肝脏局灶性结节增生的典型与非典型MR表现及其病理基础

Focal nodular hyperplasia of the liver:correlation of MR imaging features with pathologic findings

目的：研究肝脏局灶性结节增生（FNH）的典型与非典型MR表现及其病理基础，探讨MRI对各型的诊断价值。方法：分析经手术病理证实的FNH28例（36个病灶）的典型与非典型MR表现，并与病理结果相对照。结果：①典型表现20例（28个病灶），大小在2．0-10．5em，TlWI上呈等／稍低信号，T2WI上呈等／稍高信号，增强扫描动、门脉期病变呈显著增强，延迟扫描呈等／略高信号，中心瘢痕出现率占42．9％（12／28例），于TlWI上呈低信号，T2WI上呈高信号，增强扫描呈延迟强化。组织学上有特征性的中央纤维瘢痕，由纤维结缔组织和扭曲的血管组成，并向外放射状形成许多纤维间隔，纤维间隔旁围绕以无明显异形性的肝细胞形成硬化样结节；②非典型表现8例（8个病灶），大小在1．5-8．5em，TlWI呈略高或低信号，T2Ⅵ呈不均匀高信号，增强扫描病灶强化不显著、不均匀，病灶内未见中心瘢痕或瘢痕不强化，出现假包膜等。镜下病变内毛细胆管扩张，其内纤维分隔较短、不连续，部分较大病灶内有出血、脂肪变及坏死，但无异型性肝细胞。结论：MRI能很好反映肝脏局灶性结节增生的典型与非典型表现的病理基础，具有高度的诊断特异性。

Objective：To analyze the typical, atypical MR imaging features, and the pathologic basis of focal nodular hyperplasia of the liver（FNH） in order to evaluate the value of MRI in the diagnosis of FNH. Methods：The MR imaging features of 28 patients with FNH proved by pathology were retrespeetively reviewed and correlated with pathologic findings. Results：①Typical manifestation （20 cas- es with 28 lesions） ： The size of the lesions ranging from 2.0 em to 10.5 em in diameter, hypo-intense or iso-intense in signal of the le- sions and lower intense in the central area of large lesions were found on T1-weighted images. On T2-weighted images, the lesions had a central scar showed hyper-intensity and a peripheral area showed iso-intensity in signal. After Gd-DTPA administration, marked enhanced homogenously was seen in these lesions during arterial phase and marked or moderate enhanced during portal or delayed phase. Typical central scar showed no enhancement during arterial phase and moderate or marked enhancement during portal or delayed phase in 12 cas- es. These lesions, proved by pathology, were composed of central scar with fibrous connective tissue and tortuous blood vessels, the fi- brous tissue radiated peripherally, dividing the mass into multiple, variably sized nodiules, simulating the pattern of cirrhosis. （2） Atypi- cal manifestation （8 cases） ： The size of the lesions ranging from 1.5 cm to 8.5 cm in diameter, on T1-weighted images, the signal of hy- per or hypo-intensity was found in these lesions. On T2-weighted images, the lesions showed hyper-intensity in signal. After Gd-UFPA administration, these lesions showed moderate enhanced heterogeneously with the hepatic parenchyma in signal. No central scar or un-en- hanced central scar was found in all these lesions and the pseudo-capsule showed slightly delayed enhancement in four cases. Microscopi- cally, multinodular proliferation of benign appearing hepato-eytes separated by bile-duet-containing short fibrous septal that radiatet from the central. Intemodular bile duct proliferationwes abundant and merged imperceptibly with the hepatocyte elements near the fibrous septa. In some larger lesions, steatesis, hemorrhage and necrosis were found in the central areas proved by pathology. Conclusion：There are significant correlation between the typical and atypical MRI findings and its pathology basis of focal nodular hyperplasia of the liver. Therefore, MIU is of high specificity for the diagnosis of FMH.