When Perfusion Meets Diffusion in vivo Measurement of Water Extraction and Permeability in Human Brain
Fernandez-Seara M, Wang J, Detre J, St Lawrence K
University of Pennsylvania
A hybrid MRI technique was introduced by marrying a continuous arterial spin labeling (ASL) method with a twice-refocused spin-echo diffusion sequence. Diffusion weighted ASL signals were acquired with systematically varied b values up to 300 s/mm2, and were modeled based on a biexponential decay model. Water extraction fraction was estimated by differentiating the amount of labeled water in the vascular and tissue compartments, based on their diffusion characteristics. According to the single-pass approximation model, we further estimated the water permeability of human brain based on the derived water extraction fractions.