Agreement between HRCT Imaging and Intraoperative Measurements in Predicting Stapedotomy Prosthesis Length in Otosclerosis Patients

Abstract

Introduction: This study aimed to evaluate the accuracy of preoperative high-resolution computed tomography (HRCT) imaging in measuring the distance from the long process of the incus to the footplate and its potential for predicting the optimal prosthesis length required for stapedotomy in patients with otosclerosis.

Materials and methods: This cross-sectional study included fifty patients scheduled for primary stapedotomy. A radiologist obtained and reconstructed preoperative HRCT scans of the temporal bone to measure the distance from the long process of the incus to the oval window in both axial and coronal views. These HRCT-derived measurements were then compared with intraoperative measurements performed by an otolaryngologist. The agreement between the two methods was assessed using correlation and Bland-Altman analysis.

Results: The mean distances measured by HRCT and intraoperatively were 4.15mm and 4.27mm, respectively. A strong and statistically significant correlation (r=0.928, P<0.001) was observed between the two approaches, indicating a robust association. The Bland-Altman analysis revealed a mean bias of 0.11±0.07mm, with limits of agreement (LoAs) ranging from -0.02 to 0.26 mm, and no points exceeding the 95% LoAs. The maximum potential error between the two measurement methods was 0.28mm, suggesting that HRCT imaging can reliably predict prosthesis length. In a stratified analysis based on the surgical distance (≤4 mm [N=11], 4.25mm [N=25], ≥4.5mm [N=13]), good agreement was maintained in the Bland-Altman analysis.

Conclusion: Preoperative HRCT imaging may be a valuable tool for accurately predicting the required prosthesis length prior to stapedotomy in otosclerosis patients.

Keywords: CT scan; Otosclerosis; incus bone; stapedotomy.

Fig 1

HRCT Imaging measuring a long process of incus to oval window

Fig 2

Scatter plot of correlation between CT scan and surgical measurements of long process-footplate distance

Fig 3

Bland-Altman plot for agreement analysis between preoperative HRCT Imaging and Intraoperative Measurements. Bias is shown as solid red line with 95% confidence intervals as dashed lines.

Fig 4

Bland-Altman plot for agreement analysis between preoperative HRCT Imaging and Intraoperative Measurements in subgroups based on the surgery score. A) Patients with a score ≤ 4 mm, B) patients with a score of 4.25 mm, and C) patients with a score ≥ 4.5 mm. Bias is shown as solid red line with 95% confidence intervals as dashed lines.