What do the renal veins look like on a cavogram?
Usually, the renal veins are not opacified by contrast material injected into the IVC because the opacified blood in the cava flows preferentially back to the right atrium. The location of the renal veins can be determined, however, because unopacified blood from the renal veins mixes with and dilutes opacified blood in the cava. The location of the renal veins can be inferred from inflow defects in the stream of contrast material in the IVC. If there is doubt about their locations, a selective injection of the renal veins may be performed.