Authors: Sophia Koukouraki Ludwig G Strauss Vassilios Georgoulias Michael Eisenhut Uwe Haberkorn Antonia DimitrakopoulouStrauss
Publish Date: 2006/06/09
Volume: 33, Issue: 10, Pages: 1115-1122
Abstract
The purpose of this study was to evaluate and compare by means of dynamic PET the pharmacokinetics of 68GaDOTATOC a tracer which reflects the expression of somatostatin receptors SSTRs and of 18FFDG a marker of tumour viability in patients with metastatic neuroendocrine tumours NETs in whom 90YDOTATOC therapy was plannedFifteen patients 63 lesions with confirmed metastatic NETs were enrolled in this study Dynamic 18FFDG and 68GaDOTATOC PET scans were performed on two different days in the same week The data analysis was based on qualitative and quantitative analysis using a twotissue compartment model with a blood compartment and a noncompartment model based on the fractal dimension FD Multivariate analysis was used for evaluation of the kinetic dataEnhanced 18FFDG uptake was observed in 43/63 lesions 68GaDOTATOC showed pathologically enhanced uptake in all evaluated patients and in 57/63 lesions Discordant scintigraphic results for 18FFDG and 68GaDOTATOC were observed in 6/15 patients Global SUV was defined as the SUV measured in the last frame 55–60 min pi of the dynamic series for each tracer The median global SUV uptake was 79 for 68GaDOTATOC and 46 for 18FFDG The selection of patients for 90YDOTATOC therapy was based on the uptake of 68GaDOTATOC Multiple linear regression analysis was applied to determine the effect of each kinetic parameter K 1–k 4 V B on the global SUV of both tracers The highest positive tratio was found for K 1 receptor binding followed by k 3 cellular internalisation and V B fractional blood volume when using the global 68GaDOTATOC uptake SUV as a target variable Analysis of the 18FFDG data revealed the highest positive tratio for V B followed by k 3 phosphorylation and K 1 influx The comparison of global SUV K 1–k 4 and the FD for 18FFDG and 68GaDOTATOC did not show any statistically significant correlation The only parameter that demonstrated a significant linear correlation between the tracers was V B68GaDOTATOC is a promising tool for evaluation of the expression of SSTR2 in NETs The combination of 18FFDG and 68GaDOTATOC dynamic PET studies provides different information regarding the biological properties of lesions in patients with metastatic NETs in whom 90YDOTATOC therapy is planned While the global 68GaDOTATOC uptake is influenced mostly by K 1 the global 18FFDG uptake is mostly influenced by V B Only patients with enhanced 68GaDOTATOC uptake SUV 50 were referred to 90YDOTATOC therapy
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