Objective: The aim of this study was to assess the accuracy of mass effect sign in the diagnosis of cholesteatoma at high-resolution computed tomography (HRCT).
Methods: This prospective study included 32 ears in 24 patients with chronic otitis media who underwent HRCT of the temporal bone. Otoscopic and operative notes were recorded. Image analysis was done both qualitatively and quantitatively. In the qualitative analysis, mass effect was evaluated visually by comparing both ears together in 4 certain anatomical sites. Ossicular erosions, erosion of tegmen tympani, erosion of tympanic segment of facial nerve canal, and the presence of lobulated nondependent opacity were also evaluated. In the quantitative analysis, we calculated the difference between the distances of the described anatomical sites in both ears.
Results: Qualitative analysis of mass effect sign showed 97.1% accuracy in detecting cholesteatoma. Ossicular erosions showed 69.2% accuracy in the diagnosis of cholesteatoma. In the quantitative analysis, we found that the cutoff point of 0.45 mm in the difference of aditus measure between both ears showed 85.3% accuracy in differentiating cholesteatoma from otitis media. The cutoff point of 0.75 mm in the differences in supratubal measure showed 86.1% accuracy. The cutoff point of 0.45 mm in the medial to incus measure showed 100% accuracy.
Conclusion: High-resolution computed tomography is highly valuable for the detection of mass effect sign, which has great importance in diagnosing cholesteatoma.