Diffusion weighted imaging for the detection and evaluation of cholesteatoma

Cholesteatoma is a collection of keratinous debris and stratified squamous epithelium. It is trapped in the middle ear and can lead to bony erosion. The disease is treated surgically often followed by a second-look procedure to check for residual tissue or recurrence. Cholesteatoma has specific signal-intensity characteristics on magnetic resonance imaging with very high signal intensity on diffusion weighted imaging (DWI). Various DWI techniques exist: Echo-planar imaging (EPI)-based and non-EPI-based techniques as well as new approaches like multi-shot EPI DWI. This article summarizes all techniques, discusses the significance in detecting cholesteatoma and mentions actual studies. Further recommendations for daily clinical practise are provided.

Utility of Non-EPI DWI MRI Imaging in Cholesteatoma: The Indian Perspective

The purpose of this prospective observational study was to evaluate the diagnostic performance of non-EPI-based techniques, in detecting both primary and residual/recurrent cholesteatoma in a tertiary care center. 56 patients (25 female and 31 male) aged between 6 and 59 years were prospectively evaluated for the presence or absence of cholesteatoma. This included both primary and postoperative recurrent cholesteatoma (16). All the patients underwent sequential CT scans of temporal bones and non-EPI DWI (Non-Echo Planar Diffusion-Weighted Imaging) MRI techniques. The findings were correlated with surgical findings regarding the presence or absence of cholesteatoma. The size of cholesteatoma that was diagnosed on non-EPI DWI MRI was measured. The smallest size was 6 mm and the largest one was 21 mm. The accuracy of non-EPI DWI MRI in diagnosing cholesteatoma (primary and recurrent) was 97.5%. Whereas in diagnosing recurrent cholesteatoma accuracy was 100%. Accuracy of non-EPI DWI MRI is very high in diagnosing cholesteatoma especially in recurrent cholesteatoma and can potentially replace second look surgery when intact canal wall techniques are used. The technique is best used with a CT Scan of the temporal bone to depict bony changes, anatomical variants, or complications. The combination of HRCT and non-EPI DWI needs to be employed in diagnosing primary and recurrent cholesteatoma to maximize the diagnostic benefit as they are complimentary.