Construction Of The Digital Model Of Sellar Area Tumour And Its Application In Preoperative Evaluation

Objective To reconstructe the anatomical structures of sellar tumor by virtual reality technology, to investigate the construction methods and improvement measures of tumor models by observing the anatomical images. And to probe the value of tumor models in the real operation by comparing with the intraoperative images. Describe the anatomic orientation signs of single-nostril transsphenoidal in the virtual reality environment by observing and measuring the pituitary adenoma models, simulate the surgery processing according to the observations on models. To summarize the identification method of the important anatomy assisted models and explore the value of the models in the preoperative evaluation of this approach according to the intraoperative findings.Methods 60 patients with sellar tumor were diagnosed by MRI scan, their lamellar sequences of CT, MRI were collected before operation. Then, the scan data were imported to Dextroscope imaging workstation, the anatomic structures like sella turcica, ICA, the circle of Willis and its branches, ON and OC, brain tissue were divided and rebuild. Different sellar approach were simulated and the real intraoperative anatomical relationship were compared according to the observations on models. The 30 cases of pituitary adenoma models were researched in detail based on the sellar tumor models. The relevant anatomic landmarks and tumor feature were observed and measured and the single-nostril transsphenoidal approach were simulated too. Lastly, the operations were performed according to the surgical principle and observations, and the anatomy between the virtual findings and intraoperative findings were compared at the same time.Results 1. All sellar tumor models can clearly displayed bone, ICA, Willis ring and its branch, optic nerve and chiasm, ventricular system, tumor, brain, soft tissue and adjacent structures. There are more impressive than the other three-dimensional reconstruction image, and they can freely observed the anatomic landmarks for surgical approach in any angle and orientation.2. The models required that the image sequence must be thin sectional images. CT for skull and skin, CTA for cerebral vascular, MRI-T1WI for the brain, optic nerve and the ventricular system, MRI-T1WI contrast-enhanced sequences for tumor tissue, is better than the other sequences in the aspect of extracting images.3. Selecting anatomical landmarks and surgical gaps through virtual tool can simulate the operations of opening the skull flap, removing tumor and others, can also simulate the exposure angle and the rang of surgical field, all the operations are for mastering the plan to protect the optic nerve, Willis ring, third ventricle, and the brain stem in the real operation.4. In the specific applications of pituitary adenoma models, we simulated the single nostril-transsphenoidal surgery. With the columella as a symbol, we measured the distance from the columella to nasal septum cartilage, sphenoid sinus opening and the distance from the midpoint of the anterior nostrils plane to the shallow point of anterior wall of the sphenoid sinus. To mark the midpoint of sellar floor, the distances were measured from here to the cavernous segment of ICA, optic canal, tuberculum sellae and dorsum sellae. The angle between the line of nasal columella-glabella and the direction of apporach were measured.5. In the VR environment, we observed the oriented anatomic landmarks through the approach angle, such as the nasal septum, the broken ends of vomer bone or lamina mediana, aperture of sphenoidal sinus, sphenoidal cavity, sellar floor. We successfully simulated the approach through the characteristics of individual anatomy and tumor, the intraoperative findings mainly accorded with the virtual findings.Conclusion 1.The images of all sellar tumor models are stereoscopic and clearly using virtual reality technology to rebuild, can provide additional three-dimensional anatomical information for surgeon, to make up the shortage of two-dimensional cross-section images, to help judge the close of the tumor and anatomical variations of the approach.2. Dextroscope VR workstation provides virtual devices which can exercise operation on the model repeatly without any harm to patients. We can repeated the operation to explore the surgical considerations In the real surgery. Compared with the conventional two-dimensional section images, the images of models simplifies the integrated thinking process of surgeon. This is an effective complement to routine clinical operation planning.3. All sellar tumor models support the original recovery in the VR environment although can't achieve the practical effect of cadaveric head, but still can show the gross anatomy of sellar region, especially the patho-morph. The tool for studing pathological sellar anatomy and surgery were provided and the intelligence of medical students were increased by the cases reconstructed, they no longer limited to the conventional materials and animal models.4. To search the individual anatomic landmarks for orienting and to avoid damaging the surrounding tissue, through observing the location of nasal septum, nasal turbinate, anterior sphenoidal wall, aperture of sphenoidal sinus, the broken ends of vomer bone or lamina mediana, septum of sphenoidal sinus and sellar floor.5.As observated and measured the anatomic shape of aperture of sphenoidal sinus, sellar floor and tumor, we can understand the scope of bone window in the anterior sphenoidal wall and sellar floor, get the orientation of dissectting tumor, avoid damaging the important anatomic structures.