Differences between [¹⁸F]FLT and [¹⁸F]FDG Uptake in PET/CT Imaging in CC Depend on Vaginal Bacteriology

This study aims to investigate if vaginal bacteriology obtained prior to treatment influences the 3'-deoxy-3 18F-fluorothymidine (FLT) [¹⁸F]FLT and 2-deoxy-2-[¹⁸F]fluoro-d-glucose (2-[¹⁸F]FDG) [¹⁸F]FDG parameters in positron emission tomography (PET/CT) in cervical cancer (CC) patients.

Retrospective analysis was performed on 39 women with locally advanced histologically confirmed cervical cancer who underwent dual tracer PET/CT examinations. The [¹⁸F]FLT and [¹⁸F]FDG PET parameters in the primary tumor, including SUVmax, SUVmean, MTV, heterogeneity, before radiotherapy (RT) were analyzed, depending on the bacteriology. The p-values < 0.05 were considered statistically significant.

In the vaginal and/or cervical smears, there were 27 (79.4%) positive results. In seven (20.6%) cases, no opportunistic pathogen growth was observed (No Bacteria Group). In positive bacteriology, eleven (32%) Gram-negative bacilli (Bacteria group 2) and fifteen (44%) Gram-positive bacteria (Bacteria group 1) were detected. Five patients with unknown results were excluded from the analysis. Data analysis shows a statistically significant difference between the SUV_max, and SUV_min values for three independent groups for the [¹⁸F]FLT.

The lowest values of SUV_max and SUV_min for [¹⁸F]FLT are registered in Gram-negative bacteria, higher are in Gram-positive, and the absence of bacteria causes the highest [¹⁸F]FLT values.