Early differential diagnosis between Alzheimer's disease and dementia with Lewy bodies: Comparison between 18F-FDG PET and 123I-IMP SPECT

• Neuroimaging approaches were compared in different forms of dementia.
• FDG PET and IMP SPECT would be useful for differential diagnosis between AD and DLB.
• FDG PET would be more useful than IMP SPECT for differential diagnosis in MCI.

Both 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and 123I-iodoamphetamine (IMP) single-photon emission computed tomography (SPECT) have been used for the differential diagnosis of Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Less information is available, however, regarding the differential diagnosis of mild cognitive impairment (MCI) due to AD and MCI due to DLB. We examined nine AD patients (AD group), nine DLB patients (DLB group), eight MCI due to AD patients (MCI-AD group), and nine MCI due to DLB patients (MCI-DLB group) with FDG PET and IMP SPECT using a well-characterized normal database and a stereotactic extraction estimation method. In the AD and DLB groups, receiver operating characteristic (ROC) analysis in the occipital regions showed significant accuracy of both FDG PET and IMP SPECT for the differential diagnosis. In the MCI-AD and MCI-DLB groups, ROC analysis showed significant accuracy of only FDG PET for the differential diagnosis. Both FDG PET and IMP SPECT would be useful for the differential diagnosis between AD and DLB. For the differential diagnosis of MCI-AD versus MCI-DLB, FDG PET would be more useful than IMP SPECT.