磁共振扩散加权成像对直肠癌的显示及其恶性程度评估的初步研究  

Preliminary study of diffusion weighted imaging in detecting and evaluating the prognosis of rectal carcinoma

作　　者：亓俊霞[1] 白人驹[2] 于长路[1] 贾科峰[1] 张翔[1] 

机构地区：[1]天津市第三中心医院放射科,天津300170 [2]天津医科大学总医院

出　　处：《实用放射学杂志》2013年第3期400-404,共5页Journal of Practical Radiology

摘　　要：目的 本研究旨在选择直肠癌扩散加权成像（DWI）的合适b值，并探讨DWI成像的表观弥散系数（ADC）值在肿瘤恶性程度预测方面的价值。方法 对首诊直肠癌的40例患者行前瞻性MR扫描研究。采用单次激发SE-EPI序列，取0 s/mm2和500、800 s/mm2与1 000 s/mm2 3组b值行MR扩散加权成像，获得各b值下直肠癌病变的DWI图、ADC图及指数化ADC（eADC）图。结果 不同b值的DWI图像上，直肠癌病变均表现为高信号，并且随着b值的升高，病变信号强度下降；不同b值下，病变ADC值不同；同一b值下，不同分化程度间病变的ADC值不同；经ROC曲线分析，各b值下，病变的ADC值均可作为评估肿瘤分化程度的有效指标，且以选取b值为1 000 s/mm2时，曲线下面积最大，即诊断效能最高，ADC值的最佳阈值为0.600×10-3 mm2/s。结论 使用b值为1 000 s/mm2的DWI序列检查利于直肠癌病变的早期诊断。DWI表现及所测得的ADC值在一定程度上能够反映肿瘤的分化状况，有助于术前预测肿瘤的恶性程度。Objective To choose the optimal b value of diffusion weighted imaging （ DWI ） for rectal carcinoma , and mainly to evaluate the value of apparent diffusion coefficient（ADC） in the prognosis of rectal carcinoma. Methods Forty patients were enrolled in this study. SE-EPI-DWI sequence was performed with three different b values（0,500,800,1000 s/mm^2）. DWl images with differ- ent b values were acquired, the ADC and eADC images were obtained by corresponding post processing. Results On DWI images with different b values, the rectal carcinomas were all of high signal and the signal attenuated with b value increasing. The ADC values were different between different b values. With each b value, the discrepancies of the ADC values between different differentia tions of rectal carcinoma are all statistically different. By receiver operating characteristic（ROC） curve analyzing , the threshold values of ADC obtained from each b value were contributory to differentiate the different differentiations in rectal carcinoma , especially with b value of 1000 s/mm^2 ,the area under ROC curve was the largest;the optimal threshold values of ADC was 0. 600× 10 ^-3 mm^2/s. Conclusion The optimal b value on DWI for the early diagnosis of rectal carcinoma is 1 000 s/mm^2 in this study . Features on DWI and ADC values are both helpful for differentiating the tumors with different differentiations on some extent, so it can be used to prognose the malignancy before operation.

关 键 词：直肠癌 扩散加权成像 表观扩散系数 信噪比 对比噪声比 

分 类 号：R735.37[医药卫生—肿瘤] R445.2[医药卫生—临床医学]