Treatment Monitoring by 18F-FDG PET/CT in Patients with Sarcomas: Interobserver Variability of Quantitative Parameters in Treatment-Induced Changes in Histopathologically Responding and Nonresponding Tumors

摘要

Measurements of tumor glucose use by ¹⁸F-FDG PET need to be standardized within and across institutions. Various parameters are used for measuring changes in tumor glucose metabolic activity with ¹⁸F-FDG PET in response to cancer treatments. However, it is unknown which of these provide the lowest variability between observers. Knowledge of the interobserver variability of quantitative parameters is important in sarcomas as these tumors are frequently large and demonstrate heterogeneous ¹⁸F-FDG uptake.MethodsA total of 33 patients (16 men, 17 women; mean age, 47 ± 18 y) with high-grade sarcomas underwent ¹⁸F-FDG PET/CT scans before and after neoadjuvant chemotherapy. Two independent investigators measured the following parameters on the pretreatment and posttreatment scans: maximum standardized uptake value (SUVmax), peak SUV (SUVpeak), mean SUV (SUVmean), SUVmean in an automatically defined volume (SUVauto), and tumor-to-background ratio (TBR). The variability of the different parameters was compared by concordance correlation coefficient (CCC), variability effect coefficient, and Bland–Altman plots.