| Nasal endoscopic technique with its direct, minimally invasive features has beenthe conventional techniques in ENT. With the development and improvement of nasalendoscopic, the range of nasal endoscopic has been extended to the deep structure ofskull. Because of the skull base is deeper in the head and with complex anatomicalstructures, the development of endoscopic skull base surgery needs more intuitive,rich image information of skull base region and intraoperative navigation technology.The existing intraoperative navigation use CT or MRI image to display structure andoperating location. CT can provide high quality image on bone and other higherdensity tissue, but show poor on the soft tissue structures; MRI can provide highquality image on soft tissue structures, but show poor on bone. There has been CT-MRI image fusion and other multimodal imaging information technology applying inneurosurgery and oral-maxillofacial surgery, but fewer in endoscopic sinus and skullbase surgery. We plan to use CT-MRI fusion images in three-dimensionalreconstructing the structure of paranasal sinus and skull base and applied in the3Dstereo display system of operation navigation system.This study uses the image processing system of independent intellectualproperty rights to do registration, fusion, segmentation and3D reconstruction basedon CT-MRI image fusion, by using methods of virtual endoscopic, volume renderingsegmentation, automatic and artificial space measurement to study CT-MRI fusionimages in3D reconstruction of endoscopic sinus and skull base surgery.Part one: The registration, integration, segmentation and3D reconstruction ofhead CT-MRI image.Objective: This study is to do image registration, fusion, segmentation and3Dreconstruction of head CT-MRI. Methods: In this study we selected patients withhead enhanced CT and MRI images as the research object, and use the image processing system of independent intellectual property rights for operation. We selectthe center of both side eyes, the second cervical vertebrae and foramen magnum asthe registration point to register and fuse. We segment the skull and internal carotidartery on the enhanced CT image and tumor, nasal septum, inferior turbinate, middleturbinate on CT-MRI images, and then reconstruct them. Results: The importantanatomic marks on the fused image of CT-MRI are good in coincidence with theknowledge of anatomy. CT-MRI fusion image can show the structure information ofbone and soft tissue of the head clearly and more plump than a single CT or MRI.Following the steps of registration, fusion and3D reconstruction steps, the structureboundaries are clear and without overlapping. The reconstruction of the structureshowed complete, continuous and smooth. Conclusion: The method of using thecenter of eye, the second cervical vertebrae and foramen magnum to register is non-invasive, simple, and can be used for head CT-MRI image registration. It can reducethe distortion of MRI image by following the steps of registration, fusion and three-dimensional reconstruction. The model can more accurately reflect the size of softtissue.Part two：The application of three-dimensional model in the surgical three-dimensional navigation system.Objective: The object of this study is the application of three-dimensional model inthe surgical three-dimensional navigation system. Methods: Use the virtualendoscopic function of the image processing system to display the structure ofparanasal sinuses-skull base, and compared with the vision of the tissue structureunder real endoscopic and three views. Results: Each three-dimensionalorganizational model of skull base can be clearly displayed under the observation wayof nasal endoscopy, and is similar with the real endoscopic morphology and spatialrelationships. It has smooth regulation of three-dimensional rotation and transparency.The relationship of the tumor, surrounding nerves and blood vessels cannot bedirectly observed under the real endoscopy and three views. Conclusion: The three-dimensional reconstruction models based on the CT-MRI image fusion under theapproach of virtual endoscopic can realize the observation of skull base structure frominternal nasal. Three-dimensional model in three-dimensional navigation in displaying the structure of skull base is intuitive, convenient, and workable than the realendoscopy and three-view navigation. It can be used in operation planning,assessment of operation risk, and laid the foundation of navigation for three-dimensional image display.Part three: The application of three-dimensional model based on CT-MRIfusion images in the preoperative planning with the three-dimensionalnavigation.Objective: The object of this study is the application of three-dimensional modelbased on the CT-MRI image fusion in the preoperative planning of paranasal sinuses-skull base surgery. Methods: Reconstruct the soft tissue model based on the CT-MRIfusion image by surface rendering. Reconstruct the skull model based on enhancedCT by volume rendering. Combine the soft tissue model and the skull model together.Use the volume rendering segmentation function to segment the skull model. Observethe spatial relationship between skull model and soft tissue models by exposing thebone marks of skull from outside to inside regularly. Results: The volume renderingmodel based on enhanced CT and surface rendering model based on CT-MRI fusionimage can display the structure of paranasal sinuses-skull base through thecombination between the models. Volume rendering segmentation can make a clearthe boundary of skull stump and a smooth edge and expose the spatial relationshipbetween bone marks and soft tissue models of head. Conclusion: The surfacerendering models based on the CT-MRI image fusion can work together with thevolume rendering models. With the method of volume rendering segmentation, it canrealize operation planning, assessment of operation risk, and laid the foundation ofnavigation for three-dimensional image display by exposing the bone marks of skullfrom outside to inside gradually.Part four: The study of the space measurement on the three-dimensional modelof paranasal sinuses-skull base.Objective: The spatial measurements on structure and space-occupying lesions ofthree-dimensional model of paranasal sinuses-skull base. Methods: Use the automatic and manual space ranging methods of image processing system to measurethe maximum diameter of tumor model of25cases patients. Use image processingsystem to measure model maximum diameter as automatic method. If the tumor ismultiple, only one model will be measured. Randomly select10clinicians in ourdepartment as operators, uses the manual measurement function of image processingsystem to measure the maximum diameter of each model and record the average valueof each model as the manual method. Statistic the results of maximum diametercollected from automatic method and manual method. Results: The numbers of themaximum diameter are32.007mm of automatic method and30.240mm of artificialmethod. The numbers of standard deviation are15.311of automatic method and15.169of artificial method. The image processing system can automatically displaythe maximum diameters of the tumor model and the location of space distancesbetween models and distinguish them by different color lines. Conclusion: Theautomatic measurement method can work better on space ranging of three-dimensional model based on CT-MRI fusion image, on operation planning andassessment of operation risk, and spatial measurements. |
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