Home About us Contact
|
Home About us Contact | ||
|
|
||
Positron Emission Tomography (positron + emission_tomography)
Kinds of Positron Emission Tomography Terms modified by Positron Emission Tomography Selected AbstractsDopamine release in ventral striatum of pathological gamblers losing moneyACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2010J. Linnet Linnet J, Peterson E, Doudet DJ, Gjedde A, Møller A. Dopamine release in ventral striatum of pathological gamblers losing money. Objective:, To investigate dopaminergic neurotransmission in relation to monetary reward and punishment in pathological gambling. Pathological gamblers (PG) often continue gambling despite losses, known as ,chasing one's losses'. We therefore hypothesized that losing money would be associated with increased dopamine release in the ventral striatum of PG compared with healthy controls (HC). Method:, We used Positron Emission Tomography (PET) with [11C]raclopride to measure dopamine release in the ventral striatum of 16 PG and 15 HC playing the Iowa Gambling Task (IGT). Results:, PG who lost money had significantly increased dopamine release in the left ventral striatum compared with HC. PG and HC who won money did not differ in dopamine release. Conclusion:, Our findings suggest a dopaminergic basis of monetary losses in pathological gambling, which might explain loss-chasing behavior. The findings may have implications for the understanding of dopamine dysfunctions and impaired decision-making in pathological gambling and substance-related addictions. [source] The functional neuroanatomy of geriatric depressionINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 8 2009Gwenn S. Smith Abstract Objective Positron Emission Tomography (PET) studies of cerebral glucose metabolism have demonstrated sensitivity in evaluating the functional neuroanatomy of treatment response variability in depression, as well as in the early detection of functional changes associated with incipient cognitive decline. The evaluation of cerebral glucose metabolism in late life depression may have implications for understanding treatment response variability, as well as evaluating the neurobiological basis of depression in late life as a risk factor for dementia. Methods Sixteen patients with geriatric depression and 13 comparison subjects underwent resting PET studies of cerebral glucose metabolism, as well as magnetic resonance (MR) imaging scans to evaluate brain structure. Results Cerebral glucose metabolism was elevated in geriatric depressed patients relative to comparison subjects in anterior (right and left superior frontal gyrus) and posterior (precuneus, inferior parietal lobule) cortical regions. Cerebral atrophy (increased cerebrospinal fluid [CSF] and decreased grey and white matter volumes) were observed in some of these regions, as well. Regional cerebral metabolism was positively correlated with severity of depression and anxiety symptoms. Conclusions In contrast to decreased metabolism observed in normal aging and neurodegenerative conditions such as Alzheimer's disease, cortical glucose metabolism was increased in geriatric depressed patients relative to demographically matched controls, particularly in brain regions in which cerebral atrophy was observed, which may represent a compensatory response. Copyright © 2009 John Wiley & Sons, Ltd. [source] Clinical Application of PET/CT Fusion Imaging for Three-Dimensional Myocardial Scar and Left Ventricular Anatomy during Ventricular Tachycardia AblationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2009JING TIAN M.D., Ph.D. Background: Image integration has the potential to display three-dimensional (3D) scar anatomy and facilitate substrate characterization for ventricular tachycardia (VT) ablation. However, the current generation of clinical mapping systems cannot display 3D left ventricle (LV) anatomy with embedded 3D scar reconstructions or allow display of border zone and high-resolution anatomic scar features. Objective: This study reports the first clinical experience with a mapping system allowing an integrated display of 3D LV anatomy with detailed 2D/3D scar and border zone reconstruction. Methods: Ten patients scheduled for VT ablation underwent contrast-enhanced computed tomography (CT) and Rubidium-82 perfusion/F-18 Fluorodeoxyglucose metabolic Positron Emission Tomography (PET) imaging to reconstruct 3D LV and scar anatomy. LV and scar models were co-registered using a 3D mapping system and analyzed with a 17-segment model. Metabolic thresholding was used to reconstruct the 3D border zone. Real-time display of CT images was performed during ablation. Results: Co-registration (error 4.3 ± 0.7 mm) allowed simultaneous visualization of 3D LV anatomy and embedded scar and guided additional voltage mapping. Segments containing homogenous or partial scar correlated in 94.4% and 85.7% between voltage maps and 3D PET scar reconstructions, respectively. Voltage-defined scar and normal myocardium had