Indirect 17O-magnetic resonance imaging of cerebral blood flow in the rat

Proton T-1p dispersion MRI is demonstrated for indirect, in vivo detection of O-17 in the brain. This technique, which may be readily implemented on any clinical MRI scanner, is applied towards high-resolution, quantitative mapping of cerebral blood flow (CBF) in the rat by monitoring the clearance of O-17-enriched water. Strategies are derived and employed for 1) quantitation of absolute H-2 O-17 tracer concentration from a ratio of high- and low-frequency spin-locked T-1p images, and 2) mapping CBF without having to transform the T-1p signal to H-2 O-17 tracer concentration. Absolute regional blood flow was mapped in a single 3-mm brain slice at an in-plane resolution of 0.4 x 0.8 mm within a 5-min tracer washout time; these data are consistent with the less localized CBF measurements reported in the literature. T-1p- weighted imaging yields excellent signal-to-noise ratios, spatiotemporal resolution, and anatomical contrast for mapping CBF. (C) 2003 Wiley-Liss, Inc.