4DCT、PET-CT与MRI勾画胸段食管癌大体肿瘤体积比较研究

目的比较基于4DCT呼气末时相、18F-FDG PET-CT及T2加权(T2W)MRI所勾画胸段食管癌大体肿瘤体积(GTV)、位置及长度差异,探讨食管癌原发肿瘤GTV勾画时PET-CT与MRI图像结合的必要性。方法26例拟行同步放化疗的胸段食管癌患者序贯完成增强3DCT、增强4DCT、PET-CT、增强MRI胸部定位扫描,基于3DCT图像形变配准。分别基于3DCT、4DCT的呼气末时相、PET-CT SUV 2.5、T2W-MRI和DWI图像勾画GTV获得GTVCT、GTV50%、GTVPET2.5、GTVMRI和GTVDWI。结果GTVPET2.5大于GTV50%(P<0.001)和GTVMRI(P=0.008),而GTVMRI与GTV50%接近(P=0.439)。GTVMRI与GTV50%、GTVCT的适形指数(CI)大于GTVPET2.5与GTV50%、GTVCT的(P=0.004、P=0.039),GTVMRI与GTVPET2.5的CI明显小于GTVMRI、GTVPET2.5与GTV50%、GTVCT的(P=0.000~0.021)。镜检长度与GTVPET、GTVDWI长度相近(P>0.05),且GTVPET2.5与GTVDWI长度接近(P=0.072)。结论基于PET-CT SUV2.5与呼吸门控状态下T2W-MRI所勾画食管癌GTV和空间位置差异明显,PET-CT与MRI结合进行食管癌靶区勾画的必要性尚需探讨,但MRI-DWI可以代替PET-CT帮助基于CT图像勾画GTV时上下界的确定。

Comparison of gross target volumes based on four-dimensional CT,positron emission tomography-computed tomography and magnetic resonance imaging in thoracic esophageal cancer

Objective To investigate the application value of ¹⁸F-FDG PET-CT combined with MRI in the radiotherapy for esophageal carcinoma by comparing the differences in the gross target volume (GTV), position length delineated on the end expiratory (EE) phase of 4DCT, PET-CT and T2-weighted MRI (T2W-MRI). Methods Twenty-six patients with thoracic esophageal cancer scheduled to receive concurrent chemoradiotherapy sequentially underwent 3DCT, 4DCT,PET-CT and enhanced MRI for thoracic localization. All images were fused with the 3DCT images by deformable registration. GTVCT, GTV50% GTVPET2.5, GTVMRI and GTVDWI were delineated on 3DCT, the EE phase of 4DCT images, PET-CT with the thresholds of SUV≥2.5, T2W-MRI and diffusion-weighted images, respectively. Results GTVPET2.5 was significantly larger than GTV50% and GTVMRI (P<0.001 and P=0.008),whereas the volume of GTVMRI was similar to that of GTV50%(P=0.439). Significant differences were observed between the CI of GTVMRI to GTV50% and GTVPET2.5 to GTV50%(P=0.004). The conformity indexes (CIs) of GTVMRI to GTVCT and GTVPET2.5 to GTVCT were statistically significant (P=0.004 and P=0.039). The CI of GTVMRI to GTVPET2.5 was significantly smaller than that of GTVMRI to GTV50%, GTVMRI to GTVCT, GTVPET2.5 to GTV50% and GTVPET2.5 to GTVCT (P=0.000-0.021). The length of gastroscopy was similar to those of GTVPET2.5 and GTVDWI (both P>0.05), and there was no significant difference in the length between GTVPET2.5 and GTVDWI (P=0.072). Conclusion GTVMRI yields significantly different volume and poor spatial matching compared with GTVPET2.5. The application of PET-CT combined with MRI under respiratory gating system in the delineation of GTV should be used with caution in thoracic squamous esophageal cancer. MRI-DWI can replace PET-CT to help determine the upper and lower boundaries of GTV based on CT images.