PDF(Pubmed)
Abstract：
UNASSIGNED: Diffusion weighted imaging (DWI) allows for the interrogation of tissue cellularity, which is a surrogate for cellular proliferation. Previous attempts to incorporate DWI into the workflow of a 0.35 T MR-linac (MRL) have lacked quantitative accuracy. In this study, accuracy, repeatability, and geometric precision of apparent diffusion coefficient (ADC) maps produced using an echo planar imaging (EPI)-based DWI protocol on the MRL system is illustrated, and in vivo potential for longitudinal patient imaging is demonstrated.
UNASSIGNED: Accuracy and repeatability were assessed by measuring ADC values in a diffusion phantom at three timepoints and comparing to reference ADC values. System-dependent geometric distortion was quantified by measuring the distance between 93 pairs of phantom features on ADC maps acquired on a 0.35 T MRL and a 3.0 T diagnostic scanner and comparing to spatially precise CT images. Additionally, for five sarcoma patients receiving radiotherapy on the MRL, same-day in vivo ADC maps were acquired on both systems, one of which at multiple timepoints.
UNASSIGNED: Phantom ADC quantification was accurate on the 0.35 T MRL with significant discrepancies only seen at high ADC. Average geometric distortions were 0.35 (±0.02) mm and 0.85 (±0.02) mm in the central slice and 0.66 (±0.04) mm and 2.14 (±0.07) mm at 5.4 cm off-center for the MRL and diagnostic system, respectively. In the sarcoma patients, a mean pretreatment ADC of 910x10-6 (±100x10-6) mm2/s was measured on the MRL.
UNASSIGNED: The acquisition of accurate, repeatable, and geometrically precise ADC maps is possible at 0.35 T with an EPI approach.
UNASSIGNED: Accuracy and repeatability were assessed by measuring ADC values in a diffusion phantom at three timepoints and comparing to reference ADC values. System-dependent geometric distortion was quantified by measuring the distance between 93 pairs of phantom features on ADC maps acquired on a 0.35 T MRL and a 3.0 T diagnostic scanner and comparing to spatially precise CT images. Additionally, for five sarcoma patients receiving radiotherapy on the MRL, same-day in vivo ADC maps were acquired on both systems, one of which at multiple timepoints.
UNASSIGNED: Phantom ADC quantification was accurate on the 0.35 T MRL with significant discrepancies only seen at high ADC. Average geometric distortions were 0.35 (±0.02) mm and 0.85 (±0.02) mm in the central slice and 0.66 (±0.04) mm and 2.14 (±0.07) mm at 5.4 cm off-center for the MRL and diagnostic system, respectively. In the sarcoma patients, a mean pretreatment ADC of 910x10-6 (±100x10-6) mm2/s was measured on the MRL.
UNASSIGNED: The acquisition of accurate, repeatable, and geometrically precise ADC maps is possible at 0.35 T with an EPI approach.
摘要：
■扩散加权成像（DWI）允许询问组织细胞性，这是细胞增殖的替代品。先前尝试将DWI合并到0.35TMR直线加速器（MRL）的工作流程中的尝试缺乏定量准确性。在这项研究中,准确度,重复性,说明了在MRL系统上使用基于回波平面成像（EPI）的DWI协议产生的表观扩散系数（ADC）图的几何精度，并证明了患者纵向成像的体内潜力。
■通过在三个时间点测量扩散体模中的ADC值并与参考ADC值进行比较来评估准确性和可重复性。通过在0.35TMRL和3.0T诊断扫描仪上获取的ADC图上测量93对体模特征之间的距离，并与空间精确的CT图像进行比较，可以量化与系统相关的几何失真。此外,对于接受MRL放疗的五名肉瘤患者，在两个系统上都获得了同一天的体内ADC图，其中一个在多个时间点。
■PhantomADC定量在0.35TMRL上是准确的，仅在高ADC下观察到显着差异。对于MRL和诊断系统，中心切片的平均几何变形为0.35（±0.02）mm和0.85（±0.02）mm，在偏离中心5.4cm处的平均几何变形为0.66（±0.04）mm和2.14（±0.07）mm。分别。在肉瘤患者中，在MRL上测得平均预处理ADC为910x10-6(±100x10-6)mm2/s。
■获取精确，可重复,和几何精确的ADC图是可能的0.35T与EPI方法。
■通过在三个时间点测量扩散体模中的ADC值并与参考ADC值进行比较来评估准确性和可重复性。通过在0.35TMRL和3.0T诊断扫描仪上获取的ADC图上测量93对体模特征之间的距离，并与空间精确的CT图像进行比较，可以量化与系统相关的几何失真。此外,对于接受MRL放疗的五名肉瘤患者，在两个系统上都获得了同一天的体内ADC图，其中一个在多个时间点。
■PhantomADC定量在0.35TMRL上是准确的，仅在高ADC下观察到显着差异。对于MRL和诊断系统，中心切片的平均几何变形为0.35（±0.02）mm和0.85（±0.02）mm，在偏离中心5.4cm处的平均几何变形为0.66（±0.04）mm和2.14（±0.07）mm。分别。在肉瘤患者中，在MRL上测得平均预处理ADC为910x10-6(±100x10-6)mm2/s。
■获取精确，可重复,和几何精确的ADC图是可能的0.35T与EPI方法。
