Helical CT demonstration of dilated right inferior phrenic arteries as extrahepatic collateral arteries of hepatocellular carcinomas

Purpose: The purpose of this work was to demonstrate the: appearance of the right inferior phrenic artery (RIPA) on CT in patients with hepatocellular carcinoma (HCC). Method: We assessed the biphasic helical CT scans using 10 mm collimation i n 16 patients with arteriographically proven HCCs supplied by the RIPAs. Si ze of the right and left inferior phrenic arteries and origin of the RIPA w ere evaluated and correlated with arteriographic images. Results: Helical CT showed dilated RIPAs on the right diaphragmatic crus as foci of high attenuation on arterial-phase images in all patients. Diamete r of the RIPA (average 3.3 mm) was larger than that of the left inferior ph renic artery (average 1.5 mm). The origin of the RIPAs was correctly predic ted in 13 of 16 (celiac artery 6, abdominal aorta 5, right renal artery 2) patients. Conclusion: Asymmetric dilatation of the RIPA as an indicator of extrahepat ic collateral of HCC can be demonstrated on the right diaphragmatic crus wi th arteriographic images of biphasic helical CT.