Response of hepatocellular carcinoma to percutaneous ethanol injection: Ct and mr evaluation

Objective: 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). Materials and Methods: 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. Results: 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. Conclusion: 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.