对比T2WI与T2^(*)WI用于前列腺癌放射治疗计划的效果

Comparison on T2WI and T2^(*)WI for radiotherapy planning of prostate cancer

目的对比观察T2WI与T2^(*)WI在基于黄金基准标志物(GFM)放射治疗(简称放疗)前列腺癌(PCa)中融合CT-MR图像和勾画靶区的效果。方法针对线性测试假体(LTB)采集T2WI与T2^(*)WI,评估图像质量。将3枚GFM置入凝胶中,采集CT、T2WI及T2^(*)WI,评价T2WI与T2^(*)WI的匹配度。对10例经病理确诊的PCa患者行经直肠超声引导下细针抽吸术,将3枚GFM置入前列腺靶区不同层面后采集盆腔CT、T2WI及T2^(*)WI。分别由3名放疗医师(RTP)于各种图像上勾画PCa靶区,以软件自动测量两两之间于各种图像内的放疗等中心处同层面勾画靶区的豪斯多夫距离、戴斯相似系数(DSC)和Cohen's Kappa系数,并计算其平均值,评价3种图像的形变匹配度。结果针对LTB,T2^(*)WI存在轻微几何失真,T2WI与T2^(*)WI三维重建图像中LTB中心的空间位移为0.11 mm。T2WI与T2^(*)WI识别凝胶中的GFM的准确率均为100%(6/6)。T2WI三维重建图像中,GFM中心相对CT三维重建的空间位移平均值为0.26 mm;T2^(*)WI重建图像则为0.20 mm。临床试验结果显示,基于T2WI识别GFM的准确率为10.00%(3/30),基于T2^(*)WI则为96.67%(29/30)。3名RTP基于CT、T2WI与T2^(*)WI勾画靶区的豪斯多夫距离、DSC、Cohen's Kappa系数平均值差异均有统计学意义(F=12.365、3.398、4.109,P均<0.001),两两比较差异均有统计学意义(P均<0.05)。结论制定PCa放疗计划时,相比T2WI,T2^(*)WI更适用于融合CT-MR图像和勾画靶区。

Objective To compare T2WI and T2^(*)WI in CT-MR image fusion and target delineation of prostate cancer(PCa)in radiotherapy based on gold fiducial marker(GFM).Methods T2WI and T2^(*)WI of linearity test object(LTB)were acquired,and the imaging qualities were evaluated.Three GFM were implanted into gel,and then CT,T2WI and T2^(*)WI were collected for evaluating the image matching degree of T2WI and T2^(*)WI.Trans-rectal ultrasound-guided fine needle aspiration was performed in 10 patients with PCa confirmed with pathology,and 3 GFM were implanted into different layers of the prostate target area in each patient.Pelvic CT,T2WI and T2^(*)WI were collected.PCa targets were outlined by 3 radiotherapy physicians(RTP)on different images,respectively,and the Hausdorff distance,dais similarity coefficient(DSC)and Cohen's Kappa coefficient of the target areas were automatically measured by software were compared between each pairs based on the same level of radiotherapy isocrocenter on different images,and the average value of the above parameters were calculated to evaluate the matching degree of the three kinds of image deformation.Results For LTB,slight geometric distortion occurred on T2^(*)WI,and the spatial displacement of LTB center between T2WI and T2^(*)WI 3D reconstruction images was 0.11 mm.The accurate recognition rate of GFM in gel on T2WI and T2^(*)WI was both 100%(6/6).Relative to CT 3D reconstruction image,the mean spatial displacement of GFM center on 3D reconstruction T2WI was 0.26 mm,while that on T2^(*)WI was 0.20 mm.Clinical trials showed that the accurate recognition rate of GFM on T2WI was 10.00%(3/30),on T2^(*)WI was 96.67%(29/30).The mean Hausdorff distance,DSC and Cohen's Kappa coefficient of the target areas delineated by 3 RTP on CT,T2WI and T2^(*)WI were all significant different(F=12.365,3.398,4.109,all P<0.001),while pairwise comparison also showed significant differences(all P<0.05).Conclusion For radiotherapy planning of PCa,T2^(*)WI was more suitable for GFM based CT-MR image fusion and PCa target delineation than T2WI.