Evaluation of the renal outline by excretory urography.

Tomograms and oblique radiographs were compared in 172 adult patients undergoing routine urography to assess the degree of renal outline visualized and to determine the best midpoint for nephrotomography. Tomograms proved better for demonstrating the renal outline (66.3% of patients demonstrating 78.4% of the renal circumference) than oblique views (only 23.2% of patients demonstrating 65.5% of the renal circumference). The combination of tomograms and oblique radiographs proved best, demonstrating 96.5% of the renal outline. Colon cleanliness was a significant factor. The midpoint of tomographic sections is determined by multiplying the anteroposterior diameter of the patient by 0.4.