Avoidance of errors related to renal depth during radionuclide evaluation of renal perfusion

Quantitative renal imaging is subject to errors related to varying renal depth. Lateral projection images, ultrasound, and geometric mean calculations can be utilized to measure renal depth or to correct for variations in the attenuation of renal activity. However, each of these methods is time consuming and each has the potential for introducing additional errors. As an alternative, the authors propose the use of quantitative indices that are insensitive to the effects of attenuation. This report illustrates how transit-time-distribution (TTD) parameters can be used to assess renal perfusion independent of varying renal depth.