Assessment of 99Tcm-HMPAO tumour scintigraphy using VX-2 tumours implanted in a lower limb muscle of rabbits.

Tumour scintigraphy using 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HMPAO) was investigated in VX-2 tumours implanted in the muscles of the lower legs of rabbits to assess the feasibility of using this agent clinically for this procedure. On the time-activity curves for 99Tcm-HMPAO in the tumour, an initial peak and a subsequent decrease of radioactivity immediately after the initial peak were observed, while there was a slow, gradual decrease of activity over the next hour. The tumour/normal muscle ratio of HMPAO activity during this period was high and constant, and was independent of time. Comparison of the static images of 99Tcm-HMPAO with angiography and histological findings suggests that the tumour image of 99Tcm-HMPAO reflects tumour blood perfusion. These findings indicate that the distribution of 99Tcm-HMPAO on static images can provide a qualitative assessment of the perfusion of the tumour, despite the limitations of this tracer for quantifying tumour blood flow due to its early efflux from the tumour.