TY - JOUR T1 - Comparison of Sigma-Ligands and Metabolic PET Tracers for Differentiating Tumor from Inflammation JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 150 LP - 154 VL - 47 IS - 1 AU - Aren van Waarde AU - Pieter L. Jager AU - Kiichi Ishiwata AU - Rudi A. Dierckx AU - Philip H. Elsinga Y1 - 2006/01/01 UR - http://jnm.snmjournals.org/content/47/1/150.abstract N2 - Novel radiopharmaceuticals for the detection of tumors and their metastases may be of clinical interest if they are more tumor selective than 18F-FDG. Increased glucose metabolism of inflammatory tissues is the main source of false-positive 18F-FDG PET findings in oncology. Methods: We compared the biodistribution of 4 PET tracers (2 σ-receptor ligands, 11C-choline, and 11C-methionine) with previously published biodistribution data of 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) and of 18F-FDG in the same animal model. The model consisted of male Wistar rats that bore tumors (C6 rat glioma in the right shoulder) and also had sterile inflammation in the left calf muscle (induced by injection of 0.1 mL of turpentine). Twenty-four hours after turpentine injection, the rats received an intravenous bolus of PET tracer (approximately 30 MBq in the case of 18F and 74 MBq for 11C). Results: 18F-FDG showed the highest tumor-to-muscle ratio of all radiopharmaceuticals (13.2 ± 3.0, mean ± SD), followed at a large distance by the σ-1 ligand 11C-SA4503 (5.1 ± 1.7), 18F-FLT (3.8 ± 1.3), the non–subtype-selective σ-ligand 18F-FE-SA5845 (3.3 ± 1.5), 11C-choline (3.1 ± 0.4), and 11C-methionine (2.8 ± 0.3). σ-Ligands and 18F-FLT were relatively tumor selective (18F-FE-SA5845, greater than 30-fold; 11C-SA4503 and 18F-FLT, greater than 10-fold). The tumor selectivity of 11C-methionine was only slightly better than that of 18F-FDG. 11C-Choline showed equal uptake in tumor and inflammation. All tracers were avidly taken up by proliferative tissue (small intestine, bone marrow). High physiologic uptake of some compounds was observed in brain, heart, lung, pancreas, spleen, and salivary gland. Conclusion: σ-Ligands and 18F-FLT were more tumor selective than 18F-FDG, 11C-choline, or 11C-methionine in our animal model. However, these novel radiopharmaceuticals were less sensitive than were the established oncologic tracers. ER -