Interobserver and Intraobserver Variability among Measurements of FDG PET/CT Parameters in Pulmonary Tumors

Abstract

Background: 18F-fluorodeoxyglucose (FDG) positronemission tomography computed tomography (PET/CT)provides information about metabolic and morphologicstatus of malignancies. Tumor size and standardized uptakevalue (SUV) measurements are crucial for cancer treatmentmonitoring.Aims: The purpose of our study was to assess the variabilityof these measurements performed by observers evaluatinglung tumors.Study Design: Retrospective cross-sectional study.Methods: FDG PET/CT images of 97 patients with pulmonarytumors were independently evaluated by two experiencednuclear medicine physicians. Primary tumorsize (UDCT), maximum SUV (SUVmax), mean SUV(SUVmean) and maximum SUV normalized to liver meanSUV (SUVnliv max) were measured by each observer attwo different times with an interval of at least 2 weeks. Interobserverand intraobserver variabilities of measurementswere evaluated through statistical methods.Results: Size of the lesions varied from 0.81 to 13.6 cm(mean 4.29±2.24 cm). Very good agreement was shownwith correlation, Bland-Altman and regression analysis forall measured PET/CT parameters. In the interobserver andintraobserver variability analysis, the Pearson correlationcoefficients were greater than 0.96 and 0.98, respectively.Conclusion: Semi-quantitative measurements of pulmonarytumors were highly reproducible when determined byexperienced physicians with clinically available softwarefor routine FDG PET/CT evaluation. Consistency may beimproved if the same observer performs serial measurementsfor any one patient.