Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA.
Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung City, Taiwan.
Contrast Media Mol Imaging. 2017 Sep 17;2017:9730380. doi: 10.1155/2017/9730380. eCollection 2017.
The major problem with ventilation distribution calculations using DIR and 4DCT is the motion artifacts in 4DCT. Quite often not all phases would exhibit mushroom motion artifacts. If the ventilation series similarity is sufficiently robust, the ventilation distribution can be calculated using only the artifact-free phases. This study investigated the ventilation similarity among the data derived from different respiration phases. Fifteen lung cancer cases were analyzed. In each case, DIR was performed between the end-expiration phase and all other phases. Ventilation distributions were then calculated using the deformation matrices. The similarity was compared between the series ventilation distributions. The correlation between the majority phases was reasonably good, with average SCC values between 0.28 and 0.70 for the original data and 0.30 and 0.75 after smoothing. The better correlation between the neighboring phases, with average SCC values between 0.55 and 0.70 for the original data, revealed the nonlinear property of the dynamic ventilation. DSC analysis showed the same trend. To reduce the errors if motion artifacts are present, the phases without serious mushroom artifacts may be used. To minimize the effect of the nonlinearity in dynamic ventilation, the calculation phase should be chosen as close to the end-inspiration as possible.
使用 DIR 和 4DCT 进行通气分布计算的主要问题是 4DCT 中的运动伪影。通常情况下，并非所有相位都会出现蘑菇状运动伪影。如果通气系列的相似性足够强，则可以仅使用无伪影的相位来计算通气分布。本研究调查了来自不同呼吸相位的数据之间的通气相似性。分析了 15 例肺癌病例。在每种情况下，在呼气末期相与所有其他相位之间进行 DIR。然后使用变形矩阵计算通气分布。比较了系列通气分布之间的相似性。大多数相位之间的相关性相当好，原始数据的平均 SCC 值在 0.28 到 0.70 之间，平滑后为 0.30 到 0.75。原始数据中相邻相位之间的相关性更好，平均 SCC 值在 0.55 到 0.70 之间，这揭示了动态通气的非线性特性。DSC 分析显示出相同的趋势。为了减少存在运动伪影时的误差，可以使用没有严重蘑菇状伪影的相位。为了最小化动态通气中非线性的影响，计算相位应尽可能接近吸气末。
