Test–Retest Reproducibility of 18F-FDG PET/CT Uptake in Cancer Patients Within a Qualified and Calibrated Local Network

摘要

Calibration and reproducibility of quantitative ¹⁸F-FDG PET measures are essential for adopting integral ¹⁸F-FDG PET/CT biomarkers and response measures in multicenter clinical trials. We implemented a multicenter qualification process using National Institute of Standards and Technology–traceable reference sources for scanners and dose calibrators, and similar patient and imaging protocols. We then assessed SUV in patient test–retest studies. >Methods: Five ¹⁸F-FDG PET/CT scanners from 4 institutions (2 in a National Cancer Institute–designated Comprehensive Cancer Center, 3 in a community-based network) were qualified for study use. Patients were scanned twice within 15 d, on the same scanner (n = 10); different but same model scanners within an institution (n = 2); or different model scanners at different institutions (n = 11). SUVmax was recorded for lesions, and SUVmean for normal liver uptake. Linear mixed models with random intercept were fitted to evaluate test–retest differences in multiple lesions per patient and to estimate the concordance correlation coefficient. Bland–Altman plots and repeatability coefficients were also produced. >Results: In total, 162 lesions (82 bone, 80 soft tissue) were assessed in patients with breast cancer (n = 17) or other cancers (n = 6). Repeat scans within the same institution, using the same scanner or 2 scanners of the same model, had an average difference in SUVmax of 8% (95% confidence interval, 6%–10%). For test–retest on different scanners at different sites, the average difference in lesion SUVmax was 18% (95% confidence interval, 13%–24%). Normal liver uptake (SUVmean) showed an average difference of 5% (95% confidence interval, 3%–10%) for the same scanner model or institution and 6% (95% confidence interval, 3%–11%) for different scanners from different institutions. Protocol adherence was good; the median difference in injection-to-acquisition time was 2 min (range, 0–11 min). Test–retest SUVmax variability was not explained by available information on protocol deviations or patient or lesion characteristics. >Conclusion: ¹⁸F-FDG PET/CT scanner qualification and calibration can yield highly reproducible test–retest tumor SUV measurements. Our data support use of different qualified scanners of the same model for serial studies. Test–retest differences from different scanner models were greater; more resolution-dependent harmonization of scanner protocols and reconstruction algorithms may be capable of reducing these differences to values closer to same-scanner results.