[18F]FLT-PET and [18F]FDG-PET in the evaluation of radiotherapy for laryngeal cancer
Received 4 June 2009; received in revised form 10 July 2009; accepted 10 July 2009. published online 19 August 2009.
Summary
The evaluation of response to radiotherapy in patients with laryngeal cancer is a challenge because of the difficulty to differentiate between post-therapy changes and recurrent or residual tumor. Positron emission tomography is a non-invasive imaging tool that may be helpful in this differentiation. In this study, [18F]-fluoro-3′-deoxy-l-thymidine ([18F]FLT), a proliferation tracer is compared with 2-[18F]-fluoro-2-deoxy-d-glucose ([18F]FDG).
Patients with primary laryngeal cancer, scheduled to undergo radiotherapy were included in this study. Patients underwent both [18F]FLT-PET and [18F]FDG-PET shortly before radiotherapy. Ten patients underwent [18F]FLT-PET and [18F]FDG-PET 2–3months after radiotherapy. Scans were analyzed visually for areas of increased tracer uptake. The standardized uptake value (SUV) was measured as a semi-quantitative value of tracer uptake.
Fourteen patients, all male, were included in this study. Both [18F]FLT-PET and [18F]FDG-PET showed increased tracer uptake in 12 out of 14 patients (86%). [18F]FDG uptake was significantly higher than [18F]FLT uptake (SUVmax: 4.5 vs. 2.4 (P=0.002); SUVmean: 3.4 vs. 1.9 (P=0.002)). After radiotherapy, 3 patients had histologically proven residual or recurrent laryngeal cancer. [18F]FDG was true positive in 2 out of 3 patients, whereas [18F]FLT showed increased tracer uptake in only one. Of the remaining 7 patients, [18F]FLT was true negative in all, whereas [18F]FDG showed increased uptake in one (false positive).
[18F]FLT-PET is feasible in visualizing laryngeal cancer and its evaluation of treatment. The overall uptake of this tracer is significantly lower as compared with [18F]FDG, but tumor to background ratios are comparable.
aDepartment of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
bDepartment of Surgical Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
cDepartment of Pathology and Laboratory Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
dDepartment of Otorhinolaryngology – Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
Corresponding author. Address: Department of Surgical Oncology, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9713 GZ Groningen, Groningen, The Netherlands. Tel.: +31 50 3612303; fax: +31 50 3614873.
1 Address: Department of Surgical Oncology, University Medical Center Groningen, P.O. Box 30.001, 9700 RB Groningen, Groningen, The Netherlands. Tel.: +31 50 3616161; fax: +31 50 3614873.
ABSTRACT