Objective

Brain atrophy has the potential to become a biomarker for severity of radiation-induced side-effects. Particularly brain tumour patients can show great MRI signal changes over time caused by e.g. oedema, tumour progress or necrosis. The goal of this study was to investigate if such changes affect the segmentation accuracy of normal appearing brain and thus influence longitudinal volumetric measurements.

Materials and methods

T1-weighted MR images of 52 glioblastoma patients with unilateral tumours acquired before and three months after the end of radio(chemo)therapy were analysed. GM and WM volumes in the contralateral hemisphere were compared between segmenting the whole brain (full) and the contralateral hemisphere only (cl) with SPM and FSL. Relative GM and WM volumes were compared using paired t tests and correlated with the corresponding mean dose in GM and WM, respectively.

Results

Mean GM atrophy was significantly higher for full segmentation compared to cl segmentation when using SPM (mean ± std: ΔV_GM,full = − 3.1% ± 3.7%, ΔV_GM,cl = − 1.6% ± 2.7%; p < 0.001, d = 0.62). GM atrophy was significantly correlated with the mean GM dose with the SPM cl segmentation (r = − 0.4, p = 0.004), FSL full segmentation (r = − 0.4, p = 0.004) and FSL cl segmentation (r = -0.35, p = 0.012) but not with the SPM full segmentation (r = − 0.23, p = 0.1).

Conclusions

For accurate normal tissue volume measurements in brain tumour patients using SPM, abnormal tissue needs to be masked prior to segmentation, however, this is not necessary when using FSL.

中文翻译：

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高估放射（化学）治疗后胶质母细胞瘤患者的灰质萎缩

客观的

脑萎缩有可能成为辐射引起的副作用严重程度的生物标志物。特别是脑肿瘤患者可以显示出由例如水肿、肿瘤进展或坏死引起的随时间的巨大MRI信号变化。本研究的目的是调查这些变化是否会影响正常出现的大脑的分割精度，从而影响纵向体积测量。

材料和方法

分析了 52 例单侧肿瘤胶质母细胞瘤患者在放（化疗）治疗结束前和结束后 3 个月的 T1 加权 MR 图像。在用 SPM 和 FSL 分割整个大脑（完整）和仅对侧半球（cl）之间比较了对侧半球的 GM 和 WM 体积。使用配对 t 检验比较相对 GM 和 WM 体积，并分别与 GM 和 WM 中的相应平均剂量相关。

结果

与使用 SPM 时的 cl 分割相比，完全分割的平均 GM 萎缩显着更高（平均值±标准差：Δ V _GM，full  = - 3.1% ± 3.7%，Δ V _GM，cl  = - 1.6% ± 2.7%；p  < 0.001 , d  = 0.62)。GM 萎缩与 SPM cl 分割 ( r  = - 0.4, p  = 0.004)、FSL 完整分割 ( r  = - 0.4, p  = 0.004) 和 FSL cl 分割 (r = -0.35, p = 0.012）但不使用 SPM 完整分割（r  = - 0.23，p  = 0.1）。

结论

为了使用 SPM 在脑肿瘤患者中准确测量正常组织体积，需要在分割之前屏蔽异常组织，但是，在使用 FSL 时，这不是必需的。