| Objective:Using imaging data study the anatomical features of normal optic canal and find a reconstruction method that can accurately detect optic canal fractures to provide a reliable imaging basis for clinical diagnosis.Methods:A total of 43 patients with unilateral TON who underwent neurosurgery from the First Affiliated Hospital of China Medical University from December 2016 to November 2018 were enrolled.These patients was performed by the HRCT orbital scan before operation and the optic canal fracture was confirmed by endoscopy.The image data was reconstructed using the GE AW4.7 workstation at our imaging center.On the one hand,we measured the length of each wall of the normal optic canal and the vertical diameter,transverse diameter and cross-sectional area of the cranial opening,orbital opening and middle of the canal by the GE AW4.7 workstation.On the other hand,according to endoscopic fractures of the affected side optic canal,the fracture types were divided into five types:linear fracture,depressed fracture,embedded fracture,smashing fracture,and mixed fracture.The results of the detection of optic canal fractures were observed using different reconstruction methods.we counted the number of different types of optic canal fractures and statistically analyzed the total fracture detection rate under different 3D reconstruction methods.The obtained statistical data was analyzed using SPSS20.0 software.Measurement data are expressed as mean±standard deviation(`x±s).The measurement data such as the length and area of the optic canal were first tested by F test,and then those with significant differences were tested by q test.The count data of optic canal fracture were compared by chi-square test.The difference was statistically significant at p<0.05.The count data were analyzed by chi-square test.P<0.05 was statistically significant.Results:1.The medial wall of the optic canal was the longest,with a length of(11.50±1.09)mm.The inferior wall of the optic canal was the shortest,with a length of(6.51±1.20)mm.The difference of each wall's length was statistically significant(p<0.05).The cross-sectional area of the optic canal at the orbital opening is biggest that was(18.67±3.26)mm~2 and the middle of the canal's cross-sectional area is the smallest with(14.7±2.32)mm~2.The difference between the cross-sectional area of optic canal at the orbital opening,middle portion and cranial opening orifice was statistically significant(p<0.05).2.Endoscopic findings:there were 10 cases of linear fracture,6cases of depressed fracture,4 cases of embedded fracture,15 cases of comminuted fracture and 8 cases of mixed fracture;24 cases of optic canal fracture were found by axial CT view.The detection rate was 55.8%(24/43),including 4 cases of linear fracture,2 cases of depressed fracture,4 cases of embedded fracture,10 cases of smashing fracture and 4 cases of mixed fracture.29 cases of fractures were found by axial CT view combined with CPR and VRT reconstruction.The detection rate was 67.4%(29/43),including 4 cases of linear fracture,4 cases of depressed fracture,4 cases of embedded fracture,11 cases of smashing fracture and 6 cases of mixed fractures.42 cases of fractures were found by axial CT combined with MPR reconstruction.The detection rate was 97.7%(42/43),including 9 cases of linear fracture,6 cases of depressed fracture,4cases of embedded fracture,15 cases of smashing fracture,and 8 cases of mixed fractures.Compared axial CT view with axial CT unite with CPR+VRT,the difference of detection rate between the two methods was not statistically significant(p>0.05);compared axial CT view with axial CT unite with MPR,the difference of detection rate between them was statistically significant(p<0.05).Conclusion:The middle part of the optic canal has the smallest cross-sectional area and is the narrowest part of the optic canal.The axial CT images obtained by HRCT scan combined with MPR reconstruction has the highest detection rate of optic canal fracture,which can effectively detect optic canal fracture. |
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