中文摘要：

目的：探讨肝脏IgG4相关炎性假瘤（IPT）的MRI特征。方法回顾性分析经病理证实的9例肝脏IgG4相关IPT患者，患者均在病理检查前6周内行上腹部MRI平扫、增强及DWI检查。观察病灶的形态特征、MRI信号特征，测量病灶及肝组织的ADC值，采用配对t检验进行比较。结果9例肝脏IgG4相关IPT患者共11个病灶。8个病灶边界清楚，3个边界不清。7个病灶在肝包膜下分布。11个病灶在T1WI上均呈低信号。T2WI上8个病灶呈高信号。增强扫描5个呈渐进性强化，4个呈持续强化，其余2个为不典型的廓清模式，门静脉期、延迟期呈等、低信号。主要伴随征象包括：6个病灶延迟包膜样强化，7个病灶中央无强化区。病灶ADC值为（1.42±0.36）×10-3mm2/s，稍低于肝脏ADC值[肝脏为（1.55±0.31）×10-3mm2/s]，差异无统计学意义（t=0.78，P=0.46）。结论肝脏IgG4相关IPT的MRI表现多样，典型者T1WI低信号、T2WI稍高信号，增强后呈渐进性或持续高信号，伴延迟包膜样强化及中央无强化区。

英文摘要：

Objective To investigate the MRI features of hepatic IgG4-related inflammatory pseudotumor （IPT）. Methods Nine patients with 11 histopathologically proven IgG4-related hepatic IPTs were retrospectively analyzed. The clinical, morphological and MRI signal features on T1WI, T2WI, dynamic-enhanced, and diffusion-weighted imaging were assessed in detail and correlated with pathological findings. The paired t test was used to compare the ADC values of the tumors and the hepatic tissue. Results Hepatic IgG4-related IPT displayed certain MRI features. The dominant lesions were subcapsularly distributed （n=7） with a clear boundary （n=8）, which typically showed hypointensity on T1WI （n=11）, mild hyperintensity on T2WI （n=8）, progressive （n=5） or persistent （n=4） enhancement pattern. Accompanied signs included delayed capsule-like enhancement （n=6） and central nonenhanced areas （n=7）. Two lesions showed atypical wash-out pattern with iso or hypointensity on portal and delayed phases. In diffusion weighted imaging, all lesions were hyperintense, and the mean ADC value of the lesions [（1.42 ± 0.36） × 10-3mm2/s] was mildly lower than that of surrounding liver [（1.55±0.31）×10-3mm2/s], although no statistical differences were found（t=0.78, P=0.46）. Conclusions Hepatic IgG4-related IPTs display various MRI manifestations. The lesions normally show progressive enhancement pattern with diffuse homogeneous or heterogeneous hyperintensity, accompanied by delayed capsule-like enhancement and central nonenhanced areas.