增强扫描对基于4DCT胸段食管癌GTV勾画及IGTV构建的影响

目的 探讨增强扫描与否对基于4DCT勾画的胸段食管癌原发肿瘤各时相GTV差异及对IGTV构建的影响。方法 25例胸段食管癌患者,胸上段8例、胸中段9例、胸下段8例,自由呼吸状态下序贯完成普通4DCT与增强4DCT扫描,同一勾画者按照同一标准先在平扫4DCT各图像上勾画GTV并构建相应IGTV。1个月后同一勾画者再在增强4DCT图像上勾画GTV并构建相应IGTV。结果 基于增强扫描图像勾画的靶区变异系数小于平扫图像勾画的(P=0.000),但胸上、下段食管癌患者二者的GTVz轴长度、GTV、IGTV均相近(P=0.529、0.110;P=0.158、0.416;P=0.147、0.615),而对胸中段食管癌患者二者的GTVz轴长度、GTV、IGTV不同(P=0.005、0.035、0.021)。结论 对胸中段食管癌患者,增强4DCT扫描可减小靶区勾画误差并可构建相对精确的IGTV,而对胸上、下段食管癌患者靶区勾画及IGTV构建无显著影响。

Impact of contrast-enhanced 4DCT scan on delineating GTV and constructing IGTV in thoracic esophageal cancer

Objective To investigate the difference between conventional and contrast-enhanced four-dimensional computed tomography (4DCT) scans in delineating the gross tumor volume (GTV) in different phases and constructing the internal gross tumor volume (IGTV) in primary thoracic esophageal cancer. Methods Twenty-five patients with thoracic esophageal cancer, including 8 upper-thoracic, 9 middle-thoracic, and 8 lower-thoracic, sequentially underwent conventional and contrast-enhanced 4DCT scans during normal breathing. The GTVs were delineated by a physician under the same standard using conventional plain 4DCT images, and the IGTVs were constructed accordingly. After one month, the GTVs were delineated by contrast-enhanced 4DCT images and IGTVs were constructed by the same physician. Results The coefficient of variation for the target volume based on the contrast-enhanced 4DCT images was smaller than that based on the plain 4DCT images. There were no significant differences in the length of the z axis of GTV, GTV, and IGTV between contrast-enhanced and plain 4DCT images in patients with upper-and lower-thoracic esophageal cancer (P=0.529 and 0.110;P=0.158 and 0.416;P=0.147 and 0.615). However, in patients with middle-thoracic esophageal cancer, the length of the z axis of GTV, GTV, and IGTV were significantly different between contrast-enhanced and plain 4DCT images (P=0.005, 0.035, and 0.021, respectively). Conclusions Contrast-enhanced 4DCT scan can reduce the error in delineating the target volume and construct a more accurate IGTV for patients with middle-thoracic esophageal cancer. However, it has no significant benefit in patients with upper-and lower-thoracic esophageal cancer.