Department of Neurosurgery, Institute of Neuro Sciences, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
Department of Molecular Imaging and Nuclear Medicine, Indraprastha Apollo Hospitals, Sarita Vihar, New Delhi, India.
Neurol India. 2017 Mar-Apr;65(2):293-301. doi: 10.4103/neuroindia.NI_101_16.
To assess the utility of 18F-fluoroethyl-L-tyrosine (FET) positron emission tomography/magnetic resonance imaging (PET/MRI) in distinguishing recurrence from radionecrosis.
Thirty-two patients (25 males, 7 females) of glioma who had already undergone surgery/chemoradiotherapy and had enhancing brain lesions suspicious of recurrence were evaluated using integrated 18F-FET PET/MRI, and followed up with histopathology or clinical follow-up and/or MRI/PET/MRI imaging. Manually drawn regions of interest over areas of maximal enhancement or FET uptake were used to calculate tumor to background ratios [TBRmax, TBRmean], choline: creatine ratio [Cho: Cr ratio], normalized relative cerebral blood volume [N rCBVmean] and apparent diffusion coefficient [ADCmean]. Correlations were evaluated using Pearson's coefficient. Accuracy of each parameter was calculated using independent t-test and receiver operator curve (ROC) analysis while utility of all four parameters together using multivariate analysis of variance (MANOVA) for differentiating recurrence vs. radionecrosis was evaluated. Positive histopathology and imaging/clinical follow up served as the gold standard.
Twenty-four of the 32 patients were diagnosed with recurrent disease and 8 with radiation necrosis. Significant correlations were observed between TBRmaxand N rCBVmean (ρ =0.503; P = 0.003), TBRmean, and N rCBVmean (ρ =0.414; P = 0.018), TBRmaxand ADCmean (ρ = -0.52; P = 0.002), and TBRmeanand ADCmean(ρ = -0.518; P = 0.002). TBRmax, TBRmean, ADCmean, Cho: Cr ratios, and N rCBVmeanwere significant in differentiating recurrence from radiation necrosis with an accuracy of 94.1%, 88.2%, 80.4%, 96.4%, and 89.9%, respectively. MANOVA indicated that combination of all parameters demonstrated better evaluation of recurrence vs. necrosis than any single parameter. The diagnostic accuracy, sensitivity, and specificity using all MRI parameters were 93.75%, 96%, and 85.7%, and using all FET PET/MRI parameters was 96.87%, 100%, and 85.7%, respectively.
Synergetic effect of multiple MR parameters evaluated together in addition to FET PET uptake highlights the fact that integrated 18F-FET PET/MRI might have the potential to impact management of patients with glioma by timely and conclusive recognition of true recurrence from radiation necrosis.
评估 18F-氟乙基-L-酪氨酸（FET）正电子发射断层扫描/磁共振成像（PET/MRI）在区分复发与放射性坏死中的作用。
对 32 例已接受手术/放化疗且存在增强脑病变疑似复发的胶质瘤患者进行了整合 18F-FET PET/MRI 检查，并通过组织病理学或临床随访和/或 MRI/PET/MRI 成像进行随访。通过手动在最大强化区域或 FET 摄取区域绘制感兴趣区，计算肿瘤与背景比[TBRmax、TBRmean]、胆碱：肌酸比[Cho：Cr 比]、归一化相对脑血容量[N rCBVmean]和表观扩散系数[ADCmean]。使用 Pearson 系数评估相关性。使用独立 t 检验和接收器操作曲线（ROC）分析评估每个参数的准确性，同时使用多元方差分析（MANOVA）评估四个参数联合用于区分复发与放射性坏死的能力。阳性组织病理学和影像学/临床随访作为金标准。
32 例患者中，24 例被诊断为复发性疾病，8 例为放射性坏死。TBRmax 与 N rCBVmean（ρ=0.503；P=0.003）、TBRmean 与 N rCBVmean（ρ=0.414；P=0.018）、TBRmax 与 ADCmean（ρ=-0.52；P=0.002）和 TBRmean 与 ADCmean（ρ=-0.518；P=0.002）之间存在显著相关性。TBRmax、TBRmean、ADCmean、Cho：Cr 比值和 N rCBVmean 对区分复发与放射性坏死具有显著意义，准确性分别为 94.1%、88.2%、80.4%、96.4%和 89.9%。MANOVA 表明，与任何单一参数相比，所有参数的组合对复发与坏死的评估效果更好。使用所有 MRI 参数的诊断准确性、敏感性和特异性分别为 93.75%、96%和 85.7%，使用所有 FET PET/MRI 参数的诊断准确性、敏感性和特异性分别为 96.87%、100%和 85.7%。
除 FET PET 摄取外，多个 MRI 参数的协同作用突出表明，整合 18F-FET PET/MRI 有可能通过及时、明确地识别真性复发与放射性坏死，对胶质瘤患者的治疗管理产生影响。
