Article
[18F]fluoroethyl-tyrosine (FET) PET vs. stereotactic biopsy in patients with multimodally treated gliomas: impact on treatment decision
[18F]fluoroethyl-tyrosine (FET) PET vs. stereotaktische Biopsie bei Patienten mit multimodal behandelten Gliomen: Einfluss auf die Therapieentscheidung
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Published: | May 8, 2006 |
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Objective: FET-PET has been reported to offer a powerful diagnostic tool, when differentiating between tumor- and therapy-associated contrast enhancement on MRI in patients with multimodally treated gliomas is difficult. Notwithstanding these promising results, there might be a considerable risk of false positive FET-PET investigations in these patients. This issue, which might have important consequences with regard to further treatment strategies, has not been adequately addressed so far. Therefore, the current prospective study was undertaken.
Methods: A selected group of 35 glioma-patients treated with multimodal therapy between 12/2003 and 11/2004 and with suspected recurrence/tumor progression both on MRI and FET-PET were included. The criterion for tumor recurrence/progression was a standardized uptake value (SUVmax) of >2.2. This threshold was suggested based on a previously performed comparative evaluation of PET and histological data. A stereotactic serial biopsy (including specimens from the “hotspot” area as defined by the SUVmax) with a multimodal (CT, MRT, FET-PET) 3D-treatment-planning was performed in all patients. Both histology and FET-PET findings were correlated with clinical follow-up.
Results: In 30 Patients (12 WHO grade II, 7 WHO grade III, 11 WHO grade IV) FET-PET results indicating a tumor recurrence were concordant with histology as well as the clinical follow-up. In 5 patients (3 WHO grade II, 1 WHO grade III, 1 WHO grade IV) in which FET-PET was highly suspicious for tumor recurrence and/or progression, histopathologic evaluation failed to reveal tumor progression/tumor recurrence. The FET-PET findings in these 5 patients also did not correlated with the clinical follow-up (lack of any progressive symptoms).
Conclusions: In selected patients with positive concordant findings of FET-PET and MRI with regard to tumor recurrence/tumor progression, any further treatment should be based on histological re-evaluation.