Positron emission tomography with [18F]-fluorodeoxyglucose provides functional and anatomic information by visualising the uptake of radiolabelled glucose in tumour and inflammatory cells. We report delayed diagnosis of necrosis of the gastric fundus after blunt abdominal trauma in a 73-year-old man. After a car accident with head-on collision, the patient was stabilised in our emergency room. His femur was treated by internal fixation, his ellbow was stabilised by a fixateur externe. During surgery his status deteriorated. The patient was in need of high dosage of inotrops during the following days. He had a biventricular pacemaker implanted because of ischemic myocardiopathy, and he suffered from renal insufficiency. Over the next days, his haemodynamics improved. A central venous line had to be removed because of ensuing septic fever. The patient complained of upper abdominal pain and nausea. A sonography and computer tomography without contrast medium were performed with negative result. Because of contamination of the central venous line with Staphylococcus epidermidis the pacemaker was evaluated for infection by transoesophageal echocardiography, again without any findings. Because of ongoing fever and positive inflammatory markers a positron emission tomography was indicated, as a contrast examination and a magnetic resonance examination were not feasible because of the renal insufficiency and the pacemaker, respectively. Prophylactic removal of the pacemaker would have been a substantial risk for the patient due to his underlying myocardiopathy. Positron emission tomography showed an increased tracer uptake in the gastric fundus, which turned out to be necrotic by endoscopy. A laparoscopic resection followed, and drainage of an abscess, which had evolved subsequently between stomach and spleen stopped the inflammatory process. This case report demonstrates that positron emission tomography may be an alternative to computer tomography with contrast medium and magnetic resonance imaging to detect an inflammatory process in patients with pre-existing disease.