SU-F-303-10: Impact of Visual Biofeedback On Respiratory Reproducibility in 4DMRI
SU-F-303-10: Impact of Visual Biofeedback On Respiratory Reproducibility in 4DMRI
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SU-F-303-10：视觉生物反馈对 4DMRI 呼吸再现性的影响
DOI：
10.1118/1.4925237
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发表时间：
2015
期刊：
影响因子：
3.8
通讯作者：
C. Glide
中科院分区：
文献类型：
--
作者：
D. To;J. Kim;R. Price;I. Chetty;C. Glide
目的：精确放射治疗腹部病变并发呼吸运动和4DCT软组织造影剂不理想。4DMRI提供了更好的对比度。然而，长时间的扫描和不规则的呼吸模式可能会限制。为了解决这个问题，我们在4DMRI中引入了视觉生物反馈（VBF）。方法：8名健康志愿者同意接受irb批准的方案。在开放的1.0T MR- SIM上获得前瞻性呼吸触发，t2加权冠状4dmri。VBF采用核磁共振兼容的交互式屏气控制系统进行集成。受试者在视觉上监测他们的呼吸模式，以保持在预先确定的容忍范围内。在有和没有VBF的情况下获得4dmri，进行2-8期采集。评估归一化呼吸波形的扫描时间、占空比（编程/采集时间）、呼吸周期、吸气末（EI）振幅和呼吸变异性（变异系数，EI- cov）。基于b样条的可变形图像配准将轮廓从呼气末（EE）传播到呼气末（EI）阶段。通过质心分析计算呼吸引起的肝脏运动并进行比较。结果：结合VBF可缩短两相采集时间（带VBF和不带VBF分别为4.7±0.6和5.6±1.4分钟），降低EI-COV振幅53.0±8.1%。平均而言，结合VBF可将8期4DMRI采集时间缩短1.7±1.2分钟，将ei - cov采集时间缩短46.0±15.8%。使用VBF比自由呼吸产生更高的占空比（分别为34.7%和28.3%）。在呼吸频率保持相似的情况下，VBF组的4DMRI采集时间缩短（有BPM的10.5±4.0 vs没有BPM的10.6±3.3）。与无VBF组相比，有VBF组呼吸波形的EI振幅（0.84±0.05 a.u）高于无VBF组（0.72±0.06 a.u）。这转化为肝脏偏移的差异，其中上-下，前后和左右EE-EI位移分别为14.3±3.6,4.8±2.1和1.6±1.0 mm，与无VBF相比，13.0±6.2,3.8±2.4和1.2±1.4 mm。结论：将VBF系统应用于4DMRI可显著减少采集时间和呼吸变异性。虽然VBF降低了肝脏运动的可变性，但观察到偏移的差异，这表明在整个RT工作流程中需要实施。研究部分由Philips HealthCare （Best, Netherlands）资助，并与MedSpira签订了设备评估协议。
Purpose: Precise radiation therapy (RT) for abdominal lesions is complicated by respiratory motion and suboptimal soft tissue contrast in 4DCT. 4DMRI offers improved contrast. However, long scan times and irregular breathing patterns can be limiting. To address this, we introduced visual biofeedback (VBF) into 4DMRI. Methods: Eight healthy volunteers were consented to an IRB-approved protocol. Prospective respiratory-triggered, T2-weighted coronal 4DMRIs were acquired on an open 1.0T MR- SIM. VBF was integrated using an MR-compatible interactive breath-hold control system. Subjects visually monitored their breathing patterns to stay within pre-determined tolerances. 4DMRIs were acquired with and without VBF for 2–8 phase acquisitions. Normalized respiratory waveforms were evaluated for scan time, duty cycle (programmed/acquisition time), breathing period, end-inhale (EI) amplitude, and breathing variability (coefficient of variation, EI-COV). B-spline-based deformable image registration propagated contours from end-exhale (EE) to EI phases. Respiration-induced liver motion was calculated via centroid analysis and compared. Results: Incorporating VBF reduced 2-phase acquisition time (4.7±0.6 and 5.6±1.4 minutes with and without VBF, respectively) while reducing the amplitude EI-COV by 53.0±8.1%. On average, incorporating VBF reduced 8-phase 4DMRI acquisition times by 1.7±1.2 minutes and EI-COVs by 46.0±15.8%. Using VBF yielded higher duty cycles than free breathing (34.7% versus 28.3%, respectively). 4DMRI acquisition time was reduced for the cohort with VBF despite breathing rate remaining similar (10.5±4.0 with vs. 10.6±3.3 BPM without). Respiratory waveforms showed higher EI amplitude with VBF (0.84±0.05 a.u.) as compared to 0.72±0.06 a.u. without. This translated to differences in liver excursions, where superior-inferior, anterior-posterior, and left-right EE-EI displacements were 14.3±3.6, 4.8±2.1, and 1.6±1.0 mm, respectively, with VBF compared to 13.0±6.2, 3.8±2.4, and 1.2±1.4 mm without. Conclusion: Incorporating VBF system into 4DMRI substantially reduced acquisition time and breathing variability. While VBF reduced liver motion variability, differences in excursion were observed, suggesting that implementation will be required throughout the RT workflow. Research supported in part by a grant from Philips HealthCare (Best, Netherlands) and an equipment evaluation agreement with MedSpira.