J Vet Sci.  2012 Dec;13(4):419-424.

Virtual otoscopy for evaluating the inner ear with a fluid-filled tympanic cavity in dogs

• Cho Y
• Jeong J
• Lee H
• Kim M
• Kim N
• Lee K

Abstract

The feasibility of virtual otoscopy (VO) imaging was evaluated in five dogs with experimentally induced otitis media, two control dogs, and two canine patients with otitis media. VO images of the tympanic cavity and ossicles were generated with commercially available software using raw computed tomography (CT) data. Eight out of 10 ears inoculated with pathogen exhibited obvious clinical signs associated with otitis externa. CT images revealed soft tissue density material occupying the tympanic bulla compatible with otitis media in three dogs with experimentally induced otitis media and two patients. No remarkable features were observed on the radiographs. Four different VO views (ear canal, tympanic bulla, eustachian tube, and ossicular chain) were created. Promontory, cochlea window, tympanic, and septum bulla as well as ossicles were easily and clearly distinguished except for the incus and stapes of the clinical patients. VO images were not more suitable than images created with conventional CT for accurately diagnosing otitis media in this study. However, it appears that VO could be more feasible for assessing the complex structure of the inner ear in dogs with fluid-filled tympanic cavities since fluid accumulation within the tympanic bulla did not affect the evaluation of bony tissue in the middle ear on VO images.

Keyword

computed tomography; dog; otitis media; virtual otoscopy

MeSH Terms

Animals
Blister
Cochlea
Dogs
Ear
Ear, Inner
Ear, Middle
Eustachian Tube
Incus
Otitis Externa
Otitis Media
Otoscopy
Stapes

Figure

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  Fig. 1 Transverse computed tomography (CT) image of the temporal bone with the dog in a dorsal recumbent position. Fluid opacity was seen around the tympanic bulla. The arrow within the circle shows the virtual otoscopy (VO) direction of Fig. 4. EC: ear canal, TB: tympanic bulla, M: malleus, I: incus, CW: cochlear window, D: dorsal, V: ventral, MED: medial, LAT: lateral.

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  Fig. 2 Transverse CT image of the temporal bone with the dog in a ventral recumbent position. Fluid level in the ventral aspect was observed in the tympanic bulla. The arrow within the circle shows the VO direction of Fig. 5.

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  Fig. 3 Transverse CT image of the temporal bone in a canine patient with otitis media placed in a ventral recumbent position. A fluid-filled tympanic bulla and an absence of air density in the ear canal were observed. The arrow within the circle shows the VO direction of Fig. 6.

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  Fig. 4 VO view from the tympanic bulla toward the auditory tube. Fluid opacity did not interfere with identifying the internal structures of the middle ear. S: stapes, P: promontory.

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  Fig. 5 VO view from the tympanic bulla toward the auditory tube.

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  Fig. 6 VO view from the tympanic bulla toward the auditory tube in the same dog shown in Fig. 5.

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