PDF(Pubmed)
Abstract：
Accurately defining glioma infiltration is crucial for optimizing radiotherapy and surgery, but glioma infiltration is heterogeneous and MRI imperfectly defines the tumor extent. Currently, it is impossible to determine the tumor infiltration gradient within a FLAIR signal. O-(2-[18F]fluoroethyl)-L-tyrosine (FET)-PET often reveals high-grade glioma infiltration beyond contrast-enhancing areas on MRI. Here, we studied FET uptake dynamics in tumor and normal brain structures by dual-timepoint (10 min and 40-60 min post-injection) acquisition to optimize analysis protocols for defining glioma infiltration. Over 300 serial stereotactic biopsies from 23 patients (mean age 47, 12 female/11 male) of diffuse contrast-enhancing gliomas were taken from areas inside and outside contrast enhancement or outside the FET hotspot but inside FLAIR. The final diagnosis was G4 in 11, grade 3 in 10, and grade 2 in 2 patients. The target-to-background (TBRs) ratios and standardized uptake values (SUVs) were calculated in areas used for biopsy planning and in background structures. The optimal method and threshold values were determined to find a preferred strategy for defining glioma infiltration. Standard thresholding (1.6× uptake in the contralateral brain) in standard acquisition PET images differentiated a tumor of any grade from astrogliosis, although the uptake in astrogliosis and grade 2 glioma was similar. Analyzing an optimal strategy for infiltration volume definition astrogliosis could be accurately differentiated from tumor samples using a choroid plexus as a background. Early acquisition improved the AUC in many cases, especially within FLAIR, from 56% to 90% sensitivity and 41% to 61% specificity (standard TBR 1.6 vs. early TBR plexus). The current FET-PET evaluation protocols for contrast-enhancing gliomas are limited, especially at the tumor border where grade 2 tumor and astrogliosis have similar uptake, but using choroid plexus uptake in early acquisitions as a background, we can precisely define a tumor within FLAIR that was outside of the scope of current FET-PET protocols.
摘要：
准确定义胶质瘤浸润对于优化放疗和手术至关重要，但是神经胶质瘤浸润是不均匀的，MRI不完全定义了肿瘤的范围。目前,无法确定FLAIR信号内的肿瘤浸润梯度。O-（2-[18F]氟乙基）-L-酪氨酸（FET）-PET通常在MRI上显示出超出对比增强区域的高级胶质瘤浸润。这里,我们通过双时间点(注射后10分钟和40-60分钟)采集研究了肿瘤和正常脑结构中的FET摄取动力学,以优化定义神经胶质瘤浸润的分析方案.来自23例弥漫性对比增强神经胶质瘤患者（平均年龄47岁，女性12例/男性11例）的300多例连续立体定向活检取自对比增强内部和外部或FET热点外部但在FLAIR内部的区域。最终诊断为11例患者为G4，10例患者为3级，2例患者为2级。在用于活检计划的区域和背景结构中计算目标背景（TBR）比和标准化摄取值（SUV）。确定了最佳方法和阈值，以找到定义神经胶质瘤浸润的首选策略。标准采集PET图像中的标准阈值（对侧大脑中的1.6倍摄取）将任何级别的肿瘤与星形胶质增生区分开，尽管星形胶质细胞增生和2级神经胶质瘤的摄取相似。使用脉络丛作为背景，分析浸润体积定义星形胶质细胞增生的最佳策略可以与肿瘤样品准确区分。在许多情况下，早期收购改善了AUC，尤其是在FLAIR内部,从56%到90%的灵敏度和41%到61%的特异性(标准TBR1.6与早期TBR神经丛）。目前用于对比增强神经胶质瘤的FET-PET评估方案是有限的，特别是在2级肿瘤和星形胶质增生有相似的摄取的肿瘤边界，但是使用早期采集的脉络丛吸收作为背景，我们可以在FLAIR中精确定义超出当前FET-PET方案范围的肿瘤。