relative FDG uptakes of 40 ± 13% and 89 ± 30% (P < 0.05). The 3D border zone correlated best with a 46% metabolic threshold. Real-time display of registered high-resolution CT images allowed the simultaneous characterization of scar-related anatomic changes. Conclusion: Integration of PET/CT reconstruction allows simultaneous 3D display of myocardial scar and border zone embedded into the LV anatomy as well as the display of detailed scar anatomy. Multimodality imaging may enable a new image-guided approach to substrate-guided VT ablation. [source] The Role of Positron Emission Tomography in Evaluation of Alterations in Cardiac Efficiency after Cardiac Resynchronization TherapyJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2008CLAUDIA YPENBURG M.D. No abstract is available for this article. [source] Synthesis of 13C-labelled cinnamonitrileJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2002Elizabeth M. Zippi Abstract 13C-labelled cinnamonitrile, a compound that possesses both the aromatic functionality of styrene and the nitrile functionality of acrylonitrile has been synthesized in one step using , -bromostyrene and potassium [13C]cyanide. The preparation of a target material using 13C -labelled cinnamonitrile may provide a cost-effective method for producing nitrogen-13 via proton irradiation for Positron Emission Tomography. Copyright © 2002 John Wiley & Sons, Ltd. [source] Tissue Distribution, Autoradiography, and Metabolism of 4-(2,-Methoxyphenyl)-1-[2, -[N -2,-Pyridinyl)- p -[18F]Fluorobenzamido]ethyl]piperazine (p -[18F]MPPF), a New Serotonin 5-HT1A Antagonist for Positron Emission TomographyJOURNAL OF NEUROCHEMISTRY, Issue 2 2000An In Vivo Study in Rats The in vivo behavior of 4-(2,-methoxyphenyl)-1-[2,-[N -(2,-pyridinyl)- p -[18F]fluorobenzamido]ethyl]-piperazine (p -[18F]MPPF), a new serotonin 5-HT1A antagonist, was studied in awake, freely moving rats. Biodistribution studies showed that the carbon-fluorine bond was stable in vivo, that this compound was able to cross the blood-brain barrier, and that a general diffusion equilibrium could account for the availability of the tracer. The great quantity of highly polar metabolites found in plasma did not contribute to the small amounts of metabolites found in hippocampus, frontal cortex, and cerebellum. Exvivo p -[18F]MPPF and in vitro 8-hydroxy-2-(di- n -[3H]propylamino)tetralin autoradiography were compared both qualitatively and quantitatively. Qualitative evaluation proved that the same brain regions were labeled and that the p -[18F]MPPF labeling is (a) in total agreement with the known distribution of 5-HT1A receptors in rats and (b) characterized by very low nonspecific binding. Quantitative comparison demonstrated that the in vivo labeling pattern obtained with p -[18F]MPPF cannot be explained by differences in regional blood flow, capillary density, or permeability. The 5-HT1A specificity of p -[18F]MPPF and binding reversibility were confirmed in vivo with displacement experiments. Thus, this compound can be used to evaluate parameters characterizing 5-HT1A binding sites in the brain. [source] Combined Use of F-18 Fluorocholine Positron Emission Tomography and Magnetic Resonance Spectroscopy for Brain Tumor EvaluationJOURNAL OF NEUROIMAGING, Issue 3 2004Sandi A. Kwee MD ABSTRACT Background. Choline metabolism is often abnormal in malignant brain tumors.Methods. Brain positron emission tomography (PET) imaging with F-18 fluorocholine (FCH) was performed on 2 patients with intracranial lesions suspected to be high-grade malignant gliomas on the basis of magnetic resonance (MR) imaging and multivoxel 1H-MR spectroscopic imaging (MRSI) findings. Standardized uptake value (SUV) measurements on PET were compared with measurements of choline/creatine metabolite ratio on MRSI in corresponding regions. Brain biopsy revealed glioblastoma multiforme (GBM) in one case and demyelinating disease in the other.Results. In the case of GBM, the tumor demonstrated increased FCH uptake on PET. The mean and maximum SUV in areas of the tumor correlated with regional choline/ creatine ratio measurements (r= 0.76,P < .001;r= 0.83,P < .001, respectively). In the case of tumefactive demyelinating lesions, the lesion demonstrated low FCH uptake, which did not correlate with choline/ creatine ratio measurements.Conclusions. Assessments of choline metabolism may aid in evaluating intracranial mass lesions. [source] Alterations in Brain Serotonin Synthesis in Male Alcoholics Measured Using Positron Emission TomographyALCOHOLISM, Issue 2 2009Masami Nishikawa Background:, A consistent association between low endogenous 5HT function and high alcohol preference has been observed, and a number of serotonergic manipulations (uptake blockers, agonists) alter alcohol consumption in animals and humans. Studies have also shown an inverse relationship between alcohol use and cerebrospinal fluid levels of serotonin metabolites, suggesting that chronic alcohol consumption produces alterations in