relatively high sampling frequencies. This has more recently been exploited in the field of fMRI by applying independent component analysis (ICA), an explorative data analysis method decomposing activation into distinct neural networks. While already successfully used to investigate resting network and task-induced activity, its use in phMRI is new. Further extension of this method to tensorial probabilistic ICA (tensor PICA) allows to group similar brain activation across the anatomical, temporal, subject or session domain. This approach is useful for pharmacological experiments when no pharmacokinetic model exists. We exemplify this method using data from a placebo-controlled cholecystokinine-4 (CCK-4) injection experiment performed on 16 neuropsychiatrically and medically healthy males (age 25.6 +/- 4.2 years). Tensor PICA identified strong increases in activity in 12 networks. Comparison with results gained from the standard approach (voxelwise regression analysis) revealed good reproduction of areas previously associated with CCK-4 action, such as the anterior cingulate, orbitofrontal cortex, cerebellum, temporolateral, left parietal and insular areas, striatum, and precuneus. Several other components such as the dorsal anterior cingulate and medial prefrontal cortex were identified, suggesting higher sensitivity of the method. Exploration of the time courses of each activated network revealed differences, that might be lost when a fixed time course is modeled, e. g. neuronal responses to an acoustic warning signal prior to injection. Comparison of placebo and CCK-4 runs further showed that a proportion of networks are newly elicited by CCK-4 whereas other components are significantly active in the placebo conditions

  8. Event-related dynamics of glutamate and BOLD effects measured using functional magnetic resonance spectroscopy (fMRS) at 3T in a repetition suppression paradigm.

    Science.gov (United States)

    Apšvalka, Dace; Gadie, Andrew; Clemence, Matthew; Mullins, Paul G

    2015-09-01

    Proton MR spectroscopy ((1)H-MRS) complements other brain research methods by providing measures of neurometabolites noninvasively in a localized brain area. Improvements in MR scanner technologies, and data acquisition and analysis methods should allow functional (1)H-MRS (fMRS) to measure neurometabolite concentration changes during task-induced brain activation. The aim of the current study was to further develop event-related fMRS at 3T to investigate glutamate dynamics in response to repetition suppression. A secondary aim was to investigate the relationship between blood-oxygen-level-dependent (BOLD) responses and glutamate dynamics in the same paradigm at the same time. A novel approach of interleaved water-suppressed (metabolite) and unsuppressed (water) fMRS was used to simultaneously detect the event-related dynamics of glutamate and BOLD signal to repetition suppression in the lateral occipital cortex of thirteen (N=13) volunteers. On average, (1)H-MRS-visible glutamate increased after novel visual stimuli presentations by 12% and decreased by 11-13% on repeated compared to novel presentations. The BOLD signal, as measured by water peak amplitude changes, showed significant difference between Task and Rest trials, and, on a GLM based analysis of the time series, demonstrated a significant difference between the novel and repeated trials, however appeared to be decoupled from the glutamate response as no correlation was found between the two. These results are the first demonstration that reductions in neuronal activity typical of repetition suppression effects are reflected by reduced glutamatergic and BOLD measures, that glutamate and BOLD responses may not be coupled as previously thought, and that these changes and relationships can be measured simultaneously using event-related fMRS at 3T. PMID:26072254

  9. Synthesis, characterization and examination of Gd[DO3A-hexylamine]-functionalized silica nanoparticles as contrast agent for MRI-applications.

    Science.gov (United States)

    Feldmann, Verena; Engelmann, Jörn; Gottschalk, Sven; Mayer, Hermann A

    2012-01-15

    Spherical, nonporous and monodisperse silica nanoparticles (NPs) with a diameter of about 100 nm were synthesized and covalently functionalized with lanthanoid(III) (Ln=Gd or Y) chelate complexes, which serve as contrast agents (CAs) for magnetic resonance imaging (MRI). The materials were fully characterized after each synthetic step by different analytical methods, such as dynamic light scattering, scanning electron microscopy, DRIFT and NMR spectroscopy, thermogravimetry and elemental analysis, as well as zetapotential measurements. High surface concentrations of Gd(III) complexes (up to 50 μmol g(-1)) were determined by ICP-AES and T(1)-measurements, respectively. MRI experiments show the typical concentration-dependent increase of the longitudinal relaxation rate. T(1)-weighted images of samples with more than 25 μg NPs per 100 μL agar display a clear contrast enhancement in the agar layer. The transverse relaxivities r(2) of the materials are significantly higher than r(2) of the corresponding free Gd(III) complexes in water and medium, whereas the longitudinal relaxivities r(1) are slightly increased. Due to the high loading of Gd(III) complexes, the relaxivities per particle are remarkably high (up to 2.78×10(5) mM(-1) s(-1) for r(1)). Thus, new hybrid materials, based on nonporous silica NPs with high local relaxivity values were synthesized, which can serve as very effective CAs for MRI. PMID:22018761

  10. Changes in brain function and anatomical structure following treatment of hyperbaric oxygen for visual pathway abnormalities In 16 cases Evaluation of functional magnetic resonance Imaging combined with diffusion tensor imaging

    Institute of Scientific and Technical Information of China (English)

    Ziqian Chen; Ping Ni; Hui Xiao; Jinhua Chen; Gennian Qian; Youqiang Ye; Shangwen Xu; Jinliang Wang; Xizhang Yang

    2008-01-01

    BACKGROUND:There is a growing research focus on the combination of blood oxygenation level dependent functional magnetic resonance imaging(BOLD-fMRI)and diffusion tensor imaging(DTI)to evaluate visual cortical function and structural changes in the cerebrum,as well as morphological changes to the white matter fiber tracks,after visual pathway lesions.However,the combined application of BOLD-fMRI and DTI in treating of visual pathway abnormalities still requires further studies. OBJECTIVE:To observe and evaluate the effects of hyperbaric oxygen on visual pathway abnormalities,and to evaluate the characteristics of cerebral function and anatomic structural changes by using BOLD-fMRI combined with DTI technique. DESIGN:Case contrast observation. SETTING:Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA.PARTICIPANTS:Sixteen patients(9 males and 7 females,15-77 years old)with lateral or bilateral visual disorder induced by visual pathway lesions were selected from the Department of Neurology,Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA from January 2006 to May 2007.These patients comprised the lesion group.Measures of interventional therapy:hyperbaric oxygen of two normal atmospheres for three courses(10 d/course)and routine internal medicine treatment.In addition,12 healthy subjects of similar sex and age to the lesion group were regarded as the control group.The control group underwent routine ophthalmological and ocular fundus examinations; diagnostic results were normal. The experiment received confirmed consent from the local ethic committee,and all patients provided informed consent.METHODS:BOLD-fMRI and DTI manifestations in the lesion group were observed before and after hyperbaric oxygen intervention,and the results were compared with the control group.The subjects were positioned on their back,and BOLD-fMRI images were collected with the following GRE EPI sequence:TR= 2 000 ms,TE=40 ms,layer thickness=5 mm

  11. Assessment of sexual orientation using the hemodynamic brain response to visual sexual stimuli

    DEFF Research Database (Denmark)

    Ponseti, Jorge; Granert, Oliver; Jansen, Olav;

    2009-01-01

    reliability. AIM: To evaluate whether the spatial response pattern to sexual stimuli as revealed by a change in blood oxygen level-dependent (BOLD) signal can be used for individual classification of sexual orientation. METHODS: We used a preexisting functional MRI (fMRI) data set that had been acquired in a...... nonclinical sample of 12 heterosexual men and 14 homosexual men. During fMRI, participants were briefly exposed to pictures of same-sex and opposite-sex genitals. Data analysis involved four steps: (i) differences in the BOLD response to female and male sexual stimuli were calculated for each subject; (ii......) these contrast images were entered into a group analysis to calculate whole-brain difference maps between homosexual and heterosexual participants; (iii) a single expression value was computed for each subject expressing its correspondence to the group result; and (iv) based on these expression values...

  12. Uncertainty and confidence from the triple-network perspective

    DEFF Research Database (Denmark)

    White, Thomas P.; Engen, Nina Helkjær; Sørensen, Susan; Overgaard, Morten; Shergill, Sukhi S.

    2014-01-01

    Our subjective confidence about particular events is related to but independent from the objective certainty of the stimuli we encounter. Surprisingly, previous investigations of the neurophysiological correlates of confidence and uncertainty have largely been carried out separately. After...... systematically reviewing the blood oxygenation-level dependent functional magnetic resonance imaging (BOLD fMRI) literature, and splitting studies on the basis of their task requirements, a voxel-based meta-analysis was performed to identify: (i) those regions which are replicably modulated by the uncertainty of...... environmental conditions; (ii) those regions whose activity is robustly affected by our subjective confidence; and (iii) those regions differentially activated at these contrasting times. In further meta-analyses the consistency of activation between these judgement types was assessed. Increased activation was...

  13. Group Independent Component Analysis and Functional MRI Examination of Changes in Language Areas Associated with Brain Tumors at Different Locations

    OpenAIRE

    Wang, Liya; Chen, Dandan; Yang, Xiaofeng; Olson, Jeffrey J.; GOPINATH, KAUNDINYA; Fan, Tianning; Mao, Hui

    2013-01-01

    Object This study investigates the effect of tumor location on alterations of language network by brain tumors at different locations using blood oxygenation level dependent (BOLD) fMRI and group independent component analysis (ICA). Subjects and Methods BOLD fMRI data were obtained from 43 right handed brain tumor patients. Presurgical mapping of language areas was performed on all 43 patients with a picture naming task. All data were retrospectively analyzed using group ICA. Patents were di...

  14. Dopaminergic basis of the psychosis-prone personality investigated with functional magnetic resonance imaging of procedural learning

    OpenAIRE

    Ulrich Ettinger; Corr, Philip J.; Veena Kumari

    2013-01-01

    Previous evidence shows a reliable association between psychosis-prone (especially schizotypal) personality traits and performance on dopamine (DA)-sensitive tasks (e.g., prepulse inhibition and antisaccade). Here, we used blood oxygen level-dependent (BOLD) fMRI and an established procedural learning (PL) task to examine the dopaminergic basis of two aspects of psychosis-proneness (specific schizotypy and general psychoticism). Thirty healthy participants (final N = 26) underwent fMRI during...

  15. Three-dimensional anisotropy contrast MRI and functional MRI of the human brain. Clinical application to assess pyramidal tract in patients with brain tumor and infarction

    International Nuclear Information System (INIS)

    We describe and evaluate the findings of three-dimensional anisotropy contrast MR axonography (3DAC MRX) and functional MRI (fMRI) in brain tumor and infarction. We obtained diffusion-weighted images (DWI) in 28 patients including 23 brain tumors and 15 acute infarctions located in or near pyramidal tract. Three anisotropic DWIs were transformed into graduations color-coded as red, green and blue, and then composed to form a combined color 3DAC MRX. We also performed functional MRI in 7 of the 28 patients and compared with cortical mapping of 3DAC MRX. 3DAC MRX with 23 brain tumors showed that the ipsilateral pyramidal tract was either discontinuous due to impaired anisotropy (n=8) or compressed due to mass effect (n=15). In 10 patients of acute infarction with motor impairment, pyramidal tract involvement was visually more conspicuous on 3DAC MRX compared to standard DWI. On functional MRI, hand motor activation was observed between blue vertical directional colors of pre- and post central gyrus. In conclusion, 3DAC MRX is a new noninvasive approach for visualization of the white matter neuronal tract and provides the information concerning pyramidal tract involvement. (author)

  16. Development of x-ray scintillator functioning also as an analyser grating used in grating-based x-ray differential phase contrast imaging

    Institute of Scientific and Technical Information of China (English)

    Lei Yao-Hu; Liu Xin; Guo Jin-Chuan; Zhao Zhi-Gang; Niu Han-Ben

    2011-01-01

    In order to push the grating-based phase contrast imaging system to be used in hospital and laboratories, this paper designs and develops a novel structure of x-ray scintillator functioning also as an analyser grating, which has been proposed for grating-based x-ray differential phase contrast imaging. According to this design, the scintillator should have a periodical structure in one dimension with the pitch equaling the period of self-image of the phase grating at the Talbot distance, where one half of the pitch is pixellated and is made of x-ray sensitive fluorescent material, such as CsI(TI), and the remaining part of the pitch is made of x-ray insensitive material, such as silicon. To realize the design, a deep pore array with a high aspect ratio and specially designed grating pattern are successfully manufactured on 5 inch silicon wafer by the photo-assisted electrochemical etching method. The related other problems, such as oxidation-caused geometrical distortion, the filling of CsI(Tl)into deep pores and the removal of inside bubbles, have been overcome.Its pixel size, depth and grating pitch are 3 μLmx7.5 gm, 150 μm and 3 μm, respectively. The microstructure of the scintillator has been examined microscopically and macroscopically by scanning electron microscope and x-ray resolution chart testing, respectively. The preliminary measurements have shown that the proposed scintillator, also functioning as an analyser grating, has been successfully designed and developed.

  17. Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion

    NARCIS (Netherlands)

    Smeets, P.A.M.; Vidarsdottir, S.; Graaf, C. de; Stafleu, A.; Osch, M.J.P. van; Viergever, M.A.; Pijl, H.; Grond, J. van der

    2007-01-01

    We previously showed that hypothalamic neuronal activity, as measured by the blood oxygen level-dependent (BOLD) functional MRI signal, declines in response to oral glucose intake. To further explore the mechanism driving changes in hypothalamic neuronal activity in response to an oral glucose load,

  18. Bayesian model comparison in nonlinear BOLD fMRI hemodynamics

    DEFF Research Database (Denmark)

    Jacobsen, Danjal Jakup; Hansen, Lars Kai; Madsen, Kristoffer Hougaard

    2008-01-01

    Nonlinear hemodynamic models express the BOLD (blood oxygenation level dependent) signal as a nonlinear, parametric functional of the temporal sequence of local neural activity. Several models have been proposed for both the neural activity and the hemodynamics. We compare two such combined models...

  19. Isoflurane anesthesia is a valuable alternative for alpha-chloralose anesthesia in the forepaw stimulation model in rats.

    NARCIS (Netherlands)

    Sommers, M.G.J.; Egmond, J. van; Booij, L.H.D.J.; Heerschap, A.

    2009-01-01

    Isoflurane (ISO) can be a valuable alternative for alpha-chloralose (ACL) anesthesia in functional MRI (fMRI) studies. Therefore, we compared the efficacy of the blood oxygen level dependent (BOLD) effect in fMRI studies during ISO and ACL anesthesia sequentially in the same animals. After non-invas

  20. Influence of contrast morphogenetic features of urban constructed soils on the functioning of Moscow green lawn urban ecosystems: analysis based on the field model experiment

    Science.gov (United States)

    Epikhina, Anna; Vizirskaya, Mariya; Mazirov, Ilya; Vasenev, Vyacheslav; Vasenev, Ivan; Valentini, Riccardo

    2014-05-01

    Green lawns are the key element of the urban environment. They occupy a considerable part of the city area and locate in different urban functional zones. Urban constructed soils under green lawns have a unique spatial variability in chemical and morphogenetic features. So far, there is lack of information on the influence of morphogenetic features of urban soils on the functioning of the green lawn ecosystems especially in Moscow - the biggest megalopolis in Europe. Urban lawns perform a number of principal functions including both aesthetic and environmental. The role of the green lawn ecosystems in global carbon cycle is one of their main environmental functions. It is traditionally assessed through carbon stocks and fluxes in the basic ecosystem components. So far, such a data for the urban lawn ecosystems of the Moscow megapolis is lacking. In addition to environmental functions, green lawns perform an important ornamental role, which is also a critical criterion of their optimal functioning. Considering the variability of driving factors, influencing green lawns in urban environment, we carry out the model experiment in order to analyze "pure" effect of soil morphogenetic features. The current study aimed to analyze the influence of contrast morphogenetic features of urban constructed soils on the environmental and aesthetic functions of lawn ecosystems in Moscow megapolis basing in the model experiment. We carry out the model experiment located at the experimental field of the Russian State Agrarian University. Special transparent containers developed for the experiment, provided an option to observe soil morphogenetic features dynamics, including the depth and material of the organic transformation. At the same soil body inside the containers was united with the outside environment through the system of holes in the bottom and walls. The set of urban constructed soils includ four contrast types of the top soil (turf (T), turf-sand (TSa), turf-soil (TSo) and

  1. Functional lung MRI in chronic obstructive pulmonary disease: comparison of T1 mapping, oxygen-enhanced T1 mapping and dynamic contrast enhanced perfusion.

    Directory of Open Access Journals (Sweden)

    Bertram J Jobst

    Full Text Available Monitoring of regional lung function in interventional COPD trials requires alternative endpoints beyond global parameters such as FEV1. T1 relaxation times of the lung might allow to draw conclusions on tissue composition, blood volume and oxygen fraction. The aim of this study was to evaluate the potential value of lung Magnetic resonance imaging (MRI with native and oxygen-enhanced T1 mapping for the assessment of COPD patients in comparison with contrast enhanced perfusion MRI.20 COPD patients (GOLD I-IV underwent a coronal 2-dimensional inversion recovery snapshot flash sequence (8 slices/lung at room air and during inhalation of pure oxygen, as well as dynamic contrast-enhanced first-pass perfusion imaging. Regional distribution of T1 at room air (T1, oxygen-induced T1 shortening (ΔT1 and peak enhancement were rated by 2 chest radiologists in consensus using a semi-quantitative 3-point scale in a zone-based approach.Abnormal T1 and ΔT1 were highly prevalent in the patient cohort. T1 and ΔT1 correlated positively with perfusion abnormalities (r = 0.81 and r = 0.80; p&0.001, and with each other (r = 0.80; p<0.001. In GOLD stages I and II ΔT1 was normal in 16/29 lung zones with mildly abnormal perfusion (15/16 with abnormal T1. The extent of T1 (r = 0.45; p<0.05, ΔT1 (r = 0.52; p<0.05 and perfusion abnormalities (r = 0.52; p<0.05 showed a moderate correlation with GOLD stage.Native and oxygen-enhanced T1 mapping correlated with lung perfusion deficits and severity of COPD. Under the assumption that T1 at room air correlates with the regional pulmonary blood pool and that oxygen-enhanced T1 reflects lung ventilation, both techniques in combination are principally suitable to characterize ventilation-perfusion imbalance. This appears valuable for the assessment of regional lung characteristics in COPD trials without administration of i.v. contrast.

  2. Functional mapping of language networks in the normal brain using a word-association task

    Directory of Open Access Journals (Sweden)

    Ghosh Shantanu

    2010-01-01

    Full Text Available Background: Language functions are known to be affected in diverse neurological conditions, including ischemic stroke, traumatic brain injury, and brain tumors. Because language networks are extensive, interpretation of functional data depends on the task completed during evaluation. Aim: The aim was to map the hemodynamic consequences of word association using functional magnetic resonance imaging (fMRI in normal human subjects. Materials and Methods: Ten healthy subjects underwent fMRI scanning with a postlexical access semantic association task vs lexical processing task. The fMRI protocol involved a T2FNx01-weighted gradient-echo echo-planar imaging (GE-EPI sequence (TR 4523 ms, TE 64 ms, flip angle 90º with alternate baseline and activation blocks. A total of 78 scans were taken (interscan interval = 3 s with a total imaging time of 587 s. Functional data were processed in Statistical Parametric Mapping software (SPM2 with 8-mm Gaussian kernel by convolving the blood oxygenation level-dependent (BOLD signal with an hemodynamic response function estimated by general linear method to generate SPM{t} and SPM{F} maps. Results: Single subject analysis of the functional data (FWE-corrected, P≤0.001 revealed extensive activation in the frontal lobes, with overlaps among middle frontal gyrus (MFG, superior, and inferior frontal gyri. BOLD activity was also found in the medial frontal gyrus, middle occipital gyrus (MOG, anterior fusiform gyrus, superior and inferior parietal lobules, and to a smaller extent, the thalamus and right anterior cerebellum. Group analysis (FWE-corrected, P≤0.001 revealed neural recruitment of bilateral lingual gyri, left MFG, bilateral MOG, left superior occipital gyrus, left fusiform gyrus, bilateral thalami, and right cerebellar areas. Conclusions: Group data analysis revealed a cerebellar-occipital-fusiform-thalamic network centered around bilateral lingual gyri for word association, thereby indicating how these

  3. Functional mapping of language networks in the normal brain using a word-association task

    International Nuclear Information System (INIS)

    Language functions are known to be affected in diverse neurological conditions, including ischemic stroke, traumatic brain injury, and brain tumors. Because language networks are extensive, interpretation of functional data depends on the task completed during evaluation. The aim was to map the hemodynamic consequences of word association using functional magnetic resonance imaging (fMRI) in normal human subjects. Ten healthy subjects underwent fMRI scanning with a postlexical access semantic association task vs lexical processing task. The fMRI protocol involved a T2*-weighted gradient-echo echo-planar imaging (GE-EPI) sequence (TR 4523 ms, TE 64 ms, flip angle 90°) with alternate baseline and activation blocks. A total of 78 scans were taken (interscan interval = 3 s) with a total imaging time of 587 s. Functional data were processed in Statistical Parametric Mapping software (SPM2) with 8-mm Gaussian kernel by convolving the blood oxygenation level-dependent (BOLD) signal with an hemodynamic response function estimated by general linear method to generate SPM{t} and SPM{F} maps. Single subject analysis of the functional data (FWE-corrected, P≤0.001) revealed extensive activation in the frontal lobes, with overlaps among middle frontal gyrus (MFG), superior, and inferior frontal gyri. BOLD activity was also found in the medial frontal gyrus, middle occipital gyrus (MOG), anterior fusiform gyrus, superior and inferior parietal lobules, and to a smaller extent, the thalamus and right anterior cerebellum. Group analysis (FWE-corrected, P≤0.001) revealed neural recruitment of bilateral lingual gyri, left MFG, bilateral MOG, left superior occipital gyrus, left fusiform gyrus, bilateral thalami, and right cerebellar areas. Group data analysis revealed a cerebellar–occipital–fusiform–thalamic network centered around bilateral lingual gyri for word association, thereby indicating how these areas facilitate language comprehension by activating a semantic

  4. Work function contrast and energy band modulation between amorphous and crystalline Ge{sub 2}Sb{sub 2}Te{sub 5} films

    Energy Technology Data Exchange (ETDEWEB)

    Tong, H.; Yang, Z.; Yu, N. N.; Zhou, L. J.; Miao, X. S., E-mail: miaoxs@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-08-24

    The work function (WF) is of crucial importance to dominate the carrier transport properties of the Ge-Sb-Te based interfaces. In this letter, the electrostatic force microscopy is proposed to extract the WF of Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) films with high spatial and energy resolution. The measured WF of as-deposited amorphous GST is 5.34 eV and decreases drastically after the amorphous GST is crystallized by annealing or laser illumination. A 512 × 512 array 2D-WF map is designed to study the WF spatial distribution and shows a good consistency. The WF contrast between a-GST and c-GST is ascribed to band modulation, especially the modification of electron affinity including the contribution of charges or dipoles. Then, the band alignments of GST/n-Si heterostructures are obtained based on the Anderson's rule. Due to the band modulation, the I-V characteristics of a-GST/Si heterojunction and c-GST/Si heterojunction are very different from each other. The quantitative relationship is calculated by solving the Poisson's equation, which agrees well with the I-V measurements. Our findings not only suggest a way to further understand the electrical transport properties of Ge-Sb-Te based interfaces but also provide a non-touch method to distinguish crystalline area from amorphous matrix with high spatial resolution.

  5. CONTRAST SENSITIVITY IN AMBLYOPIA

    Institute of Scientific and Technical Information of China (English)

    1991-01-01

    Contrast sensitivity function(CSF) for sinusoid gratings of varying spatial frequencies was determined for each eye of 21 cases with unilateral amblyopia. The CSF of all amblyopic eyes, except one, showed reduced sensitivity when compared with the non-amblyopic eye of the same person. The curve showed reduction more significantly at middle and high spatial frequencies. The cut-off frequency was shifted toward lower spatial frequencies. The relationship between CSF and various degree of amblyopia was als...

  6. Functional imaging of the angiogenic switch in a transgenic mouse model of human breast cancer by dynamic contrast enhanced magnetic resonance imaging.

