BACKGROUND Malignant transformation represents the natural evolution of diffuse low-grade gliomas (LGG). This is a catastrophic event, causing neurocognitive symptoms, intensified treatment and premature death. However, little is known concerning the spatial distribution of malignant transformation in patients with LGG. MATERIALS AND METHODS Patients histopathological diagnosed with LGG and subsequent radiological malignant transformation were identified from two different institutions. We evaluated the spatial distribution of malignant transformation with (1) visual inspection and (2) segmentations of longitudinal tumor volumes. In (1) a radiological transformation site < 2 cm from the tumor on preceding MRI was defined local transformation. In (2) overlap with pretreatment volume after importation into a common space was defined as local transformation. With a centroid model we explored if there were particular patterns of transformations within relevant subgroups. RESULTS We included 43 patients in the clinical evaluation, and 36 patients had MRIs scans available for longitudinal segmentations. Prior to malignant transformation, residual radiological tumor volumes were > 10 ml in 93% of patients. The transformation site was considered local in 91% of patients by clinical assessment. Patients treated with radiotherapy prior to transformation had somewhat lower rate of local transformations (83%). Based upon the segmentations, the transformation was local in 92%. We did not observe any particular pattern of transformations in examined molecular subgroups. CONCLUSION Malignant transformation occurs locally and within the T2w hyperintensities in most patients. Although LGG is an infiltrating disease, this data conceptually strengthens the role of loco-regional treatments in patients with LGG.

中文翻译：

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低度神经胶质瘤患者恶性转化的空间分布。

背景技术恶性转化代表弥散性低级神经胶质瘤（LGG）的自然进化。这是一个灾难性事件，导致神经认知症状，强化治疗和过早死亡。然而，关于LGG患者恶性转化的空间分布知之甚少。材料与方法从两个不同的机构中鉴定出经组织病理学诊断为LGG并随后发生放射学恶性转化的患者。我们通过（1）目视检查和（2）纵向肿瘤体积分割来评估恶性转化的空间分布。在（1）中，在先前MRI上距肿瘤<2 cm的放射学转换位点被定义为局部转换。在（2）中，与导入到公共空间中的预处理体积的重叠被定义为局部变换。使用质心模型，我们探索了相关子组中是否存在特定的转换模式。结果我们在临床评估中纳入了43例患者，其中36例接受了MRI扫描以进行纵向分割。在进行恶性转化之前，93％的患者中残留的放射肿瘤体积> 10 ml。根据临床评估，该转化位点在91％的患者中被认为是局部的。转化前接受放射治疗的患者局部转化率较低（83％）。基于细分，转换率为92％。我们在观察的分子亚组中没有观察到任何特殊的转化模式。结论大多数患者在T2w高信号的局部和内部发生恶性转化。尽管LGG是一种浸润性疾病，但该数据从概念上增强了LGG患者局部治疗的作用。