Quantitation of Cancer Treatment Response by ¹⁸F-FDG PET/CT: Multicenter Assessment of Measurement Variability

Abstract

The aim of this study was to assess the interobserver variability of quantitative 18 F-FDG PET/CT parameters used in assessments of treatment response across multiple sites and readers. Methods: Paired pre-and posttreatment 18 F-FDG PET/CT images of 30 oncologic patients were distributed to 22 readers across 15 U.S. and international sites. One reader was aware of the full medical history (read reference ) of the patients, whereas the 21 other readers were unaware. The readers selected the single hottest tumor from each study, and made SUV measurements from this target lesion and the liver. Descriptive statistics, percentage changes in the measurements, and their agreements were obtained. Results: The intraclass correlation coefficient for the percentage change in SUV max (%D SUV max ) of the hottest tumor was 0.894 (95% confidence interval [CI], 0.813-0.941), and the individual equivalence coefficient was 1.931 (95% CI, 0.568-6.449) when all reads were included (n 5 638). When only the measurements that selected the same target tumor as the read reference (n 5 486) were included, the intraclass correlation coefficient for the %DSUV max was 0.944 (95% CI, 0.841-0.989), and the individual equivalence coefficient was 20.688 (95% CI, 21.810 to 20.092). The absolute change in SUV mean of liver corrected for lean body mass showed upper and lower limits of agreement (average bias 6 2 SDs) of 0.13 and 20.13 g/mL. Conclusion: The quantitative tumor SUV changes measured across multiple sites and readers show a high correlation. Selection of the same tumor target among readers further increased the degree of correlation. PET/ CT with 18 F-FDG is widely used for assessing response to therapy in clinical trials and clinical practice for patients with cancer. However, data are limited on the concordance of readers using varying software systems in quantitatively determining the treatment response using 18 F-FDG PET/CT. The ability of multiple readers to assign the same treatment response is to some extent dependent on the repeatability of the quantitative data obtained from the images. Despite the numerous factors known to result in variability of SUV measured from 18 F-FDG PET/CT, the interobserver reproducibility of SUV and percentage change in SUV were higher than for measurements of CT size in a single-institution study (1).Our aim was to study the consistency of the major quantitative PET parameters collected across sites and readers, to determine what component of variability there is in target lesion selection and reading software elements. When all readers have identical sets of representative human 18 F-FDG PET/CT digital data available, low to no variability would be expected in the SUV measurements, except for reader selection of targets and software configurations (2,3). Low variability among sites would support quantitative 18 F-FDG PET/CT studies being deployed in a more general manner for treatment response assessment whereas any variability suggests further opportunities for process improvement to minimize va...

Quantitation of cancer treatment response by 2-[18F]FDG PET/CT: multi-center assessment of measurement variability using AUTO-PERCIST™

“…The variance of SUVs could be greater in clinical practice compared to ideal study setting [ 16 ]. In the clinical setting, measurement of SUV max was demonstrated to have high agreement in our previous paper, while the statistically more robust SUL peak showed suboptimal agreement [ 9 ]. We wanted to know whether using uniform software could eliminate the variability associated with the computation differences for SUL peak across multiple vendors and software.…”

“…Sites both with National Cancer Institute Quantitative Imaging Network affiliation and without which did not participate in the previous study with the same data set were recruited by e-mail and conference calls. The dataset was the based on a previous study of reader variability [ 9 ].…”

Interrater Agreement and Reliability of PERCIST and Visual Assessment When Using 18F-FDG-PET/CT for Response Monitoring of Metastatic Breast Cancer

“…This correlates well with our results, although, they did not have a longitudinal study design. Other studies have shown for various types of cancer that raters generally achieved 'moderate agreement' for qualitative visual assessment [25][26][27], and 'almost perfect agreement' for quantitative assessment when measuring the standardized uptake value (SUV) [28][29][30][31][32]. This supports that SUV (from which SUL is derived) is a robust variable to measure; therefore, the discordance in interrater agreement for PERCIST is likely due to the qualitative judgment (detection of new foci or unequivocal progression) of the raters.…”