Dual-time-point O-(2-[18F]fluoroethyl)-L-tyrosine PET for grading of cerebral gliomas

We aimed to evaluate the diagnostic potential of dual-time-point imaging with positron emission tomography (PET) using O-(2-[F-18]fluoroethyl)-L-tyrosine (F-18-FET) for non-invasive grading of cerebral gliomas compared with a dynamic approach. Thirty-six patients with histologically confirmed cerebral gliomas (21 primary, 15 recurrent; 24 high-grade, 12 low-grade) underwent dynamic PET from 0 to 50 min post-injection (p.i.) of F-18-FET, and additionally from 70 to 90 min p.i. Mean tumour-to-brain ratios (TBRmean) of F-18-FET uptake were determined in early (20-40 min p.i.) and late (70-90 min p.i.) examinations. Time-activity curves (TAC) of the tumours from 0 to 50 min after injection were assigned to different patterns. The diagnostic accuracy of changes of F-18-FET uptake between early and late examinations for tumour grading was compared to that of curve pattern analysis from 0 to 50 min p.i. of F-18-FET. The diagnostic accuracy of changes of the TBRmean of F-18-FET PET uptake between early and late examinations for the identification of HGG was 81 % (sensitivity 83 %; specificity 75 %; cutoff - 8 %; p < 0.001), and 83 % for curve pattern analysis (sensitivity 88 %; specificity 75 %; p < 0.001). Dual-time-point imaging of F-18-FET uptake in gliomas achieves diagnostic accuracy for tumour grading that is similar to the more time-consuming dynamic data acquisition protocol. Dual-time-point imaging is equivalent to dynamic FET PET for grading of gliomas. Dual-time-point imaging is less time consuming than dynamic FET PET. Costs can be reduced due to higher patient throughput. Reduced imaging time increases patient comfort and sedation might be avoided. Quicker image interpretation is possible, as no curve evaluation is necessary.