Radiographic procedures

For the diagnosis of HCC at study entry, intravenous contrast-enhanced dynamic CT was performed on an outpatient basis using an X-ray CT device with 4, 8, or 16 detector rows (Aquilion 4/16; Toshiba, Tokyo, Japan; LightSpeed Qx/I, LightSpeed Ultra; GE Healthcare, Milwaukee, WI). Images were obtained during the early arterial, late arterial, and equilibrium phases at 28, 40, and 120s after starting the intravenous bolus injection of iopamidol (Iopamiron; Nihon Schering, Osaka, Japan) or iohexol (Omnipaque; Daiichi Sankyo, Tokyo, Japan) at a rate of 2.3–3.3ml/s with a power injector. The total dose of iodine was 0.7g/kg body weight, with an upper limit of 37g iodine. The injection time for the contrast material was 30s. Images were reconstructed with a section thickness of 2.5mm and a reconstruction interval of 1.5mm, and were reviewed by experienced radiologists.

CTHA/CTAP was performed on an inpatient basis. First, a 4-Fr modified Shepherd-hook catheter and a 4-Fr hepatic-curve catheter were placed in the celiac artery and superior mesenteric artery, respectively, through bilateral femoral arteries, according to Seldinger's method. Digital subtraction angiography was performed from the celiac artery to evaluate hepatic artery anatomy. A microcatheter was inserted through the 4-Fr catheter and placed in the proper or common hepatic artery for hepatic arteriography.

The CTAP catheter was placed in the superior mesenteric artery in all cases. In the case of a replaced or accessory right hepatic artery, the catheter was inserted well beyond the origin of the hepatic artery to prevent contrast medium overflow into the hepatic artery. Less than 30ml of contrast agent, which was diluted to 100mg I/ml, was used before the CTHA/CTAP study. First, CTAP was performed using 90ml nonionic contrast medium diluted to 100mg I/ml, and then CT scanning was performed 30s after the start of the injection at a rate of 3.0ml/s. Multidetector-row CT images were obtained during a single breath hold in a longitudinal direction with collimation of 1mm, table speed of 30mm/s, 120kVp, and 300mAs. CTHA was performed at least 5min after CTAP, using the same parameters. CT scanning was performed at 10 and 45s after the start of contrast medium injection into the microcatheter at a rate of 2.0–2.5ml/s. A total of 30–50ml contrast agent diluted to 100mg I/ml was used. When the liver was perfused by two or more hepatic arteries such as a replaced right hepatic artery, accessory right hepatic artery, or left hepatic artery downstream of the left gastric artery, CTHA was performed from each of the respective arteries. A diagnosis of typical HCC on CTHA/CTAP was defined as a round hypervascular nodule on CTHA with a defect on CTAP, accompanied by corona enhancement during the second phase of CTHA or hypoattenuation during the equilibrium phase of prior dynamic CT ((10,29)).

TACE was additionally performed when ≥4 HCC nodules were detected on CTHA/CTAP, as evaluated at the time by the operating radiologist. The procedure used 3.0ml contrast medium, 30mg doxorubicin (Adriacin; Kyowahakko Kirin, Tokyo, Japan), and 3.0ml iodized oil (Lipiodol Ultra-Fluid; Guerbet Japan, Tokyo, Japan). The amounts of contrast medium and iodized oil in this suspension were arbitrarily adjusted according to tumor size. This agent was injected into each feeder of the HCC, followed by infusion of 2-mm-diameter gelatin sponge particles (Gelpart; Nihonkayaku, Tokyo, Japan).

CTHA/CTAP images were scrutinized by two experienced radiologists, who made the final diagnosis. The radiologists were not blinded to information regarding the preceding conventional dynamic CT. Preceding intravenous contrast-enhanced dynamic CT was retrospectively reviewed for nodules newly diagnosed by CTHA/CTAP to determine whether the nodules could have been detected on dynamic CT.