Semi-Automated Virtual Endoscopy of the Frontal Recess.

Introduction: Virtual endoscopy (VE) is the computer-based reprocessing of diagnostic imaging to simulate endoscopy of an anatomic region of interest. VE of the Frontal Sinus Outflow Tract (FSOT) may assist surgical planning and education.

Method: VE was performed on 16 normal sinus computed tomography (CT) scans for a total of 32 sides using the "path-to-target" tool on the TruDi surgical navigation system (ver. 2.3; Acclarent, Irving, CA, USA). To aid orientation during VE, planning points were placed on the middle turbinate, ethmoidal bulla, and skull base. The VE representation of anatomy and FSOT accuracy was manually confirmed by reviewing the corresponding orthogonal CT images and comparing them to the computed pathway.

Results: Of the 32 sides, the software successfully calculated the FSOT in 22 sides (69%). Of those 22 sides, the calculated FSOT, depicted in the VE sequences accurately represented the FSOT. Among sides with an accurately calculated FSOT, the VE sequences depicted a "fly-through" from a starting point in the middle meatus around various frontal recess cells to the end point in the frontal sinus.

Conclusion: This pilot study demonstrates that software-generated VE of the FSOT is indeed feasible but requires confirmation by the surgeon for accuracy. Instances in which the software did not achieve its objective may drive further refinements of the protocol. VE of the FSOT should be explored as a tool for preoperative planning and surgical education.