The utility flourodeoxyglucose PET (FDG-PET) imaging in Alzheimer’s Disease (AD) diagnosis is well established. Recently, measurement of cerebral blood flow using arterial spin labeling MRI (ASL-MRI) has shown diagnostic potential in AD, though it has never been directly compared to FDG-PET.
We employed a novel imaging protocol to obtain FDG-PET and ASL-MRI images concurrently in 17 AD patients and 19 age-matched controls. Paired FDG-PET and ASL-MRI images from 19 controls and 15 AD patients were included for qualitative analysis, while paired images 18 controls and 13 AD patients were suitable for quantitative analyses.
The combined imaging protocol was well tolerated. Both modalities revealed very similar regional abnormalities in AD, as well as comparable sensitivity and specificity for the detection of AD following visual review by two expert readers. Interobserver agreement was better for FDG-PET (kappa 0.75, SE 0.12) than ASL-MRI (kappa 0.51, SE 0.15), intermodality agreement was moderate to strong (kappa 0.45-0.61), and readers were more confident of FDG-PET reads. Simple quantitative analysis of global cerebral FDG uptake (FDG-PET) or whole brain cerebral blood flow (ASL-MRI) showed excellent diagnostic accuracy for both modalities, with area under ROC curves of 0.90 for FDG-PET (95% CI 0.79-0.99) and 0.91 for ASL-MRI (95% CI 0.80-1.00).
Our results demonstrate that FDG-PET and ASL-MRI identify similar regional abnormalities and have comparable diagnostic accuracy in a small population of AD patients, and support the further study of ASL-MRI in dementia diagnosis.