Aim: There are several approaches for correcting the effects of photon scatter or absorption by body tissues on positron emission tomography (PET). We examined the influence of cold, hot and segmented transmission as well as of a mathematical procedure on attenuation correction using regional cerebral glucose metabolism (rMRGlu).
Methods: 6 patients with different cerebral diseases were examined under resting conditions using an ECAT Exact 922/47. The attenuation-corrected data (corrected by means of cold, hot and segmented transmission as well as a mathematical procedure) were then quantified absolutely for assessment of regional glucose metabolism in 16 regions of interest (ROIs).
Results: Using absolutely quantified glucose metabolism in 16 ROIs, no significant differences were found between cold transmission and the mathematical procedure except for three regions (left and right temporal occipital and right parietal occipital). Unlike the mathematical procedure, both hot and segmented transmission showed a significantly lower value for regional glucose utilization in all 16 ROIs than did cold transmission. The left and the right hemisphere both showed metabolic values (rMRGlu) in the same decreasing order: cold transmission, the mathematical procedure, hot or segmented transmission. There was no significant difference between global cerebral glucose metabolism values for cold transmission and the mathematical procedure (p = 0.25) while those for hot (p = 0.03) and segmented transmission (p = 0.03) did show a significant difference.
Conclusions: Except for 3 regions (temporo-occipital left, temporo-occipital right and parieto-occipital right) attenuation correction procedures used for brain PET studies on patients show no significant quantitative differences between cold transmission and the mathematical procedure. rMRGlu of images corrected for attenuation using hot and segmented transmission is significantly lower than of attenuation corrected images where cold transmission was employed. For clinical routine examinations, the mathematical procedure seems the best alternative to cold transmission for a faster brain PET acquisition.