The Cingulate Island Sign on FDG-PET vs. IMP-SPECT to Assess Mild Cognitive Impairment in Alzheimer's Disease vs. Dementia with Lewy Bodies
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Updated: Jun 27, 2026

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG
Published on: December 28, 2014
Yuhei Chiba1,2,3, Hiroshige Fujishiro1,4, Eizo Iseki1,5
1PET/CT Dementia Research Center, Juntendo Tokyo Koto Geriatric Medical Center, Juntendo University School of Medicine, 3-3-20 Shinsuna, Koto-Ku, Tokyo, 136-0075, Japan.
Background And Purpose:
The cingulate island sign (CIS) on 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET); ie, the relative preservation of mid-posterior cingulate cortex metabolism, is a supportive biomarker in the diagnostic criteria for dementia with Lewy bodies (DLB). However, limited information is currently available on the diagnostic value of the CIS on FDG-PET or 123 I-iodoamphetamine single-photon emission computed tomography (IMP-SPECT) for differentiating between mild cognitive impairment (MCI) due to Alzheimer's disease (AD) (MCI-AD) and MCI due to DLB (MCI-DLB).
Methods:
We examined the CIS ratio in 9 AD patients, 9 DLB patients, 8 patients with MCI-AD, and 9 patients with MCI-DLB using FDG-PET and IMP-SPECT. The CIS ratio was calculated using NEUROSTAT software.
Results:
In the dementia groups, a receiver operating characteristic analysis of the CIS ratio showed significant accuracy for differentiating between AD and DLB on FDG-PET and IMP-SPECT. In the MCI groups, only the FDG-PET derived CIS ratio displayed significant accuracy for differentiating between AD and DLB.
Conclusions:
The FDG-PET and IMP-SPECT derived CIS ratios are both useful for differentiating between AD and DLB. The FDG-PET derived CIS ratio is more valuable than the IMP-SPECT derived CIS ratio for differential diagnosis in patients with MCI. A larger study is needed to confirm these results.
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