DELAYED CT FINDINGS IN ACUTE RENAL INFECTION

The computed tomography (CT) findings in twelve patients with acute re nal infection examined immediately and 3h after i.v. contrast medium a re reported. Three patients also had delayed scans at 6 h. Three main features were observed on the delayed scans: 1 a delayed nephrogram wi th streaky, wedge shaped or round high density areas. The areas of hig h density were at the same sites of the inhomogeneous areas of reduced density on the early scans; 2 focal contrast medium staining or a rim of increased density around abscesses; 3 focal areas of increased den sity at sites distant from the low density areas seen on the early sca ns. It is postulated that the delayed areas of increased density repla ce early areas of reduced density caused by ischemia due to vasospasm and/or compressing oedema of the vascular bed or by tubular obstructio n. Delayed CT appears to be useful because it improves diagnostic conf idence and gives a more exact evaluation of the extent of infection.