Blood-Brain Barrier (BBB) assessment by MRI The imaging modality used for BBB assessment will be MRI scanner (Philips 3T or General Electric 1.5T). The examination format will include 24 cm FOV, 35 contiguous interleaved slices, 3.5-4 mm thick and co-localized across series. Trace-weighted DWI images will be obtained at b=1000 from a 13-15 direction DTI sequence with an in-plane resolution of 2.5×2.5mm and TR/TE=10s/58ms at 3T or TR/TE=10s/72ms at 1.5T. T2-FLAIR images will be obtained with an in-plane resolution of 0.94×0.94 mm, TR/TE=9000/120 ms and TI=2600 ms at 3T or TR/TE=9000/140 ms and TI=2200 ms at 1.5T. (25)