Figure 6.

A 13-year-old boy with metastatic osteosarcoma. Compare the single breath-hold staging chest CT (a) with the CT component of the PET-CT during quiet respiration (b) at the same window level. Two small metastases are shown in both images. The first (red arrows) is visible on both scans, but the second (circled) is more difficult to discern on the PET-CT due to poor lung expansion, breathing artefact and noise. A further metastasis (arrow) in the same patient (c) does not show any FDG activity (d). This is likely due to the small size of the metastasis and limited PET resolution. FDG, fluorodeoxyglucose; PET, positron emission tomography.