Department of Radiology (EB44), Medical Imaging Centre (MIC), University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
Department of Nuclear Medicine and Molecular Imaging, Medical Imaging Centre (MIC), University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
Br J Radiol. 2021 Sep 1;94(1125):20210275. doi: 10.1259/bjr.20210275. Epub 2021 Aug 18.
Radiation-induced changes (RIC) secondary to focal radiotherapy can imitate tumour progression in brain metastases and make follow-up clinical decision making unreliable. C-methyl-L-methionine-PET (MET-PET) is widely used for the diagnosis of RIC in brain metastases, but minimal literature exists regarding the optimum PET measuring parameter to be used. We analysed the diagnostic performance of different MET-PET measuring parameters in distinguishing between RIC and tumour progression in a retrospective cohort of brain metastasis patients.
26 patients with 31 metastatic lesions were included on the basis of having undergone a PET scan due to radiological uncertainty of disease progression. The PET images were analysed and methionine uptake quantified using standardised-uptake-values (SUV) and tumour-to-normal tissue (T/N) ratios, generated as SUV, SUV, SUV, T/N, T/N and T/N. Metabolic-tumour-volume and total-lesion methionine metabolism were also computed. A definitive diagnosis of either RIC or tumour progression was established by clinicoradiological follow-up of least 4 months subsequent to the investigative PET scan.
All MET-PET parameters except metabolic-tumour-volume showed statistically significant differences between tumour progression and lesions with RIC. Receiver-operating-characteristic curve and area-under the-curve analysis demonstrated the highest value of 0.834 for SUV with a corresponding optimum threshold of 3.29. This associated with sensitivity, specificity, positive predictive and negative predictive values of 78.57, 70.59%, 74.32 and 75.25% respectively.
MET-PET is a useful modality for the diagnosis of RIC in brain metastases. SUV was the PET parameter with the greatest diagnostic performance.
More robust comparisons between SUV and SUV could enhance follow-up treatment planning.
由于局灶放射治疗引起的放射性变化（RIC）可能模仿脑转移瘤的肿瘤进展，从而使随访的临床决策变得不可靠。C-甲基-L-蛋氨酸-PET（MET-PET）广泛用于脑转移瘤的 RIC 诊断，但关于要使用的最佳 PET 测量参数的文献很少。我们分析了不同 MET-PET 测量参数在区分脑转移瘤患者的 RIC 和肿瘤进展方面的诊断性能。
根据放射学疾病进展的不确定性，对 26 例 31 个转移性病变的患者进行了 PET 扫描。对 PET 图像进行分析，并使用标准化摄取值（SUV）和肿瘤与正常组织（T/N）比值（SUV、SUV、SUV、T/N、T/N 和 T/N）量化蛋氨酸摄取。还计算了代谢肿瘤体积和总病变蛋氨酸代谢。通过对调查性 PET 扫描后至少 4 个月的临床放射学随访，确定是 RIC 还是肿瘤进展的明确诊断。
除代谢肿瘤体积外，所有 MET-PET 参数在肿瘤进展和具有 RIC 的病变之间均有统计学差异。受试者工作特征曲线和曲线下面积分析显示，SUV 的值最高为 0.834，对应的最佳阈值为 3.29。这与 78.57%、70.59%、74.32%和 75.25%的敏感性、特异性、阳性预测值和阴性预测值相关。
MET-PET 是诊断脑转移瘤 RIC 的有用方法。SUV 是具有最大诊断性能的 PET 参数。
更深入地比较 SUV 和 SUV 可以增强随访治疗计划。
