[The assessment of 99mTc-HMPAO tumor scintigraphy using VX-2 tumors in rabbits]

Tumor scintigraphy using 99mTc-hexamethyl-propyleneamine oxime (99mTc-HMPAO) was performed in VX-2 tumors implanted in the muscles of the lower limbs of rabbits to evaluate the possibility that this agent could be used to estimate the blood perfusion of the tumor. The distribution of 99mTc-HMPAO in the tumor immediately after the intravenous injection of this radiopharmaceutical exhibited almost the same distribution on the static image 1 hour after administration. Tumor time-activity curve for 99mTc-HMPAO revealed initial peak after the injection followed by fading of 99mTc-HMPAO activity and subsequent gradual decrease in activity over the next 1 hour. The ratio of 99mTc-HMPAO activity in the tumor to that in normal muscle tissue during this next 1 hour was high and independent of time. These findings indicate that static 99mTc-HMPAO scintigraphy can provide qualitative but not quantitative data useful in the estimation of tumor blood perfusion. Moreover, comparison of distribution of 99mTc-HMPAO on the static images and angiographic, histological findings also suggest that static 99mTc-HMPAO images accurately reflect tumor blood perfusion.