    Science.gov (United States)

    Consolino, Lorena; Longo, Dario Livio; Dastrù, Walter; Cutrin, Juan Carlos; Dettori, Daniela; Lanzardo, Stefania; Oliviero, Salvatore; Cavallo, Federica; Aime, Silvio

    2016-07-15

    Tumour progression depends on several sequential events that include the microenvironment remodelling processes and the switch to the angiogenic phenotype, leading to new blood vessels recruitment. Non-invasive imaging techniques allow the monitoring of functional alterations in tumour vascularity and cellularity. The aim of this work was to detect functional changes in vascularisation and cellularity through Dynamic Contrast Enhanced (DCE) and Diffusion Weighted (DW) Magnetic Resonance Imaging (MRI) modalities during breast cancer initiation and progression of a transgenic mouse model (BALB-neuT mice). Histological examination showed that BALB-neuT mammary glands undergo a slow neoplastic progression from simple hyperplasia to invasive carcinoma, still preserving normal parts of mammary glands. DCE-MRI results highlighted marked functional changes in terms of vessel permeability (K(trans) , volume transfer constant) and vascularisation (vp , vascular volume fraction) in BALB-neuT hyperplastic mammary glands if compared to BALB/c ones. When breast tissue progressed from simple to atypical hyperplasia, a strong increase in DCE-MRI biomarkers was observed in BALB-neuT in comparison to BALB/c mice (K(trans)  = 5.3 ± 0.7E-4 and 3.1 ± 0.5E-4; vp  = 7.4 ± 0.8E-2 and 4.7 ± 0.6E-2 for BALB-neuT and BALB/c, respectively) that remained constant during the successive steps of the neoplastic transformation. Consistent with DCE-MRI observations, microvessel counting revealed a significant increase in tumour vessels. Our study showed that DCE-MRI estimates can accurately detect the angiogenic switch at early step of breast cancer carcinogenesis. These results support the view that this imaging approach is an excellent tool to characterize microvasculature changes, despite only small portions of the mammary glands developed neoplastic lesions in a transgenic mouse model. PMID:26941084

  7. Failure of neural responses to safety cues in schizophrenia.

    Science.gov (United States)

    Holt, Daphne J; Coombs, Garth; Zeidan, Mohamed A; Goff, Donald C; Milad, Mohammed R

    2012-09-01

    CONTEXT Abnormalities in associative memory processes, such as Pavlovian fear conditioning and extinction, have been observed in schizophrenia. The retrieval of fear extinction memories (safety signals) may be particularly affected; although schizophrenic patients can extinguish conditioned fear, they show a deficit in retrieving fear extinction memories after a delay. The neurobiological basis of this abnormality is unknown, but clues have emerged from studies in rodents and humans demonstrating that the ventromedial prefrontal cortex (vmPFC) is a key mediator of extinction memory retrieval. OBJECTIVE To measure autonomic and neural responses during the acquisition and extinction of conditioned fear and the delayed recall of fear and extinction memories in patients with schizophrenia and healthy control participants. DESIGN Cross-sectional case control, functional magnetic resonance imaging study. SETTING Academic medical center. PARTICIPANTS Twenty schizophrenic patients and 17 healthy control participants demographically matched to the patient group. MAIN OUTCOME MEASURES Skin conductance and blood oxygen level-dependent responses. RESULTS During fear conditioning, schizophrenic patients showed blunted autonomic responses and abnormal blood oxygen level-dependent responses, relative to control participants, within the posterior cingulate gyrus, hippocampus, and other regions. Several of these abnormalities were linked to negative symptoms. During extinction learning, patients with schizophrenia and control participants showed comparable autonomic and neural responses. Twenty-four hours after the learning phases, the control subjects exhibited decreased fear and increased vmPFC responses in the extinction (safe) context as expected, indicating successful retention of the extinction memory. In contrast, the schizophrenic patients showed inappropriately elevated fear and poor vmPFC responses in the safe context. CONCLUSION Failure of extinction memory retrieval in

  8. Etiopathophysiological Assessment of Cases with Chronic Daily Headache: A Functional Magnetic Resonance Imaging Included Investigation

    Directory of Open Access Journals (Sweden)

    Akram Hashemi

    2012-10-01

    Full Text Available BACKGROUND: Chronic daily headache (CDH has gained little attention in functional neuro-imaging. When no structural abnormality is found in CDH, defining functional correlates between activated brain regions during headache bouts may provide unique insights towards understanding the pathophysiology of this type of headache.METHODS: We recruited four CDH cases for comprehensive assessments, including history taking, physical examinations and neuropsychological evaluations (The Addenbrooke’s Cognitive Evaluation, Beck’s Anxiety and Depression Inventories, Pittsburg Sleep Quality Index and Epworth Sleepiness Scale. Visual analogue scale (VAS was used to self-rate the intensity of headache. Patients then underwent electroencephalography (EEG, transcranial Doppler (TCD and functional magnetic resonance imaging (fMRI evaluations during maximal (VAS = 8-10/10 and off-headache (VAS = 0-3/10 conditions. Data were used to compare in both conditions. We also used BOLD (blood oxygen level dependent -group level activation map fMRI to possibly locate headache-related activated brain regions.RESULTS: General and neurological examinations as well as conventional MRIs were unremarkable. Neuropsychological assessments showed moderate anxiety and depression in one patient and minimal in others. Unlike three patients, maximal and off-headache TCD evaluation in one revealed increased middle cerebral artery blood flow velocity, at the maximal pain area. Although with no seizure history, the same patient’s EEG showed paroxysmal epileptic discharges during maximal headache intensity, respectively. Group level activation map fMRI showed activated classical pain matrix regions upon headache bouts (periaqueductal grey, substantia nigra and raphe nucleus, and markedly bilateral occipital lobes activation.CONCLUSION: The EEG changes were of note. Furthermore, the increased BOLD signals in areas outside the classical pain matrix (i.e. occipital lobes during maximal

  9. Evaluation on changes of early renal function in patients with diabetic nephropathy with contrast-enhanced ultrasound and its clinical significance

    International Nuclear Information System (INIS)

    Objective: To quantitatively assess the parameter alteration of renal blood flow in patients with diabetic nephropathy (DN) with the contrast-enhanced ultrasound (CEUS), and to evaluate value of the technique in diagnosis of early renal function changes of DN patients. Methods: 40 diabetic patients were equally divided into two group according to Mogensen's staging criteria: normal albuminuria group (group Ⅰ) and early DN group (group Ⅱ); and 15 cases of healthy volunteers were used as control group (N group) (n=15). All subjects were performed renal CEUS perfusion imaging, and QontraXt image analysis software was applied to select the region of interest (ROI) in the renal cortex. Then the time intensity curve (TIC) and kidney blood perfusion parameters were collected. Results: The renal blood perfusion was clearly shown in real time CEUS; compared with N group, the time to peak (TTP), regional blood volume (RBV), and mean transit time (MTT) of the patients in group Ⅰ were increased, there were significant differences (P<0.05); but there were no significant differences of derived peak intensity (DPI) and regional blood flow (RBF) between two groups (P>0.05). Compared with group Ⅰ and N group, the RBV, TTP and MTT of the patients were increased, the DPI and RBF were reduced in group Ⅱ, there were significant differences (P<0.05). Conclusion: The CEUS technical analysis can be used in evaluating renal abnormality of the DN patients in early period by showing the changes of renal perfusion parameters. (authors)

  10. Functional cortical reorganization in cases of cervical spondylotic myelopathy and changes associated with surgery.

    Science.gov (United States)

    Bhagavatula, Indira Devi; Shukla, Dhaval; Sadashiva, Nishanth; Saligoudar, Praveen; Prasad, Chandrajit; Bhat, Dhananjaya I

    2016-06-01

    OBJECTIVE The physiological mechanisms underlying the recovery of motor function after cervical spondylotic myelopathy (CSM) surgery are poorly understood. Neuronal plasticity allows neurons to compensate for injury and disease and to adjust their activities in response to new situations or changes in their environment. Cortical reorganization as well as improvement in corticospinal conduction happens during motor recovery after stroke and spinal cord injury. In this study the authors aimed to understand the cortical changes that occur due to CSM and following CSM surgery and to correlate these changes with functional recovery by using blood oxygen level-dependent (BOLD) functional MRI (fMRI). METHODS Twenty-two patients having symptoms related to cervical cord compression due to spondylotic changes along with 12 age- and sex-matched healthy controls were included in this study. Patients underwent cervical spine MRI and BOLD fMRI at 1 month before surgery (baseline) and 6 months after surgery. RESULTS Five patients were excluded from analysis because of technical problems; thus, 17 patients made up the study cohort. The mean overall modified Japanese Orthopaedic Association score improved in patients following surgery. Mean upper-extremity, lower-extremity, and sensory scores improved significantly. In the preoperative patient group the volume of activation (VOA) was significantly higher than that in controls. The VOA after surgery was reduced as compared with that before surgery, although it remained higher than that in the control group. In the preoperative patient group, activations were noted only in the left precentral gyrus (PrCG). In the postoperative group, activations were seen in the left postcentral gyrus (PoCG), as well as the PrCG and premotor and supplementary motor cortices. In postoperative group, the VOA was higher in both the PrCG and PoCG as compared with those in the control group. CONCLUSIONS There is over-recruitment of sensorimotor cortices

  11. Superparamagnetic maghemite nanoparticles from solid-state synthesis – Their functionalization towards peroral MRI contrast agent and magnetic carrier for trypsin immobilization

    Czech Academy of Sciences Publication Activity Database

    Kluchová, K.; Zbořil, R.; Tuček, J.; Pečová, M.; Zajoncová, L.; Šafařík, Ivo; Mašláň, M.; Marková, I.; Jančík, D.; Šebela, M.; Bartoňková, H.; Bellesi, V.; Novák, P.; Petridis, D.

    2009-01-01

    Roč. 30, - (2009), s. 2855-2863. ISSN 0142-9612 Institutional research plan: CEZ:AV0Z60870520 Keywords : maghemite * contrast agent * composites Subject RIV: CE - Biochemistry Impact factor: 7.365, year: 2009

  12. Reproducibility of the aortic input function (AIF) derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of the kidneys in a volunteer study

    Energy Technology Data Exchange (ETDEWEB)

    Mendichovszky, I.A. [Radiology and Physics Unit, University College London, Institute of Child Health, 30 Guilford Street, London WC1N1EH (United Kingdom)], E-mail: i.mendichovszky@ich.ucl.ac.uk; Cutajar, M. [Radiology and Physics Unit, University College London, Institute of Child Health, 30 Guilford Street, London WC1N1EH (United Kingdom)], E-mail: m.cutajar@ich.ucl.ac.uk; Gordon, I. [Radiology and Physics Unit, University College London, Institute of Child Health, 30 Guilford Street, London WC1N1EH (United Kingdom)], E-mail: i.gordon@ich.ucl.ac.uk

    2009-09-15

    Purpose: The aim of this study was to investigate the maximum height, area under the curve (AUC) and full width at half maximum (FWHM) of the aortic input function (AIF) in renal dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) studies. We evaluated the significance of choice of size for regions of interest (ROI) in the aorta, reproducibility and inter-observer agreement of AIF measurements in healthy volunteers for renal DCE-MRI studies. Methods: Fifteen healthy volunteers (nine males, six females), mean age 28.8 years (range 23-36 years), underwent two DCE-MRI kidney studies under similar conditions. Oblique-coronal DCE-MRI data volumes were acquired on a 1.5 T Siemens Avanto scanner with a 3D-FLASH pulse-sequence (TE/TR = 0.53/1.63 ms, flip angle = 17 deg., acquisition matrix = 128 x 104 voxels, strong fat saturation, PAT factor = 2 (GRAPPA) and 400 mm x 325 mm FOV). Each dynamic dataset consisted of 18 slices of 7.5 mm thickness (no gap) and an in-plane resolution of 3.1 mm x 3.1 mm, acquired every 2.5 s for >5 min. During the MR scan a dose of 0.05 mmol (0.1 mL) kg{sup -1} body weight of dimeglumine gadopentetate (Magnevist) was injected intravenously (2 mL s{sup -1} injection rate), followed by a 15 mL saline flush at the same rate, using a MR-compatible automated injector (Spectris). For each DCE-MRI study two observers each drew two ROIs in the abdominal aorta. Both ROIs were 3 voxels in width and had the same inferior limit (just above the emergence of the renal arteries from the aorta) but had different heights (4 voxels for one ROI and 10 voxels for the other). The dimensions, position and time of drawing the ROIs in the dynamic study were standardised between observers prior to data analysis. Mean signal intensities measured in the ROIs were plotted over time, representing the AIF. For each study, AIF 1 was derived from ROI 1 and AIF 2 was derived from ROI 2. Results and conclusion: Paired t-tests for inter-observer comparison on the

  13. A functional MRI study of the brain in stroke patients with upper-limb paralysis treated with constraint-induced movement therapy

    International Nuclear Information System (INIS)

    Objective: To investigate and compare the activation patterns of stroke patients with upper-limb paralysis using functional MRI before and after treatment with constraint-induced movement therapy (CIMT) so as to explore the mechanism of CIMT. Methods: Six patients in chronic stage of brain infarction who have functional disturbance in right upper-limb and 9 normal controls were entered into the study. All of the patients were asked to perform the thumb-to-index finger tapping task and underwent functional MRI before and two weeks after CIMT. The controls underwent fMRI of same protocol once. The patients' upper-limb function scores before and after CIMT were analyzed with SPSS 11.5 by paired t test. The fMRI data were analyzed with analysis of functional neurolmages (AFNI) software. The percentage of blood oxygenation level dependent (BOLD) signal change for the normal control was analyzed by one-sample t test to indentify the activated brain regions. The percentage change of BOLD signal for the patients before and after CIMT was compared to control's data by independent-samples t test. The percentage change of BOLD signal for the patients before and after CIMT was analyzed by paired-samples t test. The significant difference level was set P<0.05. Results: The fMRI showed the patients' activated brain regions before CIMT were similar to that of the controls', while the activation level was lower. There were wide areas activated to compensate the impaired function especially for the fight upper-limb. Before CIMT, the patients' score for fight upper-limb on the action research arm test was 27±4. After CIMT, the patients' score was 40±3, and the difference was significant (t=14.626, P<0.05), which indicated the improved function. These subjects also displayed cortical reorganization after CIMT on fMRI. The areas responsible for the right hand movement showed increased activation and the activation level at bilateral corpora striata thalami, and cerebella increased

  14. Corrective Contrast in Russian, in Contrast

    Directory of Open Access Journals (Sweden)

    Katja Jasinskaja

    2011-02-01

    Full Text Available In many languages markers of contrast, such as the English 'but', are also used to express correction: John didn't go to Paris, but to Berlin. The present paper tries to explain this cross-linguistic pattern and represents correction as a special case of contrast. It focuses on the Russian contrastive conjunction 'a' and argues that its corrective uses in combination with negation 'ne ... a' / 'a ne', which are traditionally viewed as a fixed collocation, are in fact co-occurrences of a general contrastive 'a' with constituent negation.

  15. The Voxel-Wise Functional Connectome Can Be Efficiently Derived from Co-activations in a Sparse Spatio-Temporal Point-Process.

    Science.gov (United States)

    Tagliazucchi, Enzo; Siniatchkin, Michael; Laufs, Helmut; Chialvo, Dante R

    2016-01-01

    Large efforts are currently under way to systematically map functional connectivity between all pairs of millimeter-scale brain regions based on large neuroimaging databases. The exploratory unraveling of this "functional connectome" based on functional Magnetic Resonance Imaging (fMRI) can benefit from a better understanding of the contributors to resting state functional connectivity. In this work, we introduce a sparse representation of fMRI data in the form of a discrete point-process encoding high-amplitude events in the blood oxygenation level-dependent (BOLD) signal and we show it contains sufficient information for the estimation of functional connectivity between all pairs of voxels. We validate this method by replicating results obtained with standard whole-brain voxel-wise linear correlation matrices in two datasets. In the first one (n = 71), we study the changes in node strength (a measure of network centrality) during deep sleep. The second is a large database (n = 1147) of subjects in which we look at the age-related reorganization of the voxel-wise network of functional connections. In both cases it is shown that the proposed method compares well with standard techniques, despite requiring only data on the order of 1% of the original BOLD signal time series. Furthermore, we establish that the point-process approach does not reduce (and in one case increases) classification accuracy compared to standard linear correlations. Our results show how large fMRI datasets can be drastically simplified to include only the timings of large-amplitude events, while still allowing the recovery of all pair-wise interactions between voxels. The practical importance of this dimensionality reduction is manifest in the increasing number of collaborative efforts aiming to study large cohorts of healthy subjects as well as patients suffering from brain disease. Our method also suggests that the electrophysiological signals underlying the dynamics of fMRI time series

  16. The Voxel-Wise Functional Connectome Can Be Efficiently Derived from Co-activations in a Sparse Spatio-Temporal Point-Process

    Science.gov (United States)

    Tagliazucchi, Enzo; Siniatchkin, Michael; Laufs, Helmut; Chialvo, Dante R.

    2016-01-01

    Large efforts are currently under way to systematically map functional connectivity between all pairs of millimeter-scale brain regions based on large neuroimaging databases. The exploratory unraveling of this “functional connectome” based on functional Magnetic Resonance Imaging (fMRI) can benefit from a better understanding of the contributors to resting state functional connectivity. In this work, we introduce a sparse representation of fMRI data in the form of a discrete point-process encoding high-amplitude events in the blood oxygenation level-dependent (BOLD) signal and we show it contains sufficient information for the estimation of functional connectivity between all pairs of voxels. We validate this method by replicating results obtained with standard whole-brain voxel-wise linear correlation matrices in two datasets. In the first one (n = 71), we study the changes in node strength (a measure of network centrality) during deep sleep. The second is a large database (n = 1147) of subjects in which we look at the age-related reorganization of the voxel-wise network of functional connections. In both cases it is shown that the proposed method compares well with standard techniques, despite requiring only data on the order of 1% of the original BOLD signal time series. Furthermore, we establish that the point-process approach does not reduce (and in one case increases) classification accuracy compared to standard linear correlations. Our results show how large fMRI datasets can be drastically simplified to include only the timings of large-amplitude events, while still allowing the recovery of all pair-wise interactions between voxels. The practical importance of this dimensionality reduction is manifest in the increasing number of collaborative efforts aiming to study large cohorts of healthy subjects as well as patients suffering from brain disease. Our method also suggests that the electrophysiological signals underlying the dynamics of fMRI time series

  17. Periodicity in tumor vasculature targeting kinetics of ligand-functionalized nanoparticles studied by dynamic contrast enhanced magnetic resonance imaging and intravital microscopy

    DEFF Research Database (Denmark)

    Hak, Sjoerd; Cebulla, Jana; Huuse, Else Marie;

    2014-01-01

    because angiogenesis plays an important role in various pathologies, but also since endothelial cell surface receptors are directly accessible for relatively large circulating nanoparticles. Typically, nanoparticle targeting towards these receptors is studied by analyzing the contrast distribution on...... kinetics. These kinetics will not only depend on nanoparticle characteristics, but also on receptor binding and recycling. In this study, we monitored the in vivo targeting kinetics of αvβ3-integrin specific nanoparticles with intravital microscopy and dynamic contrast enhanced magnetic resonance imaging...... periodicity in the accumulation kinetics of αvβ3-integrin targeted nanoparticles and hypothesize that this periodicity is caused by receptor binding, internalization and recycling dynamics. Taken together, this demonstrates that our experimental approach provides new insights in in vivo nanoparticle targeting...

  18. The application of preoperative functional MRI in neurosurgical treatment of intraoperative electrical stimulation for gliomas involving motor areas at 3 T

    International Nuclear Information System (INIS)

    Objective: To assess the value of preoperative blood oxygen level dependent (BOLD) 3 T functional magnetic resonance imaging (fMRI) to identify motor cortical areas in neurosurgical treatment of intraoperative electrical stimulation for gliomas involving motor areas. Methods: The study included 26 consecutive preoperative BOLD-fMRI sessions in patients with brain gliomas in or near senorimotor cortices. The bilateral hand movement fMRI paradigm was preformed in all patients. The BOLD data were analyzed by the workstation (Leonardo Syngo 2003A, Siemens)to obtain the BOLD-fMRI images, which were used to guide the preoperative neurosurgical planning. With guidance of preoperative mapping, all patients received microsurgery under anaesthesia retaining consciousness using intraoperative motor functional brain mapping with the method of direct electrical stimulations. The brain lesions were removed as far as possible in the case of eloquent areas preservation. The preoperative and postoperative KPS of all patients were operated to evaluate the state of patients. Results: The preoperative mappings of the hand area on primary sensorimotor cortex using BOLD-fMRI were obtained successfully in twenty-three of twenty-six patients. Under anaesthesia retaining consciousness, the primary motor area was monitored by the method of direct electrical stimulations with the guidance of preoperative BOLD-fMRI. There was good correlation between preoperative fMRI findings and intraoperative cortical stimulation. Furthermore, the preoperative mappings could make up for the un-monitored areas during operative cortical stimulation. For the 21 patients of the pre-KPS from 80.0 to 90.0, the pre-KPS and post-KPS are 85.7 and 95.2 respectively, and for the 5 patients of the pre-KPS from 40. 0 to 70.0, the pre-KPS and post-KPS are 68.0 and 90.0 respectively. Conclusion: The preoperative mapping of the hand area on primary sensorimotor cortex using BOLD-fMRI could non-invasively localize the

  19. Real-time phase-contrast x-ray imaging: a new technique for the study of animal form and function

    Directory of Open Access Journals (Sweden)

    Waters James S

    2007-03-01

    Full Text Available Abstract Background Despite advances in imaging techniques, real-time visualization of the structure and dynamics of tissues and organs inside small living animals has remained elusive. Recently, we have been using synchrotron x-rays to visualize the internal anatomy of millimeter-sized opaque, living animals. This technique takes advantage of partially-coherent x-rays and diffraction to enable clear visualization of internal soft tissue not viewable via conventional absorption radiography. However, because higher quality images require greater x-ray fluxes, there exists an inherent tradeoff between image quality and tissue damage. Results We evaluated the tradeoff between image quality and harm to the animal by determining the impact of targeted synchrotron x-rays on insect physiology, behavior and survival. Using 25 keV x-rays at a flux density of 80 μW/mm-2, high quality video-rate images can be obtained without major detrimental effects on the insects for multiple minutes, a duration sufficient for many physiological studies. At this setting, insects do not heat up. Additionally, we demonstrate the range of uses of synchrotron phase-contrast imaging by showing high-resolution images of internal anatomy and observations of labeled food movement during ingestion and digestion. Conclusion Synchrotron x-ray phase contrast imaging has the potential to revolutionize the study of physiology and internal biomechanics in small animals. This is the only generally applicable technique that has the necessary spatial and temporal resolutions, penetrating power, and sensitivity to soft tissue that is required to visualize the internal physiology of living animals on the scale from millimeters to microns.

  20. Cerebral responses to innocuous somatic pressure stimulation following aerobic exercise rehabilitation in chronic pain patients: a functional magnetic resonance imaging study

    Directory of Open Access Journals (Sweden)

    Micalos PS

    2014-08-01

    Full Text Available Peter S Micalos,1 Mayuresh S Korgaonkar,2 Eric J Drinkwater,3 Jack Cannon,3 Frank E Marino3 1School of Biomedical Sciences, Charles Sturt University, Bathurst, 2Brain Dynamics Centre, Westmead Millennium Institute, University of Sydney Medical School, Sydney, 3School of Human Movement Studies, Charles Sturt University, Bathurst, NSW, Australia Objective: The purpose of this research was to assess the functional brain activity and perceptual rating of innocuous somatic pressure stimulation before and after exercise rehabilitation in patients with chronic pain. Materials and methods: Eleven chronic pain patients and eight healthy pain-free controls completed 12 weeks of supervised aerobic exercise intervention. Perceptual rating of standardized somatic pressure stimulation (2 kg on the right anterior mid-thigh and brain responses during functional magnetic resonance imaging (fMRI were assessed at pre- and postexercise rehabilitation. Results: There was a significant difference in the perceptual rating of innocuous somatic pressure stimulation between the chronic pain and control groups (P=0.02 but no difference following exercise rehabilitation. Whole brain voxel-wise analysis with correction for multiple comparisons revealed trends for differences in fMRI responses between the chronic pain and control groups in the superior temporal gyrus (chronic pain > control, corrected P=0.30, thalamus, and caudate (control > chronic, corrected P=0.23. Repeated measures of the regions of interest (5 mm radius for blood oxygen level-dependent signal response revealed trend differences for superior temporal gyrus (P=0.06, thalamus (P=0.04, and caudate (P=0.21. Group-by-time interactions revealed trend differences in the caudate (P=0.10 and superior temporal gyrus (P=0.29. Conclusion: Augmented perceptual and brain responses to innocuous somatic pressure stimulation were shown in the chronic pain group compared to the control group; however, 12-weeks of exercise

  1. Contrasting effects of Elg1-RFC and Ctf18-RFC inactivation in the absence of fully functional RFC in fission yeast

    DEFF Research Database (Denmark)

    Kim, Jiyoung; Robertson, Kathryn; Mylonas, Katie J.;

    2005-01-01

    Proliferating cell nuclear antigen loading onto DNA by replication factor C (RFC) is a key step in eukaryotic DNA replication and repair processes. In this study, the C-terminal domain (CTD) of the large subunit of fission yeast RFC is shown to be essential for its function in vivo. Cells carrying...

  2. [Contrast sensitivity in glaucoma].

