Quantitative hepatic arterial perfusion scintigraphy and starch microspheres in cancer chemotherapy.

Hepatic arterial infusion chemotherapy results in a higher concentration of drug delivered to the tumor with less systemic exposure than is possible with intravenous therapy. However, extrahepatic blood flow and/or shunting to the lung can impose a limitation. This study describes a quantitative method for calculating the extrahepatic component and monitoring its changes due to a new adjunctive therapy, degradable starch microspheres (DSM). DSM temporarily occlude the hepatic arterial circulation, thereby increasing the uptake of therapeutic drugs. Twenty patients with metastatic liver cancer underwent hepatic arterial perfusion scintigraphy (HAPS) using Tc-99m MAA to determine blood-flow distribution and to quantitate extrahepatic uptake. The percent shunt index (PSI) was determined at baseline and after each incremental dose of DSM. The baseline PSI ranged from 6-26% (mean 12.3 +/- 5.8 s.d.) and changed progressively after each injection of DSM/Tc-MAA suspension. The patterns of change in shunting are described. Quantitative HAPS provides a means of measuring the extrahepatic component, warns of potential side effects, and helps guide chemotherapeutic decisions.