serotonin synthesis or release. Methods:, The objective of the study was to characterize regional brain serotonin synthesis in nondepressed chronic alcoholics at treatment entry in comparison to normal nonalcoholic controls using PET and the tracer ,-[11C]-methyl- l -tryptophan. Results:, Comparisons of the alcoholics and controls by SPM found that there were significant differences in the rate of serotonin synthesis between groups. Serotonin synthesis was significantly lower among alcoholics in Brodmann Area (BA) 9, 10, and 32. However, serotonin synthesis among the alcoholics group was significantly higher than controls at BA19 in the occipital lobe and around the transverse temporal convolution in the left superior temporal gyrus (BA41). In addition, there were correlations between regional serotonin synthesis and a quantity-frequency measure of alcohol consumption. Regions showing a significant negative correlation with QF included the bilateral rectus gyri (BA11) in the orbitofrontal area, the bilateral medial frontal area (BA6), and the right amygdala. Conclusions:, Current alcoholism is associated with serotonergic abnormalities in brain regions that are known to be involved in planning, judgment, self-control, and emotional regulation. [source] Re: Axillary Staging Using Positron Emission Tomography in Breast Cancer Patients Qualifying for Sentinel Lymph Node BiopsyTHE BREAST JOURNAL, Issue 2 2004Kirby I. Bland MDArticle first published online: 10 MAR 200 No abstract is available for this article. [source] Positron Emission Tomography Applied to Fluidization EngineeringTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2005Chutima Dechsiri Abstract The movement of particles in a laboratory fluidized bed has been studied using Positron Emission Tomography (PET). With this non-invasive technique both pulses of various shapes and single tracer particles were followed in 3-D. The equipment and materials used made it possible to label actual bed particles as tracer. This paper briefly describes the data analysis, some of the results and compares them with a stochastic model. The results confirm the basic assumptions of the model qualitatively but not quantitatively. Further analysis of the results indicates that the system exhibits gulf-streaming, a feature which is not yet accounted for in the model, but is common in fluidized beds in practice. On a étudié le mouvement des particules dans un lit fluidisé de laboratoire par la tomographie à émission de positrons (PET). Cette technique non intrusive a permis de suivre en 3-D des impulsions de formes diverses aussi bien que des particules traçantes uniques en 3-D. L'équipement et les matériaux utilisés ont permis d'employer des particules de lit réelles comme traceurs. On décrit brièvement dans cet article l'analyse des données et certains des résultats, puis une comparaison est effectuée avec un modèle stochastique. Les résultats confirment les hypothèses de base du modèle de façon qualitative mais non quantitative. Une analyse plus approfondie des résultats indique que le système montre un phénomène de « gulf-streaming », une caractéristique pas encore prise en compte dans le modèle mais qui est courante dans les lits fluidisés réels. [source] Current use of 18F-Fluorodeoxyglucose Positron Emission Tomography and Combined Positron Emission Tomography and Computed Tomography in Squamous Cell Carcinoma of the Head and NeckTHE LARYNGOSCOPE, Issue 11 2005Lee A. Zimmer The history and physical examination, computed tomography (CT) and magnetic resonance imaging are the cornerstones for identifying new and recurrent cancers of the head and neck. The advent of positron emission tomography (PET) and combined PET/CT imaging technology is a promising development. These modalities have the potential to help stage patients presenting with head and neck cancer, identify responses to nonsurgical therapy, and allow earlier detection of recurrence in the hope of improving survival. The following paper provides a brief history of PET and PET/CT imaging. The current PET and PET/CT literature for squamous cell carcinoma of the head and neck is reviewed, and specific recommendations for its use are provided. [source] Positron Emission Tomography in Clinical Islet TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2009O. Eriksson The fate of islets in clinical transplantation is unclear. To elude on this positron emission tomography combined with computed tomography (PET/CT) was performed for 60 min during islet transplantation in five patients receiving six transplants. A fraction of the islets (23%) were labeled with 18F-fluorodeoxyglucose ([18F]FDG) and carefully mixed with unlabeled islets just prior to intraportal transplantation. The peak radioactivity concentration in the liver was found at 19 min after start of islet infusion and corresponded to only 75% of what was expected, indicating that islets are lost during the transplantation procedure. No accumulation of radioactivity was found in