磁共振胆胰管成像结合T1加权成像对胆总管微小结石的诊断价值

目的：研究磁共振胰胆管水成像（MRCP）结合T1加权成像（T1WI）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T1WI：TR/TE 155ms/3.4ms，横断位和冠状位T2WI：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T1WI和MRCP表现及MRCP和T1WI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T1WI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。T1WI及T1WI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T1WI有助于提高胆总管微小结石的诊断敏感性。

Role of combining MR cholangiopancreatography and T1WI in detecting micro-choledocholithiasis

Objective: To assess the role of adding T~1WI 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 T~1WI(TR/TE 155ms/3.4ms) and axial fast T2WI(TR/TE 15000ms/81ms) as well as coronal T~2WI(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 T~1WI and MRCP images and the sensitivities of T~1WI 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 T~1WI 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 T~1WI and combination MRCP with T~1WI 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 T~1WI and MRCP alone(Fisher exact test, P<0.01). Conclusion: Adding T~1WI to MRCP will be helpful to provide a significant high sensitivity for diagnosing micro-calculi of the common bile ducts.