INTRODUCTION There is growing evidence that the subventricular zone (SVZ) plays a key role in glioblastoma (GBM) tumorigenesis. However, little is known regarding how the SVZ, which is a harbor for adult neural stem cells, may be influenced by chemoradiation. The current diffusion-weighted imaging (DWI) study explored ipsilateral and contralateral alterations in the anterior SVZ in GBM patients with posterior enhancing lesions following chemoradiation. METHODS Forty GBM patients with tumor involvement in the posterior SVZ (mean age = 57 ± 10; left-hemisphere N = 25; right-hemisphere N = 15) were evaluated using DWI before and after chemoradiation. Regions-of-interest were drawn on the ipsilesional and contralesional anterior SVZ on apparent diffusion coefficient (ADC) maps for both timepoints. ADC histogram analysis was performed by modeling a bimodal, double Gaussian distribution to obtain ADCL, defined as the mean of the lower Gaussian distribution. RESULTS The ipsilesional SVZ had lower ADCL values compared to the contralesional SVZ before treatment (mean difference = 0.025 μm2/ms; P = 0.007). Following chemoradiation, these changes were no longer observed (mean difference = 0.0025 μm2/ms; P > 0.5), as ADCL values of the ipsilesional SVZ increased (mean difference = 0.026 μm2/ms; P = 0.037). An increase in ipsilesional ADCL was associated with shorter progression-free (P = 0.0119) and overall survival (P = 0.0265). CONCLUSIONS These preliminary observations suggest baseline asymmetry as well as asymmetric changes in the SVZ proximal (ipsilesional) to the tumor with respect to contralesional SVZ regions may be present in GBM, potentially implicating this region in tumorigenesis and/or treatment resistance.

中文翻译：

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胶质母细胞瘤伴有后脑室的化学放疗后，前脑室下区的弥散MRI变化。

引言越来越多的证据表明脑室下区（SVZ）在胶质母细胞瘤（GBM）的肿瘤发生中起关键作用。但是，关于成年神经干细胞的港口SVZ如何受化学辐射影响的了解甚少。当前的弥散加权成像（DWI）研究探索了在放化疗后具有后增强病变的GBM患者中，前SVZ的同侧和对侧改变。方法对40例GBM肿瘤累及后方SVZ的患者（平均年龄= 57±10；左半球N = 25；右半球N = 15）在放化疗前后进行DWI评估。在两个时间点的视扩散系数（ADC）图上，在同侧和对侧前SVZ上绘制了感兴趣的区域。ADC直方图分析是通过对双峰双高斯分布进行建模以获得ADCL（定义为较低高斯分布的平均值）来进行的。结果与治疗前的对侧SVZ相比，同侧SVZ的ADCL值较低（平均差异= 0.025μm2/ ms； P = 0.007）。化学放疗后，随着同侧SVZ的ADCL值增加（平均差异= 0.026μm2/ ms； P = 0.037），不再观察到这些变化（平均差异= 0.0025μm2/ ms； P> 0.5）。同侧ADCL的增加与较短的无进展（P = 0.0119）和总生存期（P = 0.0265）相关。结论这些初步观察结果表明，GBM中可能存在基线不对称以及与对侧SVZ区相关的SVZ肿瘤近端（同侧）的不对称变化，