Utility of MRI in diagnosis and treatment of acute focal bacterial nephritis with abscess formation in a paediatric patient.

Contrast-enhanced CT is the gold standard for the diagnosis of acute focal bacterial nephritis (AFBN). However, owing to radiation exposure and the possibility of contrast agent-induced side effects, contrast-enhanced CT is not always recommended for children. A paediatric patient presenting with a 1-week history of fever was admitted to our hospital. After a urine culture detected Escherichia coli, antimicrobials were administered; however, the fever had not resolved by the third day of hospitalisation. Renal diffusion-weighted MRI was performed and showed multiple wedge-shaped areas of high signal intensity in the right kidney. Additionally, the same site showed an area of low signal intensity in the apparent diffusion coefficient, and a diagnosis of AFBN with abscess was made. A chronic-phase technetium-99m-labelled dimercaptosuccinic acid renal scintigraphy was performed, but there was no renal scarring. MRI may be a more suitable tool for diagnosing AFBN given no radiation exposure.