Hepatic pseudolymphoma: imaging features on dynamic contrast-enhanced MRI and diffusion-weighted imaging

To investigate dynamic contrast-enhanced (DCE) MR findings and diffusion-weighted imaging (DWI) characteristics of hepatic pseudolymphoma. The MR data of 20 lesions in 14 patients with histopathologically proven hepatic pseudolymphoma were retrospectively analyzed. All patients underwent dynamic gadopentetate dimeglumine-enhanced MR imaging and DWI. Morphologic characteristics and signal features on T1- and T2-weighted images (T1WI, T2WI), and DCE pattern were qualitatively evaluated. The quantitative analysis was performed for the size, the degree of enhancement on arterial phase, signal intensity (SI) of DWI, and apparent diffusion coefficient (ADC) values. The Wilcoxon signed ranks test was used for statistical analysis. The contour of all lesions was round. The lesion size was 0.7-2.8 cm (mean 1.3 +/- 0.5 cm). All lesions manifested as homogeneous hypointensity on T1WI and hyperintensity on T2WI. All lesions were shown as hypervascular with various enhancement patterns on DCE MR imaging. The presence of peripheral enhancement and pseudocapsule was observed in 7 and 4 lesions, respectively. SI of the hepatic pseudolymphoma was significantly lower than that of portal vein on arterial phase (P < 0.001) and the ADC was significantly lower than that of spleen (P = 0.012). A homogeneous nodule with small size (< 2 cm), manifestation of hypervascular with lower SI than that of portal vein on arterial phase and lower ADC values than that of spleen are the common MR features of hepatic pseudolymphoma.