Interobserver and Intraobserver Variability of Standardized Uptake Value Measurements in Non–small-cell Lung Cancer

Objectives To assess interobserver and intraobserver variabilities in measuring the maximal standardized uptake value (SUV) of non–small-cell lung cancer. Methods Positron emission tomography-computed tomography examinations of 20 consecutive patients referred for initial evaluation of newly diagnosed non–small-cell lung cancer were retrospectively reviewed by 5 experienced positron emission tomography-computed tomography readers, who independently measured the maximal SUV/body weight of the primary tumors. Interobserver and intraobserver variabilities were assessed by using 4 statistical methods: correlation, regression analysis, Bland-Altman analysis, and analysis of variance. The SUV measurements derived in the study were compared with the SUV measurements documented in the original reports using correlation and regression analysis. The percentages of tumors whose retrospective SUV measurements were more than 20% different and more than 25% different from those in the original report were assessed. Results Both interobserver and intraobserver SUV measurements were highly reproducible. Pearson correlation coefficients were greater than 0.95 and 0.94, respectively. Good interobserver and intraobserver agreement was shown with regression analysis (F test P value >0.05), the Bland-Altman analysis, and analysis of variance (F test P value >0.95). The mean original SUV was much less than the mean study SUV (P<0.05). The study SUV differed from the SUV of the original report by more than 20% in 50% of the tumors, and by more than 25% in 45% of the tumors. Conclusions There was excellent interobserver and intraobserver agreement in SUVs measured in the study environment but poor agreement between study SUVs and those documented in original reports, which can affect treatment decisions substantially.