Mao Weihua, Kim Joshua, Chetty Indrin J
Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, United States.
Front Oncol. 2022 Jun 30;12:868076. doi: 10.3389/fonc.2022.868076. eCollection 2022.
PURPOSES/OBJECTIVES: Historically, motion correlation between internal tumor and external surrogates have been based on limited sets of X-ray or magnetic resonance (MR) images. With the recent clinical implementation of MR-guided linear accelerators, a vast quantity of continuous planar real-time MR imaging data is acquired. In this study, information was extracted from MR cine imaging during liver cancer treatments to establish associations between internal tumor/diaphragm and external surface/skin movement.
This retrospective study used 305,644 MR image frames acquired over 118 treatment/imaging sessions of the first 23 liver cancer patients treated on an MRI-linac. 9 features were automatically determined on each MR image frame: Lung_Area, the posterior (Dia_Post), dome (Dia_Dome), and anterior (Dia_Ant) points of a diaphragmatic curve and the diaphragm curve point (Dia_Max), the chest (Chest) and the belly (Belly) skin points experiencing the maximum motion ranges; the superior-interior (SI) and posterior-anterior (PA) positions of a target. For every session, correlation analyses were performed twice among the 9 features: 1) over a breath-hold (BH) set and 2) on a pseudo free-breathing (PFB) generated by removing breath-holding frames.
303,123 frames of images were successfully analyzed. For BH set analysis, correlation coefficients were as follows: 0.94 ± 0.07 between any two features among Dia_Post, Dia_Dome, Dia_Max, and Lung_Area; 0.95 ± 0.06 between SI and any feature among Dia_Post, Dia_Dome, Dia_Max, or Lung_Area; 0.76 ± 0.29 between SI and Belly (with 50% of correlations ≥ 0.87). The PFB set had 142,862 frames of images. For this set, correlation coefficients were 0.96 ± 0.06 between any two features among Dia_Post, Dia_Dome, Dia_Max, and Lung_Area; 0.95 ± 0.06 between SI and any feature among Dia_Post, Dia_Dome, Dia_Max, or Lung_Area; 0.80 ± 0.26 between SI and Belly (with 50% of correlations ≥ 0.91).
Diaphragmatic motion as assessed by cine MR imaging is highly correlated with liver tumor motion. Belly vertical motion is highly correlated with liver tumor longitudinal motion in approximately half of the cases. More detailed analyses of those cases displaying weak correlations are in progress.
目的/目标：从历史上看，内部肿瘤与外部替代物之间的运动相关性一直基于有限的X射线或磁共振（MR）图像集。随着MR引导直线加速器在临床中的最新应用，获取了大量连续的平面实时MR成像数据。在本研究中，从肝癌治疗期间的MR电影成像中提取信息，以建立内部肿瘤/膈肌与外部表面/皮肤运动之间的关联。
这项回顾性研究使用了在一台MRI直线加速器上接受治疗的前23例肝癌患者的118次治疗/成像过程中获取的305,644帧MR图像。在每个MR图像帧上自动确定9个特征：肺面积、膈肌曲线的后点（Dia_Post）、穹顶点（Dia_Dome）和前点（Dia_Ant）以及膈肌曲线点（Dia_Max）、胸部（Chest）和腹部（Belly）皮肤点，这些点经历最大运动范围；靶区的上内（SI）和后前（PA）位置。对于每个疗程，在这9个特征之间进行两次相关性分析：1）在屏气（BH）组上；2）在通过去除屏气帧生成的伪自由呼吸（PFB）上。
成功分析了303,123帧图像。对于BH组分析，相关系数如下：Dia_Post、Dia_Dome、Dia_Max和肺面积中任意两个特征之间为0.94±0.07；SI与Dia_Post、Dia_Dome、Dia_Max或肺面积中的任何特征之间为0.95±0.06；SI与腹部之间为0.76±0.29（50%的相关性≥0.87）。PFB组有142,862帧图像。对于该组，相关系数如下：Dia_Post、Dia_Dome、Dia_Max和肺面积中任意两个特征之间为0.96±0.06；SI与Dia_Post、Dia_Dome、Dia_Max或肺面积中的任何特征之间为0.95±0.06；SI与腹部之间为0.80±0.26（50%的相关性≥0.91）。
通过电影MR成像评估的膈肌运动与肝肿瘤运动高度相关。在大约一半的病例中，腹部垂直运动与肝肿瘤纵向运动高度相关。正在对那些显示弱相关性的病例进行更详细的分析。
