NCI-Sponsored Trial for the Evaluation of Safety and Preliminary Efficacy of 3′-Deoxy-3′-[18F]fluorothymidine (FLT) as a Marker of Proliferation in Patients with Recurrent Gliomas: Preliminary Efficacy Studies
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3′-Deoxy-3′-[18F]fluorothymidine ([18F]FLT) is being developed for imaging cellular proliferation. The goals were to explore the capacity of FLT-positron emission tomography (PET) to distinguish between recurrence and radionecrosis in gliomas and compare the results to those obtained with 2-fluoro-2-deoxy-d-glucose (FDG).
Fifteen patients with tumor recurrence and four with radionecrosis, determined by clinical course and magnetic resonance imaging results, were studied by dynamic [18F]FLT-PET with arterial blood sampling. A two-tissue compartment four-rate constant model was used to determine metabolic flux (KFLT), blood to tissue transport (K1), and phosphorylation (k3). FDG-PET scans were obtained 75–90 min postinjection.
KFLT and k3, but not K1 or k3/k2 + k3, reached significance for separating the recurrence from radionecrosis groups. Standardized uptake value and visual analyses of FLT or FDG images did not reach significance.
KFLT (flux) appears to distinguish recurrence from radionecrosis better than other parameters, FLT and FDG semiquantitative approaches, or visual analysis of images of either tracer.