Article
FET PET in diagnosis of glioma recurrence after multimodal therapy: Is evaluation of uptake kinetics superior to standard ratio methods?
FET PET in der Diagnostik von Gliom-Rezidiven nach multimodaler Therapie: Ist die Analyse der Aufnahme-Kinetik der Standard-Ratio-Methode überlegen?
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Published: | May 8, 2006 |
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Objective: Extended analyses of [18F]fluoroethyltyrosine (FET) uptake kinetics were shown to render valuable information in the identification/grading of primary gliomas. The aim of this study was to evaluate, whether dynamic analyses also provide superior results compared to standard tumor/background ratios in predicting tumor grade and/or recurrence in patients with multimodally treated low and high grade gliomas.
Methods: Dynamic FET-PET studies (0-40 min p.i. of 180 MBq FET) were performed in 45 glioma patients (26 WHO II, 7 WHO III, 12 WHO IV) after multimodal therapy with the MRI-based diagnosis (contrast-enhancing lesion) of tumor-recurrence/progression. For the standard method, the tumoral standard uptake value (SUVmax) and the ratio to the background (SUVmax/BG) were derived from a sum image (20 to 40 min p.i.). Dynamic data evaluation consisted of several approaches, including: a) SUV within a 90% isocontour threshold (SUV90) and the respective ratio to the background (SUV90/BG) and b) time to peak analysis. All results were correlated with histopathological findings derived from stereotactic serial biopsies with multimodal (CT, MRI, FET-PET) 3D-trajectory-planning.
Results: The standard method was able to differentiate patients without recurrence (4 patients) from those with recurrent tumors (41 patients). In patients with detected tumor progression/tumor recurrence, the time curves for SUV and SUV/BG ratios between 5 and 40 min p.i. increased slightly and steadily in low grade tumors whereas high grade tumors presented with an early peak arround 10 to 15 min p.i. followed by a decrease thereafter. The calculated sensitivity and specificity for the dynamic analysis was 92%, respectively. The corresponding values for the standard method were sigfnificantly lower (SUVmax/BG: sensitivity and specifity of 62%, respectively).
Conclusions: Analysis of kinetics of FET uptake seems to permit discrimination of tumor-grade in recurrent gliomas after multimodal therapy with high diagnostic accuracy and should thus be considered a valuable complementation to the standard tumor/background ratios.