肝再生性结节的MRI诊断

目的:总结肝再生性结节(RN)的MRI平扫及动态增强的表现,以与其它结节进行鉴别.方法:搜集行Gd-DTPA动态增强磁共振检查的RN病例共30例,全部病例均经手术切除病理或穿刺活检证实.MRI均行平扫、动态增强及延迟增强扫描,分析结节的信号特征及动态增强曲线.结果:肝再生性结节包括弥漫分布的小结节18例(铁质沉着性结节6例和非铁质沉着性结节12例)和大结节12例17个病灶.铁质沉着性结节在增强各期均无强化,时间-信号强度曲线较平直;大部分非铁质沉着性结节在T1WI上和T2WI上均为中等信号,周围纤维间隔为偏低信号,动态及延迟增强扫描结节轻度强化,时间-信号强度曲线与正常肝组织类似.本组所选大结节为直径大于0.5 cm、T1WI高信号、T2WI低信号的病灶,其中10个病灶(占58.8%)在T1W/WATS上信号高于T1W/IP.动态增强各期病灶无明显强化,时间-信号强度曲线显示病灶的曲线为缓慢上升型.结论:肝再生性结节有不同类型及表现形式,其中孤立的大结节型RN需与肝内其它结节鉴别.

Gd-DTPA Dynamic Enhanced MRI in Hepatic Cirrhotic Nodules

Objectives:To investigate the MR characteristics of regenerative nodules(RN)in the plain scan and Gd-DTPA dynamic enhanced scan and to search the diagnostic key points for differentiating from other nodules in the liver.Methods:30 cases of patients with hepatic regenerative nodules who underwent Gd-DTPA dynamic enhanced magnetic resonance imaging were analyzed retrospectively.Diagnoses of all the patients were proved by pathologic examination or by puncture biopsy.Routine plain scanning included T1/WATS,T1/IP and T2WI in the axial plane and T1/IP in the coronal,3D dynamic WATS were performed.The size,capsule,signal intensity of lesions before and after enhancement,dynamic enhanced type and phase were all observed.The time-signal intensity curve was analyzed.Results:RNs included multiple micronodular cirrhosis in 18 cases(including siderotic or iron-containing nodules in 6 and nonsiderotic in 12)and macroregenerative nodules in 12 patients with 17 lesions.Siderotic nodules were hypo-intensity on T1 and T2 weighted imaging,and no enhancement in dynamic enhancement.Most nonsiderotic RNs were isointensity compared with surrounding hepatical parenchyma and had same pattern in dynamic enhancement.The macroregenerative nodules in our group were hyperintensity on T1 weighted imaging and hypo-intensity on T2.The intensity of lesions was higher on T1W/WATS than on T1W/IP in 10 lesions.The enhancement was sustained enhancement slightly.Conclusion:RNs had different types and had three patterns of appearances in MRI.Macroregenerative nodules need to be differentiated from some dysplastic nodules and small hepatocellular carcinoma.