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Positron-emission Tomography (positron-emission + tomography)
Selected AbstractsNeocortical Temporal FDG-PET Hypometabolism Correlates with Temporal Lobe Atrophy in Hippocampal Sclerosis Associated with Microscopic Cortical DysplasiaEPILEPSIA, Issue 4 2003Beate Diehl Summary: ,Purpose: Medically intractable temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS), with or without cortical dysplasia (CD), is associated with atrophy of the hippocampal formation and regional fluorodeoxyglucose positron-emission tomography (FDG-PET) hypometabolism. The relation between areas of functional and structural abnormalities is not well understood. We investigate the relation between FDG-PET metabolism and temporal lobe (TL) and hippocampal atrophy in patients with histologically proven isolated HS and HS associated with CD. Methods: Twenty-three patients underwent en bloc resection of the mesial and anterolateral neocortical structures. Ten patients were diagnosed with isolated HS; 13 patients had associated microscopic CD. Temporal lobe volumes (TLVs) and hippocampal volumes were measured. Magnetic resonance imaging (MRI) and PET were co-registered, and regions of interest (ROIs) determined as gray matter of the mesial, lateral, and anterior temporal lobe. Results: All patients (HS with or without CD) had significant ipsilateral PET hypometabolism in all three regions studied (p < 0.0001). In patients with isolated HS, the most prominent hypometabolism was in the anterior and mesial temporal lobe, whereas in dual pathology, it was in the lateral temporal lobe. TLVs and hippocampal volumes were significantly smaller on the epileptogenic side (p < 0.05). The PET asymmetries ipsilateral/contralateral to the epileptogenic zone and TLV asymmetries correlated significantly for the anterior and lateral temporal lobes (p < 0.05) in the HS+CD group, but not in the isolated HS group. Mesial temporal hypometabolism was not significantly different between the two groups. Conclusions: Temporal neocortical microscopic CD with concurrent HS is associated with more prominent lateral temporal metabolic dysfunction compared with isolated HS in TL atrophy. Further studies are needed to confirm these findings and correlate the PET hypometabolic patterns with outcome data in patients operated on for HS with or without CD. [source] Molecular imaging in hereditary forms of parkinsonismEUROPEAN JOURNAL OF NEUROLOGY, Issue 4 2007M. C. Shih The development of in vivo molecular imaging to evaluate the dopamine (DA) system with positron-emission tomography and single photon emission computed tomography has been of key importance on monitoring in vivo nigrostriatal neuronal loss in Parkinson's disease (PD), mostly through assessments of pre- and post-synaptic DA receptors. The discoveries of genes related to hereditary forms of parkinsonism (PARK1, PARK2, PARK6, PARK7 and PARK8) have increased our understanding either of distinct subtypes of clinical expression in PD or its etiology. This article revises current data on molecular neuroimaging of genetic forms of parkinsonism comparing and contrasting its main features with the classical sporadic forms. Awareness of the spectrum variance in the genotype and its respective PD phenotype are useful to distinguish different pathophysiological mechanisms of PD. [source] F-18-fluoro-deoxy-glucose positron-emission tomography scanning in detection of local recurrence after radiotherapy for laryngeal/ pharyngeal cancerHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 11 2001Chris H. Terhaard MD Abstract Background The objective of this investigation was to determine whether F18-fluoro-deoxy-glucose (FDG) positron-emission tomography (PET) could differentiate between local recurrence and late radiation effects after radiotherapy for laryngeal/pharyngeal cancer. Methods In a prospective study of 75 patients (67 larynx, eight oro/hypopharynx), 160 laryngoscopies and 109 FDG PET scans were performed on the head and neck region. The mean follow-up time after the first FDG PET scan was 23 months (minimum 1 year). Results Local recurrence was diagnosed in 37 patients: 19 after the first biopsy and 18 after follow-up biopsies. For all of the negative initial FDG scans (27), the biopsies that were taken at the same time were negative and no recurrence was seen for at least 1 year. The first FDG scan was a true positive in 34 of 48 patients. In 12 of the 14 patients with false-positive results, FDG scans were repeated; a decreased FDG uptake was found in 9 of the 12. The sensitivity and specificity of the first scan were respectively 92% and 63%; including subsequent FDG scans, the rates were 97% and 82%, respectively. Conclusions When a local recurrence is suspected after radiotherapy for cancer of the larynx/pharynx, an FDG PET scan should be the first diagnostic step. No biopsy is needed if the scan is negative. If the scan is positive and the biopsy negative, a decreased FDG uptake measured in a follow-up scan indicates that a local recurrence is unlikely. © 2001 John Wiley & Sons, Inc. Head Neck 23: 933,941, 2001. [source] Intensity modulation of TMS-induced cortical excitation: Primary motor cortexHUMAN BRAIN MAPPING, Issue 6 2006Peter T. Fox Abstract The intensity