Department of Radiation Oncology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; Institute of Radiation Medicine (IRM), Helmholtz Zentrum München, Neuherberg, Germany; Deutsches Konsortium für Translationale Krebsforschung (DKTK), DKTK Partner Site, Munich, Germany.
Department of Radiation Oncology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; Department of Neurosurgery, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
Radiother Oncol. 2022 Jun;171:189-197. doi: 10.1016/j.radonc.2022.04.012. Epub 2022 Apr 18.
Management of high-grade gliomas (HGGs) close to motor areas is challenging due to the risk of treatment-related morbidity. Thus, for resection, functional mapping of the corticospinal tract (CST) with navigated transcranial magnetic stimulation (nTMS) combined with diffusion tensor imaging (DTI)-based fiber tracking (DTI-FT) is increasingly used. This study investigated the application of DTI-FT in adjuvant radiation therapy (RT) planning of HGGs for CST avoidance.
The preoperative DTI-FT-based CST reconstructions of 35 patients harboring HGGs were incorporated into the RT planning system and merged with planning imaging. The CST was delineated as the planning risk volume (PRV-FT). Intensity-modulated RT (IMRT) plans were optimized to preserve PRV-FT. Segments within the planning target volume (PTV) were not spared (overlap).
With plan optimization, mean dose (Dmean) of PRV-FT can be reduced by 17.1% on average (range 0.1-37.9%), thus from 25.5 Gy to 21.2 Gy (p < 0.001). For PRV-FT segments beyond the PTV dose, reduction is possible by 26.8% (range 0.1-43.9%, Dmean 17.4 Gy vs. 12.5 Gy, p < 0.001). Considering only portions within the 50% isodose level, Dmean is decreased by 46.7% from 38.6 Gy to 20.5 Gy (range 19.1-62.8%, p < 0.001). PTV coverage was not affected: V95% and V90% were 96.4 ± 3.1% and 98.0 ± 3.9% vs. 96.1 ± 3.5% (p = 0.34) and 98.3 ± 2.9% (p = 0.58). Dose constraints for organs at risk (OARs) were all met.
This study demonstrates that DTI-FT can be utilized in the RT planning of HGGs for CST sparing. However, the degree of dose reduction depends on the overlap with the PTV. The functional benefit needs to be investigated in future prospective clinical trials.
由于治疗相关发病率的风险，靠近运动区的高级别神经胶质瘤（HGG）的管理具有挑战性。因此，对于切除术，越来越多地使用经颅磁刺激（nTMS）与基于扩散张量成像（DTI）的纤维跟踪（DTI-FT）相结合来进行皮质脊髓束（CST）的功能定位。本研究探讨了 DTI-FT 在 HGG 辅助放射治疗（RT）计划中避免 CST 的应用。
对 35 例 HGG 患者进行术前 DTI-FT 基于 CST 的重建，并将其纳入 RT 计划系统并与计划成像融合。CST 被描绘为计划风险体积（PRV-FT）。优化强度调制 RT（IMRT）计划以保留 PRV-FT。计划靶区（PTV）内的段不被保留（重叠）。
通过计划优化，PRV-FT 的平均剂量（Dmean）平均可降低 17.1%（范围为 0.1-37.9%），从 25.5Gy 降至 21.2Gy（p<0.001）。对于超过 PTV 剂量的 PRV-FT 段，可以降低 26.8%（范围为 0.1-43.9%，Dmean 为 17.4Gy 与 12.5Gy，p<0.001）。考虑仅在 50%等剂量线内的部分，Dmean 从 38.6Gy 降低至 20.5Gy，降低了 46.7%（范围为 19.1-62.8%，p<0.001）。PTV 覆盖不受影响：V95%和 V90%分别为 96.4±3.1%和 98.0±3.9%与 96.1±3.5%（p=0.34）和 98.3±2.9%（p=0.58）。危及器官（OARs）的剂量限制均得到满足。
本研究表明，DTI-FT 可用于 HGG 的 RT 计划以避免 CST 损伤。然而，剂量降低的程度取决于与 PTV 的重叠程度。需要在未来的前瞻性临床试验中研究功能获益。
