An Interindividual Comparison of O-(2- [{sup 18}F]Fluoroethyl)-L-Tyrosine (FET)- and L-[Methyl-{sup 11}C]Methionine (MET)-PET in Patients With Brain Gliomas and Metastases
- Department of Radiation Oncology, Albert Ludwigs Universitaet Freiburg, Freiburg (Germany)
- Department of Radiation Oncology, Klinikum Rechts der Isar, Technische Universitaet Muenchen, Munich (Germany)
- Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universitaet Muenchen, Munich (Germany)
Purpose: L-[methyl-{sup 11}C]methionine (MET)-positron emission tomography (PET) has a high sensitivity and specificity for imaging of gliomas and metastatic brain tumors. The short half-life of {sup 11}C (20 minutes) limits the use of MET-PET to institutions with onsite cyclotron. O-(2- [{sup 18}F]fluoroethyl)-L-tyrosine (FET) is labeled with {sup 18}F (half-life, 120 minutes) and could be used much more broadly. This study compares the uptake of FET and MET in gliomas and metastases, as well as treatment-induced changes. Furthermore, it evaluates the gross tumor volume (GTV) of gliomas defined on PET and magnetic resonance imaging (MRI). Methods and Materials: We examined 42 patients with pretreated gliomas (29 patients) or brain metastases (13 patients) prospectively by FET- and MET-PET on the same day. Uptake of FET and MET was quantified by standardized uptake values. Imaging contrast was assessed by calculating lesion-to-gray matter ratios. Tumor extension was quantified by contouring GTV in 17 patients with brain gliomas. Gross tumor volume on PET was compared with GTV on MRI. Sensitivity and specificity of MET- and FET-PET for differentiation of viable tumor from benign changes were evaluated by comparing the PET result with histology or clinical follow-up. Results: There was a strong linear correlation between standardized uptake values calculated for both tracers in cortex and lesions: r = 0.78 (p = 0.001) and r = 0.84 (p < 0.001), respectively. Image contrast was similar for MET- and FET-PET (lesion-to-gray matter ratios of 2.36 {+-} 1.01 and 2.33 {+-} 0.77, respectively). Mean GTV in 17 glioma patients was not significantly different on MET- and FET-PET. Both MET- and FET-PET delineated tumor tissue outside of MRI changes. Both tracers provided differentiated tumor tissue and treatment-related changes with a sensitivity of 91% at a specificity of 100%. Conclusions: O-(2- [{sup 18}F]fluoroethyl)-L-tyrosine-PET and MET-PET provide comparable diagnostic information on gliomas and brain metastases. Like MET-PET, FET-PET can be used for differentiation of residual or recurrent tumor from treatment-related changes/pseudoprogression, as well as for delineation of gliomas.
- OSTI ID:
- 22054409
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 81, Issue 4; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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