The patients will be scanned from the base of the scull to mid thigh by an integrated PET/CT scanner (GE Healthcare DiscoveryTM STE). A standardized CT protocol is used (Smart mA 30-400 mA with a noise index of 18.0 and rotation time of 0.8 s., kV 120, reconstruction thickness of 3.75 mm), followed by a PET examination (recording time is 2.5 min pr. field of view). CT scanning will be done with intravenous contrast medium (Ultravist 370 mg I/ml). The effective dose will be 18-20 mSv from CT and 5-6 mSv from FDG PET. Every patient at the Department of Nuclear Medicine has their height and weight measured before PET/CT and the PET/CT examination must be started in the interval 60 ± 5 min. after injection of FDG. Serum glucose concentration is measured before injection of FDG and must not exceed 8 mmol/L (150 mg/dL) The first 40 patients with a negative FDG-PET/CT will have an extra, late scan (without new contrast and with the same FDG-injection). One half (20 patients) will be scanned after 3 hours and the second half (20 patients) will be scanned 4 hours after the injection of FDG. This is to examine whether there is late focal uptake in some patients due to slow and only slightly increased glucose uptake. If so, the standard time point of scanning will in the remaining patients be at 3 or 4 hours after the injection of FDG in order to optimize the chance of detecting also slow growing tumours and metastases.