Objective To estimate the anatomic variation of the right inferior phrenic artery(RIPA)with multi-detector tomography(MDCT)scans.Methods 45 patients with hepatocellular carcinoma(HCC)and 46 healthy subjects were examined by contrast-enhanced CT scan(CTA)at 16-section CT scanner.Then the images were reconstructed with MPR,VR and MIP.Results RIPA were detected by CTA in all cases(sensitivity was 100%).The origin of RIPAs directly from the aorta in 42%,celiac trunk in 37%,right renal artery in 15%,left gastric artery in 3% and proper hepatic artery in 2%.For the reconstructive images quality,MPR and MIP were better than VR,but in showing the origin of RIPAs,MPR and VR were better than MIP.In compared with normal group,the diameters of RIPAs in tumor group were larger.Conclusion MDCT estimates well for the anatomy of RIPAs,which is significant for planning and embolization of extrahepatic RIPA supply in HCC.