Improved reliability for mapping water exchange across blood-brain barrier by diffusion prepared three-dimensional pseudo-continuous arterial spin labeling

A 3D diffusion-prepared gradient and spin echo (GRASE) pseudo-continuous ASL (pCASL) sequence was proposed to improve the reliability for mapping water exchange across the BBB non-invasively. The motion sensitive non-CPMG component signal was eliminated by gradients to spread the diffusion weighted signal across 4π before GRASE readout. Based on test-retest scans (~2 weeks apart) in aged subjects (67±8yrs), excellent reproducibility (ICC=0.87) was achieved for water exchange rate (Kw) measured by the proposed 3D sequence. Whole brain Kw was averaged to be 107.7±19.0 min^-1 and 113.0±17.8 min^-1 for the proposed 3D and 2D DW-pCASL method, respectively, well matching the literature results.