Renal perfusion and neutrophil-mediated inflammation will be assessed in the kidney in sepsis patients with acute kidney injury using positron emission tomography. For marked water will be used for renal perfusion and a newly developed PET tracer molecule (11C-GW457427) with specific binding to neutrophil elastase which provides a measure of the amount of infiltrating neutrophils in the renal parenchyma for inflammation. The study is performed in a PET-CT camera where anatomical imaging takes place at the same time as the PET examinations.