Quantitation of rat cerebral blood flow using Tc-HMPAO.

INTRODUCTION

Technetium-99m-hexamethylpropyleneamine oxime (Tc-HMPAO) is potentially useful for the assessment of cerebral blood flow (CBF) in small animals. In this paper, a procedure for quantitation of rat CBF using Tc-HMPAO was determined.

METHODS

Biodistribution of Tc-radioactivity in normal rats was determined after intravenous administration of Tc-HMPAO. Acetazolamide treated rats were intravenously administered with the mixture of Tc-HMPAO and N-isopropyl-[I]iodoamphetamine ([I]IMP), and arterial blood was then collected for 5min. After blood sampling, the brain radioactivity concentration was measured with the auto-well γ counter.

RESULTS

The brain radioactivity concentration after intravenous administration of Tc-HMPAO was steady from 14s to 60min post-injection. A double tracer experiment using Tc-HMPAO and [I]IMP showed that 19s was the average of the optimal integration interval of arterial blood Tc-radioactivity concentration to obtain CBF values measured by Tc-HMPAO identical to those determined by [I]IMP. The CBF value determined by Tc-HMPAO, calculated by dividing the brain radioactivity concentration at 5min post-injection by the integrated arterial blood radioactivity concentration until 19s post-injection, was well correlated with CBF as determined by [I]IMP.

CONCLUSION

These results suggest that the CBF quantitation procedure described in this paper could be useful for rat CBF assessment.