Shusharina Nadya, Maier Stephan E, Lam Miranda B, Kaza Evangelia
Division of Radiation Biophysics, Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts.
Harvard Medical School, Boston, Massachusetts.
Adv Radiat Oncol. 2024 Oct 28;10(1):101661. doi: 10.1016/j.adro.2024.101661. eCollection 2025 Jan.
Defining a microscopic tumor infiltration boundary is critical to the success of radiation therapy. Currently, radiation oncologists use margins to geometrically expand the visible tumor for radiation treatment planning in soft tissue sarcomas (STS). Image-based models of tumor progression would be critical to personalize the treatment radiation field to the pattern of sarcoma spread. Evaluation of these models is necessary to demonstrate feasibility in the clinical setting. This study presents an imaging protocol for the preclinical evaluation of a tumor progression model in extremity STS.
We recruited 7 healthy volunteers and acquired diffusion-weighted magnetic resonance imaging (DW-MRI) images of the thigh on a magnetic resonance imaging scanner used for imaging cancer patients in a radiation oncology department. We developed a protocol that includes positioning the patient, configuring the radiofrequency coils, and setting the DW-MRI sequence parameters. To find the optimal parameter configuration, the image signal-to-noise ratio (SNR) and the directional variability (DV) of the principal eigenvector of the diffusion tensor were calculated.
The mean SNR across all trials and 12 thigh muscles was 41, with a range of 12 to 72. The mean DV was 13° and ranged from 11° to 23°. The longest scan time was 22 minutes and 58 seconds, and the shortest was 11 minutes and 46 seconds. For the high-resolution image with a voxel volume of 1.3 × 1.3 × 6 mm and 38 slices, the optimal parameters were found to be a repetition time of 8000 ms, 12 signal averages, and 6 gradient directions. This configuration resulted in a scan time of 11 minutes and 46 seconds, an SNR of 34, and a DV of 13°.
A DW-MRI scan duration acceptable for imaging cancer patients was achieved with an image quality suitable for reproducible modeling of tumor infiltration. The developed protocol can be used for preclinical evaluation in STS patients.
确定微观肿瘤浸润边界对于放射治疗的成功至关重要。目前，放射肿瘤学家在软组织肉瘤（STS）的放射治疗计划中使用边界来几何扩展可见肿瘤。基于图像的肿瘤进展模型对于根据肉瘤扩散模式个性化治疗放射野至关重要。评估这些模型对于证明其在临床环境中的可行性是必要的。本研究提出了一种用于肢体STS中肿瘤进展模型临床前评估的成像方案。
我们招募了7名健康志愿者，并在放射肿瘤学部门用于癌症患者成像的磁共振成像扫描仪上获取了大腿的扩散加权磁共振成像（DW-MRI）图像。我们制定了一个方案，包括患者定位、配置射频线圈和设置DW-MRI序列参数。为了找到最佳参数配置，计算了图像信噪比（SNR）和扩散张量主特征向量的方向变异性（DV）。
所有试验和12块大腿肌肉的平均SNR为41，范围为12至72。平均DV为13°，范围为11°至23°。最长扫描时间为22分58秒，最短为11分46秒。对于体素体积为1.3×1.3×6 mm且有38层的高分辨率图像，发现最佳参数为重复时间8000 ms、12次信号平均和6个梯度方向。这种配置导致扫描时间为11分46秒，SNR为34，DV为13°。
实现了对癌症患者成像可接受的DW-MRI扫描持续时间，且图像质量适合肿瘤浸润的可重复建模。所制定的方案可用于STS患者的临床前评估。
