Comparison of semiquantitative metabolic parameters of the primary tumor obtained in PET/CT with 18F-FDG and 18F-FLT in patients with cervical cancer

Abstract

Aim The aim of the study was to compare semiquantitative metabolic parameters of primary tumor assessed in vivo in 18F-FDG- and 18F-FLT in cervical cancer patients.

Material & Methods 39 patients with histologically confirmed cervical cancer underwent PET/CT scans acquired on separate days 60 min after i. v. injection of 364 ± 75 MBq of 18F-FDG and 259 ± 40 MBq of 18F-FLT. The reconstructed PET images were evaluated using a dedicated workstation for primary tumor semiquantitative parameters: SUVmax, MTV, TLG (for 18F-FLT-TLP) and heterogeneity (AUC-CSH). Wilcoxon-Mann-Whitney test and ROC curves were used for statistical analysis. Based on data from the local cancer registry and 3y- to -5y follow up patients were divided into 2 groups with regard to prognosis. Also differences between histopathological type and FIGO classification in two tracers were assessed.

Results Depending on PET/CT results, patients were divided into 3 groups: group 1 with disease limited only to the cervix, group 2 with disease limited to the cervix and iliac lymph nodes, and group 3 with disseminated disease. Statistically significant differences were found between keratinizing and non-keratinizing SCC in SUVmax (p = 0.03) and AUC-CSH (p = 0.04) only in 18F-FLT-PET/CT. Following cut-off values for nodal involvement in SUVmax, MTV, TLG/TLP and AUC-CSH were calculated using ROC curves: 13.5, 39.22, 255.94, 0.59 respectively for 18F-FDG and 12.1, 37.59, 140.01, 0.46 respectively for 18F-FLT. Higher values in both tracers in MTV and TLG/TLP were found in a group with worse prognosis.

Conclusion This preliminary study suggests that higher values in MTV and TLG/TLP in both tracers might be associated with worse outcome in cervical cancer patients.