the lungs. A nonphysiological peak of C-peptide was found in plasma during and immediately after transplantation in all subjects. Distribution in the liver was heterogeneous with wide variations in location and concentration. Islets found in areas with concentrations of >400 IEQ/cc liver tissue varied between 1% and 32% of the graft in different subjects. No side effects attributed to the PET/CT procedure were found. Clinical outcome in all patients was comparable to that previously observed indicating that the [18F]FDG labeling procedure did not harm the islets. The technique has potential to be used to assess approaches to enhance islet survival and engraftment in clinical transplantation. [source] In Vivo Distribution of Liposome-Encapsulated Hemoglobin Determined by Positron Emission TomographyARTIFICIAL ORGANS, Issue 2 2009Takeo Urakami Abstract Positron emission tomography (PET) is a noninvasive imaging technology that enables the determination of biodistribution of positron emitter-labeled compounds. Lipidic nanoparticles are useful for drug delivery system (DDS), including the artificial oxygen carriers. However, there has been no appropriate method to label preformulated DDS drugs by positron emitters. We have developed a rapid and efficient labeling method for lipid nanoparticles and applied it to determine the movement of liposome-encapsulated hemoglobin (LEH). Distribution of LEH in the rat brain under ischemia was examined by a small animal PET with an enhanced resolution. While the blood flow was almost absent in the ischemic region observed by [15O]H2O imaging, distribution of 18F-labeled LEH in the region was gradually increased during 60-min dynamic PET scanning. The results suggest that LEH deliver oxygen even into the ischemic brain from the periphery toward the core of ischemia. The real-time observation of flow pattern, deposition, and excretion of LEH in the ischemic rodent brain was possible by the new methods of positron emitter labeling and PET system with a high resolution. [source] 34 In vivo tumour hypoxia and carbonic anhydrase IX expression in xenografted human renal cell carcinoma animal models using probes, 124I-G250 pet, biodistribution and immunohistochemistry immunobiodistribution, and oxygen studiesBJU INTERNATIONAL, Issue 2006N. LAWRENTSCHUK Introduction:, Hypoxia stimulates angiogenesis and has been demonstrated in tumours where it correlates with resistance to treatment and poor prognosis. We have previously demonstrated hypoxia in human Renal Cell Carcinoma (RCC). The purpose of animal models was to further evaluate oxygen levels within RCC whilst also focusing on expression of the protein carbonic anhydrase IX (CA IX). This protein is stimulated by hypoxia and involved in angiogenesis and may be a potential tumour target for imaging and future therapies. Methods:, Balb/c nude mice had human RCC (SK-RC-52) xenografted subcutaneously. Tumours were grown to different volumes with oxygen levels measured. Further groups then had the radiolabelled monoclonal antibody 124I-G250 (that binds to CA IX) injected intravenously and had Positron Emission Tomography (PET), gamma counting and oxygen studies performed on days 0,1,2,3,5,7,10 and 14 post injection. Immunohistochemistry and autoradiography was also performed. Results:, An inverse relationship between tumour volume and hypoxia within the model was established (P < 0.001). Furthermore, CA IX was expressed by tumours with maximal uptake of 124I-G250 on days 2/3 by distribution with gamma counting that could be correlated with uptake on PET imaging. Conclusions:, The xenograft model confirms human RCC are hypoxic. Also, that the level of hypoxia is inversely proportional to tumour sise. A correlation was made between PET scanning with 124I-G250 and biodistribution within tumours by gamma counting confirming CAIX as an imaging and potential therapeutic target in RCC. [source] ChemInform Abstract: A Lipophilic Thioflavin-T Derivative for Positron Emission Tomography (PET) Imaging of Amyloid in Brain.CHEMINFORM, Issue 24 2002Chester A. Mathis Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Sentinel Lymph Node Excision and PET-CT in the Initial Stage of Malignant Melanoma: A Retrospective Analysis of 61 Patients with Malignant Melanoma in American Joint Committee on Cancer Stages I and IIDERMATOLOGIC SURGERY, Issue 4 2010JOACHIM KLODE MD BACKGROUND AND OBJECTIVES Sentinel lymph node excision (SLNE) for the detection of regional nodal metastases and staging of malignant melanoma has resulted in some controversies in international discussions. Positron emission tomography with computerized tomography (PET-CT), a noninvasive imaging procedure for the detection of regional nodal metastases, has increasingly become of interest. Our study is a direct comparison of SLNE and PET-CT in patients with early-stage malignant melanoma. MATERIALS AND METHODS We retrospectively analyzed data from 61 patients with primary malignant melanoma with a Breslow index greater