Creatinine and cystatine C serum levels will be collected one hour before CT scan and at day 2, 4 and 10. The T0 value will be the value measured before the CT-scan and not the baseline admission value in order to correct for differential hydratation due to different waiting time and hydratation before tomography. Serum Creatinine and Cystatine C will be measured by the Jaffe method, and by a nephelometric assay respectively.