    Science.gov (United States)

    Bartos, D

    1989-05-01

    Author reports on results of the contrast sensitivity examinations using the Cambridge low-contrast lattice test supplied by Clement Clarke International LTD, in patients with open-angle glaucoma and ocular hypertension. In glaucoma patients there was observed statistically significant decrease of the contrast sensitivity. In patients with ocular hypertension decrease of the contrast sensitivity was in patients affected by corresponding changes of the visual field and of the optical disc. The main advantages of the Cambridge low-contrast lattice test were simplicity, rapidity and precision of its performance. PMID:2743444

  3. Contrast induced nephropathy

    DEFF Research Database (Denmark)

    Stacul, Fulvio; van der Molen, Aart J; Reimer, Peter;

    2011-01-01

    PURPOSE: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN). AREAS COVERED: Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic...... measures used to reduce the incidence of CIN, and the management of patients receiving metformin. Key Points • Definition, risk factors and prevention of contrast medium induced nephropathy are reviewed. • CIN risk is lower with intravenous than intra-arterial iodinated contrast medium. • eGFR of 45 ml....../min/1.73 m (2) is CIN risk threshold for intravenous contrast medium. • Hydration with either saline or sodium bicarbonate reduces CIN incidence. • Patients with eGFR ≥ 60 ml/min/1.73 m (2) receiving contrast medium can continue metformin normally....

  4. Contrast induced nephropathy

    DEFF Research Database (Denmark)

    Stacul, Fulvio; van der Molen, Aart J; Reimer, Peter;

    2011-01-01

    PURPOSE: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN). AREAS COVERED: Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic...... measures used to reduce the incidence of CIN, and the management of patients receiving metformin. Key Points • Definition, risk factors and prevention of contrast medium induced nephropathy are reviewed. • CIN risk is lower with intravenous than intra-arterial iodinated contrast medium. • eGFR of 45 ml....../min/1.73 m (2) is CIN risk threshold for intravenous contrast medium. • Hydration with either saline or sodium bicarbonate reduces CIN incidence. • Patients with eGFR = 60 ml/min/1.73 m (2) receiving contrast medium can continue metformin normally....

  5. Comparing the Effects of Isoflurane and Alpha Chloralose upon Mouse Physiology

    OpenAIRE

    Low, Lucie A.; Bauer, Lucy C.; Klaunberg, Brenda A.

    2016-01-01

    Functional magnetic resonance imaging of mice requires that the physiology of the mouse (body temperature, respiration and heart rates, blood pH level) be maintained in order to prevent changes affecting the outcomes of functional scanning, namely blood oxygenation level dependent (BOLD) measures and cerebral blood flow (CBF). The anesthetic used to sedate mice for scanning can have major effects on physiology. While alpha chloralose has been commonly used for functional imaging of rats, its ...

  6. Weighing the Evidence : -Determining and Contrasting the Characteristics and Functionality of Loom Weights and Spindle Whorls from the Garrison at Birka

    OpenAIRE

    Thorin, Ida

    2012-01-01

    The focus for this study is the illumination of the function of loom weights and their purpose within the warp-weighted loom. This study deals with Iron Age loom weights excavated at Birka, within the area known as the Garrison. This category of objects was originally classified as being fragments of bellow shields, an interpretation seemingly more corresponding with the site’s traditional interpretation. In order to give a fuller depiction of the textile production as a whole, spindle whorls...

  7. Changes in pools of depsidones and melanins, and their function, during growth and acclimation under contrasting natural light in the lichen Lobaria pulmonaria.

    Science.gov (United States)

    McEvoy, Maria; Gauslaa, Yngvar; Solhaug, Knut Asbjørn

    2007-01-01

    This study analysed relationships between secondary chemistry, lichen growth rates and external habitat factors for two groups of UV-B-absorbing secondary compounds in the lichen Lobaria pulmonaria in order to test some hypotheses on their formation and function. Medullary depsidones and cortical melanins were quantified in thalli transplanted to three successional forest stands (shaded young forest, open old forest, sun-exposed clear-cut area) and subjected to different watering regimes (spraying with water, water + nitrogen, no spraying). Growth rates were already known. The total concentration of all seven depsidones was constant across the entire range of growth rates and sun exposures, showing that these depsidones serve functions other than photoprotection. Thalli from the well-lit transplantation sites had the highest synthesis of melanins. Within each forest type there was a trade-off between growth and melanin synthesis. Melanins and photosynthetic acclimation enhanced survival on a subsequent exposure to high light intensity, despite excessive temperatures resulting from higher absorption of solar energy in melanic thalli relative to pale thalli. In conclusion, the highly responsive melanic pigments play a photoprotective role in light acclimation, whereas the constant amount of depsidones across a wide spectrum of growth ranges and irradiances is consistent with herbivore defence functions. PMID:17587375

  8. The velocity encoded phase contrast MRI study of normal calf muscle contractile function of vivo during ankle flexion and extension movement

    International Nuclear Information System (INIS)

    Objective: To explore the characteristics of calf muscle movement of the normal volunteer in vivo by velocity encoded phase contrast MRI (VE-PC MRI). Methods: Twenty four healthy subjects were divided into the young group (30-40 years) and the elderly group (60-78 years). All subjects were positioned on the scanner table and did ankles flexion-extension voluntary movement, the moving images of tibialis anterior muscles (TA), medial gastrocnemius (MG) and soleus muscle (SOL) on the left were scanned with VE-PC MRI. The calf muscles contraction velocity were analyzed by software. The Mann-Whitney U test was used for comparison of calf muscles contraction velocity in vivo between the young group and the elderly group. Results: During cyclic ankle flexion-extension, dorsiflexion phase (1-10 phases)in the two groups, TA showed concentric contraction, plantar flexion phase (11-20 phases), MG and SOL did concentric contraction. At 3-6 phases during dorsiflexion, velocity of TA (M value: -37.66, -53.00, -60.66, -56.00 mm/s) in the young group is higher than in the elderly group (M-value: -30.33, -42.49, -53.00, -48.67 mm/s), at 13-15 phases during plantar flexion, velocity of MG (M-value: -47.66, -60.00, -66.33 mm/s) in the young group showed higher velocity than in the elderly group (M-value: -25.17, -37.99, -50.98 mm/s), at 12-14 phases during plantar flexion, SOL showed higher velocity in the young group (M-value: -27.21, -40.10, -49.13 mm/s) than in the elderly group (M-value: -20.66, -29.61, -37.16 mm/s) (all P <0.05). Conclusions: During active ankle cyclic flexion-extension movement, velocity of TA, MG and SOL in the elderly group are decreased as compared to the young group. VE-PC MRI can reflect biomechanical characteristics of calf muscle in vivo, and provide a new kind of measurement for lower extremities. (authors)

  9. Measuring hepatic functional reserve using low temporal resolution Gd-EOB-DTPA dynamic contrast-enhanced MRI: a preliminary study comparing galactosyl human serum albumin scintigraphy with indocyanine green retention

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kazuhiro; Hashimoto, Tsuyoshi; Araki, Yoichi; Akata, Soichi; Tokuuye, Koichi [Tokyo Medical University, Department of Radiology, Tokyo (Japan); Ledsam, Joseph; Sourbron, Steven [University of Leeds, Division of Medical Physics, Leeds (United Kingdom)

    2014-01-15

    To investigate if tracer kinetic modelling of low temporal resolution dynamic contrast-enhanced (DCE) MRI with Gd-EOB-DTPA could replace technetium-99 m galactosyl human serum albumin (GSA) single positron emission computed tomography (SPECT) and indocyanine green (ICG) retention for the measurement of liver functional reserve. Twenty eight patients awaiting liver resection for various cancers were included in this retrospective study that was approved by the institutional review board. The Gd-EOB-DTPA MRI sequence acquired five images: unenhanced, double arterial phase, portal phase, and 4 min after injection. Intracellular contrast uptake rate (UR) and extracellular volume (Ve) were calculated from DCE-MRI, along with the ratio of GSA radioactivity of liver to heart-plus-liver and per cent of cumulative uptake from 15-16 min (LHL15 and LU15, respectively) from GSA-scintigraphy. ICG retention at 15 min, Child-Pugh cirrhosis score (CPS) and postoperative Inuyama fibrosis criteria were also recorded. Statistical analysis was with Spearman rank correlation analysis. Comparing MRI parameters with the reference methods, significant correlations were obtained for UR and LHL15, LU15, ICG15 (all 0.4-0.6, P < 0.05); UR and CPS (-0.64, P < 0.001); Ve and Inuyama (0.44, P < 0.05). Measures of liver function obtained by routine Gd-EOB-DTPA DCE-MRI with tracer kinetic modelling may provide a suitable method for the evaluation of liver functional reserve. (orig.)

  10. Multimodality Functional Imaging in Radiation Therapy Planning: Relationships between Dynamic Contrast-Enhanced MRI, Diffusion-Weighted MRI, and 18F-FDG PET

    Directory of Open Access Journals (Sweden)

    Moisés Mera Iglesias

    2015-01-01

    Full Text Available Objectives. Biologically guided radiotherapy needs an understanding of how different functional imaging techniques interact and link together. We analyse three functional imaging techniques that can be useful tools for achieving this objective. Materials and Methods. The three different imaging modalities from one selected patient are ADC maps, DCE-MRI, and 18F-FDG PET/CT, because they are widely used and give a great amount of complementary information. We show the relationship between these three datasets and evaluate them as markers for tumour response or hypoxia marker. Thus, vascularization measured using DCE-MRI parameters can determine tumour hypoxia, and ADC maps can be used for evaluating tumour response. Results. ADC and DCE-MRI include information from 18F-FDG, as glucose metabolism is associated with hypoxia and tumour cell density, although 18F-FDG includes more information about the malignancy of the tumour. The main disadvantage of ADC maps is the distortion, and we used only low distorted regions, and extracellular volume calculated from DCE-MRI can be considered equivalent to ADC in well-vascularized areas. Conclusion. A dataset for achieving the biologically guided radiotherapy must include a tumour density study and a hypoxia marker. This information can be achieved using only MRI data or only PET/CT studies or mixing both datasets.

  11. Evaluation of ECG gated RI angiocardiography for measurement of left ventricular function and its clinical application. Comparison with contrast cineangiography and application to pre and post treatment observation

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Shun; Morishita, Takashi (Toho Univ., Tokyo (Japan). School of Medicine)

    1983-03-01

    Cardiac function was examined by the radio-isotope (RI) angiocardiography method in 57 patients with various heart diseases and 8 healthy subjects. In addition, the cardiac catheter examination was performed for comparison in 49 of the heart disease patients. After sup(99m)Tc-HSA was injected into the right antecubital vein by flush method, the electro-cardiogram was synchronized to obtain data. The data were analyzed with a computer and 9 parameters of the cardiac function were calculated: cardiac output (CO), ejection fraction (EF), pre-ejection period (PEP), left ventricular ejection time (LVET), left ventricular rapid filling time (LVRFT), left ventricular slow filling time (LVSFT), EF/LVET, EF/LVDT, and left ventricular end diastolic volume (LVEDV). When the RI method was compared with the cineangiogram, a significant correlation was found in all parameters: r = 0.728 (p < 0.01) in CO, r = 0.89 (p < 0.01) in EF, r = 0.825 (p < 0.001) in LVEDV, etc. Moreover, it is suggested that this method can be repeatedly applied to investigate the progress following an operation of the heart and the alteration of essential hypertension through drug treatment.

  12. Compressive Phase Contrast Tomography

    OpenAIRE

    Maia, Filipe

    2010-01-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-R...

  13. Simultaneous fMRI-PET of the Opioidergic Pain System in Human Brain

    OpenAIRE

    Wey, HY; Catana, C.; Hooker, JM; Dougherty, DD; Knudsen, GM; Wang, DJJ; Chonde, DB; Rosen, BR; Gollub, RL; Kong, J.

    2014-01-01

    MRI and PET provide complementary information for studying brain function. While the potential use of simultaneous MRI/PET for clinical diagnostic and disease staging has been demonstrated recently; the biological relevance of concurrent functional MRI-PET brain imaging to dissect neurochemically distinct components of the blood oxygenation level dependent (BOLD) fMRI signal has not yet been shown. We obtained sixteen fMRI-PET data sets from eight healthy volunteers. Each subject participated...

  14. The influence of parental history of Alzheimer's disease and apolipoprotein E ε4 on the BOLD signal during recognition memory

    OpenAIRE

    Xu, Guofan; McLaren, Donald G.; Ries, Michele L.; Fitzgerald, Michele E.; Barbara B. Bendlin; Howard A. Rowley; Sager, Mark A.; Atwood, Craig; Asthana, Sanjay; Johnson, Sterling C.

    2008-01-01

    First-degree family history (FH) of sporadic Alzheimer's disease and the apolipoprotein E ε4 allele (APOE4) are risk factors for Alzheimer's disease that may affect brain function prior to onset of clinical symptoms. In this functional MRI (fMRI) study, we used an episodic recognition task that required discrimination of previously viewed (PV) and novel (NV) faces to examine differences in blood oxygen level dependent (BOLD) signal due to risk factors in 74 middle-aged cognitively normal indi...

  15. Amplitude of Low Frequency Fluctuation Abnormalities in Adolescents with Online Gaming Addiction

    OpenAIRE

    Yuan, Kai; Jin, Chenwang; Cheng, Ping; Yang, Xuejuan; DONG, tao; Bi, Yanzhi; Xing, Lihong; von Deneen, Karen M.; Yu, Dahua; Liu, Junyu; Liang, Jun; CHENG, TINGTING; Qin, Wei; Tian, Jie

    2013-01-01

    The majority of previous neuroimaging studies have demonstrated both structural and task-related functional abnormalities in adolescents with online gaming addiction (OGA). However, few functional magnetic resonance imaging (fMRI) studies focused on the regional intensity of spontaneous fluctuations in blood oxygen level-dependent (BOLD) during the resting state and fewer studies investigated the relationship between the abnormal resting-state properties and the impaired cognitive control abi...

  16. A contrastive analysis of English versions of Song You Ren from the perspective of textual-function theory%语篇功能视角下《送友人》英译本的对比分析

    Institute of Scientific and Technical Information of China (English)

    范燕

    2014-01-01

    应用韩礼德三大元语言功能之一的语篇功能来对比分析《送友人》的两个不同译本。重点分析主位结构、信息结构和衔接这三个方面的差异对于译文的影响,最后得出语篇功能对于古诗英译翻译批评研究有很好的可操作性和可行性,语篇功能在古诗英译评价体系中有重要作用。用语篇功能理论对《送友人》进行英汉对比分析可以帮助拓宽译者翻译诗歌的思路,相关理论对诗歌译文评价标准也有很好的参考价值。%This paper makes a contrastive analysis of two different English versions of the poem “farewell to a friend” by using the textual-function theory ,one of the three Meta functions of language proposed by Halliday .It an-alyzes the influence of the theme-rheme construction , informative construction and coherence upon the translated versions before concluding that the textual function theory is practicable in the critical research and the evaluation system of the translation of Chinese poems .A Contrastive analysis of two different versions of the poem from the per-spective of the textual function theory riches the ideas of the translator ,and the textual function theory will shed a new light upon the evaluation system of the poem's translated versions .

  17. Arterial input function of an optical tracer for dynamic contrast enhanced imaging can be determined from pulse oximetry oxygen saturation measurements

    Science.gov (United States)

    Elliott, Jonathan T.; Wright, Eric A.; Tichauer, Kenneth M.; Diop, Mamadou; Morrison, Laura B.; Pogue, Brian W.; Lee, Ting-Yim; St. Lawrence, Keith

    2012-12-01

    In many cases, kinetic modeling requires that the arterial input function (AIF)—the time-dependent arterial concentration of a tracer—be characterized. A straightforward method to measure the AIF of red and near-infrared optical dyes (e.g., indocyanine green) using a pulse oximeter is presented. The method is motivated by the ubiquity of pulse oximeters used in both preclinical and clinical applications, as well as the gap in currently available technologies to measure AIFs in small animals. The method is based on quantifying the interference that is observed in the derived arterial oxygen saturation (SaO2) following a bolus injection of a light-absorbing dye. In other words, the change in SaO2 can be converted into dye concentration knowing the chromophore-specific extinction coefficients, the true arterial oxygen saturation, and total hemoglobin concentration. A simple error analysis was performed to highlight potential limitations of the approach, and a validation of the method was conducted in rabbits by comparing the pulse oximetry method with the AIF acquired using a pulse dye densitometer. Considering that determining the AIF is required for performing quantitative tracer kinetics, this method provides a flexible tool for measuring the arterial dye concentration that could be used in a variety of applications.

  18. Contrasting deficits on executive functions in Chinese delinquent adolescents with attention deficit and hyperactivity disorder symptoms and/or reading disability.

    Science.gov (United States)

    Poon, Kean; Ho, Connie S-H

    2014-11-01

    Many studies reported high prevalence of reading disability (RD) and attention deficit hyperactivity disorder (ADHD) among delinquent adolescents. Very few have examined their cognitive profile. The present study compared the executive functions (EFs) and severity of delinquency in delinquent adolescents with RD and/or ADHD symptoms (AS). Delinquents with AS (n=29), RD (n=24), comorbidity AS+RD (n=35) were recruited from juvenile institutions along with typically developing controls (n=29) from local schools; all completed EF assessments and self-report questionnaires on delinquency. Results showed that pure AS group exhibited impaired inhibition while the pure RD group was weak in processing speed and visual memory. The comorbidity group showed unique impairments in interference control and significantly higher delinquency severity. The present findings suggest that comorbidity AS+RD may influence delinquency severity. It also provides a more comprehensive picture of the unique EF deficits associated with different groups, allowing for better matching for future identification and intervention programme. PMID:25128789

  19. Toward Critical Contrastive Rhetoric

    Science.gov (United States)

    Kubota, Ryuko; Lehner, Al

    2004-01-01

    A traditional approach to contrastive rhetoric has emphasized cultural difference in rhetorical patterns among various languages. Despite its laudable pedagogical intentions to raise teachers' and students' cultural and rhetorical awareness in second language writing, traditional contrastive rhetoric has perpetuated static binaries between English…

  20. Edaphic, structural and physiological contrasts across Amazon Basin forest-savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function

    Science.gov (United States)

    Lloyd, J.; Domingues, T. F.; Schrodt, F.; Ishida, F. Y.; Feldpausch, T. R.; Saiz, G.; Quesada, C. A.; Schwarz, M.; Torello-Raventos, M.; Gilpin, M.; Marimon, B. S.; Marimon-Junior, B. H.; Ratter, J. A.; Grace, J.; Nardoto, G. B.; Veenendaal, E.; Arroyo, L.; Villarroel, D.; Killeen, T. J.; Steininger, M.; Phillips, O. L.

    2015-11-01

    Sampling along a precipitation gradient in tropical South America extending from ca. 0.8 to 2.0 m a-1, savanna soils had consistently lower exchangeable cation concentrations and higher C / N ratios than nearby forest plots. These soil differences were also reflected in canopy averaged leaf traits with savanna trees typically having higher leaf mass per unit area but lower mass-based nitrogen (Nm) and potassium (Km). Both Nm and Km also increased with declining mean annual precipitation (PA), but most area-based leaf traits such as leaf photosynthetic capacity showed no systematic variation with PA or vegetation type. Despite this invariance, when taken in conjunction with other measures such as mean canopy height, area-based soil exchangeable potassium content, [K]sa , proved to be an excellent predictor of several photosynthetic properties (including 13C isotope discrimination). Moreover, when considered in a multivariate context with PA and soil plant available water storage capacity (θP) as covariates, [K]sa also proved to be an excellent predictor of stand-level canopy area, providing drastically improved fits as compared to models considering just PA and/or θP. Neither calcium, nor magnesium, nor soil pH could substitute for potassium when tested as alternative model predictors (ΔAIC > 10). Nor for any model could simple soil texture metrics such as sand or clay content substitute for either [K]sa or θP. Taken in conjunction with recent work in Africa and the forests of the Amazon Basin, this suggests - in combination with some newly conceptualised interacting effects of PA and θP also presented here - a critical role for potassium as a modulator of tropical vegetation structure and function.

  1. Edaphic, structural and physiological contrasts across Amazon Basin forest–savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function

    Directory of Open Access Journals (Sweden)

    J. Lloyd

    2015-11-01

    C / N ratios than nearby forest plots. These soil differences were also reflected in canopy averaged leaf traits with savanna trees typically having higher leaf mass per unit area but lower mass-based nitrogen (Nm and potassium (Km. Both Nm and Km also increased with declining mean annual precipitation (PA, but most area-based leaf traits such as leaf photosynthetic capacity showed no systematic variation with PA or vegetation type. Despite this invariance, when taken in conjunction with other measures such as mean canopy height, area-based soil exchangeable potassium content, [K]sa , proved to be an excellent predictor of several photosynthetic properties (including 13C isotope discrimination. Moreover, when considered in a multivariate context with PA and soil plant available water storage capacity (θP as covariates, [K]sa also proved to be an excellent predictor of stand-level canopy area, providing drastically improved fits as compared to models considering just PA and/or θP. Neither calcium, nor magnesium, nor soil pH could substitute for potassium when tested as alternative model predictors (ΔAIC > 10. Nor for any model could simple soil texture metrics such as sand or clay content substitute for either [K]sa or θP. Taken in conjunction with recent work in Africa and the forests of the Amazon Basin, this suggests – in combination with some newly conceptualised interacting effects of PA and θP also presented here – a critical role for potassium as a modulator of tropical vegetation structure and function.

  2. Edaphic, structural and physiological contrasts across Amazon Basin forest-savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function

    Directory of Open Access Journals (Sweden)

    J. Lloyd

    2015-05-01

    C/N ratios than nearby forest plots. These soil differences were also reflected in canopy averaged leaf traits with savanna trees typically having higher leaf mass per unit area but lower mass-based nitrogen (Nm and potassium (Km. Both Nm and Km also increased with declining mean annual precipitation (PA, but most area-based leaf traits such as leaf photosynthetic capacity showed no systematic variation with PA or vegetation type. Despite this invariance, when taken in conjunction with other measures such mean canopy height, area-based soil exchangeable potassium content, [K]sa, proved to be an excellent predictor of several photosynthetic properties (including 13C isotope discrimination. Moreover, when considered in a multivariate context with PA and soil plant available water storage capacity (θP as covariates, [K]sa also proved to be an excellent predictor of stand-level canopy area, providing drastically improved fits as compared to models considering just PA and/or θP. Neither calcium, magnesium nor soil pH could substitute for potassium when tested as alternative model predictors (ΔAIC > 10. Nor for any model could simple soil texture metrics such as sand or clay content substitute for either [K]sa or θP. Taken in conjunction with recent work in Africa and the forests of the Amazon Basin this suggests – in combination with some newly conceptualised interacting effects of PA and θP also presented here – a critical role for potassium as a modulator of tropical vegetation structure and function.

  3. Functionalized synchrotron in-line phase-contrast computed tomography: a novel approach for simultaneous quantification of structural alterations and localization of barium-labelled alveolar macrophages within mouse lung samples

    Energy Technology Data Exchange (ETDEWEB)

    Dullin, Christian, E-mail: christian.dullin@med.uni-goettingen.de [University Medical Center Göttingen, Robert Koch Strasse 40, 37075 Göttingen (Germany); Monego, Simeone dal [Cluster in Biomedicine, AREA Science Park Basovizza, Trieste (Italy); Larsson, Emanuel [Elettra Sincrotrone Trieste, Strada Statale 14, km 163.5 in AREA Science Park, 34149 Basovizza (Trieste) (Italy); University of Trieste, Trieste (Italy); Linköping University, SE-581 83 Linkoeping (Sweden); Mohammadi, Sara [Elettra Sincrotrone Trieste, Strada Statale 14, km 163.5 in AREA Science Park, 34149 Basovizza (Trieste) (Italy); Krenkel, Martin [University of Göttingen, Göttingen (Germany); Garrovo, Chiara; Biffi, Stefania [IRCCS Burlo Garofolo, Trieste (Italy); Lorenzon, Andrea [Cluster in Biomedicine, AREA Science Park Basovizza, Trieste (Italy); Markus, Andrea [University Medical Center Göttingen, Robert Koch Strasse 40, 37075 Göttingen (Germany); Napp, Joanna [University Medical Center Göttingen, Robert Koch Strasse 40, 37075 Göttingen (Germany); Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen (Germany); University Medical Center Göttingen, Robert Koch Strasse 40, 37075 Göttingen (Germany); Salditt, Tim [University of Göttingen, Göttingen (Germany); Accardo, Agostino [University of Trieste, Trieste (Italy); Alves, Frauke [University Medical Center Göttingen, Robert Koch Strasse 40, 37075 Göttingen (Germany); Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen (Germany); University Medical Center Göttingen, Robert Koch Strasse 40, 37075 Göttingen (Germany); Tromba, Giuliana [Elettra Sincrotrone Trieste, Strada Statale 14, km 163.5 in AREA Science Park, 34149 Basovizza (Trieste) (Italy)

    2015-01-01

    This study presents an approach to increase the sensitivity of lung computed tomography (CT) imaging by utilizing in-line phase contrast CT in combination with single-distance phase-retrieval algorithms and a dedicated image-processing regime. As demonstrated here, functional CT imaging can be achieved for the assessment of both structural alterations in asthmatic mouse lung tissue and the accumulation pattern of instilled barium-sulfate-labelled macrophages in comparison with healthy controls. Functionalized computed tomography (CT) in combination with labelled cells is virtually non-existent due to the limited sensitivity of X-ray-absorption-based imaging, but would be highly desirable to realise cell tracking studies in entire organisms. In this study we applied in-line free propagation X-ray phase-contrast CT (XPCT) in an allergic asthma mouse model to assess structural changes as well as the biodistribution of barium-labelled macrophages in lung tissue. Alveolar macrophages that were barium-sulfate-loaded and fluorescent-labelled were instilled intratracheally into asthmatic and control mice. Mice were sacrificed after 24 h, lungs were kept in situ, inflated with air and scanned utilizing XPCT at the SYRMEP beamline (Elettra Synchrotron Light Source, Italy). Single-distance phase retrieval was used to generate data sets with ten times greater contrast-to-noise ratio than absorption-based CT (in our setup), thus allowing to depict and quantify structural hallmarks of asthmatic lungs such as reduced air volume, obstruction of airways and increased soft-tissue content. Furthermore, we found a higher concentration as well as a specific accumulation of the barium-labelled macrophages in asthmatic lung tissue. It is believe that XPCT will be beneficial in preclinical asthma research for both the assessment of therapeutic response as well as the analysis of the role of the recruitment of macrophages to inflammatory sites.

