Lawrence Liam S P, Chan Rachel W, Chen Hanbo, Stewart James, Ruschin Mark, Theriault Aimee, Myrehaug Sten, Detsky Jay, Maralani Pejman J, Tseng Chia-Lin, Soliman Hany, Jane Lim-Fat Mary, Das Sunit, Stanisz Greg J, Sahgal Arjun, Lau Angus Z
Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.
Radiother Oncol. 2023 Nov;188:109873. doi: 10.1016/j.radonc.2023.109873. Epub 2023 Aug 26.
Survival in glioblastoma might be extended by escalating the radiotherapy dose to treatment-resistant tumour and adapting to tumour changes. Diffusion-weighted imaging (DWI) on MRI-linear accelerators (MR-Linacs) could be used to identify a dose escalation target, but its prognostic value must be demonstrated. The purpose of this study was to determine whether MR-Linac DWI can assess treatment response in glioblastoma and whether changes in DWI show greater prognostic value than changes in the contrast-enhancing gross tumour volume (GTV).
Seventy-five patients with glioblastoma were treated with chemoradiotherapy, of which 32 were treated on a 1.5 T MRI-linear accelerator (MR-Linac). Patients were imaged with simulation MRI scanners (MR-sim) at treatment planning and weeks 2, 4, and 10 after treatment start. Twenty-eight patients had additional MR-Linac DWI sequences. Cox modelling was used to evaluate the correlation of overall and progression-free survival (OS and PFS) with clinical variables and volumetric changes in the GTV and low-ADC regions (ADC < 1.25 µm/ms within GTV).
In total, 479 MR-Linac DWI and 289 MR-sim DWI datasets were analyzed. MR-Linac low-ADC changes between weeks 2 and 5 inclusive were prognostic for OS (hazard ratio lower limits ≥ 1.2, p-values ≤ 0.02). MR-sim low-ADC changes showed greater correlation with OS and PFS than GTV changes (e.g., OS hazard ratio at week 2 was 3.4 (p <0.001) for low-ADC versus 2.0 (p = 0.022) for GTV).
MR-Linac DWI can measure low-ADC tumour volumes that correlate with OS and PFS better than contrast-enhancing GTV. Low-ADC regions could serve as dose escalation targets.
通过提高对治疗抵抗性肿瘤的放疗剂量并适应肿瘤变化，胶质母细胞瘤患者的生存期可能得以延长。磁共振直线加速器（MR-Linac）上的扩散加权成像（DWI）可用于识别剂量递增靶点，但其预后价值必须得到证实。本研究的目的是确定MR-Linac DWI能否评估胶质母细胞瘤的治疗反应，以及DWI的变化是否比增强扫描的大体肿瘤体积（GTV）变化具有更大的预后价值。
75例胶质母细胞瘤患者接受了放化疗，其中32例在1.5T磁共振直线加速器（MR-Linac）上接受治疗。患者在治疗计划时以及治疗开始后第2、4和10周使用模拟磁共振成像扫描仪（MR-sim）进行成像。28例患者有额外的MR-Linac DWI序列。采用Cox模型评估总生存期和无进展生存期（OS和PFS）与临床变量以及GTV和低表观扩散系数（ADC）区域（GTV内ADC<1.25µm/ms）体积变化的相关性。
共分析了479个MR-Linac DWI数据集和289个MR-sim DWI数据集。在第2周和第5周（含）之间MR-Linac低ADC变化对OS具有预后意义（风险比下限≥1.2，p值≤0.02）。MR-sim低ADC变化与OS和PFS的相关性高于GTV变化（例如，第2周时低ADC的OS风险比为3.4（p<0.001），而GTV为2.0（p=0.022））。
MR-Linac DWI能够测量与OS和PFS相关性优于增强扫描GTV的低ADC肿瘤体积。低ADC区域可作为剂量递增靶点。
