平扫和动态增强MR诊断肝脏增生性结节

目的 总结增生性结节(DN)在MRI平扫及动态增强扫描中的特征. 资料与方法 回顾性分析行Gd-DTPA动态增强MR检查并经手术病理证实的DN共11例16个病灶,观察病灶的大小、信号强度、强化方式和时间,测量各序列病灶及周围肝组织的信号强度和背景噪声标准差,计算信噪比及其差值.绘制病灶和周围肝组织的时间-信号强度曲线. 结果 16个病灶中有4个表现为"结中结",中央结节为T1WI低、T2WI等或高信号,动态增强为速升速降或速升缓降型,周围为T1WI高、T2WI等或高信号,动态增强为缓慢上升型;余12个病灶在T1WI上高、等和低信号均有,在T2WI上为等信号和稍高信号,动态增强过程中动脉期强化较明显,门静脉期以等信号为主,延迟期为等及稍高信号, 未见呈低信号者.时间-信号强度曲线显示病灶为速升缓降型. 结论 "结中结"征象和动态增强早期强化、后期与周围肝组织类似信号的表现是DN的MRI特征.

Plain and Dynamic Enhanced MRI in Hepatic Dysplastic Nodules

Objectives To investigate the MR characteristics of dysplastic nodules(DN)in the plain scan and Gd DTPA dynamic enhanced MRI scan.Materials and methods 16 DN in 11 patients who received Gd DTPA dynamic enhanced magnetic resonance imaging were analyzed retrospectively.All the patients had been proved by pathologic examination.The size,capsule,signal intensity of lesions before and after enhancement,dynamic enhanced type and phase were all observed.Signal intensity of liver lesions,background on plain scanning and enhanced MR image,signal-to-noise ratios,contrast enhanced ratios were measured and analyzed.The time signal intensity curve was analyzed.Result The sign of "nodule in nodule" were shown in 4/16 lesions.The central nodules were shown hypointensity on T1WI and hyperintensity on T2WI with rapid initial and rapid decreasing.The surrounding tissue of them was hyperintensity on T1WI and iso or hyperintensity on T2WI with sustained enhancement slightly.The others were hypo,iso or hyperintensity on T1WI and iso or hyperintensity on T2WI,most of them were enhanced in artery phase and were isointensity in portal venous phase.In delayed phase,signals were mild hyper or isointensity compared with surrounding noncancerous parenchyma.The time signal intensity curve was rapid initially and decreasing slowly.Conclusion The MRI characteristic of DN include the sign of "odule in nodule" and rapid initially and decreasing slowly enhancement,and signal is isointensity compared with surrounding noncancerous parenchyma in delayed phase,which could be helpful in differentiating with other nodules of liver.