C-11 DIPRENORPHINE BINDING IN HUNTINGTONS-DISEASE - A COMPARISON OF REGION OF INTEREST ANALYSIS WITH STATISTICAL PARAMETRIC MAPPING

We compare region of interest (ROI) analytical approaches with statist ical parametric mapping (SPM) of C-11-diprenorphine positron emission tomography findings in five patients with Huntington's disease (HD) an d nine age-matched controls. The ROI were placed on caudate, putamen, and an occipital reference area, Ratios of striatal-occipital uptake f rom averaged static images centered at 60 minutes showed a mean 20% re duction in caudate (P = 0.034) and 15% reduction in putamen (P = 0.095 ) receptor binding in the HD patients. Dynamic data from caudate and p utamen ROI, together with a plasma tracer input function, were analyze d using spectral analysis to give regional impulse response functions. Regional data at 60 minutes after impulse showed a mean 29% decrease in caudate (P = 0.006) and 23% decrease in putamen (P = 0.029) opioid binding in the HD cohort. Parametric images of tracer binding also wer e produced with spectral analysis on a voxel basis. The images of the unit impulse response function at 60 minutes showed a mean 31% decreas e in caudate (P = 0.005) and a 26% decrease in putamen binding (P = 0. 011) in HD. The voxel-based parametric images were transformed into st andard stereotactic space, and a between-group comparison (patient ver sus controls) was performed with SPM. This approach revealed symmetric al decreases in caudate (peak 40% decrease, z score = 4.38) and putame n opioid binding (peak 24% decrease, z score = 4.686) with additional nonhypothesized changes in cingulate, prefrontal, and thalamic areas. The significance and precision of changes measured with spectral analy sis applied to dynamic data sets were superior to ROI-based ratio anal ysis on static images. The SPM replicated the striatal reductions in o pioid binding in HD and detected additional nonpredicted changes. This study suggests that SPM is a valid alternative to conventional ROI an alytical approaches for determining binding changes with positron emis sion tomography and may have advantages over region-based analyses in exploratory studies.