MRI allows the identification of a wide spectrum of appearances of untreated liver metastases. The extent and pattern of enhancement of various histologic types of tumor are depicted on MRI.

Purpose: To assess MR imaging findings and clinical manifestations of diffuse-type hepatocellular carcinoma (HCC). Materials and Methods:We retrospectively reviewed our experience with diffuse HCC from November 1994 to October 2001. MR imaging findings and clinical features were assessed.Results: Twenty-two consecutive patients with diffuse-type HCC (19 men and three women, age range 16 -80 years [mean, 52 years]) were identified in a review of liver MR studies. This represented 13% of all patients with HCC imaged during this time period. Diffuse HCC showed a permeative, infiltrative pattern with ill-defined borders and no evidence of convex margination in all cases. At least 50% of the liver volume was involved with tumor. Diffuse-type HCC showed hypointensity in 15 patients, mixed intensity in three, and isointensity in four on T1-weighted images; heterogeneous hyperintensity in 16 patients; and homogeneous hyperintensity in six on T2-weighted MR images. Diffuse-type HCC showed patchy enhancement in 12 patients, miliary enhancement in nine, and minimal enhancement in one on postcontrast early-phase images, and showed heterogeneous washout in all patients on postcontrast late-phase images. Proximal portal venous tumor thrombosis was seen in all patients. Serum ␣-fetoprotein (AFP) value was elevated (Ͼ10 ng/mL) in 14 of 18 patients, and 13 showed a value greater than 500 ng/mL. The four patients who did not have elevated AFP had tumors which were indistinguishable from those in patients with elevated AFP; they also did not have a distinctive clinical history.Conclusion: Diffuse-type HCC was typically seen as an extensive, heterogeneous permeative hepatic tumor, with portal venous tumor thrombosis on MR images in all cases. Early enhancement, observed as patchy in 12 and miliary in nine of 22 patients, was a distinctive imaging feature. Elevated serum AFP value was a common finding; however, 22% had normal values.

MRI findings after ablation are dependent on the treatment modality and the length of time between the procedure and follow-up examination.

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