Ultrasonographic determination of renal mass and renal volume.

Volumes and surface areas of 45 kidneys were determined ultrasonographically in vivo before autopsy and in a water bath phantom after autopsy by means of both the ellipsoid and the stepped section methods. Comparison of results revealed that renal volume may be determined by the simplest method, the ellipsoid method, with sufficient accuracy for clinical use. Results also revealed that renal mass expressed in grams may be directly obtained from renal volume expressed in milliliters, but mass in grams was found to correlate better with renal surface area than with renal volume. A formula relating renal mass to both volume and surface area was developed from regression analysis of the data and was found to provide a more precise estimate of renal mass than does mass computed from either volume or surface area alone.