Poster E103, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Dopamine D2/3 receptor binding with [11C]raclopride in extrastriatal regions show good to excellent six month test-retest reliability
Lars Jonasson1, Nina Karalija1, Jan Axelsson1, Katrine Riklund1, Lars Nyberg1, CJ Boraxbekk1,2; 1Umeå University, Sweden, 2Copenhagen University Hospital Hvidovre, Denmark
It has previously been assumed that binding of the reversible ligand [11C]raclopride to human dopamine D2/3 receptors (D2/3R) in extrastriatal areas can not be measured reliably. Recently, Alakurtti and colleagues (2015) showed good 5-weeks test-retest reliability with [11C]raclopride in extrastriatal regions using the dedicated brain positron emission tomograph (PET), Siemens ECAT HRRT. Here we present evidence that reliable measurements of [11C]raclopride in extrastriatal regions can be achieved also using a PET/CT scanner for whole-body acquisition, and with data reconstructed using a high-resolution ordered-subsets maximization algorithm. A control sample from an intervention study, n = 28, 64-78 years, were scanned twice, 6 months in-between scans. Intraclass correlation coefficients (ICC) in striatal regions were excellent; limbic, associative, and sensorimotor striatum (0.91-0.94) with a test-retest variability (VAR) between 3.8 and 4.6%. Reliability in extrastriatal regions were good to excellent, albeit more variable, with thalamus, hippocampus, dorsolateral prefrontal cortex, inferior frontal gyrus, superior frontal gyrus and anterior cingulate cortex showing ICCs between 0.89-0.91, and VAR (4.1-18.6%), and orbitofrontal cortex and amygdala both showing an ICC of 0.69 and VAR (8.7-9.6%). The present data indicates that reliable estimates of D2/3R can be achieved in extrastriatal regions using [11C]raclopride. This is an important finding as [11C]raclopride is a common ligand used to image D2/3R, and that dedicated brain PET/CT scanners are not necessary to measure reliably in extrastriatal regions. Our results converge with other recent findings to suggest that extrastriatal D2/3R can be investigated with [11C]raclopride.
Topic Area: METHODS: Neuroimaging