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Evaluation of primary brain tumors with F-TYR and FDG PET: Correlation with pathology and survival

¹ CHU, Liège, Belgium; ; ² CHR, Liège, Belgium; ; ³ University of Liège, Liège, Belgium

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Objectives: To evaluate PET with 2-18F-fluoro-L-tyrosine (F-TYR) and FDG for assessing tumor grade and survival in primary brain tumors.

Methods: Data obtained in 42 consecutive patients (24 M, 18 W) were reviewed. Pathology obtained at surgery (n=18) or by biopsy (n=24) was: Astrocytoma (Gr. I, n=2; Gr II n=18; Gr III n=5; Gr IV n=6), oligoastrocytoma (Gr II n=2; Gr III n=1), oligodendroglioma (Gr II n=3, Gr III n=4) and 1 ganglioglioma Gr II. All pts were imaged prior to any treatment. PET was performed 30±10 min. (avg±SD) after injecting 307±33 MBq F-TYR. Forty pts also had FDG-PET. Tumor to cortex activity ratios (T/C) were obtained by drawing ROIs over the most active transaxial slice in the tumor and over the contralateral parietal cortex. An ROC analysis was performed to assess the optimal cut-off value for differentiating low-grade and high-grade tumors. Kaplan-Meier survival curves were established according to the median value of the activity ratios.

Results: The T/C were significantly higher with F-TYR than with FDG, especially for low-grade tumors (1.7 Vs 0.6). Both F-TYR and FDG T/C were higher (P<0.05 and <0.001, respectively) in high grade lesions, but only after excluding oligodendrogliomas, which were all active (F-TYR: 2.5; FDG: 1.2). The optimal cut-off for tumor grades was 1.98 with F-TYR (AUC 0.673) and 0.7 with FDG (AUC 0.771). Without the oligodendrogliomas, the AUC increased to 0.731 and 0.875, respectively. The median follow up was 720 days (range 166-1793). Thirteen patients deceased. According to the Kaplan-Meier survival curves, FDG uptake, but not F-TYR, was predictive of the outcome.

Conclusions: Although F-TYR allows a better tumor to background contrast in low-grade gliomas, FDG remains useful for characterizing the tumor grade and predicting the outcome.

Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Lovinfosse, P. Articles by Hustinx, R. PubMed Articles by Lovinfosse, P. Articles by Hustinx, R.