T VU1, L KUHNEL1, R ELLIS1,2, P TRNKA1,3
1Faculty of Medicine, University of Queensland, Brisbane, Australia, 2Department of Urology, Princess Alexandra Hospital, Brisbane, Australia, 3Department of Nephrology, Queensland Children’s Hospital, Brisbane, Australia
Aim: To estimate average kidney morphometric parameters in a large sample of healthy living kidney donors using a simple method based on existing CT images.
Background: Existing studies evaluating standard kidney morphometric parameters are limited by small sample sizes. Methods of estimating volume are also tedious and time consuming.
Methods: Pre-donation CT scans from a sample of 388 living kidney donors from a single centre in Brisbane, Queensland were used in this study. Two independent investigators recorded measurements of the largest coronal, sagittal and transverse diameters of the kidney. Cortical and medullary thickness was also recorded, as was the number of pyramidal structures. Kidney volume was determined using an ellipsoid volume equation. Results were compared between investigators, and mean (± standard deviation) values were reported descriptively.
Results: Mean volumes of the left and right kidney were 202±43cm³ and 187±40cm³, respectively. Average combined volume was 195cm³. Males tended to have larger kidneys than females (218cm³, n=175 and 175cm³, n=213, respectively). There was good concordance between investigators for estimated kidney volumes (mean difference -8.9cm³, r² 0.88). The mean thickness of the cortex and medulla was 6.4±1.2mm and 16.0±3.0mm, respectively. There was an average of 6.1 pyramids on the right and 5.6 pyramids on the left kidney.
Conclusions: This is the largest study of which the authors are aware to evaluate kidney volume and other morphometric parameters using estimates derived from CT imaging. There was good concordance between investigators, and the results were consistent with previous literature, supporting the validity of this method.
Dr Robert Ellis is a resident at the Princess Alexandra Hospital and lecturer at the University of Queensland.