PET/CT is a new imaging tool that combines two scan techniques in one examination– a PET scan and a CT scan. PET/CT is mainly used for diagnosis, staging or restaging malignant disease, metastases and evaluation of treatment response. It may also be used to differentiate dementia verses Alzheimer’s disease. The two procedures together provide information regarding location, nature of and the extent of the lesion. In other words it answers questions like: Where is the tumour, the size of the tumour, is it malignant, benign or due to inflammatory change, and has the cancer spread?