Reproducibility of registration-based measures of lung tissue expansion
Reproducibility of registration-based measures of lung tissue expansion
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DOI：
10.1118/1.3685589
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发表时间：
2012-03-01
期刊：
影响因子：
3.8
通讯作者：
Reinhardt, Joseph M.
中科院分区：
文献类型：
--
作者：
Du, Kaifang;Bayouth, John E.;Reinhardt, Joseph M.
目的：肺功能取决于肺在呼吸周期中的扩张和收缩。呼吸门控CT成像和3D图像配准可用于通过计算图像配准变形场的雅可比矩阵的行列式来局部估计肺组织扩张和收缩（局部肺体积变化）。在这项研究中，作者研究了重复4DCT收购机械通气羊和自由呼吸human.Methods：4DCT图像数据从三个白色羊和9个人类受试者的肺组织扩张的雅可比性为基础的措施的再现性。在每种情况下，在短时间间隔内为每个受试者采集两个4DCT研究。动物受试者被麻醉和机械通气，而人类是清醒的，并根据呼吸起搏音频提示自主呼吸。从每个4DCT数据集中，选择由近端吸气重建的体积和近端呼气重建的体积组成的图像对。使用组织体积保持变形配准算法配准吸气末和呼气末图像，并且使用配准变形场的雅可比矩阵来测量局部肺扩张。通过测量逐个体素的雅可比比，将基线数据集的雅可比图与随访数据的雅可比图进行比较。结果：在动物受试者中，平均雅可比比（基线扫描雅可比除以随访扫描雅可比，逐个体素）为0.99846 +/- 0.021（平均值+/-标准差，整个肺部区域的平均值）。人类受试者的平均雅可比比为1.02246 +/- 0.058。雅可比值的再现性被认为是强烈依赖于受试者的呼吸努力和呼吸pattern.Conclusions的再现性：肺扩张，肺功能的替代品，可以评估使用两个或更多的门控CT图像采集。结果表明，在麻醉的机械通气动物中可以获得良好的再现性，但呼吸努力和呼吸模式的变化降低了自主呼吸人类的再现性。全局线性归一化可以全局补偿呼吸努力差异，但是均匀缩放不考虑区域肺扩张速率的差异。需要进行额外的工作来开发补偿程序或标准化方案，以解释呼吸期间肺扩张的局部变化。(C)2012年美国医学物理学家协会。[DOI：10.1118/1.3685589]
Purpose: Lung function depends on lung expansion and contraction during the respiratory cycle. Respiratory-gated CT imaging and 3D image registration can be used to locally estimate lung tissue expansion and contraction (regional lung volume change) by computing the determinant of the Jacobian matrix of the image registration deformation field. In this study, the authors examine the reproducibility of Jacobian-based measures of lung tissue expansion in two repeat 4DCT acquisitions of mechanically ventilated sheep and free-breathing humans.Methods: 4DCT image data from three white sheep and nine human subjects were used for this analysis. In each case, two 4DCT studies were acquired for each subject within a short time interval. The animal subjects were anesthetized and mechanically ventilated, while the humans were awake and spontaneously breathing based on respiratory pacing audio cues. From each 4DCT data set, an image pair consisting of a volume reconstructed near end inspiration and a volume reconstructed near end exhalation was selected. The end inspiration and end exhalation images were registered using a tissue volume preserving deformable registration algorithm and the Jacobian of the registration deformation field was used to measure regional lung expansion. The Jacobian map from the baseline data set was compared to the Jacobian map from the followup data by measuring the voxel-by-voxel Jacobian ratio.Results: In the animal subjects, the mean Jacobian ratio (baseline scan Jacobian divided by followup scan Jacobian, voxel-by-voxel) was 0.99846 +/- 0.021 (mean +/- standard deviation, averaged over the entire lung region). The mean Jacobian ratio was 1.02246 +/- 0.058 in the human subjects. The reproducibility of the Jacobian values was found to be strongly dependent on the reproducibility of the subject's respiratory effort and breathing pattern.Conclusions: Lung expansion, a surrogate for lung function, can be assessed using two or more respiratory-gated CT image acquisitions. The results show that good reproducibility can be obtained in anesthetized, mechanically ventilated animals, but variations in respiratory effort and breathing patterns reduce reproducibility in spontaneously-breathing humans. The global linear normalization can globally compensate for breathing effort differences, but a homogeneous scaling does not account for differences in regional lung expansion rates. Additional work is needed to develop compensation procedures or normalization schemes that can account for local variations in lung expansion during respiration. (C) 2012 American Association of Physicists in Medicine. [DOI: 10.1118/1.3685589]