肝脏局灶性结节增生的MRI诊断

目的 分析和研究肝脏局灶性结节增生(FNH)的MRI表现及诊断价值。方法 回顾性分析24例30个经手术病理证实的FNH的平扫及动态增强扫描图像。24例中有4例又行肝特异性造影剂检查，包括2例锰福地匹三钠(Mn-DPDP)和2例超顺磁性氧化铁(SPIO))增强扫描。结果 22例为单发FNH，2例为多发。大小为1．0～6．0cm。24个病灶在T1WI上呈典型的等或略低信号，4个呈低信号，2个为略高信号。25个病灶在T2WI呈典型的等或略高信号，5个呈高信号。29个病灶的实质部分在动脉期明显强化，在门脉期和延迟期呈等或略高信号。1个病灶的实质部分在动脉元强化，而在延迟期变成等信号。2个病灶在延迟期出现增强的假包膜。21个病灶MRI平扫和动态增强扫描显示瘢痕，9个均未显示。瘢痕为T1WI低信号或等信号，T2WI高信号，增强后延迟强化，4个病灶动态增强扫描动脉期显示供血动脉影。使用Mn-DPDP后病灶为等或略高信号。使用SPIO后，病灶呈等信号。结论 多数FNH有典型MRI征象，综合使用平扫和动态增强扫描是正确诊断的关键。肝特异性造影剂对FNH的诊断有帮助。

MRI Diagnosis of Hepatic Focal Nodular Hyperplasia

Purpose To analyze and evaluate MRI findings of hepatic focal nodular hyperplasia(FNH). Methods The unenhanced and dynamic gadolinium-enhanced MR images of 30 FNHs from 24 patients proven by pathology were analyzed retrospectively.Four of 24 patients also undertook MRI with liver-speci-fic contrast agents,which was Mn-DPDP in 2 cases and SPIO in another 2 cases. Results FNH was solitary in 22 cases and multiple in 2 cases.Its size varied from 1.0-6.0 cm.On T1WI,24 lesions demonstra-ted typical isointensity or slightly hypointensity.Four lesions were hypointense.And 2 lesions presented slightly hyperintensity.On T2WI,25 lesions appeared typical isointensity or slightly hyperintensity.And 5 were hyperintense.Twenty-nine FNHs were markedly hyperintense in the arterial phase of dynamic contrast-enhanced MRI,and iso - or slightly hyperintense in the portal and delayed phases.One FNH did not enhance in the arterial phase but turned into isointensity in the delayed phase.Two FNHs were found surrounded by enhanced pseudocapsule in the delayed phases.The scars were shown by both unenhanced and enhanced MRI in 21 lesions,but were not visualized in the remaining 9 lesions.They were hypo - or isointense on T1WI and hyperintense on T2WI.The scars showed gradual enhancement,which becanme iso - or hyperintense on delayed images.In 4 patients,feeding arteries were depicted in the arterial phase.On MRI images enhanced with Mn-DPDP,FNH was isointense or slightly hyperintense.On SPIO-enhanced images FNH was isointense to the liver. Conclusions In most cases,FNH has typical MRI manifestations.The combined analysis of unenhanced and enhanced MRI is the key to correct diagnosis.Liver-specific contrast agents are helpful.