To review the current evidence supporting arterial spin-labeling MRI (ASL-MRI) as a cost-effective, noninvasive biomarker for monitoring neurodegenerative disease progression and treatment response, emphasizing its role as an alternative to FDG-PET and amyloid imaging.

Positron emission tomography (PET) remains the reference standard for assessing cerebral metabolism and amyloid burden in Alzheimer’s disease (AD) and related disorders. However, its high cost, limited accessibility, and dependence on radiotracers restrict its use for routine monitoring. ASL-MRI quantifies cerebral blood flow (CBF) without contrast or radiation and reflects metabolic activity through neurovascular coupling. Emerging evidence suggests ASL-MRI can detect regional hypoperfusion patterns analogous to PET and track longitudinal perfusion recovery in patients treated with anti-amyloid monoclonal antibodies.

A narrative review was conducted summarizing findings from key studies evaluating ASL-MRI as a biomarker in neurodegenerative diseases, including Alzheimer’s disease, frontotemporal dementia, and Lewy body dementia. Particular emphasis was placed on comparative studies with FDG-PET and longitudinal imaging in patients receiving lecanemab or donanemab therapy.

Across studies, ASL-MRI demonstrates high concordance with FDG-PET for temporoparietal and posterior cingulate hypoperfusion in AD, with specificity exceeding 80%. Longitudinal analyses reveal measurable increases in CBF following anti-amyloid therapy, paralleling cognitive stabilization or improvement. In other neurodegenerative conditions, ASL-MRI captures disease-specific perfusion signatures reflecting neuronal loss and network dysfunction. Its lower cost, absence of tracers, and repeatability make it suitable for serial imaging and real-world clinical follow-up.