Department of Nuclear Medicine, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany.
Department of Neurosurgery, University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany.
Eur J Nucl Med Mol Imaging. 2018 Jul;45(7):1242-1249. doi: 10.1007/s00259-018-3969-4. Epub 2018 Feb 27.
For the clinical evaluation of O-(2-F-fluoroethyl)-L-tyrosine (F-FET) PET images, the use of standard summation images obtained 20-40 min after injection is recommended. However, early summation images obtained 5-15 min after injection have been reported to allow better differentiation between low-grade glioma (LGG) and high-grade glioma (HGG) by capturing the early F-FET uptake peak specific for HGG. We compared early and standard summation images with regard to delineation of the PET-derived biological tumour volume (BTV) in correlation with the molecular genetic profile according the updated 2016 WHO classification.
The analysis included 245 patients with newly diagnosed, histologically verified glioma and a positive F-FET PET scan prior to any further treatment. BTVs were delineated during the early 5-15 min and standard 20-40 min time frames using a threshold of 1.6 × background activity and were compared intraindividually. Volume differences between early and late summation images of >20% were considered significant and were correlated with WHO grade and the molecular genetic profile (IDH mutation and 1p/19q codeletion status).
In 52.2% of the patients (128/245), a significant difference in BTV of >20% between early and standard summation images was found. While 44.3% of WHO grade II gliomas (31 of 70) showed a significantly smaller BTV in the early summation images, 35.0% of WHO grade III gliomas (28/80) and 37.9% of WHO grade IV gliomas (36/95) had a significantly larger BTVs. Among IDH-wildtype gliomas, an even higher portion (44.4%, 67/151) showed significantly larger BTVs in the early summation images, which was observed in 5.3% (5/94) of IDH-mutant gliomas only: most of the latter had significantly smaller BTVs in the early summation images, i.e. 51.2% of IDH-mutant gliomas without 1p/19q codeletion (21/41) and 39.6% with 1p/19q codeletion (21/53).
BTVs delineated in early and standard summation images differed significantly in more than half of gliomas. While the standard summation images seem appropriate for delineation of LGG as well as IDH-mutant gliomas, a remarkably high percentage of HGG and, particularly, IDH-wildtype gliomas were depicted with significantly larger volumes in early summation images. This finding might be of interest for optimization of treatment planning (e.g. radiotherapy) in accordance with the individual IDH mutation status.
对于 O-(2-F-氟乙基)-L-酪氨酸（F-FET）PET 图像的临床评估，建议使用注射后 20-40 分钟获得的标准总和图像。然而，据报道，注射后 5-15 分钟获得的早期总和图像通过捕获针对 HGG 的早期 F-FET 摄取峰值，可更好地区分低级别胶质瘤（LGG）和高级别胶质瘤（HGG）。我们比较了早期和标准总和图像，以根据 2016 年 WHO 分类的最新分子遗传学特征来描绘 PET 衍生的生物肿瘤体积（BTV）。
分析包括 245 名新诊断、组织学证实的胶质瘤患者，以及在任何进一步治疗前进行了阳性 F-FET PET 扫描。使用 1.6×背景活动的阈值在早期 5-15 分钟和标准 20-40 分钟的时间范围内描绘 BTV，并进行个体内比较。早期和晚期总和图像之间体积差异>20% 被认为具有统计学意义，并与 WHO 分级和分子遗传学特征（IDH 突变和 1p/19q 缺失状态）相关。
在 52.2%的患者（128/245）中，早期和标准总和图像之间的 BTV 差异>20%。44.3%的 WHO 二级胶质瘤（31/70）在早期总和图像中显示出明显较小的 BTV，而 35.0%的 WHO 三级胶质瘤（28/80）和 37.9%的 WHO 四级胶质瘤（36/95）则显示出明显较大的 BTV。在 IDH 野生型胶质瘤中，甚至有更高比例（44.4%，67/151）在早期总和图像中显示出明显较大的 BTV，而 IDH 突变型胶质瘤中只有 5.3%（5/94）观察到这种情况：后者中大部分在早期总和图像中 BTV 明显较小，即 51.2%的 IDH 突变型无 1p/19q 缺失的胶质瘤（21/41）和 39.6%的有 1p/19q 缺失的胶质瘤（21/53）。
在超过一半的胶质瘤中，早期和标准总和图像描绘的 BTV 差异显著。虽然标准总和图像似乎适合于 LGG 以及 IDH 突变型胶质瘤的描绘，但 HGG，特别是 IDH 野生型胶质瘤的比例明显较高，在早期总和图像中描绘的体积明显较大。这一发现可能有助于根据个体的 IDH 突变状态优化治疗计划（例如放疗）。