than 1.0 mm. RESULTS Metastatic SLNs were found in 14 patients (23%); 17 metastatic lymph nodes were detected overall, only one of which was identified preoperatively using PET-CT. Thus, PET-CT showed a sensitivity of 5.9% and a negative predictive value of 78%. CONCLUSION SLNE is much more sensitive than PET-CT in discovering small lymph node metastases. We consider PET-CT unsuitable for the evaluation of early regional lymphatic tumor dissemination in this patient population and recommend that it be limited to malignant melanomas of American Joint Committee on Cancer stages III and IV. We therefore recommend the routine use of SLNE for tumor staging and stratification for adjuvant therapy of patients with stage I and II malignant melanoma. The authors have indicated no significant interest with commercial supporters. [source] Positron emission tomography and its use to image the occupancy of drug binding sitesDRUG DEVELOPMENT RESEARCH, Issue 2 2003S. John Gatley Abstract The development of positron emission tomography (PET) and the ability to synthesize compounds labeled with the short-lived positron emitters 11C and 18F has made possible the imaging and quantification of drug binding sites in the human body. By conducting PET studies with an appropriate radioligand before and after treatment with a drug, the fraction of the total number of binding sites that is occupied by the drug (the "occupancy" of the site) can often be determined. To the extent that occupancy is a good indicator of pharmacological activity, such PET experiments can aid the development of drug dosage regimens. Some of the general issues involved in PET studies of drug occupancy are discussed. There have been many such studies involving antipsychotic drugs and dopamine D2 receptor radioligands. Since neuroleptics have been extensively reviewed elsewhere, only the major findings are discussed here. Other binding sites (and drug classes) in the dopamine system to which this methodology has been applied include: the dopamine transporter (stimulant drugs) and monoamine oxidase A and B (antidepressant drugs). Occupancy studies are also possible for many drug targets beyond the dopamine system. Drug Dev. Res. 59:194,207, 2003. © 2003 Wiley-Liss, Inc. [source] Molecular and diffusion tensor imaging of epileptic networksEPILEPSIA, Issue 2008Aimee F. Luat Summary Several studies have shown that seizure-induced cellular and molecular changes associated with chronic epilepsy can lead to functional and structural alterations in the brain. Chronic epilepsy, when medically refractory, may be associated with an expansion of the epileptic circuitry to involve complex interactions between cortical and subcortical neuroanatomical substrates. Progress in neuroimaging has led not only to successful identification of epileptic foci for surgical resection, but also to an improved understanding of the functional and microstructural changes in long-standing epilepsy. Positron emission tomography (PET), functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) are all promising tools that can assist in elucidating the underlying pathophysiology in chronic epilepsy. Studies using PET scanning have demonstrated dynamic changes associated with the evolution from acute to chronic intractable epilepsy. Among these changes are data to support the existence of secondary epileptogenesis in humans. MRI with DTI is a powerful tool which has the ability to characterize microstructural abnormalities in epileptic foci, and to demonstrate the white matter fibers and tracts participating in the epileptic network. In this review, we illustrate how PET and DTI can be applied to depict the functional and microstructural alterations associated with chronic epilepsy. [source] Imaging of acetylcholine esterase activity in brainstem nuclei involved in regulation of sleep and wakefulnessEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2007C. Eggers Positron emission tomography with 11C- N -methyl-4-piperidyl-acetate (MP4A) was applied in eight healthy volunteers and two patients with mild Alzheimer's disease (AD) to assess acetylcholine esterase (AChE) activity in magnetic resonance imaging-identified brainstem nuclei. Uptake ratios in lateral dorsal tegmental and pedunculopontine nuclei relative to cerebellum yielded reproducible values for the AChE activity in controls and reduced values in AD, more marked in a patient with complaints of disturbed sleep. Cortical AChE activity was related to the extent of cognitive impairment which was more severe in the AD patient without sleep disturbance. This preliminary observational study demonstrates the feasibility to image and assess AChE activity in small nuclei of the brain stem. This approach may be helpful to investigate the interaction of various nuclei in the complex network regulating sleep and wakefulness in representative patient groups with documented sleep disturbance. [source] Positron emission tomography and magnetic resonance imaging in