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47 to 68 years old (mean: 58.3; standard deviation: 5.7), and their MMSE score ranged from 4 to 26 (mean: 20.4; standard deviation: 6.1). The DLB patients were diagnosed in accordance with the 3rd International WS DLB, were 54 to 69 years old (mean: 61.6; standard deviation: 3.8), and their MMSE score ranged from 5 to 26 (mean: 16.7; stan-dard deviation 6.6).All subjects underwent head SPECT at our Radiology Department. For SPECT, TOSHIBA GCA 9300 A, and SIEMENS Symbia_E, and S were used. Additionally, a fan beam collimator was used. A tracer (99mTc-ECD) was administered to all participants at a supine position, with the eyes closed. The parameters of SPECT imaging were as follows: matrix size: 128×128; step angle: 4 degrees; view: 90; rotation time: 1min; and rotation: 16.Automatic analysis using eZIS (version 1.1.0) was performed to set a volume of interest (VOI). With eZIS, specific VOI analyses (SVA-A and SVA-B) were performed. The VOI of SVA-A is the area with significantly decreased blood flow (p < 0.001) in the 99mTc-ECD image of an incipient VOI１(blue): Areas where blood flow is decreased in DLB compared to healthy person.VOI２(red): Areas where blood flow is relatively maintained in DLB compared to AD.Figure 1　Examples of VOI1 and VOI2Alzheimer’s dementia patient with mildly impaired cognitive functions (amnestic MCI), which is comparatively analyzed against the 99mTc-ECD image of a healthy person. The image includes the posterior and anterior cingulate gyrus and a part of the vertex. As numerical indices, severity (degree of blood flow decrease in the VOI), extent (percentage of area with decreased blood flow in the VOI), and ratio (ratio of area with decreased blood flow in the VOI and that in the entire brain) are calculated. The VOI of SVA-B is the area with significantly decreased blood flow (p < 0.05) in the 99mTc-ECD image of a DLB patient compared with that of a healthy person. When this area VOI1 (mainly the posterior head) is subtracted from the VOI of the aforementioned SVA-A VOI, the VOI2 (mainly the posterior cingulate gyrus) is set (visu-alization in Figure 1). The sum of the Z scores in the area with decreased blood flow obtained from these two VOIs are used to calculate the CIScore (CIScore = sum of the Z scores in the decreased blood flow area obtained from the VOI2/sum of the Z scores in the decreased blood flow area obtained 507