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Surgical preparation is enhanced by the availability of computer-generated three-dimensional models that allow surgeons to explore the surgical field in various projections prior to an actual operation. In fact, with adequate computed tomography images, an entire operation can be simulated beforehand so that surgeons can plan the safest and most effective approach and be prepared to avoid or overcome obstacles during the actual procedure. Also, computer technology allows surgeons to conduct remote consultations and to even perform telesurgery—that is, to operate on a patient from a great distance. In this article, we describe our experience with computer-assisted local and remote endoscopic sinus surgery in Croatia.

This article presents virtual reality from the idea to the realisation and it's use in medicine. The basic components for it's realisation are also described here.

We have carried out three-dimensional, computer-assisted, functional endoscopic sinus telesurgery. Surgeons at different locations up to 300 km apart could not only see and transfer video images but also transfer three-dimensional computer models and manipulate them in realtime during surgery. Two different approaches were used. In the first telesurgery procedure we used M-JPEG compression and transmitted the data using fibre optic connections (ATM OC-3) at a bandwidth of 155 Mbit/s. In the second telesurgery procedure video images were transmitted over four E1 digital lines, amounting to about 8 Mbit/s of bandwidth, with better compression standards, such as MPEG1 and 2. We found that MPEG2 video compression produced the best picture quality for the operating field and endoscopic cameras. For conferencing and consultation between two or more connected sites during the surgery, we used JPEG and MPEG1 video compression with audio. The main feature of our three-dimensional telesurgery was the use of three-dimensional modelling of the operative field. This is important for emergency surgical interventions. We do not advocate that inexperienced surgeons operate on patients, not even with the guidance of a remote surgeon. However, three-dimensional telesurgery may become very valuable for experienced surgeons in the future.

Foreign bodies in paranasal sinuses are found quite infrequently. They are usually detected after various types of head trauma and most commonly occur as a consequence of improper handling of firearms or explosives. In countries at war, eg, during the war in Croatia, adults and children were almost equally exposed to these injuries. The diagnosis should be based on results from precise computer tomography (CT) scanning in axial and coronal sections, and, using these data, tissues of different densities at these anatomical locations can be differentiated. The possibility of exact preoperative, noninvasive visualization of the spatial relationships of anatomic and pathologic structures with 3-dimensional (3D) computer-assisted diagnosis and intraoperative navigational techniques allows the surgeon to achieve a considerable advantage in the preoperative examination of the patient and to reduce the risk of intraoperative complications, all by the use of virtual surgery (VS) or virtual diagnosis. The expected contribution of the mentioned computer-assisted surgical technique manifests itself in defining the most appropriate mode of CT scanning of the head to design the 3D operating field model, and the possibility of active and dynamic 3D visualization of the desired anatomical regions is realized. 3D reconstruction of anatomic units becomes a routine preoperative procedure, providing a highly useful and informative visualization of the regions of interest, and, thus, advancing the definition of geometric information on anatomical contours of the 3D model by the transfer of so-called image pixel to contour pixel.

The main goal of our dynamic 3D computer-assisted reconstruction of a metallic retrobulbar foreign body following orbital injury with ethmoid bone involvement was to use 3D-information obtained from standard computed tomography (CT) data to explore and evaluate the nasal cavity, ethmoidal sinuses, retrobulbar region, and the foreign body itself by simulated dynamic computed visualization of the human head. A foreign body, 10 x 30 mm in size, partially protruded into the posterior ethmoidal cells and partially into the orbit, causing dislocation and compression of the medial rectus muscle and inferior rectus muscle. The other muscles and the optic nerve were intact. Various steps were taken to further the ultimate diagnosis and surgery. Thin CT sections of the nasal cavity, orbit and paranasal sinuses were made on a conventional CT device at a regional medical center, CT scans were transmitted via a computer network to different locations, and special views very similar to those seen on standard endoscopy were created. Special software for 3D modeling, specially designed and modified for 3D C-FESS purposes, was used, as well as a 3D-digitizer connected to the computer and multimedia navigation through the computer during 3D C-FESS. Our approach achieves the visualization of very delicate anatomical structures within the orbit in unconventional (non-standard) sections and angles of viewing, which cannot be obtained by standard endoscopy or 2D CT scanning. Finally, virtual endoscopy (VE) or a 'computed journey' through the anatomical spaces of the paranasal sinuses and orbit substantially improves the 3D C-FESS procedure by simulating the surgical procedure prior to real surgery.

The contribution deals vith application of virtual reality technology and computer assisted surgery in rhinology

One of the main objectives of our 3-dimensional (3D) computer-assisted functional endoscopic sinus surgery was to design a computer-assisted 3D approach to the presurgical planning, intraoperative guidance, and postoperative analysis of the anatomic regions of the nose and paranasal sinuses. Such an extremely powerful approach should allow better insight into the operating field, thereby significantly increasing the safety of the procedure. The last step to implementing the technology in the operating room was to connect the computer workstations and video equipment to remote locations by using a high-speed, wide-bandwidth computer network. During patient preparation, the surgeon in the operating room consulted remote experienced and skillful surgeons by viewing CT images and 3D models on computer workstations. The surgeon and consultants used software for CT image previews and 3D model manipulations on top of collaboration tools to define the pathosis, produce an optimal path to the pathosis, and decide how to perform the real surgical procedure. With tele-flythrough or tele-virtual endoscopy rendered through the use of 3D models, both surgeons can preview all the characteristics of the region (ie, anatomy, pathosis) and so predict and determine the next steps of the operation. This ensures greater safety thanks to the operation guidance and reduces the possibility of intraoperative error. The duration of the teleconsultation is thus shortened, which may prove the greatest benefit of tele-3D computer-assisted surgery. If this method were used, clinical institutions would spend less money for telesurgical consultation.