spinocerebellar ataxia type 2: a study of symptomatic and asymptomatic individualsEUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2005A. Inagaki Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disorder characterized as an expanded CAG trinucleotide repeats in SCA2 gene resulting in abnormal polyglutamine sequence. We used positron emission tomography (PET) and magnetic resonance imaging (MRI) to clarify metabolic and atrophic changes of the brain in two symptomatic and three asymptomatic individuals who were genetically confirmed for SCA2. PET revealed decreased glucose metabolism in both patients and two of the three asymptomatic carriers in the cerebellum, pons, or both. No PET abnormality was found in the remaining one carrier who had only a very mildly expanded CAG repeat. MRI showed cerebellar and/or pontine atrophic changes in both patients and one of three carriers. The present study suggest that hypometabolism and atrophy of the cerebellum and pons may occur years before the clinical onset of SCA2. PET and MRI may be useful in the early detection of subclinical brain changes associated with SCA2. [source] A survey of neuroimaging research in European neurological departmentsEUROPEAN JOURNAL OF NEUROLOGY, Issue 2 2001K. Herholz In the international neurological literature, neuroimaging research plays an important role. Neuroimaging techniques are also of steadily increasing importance for clinical diagnosis and treatment monitoring. Therefore, neuroimaging research activities were surveyed by a questionnaire, which was completed by 100 neurological centres across Europe. It showed that most groups use magnetic resonance imaging (MRI), fMRI, computerized tomography (CT) and single photon emission computerized tomography (SPECT). Positron emission tomography (PET) and ultrasound are also employed by nearly half of the centres. Neuroimaging research involves co-operation amongst typically five to 10 disciplines. Cerebrovascular disease, dementia, cognitive disorders, epilepsy, movement disorders, brain tumours and multiple sclerosis are frequently being studied. Many groups rely on small budgets, have few full-time scientists and limited access to expensive resources. There is little exchange of scientists amongst laboratories. It was felt that funding and co-operation needed improvement in order to maintain a high standard in neuroimaging research. [source] Positron emission tomography in surveillance of head and neck squamous cell carcinoma after definitive chemoradiotherapyHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 4 2009Yi-Fen Wang MD Abstract Background. We assessed the role of 18F-fluoro-deoxy-glucose positron emission tomography (PET) in detecting head and neck squamous cell carcinoma (HNSCC) after definitive chemoradiotherapy (CRT). Methods. A prospective study presented 80 PET before and after CRT for 44 patients, including 44 first-time post-CRT scans performed between 12 and 17 weeks after radiotherapy completion, as well as 10 repeated scans in the subsequent follow-up. PET interpretations were compared with clinicopathologic outcomes. Results. PET demonstrated better performance than CT in post-CRT surveillance. Considering all 54 post-CRT PET scans, sensitivity for detecting primary tumors was 100%, specificity 93%, positive predictive value (PPV) 80%, and negative predictive value (NPV) 100%. For cervical diseases, sensitivity was 100%, specificity 98%, PPV 92%, and NPV 100%. For distant metastases, sensitivity was 100%, specificity 98%, PPV 86%, and NPV 100%. Conclusions. Negative PET readings were reliable for predicting free of HNSCC and helpful for selected patients in post-CRT surveillance. © 2009 Wiley Periodicals, Inc. Head Neck, 2009 [source] FDG PET studies during treatment: Prediction of therapy outcome in head and neck squamous cell carcinomaHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 2 2002Eva Brun MD Background Positron emission tomography (PET) provides metabolic information of tissues in vivo. The purpose of this study was to assess the value of PET with 2-[18 F] fluoro-2-deoxy- D -glucose (FDG) in prediction of therapy outcome (tumor response, survival, and locoregional control) in locally advanced HNSCC. Methods Between 1993 and 1999 47 patients underwent PET before (PET1) and after (PET2) 1 to 3 weeks of radical treatment with evaluation of metabolic rate (MR) and standardized uptake value (SUV) of FDG. All patients received radiotherapy, and 10 also received neoadjuvant chemotherapy. Median follow-up time was 3.3 years. Results Low and high MR FDG at PET2, with median value as cutoff, was associated with complete remission in 96% and 62% (p = .007), with 5-year overall survival in 72% and 35% (p = .0042) and with local control in 96% and 55% (p = .002), respectively. Conclusions FDG PET in the early phase of treatment of HNSCC is associated with tumor response, survival, and local control. © 2002 John Wiley & Sons, Inc. [source] Evidence of thymic reconstitution after