Development of quantitative evaluation method of cerebral circulation using RI tracer in animal experiments

Abstract

Cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO₂) and cerebral oxygen extraction fraction (OEF) are some of the most fundamental parameters to characterize the pathophysiologic status of cerebral tissue, especially. after the onset of cerebral infarction. Positron emission tomographic imaging (PET) using [¹⁵O]O₂ gas is a useful tool for measuring these parameters, but there is no time to perform PET studies in clinical practice. Therefore, animal examination is effective to explore cerebral circulatory metabolic condition in the acute phase. We developed an injectable [¹⁵O]O₂ imaging agent for the purpose of measuring OEF and CMRO₂ in an animal model using a small animal PET system. Furthermore, we developed a quantitative CBF evaluation method without arterial blood sampling using [^99mTc]HMPAO with a small animal SPECT system.