The use of a CT-based navigation system for the endoscopic anatomy of the optic canal

Objective To recognize the endoscopic anatomy of the optic canal using a computer-assisted navigation system based on three-dimensional computed tomography (CT).Methods This was an experimental study.Eight adult damp cadaveric heads were studied bilaterally (n=16).We approached each optic canal through each nostril assisted by the CT-based navigation system to measure the optic canal and its related structures and compare it to the gross anatomy.Results In endoscopic anatomy,the distinguishing ratios for optic protuberance (OP),carotid protuberance (CP),and opticocarotid recess (OCR) were 62.5％,75％,and 75％,which were consistent with the gross anatomy.In the endoscopic anatomy,the distances from the midpoint of the medial wall of the optic canal orbital aperture and cranial aperture to the anterior nasal spine were 71.19±4.00 mm and 79.69±3.65 mm,respectively.The mean length of the medial wall of the optic canal was 10.00±1.71 mm.The mean diameters of the optic canal orbital aperture and cranial aperture were 4.46±0.56 mm and 4.71±0.42 mm,respectively.There was no statistically significant difference between CT endoscopic anatomy and gross anatomy (P＞0.05).Conclusion The computer-assisted navigation system based on the three-dimensional CT can map the optic canal accurately.With the help of the CT-based navigation system,a surgeon can perform the operation safely and effectively. Key words: Imaging,three-dimensional; Endoscopic; Optic canal; Optic nerve decompression; Anatomy