Abstract:
Objective This study aims to evaluate early the efficacy of 18F-FLT and 18F-FDG PET/CT imaging systems in assessing the tumor response of radiotherapy for pulmonary adenocarcinoma.
Methods A total of 40 A549 xenografts with human pulmonary adenocarcinoma were treated with different dosages (0, 5, 10, 15, and 30 Gy) of X-ray irradiation (radiotherapy). Changes in tumor volume during the entire experimental period were observed. 18F-FDG and 18F-FLT PET/CT imaging systems were employed before radiotherapy and at 3 d, 1 week, 2 weeks, and 4 weeks after radiotherapy. SUVmax and T/N were analyzed. Immunohistochemical analysis of the xenografts was conducted to detect the proliferation expression of Ki-67. The T/N values of the 18F-FDG and 18F-FLT PET/CT imaging systems and the corresponding indexes of Ki-67 before and after radiotherapy were compared.
Results Both imaging systems identified the xenografts before irradiation and distinguished malignancy according to the T/N values (T/N>1.5) of xenografts. The positive expression rates of Ki-67 decreased as the radiation time was prolonged and as the dosage was increased. The T/N values of the xenografts in the 18F-FDG and 18F-FLT PET/CT images of each time point were correlated with the positive expression rates of Ki-67. The correlation in 18F-FLT PET/CT imaging was better than that in 18F-FDG imaging.
Conclusion Changes in 18F-FLT uptake reflected proliferation. 18F-FLT PET/CT imaging can be used for the early evaluation of radiotherapy for pulmonary adenocarcinoma.
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