Fig 1.
Triplanar view mode of the conventional navigation system.
Fig 2.
Components of the augmented reality navigation system.
Nasal endoscopy imaging system: a. 0° endoscope, b. video converter, c. light source. Tracking system: d. infrared emission device, e and f. reflection markers fixed on the endoscope and the patient’s head. Workstation: g. the liquid-crystal display.
Fig 3.
Reflection marker fixed to the endoscope.
The marker allows for real-time lens tracking during surgery.
Fig 4.
3-D coordinates obtained by pointing to the piriform aperture vertex with the probe tip.
Table 1.
Description of the NASA-TLX rating scale [7].
Fig 5.
Display fusing the real nasal endoscopic images with 3-D virtual images in the head phantom experiment.
The center of the display shows the endoscopic image, and the surrounding background is the 3-D virtual image.
Fig 6.
Frequency distribution of target registration error (TRE) during the head phantom experiment.
Fig 7.
The augmented reality navigation system display during the cadaver head experiment.
After maxillary sinus expansion, ethmoidectomy, and frontal sinus expansion, a wide sphenoidotomy using an endoscopic endonasal approach was performed as the final part of the operation. Moreover, to provide sufficient exposure and maneuverability, the posterior nasal septum and middle turbinate were removed so that the classic intrasphenoid landmarks could be identified (A) involving the planum sphenoidale: OC, optic canal; mOCR, medial optico-carotid recesses; ICA, internal carotid artery; ST, sella turcica; and clivus. In addition, with image superimposition, we could observe the projection of certain anatomic structures on and around the endoscopic image, involving the A1 (black arrows) and A2 (black stars) segments of the anterior cerebral artery and internal carotid artery (black squares). In fact, these structures included any of concern to the surgeon, as long as they were segmented from the computed tomography (CT) image manually or automatically before the operation. (B) Bone in the left superior, posterior, and lateral walls of the sphenoid sinus was removed to expose the dura mater. As the lens moved forward, the projection of the bilateral internal carotid artery became much clearer. (C) After the dura mater was opened, the A1 and A2 segments of the anterior cerebral artery and left internal carotid artery were exposed; the actual locations were consistent with their projections, showing that the virtual and real images were fused accurately and moved synchronously. The AR-N system display expands the surgical field during nasal endoscopy both in terms of depth and breadth, and can thus provide surgeons with more intuitive information regarding anatomical structures.
Fig 8.
The target registration error (TRE) and the operation time (OT) for the augmented reality navigation (AR-N) system and conventional navigation (C-N) system.
The performances of the AR-N and C-N systems during the simulated operations were compared. (A) There was no significant difference between the systems in TRE (P > 0.05), (B) but a significant difference was found in OT (P < 0.05).
Table 2.
Performance of augmented reality navigation (AR-N) system and conventional navigation (C-N) system during the simulated operations.
Fig 9.
Reduction in operation time (OT) for the senior group compared with the junior group.
The average difference in the time required for surgery (OTC-N-OTAR-N) was compared, and there was a significant difference between the two groups (P < 0.05).
Fig 10.
Reduction in operation time (OT) due to use of the augmented reality navigation system according to years of surgical experience.
When we plotted the relationship between OTC-N-OTAR-N (on the vertical axis) and individual experience (on the horizontal axis), a trend toward a negative correlation was found.
Fig 11.
Differences in mental demand, physical demand, temporal demand, performance, effort, frustration level, and overall score between the two navigational systems.
The augmented reality navigation (AR-N) system outperformed the conventional navigation (C-N) system on all items (P < 0.05).
Fig 12.
Reduction in mental workload in the senior group compared with the junior group.
The average differences in the overall scores for mental workload during surgeries (SC-N-SAR-N) were compared, and there was a significant difference between the two groups (P < 0.05).
Fig 13.
Reduction in surgeons’ mental workload when using the augmented reality navigation (AR-N) system according to years of surgical experience.
When we plotted the relationship between SC-N-SAR-N (on the vertical axis) and individual experience (on the horizontal axis), a trend toward a negative correlation was found.