Table 2.
Correlation between a manual versus semi-automated method of measuring stone size
| Variables | Manual method | Semi-automated method | Pearson r correlation |
|---|---|---|---|
| Major horizontal axis length (mm)a | 6.6 (5.4–9.0 [3.0–20.8]) | 6.9 (5.7–8.9 [3.4–20.1]) | 0.97 |
| Major vertical axis length (mm)a | 7.2 (4.7–9.3 [2.6–16.3]) | 7.5 (5.7–10.5 [2.6–21.0]) | 0.88 |
| Manual volume estimation using different equations for the volume of an ellipsoid | |||
| Oblate | 161 (71–379 [13–3347]) | 113 (62–276 [21–1820]) | 0.94 |
| Scalene | 100 (40–247 [10–1420]) | 0.94 | |
| Prolate | 65 (24–181 [1–1172]) | 0.83 | |
Values are median (IQR [range])
aValues were measured from the largest cross-sectional slice of the stone manually. The manual method of calculating stone volume used the following formulas for an ellipsoid: oblate ellipsoid (π/6 × a × a × c), scalene ellipsoid (π/6 × a × b × c) and prolate ellipsoid (π/6 × a × b × b)