Figure 18b.

Dementia with Lewy bodies. (a) Axial ¹²³I-ioflupane SPECT image in a patient with memory loss shows decreased left striatal uptake with a period appearance (red arrow), confirmatory of a parkinsonian neurodegenerative disease. Note the normal right striatal uptake with a comma appearance (green arrow), representing preserved putaminal uptake. (b) Sagittal ¹⁸F-FDG PET image shows subtle decreased uptake within the occipital region (arrow). (c) Parasagittal computer-generated map shows a statistically significant decrease in FDG uptake in the precuneus and occipital lobe (red arrows). Note that the posterior cingulate gyrus is spared (cingulate island sign), which is more readily apparent on the computer-generated map (green arrow) than on the ¹⁸F-FDG PET image. These findings corroborate the diagnosis of DLB.