Safety Margin Assessment After Radiofrequency Ablation of the Liver Using Registration of Preprocedure and Postprocedure CT Images
Safety Margin Assessment After Radiofrequency Ablation of the Liver Using Registration of Preprocedure and Postprocedure CT Images
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DOI：
10.2214/ajr.10.5122
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发表时间：
2011-05-01
影响因子：
5
通讯作者：
Choi, Byung Ihn
中科院分区：
文献类型：
--
作者：
Kim, Kyung Won;Lee, Jeong Min;Choi, Byung Ihn
目标。本研究的目的是评价一种新的术前CT图像配准技术，以确定其对射频消融(RFA)后安全边界评估的影响。在31例接受RFA治疗的肝细胞癌患者中，使用原型软件通过非刚性配准将RFA后的CT图像与RFA前的CT图像进行配准。通过在RFA后和RFA前CT图像上设置相应的标志点对，并计算相应标志点之间的平均差值来验证配准的准确性。三位放射科医生独立地对RFA前和RFA后的CT图像进行了回顾性回顾，以评估有无注册图像的安全边界。安全边际采用4分制(1，残留肿瘤；2，2 mm安全边际；3，2至5 mm安全边际；4，=5 mm安全边际)。观察者间的一致性采用加权kappa检验进行评估。结果对应的地标之间的平均差异为1.3 mm，因此建议准确配准。使用配准CT图像的阅读器安全裕度的程度与参考值之间的相关性比不使用配准图像时更准确(阅读器1的伽马系数分别为0.918和0.887，阅读器2的伽马系数为0.888和0.651，阅读器3的伽马系数为0.811和0.497)。观察者间的一致性(Kappa)从第一次未注册图像的0.503-0.558增加到第二次有注册CT图像的0.807-0.869。结论：RFA后CT图像与RFA前CT图像的配准是一种准确且有用的技术，可用于评估RFA术后的安全范围。
OBJECTIVE. The purpose of our study was to evaluate a new technique for registration of postprocedure to preprocedure CT images to determine the effect on the safety margin assessment after radiofrequency ablation (RFA).MATERIALS AND METHODS. Registration of post-RFA CT to pre-RFA CT images was performed using prototype software via nonrigid registration in 31 patients with hepatocellular carcinoma who were treated with RFA. Registration accuracy was validated by setting pairs of corresponding landmarks on registered post-RFA CT and pre-RFA CT images and by calculating the mean difference between the corresponding landmarks. Three radiologists independently conducted a retrospective review of the pre-RFA and post-RFA CT images for safety margin assessment with and without registered images. The safety margin was rated using a 4-point scale (1, residual tumor; 2, < 2 mm safety margin; 3, 2 to < 5 mm safety margin; and 4, >= 5 mm safety margin). Interobserver agreement was evaluated using the weighted kappa test.RESULTS. The mean difference between the corresponding landmarks was 1.3 mm, thus suggesting accurate registration. A more accurate correlation between the degree of the reader safety margin and the reference value was obtained from pre-RFA and post-RFA CT images using registered CT images than without using registered images (gamma, 0.918 vs 0.887 for reader 1, 0.888 vs 0.651 for reader 2, and 0.811 vs 0.497 for reader 3, respectively). Interobserver agreement (kappa) increased from 0.503-0.558 in the first session without registered images to 0.807-0.869 in the second session with registered CT images.CONCLUSION. Registration of post-RFA CT to pre-RFA CT images is an accurate and useful technique for assessing the safety margin immediately after RFA.