In vivo measurement of CBF using ¹⁷O NMR signal of metabolically produced H₂¹⁷O as a perfusion tracer.

The cerebral metabolic rate of oxygen of small animals can be reliably imaged using the in vivo (17) O magnetic resonance approach at high field. However, a separate measurement is required for imaging the cerebral blood flow in the same animal. In this study, we demonstrate that the (17) O NMR signal of metabolically produced H2 (17) O in the rat brain following an (17) O2 inhalation can serve as a perfusion tracer and its decay rate can be used to determine the absolute values of cerebral blood flow across a wide range of animal conditions. This finding suggests that the in vivo (17) O magnetic resonance approach is capable of imaging both cerebral metabolic rate of oxygen and cerebral blood flow simultaneously and noninvasively; and it provides new utilities for studying the cerebral oxygen metabolism and perfusion commonly associated with brain function and diseases.