Noninvasive evaluation of metabolic tumor volume in lewis lung carcinoma tumor-bearing C57BL/6 mice with micro-PET and the radiotracers 18F-alfatide and 18F-FDG: A comparative analysis

Abstract

Purpose: To explore the value of a new simple lyophilized kit for labeling PRGD22peptide (18F-ALF-NOTA-PRGD2, denoted as 18F-alfatide) in the determination of metabolic tumor volume (MTV) with micro-PET in lewis lung carcinoma (LLC) tumor-bearing C57BL/6 mice verified by pathologic examination and compared with those using 18F-fluorodeoxyglucose (FDG) PET. Methods: All LLC tumor-bearing C57BL/6 mice underwent two attenuation-corrected whole-body micro-PET scans with the radiotracers 18F-alfatide and 18F-FDG within two days. 18F-alfa-tide metabolic tumor volume (VRGD) and 18F-FDG metabolic tumor volume (VFDG) were manually delineated slice by slice on PET images. Pathologic tumor volume (VPath) was measured in vitro after the xenografts were removed. Results: A total of 37 mice with NSCLC xenografts were enrolled and 33 of them underwent 18F-alfa-tide PET, and 35 of them underwent 18F-FDG PET and all underwent pathological examination. The mean ± standard deviation of VPath, VRGD, and VFDGwere 0.59±0.32 cm3(range, 0.13∼1.64 cm3), 0.61 ±0.37 cm3(range, 0.15∼1.86 cm3), and 1.24±0.53 cm3(range, 0.17∼2.20 cm3), respectively. VPathvs. VRGD, VPathvs. VFDG, and VRGDvs. VFDGcomparisons were t = -0.145, P = 0.885, t = -6.239, P<0.001, and t = -5.661, P<0.001, respectively. No significant difference was found between VPathand VRGD.VFDGwas muchlarger than VRGDand VPath. VRGDseemed more approximate to the pathologic gross tumor volume. Furthermore, VPathwas more strongly correlated with VRGD(R = 0.964, P<0.001) than with VFDG(R = 0.584, P<0.001). Conclusions: 18F-alfatide PET provided a better estimation of gross tumor volume than 18F-FDG PET in LLC tumor-bearing C57BL/6 mice. Copyright: