RT Journal Article
SR Electronic
T1 Selectivity of <sup>18</sup>F-FLT and <sup>18</sup>F-FDG for Differentiating Tumor from Inflammation in a Rodent Model
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 695
OP 700
VO 45
IS 4
A1 van Waarde, Aren
A1 Cobben, David C.P.
A1 Suurmeijer, Albert J.H.
A1 Maas, Bram
A1 Vaalburg, Willem
A1 de Vries, Erik F.J.
A1 Jager, Pieter L.
A1 Hoekstra, Harald J.
A1 Elsinga, Philip H.
YR 2004
UL http://jnm.snmjournals.org/content/45/4/695.abstract
AB Increased glucose metabolism of inflammatory tissues is the main source of false-positive 18F-FDG PET findings in oncology. It has been suggested that radiolabeled nucleosides might be more tumor specific. Methods: To test this hypothesis, we compared the biodistribution of 3′-deoxy-3′-18F-fluorothymidine (FLT) and 18F-FDG in 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 (30 MBq) of either 18F-FLT (n = 5) or 18F-FDG (n = 5). Pretreatment of the animals with thymidine phosphorylase (&gt;1,000 U/kg, intravenously) before injection of 18F-FLT proved to be necessary to reduce the serum levels of endogenous thymidine and achieve satisfactory tumor uptake of radioactivity. Results: Tumor-to-muscle ratios of 18F-FDG at 2 h after injection (13.2 ± 3.0) were higher than those of 18F-FLT (3.8 ± 1.3). 18F-FDG showed high physiologic uptake in brain and heart, whereas 18F-FLT was avidly taken up by bone marrow. 18F-FDG accumulated in the inflamed muscle, with 4.8 ± 1.2 times higher uptake in the affected thigh than in the contralateral healthy thigh, in contrast to 18F-FLT, for which this ratio was not significantly different from unity (1.3 ± 0.4). Conclusion: In 18F-FDG PET images, both tumor and inflammation were visible, but 18F-FLT PET showed only the tumor. Thus, the hypothesis that 18F-FLT has a higher tumor specificity was confirmed in our animal model.