MRI影像与CT影像融合技术在局部晚期食管癌放疗靶区勾画中的应用研究

目的:探讨磁共振弥散加权影像（DWI）联合T2WI影像融合电子计算机断层扫描（CT）影像技术在局部晚期食管癌放疗靶区勾画中的应用价值。方法:选取2018年3月-2019年3月本院收治的食管癌局部晚期患者31例为研究对象，患者均在放疗前行CT和MRI常规及DWI检查，采用Eclipse治疗计划系统将两种影像学图片融合，由3名放疗科医师在CT图像及融合图像上进行放疗靶区勾画，分别记作A、B、C组。比较两种勾画方案勾画食管癌大体肿瘤靶区(GTV)和临床靶区（CTV）体积、长度、厚度及其变异系数CV值和Ratio值（最大值/最小值），分析CT图像与融合图像GTV和CTV体积差异的原因。结果: 以CT为基础勾画的GTV和CTV体积、长度、厚度均大于以融合图像为基础勾画，差异有统计学意义（均P＜0.05）。3名放疗医师以CT图像为基础勾画的各项指标CV值、Ratio均大于以融合图像为基础勾画，差异有统计学意义（均P＜0.05）；多因素分析，颈段食管癌、T4期食管癌是影响CT图像与融合图像GTV和CTV体积差异的独立相关因素（均P＜0.05）。结论:相对于CT图像，DWI联合T2WI影像融合CT影像技术能有效指导食管癌放疗靶区勾画及不同医师靶区勾画一致性。

Application of MRI and CT image fusion technology in target volume delineation of radiotherapy for local advanced esophageal cancer

Objective: To explore the application value of magnetic resonance diffusion weighted imaging(DWI) combined with T2WI image fusion computed tomography(CT) image technology in target volume delineation of radiotherapy for local advanced esophageal cancer. Methods: 31 patients with local advanced esophageal cancer in our hospital from March 2018 to March 2019 were enrolled in the study. The patients were examined by completed CT, conventional MRI and DWI before radiotherapy. The obtained images were fused by Eclipse treatment planning system. The target volume of radiotherapy was delineated on both CT images and the fused images by 3 radiologists. The volume, length, thickness, coefficient of variation (CV) and ratio value(ratio of the maximum value to the minimum value) of gross target volume (GTV) and clinic target volume (CTV) in the two plans were compared. The causes of differences in GTV and CTV volume between CT images and fused images were analyzed. Results: The volume, length and thickness of GTV and CTV based on CT were significantly larger than those based on fused images(all P<0.05). The CV and ratio values of each index delineated by the 3 radiologists based on the CT images were significantly larger than those based on the fused images(all P<0.05). Multivariate analysis showed that cervical esophageal cancer and esophageal cancer at stage T4 were independent correlation factors for differences in GTV and CTV of CT images and fused images(all P<0.05). Conclusion: Compared with CT images, DWI combined with T2WI image fusion CT image technology can be used to guide target volume delineation of radiotherapy for local advanced esophageal cancer and improve the consistency among different physicians.