Showing papers by "Swen Hesse published in 2012"

Imaging of the brain serotonin transporters (SERT) with 18F-labelled fluoromethyl-McN5652 and PET in humans

Abstract: [11C]DASB is currently the most frequently used highly selective radiotracer for visualization and quantification of central SERT. Its use, however, is hampered by the short half-life of 11C, the moderate cortical test–retest reliability, and the lack of quantifying endogenous serotonin. Labelling with 18F allows in principle longer acquisition times for kinetic analysis in brain tissue and may provide higher sensitivity. The aim of our study was to firstly use the new highly SERT-selective 18F-labelled fluoromethyl analogue of (+)-McN5652 ((+)-[18F]FMe-McN5652) in humans and to evaluate its potential for SERT quantification. The PET data from five healthy volunteers (three men, two women, age 39 ± 10 years) coregistered with individual MRI scans were semiquantitatively assessed by volume-of-interest analysis using the software package PMOD. Rate constants and total distribution volumes (V T) were calculated using a two-tissue compartment model and arterial input function measurements were corrected for metabolite/plasma data. Standardized uptake region-to-cerebellum ratios as a measure of specific radiotracer accumulation were compared with those of a [11C]DASB PET dataset from 21 healthy subjects (10 men, 11 women, age 38 ± 8 years). The two-tissue compartment model provided adequate fits to the data. Estimates of total distribution volume (V T) demonstrated good identifiability based on the coefficients of variation (COV) for the volumes of interest in SERT-rich and cortical areas (COV V T <10%). Compared with [11C]DASB PET, there was a tendency to lower mean uptake values in (+)-[18F]FMe-McN5652 PET; however, the standard deviation was also somewhat lower. Altogether, cerebral (+)-[18F]FMe-McN5652 uptake corresponded well with the known SERT distribution in humans. The results showed that (+)-[18F]FMe-McN5652 is also suitable for in vivo quantification of SERT with PET. Because of the long half-life of 18F, the widespread use within a satellite concept seems feasible.

[123I]FP-CIT SPECT in atypical degenerative parkinsonism

Abstract: One of the most widely used techniques to support the clinical diagnosis of Parkinson’s disease is the SPECT scan with [123I]FP-CIT. This tracer binds reversibly and visualizes the striatal presynaptic dopamine transporters. Several uncertainties remain on the value of [123I]FP-CIT and SPECT in atypical degenerative parkinsonian syndromes. In this concise review, we discuss the contribution of SPECT and [123I]FP-CIT in supporting the clinical diagnosis of Parkinson’s disease and their role in the differential diagnosis of Parkinson’s disease and atypical degenerative parkinsonism. The chemistry, pharmacodynamics and pharmacokinetics of [123I]FP-CIT are also discussed.

PET Imaging of Dementia

Abstract: In the medical dictionary, dementia is defined in the following way: “Dementia is a loss of mental ability severe enough to interfere with normal activities of daily living, lasting more than six months, not present since birth, and not associated with a loss or alteration of consciousness”. Dementia is usually caused by neurodegenerative diseases, e.g., Alzheimer’s disease (AD), frontotemporal lobar degeneration (FTLD), dementia with Lewy bodies (DLB) or vascular lesions. However, some psychiatric syndromes, e.g., severe major depression (MD) and severe metabolic abnormalities, e.g., serious hypothyroidism, can mimic dementia. Specific organic disorders, e.g., multiple sclerosis, AIDS, prolonged abuse of alcohol or other drugs, may also cause dementias. In the daily routine of a positron-emission tomography (PET) center, patients with dementia or questionable dementia caused by neurodegenerative disorders have been examined.