O-(2-¹⁸F-Fluoroethyl)-L-Tyrosine PET Predicts Failure of Antiangiogenic Treatment in Patients with Recurrent High-Grade Glioma

Abstract

The objective of this study was to compare MRI response assessment with metabolic O-(2-18 F-fluoroethyl)-L-tyrosine ( 18 F-FET) PET response evaluation during antiangiogenic treatment in patients with recurrent high-grade glioma (rHGG). Methods: Eleven patients with rHGG were treated biweekly with bevacizumab-irinotecan. MR images and 18 F-FET PET scans were obtained at baseline and at follow-up 8-12 wk after treatment onset. MRI treatment response was evaluated by T1/T2 volumetry according to response assessment in neurooncology (RANO) criteria. For 18 F-FET PET evaluation, an uptake reduction of more than 45% calculated with a standardized uptake value of more than 1.6 was defined as a metabolic response (receiver-operating-characteristic curve analysis). MRI and 18 F-FET PET volumetry results and response assessment were compared with each other and in relation to progression-free survival (PFS) and overall survival (OS). Results: At follow-up, MR images showed partial response in 7 of 11 patients (64%), stable disease in 2 of 11 patients (18%), and tumor progression in 2 of 11 patients (18%). In contrast, 18 F-FET PET revealed 5 of 11 metabolic responders (46%) and 6 of 11 nonresponders (54%). MRI and 18 F-FET PET showed that responders survived significantly longer than did nonresponders (10.24 vs. 4.1 mo, P 5 0.025, and 7.9 vs. 2.3 mo, P 5 0.015, respectively). In 4 patients (36.4%), diagnosis according to RANO criteria and 18 F-FET PET was discordant. In these cases, PET was able to detect tumor progression earlier than was MRI. Conclusion: In rHGG patients undergoing antiangiogenic treatment, 18 F-FET PET seems to be predictive for treatment failure in that it contributes important information to response assessment based solely on MRI and RANO criteria.

PET Imaging in Glioblastoma: Use in Clinical Practice

“…Responders based on 18 F-FDOPA PET data survived 3.5 times longer (12.1 months vs. 3.5 months of median overall survival) than nonresponders, which was much higher than responders based solely on MRI (90). Similar results have been reported for 18 F-FET (92)(93)(94).…”

18F-FCho PET and MRI for the prediction of response in glioblastoma patients according to the RANO criteria

“…The threshold also yielded a good discriminative power to separate prognostic groups in terms of progression-free and overall survival [14]. Hutterer et al [27] reported a decrease of 45% of MTV to define metabolic response in recurrent high-grade glioma patients treated with bevacizumab and irinotecan. For 18 F-FLT PET, more than 25% reduction in tumor SUV uptake was defined as a metabolic response in patients with recurrent malignant gliomas treated with bevacizumab and irinotecan [28].…”

Dynamic 18F-FET PET in Newly Diagnosed Astrocytic Low-Grade Glioma Identifies High-Risk Patients

“…Therefore, the fluorinated amino acid analog 18 F-FET has emerged as a powerful complementary tool for glioma imaging (21,22). 18 F-FET PET was shown to be useful for biopsy and treatment planning by accurate delineation of the tumor borders and demarcation of most malignant tumor parts (11,21,(23)(24)(25) and for subsequent treatment monitoring including differentiation between benign therapyinduced changes and tumor recurrence (13,18,(26)(27)(28). Furthermore, the additional use of kinetic analysis of 18 F-FET PET was shown to enable more accurate tumor grading, even in individual patients: increasing time-activity curves are considered to be associated with less malignant low-grade glioma tissue, whereas decreasing timeactivity curves were shown to be prevalent in more aggressive high-grade glioma tissue (9,10).…”