dependence of the local and remote effects of transcranial magnetic stimulation (TMS) on human motor cortex was characterized using positron-emission tomography (PET) measurements of regional blood flow (BF) and concurrent electromyographic (EMG) measurements of the motor-evoked potential (MEP). Twelve normal volunteers were studied by applying 3 Hz TMS to the hand region of primary motor cortex (M1hand). Three stimulation intensities were used: 75%, 100%, and 125% of the motor threshold (MT). MEP amplitude increased nonlinearly with increasing stimulus intensity. The rate of rise in MEP amplitude was greater above MT than below. The hemodynamic response in M1hand was an increase in BF. Hemodynamic variables quantified for M1hand included value-normalized counts (VNC), intensity (z-score), and extent (mm3). All three hemodynamic response variables increased nonlinearly with stimulus intensity, closely mirroring the MEP intensity-response function. VNC was the hemodynamic response variable which showed the most significant effect of TMS intensity. VNC correlated strongly with MEP amplitude, both within and between subjects. Remote regions showed varying patterns of intensity response, which we interpret as reflecting varying levels of neuronal excitability and/or functional coupling in the conditions studied. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc. [source] Peptide-based radiopharmaceuticals: Future tools for diagnostic imaging of cancers and other diseasesMEDICINAL RESEARCH REVIEWS, Issue 3 2004S.M. Okarvi Abstract An Erratum has been published for this article in Medicinal Research Reviews 2004;24:685,686. Small synthetic receptor-binding peptides are the agents of choice for diagnostic imaging and radiotherapy of cancers due to their favorable pharmacokinetics. Molecular modification techniques permit the synthesis of a variety of bioactive peptides with chelating groups, without compromising biological properties. Various techniques have been developed that allow efficient and site-specific labeling of peptides with clinically useful radionuclides such as 99mTc, 123I, 111In, and 18F. Among them, 99mTc is the radionuclide of choice because of its excellent chemical and imaging characteristics. Recently, many 99mTc-labeled peptides have proven to be useful imaging agents. Beside 99mTc-labeled peptides, several peptides radiolabeled with 111In and 123I have been prepared and characterized. In addition, 18F-labeled peptides hold clinical potential due to their ability to quantitatively detect and characterize a variety of human diseases using positron-emission tomography. The availability of this wide range of peptides labeled with different radionuclides offers multiple diagnostic and therapeutic applications. Various receptors are over-expressed in particular tumor types and peptides binding to these receptors can be used to visualize tumor lesions scintigraphically. Thus, radiolabeled peptides have potential use as carriers for the delivery of radionuclides to tumors, infarcts, and infected tissues for diagnostic imaging and radiotherapy. Many radiolabeled peptides are currently under investigation to determine their potential as imaging agents. These peptides are designed mainly for thrombus, tumor, and infection/inflammation imaging. This article presents recent developments in small synthetic peptides for imaging of thrombosis, tumors, and infection/inflammation. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 357,397, 2004 [source] Positron-emission Tomography Used to Diagnose Tuberculosis in a Renal Transplant PatientAMERICAN JOURNAL OF TRANSPLANTATION, Issue 1 2002Neville Kukreja We describe the case of a 22-year-old Portuguese renal transplant patient whose post-transplant course was complicated by prolonged delayed graft function and pyrexia of unknown origin. Conventional imaging techniques were not definitive, but positron-emission tomography (PET) scanning identified abnormalities in the lung and mediastinum that led to a diagnostic biopsy demonstrating mycobacterial infection. [source] Evaluation of [11C]-choline positron-emission/computed tomography in patients with increasing prostate-specific antigen levels after primary treatment for prostate cancerBJU INTERNATIONAL, Issue 4 2007Ludwig Rinnab OBJECTIVE To evaluate [11C]-choline positron-emission tomography (PET)/computed tomography (CT) for detecting clinical recurrence after primary treatment for prostate cancer. PATIENTS AND METHODS In all, 50 patients with prostate cancer who had had initial therapy (radical prostatectomy in 40, external beam radiation in three and interstitial brachytherapy in seven) had PET/CT using [11C]-choline in the presence of an increased or increasing prostate-specific antigen (PSA) level. The mean (range) time to biochemical progression was 22 (2,136) months. Current PSA levels were determined in all patients at the time of examination. The results were correlated with the histopathology reports after targeted biopsy or surgery, and with the clinical follow-up. RESULTS The mean (median, range) PSA level in patients with positive PET/CT was 3.62 (2.42, 0.5,13.1) ng/mL, and that in patients with a negative scan was 0.90 (0.95, 0.41,1.40) ng/mL. PET/CT was positive in seven of 13 patients with a PSA