The applicability of SRTM in 18 Ffallypride PET investigations: Impact of scan durations

Ingo Vernaleken, Lisa Peters, Mardjan Raptis, Robert Lin, Hans Georg Buchholz, Yun Zhou, Oliver Winz, Frank Rösch, Peter Bartenstein, Dean F. Wong, Wolfgang M. Schäfer, Gerhard Gründer

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


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 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 12129.6 minutes. The transient equilibrium occurred much earlier in the extrastriatal regions or under AP treatment. Stepwise scan shortening caused BPND 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. [18F]fallypride scan durations of 180 minutes reliably reach equilibrium even in D2/3-receptor-rich regions. Moderate reductions in FP scan durations only caused small changes to SRTM results even in receptor-rich regions. Apparently, the D2/3 receptor occupancy results of APs, especially preferential extrastriatal binding observations, are not relevantly biased by inappropriate scan durations.

Original languageEnglish
Pages (from-to)1958-1966
Number of pages9
JournalJournal of Cerebral Blood Flow and Metabolism
Issue number9
StatePublished - Sep 2011


  • Equilibrium
  • [F]fallypride
  • positron emission tomography
  • scan duration
  • simplified reference tissue model


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