肝脏局灶性结节增生的平扫及动态增强MRI表现

Precontrast and dynamic contrast enhanced MRI findings of hepatic focal noduar hyperplasia

目的分析肝脏局灶性结节增生(FNH)MRI平扫及动态增强表现,提高对该病的认识和诊断水平。方法回顾性分析19例共20个经手术病理证实的FNH病灶,所有病例均行MRI平扫及动态增强检查,对病灶的MRI特征进行评价。结果18例为单发病灶,1例为2个病灶,病灶位于左外叶6个、左内叶9个、右后叶4个、尾状叶1个;病灶大小平均为3.6cm×4.5cm;与肝实质比较,平扫T1WI序列为稍低信号、T2WI序列为稍高信号者16个,T1WI及T2WI为等信号者4个,9个病灶内见瘢痕,呈长T1长T2信号。动态增强扫描动脉期18个病灶明显强化,1个病灶中等程度强化,1个病灶周边轻度强化,2个病灶周边出现扭曲血管;门脉期信号高于周围肝实质者17个,等信号2个,信号相对低于肝实质1个;延迟期仍为高信号者14个,另5个表现为等信号,1个为稍低信号;门脉期和延迟期有3个病灶周围可见细环状包膜;15个病灶增强后其内可见瘢痕影,瘢痕于动脉期、门脉期均为低信号,延迟强化者4例。所有病灶周围静脉显示良好。结论MRI平扫及动态增强扫描能较好地显示FNH的内部结构和信号特点,反映病灶的血供特点和病理特征,有助于和肝脏其他病变相鉴别。

Objective To evaluate the precontrast and dynamic contrast enhanced MRI findings of hepatic focal nodular hyperplasia （FNH） and improve the knowledge of the disease. Methods Nineteen cases including 20 pathologically confirmed FNH lesions were analyzed retrospectively. Precontrast and dynamic contrast enhanced MR examinations were performed in all the cases. The MR imaging features of FNH lesions were studied subsequently. Results Eighteen cases occurred solitary lesion and 1 case occurred multiple lesions. 6 lesions distributed in the left external lobe, 9 in the left internal lobe, 4 in the right posterior lobe and 1 in the caudate lobe. The average diameter of the lesions was 3.6 cm×4.5 cm. On precontrast MR images, 16 lesions were slight hypointense on TlWI and hyperintense on T2WI relative to the surrounding liver. 4 lesions were isointensity on T1WI and T2WI. A central scar was noted in 9 lesions on unenhanced images, appearing hypointense on TlWI and hyperintense on T2WI. After gadolinium administration, 18 lesions enhanced markedly and 1 enhanced moderately, 1 enhanced slightly in the rim on arterial phase, dilated arteries were detected around 2 leslons; 17 demonstrated hyperintensity, 2 were isointense and 1 was hypointense on portal vein phase; 14 prolonged with hyperintensity and 5 were isointensive and l was hypointensive relative to liver on the delayed phase. The thin ring capsule was noted in 3 lesions on portal vein and delayed phase. 15 lesions showed central scar on dynamic contrast enhanced images, central scar displayed hypointensity on arterial and portal vein phase,4 enhanced on delayed phase. Veins surrounding the lesions demonstrated well. Conclusion Precontrast and dynamic contrast enhanced MRI could disclose inner structure and signal characteristics of FNH, demon- strate the pathologic features of the lesion and its blood supply, therefore can contribute to the differentiation between other hepatic lesions.