18F-FDG-PET provides a functional neurodegenerative biomarker in the Alzheimer’s continuum, but it is costly and involves exposure to ionizing radiation. Arterial Spin Labeled (ASL) perfusion MRI can be acquired during routine MRI session to measure cerebral blood flow (CBF), which is tightly coupled with cerebral metabolism. We demonstrated that the ASL hypoperfusion pattern was similar to that of FDG-PET-hypometabolism in patients with mild cognitive impairment. Further, ASL-CBF provided complementary information to hippocampal atrophy measured with structural MRI. Multimodal MRI may provide a cost-effective and totally noninvasive substitute for 18F-FDG-PET in clinical and research setting for detecting Alzheimer’s neurodegeneration.