Excessive Hepatic Arterial-portal Venous Shunting May Predict Failure of Microparticle Localization in Hepatocellular Carcinomas
A 58-year-old gentleman with a history of hepatitis C was detected to have an asymptomatic arterial enhancing right liver lobe mass on CT imaging, measuring approximately 6 × 8 cm in the longest cross-sectional diameter in liver segments 7/8, with evidence of branch portal vein thrombosis. His alpha fetoprotein levels were elevated as well. The results were in keeping with a hepatocellular carcinoma. He was subsequently referred for consideration of Y-90 SIRT using SIR-Spheres®. Biochemical evidence of underlying liver dysfunction was noted [albumin: 29 G/L, bilirubin: 26 umol/L, aspartate aminotransferase (AST): 164 U/L, alanine transaminase (ALT): 57 U/L, and prothrombin time (PT): 12.1 seconds], but values were still within acceptable limits for Y-90 SIRT.\nA hepatic angiogram was performed. A 5F Cobra catheter was advanced into the hepatic artery proper, and selective angiogram followed by an intra-arterial catheter CT angiogram was performed. The CT angiogram demonstrated good vascular blush in liver segments 7/8, corresponding to the tumor seen on prior CT imaging. However, subsequent portal venous enhancement was noted, indicating hepatic arterial-portal venous shunting [].\nFive millicuries of Tc-99m-MAA was subsequently administered slowly under manual hand control, and the patient underwent SPECT/CT imaging of the liver within one hour of administration of MAA.\nSPECT/CT imaging revealed minimal accumulation of MAA in the tumor in liver segment 7/8, with conversely more intense tracer localization in the surrounding liver parenchyma, resulting in an ‘inverse’-type localization of microspheres within the liver [].\nBased on the findings of the Tc99m-MAA SPECT/CT, the calculated TNR by partition dosimetry model was 0.18 with a liver lung shunting value of 19%. With a calculated dose limit to the normal liver parenchyma of 70 Gy, the radiation dose to the tumor was 36 Gy and to the lung was 15Gy. Based on assessment by partition modeling, the patient was deemed not a suitable candidate for Y-90 SIRT.