TREATMENT OF HEPATOCELLULAR-CARCINOMA WITH PERCUTANEOUS ETHANOL INJECTION - EVALUATION WITH CONTRAST-ENHANCED MR-IMAGING

OBJECTIVE. The aim of this study was to investigate the usefulness of unenhanced and enhanced MR imaging in evaluating the response of hepat ocellular carcinoma to percutaneous injection of ethanol. SUBJECTS AND METHODS. Thirty-one patients with 40 hepatocellular carcinomas less t han 5 cm in diameter were examined with MR imaging before and after pe rcutaneous injection of ethanol. Unenhanced T1- and T2-weighted and co ntrast-enhanced T1-weighted spin-echo images were obtained. CT and per cutaneous biopsy were performed 1 month after the final injection of e thanol and repeated at 6-month intervals to establish the outcome of t reatment: complete tumor necrosis was shown in 36 lesions and incomple te tumor necrosis was seen in four lesions. RESULTS. Of the 36 proved necrotic lesions, 31 showed homogeneously low signal intensity on T2-w eighted MR images obtained after treatment, owing to coagulative necro sis of the tumor. In the remaining five necrotic lesions, hypointense and hyperintense areas coexisted; the hyperintense areas were caused b y liquefactive necrotic material in two cases and by chronic inflammat ory tissue along the boundary of the necrotic area in three cases. Non e of the 36 necrotic lesions showed contrast enhancement on T1-weighte d images obtained after IV injection of gadopentetate dimeglumine. In the four lesions with incomplete necrosis, the viable portion of the t umor was identified as a hyperintense area on T2-weighted images and a s an enhancing area on contrast-enhanced T1-weighted images. No correl ation was found between lesion features on unenhanced T1-weighted imag es and outcome of therapy. CONCLUSION. Contrast-enhanced T1-weighted M R images allow a reliable evaluation of the effectiveness of treatment and are more accurate than unenhanced MR studies. Contrast-enhanced M R imaging may be considered a valuable alternative to contrast-enhance d CT in the follow-up of hepatocellular carcinomas treated with percut aneous injection of ethanol.