Variation in average tumor response in population. (Left and middle) For each ROIpeak definition, tumor response was averaged over all tumors, resulting in population average response (mean response, dashed line). SUVmax response is also shown. (Right) Overall variation in population average response and variation associated with changing size, location, and shape of ROIpeak. Boxes represent SD, whiskers show range, and solid line depicts median. Variation in population average response is extremely small (~2%).