Demonstration of residual contrast medium in renal parenchyma using computerized tomography.

Residual contrast medium in the renal parenchyma was demonstrated by computerized tomography in 11 patients with renal trauma, inflammatory renal disease, infarction and a large renal cyst. The contrast medium (10 to 100 ml.) was administered intravascularly 30 minutes to 48 hours before the computerized tomography scan. In each patient the scan demonstrated residual contrast medium (either initially or after a second scan with additional contrast enhancement) in a variety of parenchymal zones that frequently appear to be normal with other imaging techniques. After a suitable interval for accumulation of residual contrast medium, computerized tomography appears to provide better visualization of the renal parenchyma than conventional modes of examination. Persistent retention of contrast medium in the renal parenchyma is believed to represent cortical damage.