Proliferation rates assessed by [18F]-fluorothymidine (FLT) PET is low and does not reflect glucose metabolism assessed by [18F]-fluorodeoxyglucose (FDG) PET in paragangliomas.

Friday, November 08, 2013 — Poster Session III
10:00 a.m. – 12:00 p.m.	FAES Academic Center (Upper-Level Terrace)	NICHD	CLIN-2

Authors

EM Blanchet
C Millo
V Martucci
M Merino
P Herscovitch
K Pacak

Abstract

Objectives: This pilot study aimed to image cellular proliferation in paragangliomas (PGLs) using [18F]-fluorothymidine (FLT) positron emission tomography (PET), to evaluate it for prediction of tumor aggressiveness and to compare it with [18F]-fluorodeoxyglucose (FDG) PET. Material and Methods: Twelve patients with PGLs (7 metastatic and 5 non-metastatic) were scanned with FDG and FLT. Uptake was assessed at a lesion level, visually and quantitatively by maximum standard uptake values (SUVmax) for both tracers. FLT uptake was compared to risk factors known to be linked with aggressiveness in PGLs (SDHB-mutated status, lesion size, dopaminergic phenotype) and with FDG uptake. Results: In 12 patients, 77 lesions were assessed. All lesions had low FLT uptake (median SUVmax of 2.25 and range of [0.7-4.5]). There was no apparent superiority of FLT uptake in lesions believed to be aggressive, and most of the lesions showed a mismatch, with high FDG uptake (median SUVmax of 10.8 and range of [1.1-79.0]) contrasting with low FLT uptake. Conclusions: The cellular proliferation rate was very low in PGL, including those with aggressiveness criteria and with high FDG uptake. These findings provide a new insight into PGL biological behavior and suggest not to use antiproliferative agents for treatment of these tumors.