Renal volume assessment with 3D ultrasound

Purpose: This study was undertaken to determine the accuracy of 3D ultrasound (US) in assessing renal volume, with multislice computed tomography (MSCT) considered as the gold standard. Materials and methods: Forty-nine patients (30 men, 19 women; age range 30-82 years) underwent abdominal contrast-enhanced MSCT and 3D-US performed with a 3.5-MHz 3D/4D convex-array probe. The results of the two modalities were compared with the Wilcoxon test. Variability between the two measurements was determined with the Bland-Altman method and reported in terms of bias and coefficient of repeatability (CoR). Results: Mean values obtained were 210 ml with MSCT and 192 ml with 3D-US (p<0.001). Analysis of variability per patient between MSCT and 3D-US showed a bias of 19 ml, a CoR of 47 ml and an accuracy of 78%, with an average 3D-US underestimation of 19 ml (9%). Analysis of variability per kidney showed a bias of 9 ml, a CoR of 34 ml and an accuracy of 80%. Conclusions: Three-dimensional US is a valuable technique for monitoring renal volume, whereas MSCT may be reserved for assessing renal anatomy and relationships with neighbouring organs.