Performance of 18F-FET versus 18F-FDG-PET for the diagnosis and grading of brain tumors: systematic review and meta-analysis

Abstract

Background: For the past decade (18)F-fluoro-ethyl-l-tyrosine (FET) and (18)F-fluoro-deoxy-glucose (FDG) positron emission tomography (PET) have been used for the assessment of patients with brain tumor. However, direct comparison studies reported only limited numbers of patients. Our purpose was to compare the diagnostic performance of FET and FDG-PET.

Methods: We examined studies published between January 1995 and January 2015 in the PubMed database. To be included the study should: (i) use FET and FDG-PET for the assessment of patients with isolated brain lesion and (ii) use histology as the gold standard. Analysis was performed on a per patient basis. Study quality was assessed with STARD and QUADAS criteria.

Results: Five studies (119 patients) were included. For the diagnosis of brain tumor, FET-PET demonstrated a pooled sensitivity of 0.94 (95% CI: 0.79-0.98) and pooled specificity of 0.88 (95% CI: 0.37-0.99), with an area under the curve of 0.96 (95% CI: 0.94-0.97), a positive likelihood ratio (LR+) of 8.1 (95% CI: 0.8-80.6), and a negative likelihood ratio (LR-) of 0.07 (95% CI: 0.02-0.30), while FDG-PET demonstrated a sensitivity of 0.38 (95% CI: 0.27-0.50) and specificity of 0.86 (95% CI: 0.31-0.99), with an area under the curve of 0.40 (95% CI: 0.36-0.44), an LR+ of 2.7 (95% CI: 0.3-27.8), and an LR- of 0.72 (95% CI: 0.47-1.11). Target-to-background ratios of either FDG or FET, however, allow distinction between low- and high-grade gliomas (P > .11).

Conclusions: For brain tumor diagnosis, FET-PET performed much better than FDG and should be preferred when assessing a new isolated brain tumor. For glioma grading, however, both tracers showed similar performances.

Keywords: 18F-fluoro-deoxy-glucose; 18F-fluoro-ethyl-tyrosine; PET; brain tumor; meta-analysis.

Fig. 1.

Flowchart of study selection.

Fig. 2.

ROC curves for discrimination between brain tumoral and nontumoral lesion for FDG-PET and FET-PET (n = 119 patients). Dashed line indicates FDG-PET; solid line indicates FET-PET; fine dashed line indicates chance.

Fig. 3.

Forest plot of studies included in the meta-analysis for discrimination between glioma vs nonglioma lesions with FDG-PET.

Fig. 4.

Study quality grading using QUADAS scores (range 0–14) and STARD scores (range 0–25). *Studies included in the meta-analysis. Dashed line indicates maximal score for QUADAS.

Fig. 5.

TBR comparison according to histologic WHO grading. Light gray and medium light gray indicate mean TBR and maximum TBR from FDG-PET; medium dark and dark gray indicate mean TBR and maximum TBR from FET-PET. *P = .0028 vs WHO grades I–II; **P = .0065 vs WHO grades I–II, ^||P = .0001 vs WHO grades I–II. For comparison between nontumoral lesions and WHO grades I–II gliomas, all P-values >.44.