Figure 5. Relationship between lesion size and tumour-to-background ratio (T/B ratio) obtained by ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) (a) and FDG dual-head positron coincidence determination gamma camera detection (PCD) (b). No correlation is observed between lesion size and T/B ratio by either FDG PCD or FDG PET.