  4. Functionalized synchrotron in-line phase-contrast computed tomography: a novel approach for simultaneous quantification of structural alterations and localization of barium-labelled alveolar macrophages within mouse lung samples

    International Nuclear Information System (INIS)

    This study presents an approach to increase the sensitivity of lung computed tomography (CT) imaging by utilizing in-line phase contrast CT in combination with single-distance phase-retrieval algorithms and a dedicated image-processing regime. As demonstrated here, functional CT imaging can be achieved for the assessment of both structural alterations in asthmatic mouse lung tissue and the accumulation pattern of instilled barium-sulfate-labelled macrophages in comparison with healthy controls. Functionalized computed tomography (CT) in combination with labelled cells is virtually non-existent due to the limited sensitivity of X-ray-absorption-based imaging, but would be highly desirable to realise cell tracking studies in entire organisms. In this study we applied in-line free propagation X-ray phase-contrast CT (XPCT) in an allergic asthma mouse model to assess structural changes as well as the biodistribution of barium-labelled macrophages in lung tissue. Alveolar macrophages that were barium-sulfate-loaded and fluorescent-labelled were instilled intratracheally into asthmatic and control mice. Mice were sacrificed after 24 h, lungs were kept in situ, inflated with air and scanned utilizing XPCT at the SYRMEP beamline (Elettra Synchrotron Light Source, Italy). Single-distance phase retrieval was used to generate data sets with ten times greater contrast-to-noise ratio than absorption-based CT (in our setup), thus allowing to depict and quantify structural hallmarks of asthmatic lungs such as reduced air volume, obstruction of airways and increased soft-tissue content. Furthermore, we found a higher concentration as well as a specific accumulation of the barium-labelled macrophages in asthmatic lung tissue. It is believe that XPCT will be beneficial in preclinical asthma research for both the assessment of therapeutic response as well as the analysis of the role of the recruitment of macrophages to inflammatory sites

  5. Visual cortex reactivity in sedated children examined with perfusion MRI (FAIR)

    DEFF Research Database (Denmark)

    Born, A.P.; Rostrup, Egill; Miranda Gimenez-Ricco, Maria Jo; Larsson, H.B.W.; Lou, H.C.

    2002-01-01

    Sleeping and sedated children can respond to visual stimulation with a decrease in blood oxygenation level dependent (BOLD) functional MRI signal response. The contribution of metabolic and hemodynamic parameters to this inverse signal response is incompletely understood. It has been hypothesized...... explanation for the negative BOLD response. Future studies will have to address if this response pattern is a consequence of age or sleep/sedation...

  6. Neural reactivation links unconscious thought to decision-making performance

    OpenAIRE

    Creswell, John David; Bursley, James K.; Ajay B Satpute

    2013-01-01

    Brief periods of unconscious thought (UT) have been shown to improve decision making compared with making an immediate decision (ID). We reveal a neural mechanism for UT in decision making using blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. Participants (N = 33) encoded information on a set of consumer products (e.g. 48 attributes describing four different cars), and we manipulated whether participants (i) consciously thought about this information (conscious thou...

  7. Unstable Prefrontal Response to Emotional Conflict and Activation of Lower Limbic Structures and Brainstem in Remitted Panic Disorder

    OpenAIRE

    Chechko, Natalya; Wehrle, Renate; Erhardt, Angelika; Holsboer, Florian; Czisch, Michael; Sämann, Philipp G

    2009-01-01

    Background The neural mechanisms of panic disorder (PD) are only incompletely understood. Higher sensitivity of patients to unspecific fear cues and similarities to conditioned fear suggest involvement of lower limbic and brainstem structures. We investigated if emotion perception is altered in remitted PD as a trait feature. Methodology/Principal Findings We used blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to study neural and behavioural responses of...

  8. A Component Based Noise Correction Method (CompCor) for BOLD and Perfusion Based fMRI

    OpenAIRE

    Behzadi, Yashar; Restom, Khaled; Liau, Joy; Thomas T. Liu

    2007-01-01

    A component based method (CompCor) for the reduction of noise in both blood oxygenation level dependent (BOLD) and perfusion-based functional magnetic resonance imaging (fMRI) data is presented. In the proposed method, significant principal components are derived from noise regions-of-interest (ROI) in which the time series data are unlikely to be modulated by neural activity. These components are then included as nuisance parameters within general linear models for BOLD and perfusion-based f...

  9. Evaluating Reverse Speech as a Control Task with Language-Related Gamma Activity on Electrocorticography

    OpenAIRE

    Brown, Erik C; Muzik, Otto; Rothermel, Robert; Matsuzaki, Naoyuki; Juhász, Csaba; Shah, Aashit K.; Atkinson, Marie D.; Fuerst, Darren; Mittal, Sandeep; Sood, Sandeep; Diwadkar, Vaibhav A.; Asano, Eishi

    2012-01-01

    Reverse speech has often been used as a control task in brain-mapping studies of language utilizing various non-invasive modalities. The rationale is that reverse speech is comparable to forward speech in terms of auditory characteristics, while omitting the linguistic components. Thus, it may control for non-language auditory functions. This finds some support in fMRI studies indicating that reverse speech resulted in less blood-oxygen-level-dependent (BOLD) signal intensity in perisylvian r...

  10. From fMRI Data To Cognitive Models: Testing the ACT-R Brain Mapping Hypothesis with an Ex-Post Model

    OpenAIRE

    Lenk, Jan Ch.; Möbus, Claus; Özyurt, Jale; Thiel, Christiane M.; Claasen, Arno

    2011-01-01

    Recently, John R. Anderson proposed a correspondence between the modules of his cognitive architecture ACT-R and specific brain regions. This Brain Mapping Hypothesis allows the prediction of Blood-Oxygen-Level Dependent curves for these regions using cognitive models. These predictions may be compared to actual data from functional Magnetic Resonance Imaging experiments. While the Brain Mapping Hypothesis has been tested with very simple tasks mostly from algebraic problem solving, we ...

  11. Évaluation de modèles computationnels de la vision humaine en imagerie par résonance magnétique fonctionnelle

    OpenAIRE

    Eickenberg, Michael

    2015-01-01

    Blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) makes it possible to measure brain activity through blood flow to areas with metabolically active neurons. In this thesis we use these measurements to evaluate the capacity of biologically inspired models of vision coming from computer vision to represent image content in a similar way as the human brain. The main vision models used are convolutional networks.Deep neural networks have made unprecedented progress ...

  12. Alcohol Attenuates Activation in the Bilateral Anterior Insula during an Emotional Processing Task: A Pilot Study †

    OpenAIRE

    Padula, Claudia B.; Simmons, Alan N.; Matthews, Scott C; Robinson, Shannon K.; Tapert, Susan F.; Schuckit, Marc A.; Paulus, Martin P.

    2011-01-01

    Aims: Alcohol acutely reduces agitation and is widely used in social situations, but the neural substrates of emotion processing during its intoxication are not well understood. We examine whether alcohol's social stress dampening effect may be via reduced activity in the cortical systems that subserve awareness of bodily sensations, and are associated with affective distress. Methods: Blood oxygen level-dependent activation was measured through 24 functional magnetic resonance imaging sessio...

  13. Investigation of Anatomical Thalamo-Cortical Connectivity and fMRI Activation in Schizophrenia

    OpenAIRE

    Marenco, Stefano; Stein, Jason L; Savostyanova, Antonina A.; Sambataro, Fabio; Tan, Hao-Yang; Goldman, Aaron L; Verchinski, Beth A.; Barnett, Alan S; Dickinson, Dwight; Apud, José A; Callicott, Joseph H.; Meyer-Lindenberg, Andreas; Weinberger, Daniel R.

    2011-01-01

    The purpose of this study was to examine measures of anatomical connectivity between the thalamus and lateral prefrontal cortex (LPFC) in schizophrenia and to assess their functional implications. We measured thalamocortical connectivity with diffusion tensor imaging (DTI) and probabilistic tractography in 15 patients with schizophrenia and 22 age- and sex-matched controls. The relationship between thalamocortical connectivity and prefrontal cortical blood-oxygenation-level-dependent (BOLD) f...

  14. A statistical approach for segregating cognitive task stages from multivariate fMRI BOLD time series

    OpenAIRE

    Demanuele, Charmaine; Bähner, Florian; Plichta, Michael M; Kirsch, Peter; Tost, Heike; Meyer-Lindenberg, Andreas; Durstewitz, Daniel

    2015-01-01

    Multivariate pattern analysis can reveal new information from neuroimaging data to illuminate human cognition and its disturbances. Here, we develop a methodological approach, based on multivariate statistical/machine learning and time series analysis, to discern cognitive processing stages from functional magnetic resonance imaging (fMRI) blood oxygenation level dependent (BOLD) time series. We apply this method to data recorded from a group of healthy adults whilst performing a virtual real...

  15. Coupling of cerebral blood flow and oxygen metabolism is conserved for chromatic and luminance stimuli in human visual cortex

    OpenAIRE

    Leontiev, Oleg; Buracas, Giedrius T.; Liang, Christine; Ances, Beau M.; Perthen, Joanna E.; Shmuel, Amir; Buxton, Richard B.

    2012-01-01

    The ratio of the changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during brain activation is a critical determinant of the magnitude of the blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI). Cytochrome oxidase (CO), a key component of oxidative metabolism in the mitochondria, is non-uniformly distributed in visual area V1 in distinct blob and interblob regions, suggesting significant spatial variation...

  16. Epilepsy cases: fMRI and MR tractography as qualitative and quantitative tools for proper localization and pre-operative planning

    OpenAIRE

    Ahmed Abdelmoniem Gaber *,Azza M. Sarry El Din**,Eman A.Geneidi, *, Mohamed KhMitkees, *,Wael Abdelhalim Reda, **and Yasser A Abbas

    2012-01-01

    Introduction: Functional MRI is a relatively new noninvasive brain imaging technique that has been used for neuroscience research applications since the early 1990s. This technique relies on the blood oxygenation level dependent (BOLD) effect. Diffusion tensor magnetic resonance imaging (DTI) is a noninvasive technique that can be used to assess the integrity of cerebral tissue. Methods: We evaluated 16 patients with unilateral MTLE. We did MRI for language and memory areas for localization a...

  17. Relation of obesity to neural activation in response to food commercials

    OpenAIRE

    Gearhardt, Ashley N; Yokum, Sonja; Stice, Eric; Harris, Jennifer L.; Brownell, Kelly D.

    2013-01-01

    Adolescents view thousands of food commercials annually, but the neural response to food advertising and its association with obesity is largely unknown. This study is the first to examine how neural response to food commercials differs from other stimuli (e.g. non-food commercials and television show) and to explore how this response may differ by weight status. The blood oxygen level-dependent functional magnetic resonance imaging activation was measured in 30 adolescents ranging from lean ...

  18. Personality modulates the effects of emotional arousal and valence on brain activation

    OpenAIRE

    Kehoe, Elizabeth G.; Toomey, John M.; Balsters, Joshua H.; Bokde, Arun L. W.

    2011-01-01

    The influence of personality on the neural correlates of emotional processing is still not well characterized. We investigated the relationship between extraversion and neuroticism and emotional perception using functional magnetic resonance imaging (fMRI) in a group of 23 young, healthy women. Using a parametric modulation approach, we examined how the blood oxygenation level dependent (BOLD) signal varied with the participants’ ratings of arousal and valence, and whether levels of extravers...

  19. The absolute CBF response to activation is preserved during elevated perfusion: Implications for neurovascular coupling measures

    OpenAIRE

    Whittaker, Joseph R.; Driver, Ian D.; Bright, Molly G.; Murphy, Kevin

    2016-01-01

    Functional magnetic resonance imaging (fMRI) techniques in which the blood oxygenation level dependent (BOLD) and cerebral blood flow (CBF) response to a neural stimulus are measured, can be used to estimate the fractional increase in the cerebral metabolic rate of oxygen consumption (CMRO2) that accompanies evoked neural activity. A measure of neurovascular coupling is obtained from the ratio of fractional CBF and CMRO2 responses, defined as n, with the implicit assumption that relative rath...

  20. Reward-Related Dorsal Striatal Activity Differences between Former and Current Cocaine Dependent Individuals during an Interactive Competitive Game

    OpenAIRE

    Hyatt, Christopher J.; Assaf, Michal; Christine E Muska; Rivkah I Rosen; Thomas, Andre D.; Johnson, Matthew R.; Jennifer L Hylton; Andrews, Melissa M.; Reynolds, Brady A.; Krystal, John H.; Potenza, Marc N.; Pearlson, Godfrey D.

    2012-01-01

    Cocaine addiction is characterized by impulsivity, impaired social relationships, and abnormal mesocorticolimbic reward processing, but their interrelationships relative to stages of cocaine addiction are unclear. We assessed blood-oxygenation-level dependent (BOLD) signal in ventral and dorsal striatum during functional magnetic resonance imaging (fMRI) in current (CCD; n = 30) and former (FCD; n = 28) cocaine dependent subjects as well as healthy control (HC; n = 31) subjects while playing ...

  1. Hemodynamic Traveling Waves in Human Visual Cortex

    OpenAIRE

    Kevin M Aquino; Schira, Mark M.; P A Robinson; Drysdale, Peter M.; Michael Breakspear

    2012-01-01

    Functional MRI (fMRI) experiments rely on precise characterization of the blood oxygen level dependent (BOLD) signal. As the spatial resolution of fMRI reaches the sub-millimeter range, the need for quantitative modelling of spatiotemporal properties of this hemodynamic signal has become pressing. Here, we find that a detailed physiologically-based model of spatiotemporal BOLD responses predicts traveling waves with velocities and spatial ranges in empirically observable ranges. Two measurabl...

  2. Model estimation of cerebral hemodynamics between blood flow and volume changes: a data-based modelling approach

    OpenAIRE

    Wei, H L; Zheng, Y; Pan, Y.; Coca, D.; Li, L M; Mayhew, J.E.W.; S. A. Billings

    2008-01-01

    It is well known that there is a dynamic relationship between cerebral blood flow (CBF) and cerebral blood volume (CBV). With increasing applications of functional magnetic resonance imaging (fMRI), where the blood oxygen level dependent (BOLD) signals are recorded, the understanding and accurate modelling of the hemodynamic relationship between CBF and CBV becomes increasingly important. This study presents an empirical and data-based modelling framework for model identification from CBF and...

  3. Generalized phase contrast:

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than the......Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast...

  4. Compressive Phase Contrast Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-09-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  5. Functional imaging of the lung using a gaseous contrast agent: {sup 3}Helium-magnetic resonance imaging; Funktionelle Bildgebung der Lunge mit gasfoermigem Kontrastmittel: {sup 3}Helium-Magnetresonanztomographie

    Energy Technology Data Exchange (ETDEWEB)

    Gast, K.K.; Heussel, C.P. [Klinik mit Poliklinik fuer Radiologie, Klinikum der Johannes Gutenberg-Univ., Mainz (Germany); Schreiber, W.G. [AG Medizinische Physik, Klinik mit Poliklinik fuer Radiologie, Klinikum der Johannes Gutenberg-Univ., Mainz (Germany); Kauczor, H.U. [Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany)

    2005-05-01

    Current imaging methods of the lung concentrate on morphology as well as on the depiction of the pulmonary parenchyma. The need of an advanced and more subtle imaging technology compared to conventional radiography is met by computed topograhy as the method of choice. Nevertheless, computed tomography yields very limited functional information. This is to be derived from arterial blood gas analysis, spirometry and body plethysmography. These methods, however, lack the scope for regional allocation of any pathology. Magnetic resonance imaging of the lung has been advanced by the use of hyperpolarised {sup 3}Helium as an inhaled gaseous contrast agent. The inhalation of the gas provides functional data by distribution, diffusion and relaxation of its hyperpolarised state. Because anatomical landmarks of the lung can be visualised as well, functional information can be linked with regional information. Furthermore, the method provides high spatial and temporal resolution and lacks the potential side-effects of ionising radiation. Four different modalities have been established: 1. Spin density imaging studies the distribution of gas, normally after a single inhalation of contrast gas in inspiratory breath hold. 2. Dynamic cine imaging studies the distribution of gas with respect to regional time constants of pulmonary gas inflow. 3. Diffusion weighted imaging can exhibit the presence and severity of pulmonary airspace enlargement, as in pulmonary emphysema. 4. Oxygen sensitive imaging displays intrapulmonary oxygen partial pressure and its distribution. Currently, the method is limited by comparably high costs and limited availability. As there have been recent developments which might bring this modality closer to clinical use, this review article will comprise the methodology as well as the current state of the art and standard of knowledge of magnetic resonance imaging of the lung using hyperpolarised {sup 3}Helium. (orig.)

  6. Generalized Phase Contrast

    CERN Document Server

    Glückstad, Jesper

    2009-01-01

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, ...

  7. Compressive Phase Contrast Tomography

    OpenAIRE

    Maia, F. R. N. C.; MacDowell, A.; Marchesini, S.; Padmore, H. A.; Parkinson, D. Y.; PIEN., J.; Schirotzek, A.; Yang, C

    2010-01-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. In- terference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher con- trast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard...

  8. Disconnection and hyper-connectivity underlie reorganization after TBI: A rodent functional connectomic analysis.

    Science.gov (United States)

    Harris, N G; Verley, D R; Gutman, B A; Thompson, P M; Yeh, H J; Brown, J A

    2016-03-01

    While past neuroimaging methods have contributed greatly to our understanding of brain function after traumatic brain injury (TBI), resting state functional MRI (rsfMRI) connectivity methods have more recently provided a far more unbiased approach with which to monitor brain circuitry compared to task-based approaches. However, current knowledge on the physiologic underpinnings of the correlated blood oxygen level dependent signal, and how changes in functional connectivity relate to reorganizational processes that occur following injury is limited. The degree and extent of this relationship remain to be determined in order that rsfMRI methods can be fully adapted for determining the optimal timing and type of rehabilitative interventions that can be used post-TBI to achieve the best outcome. Very few rsfMRI studies exist after experimental TBI and therefore we chose to acquire rsfMRI data before and at 7, 14 and 28 days after experimental TBI using a well-known, clinically-relevant, unilateral controlled cortical impact injury (CCI) adult rat model of TBI. This model was chosen since it has widespread axonal injury, a well-defined time-course of reorganization including spine, dendrite, axonal and cortical map changes, as well as spontaneous recovery of sensorimotor function by 28 d post-injury from which to interpret alterations in functional connectivity. Data were co-registered to a parcellated rat template to generate adjacency matrices for network analysis by graph theory. Making no assumptions about direction of change, we used two-tailed statistical analysis over multiple brain regions in a data-driven approach to access global and regional changes in network topology in order to assess brain connectivity in an unbiased way. Our main hypothesis was that deficits in functional connectivity would become apparent in regions known to be structurally altered or deficient in axonal connectivity in this model. The data show the loss of functional connectivity

  9. Functionalized synchrotron in-line phase-contrast computed tomography: a novel approach for simultaneous quantification of structural alterations and localization of barium-labelled alveolar macrophages within mouse lung samples.

    Science.gov (United States)

    Dullin, Christian; dal Monego, Simeone; Larsson, Emanuel; Mohammadi, Sara; Krenkel, Martin; Garrovo, Chiara; Biffi, Stefania; Lorenzon, Andrea; Markus, Andrea; Napp, Joanna; Salditt, Tim; Accardo, Agostino; Alves, Frauke; Tromba, Giuliana

    2015-01-01

    Functionalized computed tomography (CT) in combination with labelled cells is virtually non-existent due to the limited sensitivity of X-ray-absorption-based imaging, but would be highly desirable to realise cell tracking studies in entire organisms. In this study we applied in-line free propagation X-ray phase-contrast CT (XPCT) in an allergic asthma mouse model to assess structural changes as well as the biodistribution of barium-labelled macrophages in lung tissue. Alveolar macrophages that were barium-sulfate-loaded and fluorescent-labelled were instilled intratracheally into asthmatic and control mice. Mice were sacrificed after 24 h, lungs were kept in situ, inflated with air and scanned utilizing XPCT at the SYRMEP beamline (Elettra Synchrotron Light Source, Italy). Single-distance phase retrieval was used to generate data sets with ten times greater contrast-to-noise ratio than absorption-based CT (in our setup), thus allowing to depict and quantify structural hallmarks of asthmatic lungs such as reduced air volume, obstruction of airways and increased soft-tissue content. Furthermore, we found a higher concentration as well as a specific accumulation of the barium-labelled macrophages in asthmatic lung tissue. It is believe that XPCT will be beneficial in preclinical asthma research for both the assessment of therapeutic response as well as the analysis of the role of the recruitment of macrophages to inflammatory sites. PMID:25537601

  10. Neural responses with happy emotional processing of patients with first-onset major depressive disorder by antidepressant treatment investigated with functional MRI%首发抑郁症患者治疗前后高兴体验的fMRI改变

    Institute of Scientific and Technical Information of China (English)

    孙军; 刘含秋; 冯晓源; 郭琴; 施慎逊

    2009-01-01

    目的:应用功能磁共振(fMRI)技术,探讨首发抑郁症患者药物治疗前后体验高兴表情的脑功能区变化特点.方法:采用3.0 T磁共振,对13例首发抑郁症患者(分别于抗抑郁药物治疗前及治疗8周后)和14例性别、年龄相匹配的正常志愿者进行fMRI检查.运用SPM2分析软件,比较体验高兴表情(与中性表情对照)的脑功能区变化.结果:高兴体验时,治疗前患者组左侧额上、中回背外侧皮层活动性较正常人减低(P<0.001,uncorrected),经过治疗后恢复(P<0.001,uncorrected).结论:高兴体验的fMRI可以作为一项客观评价抗抑郁药物疗效的生物学指标.%Objective:To detect changes of neural response on happy facial expressions in first-onset major depressive disorder (MDD)by antidepressant treatment investigated with functional magnetic resonance imaging (fMRI). Methods:Thirteen patients with first onset MDD and 14 normal age-matched volunteers underwent fMRI and patients underwent scanning twice during an 8-week period. Blood oxygenation level dependent (BOLD) was processed using SPM2 to compare the function of whole brain between the two groups exposure to neutral and positive pictures. Results:Decreased activation of left laterial superior frontal cortex exposure to happy pictures was found in patients compared with control group (P< 0.001, uncorrected). Symptomatic improvement after antidepressant was associated with reversion of left laterial superior frontal cortex (P < 0.001, unconnected). Conclusion: Changes in BOLD of fMRI associated with symptomatic improvement indicate that fMRI may be a useful marker of antidepressant treatment response.

  11. Phase Contrast Imaging

    DEFF Research Database (Denmark)

    1996-01-01

    The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation with a si......The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation...

  12. Compressive Phase Contrast Tomography

    CERN Document Server

    Maia, F R N C; Marchesini, S; Padmore, H A; Parkinson, D Y; Pien, J; Schirotzek, A; Yang, C; 10.1117/12.861946

    2010-01-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. In- terference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher con- trast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  13. Contrast media: future aspects

    Energy Technology Data Exchange (ETDEWEB)

    Weinmann, H.J.; Platzek, J.; Schirmer, H.; Pietsch, H. [Research Labs., Schering AG, Berlin (Germany); Carretero, J.; Harto, J.; Medina, J.; Riefke, B.; Martin, J. [Justesa Imagen SA, Madrid (Spain)

    2005-11-15

    In spite of the dramatic development in CT, there was no major breakthrough in the iodinated contrast media development. New agents based on hybrid between MRI and CT compounds may be a new innovative alternative. This new approach may also open new indications such as radiotherapy. (orig.)

