A preliminary study of a novel image analysis methodology for quantification of lung tumor response and lung inflammation post-radiation therapy on FDG-PET/CT

Objectives To assess novel image analysis software to quantify tumor response and lung inflammation after radiation therapy (XRT) on FDG-PET/CT.

Methods 20 patients with stage III NSCLC with pre- and post-XRT FDG-PET/CT were retrospectively identified. Tumor metabolically active volume (MAV) and uncorrected and partial volume corrected (PVC) SUVmean and metabolic volumetric product mean (MVPmean=MAVxSUVmean) were then quantified using ROVER software (ABX GmbH, Germany). Lung inflammation was calculated by placing ROIs around each lung to measure total lung volume and MVP and then subtracting tumor measurements.

Results Tumor Response: Average MAV decrease post-XRT was 26.49±10.32cc (p=0.02; 95%CI 4.89-48.08cc), average SUVmax decrease was 9.08±1.07 (p< 0.01; 95%CI 6.85-11.32), average uncorrected SUVmean decrease was 5.39±0.71 (p< 0.01; 95%CI 3.90-6.89), average PVC SUVmean decrease was 9.25±1.26 (p< 0.01; 95%CI 6.62-11.87), average uncorrected MVPmean decrease was 366.6±108.8cc (p< 0.01; 95%CI 139.0-594.2cc), and average PVC MVPmean decrease was 556.2±155.6cc (p< 0.01; 230.5-881.8cc). Inflammation: XRT lung: Average uncorrected SUVmean increase was 0.181±0.088 (p=0.05; 95%CI 0.002-0.364), average PVC SUVmean increase was 0.329±0.111 (p=0.01; 95%CI 0.097-0.561), average PVC MVPmean increase was 289.1±101.8cc (p=0.01; 95%CI 76.1-502.2cc), and no change in average uncorrected MVPmean was observed. Contralateral (control) lung: No change in these 4 parameters was seen.

Conclusions It is feasible to quantify tumor response and lung inflammation on FDG-PET/CT after XRT using novel analysis approaches. All tumor measurements showed decreased activity post-XRT, indicating tumor response, where PVC measurements revealed the greatest degrees of response