Small hepatocellular carcinoma treated with percutaneous ethanol injection: unenhanced and gadolinium-enhanced MR imaging follow-up

PURPOSE: To determine the value of magnetic resonance (MR) imaging in follow-up of small (< 3 cm) hepatocellular carcinoma treated with percutaneous ethanol injection (PEI). MATERIALS AND METHODS: Fifty-seven patients underwent MR imaging before and after PEI. At follow-up every 6 months, MR images were correlated with results of fine-needle aspiration biopsy (FNAB). In 12 patients, correlation with histologic findings in surgical specimens was possible. RESULTS: In 39 patients followed up for 24 months, the treated lesions showed hypointensity on unenhanced (T2-weighted) images and loss of enhancement on enhanced (T1-weighted) images. At 6-month follow-up in six patients, the lesions showed areas of hyperintensity on unenhanced images and enhancement on enhanced images. These lesions contained residual viable tumor at FNAB. Twelve patients underwent surgical resection after 6-month follow-up. Correct diagnosis of complete or partial tumor necrosis was made in nine of these 12 patients with enhanced images and in three with unenhanced images. CONCLUSION: Gadolinium-enhanced T1-weighted MR imaging is more accurate than unenhanced T2-weighted MR imaging in evaluation of PEI therapy