Response of hepatocellular carcinoma to percutaneous ethanol injection: CT and MR evaluation

The aim of the present study was to perform a comparative assessment of the contribution of imaging examinations to the evaluation of the response of hepatocellular carcinoma (HCC) to percutaneous ethanol injection (PEI).

Twenty-five small HCCs (< 5 cm in diameter) were treated by means of PEI. The outcome of treatment, established on the basis of percutaneous biopsy and a 10 to 26 month follow-up, was complete necrosis in 23 of 25 cases and tumor persistence in 2 of 25.

While ultrasound proved to be unable to distinguish posttreatment fibrosis from persisting neoplastic tissue, contrast-enhanced CT correctly identified the two cases of treatment failure, which showed the presence of enhancing areas within the lesion. The remaining 23 cases displayed a hypodense appearance, with no contrast enhancement on CT. Magnetic resonance demonstrated ethanol-induced coagulative necrosis as marked hypointensity on T2-weighted images in 21 of 25 cases. In four cases areas of high signal intensity on T2-weighted images within the nodule were observed after PEI: In two cases they were associated with tumor persistence, and in the other two with the presence of liquefactive necrosis.

Our results demonstrate that different necrotic phenomena following ethanol injection therapy of HCCs may result in variable MR appearance. Although the location of hyperintense areas may suggest a differential diagnosis (central hyperintensity being more likely due to necrosis), CT remains the more reliable technique in the assessment of the response of HCC to PEI.