Amiryaghoub Lavasani: Dear viewers, my name is Amir Lavasani, and I am 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, Assessment of The Accuracy of 3D Slicer Versus Ellipsoid Formulae For Stone Volume Measurement: Size Matters.

Accurate stone volume estimation is essential in both research and clinical settings, yet conventional ellipsoid formulae determined volumes often fall short due to the irregular shape of stones. While gas spectrometry is the gold standard for volume measurement, it is not feasible for clinical practice preoperatively. CT based volumetric software such as 3D Slicer present a promising alternative for more precise and practical stone volume measurements.

This study aims to analyze the accuracy of volumes determined by ellipsoid formulae and 3D Slicer compared to gas pycnometry. In our study, we analyzed 64 air dried human stones under 1.5 centimeters, and 54 large custom made bigger stones in various shapes over 1.5 centimeters.

The volumes of all stones were first obtained via gas pycnometry, to serve as the gold standard. The stones were then CT scanned in two different mediums, suspended in air and embedded in a silicone phantom. Independent reviewers obtained stone volumes from CT scans using 3D Slicer, along with the prolate ellipsoid formula for small stones under 1.5 centimeters, and the scalene ellipsoid formula for large stones over 1.5 centimeters.

An analysis of variance with Dunnett's test was performed to compare measurements across groups and mediums by maximum linear measurement. Our results revealed that compared to gas spectrometry, the ellipsoid formula significantly overestimated stone volume, regardless of stone size or scanning medium.

Similarly, 3D Slicer also significantly overestimated small stone volumes. However, 3D Slicer was not statistically significant from gas pycnometer for large stones greater than 1.5 centimeters.

In conclusion, the ellipsoid formulae overestimate stone volume regardless of size and medium. 3D Slicer offers accurate volume measurements for stones larger than 1.5 centimeters, though it tends to overestimate volumes for smaller stones. Thank you for your time.