Redefining the target early during treatment. Can we visualize regional differences within the target volume using sequential diffusion weighted MRI?
Redefining the target early during treatment. Can we visualize regional differences within the target volume using sequential diffusion weighted MRI?
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DOI：
10.1016/j.radonc.2013.09.023
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发表时间：
2014-02-01
影响因子：
5.7
通讯作者：
Nuyts, Sandra
中科院分区：
文献类型：
--
作者：
Lambrecht, Maarten;Van Herck, Hans;Nuyts, Sandra
目的：对于头颈癌，弥散加权 MRI (DWI) 可以在治疗期间早期预测反应。治疗引起的变化和 DWI 特异性伪影阻碍了表观扩散系数 (ADC) 图之间的准确配准。该研究的目的是开发一种配准工具，计算并可视化 ADC 的区域变化。方法：20 名接受初级放疗的 IV 期 HNC 患者在治疗前和治疗早期接受了 MRI 包括 DWI。在两个时间点，将标记手动放置在不同模式的解剖标志处。开发了一种配准方法，该方法由全自动刚性和非刚性配准以及两个半自动薄板样条（TPS）扭曲组成，并将其应用于图像集。在每个配准步骤之后，计算平均配准误差，并比较良好响应者和差响应者之间的 Delta ADC。结果：添加 TPS 扭曲显着降低了配准误差（以毫米为单位，6.3 +/- 6.2 与 3.2 +/- 3.3 毫米，p < 0.001）。基于标记的配准后，反应不佳者的 Delta ADC 中位数显着低于反应良好者（7% 对比 21%；p < 0.001）。结论：这种配准方法可以显着降低平均配准误差。此外，在放疗早期对 Delta ADC 进行体素计算，可以可视化肿瘤内 Delta ADC 的区域差异。 (C) 2013 Elsevier Ireland Ltd. 保留所有权利。
Purpose: In head and neck cancer, diffusion weighted MRI (DWI) can predict response early during treatment. Treatment-induced changes and DWI-specific artifacts hinder an accurate registration between apparent diffusion coefficient (ADC) maps. The aim of the study was to develop a registration tool which calculates and visualizes regional changes in ADC..Methods: Twenty patients with stage IV HNC treated with primary radiotherapy received an MRI including DWI before and early during treatment. Markers were manually placed at anatomical landmarks on the different modalities at both time points. A registration method, consisting of a fully automatic rigid and nonrigid registration and two semi-automatic thin-plate spline (TPS) warps was developed and applied to the image sets. After each registration step the mean registration errors were calculated and Delta ADC was compared between good and poor responders.Results: Adding the TPS warps significantly reduced the registration error (in mm, 6.3 +/- 6.2 vs 3.2 +/- 3.3 mm, p < 0.001). After the marker based registration the median Delta ADC in poor responders was significantly lower than in good responders (7% vs. 21%; p < 0.001).Conclusions: This registration method allowed for a significant reduction of the mean registration error. Furthermore the.voxel-wise calculation of the Delta ADC early during radiotherapy allowed for a visualization of the regional differences of Delta ADC within the tumor. (C) 2013 Elsevier Ireland Ltd. All rights reserved.