Purpose

BRAF V600E mutation is a distinctive genomic alteration of pediatric low-grade gliomas with prognostic and therapeutic implications. The aim of this retrospective multicenter study was to analyze imaging features of BRAF V600E-mutant and wild-type cerebral pilocytic astrocytomas (PAs) and gangliogliomas (GGs), focusing on the role of diffusion weighted imaging (DWI).

Methods

We retrospectively evaluated 56 pediatric patients with histologically proven, treatment-naïve PAs and GGs who underwent conventional MRI, DWI, and molecular analysis for BRAF V600E mutation. Twenty-three subjects presented BRAF V600E-mutant (12 PAs and 11 GGs) and 33 BRAF V600E wild-type (26 PAs and 7 GGs) tumors. Imaging studies were reviewed for dominant site, margin definition, hemorrhage, calcification, cystic components, contrast enhancement, and relative mean and minimum ADC values (rADCmean and rADCmin). Statistics included Fisher’s exact test, Student t test, general linear model, and receiver operating characteristic (ROC) analysis.

Results

PA and GG BRAF V600E-mutant had significantly lower rADCmean (p < 0.001) and rADCmin (p < 0.001) values than wild type, regardless of tumor histology and location. ROC analysis demonstrated similar performances between these parameters in predicting BRAF V600E status (rADCmean: AUC 0.831, p < 0.001; rADCmin: AUC 0.885, p < 0.001).

No significant differences regarding additional imaging features emerged between BRAF V600E-mutant and wild-type lesions, with the exception of the number of tumors with cystic components, significantly higher in BRAF V600E-mutant PAs (p = 0.011)

Conclusion

Assessment of the DWI characteristics of GGs and PAs may assist in predicting BRAF V600E status, suggesting a radiogenomic correlation and prompt molecular characterization of these tumors.

目的

BRAF V600E突变是小儿低度神经胶质瘤的独特基因组改变，具有预后和治疗意义。这项回顾性多中心研究的目的是分析BRAF V600E突变型和野生型脑毛细血管星形细胞瘤（PAs）和神经节胶质瘤（GGs）的影像学特征，重点是弥散加权成像（DWI）的作用。

方法

我们回顾性评估了56名经组织学证实，未接受过治疗的PA和GG的儿科患者，这些患者接受了常规MRI，DWI和BRAF V600E突变的分子分析。23名受试者出现了BRAF V600E突变（12个PA和11个GG）和33个BRAF V600E野生型（26个PA和7个GG）肿瘤。回顾了影像学研究的主要部位，边缘定义，出血，钙化，囊性成分，造影剂增强以及相对平均和最小ADC值（rADCmean和rADCmin）。统计数据包括Fisher的精确检验，Student t检验，通用线性模型和接收器工作特性（ROC）分析。

结果

PA和GG BRAF V600E突变体的rADCmean（p <0.001）和rADCmin（p <0.001）值均明显低于野生型，而与肿瘤的组织学和位置无关。ROC分析表明，在预测BRAF V600E状态时，这些参数之间具有相似的性能（rADCmean：AUC 0.831，p <0.001； rADCmin：AUC 0.885，p <0.001）。

在BRAF V600E突变型和野生型病变之间，在其他影像学特征方面无显着差异，除了具有囊性成分的肿瘤数量外，在BRAF V600E突变型PA中明显更高（p = 0.011）

结论

评估GGs和PAs的DWI特征可能有助于预测BRAF V600E的状态，提示这些肿瘤的放射基因组相关性和及时的分子特征。