Pulmonary uptake of technetium 99m macroaggregated albumin: a predictor of gastrointestinal toxicity during hepatic artery perfusion.
Hepatic artery infusion of 5-fluoro-2-deoxyuridine (5-FUdR) provides high hepatic drug levels but little systemic toxicity, since, by this route of administration, the drug is detoxified by the hepatocytes. Slow infusion of technetium 99m- (99mTc) labeled macroaggregated albumin (MAA) through the hepatic artery is an aid in catheter placement, in predicting response of liver metastases to therapy, and in identifying extra-hepatic flow in the gastroduodenal or splenic arteries as an indicator of systemic toxicity. Marked pulmonary uptake of this tracer after slow radionuclide hepatic angiography was noted in four patients who showed major gastrointestinal (GI) toxicity. A retrospective examination of pulmonary accumulation of 99mTcMAA as a predictor of GI toxicity is the subject of this paper. Two groups of patients were evaluated. The first group consisted of 14 consecutive patients in whom continuous infusion of drug was administered by an external pump by way of a percutaneous catheter. Patients received baseline and follow-up (seven to 27 days) slow-infusion tracer studies (2 to 4 mCi 99mTcMAA at 10 to 21 mL/h). The second group included 14 consecutive patients who were receiving intraarterial chemotherapy by a totally implantable pump system. All received baseline slow-infusion studies (2 to 4 mCi 99mTcMAA at approximately 0.5 to 1.0 mL/min). The percentage of the injected dose in the lung was determined. Patients with greater than 20% of tracer in the lung after radionuclide hepatic angiography had significantly greater severe GI toxicity than patients with baseline values of less than 20%. Our findings support the existence of hepatic arteriovenous (A-V) communications in some patients and suggest that they are present pretherapy. Presence of these A-V communications, which can result in a vascular bypass of normal hepatic parenchyma and the subsequent decrease in hepatic detoxification of chemotherapeutic agents, is the likely cause of GI toxicity. Pulmonary uptake of tracer injected in the hepatic artery may be useful in quantifying the degree of shunting and facilitate the monitoring of potential systemic toxicity.