Prognostic value of pre-irradiation FET PET in patients with not completely resectable IDH-wildtype glioma and minimal or absent contrast enhancement

Abstract

In glioma patients, complete resection of the contrast-enhancing portion is associated with improved survival, which, however, cannot be achieved in a considerable number of patients. Here, we evaluated the prognostic value of O-(2-[18F]-fluoroethyl)-L-tyrosine (FET) PET in not completely resectable glioma patients with minimal or absent contrast enhancement before temozolomide chemoradiation. Dynamic FET PET scans were performed in 18 newly diagnosed patients with partially resected (n = 8) or biopsied (n = 10) IDH-wildtype astrocytic glioma before initiation of temozolomide chemoradiation. Static and dynamic FET PET parameters, as well as contrast-enhancing volumes on MRI, were calculated. Using receiver operating characteristic analyses, threshold values for which the product of paired values for sensitivity and specificity reached a maximum were obtained. Subsequently, the prognostic values of FET PET parameters and contrast-enhancing volumes on MRI were evaluated using univariate Kaplan–Meier and multivariate Cox regression (including the MTV, age, MGMT promoter methylation, and contrast-enhancing volume) survival analyses for progression-free and overall survival (PFS, OS). On MRI, eight patients had no contrast enhancement; the remaining patients had minimal contrast-enhancing volumes (range, 0.2–5.3 mL). Univariate analyses revealed that smaller pre-irradiation FET PET tumor volumes were significantly correlated with a more favorable PFS (7.9 vs. 4.2 months; threshold, 14.8 mL; P = 0.012) and OS (16.6 vs. 9.0 months; threshold, 23.8 mL; P = 0.002). In contrast, mean tumor-to-brain ratios and time-to-peak values were only associated with a longer PFS (P = 0.048 and P = 0.045, respectively). Furthermore, the pre-irradiation FET PET tumor volume remained significant in multivariate analyses (P = 0.043), indicating an independent predictor for OS. Our results suggest that pre-irradiation FET PET parameters have a prognostic impact in this subgroup of patients.

11C-methionine PET imaging characteristics in children with diffuse intrinsic pontine gliomas and relationship to survival

“…MTV re ects the size of the metabolically active tumour, while TLMU re ects both MTV and uptake intensity or the so-called tumour burden [37]. Both MTV and TLMU are commonly used to predict outcomes in patients with different types of brain tumour [37][38][39][40]. For DIPG, studies using these PET parameters to correlate with survival are limited.…”

Brain Tumor Classification Using a Combination of Variational Autoencoders and Generative Adversarial Networks

“…The uptake of radiolabeled amino acids is poor in normal brain tissue, in contrast to the widely used 18 F-FDG PET tracer, due to which tumors can be displayed with a strong tumor to background contrast. The ability of common amino acid tracers to penetrate through the intact BBB is one of their key characteristics, allowing for the depiction of the tumor that makes PET superior to contrast-enhanced MRI [11]. So, PET with radiolabeled amino acids is used as an alternative to the contrast-enhanced MRI for more exact tumor delineation [15].…”

“…Contrast-enhanced MRI plays a critical role in identifying, characterizing, and planning surgical tumor resection in patients with glioma. Any sign of contrast enhancement in early postoperative MRI (within 24–72 h) indicates incomplete resection [ 11 ]. A considerable number of patients could be misjudged with contrast-enhanced MRI, especially the patients with IDH-wildtype anaplastic glioma [ 12 ].…”

“…IDH (isocitrate dehydrogenase) is an important enzyme in the tricarboxylic acid cycle, and the tumors with normal IDH genes are referred to as “IDH wild-type” or “IDH negative” [ 13 ]. These IDH wild-type tumors are considered the most aggressive ones and lack contrast enhancement on MRI, so it may not be the best option for resection guidance [ 11 ]. Positron emission tomography (PET) scans have been considered recently in some clinical facilities to overcome the deficiency of contrast-enhanced MRI, particularly for the group of patients with IDH wild-type [ 11 ].…”

“…These IDH wild-type tumors are considered the most aggressive ones and lack contrast enhancement on MRI, so it may not be the best option for resection guidance [ 11 ]. Positron emission tomography (PET) scans have been considered recently in some clinical facilities to overcome the deficiency of contrast-enhanced MRI, particularly for the group of patients with IDH wild-type [ 11 ].…”