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 arteriovenous shunts in malignant liver tumors by injection of ^99mTc macroaggregates 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 ^99mTc MAA was injected arterially during angiography. 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 patients had shunts ranging from 18% to 37%. In patients with colorectal 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 correlation to the tumor volume or to the pattern of vascularity on angiography. Conclusion: Diagnostic angioscintigraphy is a useful tool for pretherapeutic evaluation of the capacity of an individual tumor to retain particles and to measure extratumoral shunting; these are essential for therapy planning, as they can help to increase the safety and effectiveness of embolization.