  14. Phonation in Tonal Contrasts

    Science.gov (United States)

    Kuang, Jianjing

    2013-01-01

    Phonation is used in many tonal languages, but how it should be incorporated into tonal systems is not well understood. The purpose of this dissertation thus is to examine the role of phonation in tonal contrasts, and to investigate how phonation and pitch interact in the tonal space. This dissertation presents close studies of tonal contrasts…

  15. Contrast agents for MRI

    International Nuclear Information System (INIS)

    Contrast agents are divided into two categories. The first one is paramagnetic compounds, including lanthanides like gadolinium, which mainly reduce the longitudinal (T1) relaxation property and result in a brighter signal. The second class consists of super-paramagnetic magnetic nanoparticles (SPMNPs) such as iron oxides, which have a strong effect on the transversal (T2) relaxation properties. SPMNPs have the potential to be utilized as excellent probes for magnetic resonance imaging (MRI). For instance, clinically benign iron oxide and engineered ferrite nanoparticles provide a good MRI probing capability for clinical applications. Furthermore, the limited magnetic property and inability to escape from the reticuloendothelial system (RES) of the used nanoparticles impede their further advancement. Therefore, it is necessary to develop the engineered magnetic nanoparticle probes for the next-generation molecular MRI. Considering the importance of MRI in diagnosing diseases, this paper presents an overview of recent scientific achievements in the development of new synthetic SPMNP probes whereby the sensitive and target-specific observation of biological events at the molecular and cellular levels is feasible. - Highlights: • This paper studies the contrast agents for MRI. • Fe―Co alloys and Mn-ferrites exhibit suitable contrast enhancement. • Nonhydrolytic thermal-decomposition synthetic method is suitable to produce MNPs. • This method allows controlling the size, magnetic dopants, magneto-crystalline anisotropy. • The increase in the superparamagnetic size leads to the contrast-enhancement

  16. Nonionic radiographic contrast media

    International Nuclear Information System (INIS)

    The invention deals with nonionic radiographic contrast media. The new media, which are water soluble and have desirable low osmolality properties, are derivates of the 5-amino-2,4,6-triiodine-1,3-benzenecarboxylic acid-unity where the 5-aminonitrogen atom is a part of a 4-, 5- or 6-membered heterocyclic ring

  17. Iodinated contrast media nephrotoxicity

    International Nuclear Information System (INIS)

    In the late seventies, iodinated contrast agents (ICA) were considered to be a major cause of acute iatrogenic renal failure. Over the last decade new contrast agents have been synthesized, nonionic and less hyperosmolar. The incidence of acute renal failure due to ICAs, varies from 3.7 to 70% of cases according to the series, with an average figure of 10.2%. The pathophysiology of ICA nephrotoxicity was mainly studied in laboratory animal models. Three main factors are involved in an inducing ICA-mediated decrease in glomerular filtration rate: reduction of the renal plasma flow, a direct cytotoxic effect on renal tubular cells and erythrocyte alteration leading to intra-renal sludge. Excluding dysglobulinemias with urinary excretion of immunoglobulin light chains, which represent a special case of maximum nephrotoxicity, 4 main risk factors of renal toxicity have been identified in nondiabetic subjects: previous renal failure with serum creatinine levels greater than 140 μmol per liter, extracellular dehydration, age over 60 and use of high doses of ICA and/or repeated ICA injections before serum creatinine levels return to baseline. Preventive measures for avoiding ICA nephrotoxicity are threefold: maintain or restore adequate hydration with saline infusion, stop NSAID treatment several days before ICA administration, and allow a 5 day interval before repeating contrast media injections. New, nonionic and moderately hyperosmolar contrast agents appear to be much less nephrotoxic than conventional ICAs in laboratory animals and in high-risk patients. It is advisable to select such contrast media for investigating high-risk patients. This approach was recently substantiated in well designed, randomized clinical studies which included more than 2 000 patients. (author)

  18. Using High Spatial Resolution to Improve BOLD fMRI Detection at 3T.

    Directory of Open Access Journals (Sweden)

    Juliana Iranpour

    Full Text Available For different functional magnetic resonance imaging experiments using blood oxygenation level-dependent (BOLD contrast, the acquisition of T2*-weighted scans at a high spatial resolution may be advantageous in terms of time-course signal-to-noise ratio and of BOLD sensitivity when the regions are prone to susceptibility artifacts. In this study, we explore this solution by examining how spatial resolution influences activations elicited when appetizing food pictures are viewed. Twenty subjects were imaged at 3 T with two different voxel volumes, 3.4 μl and 27 μl. Despite the diminution of brain coverage, we found that high-resolution acquisition led to a better detection of activations. Though known to suffer to different degrees from susceptibility artifacts, the activations detected by high spatial resolution were notably consistent with those reported in published activation likelihood estimation meta-analyses, corresponding to taste-responsive regions. Furthermore, these regions were found activated bilaterally, in contrast with previous findings. Both the reduction of partial volume effect, which improves BOLD contrast, and the mitigation of susceptibility artifact, which boosts the signal to noise ratio in certain regions, explained the better detection noted with high resolution. The present study provides further evidences that high spatial resolution is a valuable solution for human BOLD fMRI, especially for studying food-related stimuli.

  19. Contrast normalization in colour vision: the effect of luminance contrast on colour contrast detection

    OpenAIRE

    Mullen, Kathy T.; Kim, Yeon Jin; Gheiratmand, Mina

    2014-01-01

    While contrast normalization is well known to occur in luminance vision between overlaid achromatic contrasts, and in colour vision between overlaid colour contrasts, it is unknown whether it transfers between colour and luminance contrast. Here we investigate whether contrast detection in colour vision can be normalized by achromatic contrast, or whether this is a selective process driven only by colour contrast. We use a method of cross-orientation masking, in which colour detection is mask...

  20. Multivoxel Pattern Analysis for fMRI Data: A Review

    Directory of Open Access Journals (Sweden)

    Abdelhak Mahmoudi

    2012-01-01

    Full Text Available Functional magnetic resonance imaging (fMRI exploits blood-oxygen-level-dependent (BOLD contrasts to map neural activity associated with a variety of brain functions including sensory processing, motor control, and cognitive and emotional functions. The general linear model (GLM approach is used to reveal task-related brain areas by searching for linear correlations between the fMRI time course and a reference model. One of the limitations of the GLM approach is the assumption that the covariance across neighbouring voxels is not informative about the cognitive function under examination. Multivoxel pattern analysis (MVPA represents a promising technique that is currently exploited to investigate the information contained in distributed patterns of neural activity to infer the functional role of brain areas and networks. MVPA is considered as a supervised classification problem where a classifier attempts to capture the relationships between spatial pattern of fMRI activity and experimental conditions. In this paper , we review MVPA and describe the mathematical basis of the classification algorithms used for decoding fMRI signals, such as support vector machines (SVMs. In addition, we describe the workflow of processing steps required for MVPA such as feature selection, dimensionality reduction, cross-validation, and classifier performance estimation based on receiver operating characteristic (ROC curves.

  1. Multivoxel Pattern Analysis for fMRI Data: A Review

    Science.gov (United States)

    Takerkart, Sylvain; Regragui, Fakhita; Boussaoud, Driss; Brovelli, Andrea

    2012-01-01

    Functional magnetic resonance imaging (fMRI) exploits blood-oxygen-level-dependent (BOLD) contrasts to map neural activity associated with a variety of brain functions including sensory processing, motor control, and cognitive and emotional functions. The general linear model (GLM) approach is used to reveal task-related brain areas by searching for linear correlations between the fMRI time course and a reference model. One of the limitations of the GLM approach is the assumption that the covariance across neighbouring voxels is not informative about the cognitive function under examination. Multivoxel pattern analysis (MVPA) represents a promising technique that is currently exploited to investigate the information contained in distributed patterns of neural activity to infer the functional role of brain areas and networks. MVPA is considered as a supervised classification problem where a classifier attempts to capture the relationships between spatial pattern of fMRI activity and experimental conditions. In this paper , we review MVPA and describe the mathematical basis of the classification algorithms used for decoding fMRI signals, such as support vector machines (SVMs). In addition, we describe the workflow of processing steps required for MVPA such as feature selection, dimensionality reduction, cross-validation, and classifier performance estimation based on receiver operating characteristic (ROC) curves. PMID:23401720

  2. Polychromatic diffraction contrast tomography

    Energy Technology Data Exchange (ETDEWEB)

    King, A., E-mail: king@synchrotron-soleil.fr [Synchrotron SOLEIL, Gif-sur-Yvette 91192 (France); Reischig, P. [Xnovo Technology ApS, 4600 Køge (Denmark); Department of Materials Science and Engineering, Delft University of Technology, Delft 2628 CD (Netherlands); Adrien, J. [MATEIS, INSA de Lyon, Villeurbanne 69621 (France); Peetermans, S. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Ludwig, W. [MATEIS, INSA de Lyon, Villeurbanne 69621 (France); European Synchrotron Radiation Facility, Grenoble 38043 (France)

    2014-11-15

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented.

  3. Polychromatic diffraction contrast tomography

    International Nuclear Information System (INIS)

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented

  4. Contrastive topics decomposed

    Directory of Open Access Journals (Sweden)

    Michael Wagner

    2012-12-01

    Full Text Available The analysis of contrastive topics introduced in Büring 1997b and further developed in Büring 2003 relies on distinguishing two types of constituents that introduce alternatives: the sentence focus, which is marked by a FOC feature, and the contrastive topic, which is marked by a CT feature. A non-compositional rule of interpretation that refers to these features is used to derive a topic semantic value, a nested set of sets of propositions. This paper presents evidence for a correlation between the restrictive syntax of nested focus operators and the syntax of contrastive topics, a correlation which is unexpected under this analysis. A compositional analysis is proposed that only makes use of the flatter focus semantic values introduced by focus operators. The analysis aims at integrating insights from the original analysis while at the same time capturing the observed syntactic restrictions. http://dx.doi.org/10.3765/sp.5.8 BibTeX info

  5. Contrast medium-induced nephropathy: the pathophysiology

    DEFF Research Database (Denmark)

    Persson, P B; Tepel, Martin

    2006-01-01

    A widespread, rather general, definition of contrast-induced nephropathy (CIN) is an impairment in renal function occurring within 3 days following the intravascular administration of contrast media (CM) and the absence of an alternative aetiology. In spite of the vast clinical importance of CIN...... haemodynamics, regional hypoxia, auto-, and paracrine factors (adenosine, endothelin, reactive oxygen species) to direct cytotoxic effects. Although these potential mediators of CIN will be discussed separately, several factors may act in concert to perturb kidney function after exposure to contrast media. From...... the current knowledge of the mechanisms causing CIN, it is not possible to recommend a certain class of contrast media, except to avoid large doses of CM of the first generation. From a pathophysiological perspective, volume expansion is effective in avoiding CIN, since water permeability of the collecting...

  6. Nephrotoxic effects of iodinated x-ray contrast media in vitro and in vivo : effects on cultured NRK 52-E cells, development of an animal model of impaired renal function and evaluation of biomarkers of nephrotoxicity

    OpenAIRE

    2007-01-01

    Iodinated x-ray contrast media (ICM) are used to improve the visibility of internal structures of the body in an x-ray image due to their ability to attenuate x-rays, providing enhanced contrast between regions of interest and the surrounding tissues. Unfortunately, administration of ICM is associated with adverse side effects, including contrast-induced nephropathy (CIN) which remains one of the most important complications of ICM. The work reported in master’s thesis was aimed at investigat...

  7. Schizophrenia spectrum participants have reduced visual contrast sensitivity to chromatic (red/green and luminance (light/dark stimuli: new insights into information processing, visual channel function and antipsychotic effects

    Directory of Open Access Journals (Sweden)

    Kristin Suzanne Cadenhead

    2013-08-01

    Full Text Available Background: Individuals with schizophrenia spectrum diagnoses have deficient visual information processing as assessed by a variety of paradigms including visual backward masking, motion perception and visual contrast sensitivity (VCS. In the present study, the VCS paradigm was used to investigate potential differences in magnocellular (M versus parvocellular (P channel function that might account for the observed information processing deficits of schizophrenia spectrum patients. Specifically, VCS for near threshold luminance (black/white stimuli is known to be governed primarily by the M channel, while VCS for near threshold chromatic (red/green stimuli is governed by the P channel. Methods: VCS for luminance and chromatic stimuli (counterphase-reversing sinusoidal gratings, 1.22 c/deg, 8.3 Hz was assessed in 53 patients with schizophrenia (including 5 off antipsychotic medication, 22 individuals diagnosed with schizotypal personality disorder and 53 healthy comparison subjects. Results: Schizophrenia spectrum groups demonstrated reduced VCS in both conditions relative to normals, and there was no significant group by condition interaction effect. Post-hoc analyses suggest that it was the patients with schizophrenia on antipsychotic medication as well as SPD participants who accounted for the deficits in the luminance condition. Conclusions: These results demonstrate visual information processing deficits in schizophrenia spectrum populations but do not support the notion of selective abnormalities in the function of subcortical channels as suggested by previous studies. Further work is needed in a longitudinal design to further assess VCS as a vulnerability marker for psychosis as well as the effect of antipsychotic agents on performance in schizophrenia spectrum populations.

  8. Double-contrast enema

    International Nuclear Information System (INIS)

    A solid state digital system (FCR 101) was employed in our comparative evaluation of the image quality of conventional versus digital techniques in the study of colon by means of double-contrast enema. Sixty patients were examined with a single AP view, using digital radiography with 100% radiation dose and progressive 50% and 75% reductions; the radiographs thus obtained were then compared with the corresponding conventional ones. The examined parameters were organ profile and mucosal pattern. Each digital and conventional radiographs was evaluated by 2 independent radiologists and a value is given to each parameter i.e., 1=good, 2=sufficient, 3=insufficient. Upon comparison of the average values obtained for digital and conventional radiographs in optimal conditions and with a dose reduced by 50%, the digital technique was seen to give a more detailed and accurate representation of both low-contrast mucosal pattern and of organ profile. With the dose reduced by 75%, a slight increase was observed in background noise which caused a slight loss in image definition, but this did not reduce image readability with respect to conventional radiographs. To conclude, the digital method with a 50% exposure reduction is to be preferred in the examination of the colon, especially in pediatric radiology; furthermore, since this technique allows better detailing at lower contrast, it is ot be preferred in the study of the pathologic conditions affecting mainly/only the mucosal pattern-e.g., cancer, ulcerative colitis, Crohn's disease, and so on. An exposure dose reduced by 75% may be used for following lesions previously diagnosed and when a less detailed depiction of the mucosal pattern is enough

  9. Contrast media in intussusception

    International Nuclear Information System (INIS)

    Pediatric radiologists in 40 children's hospitals in North America were interviewed to determine their choice of contrast media in the diagnosis and treatment of intussusception. The respondents indicated that barium was utilized in the vast majority of instances. Almost all indicated that they would proceed with barium enema even if there is unequivocal evidence of small bowel obstruction on the plain film examination. In over 14,000 cases of intussusception, there were 55 perforations, an incidence of approximately 1 in 250. The perforations in general were well tolerated, although there was one death. (orig.)

  10. Contrastive discourse studies

    OpenAIRE

    Clyne, Michael

    2009-01-01

    Le discours est un aspect essentiel du langage. Mais cet aspect est lié plus étroitement aux valeurs culturelles. Cet article présente les études contrastives du discours, comment elles ont été menées et les difficultés possibles dans les techniques de collection de données. Une typologie comparative des discours peut se développer au-delà de la typologie grammaticale. Parmi les applications du discours contrastif sont la formation interculturelle et l’enseignement des langues étrangères. ...

  11. Coupling of cerebral blood flow and oxygen metabolism is conserved for chromatic and luminance stimuli in human visual cortex.

    Science.gov (United States)

    Leontiev, Oleg; Buracas, Giedrius T; Liang, Christine; Ances, Beau M; Perthen, Joanna E; Shmuel, Amir; Buxton, Richard B

    2013-03-01

    The ratio of the changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO(2)) during brain activation is a critical determinant of the magnitude of the blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI). Cytochrome oxidase (CO), a key component of oxidative metabolism in the mitochondria, is non-uniformly distributed in visual area V1 in distinct blob and interblob regions, suggesting significant spatial variation in the capacity for oxygen metabolism. The goal of this study was to test whether CBF/CMRO(2) coupling differed when these subpopulations of neurons were preferentially stimulated, using chromatic and luminance stimuli to preferentially stimulate either the blob or interblob regions. A dual-echo spiral arterial spin labeling (ASL) technique was used to measure CBF and BOLD responses simultaneously in 7 healthy human subjects. When the stimulus contrast levels were adjusted to evoke similar CBF responses (mean 65.4% ± 19.0% and 64.6% ± 19.9%, respectively for chromatic and luminance contrast), the BOLD responses were remarkably similar (1.57% ± 0.39% and 1.59% ± 0.35%) for both types of stimuli. We conclude that CBF-CMRO(2) coupling is conserved for the chromatic and luminance stimuli used, suggesting a consistent coupling for blob and inter-blob neuronal populations despite the difference in CO concentration. PMID:23238435

  12. Neural substrates of figurative language during natural speech perception: an fMRI study

    Directory of Open Access Journals (Sweden)

    Arne eNagels

    2013-09-01

    Full Text Available Many figurative expressions are fully conventionalized in everyday speech. Regarding the neural basis of figurative language processing, research has predominantly focused on metaphoric expressions in minimal semantic context. It remains unclear in how far metaphoric expressions during continuous text comprehension activate similar neural networks as isolated metaphors. We therefore investigated the processing of similes (figurative language, e.g. He smokes like a chimney! occurring in a short story.Sixteen healthy, male, native German speakers listened to similes that came about naturally in a short story, while blood-oxygenation-level-dependent (BOLD responses were measured with functional magnetic resonance imaging (fMRI. For the event-related analysis, similes were contrasted with non-figurative control sentences. The stimuli differed with respect to figurativeness, while they were matched for frequency of words, number of syllables, plausibility and comprehensibility.Similes contrasted with control sentences resulted in enhanced BOLD responses in the left inferior (IFG and adjacent middle frontal gyrus. Concrete control sentences as compared to similes activated the bilateral middle temporal gyri as well as the right precuneus and the left middle frontal gyrus.Activation of the left IFG for similes in a short story is consistent with results on single sentence metaphor processing. The findings strengthen the importance of the left inferior frontal region in the processing of abstract figurative speech during continuous, ecologically-valid speech comprehension; the processing of concrete semantic contents goes along with a down-regulation of bilateral temporal regions.

  13. Targeting pain catastrophization in patients with fibromyalgia using virtual reality exposure therapy: a proof-of-concept study.

    Science.gov (United States)

    Morris, Linzette Deidrè; Louw, Quinette Abegail; Grimmer, Karen Anne; Meintjes, Ernesta

    2015-11-01

    [Purpose] Pain catastrophizing is a key predictor of poor compliance to exercises among patients with fibromyalgia syndrome. Alteration of pain catastrophizing in this group is thus warranted. This study aimed to provide proof-of-concept of a novel virtual reality exposure therapy program as treatment for exercise-related pain catastrophizing in patients with fibromyalgia syndrome. [Subjects and Methods] An exploratory, case-controlled study was conducted (fibromyalgia syndrome group and matched control group). Functional magnetic resonance imaging was used to acquire neural correlates. The functional magnetic resonance imaging task consisted of two stimuli: active (exercise activity visuals) and passive (relaxing visuals). Structural images and blood-oxygenation-level-dependent contrasts were acquired for the conditions and compared within subjects/groups and between groups. Statistic images were thresholded using corrected clusters (determined by Z>2.3; level of significance: 0.05). [Results] Thirteen fibromyalgia syndrome subjects and nine healthy matched controls were included. The right inferior frontal gyrus, right middle frontal gyrus, right posterior cerebellum, left thalamus, and left supramarginal gyrus were activated in the fibromyalgia syndrome subjects. [Conclusion] The study results provide preliminary proof indicating that exposing patients with fibromyalgia syndrome to visuals of exercises elicits neurophysiological changes in functional brain areas associated with pain catastrophization and add to the current body of knowledge regarding the possibility of objectively identifying cognitive behavioral strategies like pain catastrophization. PMID:26696719

  14. Intestinal contrasting in abdominal CT

    International Nuclear Information System (INIS)

    In 56 patients undergoing abdominal CT the gastro-intestinal tract was defined by negative contrast instead of the conventional positive contrast from an iodine containing contrast medium. The contrast material was a 2 1/2% mannitol solution and was used for filling the rectum. Filling of the gastro-intestinal tract was of similar quality to that obtained with positve contrast media. The number of artifacts due to high contrast boundaries was slightly greater with the negative contrast than if would have been with positive contrast. Differentiation of the gastro-intestinal tract from other abdominal organs was equally good for both methods. The negative contrast method was poor in diagnosing cystic tumours but proved much better than positive contrast for evaluating the wall of the gastro-intestinal tract. (orig.)

  15. Selective serotonin 5-HT1A receptor biased agonists elicitdistinct brain activation patterns: a pharmacoMRI study.

    Science.gov (United States)

    Becker, G; Bolbos, R; Costes, N; Redouté, J; Newman-Tancredi, A; Zimmer, L

    2016-01-01

    Serotonin 1A (5-HT1A) receptors are involved in several physiological and pathological processes and constitute therefore an important therapeutic target. The recent pharmacological concept of biased agonism asserts that highly selective agonists can preferentially direct receptor signaling to specific intracellular responses, opening the possibility of drugs targeting a receptor subtype in specific brain regions. The present study brings additional support to this concept thanks to functional magnetic resonance imaging (7 Tesla-fMRI) in anaesthetized rats. Three 5-HT1A receptor agonists (8-OH-DPAT, F13714 and F15599) and one 5-HT1A receptor antagonist (MPPF) were compared in terms of influence on the brain blood oxygen level-dependent (BOLD) signal. Our study revealed for the first time contrasting BOLD signal patterns of biased agonists in comparison to a classical agonist and a silent antagonist. By providing functional information on the influence of pharmacological activation of 5-HT1A receptors in specific brain regions, this neuroimaging approach, translatable to the clinic, promises to be useful in exploring the new concept of biased agonism in neuropsychopharmacology. PMID:27211078

  16. Auditory fMRI of Sound Intensity and Loudness for Unilateral Stimulation.

    Science.gov (United States)

    Behler, Oliver; Uppenkamp, Stefan

    2016-01-01

    We report a systematic exploration of the interrelation of sound intensity, ear of entry, individual loudness judgments, and brain activity across hemispheres, using auditory functional magnetic resonance imaging (fMRI). The stimuli employed were 4 kHz-bandpass filtered noise stimuli, presented monaurally to each ear at levels from 37 to 97 dB SPL. One diotic condition and a silence condition were included as control conditions. Normal hearing listeners completed a categorical loudness scaling procedure with similar stimuli before auditory fMRI was performed. The relationship between brain activity, as inferred from blood oxygenation level dependent (BOLD) contrasts, and both sound intensity and loudness estimates were analyzed by means of linear mixed effects models for various anatomically defined regions of interest in the ascending auditory pathway and in the cortex. The results indicate distinct functional differences between midbrain and cortical areas as well as between specific regions within auditory cortex, suggesting a systematic hierarchy in terms of lateralization and the representation of sensory stimulation and perception. PMID:27080657

  17. Color and luminance contrasts attract independent attention.

    Science.gov (United States)

    Morrone, Maria Concetta; Denti, Valentina; Spinelli, Donatella

    2002-07-01

    Paying attention can improve vision in many ways, including some very basic functions such as contrast discrimination, a task that probably reflects very early levels of visual processing. Electrophysiological, psychophysical, and imaging studies on humans as well as single recordings in monkey show that attention can modulate the neuronal response at an early stage of visual processing, probably by acting on the response gain. Here, we measure incremental contrast thresholds for luminance and color stimuli to derive the contrast response of early neural mechanisms and their modulation by attention. We show that, for both cases, attention improves contrast discrimination, probably by multiplicatively increasing the gain of the neuronal response to contrast. However, the effects of attention are highly specific to the visual modality: concurrent attention to a competing luminance, but not chromatic pattern, greatly impedes luminance contrast discrimination; and attending to a competing chromatic, but not luminance, task impedes color contrast discrimination. Thus, the effects of attention are highly modality specific, implying separate attentional resources for different fundamental visual attributes at early stages of visual processing. PMID:12121622

  18. Gain, noise, and contrast sensitivity of linear visual neurons

    Science.gov (United States)

    Watson, Andrew B.

    1990-01-01

    Contrast sensitivity is a measure of the ability of an observer to detect contrast signals of particular spatial and temporal frequencies. A formal definition of contrast sensitivity that can be applied to individual linear visual neurons is derived. A neuron is modeled by a contrast transfer function and its modulus, contrast gain, and by a noise power spectrum. The distributions of neural responses to signal and blank presentations are derived, and from these, a definition of contrast sensitivity is obtained. This formal definition may be used to relate the sensitivities of various populations of neurons, and to relate the sensitivities of neurons to that of the behaving animal.

  19. Contrast media: Biologic effects and clinical application

    International Nuclear Information System (INIS)

    An overview is presented of the recent developments in contrast media and their clinical applications, plus the current state-of-the-art in computerized tomography, digital subtraction angiography, ultrasound and magnetic resonance imaging (MRI). Contents of these volumes include: an in-depth review of the historical development, modern perspectives in structure-function relationships, biologic effects on hemostats, gastrointestinal, cardiovascular systems and drug interactions. Critical and basic issues, including cellular toxicity, mutagenesis, synergism between radiation and contrast agents, mechanisms in contrast-induced reactions, and the management of such reactions in high-risk patients are also presented. Specific applications of paramagnetic compounds in MRI and the recent concept of liposome-encapsulated and particulate suspension of contrast materials in diagnostic imaging are thoroughly discussed

  20. Contrast media: Biologic effects and clinical application

    Energy Technology Data Exchange (ETDEWEB)

    Parvez, Z.; Moncada, R.; Sovak, M.

