Comparability of FDG PET studies in probable Alzheimer's disease

Results of studies with positron emission tomography (PET) of 18F-2-fluoro-2-deoxy-D-glucose (FDG) in patients with probable Alzheimer's disease (AD) were compared among three European centers with different PET scanners (in-plane resolution ranging between 6.75 mm and 9.2 mm). A ratio of glucose metabolism in the most typically affected regions over the least typically affected regions was calculated to quantitatively analyze the characteristic pattern of AD. Diagnostic accuracy of this composite ratio was high (95.8%) and was superior to that of most ratios derived from single regions. Correspondingly, there was a consistent, highly significant difference between patients (mean ratio 0.77 +/- 0.11) and normals (mean 0.99 +/- 0.04) without significant differences among laboratories. Possible small effects of rate constant variation and region size were analyzed by computer simulation. The results demonstrate that a common investigation protocol may yield FDG PET data in different laboratories that are closely comparable in spite of differences between scanners and imaging equipment.