Page 37 - Advanced concepts in orbital wall fractures
P. 37

                                Results
Validation of the anterior boundary
Two observers indicated the landmark points on ten CT scans. The ICC C was 0.992 (95 % CI 0.956–0.998) when comparing the orbital volumes 2 after the cut-off by the anterior planes reconstructed by the different
observers for all datasets. The mean difference for the resulting volumes
was 0.17 cc (SD 0.24).
Validation of the gold standard
Two observers performed the manual segmentation for ten scans. The mean volume of all calculations was 29.9 cc (SD 2.26). The intraobserver ICC was 0.997 (95 % CI 0.987–0.999) with a mean difference of 0.09 cc (SD 0.18). The interobserver ICC was 0.994 (95 % CI 0.976–0.998) with a mean difference of 0.03 cc (SD 0.27).
Gold standard versus three (semi-)automatic segmentation methods
All 21 orbits were segmented to compare the gold standard to the three different methods (Table 1). Method A had a mean difference of 0.49 cc (SD 0.74) in comparison with the gold standard. The average time was 38 s (SD 5.4) per orbit. Method SA had a mean difference of 0.24 cc (SD 0.27) with the gold standard segmented orbits. The average time was 146 s (SD 16.0) per orbit. Method SAA gave a mean difference of 0.86 cc (SD 0.27) to the gold standard segmentation. The average time was 327 s (SD 36.2) per orbit. The ICC for the intraobserver variability was 0.998 (95 % CI 0.991–0.999) and the interobserver variability 0.990 (95 % CI 0.890–0.998) for method SAA.
Volume segmentation method
 35
























































































   35   36   37   38   39