Measurement of local cerebral blood flow by magnetic resonance imaging:: In vivo autoradiographic strategy using 17O-labeled water

Local cerebral blood flow (LCBF) was measured in cats by magnetic resonance imaging (MRI), using O-17-labeled water ((H2O)-O-17) as a tracer. Cat brain images were obtained using a 256 x 240 matrix fast spin-echo sequence with a total acquisition time of 124 seconds per image. Intravenous injection of H, O and sampling of arterial blood were simultaneously performed during the MRI scan, Injection of (H2O)-O-17 over 40 seconds caused a transient decrease in brain signal intensity, from which the changes in (H2O)-O-17 concentration of brain tissue were calculated. The concentration of (H2O)-O-17 in arterial blood was measured directly by O-17 nuclear magnetic resonance (NMR) spectroscopy, and used as an input function for the calculation of LCBF, LCBF was successfully determined using an in vivo autoradiographic strategy in a total of three cats, In one, LCBF measurements were also performed under hypercapnic conditions, and LCBF maps of the cat brain during normocapnia and hypercapnia were constructed. These LCBF maps reflected well the changes in LCBF induced by hypercapnia, which indicated the validity of the used method. (C) 1998 Elsevier Science Inc.