Fig. 2

Brain MRI and cerebral blood flow findings at 75 and 77 years of age. At age 75, magnetic resonance imaging (MRI) showed cerebral atrophy of the temporal lobe, parietal lobe, and frontal lobe with dominance in the left cerebral hemisphere, and bilateral ventricular dilatation was also observed (a). In this image, the region and degree of decreased blood flow was objectively evaluated by displaying how many standard deviations the pixel value of the analyzed case deviates from the normal mean value using Z-score [Z-score = (normal mean value − case pixel value)/normal standard deviation]. The Z-score is indicated by 0 (blue) to 5 (red); the higher the value, the stronger the decrease in blood flow. Single-photon emission computed tomography (SPECT) with N-isopropyl-p-(iodine-123)-iodoamphetamine (IMP) revealed a reduction of cerebral blood flow in the left hemisphere with slight predominance in the frontal, temporal, and parietal lobes and posterior cingulate gyrus to cuneus (b). At age 77, the brain atrophy extended to the temporal-parietal lobe of the right hemisphere, with bilateral frontal lobe atrophy (c). Consistently, blood flow reduction was spread over a wide area in the right hemisphere, and a reduction in blood flow is observed in the bilateral frontal lobe, temporal lobe, and parietal lobe. Arrows demonstrate the areas of the region where hypoperfusion has expanded (d)