Simultaneous measurement of cerebral blood flow and transit time with turbo dynamic arterial spin labeling (Turbo-DASL): Application to functional studies

A turbo dynamic arterial spin labeling method (Turbo-DASL) was developed to simultaneously measure cerebral blood flow (CBF) and blood transit time with high temporal resolution. With Turbo-DASL, images were repeatedly acquired with a spiral readout after small-angle excitations during pseudocontinuous arterial spin labeling and control periods. Turbo-DASL experiments at 9.4 T without and with diffusion gradients were performed on rats anesthetized with isoflurane or a-chloralose. We determined blood transit times from carotid arteries to cortical arterial vessels (TTa) from data obtained without diffusion gradients and to capillaries (TTc) from data obtained with diffusion gradients. Cerebral arterial blood volume (CBVa) was also calculated. At the baseline condition, both CBF and CBVa in the somatosensory cortical area were 4050% less in rats with a-chloralose than in rats with isoflurane, while TTa and TTc were similar for both anesthetics. Absolute CBF and CBVa were positively correlated, while CBF and TTc were slightly negatively correlated. During forepaw stimulation, CBF increase was 15 +/- 3% (n = 7) vs. 60 +/- 7% (n = 5), and CBVa increase was 19 +/- 9% vs. 46 +/- 17% under isoflurane vs. a-chloralose anesthesia, respectively; CBF vs. CBVa changes were highly correlated. However, TTa and TTc were not significantly changed during stimulation. Our results support that arterial CBV increase plays a major role in functional CBF changes. Magn Reson Med, 2012. (c) 2011 Wiley Periodicals, Inc.