highly active antiretroviral therapy in HIV-1 infectionHIV MEDICINE, Issue 2 2004G Hardy Objectives We aimed to provide evidence of thymic reconstitution after highly active antiretroviral therapy (HAART) in HIV-1 infected patients and to correlate this with the restoration of peripheral naïve T cells. Methods Positron emission tomography (PET) enables definitive evidence of thymic activity, indicating functional potential. In this case study, a single patient who initiatiated HAART demonstrated reconstitution of the naïve T-cell pool and underwent thymic PET scans at baseline and 2 and 6 months following initiation of therapy. Two patients who failed to demonstrate such reconstitution acted as controls. These patients (mean age 27 years) had chronic HIV infection with low CD4 T-cell counts (mean 82, range 9,160 cells/,L blood). Increased function of the thymus visualized by PET was correlated with phenotypic changes in CD4 and CD8 T cells in the periphery measured by flow cytometry, and with numbers of recent thymic emigrants measured by quantification of the numbers of T-cell receptor excision circles (TRECs) in peripheral cells. Results In one patient, clear correlations could be drawn between visible activity within the thymus, as measured by increased [F18]fluorodeoxyglucose (FDG) uptake, and regeneration of naïve CD4 (CD45RA/CD62L) T cells, increased numbers of CD4 T cells, controlled viraemia and increased numbers of recent thymic emigrants. A second patient displayed no increase in peripheral CD4 count and no increase in thymic activity. The third patient elected to stop therapy following the 2-month time point. Conclusions The use of PET suggests that thymic activity may increase after HAART, indicating that the thymus has the potential to be functional even in HIV-1 infected persons with low CD4 T-cell counts. [source] Prefrontal cortex activity is reduced in gambling and nongambling substance users during decision-making,HUMAN BRAIN MAPPING, Issue 12 2007Jody Tanabe Abstract Objective: Poor decision-making is a hallmark of addiction, whether to substances or activities. Performance on a widely used test of decision-making, the Iowa Gambling Task (IGT), can discriminate controls from persons with ventral medial frontal lesions, substance-dependence, and pathological gambling. Positron emission tomography (PET) studies indicate that substance-dependent individuals show altered prefrontal activity on the task. Here we adapted the IGT to an fMRI setting to test the hypothesis that defects in ventral medial and prefrontal processing are associated with impaired decisions that involve risk but may differ depending on whether substance dependence is comorbid with gambling problems. Method: 18 controls, 14 substance-dependent individuals (SD), and 16 SD with gambling problems (SDPG) underwent fMRI while performing a modified version of the IGT. Result: Group differences were observed in ventral medial frontal, right frontopolar, and superior frontal cortex during decision-making. Controls showed the greatest activity, followed by SDPG, followed by SD. Conclusion: Our results support a hypothesis that defects in ventral medial frontal processing lead to impaired decisions that involve risk. Reductions in right prefrontal activity during decision-making appear to be modulated by the presence of gambling problems and may reflect impaired working memory, stimulus reward valuation, or cue reactivity in substance-dependent individuals. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source] Odor processing in multiple chemical sensitivityHUMAN BRAIN MAPPING, Issue 3 2007Lena Hillert Abstract Multiple chemical sensitivity (MCS) is characterized by somatic distress upon exposure to odors. As in other idiopathic environmental intolerances, the mechanisms behind the reported hypersensitivity are unknown. Using the advantage of the well-defined trigger (odor), we investigated whether subjects with MCS could have an increased odor-signal response in the odor-processing neuronal circuits. Positron emission tomography (PET) activation studies with several different odorants were carried out in 12 MCS females and 12 female controls. Activation was defined as a significant increase in regional cerebral blood flow (rCBF) during smelling of the respective odorant compared to smelling of odorless air. The study also included online measurements of respiratory frequency and amplitude and heart rate variations by recording of R wave intervals (RR) on the surface electrocardiogram. The MCS subjects activated odor-processing brain regions less than controls, despite the reported, and physiologically indicated (decreased RR interval) distress. In parallel, they showed an odorant-related increase in activation of the anterior cingulate cortex and cuneus-precuneus. Notably, the baseline rCBF was normal. Thus, the abnormal patterns were observed only in response to odor signals. Subjects with MCS process odors differently from controls, however, without signs