High‐sensitivity single‐shot perfusion‐weighted fMRI †

A method is presented for measurement of perfusion changes during brain activation using a single‐shot pulsed spin labeling technique. By employing a double‐inversion labeling strategy, stationary tissue (background) signal was suppressed while minimally affecting perfusion sensitivity. This allowed omission of the otherwise required reference scan, resulting in twofold‐improved temporal resolution. The method was applied to visual and motor cortex activation studies in humans, and compared to standard FAIR‐type perfusion labeling techniques. Experiments performed at 1.5T and 3.0T indicate a close to 90% suppression of background signal, at a cost of an 11% and 9%, respectively, reduction in perfusion signal. Combined with the twofold increase in signal averaging, and a reduction in background signal fluctuations, this resulted in a 64% (1.5T, N = 3) and a 128% (3T, N = 4) overall improvement in sensitivity for the detection of activation‐related perfusion changes. Magn Reson Med 46:88–94, 2001. Published 2001 Wiley‐Liss, Inc.