Abstract
Background: To determine the optimum conditions for diagnosis of nasopharyngeal carcinoma, we established VX2 rabbit model to delineate gross target volume (GTV) in different imaging methods. Methods: The orthotopic nasopharyngeal carcinoma (NPC) was established in sixteen New Zealand rabbits. After 7-days inoculation, the rabbits were examined by CT scanning and then sacrificed for pathological examination. To achieve the best delineation, different GTVs of CT, MRI, (18)F-FDG PET/CT, and (18)F-FLT PET/CT images were correlated with pathological GTV (GTVp). Results: We found 45% and 60% of the maximum standardized uptake value (SUV(max)) as the optimal SUV threshold for the target volume of NPC in (18)F-FDG PET/CT and (18)F-FLT PET/CT images, respectively (GTV(FDG45%) and GTV(FLT60%)). Moreover, the GTV(MRI) and GTV(CT) were significantly higher than the GTVp (P ≤ 0.05), while the GTV(FDG45%) and especially GTV(FLT60%) were similar to the GTVp (R = 0.892 and R = 0.902, respectively; P ≤ 0.001). Conclusions: Notably, the results suggested that (18)F-FLT PET/CT could reflect the tumor boundaries more accurately than (18)F-FDG PET/CT, MRI and CT, which makes (18)F-FLT PET-CT more advantageous for the clinical delineation of the target volume in NPC.