In vivo Hadamard encoded continuous arterial spin labeling (H-CASL).

Continuous arterial spin labeling (CASL) measurements over a range of post-labeling delay (PLD) times can be interpreted to estimate cerebral blood flow (CBF) and arterial transit time (deltaa) with good spatial and temporal resolution. In this work, we present an in vivo demonstration of Hadamard-encoded continuous arterial spin labeling (H-CASL); an efficient method of imaging the inflow of short boli of labeled blood water in the brain at multiple PLD times. We present evidence that H-CASL is viable for in vivo application in the rat brain and can improve the precision of deltaa estimation in 2/3 of the imaging time required for standard multi-PLD CASL. Based on these findings, we propose that H-CASL may have application as an efficient prescan for optimization of ASL imaging parameters to improve the precision of CBF estimation.