    1987-01-01

    An overview is presented of the recent developments in contrast media and their clinical applications, plus the current state-of-the-art in computerized tomography, digital subtraction angiography, ultrasound and magnetic resonance imaging (MRI). Contents of these volumes include: an in-depth review of the historical development, modern perspectives in structure-function relationships, biologic effects on hemostats, gastrointestinal, cardiovascular systems and drug interactions. Critical and basic issues, including cellular toxicity, mutagenesis, synergism between radiation and contrast agents, mechanisms in contrast-induced reactions, and the management of such reactions in high-risk patients are also presented. Specific applications of paramagnetic compounds in MRI and the recent concept of liposome-encapsulated and particulate suspension of contrast materials in diagnostic imaging are thoroughly discussed.

  1. A Novel Contrast Enhancement Technique on Palm Bone Images

    OpenAIRE

    Yung-Tsang Chang; Jen-Tse Wang; Wang-Hsai Yang

    2014-01-01

    Contrast enhancement plays a fundamental role in image processing. Many histogram-based techniques are widely used for contrast enhancement of given images, due to their simple function and effectiveness. However, the conventional histogram equalization (HE) methods result in excessive contrast enhancement, which causes natural looking and satisfactory results for a variety of low contrast images. To solve such problems, a novel multi-histogram equalization technique is proposed to enhance th...

  2. Pedagogical Implications of Contrastive Studies

    Science.gov (United States)

    Marton, Waldemar

    1972-01-01

    Pessimism regarding pedagogical applications of contrastive studies, and reasons therefore, are described. Several misunderstandings believed to contribute to this pessimism, and several areas of controversy concerning uses of contrastive studies, are discussed. See FL 508 197 for availability. (RM)

  3. Application of contrast sensitivity in clinical neurology

    NARCIS (Netherlands)

    C. Bulens (Carel)

    1988-01-01

    textabstractThis thesis is devoted to one new diagnostic technique called spatial contrast sensitivity (CS) measurement, to study visual function. This technique provides a much more comprehensive measure of visual efficiency than a standard acuity score. The visibility of objects depends not only o

  4. Blood pressure changes induced by arterial blood withdrawal influence bold signal in anesthesized rats at 7 Tesla: implications for pharmacologic mri.

    Science.gov (United States)

    Kalisch, R; Elbel, G K; Gössl, C; Czisch, M; Auer, D P

    2001-10-01

    Functional magnetic resonance imaging (fMRI) using the blood oxygenation level-dependent (BOLD) contrast is now increasingly applied for measuring drug effects on brain activity. A possible confound in pharmacologic fMRI (phMRI) is that the BOLD signal may be sensitive to systemic cardiovascular or respiratory parameters, which can themselves be modulated by a drug. To assess whether abrupt changes in arterial blood pressure (BP) as may be observed in phMRI experiments influence the BOLD signal, a hemorrhage model was studied in anesthesized rats at 7 T using spin-echo EPI. BP and BOLD signal time courses were found to be significantly correlated (P < 0.01). This effect was detected under the three different anesthetic regimens employed (isoflurane, halothane, and propofol). The regional pattern of BP-BOLD correlations was heterogeneous and may reflect vascular density. In physiological terms, a BOLD decrease during a decrease in BP may result from an increase in mostly venous cerebral blood volume (CBV) as an autoregulatory response to maintain cerebral blood flow (CBF) during decreased perfusion pressure. The observed influence of BP on BOLD may complicate qualitative and quantitative description of drug effects. PMID:11554808

  5. Yearning to yawn: the neural basis of contagious yawning.

    Science.gov (United States)

    Schürmann, Martin; Hesse, Maike D; Stephan, Klaas E; Saarela, Miiamaaria; Zilles, Karl; Hari, Riitta; Fink, Gereon R

    2005-02-15

    Yawning is contagious: Watching another person yawn may trigger us to do the same. Here we studied brain activation with functional magnetic resonance imaging (fMRI) while subjects watched videotaped yawns. Significant increases in the blood oxygen level dependent (BOLD) signal, specific to yawn viewing as contrasted to viewing non-nameable mouth movements, were observed in the right posterior superior temporal sulcus (STS) and bilaterally in the anterior STS, in agreement with the high affinity of STS to social cues. However, no additional yawn-specific activation was observed in Broca's area, the core region of the human mirror-neuron system (MNS) that matches action observation and execution. Thus, activation associated with viewing another person yawn seems to circumvent the essential parts of the MNS, in line with the nature of contagious yawns as automatically released behavioural acts-rather than truly imitated motor patterns that would require detailed action understanding. The subjects' self-reported tendency to yawn covaried negatively with activation of the left periamygdalar region, suggesting a connection between yawn contagiousness and amygdalar activation. PMID:15670705

  6. Vascular Origins of BOLD and CBV fMRI Signals: Statistical Mapping and Histological Sections Compared.

    Science.gov (United States)

    Kennerley, Aneurin J; Mayhew, John E; Redgrave, Peter; Berwick, Jason

    2010-01-01

    Comparison of 3T blood oxygenation level dependent (BOLD) and cerebral blood volume (CBV) activation maps to histological sections enables the spatial discrimination of functional magnetic resonance imaging (fMRI) signal changes into different vascular compartments. We use a standard gradient echo-echo planar imaging technique to measure BOLD signal changes in the somatosensory cortex in response to whisker stimulation. Corresponding changes in CBV were estimated following the infusion of a super-paramagnetic contrast agent. We imaged in a tangential imaging plane that covered the cortical surface. Images were associated with post mortem histological sections showing both the surface vasculature and cytochrome oxidase stained whisker barrel cortex. We found a significant BOLD signal change in the large draining veins which occurred in the absence of a corresponding CBV change. Results suggest that in the venous drainage system, ~3mm distant from the area of activity, there is a robust change in blood oxygen saturation with little or no volume change. CBV changes are localised over the somatosensory barrel cortex and overlying arterial supply, supporting the theory that CBV changes are greater in the arterial than in the venous vasculature. This work investigating BOLD signal and underlying hemodynamics provides more information on the vascular origins of these important neuroimaging signals. PMID:20563253

  7. Visual, Auditory, and Cross Modal Sensory Processing in Adults with Autism: An EEG Power and BOLD fMRI Investigation.

    Science.gov (United States)

    Hames, Elizabeth' C; Murphy, Brandi; Rajmohan, Ravi; Anderson, Ronald C; Baker, Mary; Zupancic, Stephen; O'Boyle, Michael; Richman, David

    2016-01-01

    Electroencephalography (EEG) and blood oxygen level dependent functional magnetic resonance imagining (BOLD fMRI) assessed the neurocorrelates of sensory processing of visual and auditory stimuli in 11 adults with autism (ASD) and 10 neurotypical (NT) controls between the ages of 20-28. We hypothesized that ASD performance on combined audiovisual trials would be less accurate with observable decreased EEG power across frontal, temporal, and occipital channels and decreased BOLD fMRI activity in these same regions; reflecting deficits in key sensory processing areas. Analysis focused on EEG power, BOLD fMRI, and accuracy. Lower EEG beta power and lower left auditory cortex fMRI activity were seen in ASD compared to NT when they were presented with auditory stimuli as demonstrated by contrasting the activity from the second presentation of an auditory stimulus in an all auditory block vs. the second presentation of a visual stimulus in an all visual block (AA2-VV2).We conclude that in ASD, combined audiovisual processing is more similar than unimodal processing to NTs. PMID:27148020

  8. A Sensitivity Analysis of fMRI Balloon Model

    KAUST Repository

    Zayane, Chadia

    2015-04-22

    Functional magnetic resonance imaging (fMRI) allows the mapping of the brain activation through measurements of the Blood Oxygenation Level Dependent (BOLD) contrast. The characterization of the pathway from the input stimulus to the output BOLD signal requires the selection of an adequate hemodynamic model and the satisfaction of some specific conditions while conducting the experiment and calibrating the model. This paper, focuses on the identifiability of the Balloon hemodynamic model. By identifiability, we mean the ability to estimate accurately the model parameters given the input and the output measurement. Previous studies of the Balloon model have somehow added knowledge either by choosing prior distributions for the parameters, freezing some of them, or looking for the solution as a projection on a natural basis of some vector space. In these studies, the identification was generally assessed using event-related paradigms. This paper justifies the reasons behind the need of adding knowledge, choosing certain paradigms, and completing the few existing identifiability studies through a global sensitivity analysis of the Balloon model in the case of blocked design experiment.

  9. Learning Effective Connectivity Network Structure from fMRI Data Based on Artificial Immune Algorithm.

    Science.gov (United States)

    Ji, Junzhong; Liu, Jinduo; Liang, Peipeng; Zhang, Aidong

    2016-01-01

    Many approaches have been designed to extract brain effective connectivity from functional magnetic resonance imaging (fMRI) data. However, few of them can effectively identify the connectivity network structure due to different defects. In this paper, a new algorithm is developed to infer the effective connectivity between different brain regions by combining artificial immune algorithm (AIA) with the Bayes net method, named as AIAEC. In the proposed algorithm, a brain effective connectivity network is mapped onto an antibody, and four immune operators are employed to perform the optimization process of antibodies, including clonal selection operator, crossover operator, mutation operator and suppression operator, and finally gets an antibody with the highest K2 score as the solution. AIAEC is then tested on Smith's simulated datasets, and the effect of the different factors on AIAEC is evaluated, including the node number, session length, as well as the other potential confounding factors of the blood oxygen level dependent (BOLD) signal. It was revealed that, as contrast to other existing methods, AIAEC got the best performance on the majority of the datasets. It was also found that AIAEC could attain a relative better solution under the influence of many factors, although AIAEC was differently affected by the aforementioned factors. AIAEC is thus demonstrated to be an effective method for detecting the brain effective connectivity. PMID:27045295

  10. Visual, Auditory, and Cross Modal Sensory Processing in Adults with Autism:An EEG Power and BOLD fMRI Investigation

    Directory of Open Access Journals (Sweden)

    Elizabeth C Hames

    2016-04-01

    Full Text Available Electroencephalography (EEG and Blood Oxygen Level Dependent Functional Magnetic Resonance Imagining (BOLD fMRI assessed the neurocorrelates of sensory processing of visual and auditory stimuli in 11 adults with autism (ASD and 10 neurotypical (NT controls between the ages of 20-28. We hypothesized that ASD performance on combined audiovisual trials would be less accurate with observable decreased EEG power across frontal, temporal, and occipital channels and decreased BOLD fMRI activity in these same regions; reflecting deficits in key sensory processing areas. Analysis focused on EEG power, BOLD fMRI, and accuracy. Lower EEG beta power and lower left auditory cortex fMRI activity were seen in ASD compared to NT when they were presented with auditory stimuli as demonstrated by contrasting the activity from the second presentation of an auditory stimulus in an all auditory block versus the second presentation of a visual stimulus in an all visual block (AA2­VV2. We conclude that in ASD, combined audiovisual processing is more similar than unimodal processing to NTs.

  11. Visual, Auditory, and Cross Modal Sensory Processing in Adults with Autism: An EEG Power and BOLD fMRI Investigation

    Science.gov (United States)

    Hames, Elizabeth’ C.; Murphy, Brandi; Rajmohan, Ravi; Anderson, Ronald C.; Baker, Mary; Zupancic, Stephen; O’Boyle, Michael; Richman, David

    2016-01-01

    Electroencephalography (EEG) and blood oxygen level dependent functional magnetic resonance imagining (BOLD fMRI) assessed the neurocorrelates of sensory processing of visual and auditory stimuli in 11 adults with autism (ASD) and 10 neurotypical (NT) controls between the ages of 20–28. We hypothesized that ASD performance on combined audiovisual trials would be less accurate with observable decreased EEG power across frontal, temporal, and occipital channels and decreased BOLD fMRI activity in these same regions; reflecting deficits in key sensory processing areas. Analysis focused on EEG power, BOLD fMRI, and accuracy. Lower EEG beta power and lower left auditory cortex fMRI activity were seen in ASD compared to NT when they were presented with auditory stimuli as demonstrated by contrasting the activity from the second presentation of an auditory stimulus in an all auditory block vs. the second presentation of a visual stimulus in an all visual block (AA2-VV2).We conclude that in ASD, combined audiovisual processing is more similar than unimodal processing to NTs. PMID:27148020

  12. BOLD sensitivity and SNR characteristics of parallel imaging-accelerated single-shot multi-echo EPI for fMRI.

    Science.gov (United States)

    Bhavsar, Saurabh; Zvyagintsev, Mikhail; Mathiak, Klaus

    2014-01-01

    Echo-planar imaging (EPI) is a standard procedure in functional magnetic resonance imaging (fMRI) for measuring changes in the blood oxygen level-dependent (BOLD) signal associated with neuronal activity. The images obtained from fMRI with EPI, however, exhibit signal dropouts and geometric distortions. Parallel imaging (PI), due to its short readout, accelerates image acquisition and might reduce dephasing in phase-encoding direction. The concomitant loss of signal-to-noise ratio (SNR) might be compensated through single-shot multi-echo EPI (mEPI). We systematically compared the temporal SNR and BOLD sensitivity of single echoes (TE=15, 45, and 75ms) and contrast-optimized mEPI with and without PI and mEPI-based denoising. Audio-visual stimulation under natural viewing conditions activated distributed neural networks. Heterogeneous SNR, noise gain, and sensitivity maps emerged. In single echoes, SNR and BOLD sensitivity followed the predicted dependency on echo time (TE) and were reduced under PI. However, the combination of echoes with mEPI recovered the quality parameters and increased BOLD signal changes at circumscribed fronto-polar and deep brain structures. We suggest applying PI only in combination with mEPI to reduce imaging artifacts and conserve BOLD sensitivity. PMID:23954488

  13. Carbamazepine reduces memory induced activation of mesial temporal lobe structures: a pharmacological fMRI-study

    Directory of Open Access Journals (Sweden)

    Okujava Michael

    2001-11-01

    Full Text Available Abstract Background and Purpose It is not known whether carbamazepine (CBZ; a drug widely used in neurology and psychiatry influences the blood oxygenation level dependent (BOLD contrast changes induced by neuronal activation and measured by functional MRI (fMRI. We aimed to investigate the influence of CBZ on memory induced activation of the mesial temporal lobes in patients with symptomatic temporal lobe epilepsy (TLE. Material and Methods Twenty-one individual patients with refractory symptomatic TLE with different CBZ serum levels and 20 healthy controls were studied using BOLD fMRI. Mesial temporal lobe (MTL activation was induced by a task that is based on the retrieval of individually familiar visuo-spatial knowledge. The extent of significant MTL fMRI activation was measured and correlated with the CBZ serum level. Results In TLE patients, the extent of significant fMRI activation over both MTL was negatively correlated to the CBZ serum level (Spearman r = -0.654, P Conclusions In TLE patients, carbamazepine reduces the fMRI-detectable changes within the mesial temporal lobes as induced by effortful memory retrieval. FMRI appears to be suitable to study the effects of chronic drug treatment in patients with epilepsy.

  14. Frequently asked questions: iodinated contrast agents.

    Science.gov (United States)

    Bettmann, Michael A

    2004-10-01

    Although iodinated contrast agents are safe and widely used, adverse events occur and questions remain about their use, safety, and interactions. Some questions are easily answered and others still require extensive investigation. For one frequent question--is informed consent necessary before all contrast media injections--the simple answer is no. Another question concerns use of contrast media in patients with prior reactions or allergies. Contrast agents can be safely used in such patients, but special care must be taken to be aware of what the previous reaction was and to be ready to treat any reaction. The protective role of pre-treatment with steroids is well established for minor reactions, but they may not prevent major reactions. It is important to realize that even life-threatening, anaphylactoid reactions are not the result of a true allergy to contrast media. Many questions arise about contrast agent-induced nephropathy. Baseline serum creatinine values should be obtained in patients who are at risk, not all patients. The incidence and natural history of contrast agent-induced nephropathy remain unclear. It occurs only in patients with compromised renal function before contrast agent injection, but even patients with normal serum creatinine levels can have renal dysfunction. Calculated creatinine clearance is a better way to determine risk and to follow this complication. The outcome in almost all patients is benign, with progression to end-stage renal disease being rare. The major risk factors, in addition to renal dysfunction, are long-standing diabetes mellitus, dehydration, and use of other nephrotoxic medications. Recent work in preventing and ameliorating contrast agent-induced nephropathy with N-acetyl cysteine, substitution of an isosmolal nonionic contrast agent, and various hydration regimens has been promising. Another common concern is use of iodinated contrast agents in pregnant or breast-feeding women. In both cases, there is no evidence

  15. The Value of Contrast Echocardiography

    Directory of Open Access Journals (Sweden)

    Shannon C. Treiber

    2016-01-01

    Full Text Available Purpose: There is much evidence-based research proving the effectiveness of contrast echocardiography, but there are still questions and concerns about its specific uses. This study tested the effectiveness of contrast echocardiography in defining the left ventricular endocardial border. Methods: From 30 patients, a total of 60 echocardiograms –– 30 with and 30 without use of contrast –– were retrospectively reviewed by four blinded cardiologists with advanced training in echocardiography. No single cardiologist reviewed contrast and noncontrast images of the same patient. Each set of 30 echocardiograms was then studied for wall-motion scoring. Visualization of left ventricular wall segments and a global visualization confidence level of interpretation were recorded. Results: Of all wall segments (N = 510, 91% were visualized in echocardiograms with use of contrast, whereas 75% of the walls were visualized in echocardiograms without contrast (P < 0.001. Of 30 examinations, 17 contrast echocardiograms were read with high confidence compared to 6 without contrast use (P = 0.004. The number of walls visualized with contrast was increased in 18 patients (60%, whereas noncontrast echocardiograms yielded more visualized walls in 6 patients (20%, P = 0.002. Conclusions: This study demonstrates that contrast is valuable to echocardiographic imaging. Its use should be supported throughout echocardiography clinics and encouraged in certain patients for whom resting and stress echocardiography results without contrast often prove uninterpretable.

  16. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    Energy Technology Data Exchange (ETDEWEB)

    Müller, Mark, E-mail: mark-mueller@ph.tum.de; Yaroshenko, Andre; Velroyen, Astrid; Tapfer, Arne [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Bech, Martin [Medical Radiation Physics, Lund University, Barngatan 2:1, 221 85 Lund (Sweden); Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander [Bruker microCT, Kartuizersweg 3B, B-2550 Kontich (Belgium); Pfeiffer, Franz [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Institut für diagnostische und interventionelle Radiologie, Klinikum rechts der Isar, Technische Universität München, 81675 München (Germany); Institute for Advanced Study, Technische Universität München, 85748 Garching (Germany)

    2015-12-15

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.

  17. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    International Nuclear Information System (INIS)

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed

  18. High-field small animal magnetic resonance oncology studies

    Science.gov (United States)

    Bokacheva, Louisa; Ackerstaff, Ellen; LeKaye, H. Carl; Zakian, Kristen; Koutcher, Jason A.

    2014-01-01

    This review focuses on the applications of high magnetic field magnetic resonance imaging (MRI) and spectroscopy (MRS) to cancer studies in small animals. High-field MRI can provide information about tumor physiology, the microenvironment, metabolism, vascularity and cellularity. Such studies are invaluable for understanding tumor growth and proliferation, response to treatment and drug development. The MR techniques reviewed here include 1H, 31P, chemical exchange saturation transfer imaging and hyperpolarized 13C MRS as well as diffusion-weighted, blood oxygen level dependent contrast imaging and dynamic contrast-enhanced MRI. These methods have been proven effective in animal studies and are highly relevant to human clinical studies.

  19. Reduced-Contrast Approximations for High-Contrast Multiscale Flow Problems

    KAUST Repository

    Chung, Eric T.

    2010-01-01

    In this paper, we study multiscale methods for high-contrast elliptic problems where the media properties change dramatically. The disparity in the media properties (also referred to as high contrast in the paper) introduces an additional scale that needs to be resolved in multiscale simulations. First, we present a construction that uses an integral equation to represent the highcontrast component of the solution. This representation involves solving an integral equation along the interface where the coefficients are discontinuous. The integral representation suggests some multiscale approaches that are discussed in the paper. One of these approaches entails the use of interface functions in addition to multiscale basis functions representing the heterogeneities without high contrast. In this paper, we propose an approximation for the solution of the integral equation using the interface problems in reduced-contrast media. Reduced-contrast media are obtained by lowering the variance of the coefficients. We also propose a similar approach for the solution of the elliptic equation without using an integral representation. This approach is simpler to use in the computations because it does not involve setting up integral equations. The main idea of this approach is to approximate the solution of the high-contrast problem by the solutions of the problems formulated in reduced-contrast media. In this approach, a rapidly converging sequence is proposed where only problems with lower contrast are solved. It was shown that this sequence possesses the convergence rate that is inversely proportional to the reduced contrast. This approximation allows choosing the reduced-contrast problem based on the coarse-mesh size as discussed in this paper. We present a simple application of this approach to homogenization of elliptic equations with high-contrast coefficients. The presented approaches are limited to the cases where there are sharp changes in the contrast (i.e., the high

  20. Effects of computed tomography contrast medium factors on contrast enhancement

    International Nuclear Information System (INIS)

    The various nonionic iodinated contrast media used in contrast computed tomography (CT) studies differ in terms of their composition, characteristics, and iodine concentration (mgI/ml), as well as the volume injected (ml). Compared with ionic iodinated contrast media, nonionic iodinated contrast media are low-osmolar agents, with different agents having different osmotic pressures. Using a custom-made phantom incorporating a semipermeable membrane, the osmotic flow rate (hounsfield unit (HU)/s) could easily be measured based on the observed increase in CT numbers, and the relationship between the osmotic pressure and the osmotic flow rate could be obtained (r2=0.84). In addition, taking the effects of patient size into consideration, the levels of contrast enhancement in the abdominal aorta (AA) and inferior vena cava (IVC) were compared among four types of CT contrast medium. The results showed differences in contrast enhancement in the IVC during the equilibrium phase depending on the type of contrast medium used. It was found that the factors responsible for the differences observed in enhancement in the IVC were the osmotic flow rate and the volume of the blood flow pathways in the circulatory system. It is therefore considered that the reproducibility of contrast enhancement is likely to be reduced in the examination of parenchymal organs, in which scanning must be performed during the equilibrium phase, even if the amount of iodine injected per unit body weight (mgI/kg) is maintained at a specified level. (author)

  1. The differing roles of comparison and contrast in children's categorization.

    Science.gov (United States)

    Namy, Laura L; Clepper, Lauren E

    2010-11-01

    Comparison of perceptually similar exemplars from an object category encourages children to overlook compelling perceptual similarities and use relational and functional properties more relevant for taxonomic categorization. This article investigates whether showing children a contrasting object that is perceptually similar but out of kind serves the same function as comparison in heightening children's attention to taxonomically relevant features. In this study, 4-year-olds completed a forced-choice categorization task in which they viewed exemplars from a target category and then selected among (a) a perceptually similar out-of-kind object, (b) a category member that differed perceptually from the exemplars, and (c) a thematically related object. Children were assigned to one of four conditions: No-Compare/No-Contrast, Compare/No-Contrast, No-Compare/Contrast, or Compare/Contrast. As in previous work, comparison increased the frequency of category responses, but there was no effect of contrast on categorization. However, only those in the Compare/Contrast condition displayed consistently taxonomic patterns of responding. Follow-up studies revealed that the effect of comparison plus contrast was evident only when comparison preceded, rather than followed, contrast information and that the value added by providing contrastive information is not attributable to the perceptual similarity between the category exemplars and the contrast object. Comparison and contrast make differing contributions to children's categorization. PMID:20609449

  2. The Effects of Auditory Contrast Tuning upon Speech Intelligibility

    Science.gov (United States)

    Killian, Nathan J.; Watkins, Paul V.; Davidson, Lisa S.; Barbour, Dennis L.

    2016-01-01

    We have previously identified neurons tuned to spectral contrast of wideband sounds in auditory cortex of awake marmoset monkeys. Because additive noise alters the spectral contrast of speech, contrast-tuned neurons, if present in human auditory cortex, may aid in extracting speech from noise. Given that this cortical function may be underdeveloped in individuals with sensorineural hearing loss, incorporating biologically-inspired algorithms into external signal processing devices could provide speech enhancement benefits to cochlear implantees. In this study we first constructed a computational signal processing algorithm to mimic auditory cortex contrast tuning. We then manipulated the shape of contrast channels and evaluated the intelligibility of reconstructed noisy speech using a metric to predict cochlear implant user perception. Candidate speech enhancement strategies were then tested in cochlear implantees with a hearing-in-noise test. Accentuation of intermediate contrast values or all contrast values improved computed intelligibility. Cochlear implant subjects showed significant improvement in noisy speech intelligibility with a contrast shaping procedure.

  3. Studies on levels and interactions of contact activation factors in plasma. A basis for the elucidation of their function in anaphylactoid reactions to dextran and to radiographic contrast media

    Energy Technology Data Exchange (ETDEWEB)

    Hoem, N.O.

