Imaging

Malignant Otitis Externa

Preliminary Diagnosis: Malignant Otitis Externa

I. What imaging technique is first-line for this diagnosis

  • CT temporal bone with and without contrast

II. Describe the advantages and disadvantages of this technique for diagnosis of malignant otitis externa.

Advantages

  • Relatively inexpensive, fast imaging modality

  • More specific and sensitive in evaluating the osseous structures for any evidence of erosion and destruction seen in otitis externa or temporal bone osteomyelitis

  • Better adept for detailing any involvement of the middle ear and inner ear osseous structures, specifically the ossicular chain, cochlea, and semicircular canals

Disadvantages

  • Exposes the patients to ionizing radiation

  • Less sensitive for detailing any subtle osseous edema or focal areas of enhancement

III. What are the contraindications for the first-line imaging technique?

  • May be contraindicated in pregnant patients

IV. What alternative imaging techniques are available?

  • MR imaging with and without contrast of the temporal bone and external ear

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of malignant otitis externa.

MR imaging with and without contrast of the temporal bone and external ear

Advantages

  • More specific and sensitive in detecting subtle enhancement and edema of the osseous structures signifying early inflammation or osteomyelitis not appreciated on CT imaging

  • May better detail any underlying or adjacent abscess

  • Does not expose patients to ionizing radiation

Disadvantages

  • Less adept in identifying the osseous structures and anatomy of the middle and inner ear

VI. What are the contraindications for the alternative imaging techniques?

MR imaging with and without contrast of the temporal bone and external ear

  • Contraindicated in patients with non-MR compatible hardware

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