Article
O-(2-18F-fluoroethyl)-L-tyrosine (FET) uptake kinetic with parametric mapping is superior in predicting tumor grade in gliomas
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Published: | September 16, 2010 |
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Objective: Treatment and prognosis of gliomas depends on tumor grade. We investigated whether extended analyses of O-(2-18F-fluoroethyl)-L-tyrosine (FET) uptake kinetics provide results superior to those of standard tumor-to-background ratios in predicting tumor grade in glioma patients.
Methods: For standard evaluation areas of FET uptake with a lesion/brain ratio of 1.6 or more were considered indicators of tumor in 120 patients. For dynamic evaluation, maximum of FET uptake in lesion in relation to normal brain tissue were determined for each time frame (0–40 min post-injection). Results were correlated with histopathological findings from PET-guided biopsies – either obtained stereotactically or during resection – and MRI findings. Overall survival (OAS) was determined and correlated with FET kinetics.
Results: Histology revealed gliomas in all patients. Standard evaluation demonstrated a statistically significant difference (p=0.0014) between low (LGG) (n=42; mean lesion/brain tissue ratio of FET uptake: 1.453±0.538) and high grade gliomas (HGG) (n=78; mean lesion/brain tissue ratio of FET uptake 2.323±0.754). Time activity curves showed slight increase in LGG, whereas HGG presented with an early peak (0–20 min) followed by a decrease. Dynamic evaluation successfully separated LGG from HGG with high diagnostic accuracy (sensitivity 96%/specificity 96%). OAS was significantly lower in the group of FET kinetic supposed and histologically confirmed HGG.
Conclusions: This study shows significant differences in the dynamics of FET uptake between low and high grade gliomas. Therefore, parameters addressing the different kinetic pattern allow discrimination with high diagnostic power between these prognostically different groups.