    1992-12-31

    Summary of findings and conclusions of relevance: A part of the thesis concerns the effects of intravenous contrast media on the blood pressure and on factors of the contact activation system in the rat. The intravenous injection of dextran induced a profound and lasting fall in blood pressure, preceded by significant lowering in prekallikrein and activation factor 12. The non-ionic radiographic contrast media iohexol caused no significant alterations, neither in blood pressure, nor in levels of contact factors, whereas the ionic radiographic contrast media iodipamide had effects. It induced a rapid, but short-lived, fall in blood pressure and a small, but statistically significant reduction in the measurable amount of activation factor 12a. An observation of significance was that pretreatment of the rats with iodipamide almost blocked the dextran-induced blood pressure fall, and abolished the reduction in prekallikrein and activation factor 12a. It is concluded that the ionic radiographic contrast media used was capable of blocking dextran shock in the rat by preventing an activation of contact activation system. 130 refs., 5 figs.

  4. Multimodality functional imaging of spontaneous canine tumors using 64CU-ATSM and 18FDG PET/CT and dynamic contrast enhanced perfusion CT

    DEFF Research Database (Denmark)

    Hansen, Anders E; Kristensen, Annemarie T; Law, Ian;

    2012-01-01

    To compare the distribution and uptake of the hypoxia tracer (64)Cu-diacetyl-bis(N(4)-methylthiosemicarbazone) ((64)Cu-ATSM) PET/CT, FDG PET/CT and dynamic contrast enhanced perfusion CT (DCE-pCT) in spontaneous canine tumors. In addition (64)Cu-ATSM distribution over time was evaluated....

  5. [Allergy to radiographic contrast media].

    Science.gov (United States)

    Vionnet, Julien; Petitpierre, Stéphanie; Fumeaux, Alexandre; Meuli, Reto; Spertini, Francois; Comte, Denis

    2013-04-17

    Allergy to radiographic contrast media Hypersensitivity reactions to radio-contrast media are common in the daily practice. These products are responsible for immediate ( 1 hour after administration) hypersensitivity reactions. A diagnostic work-up by an allergologist with skin tests and in some cases provocation tests is of value in reducing the risk of recurrent hypersensitivity reactions to iodinated contrast media. A careful selection of the patients is required because the incidence of breakthrough reactions is still concerning, even with proper premedication. Practical recommendations are presented in this article. For gadolinium-based contrast agents, data in the literature is not sufficient for suggesting guidelines. PMID:23667970

  6. Contrast-enhanced MRI of the lung

    Energy Technology Data Exchange (ETDEWEB)

    Kauczor, Hans-Ulrich E-mail: kauczor@radiologie.klinik.uni-mainz.de; Kreitner, Karl-Friedrich

    2000-06-01

    The lung has long been neglected by MR imaging. This is due to unique intrinsic difficulties: (1) signal loss due to cardiac pulsation and respiration; (2) susceptibility artifacts caused by multiple air-tissue interfaces; (3) low proton density. There are many MR strategies to overcome these problems. They consist of breath-hold imaging, respiratory and cardiac gating procedures, use of short repetition and echo times, increase of the relaxivity of existing spins by administration of intravenous contrast agents, and enrichment of spin density by hyperpolarized noble gases or oxygen. Improvements in scanner performance and frequent use of contrast media have increased the interest in MR imaging and MR angiography of the lung. They can be used on a routine basis for the following indications: characterization of pulmonary nodules, staging of bronchogenic carcinoma, in particular assessment of chest wall invasion; evaluation of inflammatory activity in interstitial lung disease; acute pulmonary embolism, chronic thromboembolic pulmonary hypertension, vascular involvement in malignant disease; vascular abnormalities. Future perspectives include perfusion imaging using extracellular or intravascular (blood pool) contrast agents and ventilation imaging using inhalation of hyperpolarized noble gases, of paramagnetic oxygen or of aerosolized contrast agents. These techniques represent new approaches to functional lung imaging. The combination of visualization of morphology and functional assessment of ventilation and perfusion is unequalled by any other technique.

  7. 帕金森病静息态脑功能MRI研究%A resting-state functional MRI study in Parkinson's disease

    Institute of Scientific and Technical Information of China (English)

    彭帅; 陈敏; 李春媚; 马欣昕; 娄宝辉; 罗晓捷; 王蕊; 苏闻

    2014-01-01

    Objectives:Blood-oxygen-level dependent functional magnetic resonance imaging (BOLD-fMRI) was used to investigate the resting-state brain functional abnormalities in patients with Parkinson's disease (PD). Materials and Methods:Totally 68 clinically diagnosed PD patients with at least 12 hours withdrawal time and age-and gender-matched 36 normal controls (NC) were included to take clinical scale evaluation and resting-state BOLD-fMRI examination. All subjects were scanned with Philips 3.0 Tesla MRI system. The fMRI data were processed and analysed by DPARSF V2.0 soft and REST V1.8 soft. Two-sample t-test was used to examine the mALFF differences between PD group and NC group. Results: Compared to NC group, PD group had significantly decreased mALFF values in extensive brain regions including bilateral SMA, middle and posterior cingulate cortex, precuneus, hippocampus, parahippocampal gyrus, lateral globus pallidus, dorsal thalamus, anterior lobe of cerebellum, and right local primary motor cortex, insular cortex, caudate nucleus, putamen, posterior lobe of cerebellum as well as increased mALFF values in several brain regions including extensive cortex of bilateral anterior frontal, parietal and temporal lobe, and left occipital primary visual cortex (P<0.05, AlphaSim corrected). Conclusions:Resting-state brain functional abnormalities of PD patients are extensive. The neuronal activity decreases mainly in several areas including motor regulation related brain regions, default mode network and limbic system, and increases mainly in extensive cortex of anterior frontal, parietal, temporal lobe and primary visual cortex.%目的:应用血氧水平依赖的功能MRI(BOLD-fMRI),探索帕金森病(PD)患者静息态脑功能可能存在的异常。材料与方法对68例PD患者和36例健康志愿者进行静息态BOLD-fMRI检查。分析PD组与正常对照组标准化脑功能低频振荡幅度(mALFF)的差异。结果与正常对照组比较,PD组在双侧辅

  8. Contrast-enhanced endoscopic ultrasonography

    DEFF Research Database (Denmark)

    Reddy, Nischita K; Ioncică, Ana Maria; Săftoiu, Adrian;

    2011-01-01

    sonography to depict tumor neovascularization can be increased by contrast agents. Contrast-enhanced harmonic imaging is a useful aid in identifying the tumor vasculature and studying pancreatic microperfusion. In the future, these techniques could potentially be used to quantify tumor perfusion, to assess......Contrast agents are increasingly being used to characterize the vasculature in an organ of interest, to better delineate benign from malignant pathology and to aid in staging and directing therapeutic procedures. We review the mechanisms of action of first, second and third generation contrast...... agents and their use in various endoscopic procedures in the gastrointestinal tract. Various applications of contrast-enhanced endoscopic ultrasonography include differentiating benign from malignant mediastinal lymphadenopathy, assessment of depth of invasion of esophageal, gastric and gall bladder...

  9. Working memory in volunteers and schizophrenics using BOLD fMRI

    International Nuclear Information System (INIS)

    Functional magnetic resonance imaging uses the blood oxygen level-dependent effect (BOLD MRI) for noninvasive display of cerebral correlatives of cognitive function. The importance for the understanding of physiological and pathological processes is demonstrated by investigations of working memory in schizophrenics and healthy controls. Working memory is involved in processing rather than storage of information and therefore is linked to complex processes such as learning and problem solving. In schizophrenic psychosis, these functions are clearly restricted. Training effects in the working memory task follow an inverse U-shape function, suggesting that cerebral activation reaches a peak before economics of the brain find a more efficient method and activation decreases. (orig.)

  10. Contrast-enhanced peripheral MRA. Technique and contrast agents

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Yousef W. [Dept. of Radiology, Copenhagen Univ. Hospital Bispebjerg, Bispebjerg (Denmark)], e-mail: ywnielsen@gmail.com; Thomsen, Henrik S. [Dept. of Diagnostic Radiology, Copenhagen Univ. Hospital Herlev, Herlev (Denmark)

    2012-09-15

    In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic field strength of the MRI system, receiver coil configuration, use of parallel imaging, contrast bolus timing technique, and k-space filling strategies. Furthermore, it is possible to optimize peripheral CE-MRA using venous compression techniques, hybrid scan protocols, time-resolved imaging, and steady-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Using optimized technique and a stable MRI contrast agent, peripheral CE-MRA is a safe procedure with diagnostic accuracy close to that of conventional catheter X

  11. Contrast-enhanced peripheral MRA. Technique and contrast agents

    International Nuclear Information System (INIS)

    In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic field strength of the MRI system, receiver coil configuration, use of parallel imaging, contrast bolus timing technique, and k-space filling strategies. Furthermore, it is possible to optimize peripheral CE-MRA using venous compression techniques, hybrid scan protocols, time-resolved imaging, and steady-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Using optimized technique and a stable MRI contrast agent, peripheral CE-MRA is a safe procedure with diagnostic accuracy close to that of conventional catheter X

  12. Contrastive marking in French dialogue: Why and how.

    OpenAIRE

    Vion, Monique; Colas, Annie

    1995-01-01

    This experiment studies French-speaking adults' preferences for prosodic marking (focal accent) or morphosyntactic marking (clefting) to express information contrasts in dialogue. Our goal is to determine what syntactic and conceptual factors might contribute to these preferences, by examining for the former, the grammatical function of the item bearing the contrastive mark (subject Vs complement), and for the latter, the size of the class to which the contrasted item belongs (two members Vs ...

  13. Aberrant spontaneous low-frequency brain activity in male patients with severe obstructive sleep apnea revealed by resting-state functional MRI

    Directory of Open Access Journals (Sweden)

    Li HJ

    2015-01-01

    , OSAs showed significant lower-ALFF areas in the cluster of the right precuneus and bilateral posterior cingulate gyrus, as well as a higher-ALFF area in the left inferior frontal gyrus. The area under the curve values of the lower- and higher-ALFF areas were 0.90 and 0.93, respectively. Further diagnostic analysis exhibited that the sensibility and specificity of the two clusters were 80% and 92%, respectively. The mean signal value of the lower-ALFF cluster displayed significant positive correlations with lowest oxygen saturation (r=0.447, P=0.025 and MoCA score (r=0.405, P=0.045.Conclusion: OSAs may involve in a dysfunction in the default mode network and an adaptive compensatory response in the frontal lobe, which reflect the underlying pathophysiology of cognitive impairment. Keywords: obstructive sleep apnea, amplitude of low-frequency fluctuation, functional magnetic resonance imaging, resting state, spontaneous activity, blood oxygen-level-dependent

  14. Ultrasound despeckling for contrast enhancement.

    Science.gov (United States)

    Tay, Peter C; Garson, Christopher D; Acton, Scott T; Hossack, John A

    2010-07-01

    Images produced by ultrasound systems are adversely hampered by a stochastic process known as speckle. A despeckling method based upon removing outlier is proposed. The method is developed to contrast enhance B-mode ultrasound images. The contrast enhancement is with respect to decreasing pixel variations in homogeneous regions while maintaining or improving differences in mean values of distinct regions. A comparison of the proposed despeckling filter is compared with the other well known despeckling filters. The evaluations of despeckling performance are based upon improvements to contrast enhancement, structural similarity, and segmentation results on a Field II simulated image and actual B-mode cardiac ultrasound images captured in vivo. PMID:20227984

  15. The Generalised Phase Contrast Method

    DEFF Research Database (Denmark)

    Glückstad, Jesper

    An analytic framework and a complete description for the design and optimisation of on-axis centred spatially filtering common path systems are presented. The Generalised Phase Contrast method is derived and introduced as the common denominator for these systems basically extending Zernike......’s original phase contrast scheme into a much wider range of operation and application. It is demonstrated that the Generalised Phase Contrast method can be successfully applied to the interpretation and subsequent optimisation of a number of different, commonly applied spatially filtering architectures...... designs and parameter settings. Finally, a number of original applications facilitated by the parallel light-beam encoding of the Generalised Phase Contrast method are briefly outlined. These include among others, wavefront sensing and generation, advanced usercontrolled optical micro...

  16. Contrast-enhanced endoscopic ultrasonography

    DEFF Research Database (Denmark)

    Reddy, Nischita K; Ioncica, Ana Maria; Saftoiu, Adrian;

    2011-01-01

    Contrast agents are increasingly being used to characterize the vasculature in an organ of interest, to better delineate benign from malignant pathology and to aid in staging and directing therapeutic procedures. We review the mechanisms of action of first, second and third generation contrast...... agents and their use in various endoscopic procedures in the gastrointestinal tract. Various applications of contrast-enhanced endoscopic ultrasonography include differentiating benign from malignant mediastinal lymphadenopathy, assessment of depth of invasion of esophageal, gastric and gall bladder...... cancers and visualization of the portal venous system and esophageal varices. In addition, contrast agents can be used to differentiate pancreatic lesions. The use of color Doppler further increases the ability to diagnose and differentiate various pancreatic malignancies. The sensitivity of power Doppler...

  17. Small intestine contrast injection (image)

    Science.gov (United States)

    ... and throat, through the stomach into the small intestine. When in place, contrast dye is introduced and ... means of demonstrating whether or not the small intestine is normal when abnormality is suspected.

  18. Contrast-enhanced peripheral MRA

    DEFF Research Database (Denmark)

    Nielsen, Yousef W; Thomsen, Henrik S

    2012-01-01

    In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast......-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged...... agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic...

  19. Psychological and physiological impact of 36 h total sleep deprivation on the executive function of the brain%睡眠剥夺影响脑执行功能的心理生理研究

    Institute of Scientific and Technical Information of China (English)

    邵永聪; 叶恩茂; 王富贵; 毕国华; 靳霄; 杨征

    2011-01-01

    目的 研究36 h完全睡眠剥夺(total sleep deprivation,TSD)对脑执行控制功能的影响.方法试验采用自身前后对照设计,对14名健康男性进行Go/Nogo测验,同时进行事件相关电位(event-related potentials,ERP)记录及功能性磁共振成像(functional magnetic resonance imaging,fMRI)扫描.结果 36 h睡眠剥夺后受试者的正确击中率明显下降,错误反应率显著增高.ERP结果显示:(1)TSD使Nogo-N2和Nogo-P3波幅下降,潜伏期延长;(2)经过8 h的恢复性睡眠,Nogo-N2和Nogo-P3的波幅与TSD后相比有所恢复,但未恢复至基线水平.fMRI 结果显示,SD后前扣带回皮质(anterior cingulate cortex,ACC)活动降低,前额叶皮质活动明显增强.结论 36 h睡眠剥夺导致脑执行控制功能的显著下降,前额叶皮质出现功能代偿是维持机体认知作业的重要特征.8 h恢复性睡眠可以使脑执行控制功能得到部分恢复,但并不能恢复至基线水平.%Objective To study the impact of 36 h total sleep deprivation( TSD ) on the executive control function of the brain. Methods Healthy young men ( n = 14 ) undergoing the visual Go/Nogo task before and after 36 h sleep deprivation were studied with event related potentials ( ERP ) and functional magnetic resonance imaging ( fMRI ). Results The hit rate of Go/Nogo task decreased and the false alarm rate increased after 36 h sleep deprivation. TSD induced decreased the amplitude, but enhanced the latency of Nogo-N2 and Nogo-P3 on Fz and Nogo-P3 on Cz electrode. The latency of the recovery value of Nogo-N2 and Nogo-P3 was statistically significant compared to the baseline. TSD-induced positive and negative blood oxygenation level-dependent ( BOLD ) signals were compared with those after a normal night's sleep ( NORM ). The activated areas with positive BOLD signals included the superior prefrontal cortex and inferior prefrontal cortex while those with negative BOLD signal were in the anterior cingulate cortex ( ACC ) and

  20. Ultrasound Despeckling for Contrast Enhancement

    OpenAIRE

    Tay, Peter C.; Garson, Christopher D.; Acton, Scott T.; Hossack, John A.

    2010-01-01

    Images produced by ultrasound systems are adversely hampered by a stochastic process known as speckle. A despeckling method based upon removing outlier is proposed. The method is developed to contrast enhance B-mode ultrasound images. The contrast enhancement is with respect to decreasing pixel variations in homogeneous regions while maintaining or improving differences in mean values of distinct regions. A comparison of the proposed despeckling filter is compared with the other well known de...

  1. Contrast-enhanced endoscopic ultrasonography

    Institute of Scientific and Technical Information of China (English)

    Nischita K Reddy; Ana Maria Ioncic(a); Adrian S(a)ftoiu; Peter Vilmann; Manoop S Bhutani

    2011-01-01

    Contrast agents are increasingly being used to characterize the vasculature in an organ of interest,to better delineate benign from malignant pathology and to aid in staging and directing therapeutic procedures.We review the mechanisms of action of first,second and third generation contrast agents and their use in various endoscopic procedures in the gastrointestinal tract.Various applications of contrast-enhanced endoscopic ultrasonography include differentiating benign from malignant mediastinal lymphadenopathy,assessment of depth of invasion of esophageal,gastric and gall bladder cancers and visualization of the portal venous system and esophageal varices.In addition,contrast agents can be used to differentiate pancreatic lesions.The use of color Doppler further increases the ability to diagnose and differentiate various pancreatic malignancies.The sensitivity of power Doppler sonography to depict tumor neovascularization can be increased by contrast agents.Contrast-enhanced harmonic imaging is a useful aid in identifying the tumor vasculature and studying pancreatic microperfusion.In the future,these techniques could potentially be used to quantify tumor perfusion,to assess and monitor the efficacy of antiangiogenic agents,to assist targeted drug delivery and allow molecular imaging.

  2. Lexical representation of novel L2 contrasts

    Science.gov (United States)

    Hayes-Harb, Rachel; Masuda, Kyoko

    2005-04-01

    There is much interest among psychologists and linguists in the influence of the native language sound system on the acquisition of second languages (Best, 1995; Flege, 1995). Most studies of second language (L2) speech focus on how learners perceive and produce L2 sounds, but we know of only two that have considered how novel sound contrasts are encoded in learners' lexical representations of L2 words (Pallier et al., 2001; Ota et al., 2002). In this study we investigated how native speakers of English encode Japanese consonant quantity contrasts in their developing Japanese lexicons at different stages of acquisition (Japanese contrasts singleton versus geminate consonants but English does not). Monolingual English speakers, native English speakers learning Japanese for one year, and native speakers of Japanese were taught a set of Japanese nonwords containing singleton and geminate consonants. Subjects then performed memory tasks eliciting perception and production data to determine whether they encoded the Japanese consonant quantity contrast lexically. Overall accuracy in these tasks was a function of Japanese language experience, and acoustic analysis of the production data revealed non-native-like patterns of differentiation of singleton and geminate consonants among the L2 learners of Japanese. Implications for theories of L2 speech are discussed.

  3. Stylistique(s) contrastive(s) du discours scientifique

    OpenAIRE

    Michel PETIT

    2012-01-01

    On postule que la stylistique a un rôle important à jouer dans l'étude du discours scientifique. Après avoir examiné les facteurs de diversité du discours scientifique et le statut de l'anglais scientifique, on s'intéresse à la question du style scientifique, notamment en termes d'expérience commune. On est enfin conduit, en étudiant les approches contrastives, à envisager une stylistique véritablement contrastive propre à rendre compte des spécificités du discours scientifique.

  4. Covert neurofeedback without awareness shapes cortical network spontaneous connectivity.

    Science.gov (United States)

    Ramot, Michal; Grossman, Shany; Friedman, Doron; Malach, Rafael

    2016-04-26

    Recent advances in blood oxygen level-dependent-functional MRI (BOLD-fMRI)-based neurofeedback reveal that participants can modulate neuronal properties. However, it is unknown whether such training effects can be introduced in the absence of participants' awareness that they are being trained. Here, we show unconscious neurofeedback training, which consequently produced changes in functional connectivity, introduced in participants who received positive and negative rewards that were covertly coupled to activity in two category-selective visual cortex regions. The results indicate that brain networks can be modified even in the complete absence of intention and awareness of the learning situation, raising intriguing possibilities for clinical interventions. PMID:27071084

  5. Resting-state fMRI: A window into human brain plasticity

    OpenAIRE

    Guerra-Carrillo, B; Mackey, AP; Bunge, SA

    2014-01-01

    © The Author(s) 2014. Although brain plasticity is greatest in the first few years of life, the brain continues to be shaped by experience throughout adulthood. Advances in fMRI have enabled us to examine the plasticity of large-scale networks using blood oxygen level-dependent (BOLD) correlations measured at rest. Resting-state functional connectivity analysis makes it possible to measure task-independent changes in brain function and therefore could provide unique insights into experience-d...

  6. Tissue-specific MR contrast agents

    International Nuclear Information System (INIS)

    The purpose of this review is to outline recent trends in contrast agent development for magnetic resonance imaging. Up to now, small molecular weight gadolinium chelates are the workhorse in contrast enhanced MRI. These first generation MR contrast agents distribute into the intravascular and interstitial space, thus allowing the evaluation of physiological parameters, such as the status or existence of the blood-brain-barrier or the renal function. Shortly after the first clinical use of paramagnetic metallochelates in 1983, compounds were suggested for liver imaging and enhancing a cardiac infarct. Meanwhile, liver specific contrast agents based on gadolinium, manganese or iron become reality. Dedicated blood pool agents will be available within the next years. These gadolinium or iron agents will be beneficial for longer lasting MRA procedures, such as cardiac imaging. Contrast enhanced lymphography after interstitial or intravenous injection will be another major step forward in diagnostic imaging. Metastatic involvement will be seen either after the injection of ultrasmall superparamagnetic iron oxides or dedicated gadolinium chelates. The accumulation of both compound classes is triggered by an uptake into macrophages. It is likely that similar agents will augment MRI of atheriosclerotic plaques, a systemic inflammatory disease of the arterial wall. Thrombus-specific agents based on small gadolinium labeled peptides are on the horizon. It is very obvious that the future of cardiovascular MRI will benefit from the development of new paramagnetic and superparamagnetic substances. The expectations for new tumor-, pathology- or receptor-specific agents are high. However, is not likely that such a compound will be available for daily routine MRI within the next decade

  7. Nonpharmacological Strategies to Prevent Contrast-Induced Acute Kidney Injury

    Directory of Open Access Journals (Sweden)

    Paweena Susantitaphong

    2014-01-01

    Full Text Available Contrast-induced AKI (CI-AKI has been one of the leading causes for hospital-acquired AKI and is associated with independent risk for adverse clinical outcomes including morbidity and mortality. The aim of this review is to provide a brief summary of the studies that focus on nonpharmacological strategies to prevent CI-AKI, including routine identification of at-risk patients, use of appropriate hydration regimens, withdrawal of nephrotoxic drugs, selection of low-osmolar contrast media or isoosmolar contrast media, and using the minimum volume of contrast media as possible. There is no need to schedule dialysis in relation to injection of contrast media or injection of contrast agent in relation to dialysis program. Hemodialysis cannot protect the poorly functioning kidney against CI-AKI.

  8. Neurotoxicity of iodinated radiological contrast media

    International Nuclear Information System (INIS)

    We studied during the last ten years the neurotoxicity of artificial iodinated contrast media, with prospective clinical and experimental protocols. The experimental investigation in animals aimed to understand the relationship between the intracarotid injection, the subarachnoid application and the integrity of the blood-brain barrier function. The electro physiologic disturbances and the morphologic observation of pial circulation support the evidence that iodinated artificial contrast media induces significant alterations in brain metabolism and in the autoregulation of the blood flow of the encephalon. Even if many of such phenomena may not be apparent at the clinical level, we supposed that they are always present and that their clinical exteriorization is prevented by the immediate and effective action of homeostatic mechanisms. (author)

  9. Enhanced ferrite nanoparticles as MRI contrast agents

    International Nuclear Information System (INIS)

    Enhanced ferrite nanoparticles are a new class of contrast agents for magnetic resonance imaging (MRI). The enhanced ferrites are synthesized by reverse micelles technique to form iron core and oxide or ferrite shell preventing further oxidation of the nanoparticles. The nanoparticles are further functionalized using dopamine and PEG-600 to increase the solubility of the high magnetic moment nanoparticles. 1H relaxation measurements of aqueous solutions of the nanoparticles were conducted at 2.4 T. The relaxivities r 1 and r 2, representing the slopes of these curves, are 7.19 and 9.96 s-1 mM-1, respectively. These values should be compared with relaxivities of 4-5 s-1 mM-1 corresponding to commonly used commercial contrast agents in human MR examinations

  10. The Method of Culture Contrast

    DEFF Research Database (Denmark)

    Hasse, Cathrine; Trentemøller, Stine; Motzkau, Johanna

    2009-01-01

    ) framework on which the research is conducted. First we present a recent study of European universities as culturally diverse working places and we present an approach in which the researcher's emic and etic categorisations can be challenged when contrasted with each other (Hasse & Trentemøller 2008). Second......, we argue for the need for a shared understanding among researchers in international projects. We present the method of culture contrast as one way of dealing with the inevitable problem of different perceptions of words and their meanings. This method does not rest on the approach employed...... in traditional cross-cultural studies where a generalized category, as a tertium comparationis, is identified and tested in two (or more) different cultural settings. Through a reflexive process of research, we show how patterns of connections can be contrasted and thus made explicit leading to new...

