DIAGNOSTIC ANGIOSCINTIGRAPHIC EVALUATION OF MALIGNANT HEPATIC-TUMORS BEFORE CATHETER EMBOLIZATION - DETERMINATION OF SHUNT, FLOW DISTRIBUTION, AND REFLUX

Purpose: The aim of this study was to evaluate quantitatively arteriov enous shunts in malignant liver tumors by injection of Tc-99m macroagg regates of albumin (MAA) into the tumor-feeding artery after selective catheterization. Methods: In 40 patients with malignant liver tumors (33 hepatocellular carcinomas and 7 metastases of colorectal cancer), a mean dose of 200 MBq Tc-99m MAA was injected arterially during angio graphy. The embolized area and the lungs were then visualized using a gamma camera. A dedicated computer program calculated pulmonary shunt rates. Results: The majority of patients (n = 30) with hepatocellular carcinoma showed small shunts varying from 0 to 15%; only 3 of these p atients had shunts ranging from 18% to 37%. In patients with colorecta l carcinoma metastases (n = 7) the shunt varied from 0 to 3% (2 +/- 1% ), probably due to a physiological shunt in normal liver tissue in the embolized area. Importantly, the degree of shunt found bore no correl ation to the tumor volume or to the pattern of vascularity on angiogra phy. Conclusion: Diagnostic angioscintigraphy is a useful tool for pre therapeutic evaluation of the capacity of an individual tumor to retai n particles and to measure extratumoral shunting; these are essential for therapy planning, as they can help to increase the safety and effe ctiveness of embolization.