OBJECTIVE: Recurrent hepatocellular carcinoma (HCC) often occurs with extrahepatic arterial supply (parasitic supply), essentially due to liver intraarterial chemoembolization, which could potentially hamper retreatment. The right inferior phrenic artery (RIPA) is the most frequent extrahepatic feeding artery. We investigated computed tomography (CT) findings of parasitic supply by the RIPA, and discuss the utility of multiphasic CT for prediction of parasitic supply from RIPA. METHOD: Medical records, CT scans, and angiograms in 20 patients with HCC fed by RIPA were reviewed. Forty-two patients with HCC but without parasitic supply were enrolled as the control group. After injection of contrast medium (300 mg I/mL) at a rate of 3 mL/s (total amount, 100 mL), CT images were obtained at 30 seconds, 60 seconds, and 150 seconds with scanning parameters of 7-mm collimation, 1:1 pitch, and 3.5-mm reconstruction. Two radiologists evaluated the previous treatment, patency of the hepatic arteries, location of tumors, and detectability and diameter of the RIPA. RESULTS: CT demonstrated at least one portion of RIPA in all patients in both groups. The distal portions of RIPA were detected on CT more frequently in the parasitic group (75%) than in the control group (7.1%). The mean diameter of the RIPA in the parasitic group was 2.3 mm (range; 1.6-3.8), and was larger than that of the control group (mean; 1.3 mm and range; 0-4.1mm) with statistical significance (P < 0.01). CONCLUSIONS: Multiphasic CT could demonstrate the presence of parasitic supply to HCCs from RIPA. Visualization of RIPA at the distal portion on CT would be a clue of parasitic supply from RIPA.
OBJECTIVE: Recurrent hepatocellular carcinoma (HCC) often occurs with extrahepatic arterial supply (parasitic supply), essentially due to liver intraarterial chemoembolization, which could potentially hamper retreatment. The right inferior phrenic artery (RIPA) is the most frequent extrahepatic feeding artery. We investigated computed tomography (CT) findings of parasitic supply by the RIPA, and discuss the utility of multiphasic CT for prediction of parasitic supply from RIPA. METHOD: Medical records, CT scans, and angiograms in 20 patients with HCC fed by RIPA were reviewed. Forty-two patients with HCC but without parasitic supply were enrolled as the control group. After injection of contrast medium (300 mg I/mL) at a rate of 3 mL/s (total amount, 100 mL), CT images were obtained at 30 seconds, 60 seconds, and 150 seconds with scanning parameters of 7-mm collimation, 1:1 pitch, and 3.5-mm reconstruction. Two radiologists evaluated the previous treatment, patency of the hepatic arteries, location of tumors, and detectability and diameter of the RIPA. RESULTS: CT demonstrated at least one portion of RIPA in all patients in both groups. The distal portions of RIPA were detected on CT more frequently in the parasitic group (75%) than in the control group (7.1%). The mean diameter of the RIPA in the parasitic group was 2.3 mm (range; 1.6-3.8), and was larger than that of the control group (mean; 1.3 mm and range; 0-4.1mm) with statistical significance (P < 0.01). CONCLUSIONS: Multiphasic CT could demonstrate the presence of parasitic supply to HCCs from RIPA. Visualization of RIPA at the distal portion on CT would be a clue of parasitic supply from RIPA.