High-resolution computed tomography of the normal rat nephrogram.

This study describes a unique, film-recorded computed tomography (CT) system and its use in studying contrast flow between anatomic compartments of the rat kidney. The CT apparatus, composed of a microfocal spot tube, rotating animal carrier, film-cassette translator, and control electronics, was used to expose "sinograms" of 3:1 magnification through the kidneys of normal rats prior to and 2, 15, 30, 60, and 120 minutes after intravenous contrast injection. Microdensitometry and computer reconstruction resulted in CT images representing 1-mm thick coronal sections with lateral resolution of 150 micron. With this novel technique of ultrahigh-resolution CT, temporal alterations in absorption coefficient of cortical and medullary nephrographic components were depicted for contrast flow study in our small animal model.