Radiology
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Purpose To compare PET/MR hypoperfusion and hypometabolism in patients with Alzheimer disease (AD) and mild cognitive impairment (MCI) compared with healthy control (HC) participants. Materials and Methods Maps of cerebral blood flow (CBF; pulsed arterial spin-labeling [ASL] MRI), glucose metabolism (fluorine 18 [18F] fluorodeoxyglucose [FDG] PET), and gray matter (GM) volume (structural T1-weighted MRI) were calculated from integrated PET/MR data in 45 patients with AD (mean age, 69 years ± 9 [standard deviation]; age range, 51-89 years), 20 patients with MCI (mean age, 64 years ± 10; age range, 45-82 years), and 11 HC participants (mean age, 65 years ± 8; age range, 54-80 years) between 2011 and 2014. After preprocessing, voxel-wise analyses of variance, volume of interest, and independent component analyses were performed for comparisons of CBF and glucose metabolism. ⋯ Volume-of-interest analysis in global GM in patients with AD compared with HC participants showed lower CBF (42 mL/100 g per minute ± 8 vs 49 mL/100 g per minute ± 7, respectively; P = .035) and lower FDG uptake (0.8 ± 0.1 vs 1 ± 0.1, respectively; P < .001). Conclusion In patients with AD, pulsed ASL MRI revealed regional and quantitative abnormalities and components similar to 18F-FDG PET with a reduced extent. In patients with MCI, 18F-FDG PET exclusively demonstrated quantitative hypometabolism and a component in the precuneus, indicating higher sensitivity to detect preclinical AD compared with the currently used pulsed ASL MRI sequence.