Search results for "Positron"
showing 10 items of 1346 documents
The applicability of SRTM in [18F]fallypride PET investigations: Impact of scan durations
2011
The high-affinity radioligand [18F]fallypride (FP) is frequently used for quantification of striatal/extrastriatal D2/3 receptors and the receptor occupancies of antipsychotics (APs). Its 110 minutes half-life allows long scan durations. However, the optimum scan duration is a matter of debate. This investigation focuses on scan-duration-related effects on simplified reference tissue model (SRTM) results and the time point of transient equilibrium in a large sample of dynamic FP positron emission tomography (PET) scans. Fifty drug-free and 50 AP-treated subjects underwent FP-PET scans (180 minutes scan duration). The binding potential ( BPND) of the putamen, thalamus, and temporal cortex w…
Dopamine D2/D3 receptor availability and venturesomeness.
2011
The construct of impulsivity is considered as a major trait of personality. There is growing evidence that the mesolimbic dopamine system plays an important role in the modulation of impulsivity and venturesomeness, the two key components within the impulsivity-construct. The aim of the present study was to explore an association between trait impulsivity measured with self-assessment and the dopaminergic neurotransmission as measured by positron emission tomography (PET) in a cohort of healthy male subjects. In vivo D2/D3 receptor availability was determined with [(18)F]fallypride PET in 18 non-smoking healthy subjects. The character trait impulsivity was measured using the Impulsiveness-V…
The unpleasantness of tonic pain is encoded by the insular cortex
2005
Objective: Muscle pain differs from skin pain with respect to quality, accuracy of localization, and unpleasantness. This study was conducted to identify the brain regions associated with the affective-motivational component of tonic skin and muscle pain. Methods: Forty healthy volunteers were investigated in three groups with different F-18 fluorodeoxyglucose PET activation scans. A verbal rating scale (VRS) was used to quantify pain intensity and unpleasantness. One group was investigated during painful infusion of an acidified phosphate buffer (pH 5.2) into either muscle or skin for 30 minutes. Muscle and skin infusions were adjusted to achieve pain intensity rating of VRS = 40. The seco…
Time Course of 5-HT2A Receptor Occupancy in the Human Brain after a Single Oral Dose of the Putative Antipsychotic Drug MDL 100,907 Measured by Posit…
1997
MDL 100,907 is a potent and selective antagonist of 5-HT2A serotonin receptors. Animals studies suggest that MDL 100,907 may behave as an atypical antipsychotic drug. Positron emission tomograph (PET) using [11C]NMSP as the radiotracer was used to define the time course of 5-HT2 receptor occupancy in the human frontal cerebral cortex after a single oral dose of MDL 100,907 (10 or 20 mg) in nine healthy subjects. After the baseline scan each subject was studied three times post dosing at various time points. 5-HT2 occupancies were in the range of 70 and 90% after each dose. While the occupancy remains in this range over 24 hours after 20 mg MDL 100,907, it decreases by about 20% at 24 hours …
Metabolic and structural connectivity within the default mode network relates to working memory performance in young healthy adults.
2012
Abstract Studies of functional connectivity suggest that the default mode network (DMN) might be relevant for cognitive functions. Here, we examined metabolic and structural connectivity between major DMN nodes, the posterior cingulate (PCC) and medial prefrontal cortex (MPFC), in relation to normal working memory (WM). DMN was captured using independent component analysis of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) data from 35 young healthy adults (27.1 ± 5.1 years). Metabolic connectivity, a correlation between FDG uptake in PCC and MPFC, was examined in groups of subjects with (relative to median) low (n = 18) and high (n = 17) performance on digit span backward te…
Evidence for modulation of opioidergic activity in central vestibular processing: A [(18)F] diprenorphine PET study.
2009
Animal and functional imaging studies had identified cortical structures such as the parieto‐insular vestibular cortex, the retro‐insular cortex, or the anterior cingulate cortex belonging to a vestibular cortical network. Basic animal studies revealed that endorphins might be important transmitters involved in cerebral vestibular processing. The aim of the present study was therefore to analyse whether the opioid system is involved in vestibular neurotransmission of humans or not. Changes in opioid receptor availability during caloric air stimulation of the right ear were studied with [(18)F] Fluoroethyl‐diprenorphine ([(18)F]FEDPN) PET scans in 10 right‐handed healthy volunteers and compa…
Age-dependent decline of steady state dopamine storage capacity of human brain: an FDOPA PET study.
2010
Conventional indices of the utilization of FDOPA in living human brain have not consistently revealed important declines in dopamine function with normal aging. However, most methods of kinetic analysis have assumed irreversible trapping of decarboxylated FDOPA metabolites in brain, an assumption that is violated even in PET recordings of short duration. Therefore, we have developed methods for the calculation of steady-state storage of FDOPA together with its decarboxylated metabolites (V(d), mlg(-1)), based upon improved kinetic analysis of 120-min emission recordings. In a group of 28 normal male subjects, of age ranging from 23 to 73 years, the magnitude of V(d) in the striatum and in e…
Response-guided ABVD chemotherapy plus involved-field radiation therapy for intermediate-stage Hodgkin lymphoma in the pre-positron emission tomograp…
2009
Abstract Purpose In the pre—positron emission tomography era, the Gruppo Italiano Studio Linfomi (GISL) investigated the feasibility and efficacy of a treatment based on a response-tailored number of doxorubicin/bleomycin/vinblastine/dacarbazine (ABVD) courses in 218 intermediate-stage Hodgkin lymphoma patients. Patients and Methods Patients with stage I/II showing at least one adverse prognostic factor and stage IIIA without adverse prognostic factors were recruited. Treatment included a first step of 3 ABVD courses, followed by an early-restaging. Patients in CR/CRu received 1 additional ABVD cycle, patients in PR received 3 more ABVD, and nonresponder patients went off study. Involved-fi…
Dual Diagnostic Role of 123I-MIBG Scintigraphy in Inverted-Takotsubo Pattern Cardiomyopathy
2015
We highlight the dual role of I-MIBG scintigraphy in inverted-Takotsubo pattern cardiomyopathy, the diagnosis of which is sometimes challenging: Firstly, I-MIBG scintigraphy can show myocardial sympathetic dysfunction (low I-MIBG uptake) in the hypokinetic basal segments, sparing the left ventricle apex. It is helpful in the imaging diagnosis of inverted-Takotsubo pattern cardiomyopathy and confirms that acute dysfunction of myocardial sympathetic nerve endings occurs with this cardiomyopathy. Secondly, I-MIBG scintigraphy is an accurate imaging examination to detect and localize pheochromocytoma; it can help in the search for an endogenous cause of this adrenergic stress-related cardiomyop…
Baseline [18F]-FDOPA kinetics are predictive of haloperidol-induced changes in dopamine turnover and cognitive performance: A positron emission tomog…
2007
The telencephalic dopamine innervations contribute to the modulation of cognitive processing. However, the relationship between cognitive effects of D(2/3)-receptor antagonism and dopamine transmission is not described in healthy subjects. We therefore tested effects of acute haloperidol (5 mg/d over 3 days) on continuous performance task (CPT) performance and 6-[(18)F]-fluoro-l-DOPA (FDOPA) PET parameters. Nine physically and mentally healthy male men performed two FDOPA-PET scans including arterial plasma withdrawal. Over 3 days before the second scan, all subjects were treated with 5 mg/d haloperidol orally. Using our novel steady-state analysis, we calculated the intrinsic rate of the c…