Combination of MRI and dynamic FET PET for initial glioma grading

Abstract

SummaryAim: MRI and PET with 18 F-fluoro-ethyl-tyrosine (FET) have been increasingly used to evaluate patients with gliomas. Our purpose was to assess the additive value of MR spectroscopy (MRS), diffusion imaging and dynamic FET-PET for glioma grading. Patients, methods: 38 patients (42 ± 15 aged, F/M: 0.46) with untreated histologically proven brain gliomas were included. All underwent conventional MRI, MRS, diffusion sequences, and FET-PET within 3±4 weeks. Performances of tumour FET time-activity-curve, early-to-middle SUVmax ratio, choline / creatine ratio and ADC histogram distribution pattern for gliomas grading were assessed, as compared to histology. Combination of these parameters and respective odds were also evaluated. Results: Tumour time-activitycurve reached the best accuracy (67%) when taken alone to distinguish between low and high-grade gliomas, followed by ADC histogram analysis (65%). Combination of timeactivity-curve and ADC histogram analysis improved the sensitivity from 67% to 86% and the specificity from 63-67% to 100% (p < 0.008). On multivariate logistic regression analysis, negative slope of the tumour FET time-activity-curve however remains the best predictor of high-grade glioma (odds 7.6, SE 6.8, p = 0.022). Conclusion: Combination of dynamic FET-PET and diffusion MRI reached good performance for gliomas grading. The use of FET-PET/MR may be highly relevant in the initial assessment of primary brain tumours.

The Sum of Tumour-to-Brain Ratios Improves the Accuracy of Diagnosing Gliomas Using 18F-FET PET

“…Using this approach, there was only one false negative case out of the 46 examined, equating to 97% PET sensitivity. These results are consistent with the 92% PET sensitivity observed by Pauleit et al, and are slightly better than those presented in a meta-analysis (82%) examining the use of FET PET to distinguish brain tumours from non-malignant lesions [ 9 ]. It should be emphasised that our study included only patients with a strong suspicion of gliomas on MRI, while studies included in the meta-analysis used various criteria for defining FET PET positivity.…”

“…The threshold value of 1.75 for rCBV provides a sensitivity and specificity of 95.0% and 57.5%, respectively. The combination of rCBV and MRS resulted in a sensitivity and specificity of 93.3% and 60.0%, respectively [ 25 ], while the combination of diffusion MRI and dynamic PET revealed improved sensitivity (67–86%) and specificity (63–67% to 100%) [ 9 ]. However, even the combined MRI and PET modalities assessed in the latter study were of lower accuracy than TBR sum defined using dynamic PET alone, as reported here.…”

“…For CNS diagnostics, 18F-FET has advantages over other radiotracers due to its high stability in vitro and in vivo , fast tumour kinetics, low susceptibility to accumulation in healthy tissues, straightforward synthesis, and long half-life [ 4 – 7 ]. 18F-FET PET is a proven tool in the differential diagnosis of malignant and benign brain tumours [ 8 , 9 ], with PET-guided biopsies confirming the technique’s diagnostic efficacy for the detection of the solid components of gliomas and their microscopic infiltration [ 10 ]. Various parameters describing 18F-FET uptake in a tumour mass have been published.…”

From PET/CT to PET/MRI: Advances in Instrumentation and Clinical Applications

“…In Dunvet's study, 38 glioma patients underwent conventional MRI, MRS, diffusion sequences, and fluoroethyltyrosine PET (FET-PET). 76 The tumor time− activity curve reached the best accuracy by distinguishing between low-and high-grade gliomas followed by ADC histogram analysis. Combining the time−activity curve and ADC histogram analyses improved the sensitivity from 67% to 86% and the specificity from 63−67% to 100%.…”

PET/MRI in Oncological Imaging: State of the Art

“…, metastasectomy, whole brain radiation, or gamma-knife surgery). Studies have shown that PET/MRI with brain tumor-targeted tracers such as [ 11 C]methionine and 18 F-fluoro-ethyl-tyrosine ( 18 F-FET) is feasible, and is as accurate as PET/CT [ 26 , 27 ]. However, most studies describe imaging of primary brain tumors, and there is a paucity of data on brain metastases.…”