Experimental study on ultra-high resolution CT imaging anatomy of single neural canal / 中华放射学杂志

ABSTRACT

Objective:To re-identify the anatomical features of singular nerve canal (SNC) through observing and measuring the morphological characteristics of SNC using ultra-high resolution CT (U-HRCT).Methods:The U-HRCT images of 52 human head specimens (104 ears) from December 2019 to January 2020 were obtained. The best standard cross-sectional and coronal images of SNC were reconstructed. The morphology of the main trunk and branches of the SNC were observed. According to the number of turning points, the trunks of SNC were divided into single turning point type, double turning point type and no turning point type. According to the branch morphology, the branched SNC were divided into bifurcated type, confluent type, side branch type and bilateral branch type. The diameter, angle and length of each section of the posterior canal ampulla (PCA) of the main trunk, the turning point and the internal auditory meatus (IAM) were measured. Independent sample t test or Mann-Whitney U test was used to test group differences of main trunk diameter of the SNC with or without branches. Results:Totally 104 ears of 52 cases were divided into single turning point type of 79 ears, double turning point type of 20 ears and no turning point type of 5 ears. The bilateral morphological classification was the same in 30 cases (60 ears), including 24 cases of single turning point type (48 ears), 5 cases of double turning point type (10 ears), and 1 case of no turning point type (2 ears). The ear morphology on both sides was different in 22 cases (44 ears). The diameters of the PCA, the turning point and the IAM of SNC with single turning point type were (0.31±0.07), (0.40±0.10), (0.46±0.10) mm, respectively, and the angles were 60.5°±7.8°, 120.3°±9.6°, 38.3°±7.5° respectively. And the length of the PCA and the IAM in the SNC with single turning point type were (1.95±0.38), (2.31±0.68) mm, respectively. The diameters of the PCA, the turning point near the PCA, the turning point near the IAM and the IAM of SNC with double turning point type were (0.32±0.09), (0.38±0.09), (0.47±0.12), (0.47±0.13) mm, and the angle were 60.9° (57.3°, 64.9°), 117.9°±12.3°, 129.6°±12.4°, 41.7° (32.9°, 79.5°), respectively. The length of the PCA, the IAM and the distance between these two turning points were (1.78±0.31), 0.65 (0.46, 1.15), 0.96 (0.80, 1.15) mm, respectively. The diameters of the PCA and the IAM of SNC without turning point type were (0.20±0.01) and (0.50±0.12) mm. The angles with the PCA and the IAM in these cases were 58.4°±9.6° and 46.2°±5.1°, and the length was (3.61±0.32) mm. A total of 48 ears had branches, including bifurcated type (36 ears), confluence type (4 ears), side branch type (5 ears) and bilateral branch type (3 ears). In the SNC group with single turning point, the diameter of the turning point in the cases without branches was wider than that of cases with branches ( t=2.11, P=0.039). However, there was no significant difference in the diameter of each section between these two subgroups of SNC cases with double turning point type. Conclusions:U-HRCT is able to clearly show the SNC, the imaging features of whom are variable and should be re-understood.