Three Dimensional Reconstruction And Visualization Model Of Sinus-Skull Base

The application of the transnasal endoscopic sinus brings skull base surgery intoa minimally invasive era, because space of the nasal cavity is narrow, and the eyes,brain and the important blood vessels and nerves go through the operative area, therisk of surgery is increased. So the navigation technology improves fast. The imagesof the surgical navigation system display three views. Surgeons need clinicalexperience and long-term training to form a three-dimensional image from thetwo-dimensional image in their own minds to guide the surgery. There are moresubjective factors, therefore it is necessary to establish a display system what isobjective, intuitive and suit to the human visual. The display system of the navigationinclude of, image registration. Three-dimension reconstruction of medical image datais commonly from CT and MRI for navigation at home and broad. The data from CTscanning which is good to the bone structure is the most commonly to used in thenavigation of the paranasal sinus and skull base surgery. We are more concerned tothe important blood vessels and space-occupying lesions in the paranasal sinus andskull base surgery. In this study, we segment and reconstruct the three-dimensionalvisualization model of the nasal cavity, the sinuses, the skull base and the internalcarotid artery which is suitable for the display system of navigation based on the CTplain and enhanced scanning data. And assess the model reliable and practicality.The first part: The Three-dimensional reconstruction of the Nasal-skullbase based on the the data of the CT scanningObjectiveTo analyze the segmentation and reconstruction method of the nasal cavity, thesinuses, the skull base, the carotid artery and the orbital structures based on the CTscan data. And investigate feasibility of the method and practical value of3D model in display system of image navigation and clinical teaching.Methods(1) Research object:11patients with plain and enhanced CT scanning in thePeople’s Liberation Army General Hospital during September2010and February2012,7males and4females, ages from14to57years old.(2) Equipment of Acquisition CT scanning data and3D reconstruction:Acquisition of CT plain and enhanced scanning data from64-slice Siemens spiral CTwith the reconstruction slice thickness <0.75mm. And store in the CD with DICOMformat. Then upload the data to the software of FitMe DICOM viewer for imagesegmentation and3D reconstruction.(3) Investigation of the3D medal on the clinical application and teaching:Compare of the scoring time for structures in3D and2D imaging between differentpeople.Results(1) Segmented images boundary is clear, complete, the model of reconstructionof the nasal cavity, paranasal sinuses, orbital and tumor is continuous, and it can bedisplayed the structure of the real one, provided for doctors which is meet the spatialimagination of the image. The model can be observed the organizational relations atany arbitrary rotation angle, and be measured three-dimensional volume and distancebetween two points.(2)Three-dimensional reconstruction models visually show the morphology ofthe skull base and internal carotid artery. After image registration, it can be observedthe relationship in specific anatomic landmarks of the nasal cavity, lesions andinternal carotid artery to avoid arterial injury and provide a reference for surgery.(3)The time to identify the Petrous and Cavernous segment of the internal carotidartery in the3D imaging by two groups, the low seniority and the high qualification,4.1±0.707seconds and3.5±0.527seconds were both lower significantly than that of control group96.4±20.4seconds and24.6±5.835seconds（p<0.01）.ConclusionReconstruct the segmentation and3D visualization methods of the sinus and skullbase image based on the thin-section CT data of the sinus using medical imageprocessing system which is independent intellectual property of our hospital. Themethod is convenient, reliable. The three-dimensional model displays objective,consistent with human visual habits. And that lay the foundation for virtual endoscopy,preoperative planning, directing clinical operations and clinical teaching, theestablishment of three-dimensional surgical navigation, intuitive3D display system.The second part: CT virtual endoscopy in the preoperative planning ofendoscopic surgeryObjectiveStudy the clinical significance of CT virtual endoscopy (CTVE) in the sinus andskull base surgery preoperative planning.Methods(1) Research object:10patients in the People’s Liberation Army General Hospitalduring September2010and February2012,7males and3females, ages from14to57years old.(2) Observation, measurement and surgical simulation using the3D model in thefirst part: Observe the reconstruction model and compared with endoscopic images.Measure the maximum diameter of models of tumor and compared with the maximumtumor diameter in the two-dimensional image.Results(1)Display of nasal structure and virtual endoscopic surgical simulation: it is clearly to show patients’ all turbinate and nasal septum structure. Whether theobservation of the nasal septum deviation, it is in order to choose a right approach orto choose a nasal septum correction surgery at first. Change transparency of the model,you can observe the relationship of the organizational structure which is sheltered tosuggest that where is the important structural technique and avoid injury.(2)The maximum diameter of the tumor model is (43.40±15.83) mm in thethree-dimensional image, and (41.28±13.95) mm in the two-dimensional image. Thecorrelation coefficient r=0.994, P <0.001, that there is significant correlationbetween paired variables. And t=-2.696, P=0.025, it is felt that there was significantdifference between the maximum tumor diameter measured by two methods.ConclusionCT virtual endoscopy can be clear, accurate, and stereo to display the spatialrelationships of anatomical structures and landmarks in the endonasal endoscopicapproach surgery. It is beneficial to choose the preoperative treatment options andsurgical approach, give doctors more intuitive, comprehensive estimate for the lesionbefore surgery. It can display the internal carotid and orbital wall to avoid the risk ofsurgery and lay the foundation for the establishment of stereo, intuitive3D displaysystem of the surgical navigation. This can avoid the risk of surgery and have greatbenefit to the training of young doctors and the teaching clinical anatomy.