Biometry of the normal stapes using stapes axial plane, high-resolution computed tomography

Area of Science:

• Otolaryngology
• Medical Imaging
• Anatomy

Background:

• The stapes, a crucial ossicle in the middle ear, presents challenges for computed tomography (CT) analysis due to its small size and oblique orientation.
• Identifying an optimal imaging plane is essential for accurate stapes assessment.

Purpose of the Study:

• To determine the optimal axial plane for CT imaging of the stapes, parallel to its superstructure.
• To assess the positional relationship of this stapes axial plane relative to the conventional lateral semicircular canal plane.
• To measure key dimensions of the stapes, including length, width, and footplate thickness.

Main Methods:

• A retrospective analysis of 208 computed tomography scans from normal ears was performed.
• Measurements included stapes length and width, footplate thickness, and incudostapedial joint width.
• The orientation of the stapes axial plane was compared to the lateral semicircular canal plane.

Main Results:

• The optimal stapes axial plane was found to be oriented upward, outward (44°), and forward (12°) relative to the lateral semicircular canal plane.
• Mean measurements included head-to-footplate distance (3.7 mm), superstructure width (2.7 mm), and footplate thickness (0.27 mm on stapes plane vs. 0.48 mm on lateral semicircular canal plane).
• Incudostapedial joint width was consistently below 0.7 mm.

Conclusions:

• The stapes axial plane, oriented as described, yields measurements closely approximating anatomical data.
• This plane is particularly accurate for assessing stapes footplate thickness.
• These findings can improve the diagnostic utility of CT scans for stapes evaluation.