Reliability of standardized uptake value normalized to lean body mass using the liver as a reference organ, in contrast-enhanced 18F-FDG PET/CT imaging

To evaluate the reliability of standardized uptake value (SUV) normalized to lean body mass for maximum (SULmax) and mean values (SULmean) as well as maximum SUV values (SUVmax) in contrast-enhanced 18F-FDG PET/CT by assessment of inter-reader agreement, using the liver as a reference organ. 272 images of baseline PET/CT scans were analyzed. A volume of interest (VOI) of 30-mm in diameter was placed by two independent readers in the right liver lobe to measure the parameters. An analysis was performed for the variance, intra-class correlation coefficient (ICC), and Bland-Altman plots. For Reader 1, the SUVmax ranging from 1.33 to 5.94 (3.20 ± 0.69), SULmean ranging from 0.84 to 3.46 (1.90 ± 0.40) and SULmax ranging from 1.18 to 4.07 (2.38 ± 0.50), were obtained; for Reader 2 the SUVmax ranging from 1.47 to 5.43 (3.20 ± 0.70), SULmean ranging from 0.84 to 3.45 (1.90 ± 0.40), and SULmax ranging from 1.18 to 4.48 (2.38 ± 0.50), were obtained. The coefficient of variance for SUVmax, SULmean, and SULmax, were 21.9%, 21.1%, and 20.8%, respectively, having no significant differences between Reader 1 and Reader 2. The ICC of the two readers for SUVmax, SULmean and SULmax were 0.975, 0.982 and 0.977 (95% CI of 0.97, 0.98 and 0.97; p < .001) respectively. Bland-Altman plots revealed that SUVmax gave the best agreement with 97.1% of measurements falling within 2SD. There is an excellent inter-reader agreement for liver SUVmax, SULmean and SULmax, and the best reliability of measurements achieved with SULmax in contrast-enhanced PET/CT scans. •Inter-reader agreement was evaluated for contrast-enhanced PET/CT parameters using the liver as a reference organ.•Excellent inter-reader agreements were achieved for SUVmax, SULmean and SULmax.•A higher range of SULmax values (1.18 - 4.07) was observed in contrast-enhanced PET/CT scans.•Liver SULmax gave the best agreement and precision and should be clinically utilized for oncology treatment monitoring.