Department of Radiotherapy, Erasmus MC Cancer Institute, University Medical Center, Rotterdam, The Netherlands.
Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
MAGMA. 2022 Feb;35(1):127-143. doi: 10.1007/s10334-021-00997-y. Epub 2022 Feb 7.
As microscopic tumour infiltration of glioblastomas is not visible on conventional magnetic resonance (MR) imaging, an isotropic expansion of 1-2 cm around the visible tumour is applied to define the clinical target volume for radiotherapy. An opportunity to visualize microscopic infiltration arises with advanced MR imaging. In this review, various advanced MR biomarkers are explored that could improve target volume delineation for radiotherapy of glioblastomas. Various physiological processes in glioblastomas can be visualized with different advanced MR techniques. Combining maps of oxygen metabolism (CMRO), relative cerebral blood volume (rCBV), vessel size imaging (VSI), and apparent diffusion coefficient (ADC) or amide proton transfer (APT) can provide early information on tumour infiltration and high-risk regions of future recurrence. Oxygen consumption is increased 6 months prior to tumour progression being visible on conventional MR imaging. However, presence of the Warburg effect, marking a switch from an infiltrative to a proliferative phenotype, could result in CMRO to appear unaltered in high-risk regions. Including information on biomarkers representing angiogenesis (rCBV and VSI) and hypercellularity (ADC) or protein concentration (APT) can omit misinterpretation due to the Warburg effect. Future research should evaluate these biomarkers in radiotherapy planning to explore the potential of advanced MR techniques to personalize target volume delineation with the aim to improve local tumour control and/or reduce radiation-induced toxicity.
由于常规磁共振成像（MR）无法显示胶质母细胞瘤的微观肿瘤浸润，因此在可见肿瘤周围应用 1-2cm 的各向同性扩展来定义放射治疗的临床靶区。先进的 MR 成像为可视化微观浸润提供了机会。在这篇综述中，探讨了各种先进的 MR 生物标志物，这些标志物可以改善胶质母细胞瘤放射治疗的靶区勾画。不同的先进 MR 技术可以可视化胶质母细胞瘤中的各种生理过程。氧代谢图（CMRO）、相对脑血容量（rCBV）、血管大小成像（VSI）以及表观扩散系数（ADC）或酰胺质子转移（APT）的组合图可以提供肿瘤浸润和未来复发高风险区域的早期信息。在常规 MR 成像可见肿瘤进展之前 6 个月，氧消耗增加。然而，由于沃伯格效应的存在，标志着从浸润性到增殖性表型的转变，CMRO 在高风险区域可能表现为不变。包括代表血管生成（rCBV 和 VSI）和细胞增多（ADC）或蛋白质浓度（APT）的生物标志物信息可以避免由于沃伯格效应导致的错误解释。未来的研究应在放射治疗计划中评估这些生物标志物，以探索先进的 MR 技术在个体化靶区勾画方面的潜力，旨在提高局部肿瘤控制率和/或降低放射性毒性。
