The quantitative study of brain white matter variation after radiotherapy by MR imaging radiomics

Objective: To study the MR radiomics features variation of brain white matter before and after radiotherapy for brain tumors, and analyze the relationship between radiomics features and radiation dose, to provide a reference method for early prediction and monitoring of radiation-induced brain white matter injury. Methods: A total of 70 patients with brain tumors who received radiotherapy in Shandong Cancer Hospital and Institute from September 2018 to July 2020 were selected in this study. CT and MR simulation images (T1-enhanced, T1-enhanced and T1-enhanced to T1-enhanced silhouette images) were obtained respectively, and MR images were obtained again after 23 ∼ 50 Gy radiotherapy. According to the actual dose of the patient, the white matter in different dose gradients of 0 ∼ 5 Gy, 5 ∼ 10 Gy, 10 ∼ 15 Gy, 15 ∼ 20 Gy, 20 ∼ 30 Gy, 30 ∼ 40 Gy and > 40 Gy was defined as region of interest (ROI). The influence radiomics features of different ROI in T1 plain scan, T1 enhanced and T1 silhouette images were extracted, and the differences of each ROI MR image radiomics l features before and after radiotherapy were compared, and the relationship between radiomics features variation and radiation dose changes was analyzed. Results: 93 radiomics features were extracted from each set of images for each ROI. For T1 plain scan, T1 enhanced and T1 silhouette images, the number of features with statistically significant differences between before and after radiotherapy: 0 ∼ 5 Gy: 52, 52, 7, 5 ∼ 10 Gy: 1, 1, 9, 10 ∼ 15 Gy: 0, 16, 28, 15 ∼ 20 Gy: 15, 8, 2, 20 ∼ 30 Gy: 1, 77, 25, 30 ∼ 40 Gy: 38, 64, 29, > 40 Gy: 32, 47, For the characteristics with variation rate more than ± 50% before and after radiotherapy, in the dose gradients of 0 ∼ 5 Gy, 5 ∼ 10 Gy, 10 ∼ 15 Gy, 15 ∼ 20 Gy, 20 ∼ 30 Gy, 30 ∼ 40 Gy and > 40 Gy, the maximum change rates of imaging characteristics of different MR sequences were as follows: T1 plain scan 164.06%, 1.39%, N/A, 35.76%, 7.4%, 156.45%, 657.25%, respectively. T1 enhanced 126.88%, 2.7%, 198.7%, 192.92%, 128%, 149.19%, 531.96% T1 silhouette -605.04%, -656.93%, 739.06%, -325.36%, 1919.53%, 4967.44%, 6081.3%, and for T1 silhouette the radiomics features variation was significantly higher than T1 plain scan and T1 enhancement. Conclusion: The MR radiomics features of the brain white matter changed significantly under different dose gradients before and after radiotherapy, which could reveal the microscopic changes of white matter than conventional gross images method, and could provide a feasible objective method for early prediction and detection of radiation damage of brain white matter. (authors)