In vivo MR measurements of regional arterial and venous blood volume fractions in intact rat brain.

In vivo measurement of cerebral arterial and venous volume fractions is important to the understanding of brain physiology and function. By using an intravascular perfluorocarbon and 19F NMR at 4.7 T, regional arterial and venous volume fractions from an intact rat brain were resolved based on the pseudodiffusion coefficients, which were (33 +/- 7) x 10(-3) and (0.45 +/- 0.13) x 10(-3) mm(2)/sec (mean +/- SD, n = 7) for the fast- and slow-moving component, respectively. By exploiting the linear dependence of the perfluorocarbon 19F 1/T1 on the dissolved paramagnetic oxygen concentration, combined inversion-recovery and diffusion measurements were made to correlate the short T1 (high-oxygenation) component with the fast-moving component and the long T1 (low-oxygenation) component with the slow-moving component. The arterial blood volume fraction was 29 +/- 7% of the total cerebral blood volume. Finally, experiments were performed in which different oxygen concentrations were inhaled to validate this technique.