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Abstract #1767

Simultaneous Measurements of Arterial Transit Times and Water Exchange Rates by Diffusion-Weighted ASL

Keith S. St. Lawrence1,2, Jodi Miller1, Jiongjiong Wang3

1Imaging, Lawson Health Research Institute, London, ON, Canada; 2Medical Biophysics, University of Western Ontario, London, ON, Canada; 3Radiology, University of Pennsylvania, Philadelphia, PA, United States

The arterial transit time (τa) and the exchange rate of water (kw) across the blood-brain barrier were determined using diffusion-weighted arterial spin labelling (ASL) with multiple post-labelling delay times. τa was determined using bipolar gradients to suppress the arterial signal (i.e., the FEAST method) and kw was determined using bipolar gradients strong enough to suppress all vascular signals and a kinetic model to characterize water exchange across the BBB. Averaged over four volunteers, kw was 119 min-1 in grey matter and τa was 1.26 s. From repeat measurements, the intra-subject coefficient of variation of kw was 12%.