of neuronal sensitization. One possible explanation for the observed pattern of activation in MCS is a top-down regulation of odor-response via cingulate cortex. Hum. Brain Mapp, 2007. © 2006 Wiley-Liss, Inc. [source] Diagnostic value of FDG-PET in recurrent colorectal carcinoma: A meta-analysisINTERNATIONAL JOURNAL OF CANCER, Issue 1 2009Chenpeng Zhang Abstract Accurate detection of recurrent colorectal carcinoma remains a diagnostic challenge. The purposes of this study were to evaluate the diagnostic value of Positron emission tomography (PET) using fluor-18-deoxyglucose (FDG) in recurrent colorectal carcinoma with a meta-analysis. All the published studies in English relating the diagnostic value of FDG-PET in the detection of recurrent colorectal carcinoma were collected. Methodological quality of the included studies was evaluated. Pooled sensitivity, specificity and diagnostic odds ratio and SROC (summary receiver operating characteristic curves) were obtained by the statistical software. Twenty-seven studies were included in the meta-analysis. The pooled sensitivity and specificity for FDG-PET detecting distant metastasis or whole body involvement in recurrent colorectal carcinoma were 0.91 (95% CI 0.88,0.92) and 0.83 (95% CI 0.79,0.87), respectively. The pooled sensitivity and specificity for FDG-PET detecting hepatic metastasis were 0.97 (95% CI 0.95,0.98) and 0.98 (95% CI 0.97,0.99). The pooled sensitivity and specificity for pelvic metastasis or local regional recurrence were 0.94 (95% CI 0.91,0.97) and 0.94 (95% CI 0.92,0.96). FDG-PET is valuable for the assessment of recurrent colorectal carcinoma. © 2008 Wiley-Liss, Inc. [source] Brain dopamine is associated with eating behaviors in humansINTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 2 2003Nora D. Volkow Abstract Objective Eating behavior in humans is influenced by variables other than just hunger-satiety including cognitive restraint, emotional distress, and sensitivity to food stimuli. We investigate the role of dopamine (DA), a neurotransmitter involved with food motivation, in these variables. Methods We used the Dutch Eating Behavior Questionnaire (DEBQ) to measure Restraint, Emotionality, and Externality in 10 subjects. We correlated DEBQ scores with brain DA levels. Positron emission tomography and {11C}raclopride uptake were used to measure baseline D2 receptors (neutral stimulation) and to assess changes in extracellular DA to food stimulation (display of food). Results Restraint was correlated with DA changes with food stimulation (higher restraint, greater responsivity), emotionality was negatively correlated with baseline D2 receptors (higher emotionality, lower D2 receptors), whereas externality was not. These correlations were significant in the dorsal but not in the ventral striatum. Discussion These results provide evidence that DA in the dorsal striatum is involved with the restraint and emotionality components regulating eating behavior and that these two dimensions reflect different neurobiologic processes. © 2003 by Wiley Periodicals, Inc.Int J Eat Disord 33: 136,142, 2003. [source] Gastrointestinal: Positron emission tomography scans and colonic polypsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 12 2004KG TAN [source] Synthesis of (R)- and (S)-[O-methyl - 11C]N -[2-[3-(2-cyano-phenoxy)-2-hydroxy-propylamino]-ethyl]- N,-(4-methoxy-phenyl)-urea as candidate high affinity ,1 -adrenoceptor PET radioligandsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 10 2005Stefan Wagner Abstract Molecular imaging and quantification of myocardial ,1 -adrenoceptor (AR) rather than total , -AR density is of great clinical interest since cardiac biopsy studies suggest that myocardial ,1 -AR density is reduced in patients with chronic heart failure whereas cardiac ,2 -AR density may vary. Positron emission tomography (PET), with appropriate radioligands, offers the possibility to assess , -AR density non-invasively in humans. However, no PET radioligand for the selective imaging of cardiac ,1 -ARs is clinically available. Here some derivatives of the well characterized ,1 -AR selective antagonist, ICI 89,406, namely the enantiomers of N -[2-[3-(2-cyano-phenoxy)-2-hydroxy-propylamino]-ethyl]- N,-(4-hydroxy-phenyl)-urea (5a and 5b) were synthesized and evaluated in vitro. The (R)-isomer 5a was more ,1 -selective but has lower affinity than its (S)-enantiomer 5b (,1 -AR selectivity: 6100 vs 1240; ,1 -affinity: K1 = 0.288 nM vs K1 = 0.067 nM). Etherification of the analogous desmethyl precursors, 5e and 5f, respectively, with [11C]iodomethane gave 11C-labelled versions of 5a and 5b, namely 5g and 5h, in 44 ± 5% radiochemical yield (decay-corrected) and 97.4 ± 1.3% radiochemical purity with specific radioactivities of 26.4 ± 9.4 GBq/µmol within 41.2 ± 3.4 min from the end of bombardment (n = 14). 5g and 5h are now being evaluated as candidate radioligands for myocardial ,1 -ARs. Copyright © 2005 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||