###### Abstract  
(1) Background: The purpose of this study was to develop an image-guided endoscopic sinus surgery (IGESS) system, named Mediator(r), based on the leave-one-out registration strategy and three-dimensional (3D) volumetric visualization of the nasal cavity and paranasal sinuses. (2) Methods: A phantom was designed and fabricated using a 3D printer. We then performed a phantom-based accuracy evaluation to validate the performance of the developed registration method. We included 11 patients who underwent IGESS for clinical study to compare the performance of the developed IGESS system with that of a commercialized system. (3) Results: The fiducial registration error (FRE) was 0.14 mm, and the target registration error (TRE) was 0.82 \(\pm\) 0.50 mm by the phantom-based evaluation. As a result of the clinical comparative study, the average registration times were 36.04 \(\pm\) 4.7 and 89.35 \(\pm\) 26.1 s for the developed and commercialized systems, respectively (\(p\) < 0.05). The image loading time of the developed system was also shorter than that of the commercialized system (\(p\) < 0.05). The average accuracy score of the developed system was not significantly different from that of the commercialized system (\(p\) > 0.05). (4) Conclusions: The developed system provided an accurate point-to-point registration method based on the leave-one-out strategy. According to the results of the clinical comparative study, we demonstrated that the developed system showed reliable potential for clinical application.  
image-guided endoscopic sinus surgery; 3D volumetric visualization; phantom-based evaluation; clinical comparative study +
Footnote †: journal: Applied  
dimensionally rendered virtual models are continuously visualized on the screen of the system to provide visual perceptions of the internal anatomy of the patients during surgery [3; 4; 5; 6; 7]. IGS systems require accurate positioning of the surgical instruments or target anatomical structures [2]. Accuracy of the IGS systems is closely related to registration between the patient's physical space and the image space [6; 7; 8]. Point-to-point registration using a corresponding pair of fiducial markers, such as non-invasive adhesive markers, invasively implanted markers, or anatomical landmarks, is commonly used for IGS systems [9; 10; 11; 12; 13; 14]. In ESS using an IGS system, point-to-point registration methods use anatomical fiducials on the facial skin of patient [8]. To date, since there are no systematic criteria for evaluating registration accuracy, researchers have used non-standardized methods to evaluate it.  
An electromagnetic (EM) tracking-based IGS system has no line-of-sight problem, so it can be used in minimally invasive surgeries and especially in ESS [15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25]. By using the transmitted information, the position and orientation of the tracking tool are calculated to visualize their locations during surgery. In ESS, the current position of the pointing tool is visualized on the screen of the IGS system.  
The contribution of this work is four-fold: (1) We developed a point-to-point registration method based on the leave-one-out strategy. (2) We fabricated a phantom for evaluating the accuracy of the image registration method according to ASTM F2554-10 [26]. (3) We developed an image-guided endoscopic sinus surgery (IGESS) system named Medigator(r) (Gmeditec, Incheon, Korea) by providing 3D volumetric visual perception of patient internal anatomy. (4) We performed clinical studies to compare the developed IGESS system with a commercialized system (Scopis(r) Hybrid Navigation System, Stryker, Kalamazoo, MI, USA).