Seyed Amiryaghoub M. Lavasani: Dear viewers, my name is Amir Lavasani and I'm a research specialist with the Department of Urology at the University of California Irvine. I am pleased to present our work on stone volume validation in the following study titled, More Than Just Size: The Search for Accurate Stone Volume Assessment. Accurate determination of CT-based stone volume is imperative in order to facilitate both clinical practice and research.

However, clinical and widespread methods such as maximum linear measurement and ellipsoid formulae remain limited due to irregular stone shapes. CT-based 3D Slicer, Enterprise Imaging, and Visage imaging are alternative methods that may provide increased precision for determining stone volume. We compare the accuracy of each of these methods, including four Visage techniques versus gas pycnometry, the gold standard for volume determination. We analyzed two groups of stones, 64 small human stones under 1.5 centimeters, group one, and 54 Bego stones over 1.5 centimeters, group two.

The true volume of all stones were determined. For stones less than 1.9 centimeters, volumes were determined using gas pycnometry. For stones greater than or equal to 1.9 centimeters, water displacement was used. Water displacement volumes were validated against gas pycnometry, yielding a mean error percent of 1.4% between the two methods. Subsequent CT scanning was completed for all stones in air and following placement in a silicone phantom. Independent reviewers determined stone volumes using each of the seven methods. Data were analyzed using ANOVA with Dunnett's post-hoc test stratified by size and medium. Enterprise Imaging and Visage using the balloon contour tool were the two methods that consistently outperformed all other methods. In air for stones across all sizes, both were not significantly different from gas pycnometry. This was observed again in the phantom.

For stones across all sizes, Enterprise Imaging and Visage using the balloon contour tool were similar to gas pycnometry. In the figure, stone volume using four different methods in a phantom for a single large Bego stone is shown. Only Visage and Enterprise were similar to gas pycnometry. In conclusion, the ellipsoid formulae consistently overperformed stone volume regardless of stone size or imaging environment. Among all methods, Enterprise Imaging and Visage with balloon contouring demonstrated the most consistent accuracy regardless of stone size. Thank you for your time.