Reconstruction Of The Digital Model Of The Sacral Neural Tube And Three-dimensional Visualization Research Based On CT Image

Objective: Sacrum fracture accounts for about20%~30%in pelvicfracture，among which22%~60together with neurological symptoms. Whensacrum suffers powerful force, it may be bone fracture and lose symmetry,which results in deformation, shrinking of sacrum hole and press on sacrumnerve. Also by which some functional disorder may be accompanied. Sacrumfracture together with sacral nerves injury is a common clinical severe injury.Operation is the most often used in clinicaltreatment for this injury at present.As a result, having a good knowledge of how the sacral neural tube runs andspreads could make the clinician know thoroughly when they operate onsacrum fracture and sacralnerve decompression. To observe how the sacralnerve runs in sacral neural tube, two methods can be used, they are, bodyanatomy and imageanatomy. As the sacral neural tube is a hermetic tube insacrum, so it isneed to be sectioned, observed, measured, or molded if wewant toknow the exact distributions and runs of the neural nerves by bodyanatomy. It no wonder makes the experiment more difficult. Besides, quite alot of bodies are needed to carry out this experiment, while the body is scarceand price is high, all of which may hinder the development of body anatomy.Pelvis and sacrum can be3d-reconstructioned at CT workstation and thereconstructed image is clear enough to determine the position and feature ofthe bone fracture. The form of sacral hole andwhether bone block is existed insacral hole can be displayed by computed tomography. However, how thesacral nerves run and spread in theneural tube cannot be reflected very wellbecause it is used to diagnoseand observe surface condition. Thus, theexperiment builds the3d visualized digital model of the walk line of sacralnerves in sacral tubes thatmost easily are injury in bone fracture by usingMimics software. The results of observing the walk line and of measuring the angles can be much visualized which can also help the operator to deepen theunderstanding. The purposes of this experiment lie in three aspects. First,explorethe construction of3d digital model and visualized method of sacralneural tube; second, know the structure and the angles between thesacralnerves and the nerves around can strengthen the operator’sunderstanding of how sacral nerves runs in the tube, which provide afoundation of treat sacral bone fracture and sacral nerve injury; third, enrichthe clinicalresearch methods and provide effect reference to the projectionangleof sacral neural tube during operation, and thus improve the accuracyofscrew placement in sacrum fracture and the accuracy of sacral nervedecompression.Method:All of20volunteers have a CT scan of sacrum.The SIEMENSCT(SIEMENS company,Germany)is sixty-four detectorrow spiral CT.Thecondition of scanning:voltage120KV,electric current150MA,thickness5.0mm,matrix512×512.And syngo CT WORKSTATION was used for dataprocessing.All the images were saved as DICOM format and imported to thepersonal computer.Construct the three-dimensional digital models of sacralneural tube and Sacral spinal，truly rendering the accurate Position of thesacral nerve in sacral neural tube.Choose the3D measurement tool of Mimicsto make3D measurement of the angles before and after the sacral vertebralneural tube, and place cylinder model among the sacral neural foramen tomeasure the angle of the centerline of the cylinder model between verticalplane and bed surface as well as cross section and bed surface vertical linerespectively.Results:Successfully construct the digital models of sacral neuraltube,intuitive shows sacral neural tube holder in the sacrum and direction. Onthe left side,the angles between the sacral neural tube before and after of S1were94.10°±3.72°,on the right side,the angles between the sacral neural tubebefore and after of S1were93.21°±4.19°, the difference was not statisticallysignificant (P>0.05). On the left side, the angles between Sacral foramen axialand the baseline were46.24°±4.24°on the sagittal plane,on the right side, the angles between Sacral foramen axial and the baseline were47.74°±5.32°onthe sagittal plane, the difference was not statistically significant; On the leftside, the angles between Sacral foramen axial and the baseline were26.27°±3.75°on the cross section,on the right side,the angles between Sacralforamen axial and the baseline were26.66°±2.65°on the cross section,the difference was not statistically significant.Conclusion: The sacral neural bone channel has been first established inthis research by Mimics software. That is3D visualized model, whichcharacterizes it with physical feature and more accuracy and it can reflectmorphological feature of sacral neural tube more completely, comprehensively,and directly. By measuring the angle before and after S1neural tube and theshafting position of the S1neural foramen between vertical planes, crosssection and bed surface vertical line, the operator’s knowledge of how sacralnerve tube distributes and runs can be strengthened. It also comes up with theperspective angle of sacral neural foramen shafting position, which improvesthe accuracy of screw placement in sacrum fracture and the accuracy of sacralnerve decompression.