RT Journal Article SR Electronic T1 Repeatability of 18F-FDG Uptake Measurements in Tumors: A Metaanalysis JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 701 OP 708 DO 10.2967/jnumed.111.095299 VO 53 IS 5 A1 Adrianus J. de Langen A1 Andrew Vincent A1 Linda M. Velasquez A1 Harm van Tinteren A1 Ronald Boellaard A1 Lalitha K. Shankar A1 Maarten Boers A1 Egbert F. Smit A1 Sigrid Stroobants A1 Wolfgang A. Weber A1 Otto S. Hoekstra YR 2012 UL http://jnm.snmjournals.org/content/53/5/701.abstract AB PET with the glucose analog 18F-FDG is increasingly used to monitor tumor response to therapy. To use quantitative measurements of tumor 18F-FDG uptake for assessment of tumor response, the repeatability of this quantitative metabolic imaging method needs to be established. Therefore, we determined the repeatability of different standardized uptake value (SUV) measurements using the available data. Methods: A systematic literature search was performed to identify studies addressing 18F-FDG repeatability in malignant tumors. The level of agreement between test and retest values of 2 PET uptake measures, maximum SUV (SUVmax) and mean SUV (SUVmean), was assessed with the coefficient of repeatability using generalized linear mixed-effects models. In addition, the influence of tumor volume on repeatability was assessed. Principal component transformation was used to compare the reproducibility of the 2 different uptake measures. Results: Five cohorts were identified for this metaanalysis. For SUVmax and SUVmean, datasets of 86 and 102 patients, respectively, were available. Percentage repeatability is a function of the level of uptake. SUVmean had the best repeatability characteristics; for serial PET scans, a threshold of a combination of 20% as well as 1.2 SUVmean units was most appropriate. After adjusting for uptake rate, tumor volume had minimal influence on repeatability. Conclusion: SUVmean had better repeatability performance than SUVmax. Both measures showed poor repeatability for lesions with low 18F-FDG uptake. We recommend the evaluation of biologic effects in PET by reporting a combination of minimal relative and absolute changes to account for test–retest variability.