磁共振胆胰管成像结合T_1加权成像对胆总管微小结石的诊断价值

Role of combining MR cholangiopancreatography and T_1WI in detecting micro-choledocholithiasis

目的:研究磁共振胰胆管水成像(MRCP)结合T^1加权成像(T^1WI)检测胆总管微小结石的诊断价值。对象与方法:2005年1月~2006年12月共有104例胆总管结石患者,其中56例胆总管微小结石(直径≤5mm)。术前作常规MRI检查(横断位T^1WI:TR/TE155ms/3.4ms,横断位和冠状位T^2WI:15000ms/81ms)。MRCP检查采用EXPRESS脂肪饱和序列,包括5组胆管路径的斜冠状45mm厚层成像采集、5mm薄层冠状成像采集(资源图像),来源于资源图像的最大信号投影重建图像。MR检查后1~5天内行胆总管外科手术或ERCP取石。分析胆总管微小结石的T^1WI和MRCP表现及MRCP和T^1WI对微小结石的检测、诊断。结果:56例胆总管微小结石,合并胆囊结石30例,胆囊切除7例。47例T^1WI胆总管微小结石高信号改变。MRCP显示阳性结石充盈缺损33例。T^1WI及T^1WI结合MRCP检出胆总管微小结石阳性率明显高于单纯MRCP检查,统计学比较有显著性差异(Fisher精确检验,P<0.01)。结论:在进行MRCP检查的同时,辅以T^1WI有助于提高胆总管微小结石的诊断敏感性。

Objective： To assess the role of adding T1WI to MR cholangiopancreatography in detecting micro-choledocholithiasis. Materials and Methods： A total 104 patients having choledocholithiasis from January 2005 to December 2006 were preoperatively performed by routine MRI and MRCP. Less than 5mm micro-stones of the common bile ducts were proved by surgery or ERCP following MRI scan by 1-5 days in 56/104 patients. Routine MRI scan included RF-FAST axial T1WI （TR/TE 155ms/3.4ms） and axial fast T2WI （TR/TE 15000ms/81ms） as well as coronal T2WI （TR/TE 15000ms/81ms）. EXPRESS fat-saturation imaging sequences of MRCP set included five 45mm thick-sections in oblique coronal planes in the course of the bile duct and 5mm thick no-gap coronal images（source images）. Maximum intensity projection（MIP） images were generated from the coronal source images. Features of common bile duct micro-calculi on T1WI and MRCP images and the sensitivities of T1WI and MRCP diagnosing for common bile duct micro-stones were analyzed. Results： Of these 56 patients, gallbladder stones were coexisted with choledocholithiasis in 30 patients and in whom 7 patients had a history records of cholecystectomy for gallstones. The signal intensities of common bile duct micro-calculi on T1WI were high relative to the low signal intensity of the bile in 47 patients. Filling-defects of hypo-intensity signals on MRCP images were shown in 33 patients. Both T1WI and combination MRCP with T1WI had a high sensitivity in detecting the common bile duct micro-calculi than MRCP alone. Statistics showed significant differences in detecting micro-stones between combination MRCP with T1WI and MRCP alone （Fisher exact test, P〈0.01）. Conclusion： Adding T1WI to MRCP will be helpful to provide a significant high sensitivity for diagnosing micro-calculi of the common bile ducts.