鼻咽癌调强适形放疗MRI-CT图像融合三种配准方法的精度比较

摘要

Objective: To compare the accuracy of MRI-CT fusion with three image registration methods for IMRT in na-sopharyngeal carcinoma. Methods: From November 2011 to April 2012,16 NPC patients according to Chinese 2008 staging system were treated by radical radiotherapy with IMRT technique in our institute. With consistency of immobilization, the MRI-CT image registration with mutual information ,extenal point,MI+ Extenal point+manual were made for each mass, the positional error of 10 groups anatomic landmark, the fusion index (FI) and the sum of distance of center of geometry(Dtotal) were analyzed to evaluated the registration accuracy.one-way ANOVA was used for comparison among three methods. Results: The positional errors in x,y axis with three methods were (3.05±1.22,2.71±1.01), (2.05±0.55,1.8±0.5), (0.86±0.12, 1.01 ±0.13), (F=31.96,P<0.001;F=26.991,P<0.001)) respectively;FI were 0.549 ±0.203,0.742 ±0.12,0.898 ±0.09 (F=23.03, P<0.001), respectively; Dtotal were 11.23±3.58,6.52±2.55,3.57±0.79 (F=23.03,P<0.001), respectively. Conclusions: Byrne method of MI+Extenal point+manual,MRI-CT has the best registration accuracy.%目的:探讨鼻咽癌调强适形放疗MRI-CT图像融合的配准方法.方法:16例首程治疗的鼻咽癌患者在获取CT及MRI图像后,分别采用互信息法(MI法)、外部标记法及MI+标记+手动微调的综合法三种方法行MRI-CT影像融合,由2位经验丰富的中高年资放疗科医师共同勾画鼻咽部GTV,分别单独根据CT图像、MRI图像及融合图像勾画GTVnxc、GTVnxm及GTVnxcm,然后对GTVnxc与GTVnxm分别进行与、或操作,生成新的靶区GTVnxc&m,GTVnxc|m,根据10组解剖标记x、y向位置差、靶区融合指数(FI)及中心距离和法Dtotal分别评价三种配准方法的融合精度,用单因素方差检验分析各组差异.结果:三种配准方法在10组解剖标记的x、y向总位置差分别为(3.05±1.22、2.71±1.01),(2.05±0.55、1.8±0.5),(0.86±0.12、1.01±0.13),三者xy向都具有非常显著性差异(F=31.96,P＜0.001;F=26.991,P＜0.001);FI值分别为(0.549±0.203、0.742±0.12、0.898±0.09),三者具有非常显著性差异(F=23.03,P＜0.001);Dtotal分别为(11.23±3.58、6.52±2.55、3.57±0.79),三者具有非常显著性差异(F=31.96,P＜0.001).结论:1.三种配准方法中综合法的融合精度最高,能基本满足临床的需要.2.在完全解决一致性体位的前提下,用MI+外部标点法相结合的自动配准方法可避免人工干预,并且融合精度能完全满足临床的需要.