Zukauskaite Ruta, Brink Carsten, Hansen Christian Rønn, Bertelsen Anders, Johansen Jørgen, Grau Cai, Eriksen Jesper Grau
Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
Department of Oncology, Odense University Hospital, Sdr. Boulevard 29, C 5000, Odense, Denmark.
Strahlenther Onkol. 2016 Aug;192(8):545-51. doi: 10.1007/s00066-016-0998-4. Epub 2016 Jun 20.
Clinical application of deformable registration (DIR) of medical images remains limited due to sparse validation of DIR methods in specific situations, e. g. in case of cancer recurrences. In this study the accuracy of DIR for registration of planning CT (pCT) and recurrence CT (rCT) images of head and neck squamous cell carcinoma (HNSCC) patients was evaluated.
Twenty patients treated with definitive IMRT for HNSCC in 2010-2012 were included. For each patient, a pCT and an rCT scan were used. Median interval between the scans was 8.5 months. One observer manually contoured eight anatomical regions-of-interest (ROI) twice on pCT and once on rCT.
pCT and rCT images were deformably registered using the open source software elastix. Mean surface distance (MSD) and Dice similarity coefficient (DSC) between contours were used for validation of DIR. A measure for delineation uncertainty was estimated by assessing MSD from the re-delineations of the same ROI on pCT. DIR and manual contouring uncertainties were correlated with tissue volume and rigidity.
MSD varied 1-3 mm for different ROIs for DIR and 1-1.5 mm for re-delineated ROIs performed on pCT. DSC for DIR varied between 0.58 and 0.79 for soft tissues and was 0.79 or higher for bony structures, and correlated with the volumes of ROIs (r = 0.5, p < 0.001) and tissue rigidity (r = 0.54, p < 0.001).
DIR using elastix in HNSCC on planning and recurrence CT scans is feasible; an uncertainty of the method is close to the voxel size length of the planning CT images.
由于在特定情况下，如癌症复发时，可变形图像配准（DIR）方法的验证较少，医学图像的可变形配准在临床中的应用仍然有限。在本研究中，评估了DIR对头颈部鳞状细胞癌（HNSCC）患者的计划CT（pCT）和复发CT（rCT）图像进行配准的准确性。
纳入了2010年至2012年期间接受确定性调强放疗（IMRT）治疗的20例HNSCC患者。对于每位患者，使用了一次pCT扫描和一次rCT扫描。两次扫描之间的中位间隔时间为8.5个月。一名观察者在pCT上手动勾勒出八个解剖感兴趣区域（ROI）两次，在rCT上手动勾勒一次。
使用开源软件elastix对pCT和rCT图像进行可变形配准。轮廓之间的平均表面距离（MSD）和骰子相似系数（DSC）用于验证DIR。通过评估pCT上相同ROI重新勾勒的MSD来估计轮廓不确定性的度量。DIR和手动勾勒的不确定性与组织体积和硬度相关。
对于DIR，不同ROI的MSD在1至3毫米之间变化，在pCT上重新勾勒的ROI的MSD在1至1.5毫米之间变化。DIR的DSC对于软组织在0.58至0.79之间变化，对于骨结构为0.79或更高，并且与ROI的体积（r = 0.5，p < 0.001）和组织硬度（r = 0.54，p < 0.001）相关。
在HNSCC的计划和复发CT扫描中使用elastix进行DIR是可行的；该方法的不确定性接近计划CT图像的体素大小长度。
