Lee Junkyo, Lee Min Woo, Choi Dongil, Cha Dong Ik, Lee Sunyoung, Kang Tae Wook, Yang Jehoon, Jo Jaemoon, Bang Won-Chul, Kim Jongsik, Shin Dongkuk
Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Korea.
Medical Imaging R&D Group, SAMSUNG MEDISON Co., Ltd., Seoul, Korea.
Ultrasonography. 2018 Oct;37(4):337-344. doi: 10.14366/usg.17065. Epub 2017 Dec 21.
The purpose of this study was to evaluate the accuracy of an active contour model for estimating the posterior ablative margin in images obtained by the fusion of real-time ultrasonography (US) and 3-dimensional (3D) US or magnetic resonance (MR) images of an experimental tumor model for radiofrequency ablation.
Chickpeas (n=12) and bovine rump meat (n=12) were used as an experimental tumor model. Grayscale 3D US and T1-weighted MR images were pre-acquired for use as reference datasets. US and MR/3D US fusion was performed for one group (n=4), and US and 3D US fusion only (n=8) was performed for the other group. Half of the models in each group were completely ablated, while the other half were incompletely ablated. Hyperechoic ablation areas were extracted using an active contour model from real-time US images, and the posterior margin of the ablation zone was estimated from the anterior margin. After the experiments, the ablated pieces of bovine rump meat were cut along the electrode path and the cut planes were photographed. The US images with the estimated posterior margin were compared with the photographs and post-ablation MR images. The extracted contours of the ablation zones from 12 US fusion videos and post-ablation MR images were also matched.
In the four models fused under real-time US with MR/3D US, compression from the transducer and the insertion of an electrode resulted in misregistration between the real-time US and MR images, making the estimation of the ablation zones less accurate than was achieved through fusion between real-time US and 3D US. Eight of the 12 post-ablation 3D US images were graded as good when compared with the sectioned specimens, and 10 of the 12 were graded as good in a comparison with nicotinamide adenine dinucleotide staining and histopathologic results.
Estimating the posterior ablative margin using an active contour model is a feasible way of predicting the ablation area, and US/3D US fusion was more accurate than US/MR fusion.
本研究旨在评估一种活动轮廓模型在通过实时超声（US）与实验性肿瘤模型的三维（3D）US或磁共振（MR）图像融合所获得的图像中估计射频消融后消融边缘的准确性。
使用鹰嘴豆（n = 12）和牛臀肉（n = 12）作为实验性肿瘤模型。预先采集灰度3D US和T1加权MR图像用作参考数据集。一组（n = 4）进行US与MR/3D US融合，另一组（n = 8）仅进行US与3D US融合。每组中一半的模型进行完全消融，另一半进行不完全消融。使用活动轮廓模型从实时US图像中提取高回声消融区域，并从前缘估计消融区的后缘。实验后，沿着电极路径切割牛臀肉的消融块，并拍摄切割平面的照片。将估计有后缘的US图像与照片以及消融后MR图像进行比较。还对12个US融合视频和消融后MR图像中提取的消融区轮廓进行匹配。
在实时US与MR/3D US融合的四个模型中，换能器的压迫和电极的插入导致实时US与MR图像之间配准不良，使得消融区的估计不如实时US与3D US融合准确。与切片标本相比，12张消融后3D US图像中有8张评级为良好，与烟酰胺腺嘌呤二核苷酸染色和组织病理学结果相比，12张中有10张评级为良好。
使用活动轮廓模型估计后消融边缘是预测消融区域的一种可行方法，并且US/3D US融合比US/MR融合更准确。
