Acute MRI changes in infectious discitis: report on two cases.

Previous reports suggest that MRI changes should be seen within 48h of symptoms arising. We report on two patients with proven discitis at the L5/S1 disc. MRI performed within 60h of the onset of symptoms did not demonstrate evidence of infection and therefore did not confirm the diagnosis of discitis. The reliability of early MRI to confirm infective discitis is questionable. The cases we report on did not display any of the typical changes of discitis on MRI within the first 48h after the onset of symptoms. Absence of typical infective changes on MRI does not necessarily exclude an infection within the disc space.