Recurrent glioblastoma versus late posttreatment changes: diagnostic accuracy of O-(2-[18F]fluoroethyl)-L-tyrosine positron emission tomography (18F-FET PET)

Abstract

Background Diagnostic accuracy in previous studies of O-(2-[18F]-fluoroethyl)-L-tyrosine (18F-FET) PET in patients with suspected recurrent glioma may be influenced by prolonged dynamic PET acquisitions, heterogeneous populations, different non–standard-of-care therapies, and PET scans performed at different time points post radiotherapy. We investigated the diagnostic accuracy of a 20-minute 18F-FET PET scan in MRI-suspected recurrent glioblastoma 6 months after standard radiotherapy and its ability to prognosticate overall survival (OS). Methods In total, 146 glioblastoma patients with 168 18F-FET PET scans were reviewed retrospectively. Patients with MRI responses to bevacizumab or undergoing re-irradiation or immunotherapy after 18F-FET PET were excluded. Maximum and mean tumor-to-background ratios (TBRmax, TBRmean) and biological tumor volume (BTV) were recorded and verified by histopathology or clinical/radiological follow-up. Thresholds of 18F-FET parameters were determined by receiver operating characteristic (ROC) analysis. Prognostic factors were investigated in Cox proportional hazards models. Results Surgery was performed after 104 18F-FET PET scans, while clinical/radiological surveillance was used following 64, identifying 152 glioblastoma recurrences and 16 posttreatment changes. ROC analysis yielded thresholds of 2.0 for TBRmax, 1.8 for TBRmean, and 0.55 cm3 for BTV in differentiating recurrent glioblastoma from posttreatment changes with the best performance of TBRmax (sensitivity 99%, specificity 94%; P < 0.0001) followed by BTV (sensitivity 98%, specificity 94%; P < 0.0001). Using these thresholds, 166 18F-FET PET scans were correctly classified. Increasing BTV was associated with shorter OS (P < 0.0001). Conclusion A 20-minute 18F-FET PET scan is a powerful tool to distinguish posttreatment changes from recurrent glioblastoma 6-month postradiotherapy, and predicts OS.

Sequential implementation of DSC-MR perfusion and dynamic [18F]FET PET allows efficient differentiation of glioma progression from treatment-related changes

“…The same holds true when comparing the tumor uptake to that of inflammatory processes [ 11 ]. Previous studies specifically investigating the differentiation of TP and TRC in glioma [ 12 – 16 ] reported diagnostic accuracies of [ 18 F]FET PET between 81% [ 17 ] and 99% [ 18 ]. This considerable range could be attributed to the analysis of different PET parameters and the particular patient populations, varying in tumor subtypes and treatments.…”

Identify glioma recurrence and treatment effects with triple-tracer PET/CT

“…However, another study suggests that increased uptake of 11 C-MET, such as 18 F-FDG, may have limited speci city in distinguishing in ammatory lesions from tumours [26]. Bashir et al [27] found that a 20-minute 18 F-FET PET scan is a powerful tool with TBRmax (sensitivity 99%, speci city 94%) to distinguish posttreatment changes from recurrent glioblastoma 6 months postradiotherapy. Bogsrud et al [28] reported the performance of a new type of amino acid 18 F-uciclovine in PET/CT of suspected residual or recurrent glioma, but the ability of 18 F-uciclovine PET/CT to discriminate between recurrent glioma and treatment-related changes could not be determined because no patients had con rmed treatment-related changes.…”

Identify glioma recurrence and treatment effects with triple-tracer PET/CT

“…However, another study suggests that increased uptake of 11 C-MET, such as 18 F-FDG, may have limited speci city in distinguishing in ammatory lesions from tumours[26]. Bashir et al [27] found that a 20-minute 18 F-FET PET scan is a powerful tool with TBRmax (sensitivity 99%, speci city 94%) to distinguish posttreatment changes from recurrent glioblastoma 6 months postradiotherapy. Bogsrud et al [28] reported the performance of a new type of amino acid 18 F-uciclovine in PET/CT of suspected residual or recurrent glioma, but the ability of 18 F-uciclovine PET/CT to discriminate between recurrent glioma and treatment-related changes could not be determined because no patients had con rmed treatment-related changes.…”