Small Arterially Enhancing Hepatic Lesion in Cirrhotic Patients

Axial T1WI post contrast images in arterial and portovenous phase demonstrates a tiny enhancing nodule in hepatic segment V, which becomes isosignal to the liver on the portovenous phase. This nodule is occult on unenhanced T1WI and T2WI.

Hepatic Arterial Phase Detection of Small HCC

• Hepatic arterial phase imaging very important to detect small HCCs, which may be occult with other pulse sequences, at unenhanced or portovenous phase MR imaging
• Most HCCs demonstrate arterial enhancement and moderate T2 hyperintensity
• Some small HCCs, however, are seen only during the hepatic arterial phase

Differential Diagnosis of Small Arterially Enhancing Lesion in Cirrhotic Liver

• Hepatocellular carcinoma
• High-grade dysplastic nodule
• Focal nodular hyperplasia (FNH)
• Hemangioma
• Pseudolesions: arterial-portal venous shunt, aberrant venous drainage

Hepatic Pseudolesions

• Arterial enhancement but occult on portovenous and/or equilibrium phases, and at unenhanced T1- and T2-weighted MR imaging
• A retrospective study of 16 patients with 45 lesions showed that the majority (93%) of them were benign without any correlative pathologic findings. The remaining 7% that lesions were HCC, did have other concomitant HCC.
• It seems reasonable to follow these lesions closely with imaging to ensure they do not grow (if they grow, they are likely to represent HCC)

Our case - hepatic pseudolesion, the nodule has disappeared on follow-up MRI performed 3 months later.

Reference:

Holland AE, Hecht EM, Hahn WY, et al. Importance of small (equal or less than 20 mm) enhancing lesions seen only during the hepatic arterial phase at MR imaging of the cirrhotic liver: evaluation and comparison with whole explanted liver. Radiology 2005; 237:938-944.