level of <1.5 ng/mL, and histology was positive in this group in nine. In 17 patients with PSA levels of 1.5,2.5 ng/mL PET/CT was positive in all and the histology was positive in 13; in 11 men with a PSA level of 2.5,5 ng/mL PET/CT was positive in all 11 and the histology was positive in 10; in nine men with PSA levels of >5 ng/mL PET/CT identified all as positive and the histology was positive in eight. The sensitivity at a PSA level of <2.5 ng/mL of PET/CT for detecting recurrence was 91% (95% confidence interval, 71,99%) with a specificity of 50% (16,84)%. CONCLUSION [11C]-choline PET/CT seems to be useful for re-staging prostate cancer after curative therapy and with increasing PSA levels; this was verified by histological examination. We recommend this method at PSA levels of <2.5 ng/mL. [source] Fluorodeoxyglucose positron emission tomography studies in the diagnosis and staging of clinically advanced prostate cancerBJU INTERNATIONAL, Issue 1 2003J. Sung OBJECTIVE To determine the value of 18F-fluoro-2-deoxyglucose (FDG) positron-emission tomography (PET) studies in evaluating patients with advanced prostate cancer. PATIENTS AND METHODS FDG-PET scans were taken in 30 patients with advanced prostate cancer 1 h after an injection with 555 MBq of FDG. Patients were scanned from the base of the skull to the inguinal region (including the pelvis). They were also assessed by computed tomography (CT) of the abdomen and pelvis, and bone scintigraphy, to evaluate them for metastases. RESULTS Thirteen patients had locally extensive prostate cancer and 17 had metastatic disease. Twenty of the 30 patients were positive for radioisotope uptake in the prostate or extraprostatically. The patients with PET-detected prostate cancer were untreated (seven), treated hormonally while they had rising PSA levels (eight), or treated hormonally with a detectable but stable PSA (five). The remaining 10 patients were negative for FDG uptake in the prostate or any metastatic sites; these 10 patients were receiving hormone therapy, with undetectable PSA levels. CONCLUSION FDG-PET imaging is not a useful test in evaluating advanced prostate cancer in patients being treated and who have an undetectable PSA level. Staging of advanced prostate cancer may be enhanced by FDG-PET imaging in patients who are untreated, who have had an incomplete response to therapy, or who have a rising PSA level despite treatment. [source] Correlation of angiogenesis with 18F-FMT and 18F-FDG uptake in non-small cell lung cancerCANCER SCIENCE, Issue 4 2009Kyoichi Kaira L-[3- 18F]-,-methyltyrosine (18F-FMT) is an amino-acid tracer for positron-emission tomography (PET). We have conducted a clinicopathologic study to elucidate the correlation of angiogenesis with 18F-FMT and 2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) uptake in patients with non-small cell lung cancer (NSCLC). Thirty-seven NSCLC patients were enrolled in this study, and two PET studies with 18F-FMT and 18F-FDG were performed. Uptake of PET tracers was evaluated with standardized uptake value. Vascular endothelial growth factor (VEGF), CD31, CD34, L-type amino acid transporter 1 (LAT1) and Ki-67 labeling index of the resected tumors were analyzed by immunohistochemical staining, and correlated with the clinicopathologic variables and the uptake of PET tracers. The median VEGF rate was 45% (range, 10,78%). High expression was seen in 30 patients (81%, 30/37). VEGF expression was statistically associated with progressively growing microvessel count. VEGF showed a correlation with LAT1 expression (P = 0.04) and Ki-67 labeling index (P = 0.01). However, it showed no correlation with age, gender, disease stage, tumor size, and histology. Microvessel density (MVD) showed no correlation with any parameters. 18F-FMT and 18F-FDG uptake correlated significantly with VEGF (P < 0.0001, P = 0.026, respectively), whereas the correlation of 18F-FMT and VEGF was more meaningful. The present study demonstrated that the metabolic activity of primary tumors as evaluated by PET study with 18F-FMT and 18F-FDG is related to tumor angiogenesis and the proliferative activity in NSCLC. (Cancer Sci 2009; 100: 753,758) [source] Synthesis and Characterization of a C(6) Nucleoside Analogue for the in vivo Imaging of the Gene Expression of Herpes Simplex Virus Type-1 Thymidine Kinase (HSV1 TK)CHEMISTRY & BIODIVERSITY, Issue 3 2006Anass Johayem Abstract The synthesis and biological evaluation of ,6-(1,3-dihydroxyisobutyl)thymine' (DHBT; 1), which corresponds to 6-[3-hydroxy-2-(hydroxymethyl)propyl]-5-methylpyrimidine-2,4(1H,3H)-dione, is reported. DHBT (1) was designed as a new substrate for herpes simplex virus type-1 thymidine kinase (HSV1 TK). The compound was found to be exclusively phosphorylated by HSV1 TK, and to exhibit good binding affinity (Ki,=,35.3±1.3,,M). Cell-proliferation assays with HSV1-TK-transduced human osteosarcoma cells (143B-TK+-HSV1-WT) and with both human-thymidine-kinase-1-negative (143B-TK,) and non-transduced parental (MG-63) cells indicate that 1 is less cytotoxic than the standard drug Ganciclovir. Thus, DHBT (1) represents a promising precursor of a nontoxic reporter probe for the monitoring of HSV1 TK gene expression by means of positron-emission tomography (PET). [source] | |||||||||||||