Kidney depth measurement and its influence on quantitation of function from gamma camera renography

Both total and relative renal function assessed from gamma camera renography are influenced by the depths of the kidneys in the body. Despite the ease with which renal depths may be measured (by ultrasound or nuclear medicine lateral scans), when calculating the total uptake function it is common practice to estimate the renal depth from the patient's weight-to-height ratio. Furthermore, it is often assumed that there is no significant effect on relative function measurements due to different depths of right and left kidneys. Our data, from 150 consecutive patients, does not support this assumption or the use of calculated depth estimates and highlights the need for accurate kidney depth measurement.