Article Figures & Data
Figures
- FIG 1.
Evaluation of 6 equations (e1–e6) for estimating DRG volume: Boxplots show deviation of estimated DRGvol (e1–e6) from ground truth volume (DRGvol (r) by calculating the quotient of estimated volume and ground truth volume. The closest approximation to ground truth was attained for Equation 6 (DRGvol [e6], far right): =
. The top of the box represents the 75th percentile, the bottom of the box represents the 25th percentile. The line in the middle represents the 50th percentile (median). The whiskers represent the 5th and 95th percentiles, and values beyond the lower and upper bounds represent outliers and extreme values. - FIG 2.
Colored 3D and surface volume-rendered and volume cut visualization of the volumetric results of the 6 different equations for estimation of ipsilateral DRG volume. The green shell represents the ground truth voxelwise segmentation result, DRGvol (r). The purple shell just at and very close to the outside of the ground truth shell (green) corresponds to the best optimization result, which was obtained from the new Equation 6, including an intercept, only slightly overestimating voxelwise ground truth segmentation. The pink shell just at the inside of the green shell corresponds to the new and second-best-performing Equation 5, without an intercept, slightly underestimating DRGvol (r). These 2 equations have provided the best results for estimating DRGvol. For the purpose of visualization, the shells of these 2 optimized equations are slightly offset to allow macroscopic differentiation of the small differences. Significant underestimation of volume was observed for commonly used equations e1–e4; (brown = e1, red = e2, orange = e3, and yellow = e4. The contralateral DRG is surface volume-rendered in gray).
- FIG 3.
Comparative DRG volume-rendered visualization of ground truth volume DRGvol (r) versus best estimated volume by DRGvol (e6). Left: right-anterior-oblique plane. Middle: frontal plane. Right: left-anterior-oblique. Purple DRGs on the right side with smooth surfaces correspond to estimated volumes using Equation 6 for the most accurate approximation. Green DRGs on the left side with mesh surface correspond to ground truth volumes from expert manual segmentation and contour locations.
- FIG 4.
Boxplot of DRGvol (e6) showing the DRGvol (cubic millimeters) for the different lumbosacral heights L4–S2. Equation 6 (DRGvol, e6) provided the best approximation to ground truth. By means of this equation, these boxplots display human MR imaging DRG morphometry over the clinically most relevant segments, L4–S2, in a large validation cohort (n = 510). The top of the box represents the 75th percentile; the bottom of the box represents the 25th percentile. The line in the middle represents the 50th percentile (median). The whiskers represent the 5th and 95th percentiles, and values beyond the lower and upper bounds represent outliers and extreme values. Significances are marked with asterisks (indicating P < . 0001).
