Measuring stone volume – three‐dimensional software reconstruction or an ellipsoid algebra formula?
- 15 January 2014
- journal article
- research article
- Published by Wiley in BJU International
- Vol. 113 (4), 610-614
- https://doi.org/10.1111/bju.12456
Abstract
To determine the optimal method for assessing stone volume, and thus stone burden, by comparing the accuracy of scalene, oblate, and prolate ellipsoid volume equations with three-dimensional (3D)-reconstructed stone volume. Kidney stone volume may be helpful in predicting treatment outcome for renal stones. While the precise measurement of stone volume by 3D reconstruction can be accomplished using modern computer tomography (CT) scanning software, this technique is not available in all hospitals or with routine acute colic scanning protocols. Therefore, maximum diameters as measured by either X-ray or CT are used in the calculation of stone volume based on a scalene ellipsoid formula, as recommended by the European Association of Urology. In all, 100 stones with both X-ray and CT (1-2-mm slices) were reviewed. Complete and partial staghorn stones were excluded. Stone volume was calculated using software designed to measure tissue density of a certain range within a specified region of interest. Correlation coefficients among all measured outcomes were compared. Stone volumes were analysed to determine the average 'shape' of the stones. The maximum stone diameter on X-ray was 3-25 mm and on CT was 3-36 mm, with a reasonable correlation (r = 0.77). Smaller stones (15 mm towards scalene ellipsoids. There was no difference in stone shape by location within the kidney. As the average shape of renal stones changes with diameter, no single equation for estimating stone volume can be recommended. As the maximum diameter increases, calculated stone volume becomes less accurate, suggesting that larger stones have more asymmetric shapes. We recommend that research looking at stone clearance rates should use 3D-reconstructed stone volumes when available, followed by prolate, oblate, or scalene ellipsoid formulas depending on the maximum stone diameter.Keywords
This publication has 10 references indexed in Scilit:
- Predictors of Clinical Outcomes of Flexible Ureterorenoscopy with Holmium Laser for Renal Stone Greater than 2 cmAdvances in Urology, 2011
- Quantification of Urinary Stone Volume: Attenuation Threshold–based CT Method—A Technical NoteRadiology, 2011
- Stone measurement by volumetric three‐dimensional computed tomography for predicting the outcome after extracorporeal shock wave lithotripsyBJU International, 2009
- Urinary calculus: IVU vs. CT renal stone? A critically appraised topicAbdominal Radiology, 2007
- Three-dimensional assessment of urinary stone on non-contrast helical computed tomography as the predictor of stonestreet formation after extracorporeal shock wave lithotripsy for stones smaller than 20 mmInternational Journal of Urology, 2007
- Stone Burden in an Average Swedish Population of Stone Formers Requiring Active Stone Removal: How Can the Stone Size Be Estimated in the Clinical Routine?European Urology, 2003
- The accuracy of noncontrast helical computed tomography versus intravenous pyelography in the diagnosis of suspected acute urolithiasis: A meta-analysisAnnals of Emergency Medicine, 2002
- Three-Dimensional CT-Scan Reconstruction of Renal CalculiEuropean Urology, 1997
- Calculation of Stone Volume and Urinary Stone Staging with Computer AssistanceJournal of Endourology, 1989
- Size of Renal Calculi, Recurrence Rate and Follow-upBritish Journal of Urology, 1976