Purpose: The aim of this study was to investigate the relationship between whole-tumor CT perfusion and FDG PET/CT parameters in non-small cell lung cancer (NSCLC).
Methods: Twenty-five patients with NSCLC were prospectively included. CT perfusion parameters calculated were blood flow (BF), blood volume (BV), mean transit time, and peak enhancement intensity. SUVmax, SUVpeak, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were evaluated for PET/CT. Tumor diameter and volume were measured, and lesions were divided according to maximum axial diameter in more than 3 cm and 3 cm or less. The correlations between CT perfusion and PET/CT parameters were assessed in all tumors, as well as according to tumor diameter and volume.
Results: Lesion diameter and volume showed a negative correlation with BF and BV (r = -0.78, -0.78, -0.57, -0.48, respectively) and a positive correlation with mean transit time (r = 0.55, 0.65, respectively). The negative correlation between BF and lesion diameter and volume was confirmed in the subgroup of lesions of more than 3 cm (r = -0.68, -0.68, respectively). A positive correlation between SUVmax, SUVpeak, SUVmean, and lesion volume was observed (r = 0.50, 0.50, 0.46, respectively) and confirmed in lesions 3 cm or less (r = 0.81, 0.79, 0.78, respectively). Metabolic tumor volume and TLG showed a positive correlation with lesion diameter and volume in the overall population (r = 0.93, 0.87, 0.88, 0.90, respectively) and in lesions of more than 3 cm (r = 0.89, 0.84, 0.84, 0.79, respectively). Blood flow and BV showed a negative correlation with MTV and TLG (r = -0.77, -0.74, and -0.58, -0.48, respectively) in the overall population and with MTV in lesions of more than 3 cm (r = -0.69, -0.62, respectively).
Conclusions: Perfusion and metabolic parameters seem to depend on tumor size. The bigger the tumor, the lower the BF and the BV and, conversely, the higher the SUVpeak, MTV, and TLG. This information would be useful in the clinical setting when diagnosing or treating NSCLC, especially with novel therapies and/or for radiation treatment modulation.