Background: Distinguishing tumor recurrence from radiation necrosis after radiotherapy for brain metastases remains a major diagnostic challenge. Perfusion MRI, particularly the measurement of relative cerebral blood volume (rCBV), is a commonly used technique to differentiate between these two entities. However, variations in the placement of regions of interest (ROIs) affect diagnostic accuracy. This study compares the diagnostic performance of different cerebral perfusion methods, including a novel volumetric 3D ROI method and automatic thresholding, to differentiate tumor recurrence from radiation necrosis.Methods: We retrospectively analyzed data from 23 patients, including 25 brain metastases treated with stereotactic radiotherapy, who were suspected of local recurrence and had histological confirmation via biopsy or surgical resection. Each patient underwent perfusion MRI before surgery. The diagnostic performance of the different ROI methods (manual and 3D) was evaluated using the area under the ROC curve (AUC), as well as sensitivity and specificity measures. An automatic thresholding method was also applied, generating tumor sub-volumes with predefined cut-off values to determine the rCBV threshold most specific for differentiating relapse from necrosis.Results: The 3D ROI method, considering the whole lesion and a healthy ROI in the head of the caudate nucleus, demonstrated superior diagnostic performance (AUC = 0.65), outperforming manual methods (AUC = 0.53). Robustness was moderate, with an intraclass correlation coefficient of 0.60 between Syngo.via and IntelliSpace.Conclusions: The 3D ROI method shows promise in improving diagnostic accuracy in distinguishing tumor recurrence from radiation necrosis. Further studies with standardized protocols and larger populations are needed to validate these results.
背景：脑转移瘤放疗后鉴别肿瘤复发与放射性坏死仍是重大诊断挑战。灌注磁共振成像，特别是相对脑血容量（rCBV）测量，是区分这两种病变的常用技术。然而，感兴趣区（ROI）的放置差异会影响诊断准确性。本研究比较了不同脑灌注方法的诊断效能，包括新型三维容积ROI法和自动阈值法，以区分肿瘤复发与放射性坏死。 方法：我们回顾性分析了23例患者的资料，包括25个经立体定向放疗的脑转移瘤，这些病例疑似局部复发并通过活检或手术切除获得组织学证实。每位患者术前均接受灌注磁共振成像。通过受试者工作特征曲线下面积（AUC）、敏感性和特异性指标评估不同ROI方法（手动与三维法）的诊断效能。同时应用自动阈值法，通过预设截断值生成肿瘤亚体积，以确定最能特异性区分复发与坏死的rCBV阈值。 结果：采用三维ROI方法（考虑整个病灶及尾状核头部的健康ROI）展现出更优的诊断效能（AUC=0.65），优于手动方法（AUC=0.53）。该方法稳健性中等，Syngo.via与IntelliSpace系统间的组内相关系数为0.60。 结论：三维ROI方法在提高鉴别肿瘤复发与放射性坏死的诊断准确性方面具有潜力。需要通过标准化方案和更大样本量的研究进一步验证这些结果。
肿瘤(癌症)患者之家