Transcanal Computed Tomography Views for Transcanal Endoscopic Lateral Skull Base Surgery: Pilot Cadaveric Study

Area of Science:

• Otolaryngology
• Neurosurgery
• Medical Imaging

Background:

• Transcanal endoscopic approaches offer minimally invasive access to the lateral skull base.
• Conventional computed tomography (CT) imaging planes (axial and coronal) are not optimized for the transcanal surgical corridor.
• Improved preoperative imaging is needed for enhanced surgical planning and navigation.

Purpose of the Study:

• To describe and validate a novel CT-based "transcanal view" for preoperative planning and intraoperative navigation in endoscopic lateral skull base surgery.
• To compare the utility of the transcanal view with traditional axial and coronal CT reformats for visualizing key anatomical structures within the external auditory canal (EAC).

Main Methods:

• High-resolution CT scans (0.625 mm slice thickness) were performed on six cadaveric temporal bones.
• Three-dimensional (3D) Slicer software was used to create reformatted "transcanal" views aligned with the plane of the EAC.
• Measurements were taken to compare distances between critical anatomical landmarks in the transcanal view versus traditional axial and coronal views.

Main Results:

• The optimal oblique tilt for the transcanal CT reformats was determined to be 6.67° ± 1.78°.
• Critical landmarks, including the annulus, isthmus, stapes capitulum, and mastoid facial nerve, were easily identified using the transcanal view.
• Specific mean measurements were obtained for the annulus diameter, isthmus diameter, and distances between key structures and the EAC length.

Conclusions:

• This study presents the first description of a novel "transcanal" CT sequence specifically designed for endoscopic lateral skull base surgery.
• The transcanal view facilitates improved visualization and measurement of anatomical structures crucial for surgical planning.
• Further research is warranted to explore the impact of incorporating this transcanal CT reformat into surgical decision-making processes.