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3D Computer assisted surgery (CAS)

The greatest advance in the field of the nose and paranasal sinus surgery worldwide is functional endoscopic sinus microsurgery (FESS). The technique has many important advanteges over "old" surgical procedures of the region. Endoscopic operations are now performed with the use of "live image" via an endoscope. Video monitors, endo-micro cameras, and static two-dimensional (2D) black-and-white CT or MRI images are used. High-quality CT diagnosis provides extremely valuable information on anatomical relationships between paranasal sinuses and the surrounding structures, thus significantly improving the safety of FESS. However, in spite of its numerous advantages, such a 2D-head display has some shortcomings. Location of the endoscope relative to the target site presented on CT image cannot be quite precisely determined. Maximal concentration is therefore required from the surgeon, who has to rely on his own experience, occasionally merely on his intuition, to produce a real and visual advancement in the procedure. Therefore, it was necessary to develop a new approach in peri- and preoperative head imaging. The contribution of this system to surgery of the head has reflected in the development/use of computer programs for 3D display of the patient's head from 1994: perioperatively for proper timing of the operation and perioperatively for dynamic examination of the 3D projection of the head. This is an entirely new quality, especially in FESS, and the major advantage of the 3D C-FESS method. Operability of the anatomical regions of the head is determined by computer, thus making FESS really computer-assisted three-dimensional operations (3D C-FESS). By connecting surgical instruments to computer (i.e. robotic arm), and operating the computer and multimedia systems during the surgery, this new surgical approach has been further improved. During the 3D C-FESS method development, various program systems using volume-rendering techniques have been employed to create the operating field model. Initially, the modeling was performed using VolVis, Volpac/Vprender and GL Ware programs on a Silicon Graphics computer. With the development of 3D Viewnix V 1.0 software, we introduced them from the very beginning. Now we use 3D Viewnix V 1.1, T-Vox, Analyze, FreeFlight and OmniPro2 software. The use of software tools allowed us visualization of slices in sophisticated montage and cycle models. Multiple series can be simultaneously observed in various color tables at various magnifications. Series of images can be generated in various projections through the respective volume. We use slice segmentation for surface and volume rendering. Various entities can be modeled and stained with various dyes, their transparency can be modified and they can be observed as unified system. Manipulation with the generated models allows different views, shifts, sections, isolation, labeling and animation. On creating our 3D C-FESS approach in preoperative analysis of anatomical features and pathology and in planning future operations, some basic criteria were pre-set, including the use of computer-assisted surgical tools like in real OR. An adequate hardware has to be used in performing 3D C-FESS approach.

3D; Computer assisted surgery; CAS

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