  11. Quantitative neutron phase contrast tomography

    International Nuclear Information System (INIS)

    Conventional neutron radiography and tomography are based on the attenuation contrast induced by the sample. In the last few years, another source of image contrast, the so-called phase contrast, has been introduced. The imaging methods to detect phase changes due to the interaction with the sample improve continuously, and several techniques are established. One method to discover phase shifts is diffraction enhanced imaging using a double-crystal diffractometer. It is described how the refractive index distribution of a sample can be recovered quantitatively in tomographic reconstructions from data achieved by this technique. Using reference samples with a well-known refractive index distribution, high accuracy with deviations of only a few per cent could be found in the reconstructions for all used materials

  12. Contrast-guided image interpolation.

    Science.gov (United States)

    Wei, Zhe; Ma, Kai-Kuang

    2013-11-01

    In this paper a contrast-guided image interpolation method is proposed that incorporates contrast information into the image interpolation process. Given the image under interpolation, four binary contrast-guided decision maps (CDMs) are generated and used to guide the interpolation filtering through two sequential stages: 1) the 45(°) and 135(°) CDMs for interpolating the diagonal pixels and 2) the 0(°) and 90(°) CDMs for interpolating the row and column pixels. After applying edge detection to the input image, the generation of a CDM lies in evaluating those nearby non-edge pixels of each detected edge for re-classifying them possibly as edge pixels. This decision is realized by solving two generalized diffusion equations over the computed directional variation (DV) fields using a derived numerical approach to diffuse or spread the contrast boundaries or edges, respectively. The amount of diffusion or spreading is proportional to the amount of local contrast measured at each detected edge. The diffused DV fields are then thresholded for yielding the binary CDMs, respectively. Therefore, the decision bands with variable widths will be created on each CDM. The two CDMs generated in each stage will be exploited as the guidance maps to conduct the interpolation process: for each declared edge pixel on the CDM, a 1-D directional filtering will be applied to estimate its associated to-be-interpolated pixel along the direction as indicated by the respective CDM; otherwise, a 2-D directionless or isotropic filtering will be used instead to estimate the associated missing pixels for each declared non-edge pixel. Extensive simulation results have clearly shown that the proposed contrast-guided image interpolation is superior to other state-of-the-art edge-guided image interpolation methods. In addition, the computational complexity is relatively low when compared with existing methods; hence, it is fairly attractive for real-time image applications. PMID:23846469

  13. Quantitative analysis of image contrast in phase contrast STEM for low dose imaging

    International Nuclear Information System (INIS)

    This work quantitatively evaluates the contrast in phase contrast images of thin vermiculite crystals recorded by TEM and aberration-corrected bright-field STEM. Specimen movement induced by electron irradiation remains a major problem limiting the phase contrast in TEM images of radiation-sensitive specimens. While spot scanning improves the contrast, it does not eliminate the problem. One possibility is to utilise aberration-corrected scanning transmission electron microscopy (STEM) with an Angstrom-sized probe to illuminate the sample, and thus further reduce irradiation-induced specimen movement. Vermiculite is relatively radiation insensitive in TEM to electron fluences below 100,000 e-/A2 and this is likely to be similar for STEM although different damage mechanisms could occur. We compare the performance of a TEM with a thermally assisted field emission electron gun (FEG) and charge coupled device (CCD) image capture to the performance of STEMs with spherical aberration correction, cold field emission electron sources and photomultiplier tube image capture at a range of electron fluences and similar illumination areas. We show that the absolute contrast of the phase contrast images obtained by aberration-corrected STEM is better than that obtained by TEM. Although the STEM contrast is higher, the efficiency of collection of electrons in bright field STEM is still much less than that in bright field TEM (where for thin samples virtually all the electrons contribute to the image), and the SNR of equivalent STEM images is three times lower. This is better than expected, probably due to the absence of a frequency dependent modulation transfer function in the STEM detection system. With optimisation of the STEM bright field collection angles, the efficiency may approach that of bright field TEM, and if reductions in beam-induced specimen movement are found, STEM could surpass the overall performance of TEM.

  14. Contrast enhancement in computed tomography

    International Nuclear Information System (INIS)

    There appears little question that cerebral contrast enhancement by iodinated material is to a great extent a reflection of a loss of integrity of the blood-brain barrier, expect in those instances where large vascular channels contain a sufficiently large pool of iodinated material of sufficient density and size to be visualized directly. (orig./VJ)

  15. Abnormal enhancement after contrast injection

    International Nuclear Information System (INIS)

    Two factors are involved in the enhancement of pathological processes at CT: the vascular pool and extra-vascular diffusion ot the contrast agent. Enhancement is of considerable use in visualising and delineating these pathologies but is of only limited interest as regards their characterisation. (orig./VJ)

  16. Signal Fluctuation Sensitivity: an improved metric for optimizing detection of resting-state fMRI networks

    OpenAIRE

    DeDora, Daniel J.; Nedic, Sanja; Katti, Pratha; Arnab, Shafique; Wald, Lawrence L.; Takahashi, Atsushi; Dijk, Koene R.A.Van; Strey, Helmut H.; Mujica-Parodi, Lilianne R.

    2015-01-01

    Task-free connectivity analyses have emerged as a powerful tool in functional neuroimaging. Because the cross-correlations that underlie connectivity measures are sensitive to distortion of time-series, here we used a novel dynamic phantom to provide a ground truth for dynamic fidelity between blood oxygen level dependent (BOLD)-like inputs and fMRI outputs. We found that the de facto quality-metric for task-free fMRI, temporal signal to noise ratio (tSNR), correlated inversely with dynamic f...

  17. Cortical and brain stem changes in neural activity during static handgrip and postexercise ischemia in humans

    DEFF Research Database (Denmark)

    Sander, Mikael; Macefield, Vaughan G; Henderson, Luke A

    2010-01-01

    , and to differentiate between central command and reflex inputs, we used blood oxygen level-dependent (BOLD) functional MRI (fMRI) of the whole brain (3 T). Subjects performed submaximal static handgrip exercise for 2 min followed by 6 min of PEI; MSNA was recorded on a separate day. During the contraction phase......Static isometric exercise increases muscle sympathetic nerve activity (MSNA) and mean arterial pressure, both of which can be maintained at the conclusion of the exercise by occlusion of the arterial supply [postexercise ischemia (PEI)]. To identify the cortical and subcortical sites involved...

  18. Total neuroenergetics support localized brain activity: Implications for the interpretation of fMRI

    OpenAIRE

    Hyder, Fahmeed; Rothman, Douglas L.; Shulman, Robert G.

    2002-01-01

    In α-chloralose-anesthetized rats, changes in the blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal (ΔS/S), and the relative spiking frequency of a neuronal ensemble (Δν/ν) were measured in the somatosensory cortex during forepaw stimulation from two different baselines. Changes in cerebral oxygen consumption (ΔCMRO2/CMRO2) were derived from the BOLD signal (at 7T) by independent determinations in cerebral blood flow (ΔCBF/CBF) and volume (ΔCBV/CBV). The spiking frequency ...

  19. Hemodynamic and tubular changes induced by contrast media.

    Science.gov (United States)

    Caiazza, Antonella; Russo, Luigi; Sabbatini, Massimo; Russo, Domenico

    2014-01-01

    The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI. PMID:24678510

  20. Low Contrast Dielectric Metasurface Optics

    CERN Document Server

    Zhan, Alan; Trivedi, Rahul; Dodson, Chris; Majumdar, Arka

    2015-01-01

    The miniaturization of current image sensors is largely limited by the volume of the optical elements. Using a sub-wavelength patterned quasi-periodic structure, also known as a metasurface, one can build planar optical elements based on the principle of diffraction. However, it was believed that high refractive index materials are required for metasurface optics. Here, we show that one can employ the design principles of a metasurface even with low contrast materials, such as silicon nitride. We validate our theory by fabricating and experimentally characterizing several silicon nitride based lenses and vortex beam generators . The fabricated lenses achieved beam spots of less than 1 {\\mu}m with numerical apertures as high as ~ 0.75. A transmission efficiency of 90% and focusing efficiency of 40% in the visible regime was observed. Our results pave the way towards building low-loss metasurface based optical elements at visible frequencies using low contrast materials.

  1. High-contrast imaging testbed

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K; Silva, D; Poyneer, L; Macintosh, B; Bauman, B; Palmer, D; Remington, T; Delgadillo-Lariz, M

    2008-01-23

    Several high-contrast imaging systems are currently under construction to enable the detection of extra-solar planets. In order for these systems to achieve their objectives, however, there is considerable developmental work and testing which must take place. Given the need to perform these tests, a spatially-filtered Shack-Hartmann adaptive optics system has been assembled to evaluate new algorithms and hardware configurations which will be implemented in these future high-contrast imaging systems. In this article, construction and phase measurements of a membrane 'woofer' mirror are presented. In addition, results from closed-loop operation of the assembled testbed with static phase plates are presented. The testbed is currently being upgraded to enable operation at speeds approaching 500 hz and to enable studies of the interactions between the woofer and tweeter deformable mirrors.

  2. Low Contrast Dielectric Metasurface Optics

    OpenAIRE

    Zhan, Alan; Colburn, Shane; Trivedi, Rahul; Dodson, Chris; Majumdar, Arka

    2015-01-01

    The miniaturization of current image sensors is largely limited by the volume of the optical elements. Using a sub-wavelength patterned quasi-periodic structure, also known as a metasurface, one can build planar optical elements based on the principle of diffraction. However, it was believed that high refractive index materials are required for metasurface optics. Here, we show that one can employ the design principles of a metasurface even with low contrast materials, such as silicon nitride...

  3. An fMRI study of behavioral response inhibition in adolescents with and without histories of heavy prenatal alcohol exposure

    Science.gov (United States)

    Ware, Ashley L.; Infante, M. Alejandra; O’Brien, Jessica W.; Tapert, Susan F.; Jones, Kenneth Lyons; Riley, Edward P.; Mattson, Sarah N.

    2014-01-01

    Heavy prenatal alcohol exposure results in a range of deficits, including both volumetric and functional changes in brain regions involved in response inhibition such as the prefrontal cortex and striatum. The current study examined blood oxygen level-dependent (BOLD) response during a stop signal task in adolescents (ages 13–16 y) with histories of heavy prenatal alcohol exposure (AE, n = 21) and controls (CON, n = 21). Task performance was measured using percent correct inhibits during three difficulty conditions: easy, medium, and hard. Group differences in BOLD response relative to baseline motor responding were examined across all inhibition trials and for each difficulty condition separately. The contrast between hard and easy trials was analyzed to determine whether increasing task difficulty affected BOLD response. Groups had similar task performance and demographic characteristics, except for full scale IQ scores (AE < CON). The AE group demonstrated greater BOLD response in frontal, sensorimotor, striatal, and cingulate regions relative to controls, especially as task difficulty increased. When contrasting hard vs. easy inhibition trials, the AE group showed greater medial/superior frontal and cuneus BOLD response than controls. Results were unchanged after demographics and FAS diagnosis were statistically controlled. This was the first fMRI study to utilize a stop signal task, isolating fronto-striatal functioning, to assess response inhibition and the effects task difficulty in adolescents with prenatal alcohol exposure. Results suggest that heavy prenatal alcohol exposure disrupts neural function of this circuitry, resulting in immature cognitive processing and motor-association learning and neural compensation during response inhibition. PMID:25281280

  4. Functional magnetic resonance imaging of basal ganglia. Activation mapping with FLASH sequences for BOLD contrast and high resolution; Funktionelle Magnetresonanztomographie der Basalganglien. Einsatz von FLASH-Sequenzen zum Aktivitaetsmapping mit BOLD-Kontrast und Hochaufloesung

    Energy Technology Data Exchange (ETDEWEB)

    Seelos, K.C. [Inst. fuer Radiologische Diagnostik, Klinikum Grosshadern, Univ. Muenchen (Germany); Bucher, S.F. [Neurologische Klinik und Poliklinik, Klinikum Grosshadern, Univ. Muenchen (Germany); Stehling, M.K. [Inst. fuer Radiologische Diagnostik, Klinikum Grosshadern, Univ. Muenchen (Germany); Oertel, W.H. [Neurologische Klinik und Poliklinik, Klinikum Grosshadern, Univ. Muenchen (Germany); Reiser, M. [Inst. fuer Radiologische Diagnostik, Klinikum Grosshadern, Univ. Muenchen (Germany)

    1995-04-01

    The activation pattern of putamen, internal and external division of globus pallidus was investigated during rapid pronation and supination of the right and left hand in 12 normal volunteers using a FLASH sequence with high resolution for functional magnetic resonance imaging (fMRI) at 1.5 T. The chosen paradigm for motor function led to a signal increase within the basal ganglia between 3 and 23%, depending on the structure and individual subject. In all cases significant activation could be found contralateral to the moving hand. In six cases activation was also found on the ipsilateral side. The activated areas within putamen, internal and external division of globus pallidus were less than 5 mm{sup 2}. These first results indicate that fMRI studies of basal ganglia are feasible and might be suitable for analyzing basal ganglia disorders. (orig.) [Deutsch] Das Aktivierungsmuster von Putamen, Globus pallidus internus und externus waehrend schneller Pronation und Supination von rechter und linker Hand wurde bei 12 normalen Probanden mit Hilfe einer fuer die funktionelle Magnetresonanztomographie (fMRT) geeigneten hochaufloesenden FLASH-Sequenz bei 1,5 Tesla untersucht. Der durch das Bewegungsparadigma verursachte Signalanstieg innerhalb der Basalganglien lag je nach Struktur und untersuchtem Individuum zwischen 3 und 23%. In allen Faellen war kontralateral zur bewegten Hand ein signifikanter Aktivitaetsanstieg nachweisbar. In 6 Faellen war auch auf der ipsilateralen Seite eine Aktivitaet nachweisbar. Die aktivierten Areale innerhalb von Putamen, Globus pallidus internus und externus waren nicht groesser als 5 mm{sup 2}. Diese ersten Ergebnisse zeigen, dass magnetresonanztomographische Funktionsuntersuchungen im Bereich der Basalganglien moeglich sind und geeignet erscheinen, um Erkrankungen dieser Systeme zu analysieren. (orig.)

  5. Contrast media in MR mammography

    International Nuclear Information System (INIS)

    A standardized relationship between concentration of contrast media and normalized signal intensity should be the basis of a diagnostic evaluation of MR-mammography at different sites and with different sequences. In this work we compared the dynamic range of the MR-compatible contrast medium MagnevistR at different sequences and machines. For this purpose we made measurements with a phantom, consisting of MR-compatible glass tubes filled with contrast medium of different concentrations. The glass tubes were placed in a water bath. All measurements were made with breast coils. The signal intensity of the glass tubes was normalized to the signal intensity of the native probe (water=1). These normalized dynamic curves were compared with each other in order to find, for the different machines, the sequence which is nearest to be defined 'Standard-Curve'. As this task proved not possible for all machines, we measured how the dynamic curves of the different machines related to the 'Standard-Curve'. For all sequences we made also measurements with a female student to assure the quality of the pictures. Thus the participating radiologists can now compare their dynamic measurements of breast lesions with each other. (orig.)

  6. Electrofluidic systems for contrast management

    Science.gov (United States)

    Rebello, Keith J.; Maranchi, Jeffrey P.; Tiffany, Jason E.; Brown, Christopher Y.; Maisano, Adam J.; Hagedon, Matthew A.; Heikenfeld, Jason C.

    2012-06-01

    Operating in dynamic lighting conditions and in greatly varying backgrounds is challenging. Current paints and state-ofthe- art passive adaptive coatings (e.g. photochromics) are not suitable for multi- environment situations. A semi-active, low power, skin is needed that can adapt its reflective properties based on the background environment to minimize contrast through the development and incorporation of suitable pigment materials. Electrofluidic skins are a reflective display technology for electronic ink and paper applications. The technology is similar to that in E Ink but makes use of MEMS based microfluidic structures, instead of simple black and white ink microcapsules dispersed in clear oil. Electrofluidic skin's low power operation and fast switching speeds (~20 ms) are an improvement over current state-ofthe- art contrast management technologies. We report on a microfluidic display which utilizes diffuse pigment dispersion inks to change the contrast of the underlying substrate from 5.8% to 100%. Voltage is applied and an electromechanical pressure is used to pull a pigment dispersion based ink from a hydrophobic coated reservoir into a hydrophobic coated surface channel. When no voltage is applied, the Young-Laplace pressure pushes the pigment dispersion ink back down into the reservoir. This allows the pixel to switch from the on and off state by balancing the two pressures. Taking a systems engineering approach from the beginning of development has enabled the technology to be integrated into larger systems.

  7. Contrast study on cognitive function with MRI and positron emission tomography imaging in transient global amnesia%短暂性全面遗忘症的认知功能和MRI及PET的对比研究

    Institute of Scientific and Technical Information of China (English)

    贾建军; 王鲁宁; 尹岭; 汤洪川

    2002-01-01

    Objective To study cognitive function and cerebral metabolic changes in patients with transient global amnesia (TGA). Methods Three patients with TGA were given mini-mental state examination (MMSE), revised Wechsler memory scale (WMS-R) examination and magnetic resonance imaging (MRI) scans after they had been diagnosed as TGA. Using 18 F labelled deoxyglucose as tracer, patients were given a positron emission tomography (PET) examination at different periods during recovery. Results No obvious abnormality was found in MMSE and MRI scans in the three patients. However, WMS-R examination and cerebral PET imaging displayed cognitive dysfunction of varying degrees and low metabolism in local areas related to memory in 2 of 3 patients. Conclusions In TGA patients, cognitive function and cerebral metabolic levels are closely correlated with duration of symptoms. It is necessary to stop the TGA attack as quickly as possible early time.%目的研究短暂性全面遗忘症(transient global amnesia,TGA)患者认知功能及脑代谢状况.方法对3例临床诊断为TGA的患者分别行简易心理测试(MMSE)、修订的韦氏记忆量表(WMS-R)测定和脑核磁共振成像(MRI)检查,在恢复后不同时间以18氟标记的脱氧葡萄糖(18 F-FDG)为示踪剂行脑正电子发射型计算机断层扫描(positron emission tomography,PET)成像,并对其图像、量表测试结果与病史作对照研究.结果 3例患者MMSE测试及MRI扫描均未见明显异常,而WMS-R测试及PET成像显示:1例正常,另外2例有不同程度认知功能损害,与记忆相关结构有不同程度的低代谢.结论 TGA患者认知功能及局部脑代谢与其症状持续时间密切相关,尽早终止其发作是必要的.

  8. Radionuclide left ventricular dV/dt for the assessment of cardiac function in patients with coronary disease. [/sup 99m/Ic-labelled red blood cells and contrast radiography

    Energy Technology Data Exchange (ETDEWEB)

    Bianco, J.A.; Makey, D.G.; Laskey, W.K.; Shafer, R.B.

    1979-01-01

    To investigate potential uses of left-ventricular (LV) systolic ejection rate (LV dV/dt) in the evaluation of LV function, we examined the effect of exercise, angiotensin, and leg raising on LV ejection fraction and LV dV/dt in patients with coronary-artery disease. The following observations were made: (a) LV ejection fraction and dV/dt changed proportionately, but in opposite directions, during supine exercise; (b) LV ejection fraction and dV/dt decreased to a similar extent during angiotensin infusions; and (c) LV ejection fraction and dV/dt were unchanged by leg raising. The changes in peak and mean LV dV/dt were similar. Regardless of the physiologic state, peak LV dV/dt occurred during the first third of systole. These data imply that in this population there were no specific advantages of LV dV/dt over LV ejection fraction in the evaluation of LV performance.

  9. 运动想象疗法对急性脑梗死患者上肢瘫痪的效果及脑功能MRI的改变%Effects and changes of brain functional MRI of motor imagery therapy on acute cerebral infarction patients with upper limb paralysis

    Institute of Scientific and Technical Information of China (English)

    冉茂胜; 叶建军; 马东兵; 张莉; 胡杰杰; 杨旭君; 乔小民; 姜晓萍

    2013-01-01

    Objective To investigate the effects and changes of brain functional MRI (fMRI) of motor imagery therapy on acute cerebral infarction ( ACI) patients with upper limb paralysis. Methods Seventy cases of ACI patients with hemiplegia were randomly divided into the control group (drug therapy + exercise) and motor imagery therapy group, each group had 35 cases. The treatment of motor imagery therapy group was on the basis of control group, add into motor imagery therapy, 2 times a day, for 30 d. Before and 30 d after treatment, the patients were scored by Fugl-Meyer scale (FMA) and functional independence measure scale (FIM) , the active range of motion ( AROM) of ipsilateral wrist was measured by a protractor, and the brain movement activation range was measured by blood oxygen level dependent fMRI. Results After treatment, the FMA, FIM scores of paralysis upper extremity, the AROM and range of brain activation were significantly higher or bigger than before treatment in the two groups (P<0. 05 -0.01). And these indicators of motor imagery therapy group were significantly higher or bigger than those in the control group (P<0. 05 —0.01). Conclusions Motor imagery therapy can promote the recovery of the upper limb motor function in acute cerebral infarction patients with hemiplegia, and expand the brain movement activation range on fMRI.%目的 研究运动想象疗法对急性脑梗死患者上肢瘫痪的效果及脑功能MRI(fMRI)的改变.方法 70例脑梗死偏瘫患者,随机分为对照组(药物治疗+运动)和运动想象治疗组,每组35例.运动想象治疗组在对照组的治疗基础上,进行运动想象疗法,每天2次,连续30 d.在治疗前和治疗后30 d,给患者进行Fugl-Meyer量表(FMA)、功能独立性评定量表(FIM)评分,用量角器测定患侧手腕主动活动范围(AROM);用血氧水平依赖性fMRI测定脑运动激活区范围.结果 两组患者治疗后瘫痪上肢的FMA、FIM评分、AROM及脑激活区的范围均明

  10. Generalised use of contrast degradation and contrast improvement factors in diagnostic radiology. Application to vanishing contrast

    International Nuclear Information System (INIS)

    Although field area and object thickness are important parameters in comparisons of techniques for optimal reduction of scattered radiation to the image, they are in practice seldom varied. The authors suggest that contrast degradation (CDF) and contrast improvement (CIF) factors be more frequently used and appropriately defined to make the dependence of CDF and CIF on field area (collimation) and object thickness (compression) explicit. Definitions are formulated and the results of experiments and Monte Carlo calculations (comprising effects of collimation, compression, air gap, antiscatter grid, detector thickness) cited to illustrate their usefulness. Currently used expressions for CIF (derived assuming monoenergetic radiation) lack a vector to account for the change in primary contrast caused by the antiscatter method when this affects the energy distribution of the transmitted primary photons (grids and compression) or the fractions of photon energy imparted to the detector (when comparing different detectors). Values of this factor are calculated for some cases. The appropriate choice of physical quantity to be used in the formulae for CDF and CIF is discussed. The energy imparted to the detector is advocated since this is directly related to the detector signals forming the image on, e.g. the x-ray film. (author)

  11. Binocular summation of contrast remains intact in strabismic amblyopia

    OpenAIRE

    Baker, Daniel H.; Meese, Tim S.; Mansouri, Behzad; Hess, Robert F.

    2007-01-01

    PURPOSE. Strabismic amblyopia is typically associated with several visual deficits, including loss of contrast sensitivity in the amblyopic eye and abnormal binocular vision. Binocular summation ratios (BSRs) are usually assessed by comparing contrast sensitivity for binocular stimuli (sensBIN) with that measured in the good eye alone (sensGOOD), giving BSR = sensBIN/sensGOOD. This calculation provides an operational index of clinical binocular function, but does not assess whether neuronal m...

  12. Contrast sensitivity and visual disability in chronic simple glaucoma

    OpenAIRE

    Ross, J E; Bron, A J; Clarke, D D

    1985-01-01

    A battery of vision tests was used to quantify visual defect in a group of 50 patients with chronic simple glaucoma. The vision tests were near and distance visual acuity, visual fields, and contrast sensitivity to static and temporally modulated sinusoidal grating patterns. Of these, static contrast sensitivity function appears to be the most sensitive method of measuring visual defect in glaucoma patients. The visual disability experienced by the glaucoma patients was quantified by means of...

  13. Contrast-induced acute kidney injury: how much contrast is safe?

    LENUS (Irish Health Repository)

    Keaney, John J

    2013-02-14

    Iodinated contrast media (CM) are used in many investigations that a patient may undergo during the course of an in-patient stay. For the vast majority of patients, exposure to CM has no sequelae; however, in a small percentage, it can result in a worsening in renal function termed contrast-induced acute kidney injury (CI-AKI). CI-AKI is one of the leading causes of in-hospital renal dysfunction. It is associated with a significant increase in morbidity and mortality as well as an increased length of hospital stay and costs. Unfortunately, the results of extensive research into pharmacological inventions to prevent CI-AKI remain disappointing. In this article, we briefly outline the pathophysio