肝腺瘤的平扫和动态增强MRI表现

Hepatocellular adenoma: precontrast and dynamic contrast enhanced MRI findings

目的探讨平扫和动态增强MRI对肝腺瘤的诊断价值。方法经手术病理证实的5例单发肝腺瘤和2例糖原累积症合并多发肝腺瘤行MR检查，对病灶大小、包膜、平扫和增强信号表现进行评价。结果5例单发病灶均较大，平均6．8cm×8．9cm。与肝实质比较，T1WI序列等信号，T2WI序列高信号，病灶内见液化坏死、出血信号区，周缘见低信号包膜；增强后动脉期3例病灶明显强化，2例病灶轻一中度强化；门脉期病灶高于周围肝实质3例、等于和低于各1例；延迟期病灶高于周围肝实质1例、等于和低于周围肝实质各2例。周缘包膜门脉期和延迟期强化4例，无强化1例。2例多发病灶大小不一，MR平扫较大病灶（直径≥3cm）与上述单发病灶表现相似；小病灶（直径〈3cm）相对于肝实质呈高信号或等信号，周缘基本无包膜；各病灶增强后动脉期明显强化，门脉期和延迟期高于或等于周围肝实质。结论肝腺瘤无确定一致的MRI表现，但在平扫和增强期检查的特征性表现有助于它与肝脏内其他肿瘤鉴别。

Objective To investigate the multiphase enhancement of MR Imaging. Methods appearance of hepatocellular adenoma on pre- and MR Imaging were performed in 5 patients with solitary hepatic adenoma and 2 patients with multiple hepatic adenomas with type I glycogen storage disease. Breathholding precontrast scans of TIWI and T2WI sequence were obtained in each patient, along with hepatic arterial-dominant phase （HAP）, portal venous-dominant phase （PVP） and delayed-phase scans after intravenous contrast material injection. The MR Imaging features of hepatocellular adenoma for the size, capsule and signal intensity were studied retrospectively. Results The average diameter of 5 solitary lesions was 6. 8 cm x 8.9 cm. On precontrast Tl WI MR images, 5 lesions were isointense relative to the surrounding liver, with areas of hypointensity or hyperintensity due to necrosis or hemorrhage; heterogeneous hyperintensity on T2WI MR images, with capsules not clearly demarcated compared with thin hypointensity capsules on TIWI MR images. 3 enhanced markedly and 2 enhanced mild or moderately on HAP; 3 demonstrated hyperintensity, 1 was isointense and 1 was hypointense on PVP; 1 prolonged with hyperintensity and 2 were isotensive and 2 were hypointensive relative to liver on the delayed phase. 4 lesions demonstrated enhancing capsule like rims on PVP and delayed phase. The MR findings of the larger multiple hepatocellular adenomas were similar with the above 5 solitary lesions; the smaller lesions （ 〈 3 cm） were slightly hyperintense or isointensense on the precontrast sequences, and all lesions enhanced markedly on HAP; prolonged with hyperintensity or isointensity on PVP and delayed phase. Conclusion Although HCA have not common MRimaging manifestations, some characteristic features at muhiphase MR Imaging may allow their distinction from other hepatic masses.