Davis JC, et al. - Physicians designed this study to ascertain the relationship of ¹⁸F-FDG uptake in the primary tumor at diagnosis, during therapy, and after therapy with a histologic response and event-free survival in pediatric and young adult patients with osteosarcoma (OS). Metabolic predictors of a histologic response in OS were SUV_max on routine images at 5 or 10 wk and percentage change in SUV_max from baseline to week 10. These findings appeared to be useful in the early identification of patients who were responding poorly to therapy and could benefit from a change in treatment.