Quantitative Analysis of Temporal Bone Density and Thickness for Robotic Ear Surgery

Area of Science:

• Medical Imaging
• Surgical Planning
• Biomechanical Engineering

Background:

• Quantitative assessment of bone density and thickness via computed tomography (CT) is crucial for robotic ear surgery planning.
• Accurate preoperative data aids in optimizing surgical procedures and implant outcomes.

Purpose of the Study:

• To quantitatively assess temporal bone density and thickness using CT scans.
• To develop and validate novel indices for preoperative assessment of screw placement safety and mass distribution in robotic ear surgery.

Main Methods:

• Retrospective analysis of CT scans from cochlear implantation subjects (N=39) and ex-vivo specimens (N=15).
• Quantitative CT data obtained using a calibration phantom to estimate bone mineral density.
• Automated assessment of temporal bone thickness and cortical bone density using an anatomy-based coordinate system.
• Development of Screw Implantation Safety Index (SISI) and Column Density Index (CODI).
• Linear mixed-effects models used to analyze the effects of various factors on bone properties.

Main Results:

• Age, gender, and ear side showed negligible effects on bone thickness and density.
• Average cortical bone radiodensity was 1,511 Hounsfield units (1,145 mg HA/cm³).
• Bone thickness and density varied with distance from Henle's spine.
• SISI and CODI distributions identified safe screw placement areas and mass distribution patterns, with a local maximum observed posteriorly to the supramastoid crest.

Conclusions:

• Quantitative data on temporal bone density and thickness are provided for robotic and computer-assisted ear surgery.
• The proposed SISI and CODI indices enable patient-specific preoperative assessment for optimal screw placement and implant positioning.