Virtual Endoscopy of the Paranasal Sinuses Using Perspective Volume Rendered Helical Sinus Computed Tomography

Abstract

Our goal was to use three-dimensional information obtained from helical computed tomographic (CT) data to explore and evaluate the nasal cavity, nasopharynx, and paranasal sinuses by simulated virtual endoscopy (VE). This was done by utilizing a new image reconstruction method known as perspective volume rendering (PVR). Thin-section helical CT of the nasal cavity, nasopharynx, and paranasal sinuses was performed on a conventional CT scanner. The data were transferred to a workstation to create views similar to those seen with endoscopy. Additional views not normally accessible by conventional endoscopy were generated. Key perspectives were selected, and a video "flight" model was choreographed and synthesized through the nasal cavity and sinuses based on the CT data. VE allows evaluation of the nasal cavity, nasopharynx, and paranasal sinuses with appreciation of the relationships of these spatially complex structures. In addition, this technique allows structural visualization with unconventional angles, perspectives, and locations not conventionally accessible. Although biopsies, cultures, and lavages routinely done with endoscopy cannot be performed with VE, this technique holds promise for improving the diagnostic evaluation of the nasal cavity, the nasopharynx, and the paranasal sinuses. The unconventional visual perspectives and very low morbidity may complement many applications of simple diagnostic endoscopy.

The paranasal sinuses: three-dimensional reconstruction, photo-realistic imaging, and virtual endoscopy

“…It is an utterly non-invasive and safe method in which we could examine paranasal sinuses by using high-quality images. Furthermore, It allowed access to places inaccessible to conventional endoscopy [9,22]. The surgical procedure can be repeated ad libitum on this method.…”

Virtual endoscopic environments in modern neurosurgical practice

“…The accuracy and reproducibility of 3-D rendering techniques in the visualization of both normal and abnormal anatomy needs to be established. [14,45,46] Clinically, an additional potential issue is the cost effectiveness of virtual endoscopy and the issue of whom should be completing these studies. The issue of professional sovereignty regarding this technology will obviously become a question of interest between radiologists, neurologists, and neurosurgeons in the near future.…”

“…[14] The imaging data were transferred to an Onyx workstation by utilizing the Reality Engine II Graphics package (Silicon Graphics). [14] Image processing was performed with a VoxelView software version 2.1.2 (Vital Images, Fairfield, IA). Noncontributory data was disposed of using a technique termed "histogram truncation and compression," thereby conserving disc space.…”

Virtual Endoscopy of the Nasal Cavity and the Paranasal Sinuses

“…The latter is defined as a volume element (Rogalla et al, 2000) or the smallest distinguishable volume part of a 3D space. These individual voxels merge to create the three-dimensional model, analogous to a two-dimensional image formed by pixels (Gilani et al, 1997).…”