Quantitative assessment of temporal bone anatomy on preoperative CT in acquired cholesteatoma: validation of current methods and correlation to outcomes after surgery

OBJECTIVE: 1. To identify methods of quantitative assessment of temporal bone anatomy on preoperative imaging in patients with primary acquired cholesteatoma. 2. To analyze the reproducibility of the identified methods. 3. To investigate whether quantitative assessment of temporal bone anatomy on preoperative imaging is correlated with recurrent or residual disease after cholesteatoma surgery. METHODS: 1. A literature review was performed. 2. External validation of the identified methods was achieved by investigating inter-rater reliability among three observers with varying otologic experience. 3. Methods were applied to CT scans of patients with primary acquired cholesteatoma and residual and/or recurrent disease (A), residual disease (B), or recurrent disease (C), and the results were compared with those of healthy controls (D). RESULTS: Ten methods were identified and 23 patients in each of groups A, B and C and 25 patients in group D were included. Acceptable agreement between observers was reached for 7/10 methods. No significant differences were found by more than one observer between cases with residual or recurrent disease and cases without recidivism. Significant differences between cases with (A, B, and C) and without (D) cholesteatoma were found by all three observers for measurements of mastoid ventilation and lateral-to-medial height of the tegmen. CONCLUSIONS: We identified 10 measurements of anatomical dimensions of the temporal bone on preoperative imaging in patients with acquired cholesteatoma, and seven of these methods reached acceptable agreement between observers. Agreement was more common between the more experienced observers. None of the studied characteristics correlated with residual or recurrent cholesteatoma after surgery. Identifying preoperatively available risk factors for residual or recurrent cholesteatoma can aid patient counseling, surgical decision making and cholesteatoma staging systems.