Preliminary Diagnosis: Acute Labyrinthitis
I. What imaging technique is first-line for this diagnosis?
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CT temporal bone without contrast
II. Describe the advantages and disadvantages of this technique for diagnosis of acute labyrinthitis.
Advantages
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Relatively inexpensive, fast imaging modality compared with MRI
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Better able to assess the osseous structures for any bone erosion to suggest an inflammatory or infectious process
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The cochlea, semicircular canals, utricle, and vestibule, which are all inner ear structures, are well identified on CT scanning.
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Better to evaluate the ossicular chain of the middle ear for any extension of inflammatory process into the middle ear compared with other imaging modalities
Disadvantages
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Exposure to ionizing radiation
III. What are the contraindications for the first-line imaging technique?
CT scanning may be contraindicated in pregnant patients.
IV. What alternative imaging techniques are available?
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MRI with and without contrast of the brain, internal auditory canal, and inner ear may be performed.
V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of acute labyrinthitis.
Advantages
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May identify subtle edema or focal areas of abnormal enhancement within the inner ear structures not identified on the CT of temporal bone
Disadvantages
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MRI is far less adept at evaluating the adjacent osseous structures.
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May be subject to susectibilty weighted artifact or motion artifact
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Requires significant patient cooperation
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Expensive
VI. What are the contraindications for the alternative imaging techniques?
Contraindicated in patients with non-MR-compatible hardware.
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