Diffusion-weighted MR imaging for evaluation of pediatric recurrent cholesteatomas

Objective: To compare the efficiency of diffusion-weighted MR imaging (MRI) vs. high resolution CT in predicting recurrent or residual cholesteatoma in children who underwent prior middle ear surgery.

Design: Prospective study.

Setting: Tertiary care university hospital.

Patients: Seventeen patients (4 with 2 recurrences) aged 5-17 years (mean 11.4) previously surgically treated for a cholesteatoma of the middle ear, were included for follow-up with systematic CT scan and MRI, between 2005 and 2007.

Methodology: CT scan was performed on a Siemens Somaton 64 (0.5/0.2 mm slices reformatted in 0.5/0.3 mm images), parallel and perpendicular to the lateral semi-circular canal for each ear (100 mmx100 mm FOV). MRI was undertaken on a Siemens Avanto 1.5 T unit, with an adapted protocol for young children. Diagnosis of recurrent cholesteatoma was based on the evidence of a hyperintense image at B1000 on diffusion-weighted images. Results of CT scan and MRI were compared with operative diagnosis.

Results: Nine patients had a positive MRI, among which 8 had cholesteatoma confirmed during revision surgery. In the 12 negative MRI cases, 5 were positive on revision surgery. None of these lesions was over 3mm. Two of them were diagnosed on the CT scan. CT scan alone had a positive predictive value of 75%, and a negative predictive value of 58%.

Conclusion: Diffusion-weighted MRI is associated with a high positive predictive value for the detection of recurrent cholesteatoma. CT scan remains the first choice imaging technique. In case of doubtful CT scan, diffusion-weighted MRI could confirm a recurrence or, when negative, avoid second-look surgery.