Abstract: Objective The aim of this study was to summarize imaging feature of atypical hepatic abscesses (AHA) and intrahepatic metastases (IMT) by MR and diffusion-weighted imaging (DWI). Methods 30 patients with AHA and 50 patients with IMT were admitted to our hospital between January 2020 and January 2025, and all underwent conventional and enhanced MR scan with DWI quantitative parameters recorded. Results Diameter and multiple lesion percentage in AHA lesions were(3.4±1.0)cm and 26.7%, both much smaller or lower than [(4.4±1.3)cm and 62.0%, respectively, P<0.05], while percentages of distinct edge, intralesional homogeneous signal at T2WI, capsule-like structures and perilesional hepatic parenchymal reaction were 76.7%, 66.7%, 46.7% and 50.0%, all much higher than 42.0%, 36.0%, 18.0% and 14.0%(P<0.05) in IMT lesions; AHA lesion exhibited 40.0% of ring-like enhancement at arterial phase, while IMT showed irregular or nodular enhancement for 72.0%; AHA lesions were homogeneously enhanced in 36.7% and 60.0% at portal and delayed phases, both much higher than 16.0% and 30.0%(P<0.05) in IMT lesion, and IMT presented central necrosis in 58.0%; mean ADC (ADCmean) and relative ADC (rADC) at DWI sequence in AHA were(1.7±0.4)×10^-3mm²/s and (0.7±0.2)×10^-3mm²/s, both significantly greater than [(1.0±0.3)×10^-3mm²/s and (0.4±0.1)×10^-3mm²/s, respectively, P<0.05], while lesion-to-liver signal ratio and contrast-to-noise ratio were (1.9±0.3) and (18.4±3.2), both significantly greater than [(2.4±0.3) and (24.7±4.1), respectively, P<0.05] in IMT lesions. Conclusion AHA and IMT exhibit significantly different MRI features, which might help differentiate diagnosis of the two different entities, especially based on clinical materials.

Key words: Atypical hepatic abscess, Intrahepatic metastasis, Magnetic resonance imaging, Diffusion-weighted imaging, Differentiation diagnosis