Detection of Cholesteatoma Using Diffusion Magnetic Resonance Imaging

Detection of Cholesteatoma Using Diffusion Magnetic Resonance Imaging

Cholesteatoma is a retraction pocket lined with squamous epithelium lined with keratin debris occurring within pneumatized spaces of the temporal bone. Cholesteatomas have a propensity for growth, bone destruction, and chronic infection.High-resolution computerized tomography is the method of choice for imaging the middle ear .

In patients with recurrent cholesteatoma, computerized tomography can show the extent of cholesteatoma in relation to the ossicles and mastoid process,but computerized tomography has a high negative predictive value if neither a soft-tissue mass nor bony destructions are shown.However, if a soft-tissue mass in the middle ear is seen on computerized tomography, diagnosis of the mass is not possible because cholesteatoma, mucoid secretion, granulation tissue and cholesterol granuloma can not be differentiated from one another on computerized tomography.

Standard magnetic resonance imaging shows tissues better than computerized tomography,Therefore in patients with cholesteatoma, magnetic resonance imaging plays a complementary role to computerized tomography in the diagnostic workup, Although computerized tomography provides excellent Bony resolution for showing the anatomy, magnetic resonance imaging provides specificity in characterizing soft-tissue abnormalities shown on computerized tomography,How ever standard magnetic resonance imaging frequently fails to allow differentiation of cholesteatoma from other soft tissues or mucoid secretions, particularly in patients who had ear surgery.

Recent studies of diffusion weighted magnetic resonance imaging show that it is sensitive to cholesteatoma tissue.Recent studies highlights the ability of diffusion weighted magnetic resonance imaging in differentiating cholesteatoma from granulation tissue in patients who have undergone mastoidectomy and also these imaging modalities help in the diagnosis of residual cholesteatoma. Diffusion weighted magnetic resonance imaging play an important role in diagnosis of retraction pockets .

Diffusion weighted magnetic resonance imaging is based on the principle of random microscopic motion (Brownian motion) of water molecules.This "diffusion" of water molecules differs in each biological tissue, For example water molecules in cholesteatoma are less mobile giving rise to a hyper-intense signal, while in other tissues as granulation tissues, water molecules are more mobile thus appear less intense on diffusion weighted magnetic resonance imaging sequence.

Inclusion Criteria:

• • all patients presented with suspected primary cholesteatoma ,high risk retraction pockets ,Suspected recurrent or residual cholesteatoma after surgery .

Exclusion Criteria:

• Contraindication to magnetic resonance imaging (e.g., pacemaker, metallic implant,cochlear implant Or claustrophobia).