Imaging features of hepatic inflammatory pseudotumor: distinction from colorectal liver metastasis using gadoxetate disodium-enhanced magnetic resonance imaging

To identify gadoxetate disodium-enhanced MRI features distinguishing hepatic IPT from CLM.

From February 2008 to December 2019, 162 lesions (IPT, n = 31 and CLM, n = 131) from 94 patients (mean age 65.1 ± 12.2 years; 65 men and 29 women) were retrospectively assessed for the presence or absence of obscure boundary, rim enhancement on arterial phase (AP), persistent rim enhancement during AP to transitional phase (TP), blood vessel penetration, peritumoral parenchymal enhancement on AP, peritumoral parenchymal hypointensity on hepatobiliary phase (HBP), peritumoral parenchymal hyperintensity on T2-weighted imaging (T2WI), biliary dilatation, central hypointensity with a relatively hyperintense periphery on HBP, peripheral hyperintensity on diffusion-weighted imaging (DWI) and T2WI, and lesion to liver signal intensity ratio (SIR_lesion/liver) on HBP and DWI. Relevant features for differentiating between ITP and CLM were identified by univariate and multivariate analyses.

Univariate analysis revealed significantly higher frequencies of the following features in IPT than CLM: younger age, obscure boundary, blood vessel penetration, central hypointensity with a relatively hyperintense periphery on HBP, higher SIR_lesion/liver on HBP, and lower SIR_lesion/liver on DWI (P < 0.001‒0.035). Rim enhancement on AP and persistent rim enhancement during AP to TP were significantly more common in CLM than in IPT (P ≤ 0.001). Multivariate analysis revealed that a central hypointensity with a relatively peripheral hyperintensity on HBP, higher SIR_lesion/liver on HBP, and lower SIR_lesion/liver on DWI were predictive of IPT (P = 0.003‒0.039).

Central hypointensity with a relatively peripheral hyperintensity on HBP and SIR_lesion/liver on HBP and DWI may be reliable gadoxetate disodium-enhanced MRI features for distinguishing IPT from CLM.