PET/CT图像融合在鼻咽癌适形放疗中的应用

Application of PET/CT image fusion for conformal radiotherapy in nasopharyngeal carcinoma

目的探讨鼻咽癌适形放疗中制定肿瘤靶区时正确使用PET/CT图像融合的方法及意义。方法对拟行根治性放疗的鼻咽癌患者在治疗前于同一固定体位完成MRI、PET、CT扫描。首先使用MRI图像融合CT进行肿瘤靶区的制定,而后使用PET/CT图像融合再次进行肿瘤靶区的制定,采用体积法和总靶区/共同靶区法评估GTV(包括鼻咽肿瘤GTV及受侵淋巴结GTVnd)的改变情况。结果在纳入研究的20例鼻咽癌患者中,有3例(15%)因分期改为M1期而采用以化疗为主的综合治疗;2例N0期和15例N1-3期患者行适形放疗。与MRI/CT勾画GTV相比,17例患者根据PET/CT勾画GTV均发生改变。体积法显示7例(41.18%)患者的GTV得到了缩小,10例(58.82%)得到了扩大,其中5例(29.41%)发生显著改变。总靶区/共同靶区法显示有6例(35.29%)患者的GTV发生显著改变。结论利用PET/CT将使鼻咽癌患者的分期更精确,有利于制定出更合理的治疗方案,PET/CT图像融合影响鼻咽癌适形放疗肿瘤靶区GTV的制定。

Objective To explore how to correctly use 18F-fluorodeoxyglucose positron e- mission tomography-computed tomography（PET/CT） image fusion on precise definition of the tar- get volumes of nasopharyngeal carcinoma in conformal radiotherapy. Methods Patients with na- sopharyngeal carcinoma were referred for radiotherapy before treatment. MRI, PET and CT scan- ning were performed. MRI image and CT image were fused for definition of the target volumes, PET/CT image fusion were made for definition of the target volumes. Finally changes of GTV （in- cluding nasopharyngeal carcinoma GTV and lymph node GTVnd） were assessed with the volume method and the total target area/common target method. Results In 20 nasopharyngeal carcinoma patients, the therapy plan changed in 3 cases （15 % ） with M1 stage, who were given chemotherapy subsequently, 2 cases with No stage and 17 cases with N1-3 stage were given IMRT. The volume analysis of the rest 17 patients who were finally given IMRT revealed that the PET/CT-basecl GTV were different from MRI / CT - based GTV . The volume method showed that in 7 patients （41.18%） the volume decreased, while in the other 10 patients （58.82%） the volume enlarged. The volume changed significantly in 5 patients （29.41% ）. Total volume/common volume method showed that GTV changed significantly in 6 patients （35.29%）. Conclusion PET/CT can induce more accurate staging and more suitable therapy plan. PET/CT image fusion will influence the GTV definition