The Value of Multimodal Imaging with 123I-FP-CIT SPECT in Differential Diagnosis of Dementia with Lewy Bodies and Alzheimer’s Disease Dementia

Abstract Reduced nigrostriatal uptake on 123I-FP-CIT SPECT reflects dopamine dysfunction, while other imaging markers could be complementary when used together. We assessed how well 123I-FP-CIT SPECT differentiates Dementia with Lewy Bodies (DLB) from Alzheimer’s Disease Dementia (ADem) and whether multimodal imaging provides additional value. 123I-FP-CIT SPECT, MRI, FDG-PET, and PiB-PET were assessed in 35 DLB and 14 ADem participants (autopsy confirmation in 9 DLB and 4 ADem). Nigrostriatal dopamine transporter uptake was evaluated with 123I-FP-CIT SPECT using DaTQUANT software. Hippocampal volume was calculated with MRI, cingulate island sign (CIS) ratio with FDG-PET, and global cortical PiB retention with PiB-PET. The DaTQUANT z-scores of putamen showed the highest c-statistic of 0.916 in differentiating DLB from ADem among the analyzed imaging biomarkers. Adding another imaging modality to 123I-FP-CIT SPECT had c-statistics ranging from 0.968 to 0.975, and 123I-FP-CIT SPECT in combination with two other imaging modalities presented c-statistics ranging from 0.987 to 0.996. These findings suggest that multimodal imaging with 123I-FP-CIT SPECT aids in differentiating DLB and ADem, and in detecting comorbid Lewy-related and AD pathology in DLB and ADem patients.