Vascular-water-exchange imaging to detect blood-brain barrier breakdown in Alzheimer’s disease without contrast agent

Blood-brain-barrier (BBB) impairment is an important pathophysiological process in Alzheimer’s disease (AD). However, most neuroimaging methods assessing BBB function require contrast agent injection, limiting the methods’ application. Vascular-water-exchange imaging (VEXI), a version of filter-exchange imaging (FEXI), is a contrast-agent-free method assessing BBB permeability to water. We quantitatively measured BBB permeability using VEXI in normal subjects, mild cognitive impairment patients, and AD patients and found BBB breakdown occurred specifically in the hippocampus, worsening with disease progression. In addition, BBB permeability to water showed a significant correlation with cognitive impairment. Therefore, VEXI might be a potential contrast-agent-free neuroimaging method.