RESTING STATE RCBF MAPPING WITH SINGLE-PHOTON EMISSION TOMOGRAPHY ANDPOSITRON-EMISSION-TOMOGRAPHY - MAGNITUDE AND ORIGIN OF DIFFERENCES

Single-photon emission tomography (SPET), using technetium-99m hexamet hylpropylene amine oxime, and positron emission tomography (PET), usin g oxygen-15 butanol were compared in six healthy male volunteers with regard to the mapping of resting state regional cerebral blood flow (r CBF), A computerized brain atlas was utilized for 3D regional analyses and comparison of 64 selected and normalized volumes of interest (VOI s). The normalized mean rCBF values in SPET, as compared to PET, were higher in most of the Brodmann areas in the frontal and parietal lobes (4.8% and 8.7% respectively). The average differences were small in t he temporal (2.3%) and occipital (1.1%) lobes PET values were clearly higher in small VOIs like the thalamus (12.3%), hippocampus (12.3%) an d basal ganglia (9.9%). A resolution phantom study showed that the in- plane SPET/PET system resolution was 11.0/7.5 mm. In conclusion, SPET and PET data demonstrated a fairly good agreement despite the superior spatial resolution of PET, The differences between SPET and PET rCBF are mainly due to physiological and physical factors, the data process ing, normalization and co-registration methods. In order to further im prove mapping of rCBF with SPET it is imperative not only to improve t he spatial resolution but also to apply accurate correction techniques for scatter, attenuation and non-linear extraction.