Reliability of CT Scan in Assessing Soft Tissue Extension to the Oval and Round Windows in Chronic Otitis Media

Introduction: High-resolution CT scans have been used widely in the preoperative assessment of chronic otitis media. However, the literature reporting the reliability of CT scan in assessing the oval and round window is very limited.

Material and Method: Thirty-five patients with chronic otitis media were operated in our department and underwent preoperative high-resolution CT scan of the temporal bones. CT scanning consisted of axial and coronal planes with soft tissue windows at 2 mm slices. A comparison was undertaken between the radiological and intraoperative findings in the areas of oval and round window.

Results: The results revealed that: (1) from the 21 cases with CT-scan opacification due to soft tissue extension to the oval window, 10 cases (47.6%) were confirmed during surgery and in 11 cases (52.4%), the oval window was found during surgery to be disease free; (2) from the 14 cases without CT-scan opacification in the oval window, 6 cases (42.8%) were confirmed during surgery and in 8 cases (57.1%) the oval window was found to be occupied by cholesteatoma; (3) from the 17 cases with CT-scan opacification due to soft tissue extension to the round window, 8 cases (47%) were confirmed during surgery and in 9 cases (52.9%) the round window was found during surgery to be disease free; (4) from the 18 cases without CT-scan opacification in the round window, 16 cases (88.8%) were confirmed during surgery and in 2 cases (11.1%) the round window was found to be occupied by cholesteatoma. The sensitivity of CT-scan in predicting oval window soft tissue extension is 55% and the specificity 35%. The sensitivity of CT-scan in predicting round window soft tissue extension is 80% and the specificity 64%.

Conclusion: CT-scan is a rather unreliable method of assessing soft-tissue extension to the oval window and moderately reliable in assessing soft-tissue extension to the round window.