Our MR-based attenuation correction method offers similar correction accuracy as offered by segmented CT. According to the specialists involved in the blind study, these differences do not affect the diagnostic value of the PET images.

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The high-affinity radioligand [18 F]fallypride (FP) is frequently used for quantification of striatal/ extrastriatal D 2/3 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 (BP ND ) of the putamen, thalamus, and temporal cortex were calculated using the SRTM and the transient equilibrium model. Furthermore, receptor occupancies were calculated for AP-treated patients. Transient equilibrium in the unblocked putamen occurred after 121 ± 29.6 minutes. The transient equilibrium occurred much earlier in the extrastriatal regions or under AP treatment. Stepwise scan shortening caused BP ND underestimations of 0.58% for the first 10-minute reduction (putamen, SRTM), finally reaching 5.76% after 1 hour scan-time reduction. We observed preferential extrastriatal AP binding irrespective of the analytical method. [18 F]fallypride scan durations of 180 minutes reliably reach equilibrium even in D 2/3 -receptor-rich regions. Moderate reductions in FP scan durations only caused small changes to SRTM results even in receptor-rich regions. Apparently, the D 2/3 receptor occupancy results of APs, especially preferential extrastriatal binding observations, are not relevantly biased by inappropriate scan durations.

The RT-3DE, in combination with a semi-automatic contour tracing algorithm, allows accurate determination of cardiac volumes and function compared with both manual tracing and CMRI. High repeatability suggests applicability of the method for the serial follow-up of patients with cardiac disease.