Upper urinary tract infection: the current role of CT, ultrasound, and MRI.

This article reviewed some of the fundamental concepts in renal inflammatory disease. The difficulties in present terminology were reviewed and our approach discussed. The pathological underpinning of the acute-subacute infections were contrasted with those seen in the granulomatous diseases. The importance of CT in separating emphysematous pyelonephritis from emphysematous pyelitis and perinephric emphysema was stressed. Although ultrasound has been used in the past and is still of value in select situations, we prefer CT for assessment of renal infection. CT examinations show whether the disease is focal or diffuse, whether air is present, whether there is perinephric or pararenal extension, whether an abscess is present, and when the ideal time is for intervention. In severe renal infection in the adult, CT has shown the development of renal scars, perinephric extension, and the spontaneous drainage of Staphylococcus abscesses into nearby calyces.