title: The preliminary study of 18F-FLT micro-PET/CT in predicting radiosensitivity of human nasopharyngeal carcinoma xenografts.
abstract: OBJECTIVE
  The purpose of the preliminary study was to investigate the value of (18)F-FLT micro-PET/CT in predicting radiosensitivity of human nasopharyngeal carcinoma (NPC) xenografts in nude mice models.
  
  
  METHODS
  Twelve BALB/c-nu nude mice were randomly divided into two groups. They were subcutaneously injected with either CNE1 or CNE2 cell suspension. Xenograft volumes were measured after tumor formation. When the tumors reached nearly 10 mm in diameter, they received 15-Gy irradiation. Before and 24 h after irradiation, mice were performed with (18)F-FLT micro-PET/CT. The region of interest (ROI) was manually drawn, and the percent of injected dose per gram of the tumor and muscle in the ROIs was recorded. Tumor-to-muscle ratio (T/M) was calculated and compared with volume changes. Additionally, we also used ten untreated mice as control group.
  
  
  RESULTS
  After irradiation, CNE2 tumors decreased significantly while CNE1 tumors continuously grew and became stable after 1 week. However, in control group, CNE1 and CNE2 tumors continuously enlarged in the observed time. Therefore, we could regard CNE2 group as irradiation responder while CNE1 group as non-responder. In irradiation group, the value of T/M before irradiation (T/M 0) of CNE1 mice was statistically lower than CNE2 mice (1.62 ± 0.38 versus 5.57 ± 1.30; P = 0.004). Besides, T/M decreased significantly in CNE2 group after irradiation (5.57 ± 1.30 versus 3.59 ± 1.06; P < 0.001). By means of a receiver operating characteristic curve, the optimal cut value of T/M 0 and ∆T/M to predict responder was 2.38 and -0.15, respectively (both sensitivity and specificity = 100.0 %).
  
  
  CONCLUSIONS
  (18)F-FLT PET/CT has the potential to predict radiosensitivity in NPC xenografts nude mice models.
authors.affiliation: Department of Nuclear Medicine, Fudan University Shanghai Cancer Center, No. 270, Dong'an Road, Xuhui District, Shanghai, China.
authors.forename: Yujia
authors.initials: Y
authors.lastname: Zheng
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Yang
authors.forename: Yongping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qi
authors.initials: Q
authors.lastname: Shi
authors.forename: Xiao
authors.initials: X
authors.lastname: Bao
authors.forename: Jianping
authors.initials: J
authors.lastname: Zhang
authors.forename: Huiyu
authors.initials: H
authors.lastname: Yuan
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Yao
authors.forename: Chaosu
authors.initials: C
authors.lastname: Hu
authors.forename: Yingjian
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002277:Carcinoma; D045744:Cell Line, Tumor; D015224:Dideoxynucleosides; D006801:Humans; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D064847:Multimodal Imaging / Q000379:methods; D009132:Muscles / Q000000981:diagnostic imaging / Q000528:radiation effects; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D009368:Neoplasm Transplantation; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011836:Radiation Tolerance; D019275:Radiopharmaceuticals; D011897:Random Allocation; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D047368:Tumor Burden / Q000528:radiation effects
chemical_list: D015224:Dideoxynucleosides; D019275:Radiopharmaceuticals; C002854:alovudine