Neurosciences & Mental Health Research Program, Research Institute, The Hospital for Sick Children, Toronto, Canada.
Institute of Medical Science, University of Toronto, Toronto, Canada.
Eur Radiol. 2024 Apr;34(4):2772-2781. doi: 10.1007/s00330-023-10267-1. Epub 2023 Oct 7.
OBJECTIVES: Currently, the BRAF status of pediatric low-grade glioma (pLGG) patients is determined through a biopsy. We established a nomogram to predict BRAF status non-invasively using clinical and radiomic factors. Additionally, we assessed an advanced thresholding method to provide only high-confidence predictions for the molecular subtype. Finally, we tested whether radiomic features provide additional predictive information for this classification task, beyond that which is embedded in the location of the tumor. METHODS: Random forest (RF) models were trained on radiomic and clinical features both separately and together, to evaluate the utility of each feature set. Instead of using the traditional single threshold technique to convert the model outputs to class predictions, we implemented a double threshold mechanism that accounted for uncertainty. Additionally, a linear model was trained and depicted graphically as a nomogram. RESULTS: The combined RF (AUC: 0.925) outperformed the RFs trained on radiomic (AUC: 0.863) or clinical (AUC: 0.889) features alone. The linear model had a comparable AUC (0.916), despite its lower complexity. Traditional thresholding produced an accuracy of 84.5%, while the double threshold approach yielded 92.2% accuracy on the 80.7% of patients with the highest confidence predictions. CONCLUSION: Models that included radiomic features outperformed, underscoring their importance for the prediction of BRAF status. A linear model performed similarly to RF but with the added benefit that it can be visualized as a nomogram, improving the explainability of the model. The double threshold technique was able to identify uncertain predictions, enhancing the clinical utility of the model. CLINICAL RELEVANCE STATEMENT: Radiomic features and tumor location are both predictive of BRAF status in pLGG patients. We show that they contain complementary information and depict the optimal model as a nomogram, which can be used as a non-invasive alternative to biopsy. KEY POINTS: • Radiomic features provide additional predictive information for the determination of the molecular subtype of pediatric low-grade gliomas patients, beyond what is embedded in the location of the tumor, which has an established relationship with genetic status. • An advanced thresholding method can help to distinguish cases where machine learning models have a high chance of being (in)correct, improving the utility of these models. • A simple linear model performs similarly to a more powerful random forest model at classifying the molecular subtype of pediatric low-grade gliomas but has the added benefit that it can be converted into a nomogram, which may facilitate clinical implementation by improving the explainability of the model.
目的:目前,儿科低级别胶质瘤(pLGG)患者的 BRAF 状态是通过活检确定的。我们建立了一个列线图,通过临床和放射组学因素无创预测 BRAF 状态。此外,我们评估了一种先进的阈值方法,为分子亚型提供仅具有高置信度的预测。最后,我们测试了放射组学特征是否为该分类任务提供了超越肿瘤位置所嵌入的信息的附加预测信息。
方法:随机森林(RF)模型分别基于放射组学和临床特征进行训练,以评估每个特征集的效用。我们没有使用传统的单阈值技术将模型输出转换为类别预测,而是实现了一种考虑不确定性的双阈值机制。此外,还训练了一个线性模型并以列线图的形式进行了描述。
结果:联合 RF(AUC:0.925)优于仅基于放射组学(AUC:0.863)或临床(AUC:0.889)特征训练的 RF。尽管线性模型的复杂性较低,但它的 AUC 相似(0.916)。传统阈值产生了 84.5%的准确率,而双阈值方法在具有最高置信度预测的 80.7%的患者中产生了 92.2%的准确率。
结论:包含放射组学特征的模型表现优于不包含放射组学特征的模型,这突出了它们对 BRAF 状态预测的重要性。线性模型的性能与 RF 相似,但具有可以可视化的优势作为列线图,从而提高了模型的可解释性。双阈值技术能够识别不确定的预测,增强了模型的临床实用性。
临床相关性声明:放射组学特征和肿瘤位置均可预测 pLGG 患者的 BRAF 状态。我们表明,它们包含互补信息,并将最佳模型描绘为列线图,可以作为活检的非侵入性替代方法。
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