MR-PWI在鼻咽癌放疗靶区勾画中的应用价值

目的：探讨磁共振灌注成像对鼻咽癌放疗靶区勾画和剂量学的影响。方法：收集20例初治的鼻咽癌患者，分别行CT、MR、MR-PWI扫描定位，然后分别勾画靶区得到原发灶大体肿瘤靶区和淋巴结转移灶靶区的绝对体积及相关危及器官的平均剂量和最大剂量，进行对比分析。结果：CT组勾画的GTV-t体积较MR组、MR-PWI组大，差异有统计学意义（P＜0.05），ＭＲ组较CT组勾画的GTV-n体积小，两组对比差异有统计学意义（P＜0.05）。脑干所受最大剂量在MR-PWI组和CT组比较差异有统计学意义（P＜0.05），但平均剂量在不同组间的差异均无统计学意义（P＜0.05）。结论：MR勾画靶区在确定靶区边界上较CT更精确，MR-PWI作为辅助显像方法，可作为靶区勾画的参考。

Application Value of MR-PWI in Target Volume Delineation in Radiotherapy for Nasopharyngeal Carcinoma

Objective:To investigate and discuss the influence of magnetic resonance perfusion weighted imaging(MR-PWI)on target volume delineation and dosimetry in radiotherapy for nasopharyngeal carcinoma(NPC).Methods:We collected 20 NPC patients.Images of computed tomography(CT),magnetic resonance(MR),and MR-PWI were taken.Then we obtained the absolute gross tumor volumeprimary tumor(GTV-t),metastatic lymphadenopathy(GTV-n)],and mean dose and maximum dose of organs at risk for statistical analysis.Results:Volume of GTV-t in the CT group was larger than those in MR and MR-PWI group.The difference was statistically significant(P<0.05).Volume of GTV-n in the MR group was smaller than that in the CT group,and the difference between the two groups was statistically significant(P<0.05).Maximum brainstem dose was significantly different between the MR-PWI group and the CT group(P<0.05).Mean brainstem dose was not significantly different among different groups(P>0.05).Conclusion:MR is more accurate than CT for target volume delineation in determining boundary of target area.MR-PWI as an auxiliary imaging method can be used as a reference for target delineation.