BRAIN BLOOD-FLOW MEASURED WITH INTRAVENOUS (H2O)-O-15 .2. IMPLEMENTATION AND VALIDATION

Abstract

The well-known tissue autoradiographic technique for the measurement of regional cerebral blood flow (CBF), originally proposed by Kety and his colleagues, was adapted for the measurement of CBF in human subjects using positron emission tomography (PET) and i.v. administered H215O. The steps necessary for the implementation of this PET/autoradiographic technique are described. To establish the accuracy of the method, CRF was measured with i.v. administered H215O and PET in anesthetized adult baboons and the results were compared with blood flow measured by a standard tracer technique that uses residue detection of a bolus of H215O injected into the internal carotid artery. The correlation between CBF measured with PET and the true CBF for the same cerebral hemisphere was excellent. Over a blood-flow range of 10-63 ml/(min.cntdot.100 g ), CBF (PET) = 0.90 CBF(true) + 0.40 (n = 23, 4 = 0.96, P < 0.001). When blood flow exceeds 65 ml/(min .cntdot. 100 g) CBF was progressively underestimated due to the known limitation of brain permeability to water.