Hepatic arterial perfusion scintigraphy

Learning Objectives 1. To understand the significance of hepatic arterial perfusion scintigraphy compared to contrast angiography for confirmation of proper arterial catheter placement prior to selective chemo or radiation therapy. 2. To understand the differential perfusion of tumor and non-tumor hepatic tissue for selective targeting of the tumor. 3. To understand the normal and abnormal scintigraphic patterns of the hepatic arterial pump study.

Summary: Hepatic arterial perfusion scintigraphy (HAPS) and contrast angiography are used to confirm the proper placement of hepatic artery infusion catheter prior to delivery of arterial chemotherapy or Y⁹⁰ microspheres for hepatic malignancy. Unlike contrast angiography, HAPS selectively images the capillary distribution at a physiological flow rate. Tc-99m MAA is trapped in the hepatic arterial capillary bed distributing into the malignant lesions as compared to the normal hepatic tissue perfused predominantly by portal vein. This results in scintigraphic hot spots indicating adequate distribution in regions of tumor. It is important to know the normal distribution in order to recognize the incorrect positioning of the arterial catheter resulting in extra-hepatic perfusion to the viscera (usually stomach or pancreas, spleen and bowel) or shunting to the lungs. The absence of extra hepatic perfusion and minimal lung shunting with adequate perfusion to the tumor on HAPS indicates appropriate selective delivery of the treatment and minimal systemic toxicity. Examples of normal and abnormal hepatic arterial perfusion scintigraphy and correlative radiological images will be included for illustration.