Value of high-resolution computed tomography and magnetic resonance imaging in the detection of residual cholesteatomas in primary bony obliterated mastoids.

PURPOSE The objective of this study was to assess the value of high-resolution computed tomography (HRCT) and that of magnetic resonance imaging (MRI), including postcontrast T(1)-weighted images and echo-planar diffusion-weighted (EP-DW) images, in the detection of residual cholesteatomas after primary bony obliteration of the mastoid. PATIENTS AND METHODS Twenty-three patients underwent a second-look surgery 8 to 18 months after they underwent a primary bony obliteration technique. All patients were evaluated by HRCT and MRI before their second-look surgery. A retrospective analysis was performed. RESULTS A residual cholesteatoma was found in 2 of the 23 patients; both cases of cholesteatoma had a diameter less than 4 mm. In these 2 patients, residual cholesteatoma was found in the middle ear cavity and not in the obliterated mastoid. In all cases, HRCT showed a homogeneous obliteration of the mastoid cavity. On MRI, only one cholesteatoma pearl was detected using contrast-enhanced T(1)-weighted imaging. Findings from the EP-DW imaging were negative for all cases. CONCLUSION This study demonstrates that HRCT is still the imaging technique of choice for the evaluation of bony obliterated mastoids. It shows the low sensitivity and specificity of HRCT for the characterization of an associated opacified middle ear and those of contrast-enhanced T(1)-weighted imaging and EP-DW imaging for the detection of small residual cholesteatomas after primary bony obliteration.