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CT
Head and NeckDemonstration data

CT Temporal Bones

High-resolution CT of the temporal bones provides sub-millimetre isotropic imaging of the middle and inner ear structures. Reconstructed with a sharp bone algorithm and multiplanar reformats, it is the primary modality for cholesteatoma, otosclerosis, ossicular pathology, temporal bone trauma and congenital anomalies.

Indications

  • Suspected acquired cholesteatoma with conductive hearing loss or otorrhoea
  • Conductive hearing loss for ossicular chain and otosclerosis evaluation
  • Sensorineural or mixed hearing loss with suspected otic capsule or inner ear anomaly
  • Temporal bone trauma with suspected fracture, ossicular disruption or CSF leak
  • Congenital hearing loss and cochlear implant candidacy assessment

Contraindications & Cautions

  • No absolute contraindication; ionising radiation dose considerations in children
  • Routine intravenous contrast is not required and generally not administered
  • MRI is preferred for retrocochlear pathology and residual/recurrent cholesteatoma characterisation

Patient Preparation

  • No specific patient preparation required
  • Remove earrings and metallic hair accessories to reduce artefact
  • Ensure head immobilisation to preserve high spatial resolution
  • Clarify laterality and specific clinical question before acquisition

Technique & Parameters

  • Non-contrast helical acquisition with ≤0.6 mm collimation and isotropic voxels
  • Reconstruction with a high-spatial-frequency (bone/sharp) kernel
  • Multiplanar reformats in axial and coronal planes at ~0.5-0.6 mm
  • Oblique Poschl (superior semicircular canal) and Stenvers reformats when indicated
  • Small field of view centred on each temporal bone for maximal detail

Systematic Review

  • Assess external auditory canal, tympanic membrane region and scutum
  • Evaluate ossicular chain (malleus, incus, stapes) integrity and alignment
  • Inspect the otic capsule, oval and round windows for lucency or fixation
  • Trace the facial nerve canal (labyrinthine, tympanic, mastoid segments)
  • Review tegmen tympani, mastoid air cells and semicircular canals

Key Findings & Significance

  • Cholesteatoma: non-dependent soft tissue in Prussak space with scutum erosion and ossicular destruction
  • Otosclerosis: lucency at the fissula ante fenestram (fenestral) and pericochlear otospongiosis (retrofenestral)
  • Ossicular disruption or dislocation, often incudostapedial, following trauma
  • Temporal bone fracture (otic-capsule sparing versus violating) and tegmen dehiscence
  • Semicircular canal dehiscence and congenital inner ear malformations (e.g. incomplete partition)

Differential Considerations

  • Cholesteatoma versus middle ear effusion, granulation tissue or cholesterol granuloma
  • Otosclerosis versus other causes of otic capsule lucency (e.g. osteogenesis imperfecta, Paget disease)
  • Glomus tympanicum/jugulare versus other middle ear soft-tissue masses
  • Traumatic ossicular disruption versus congenital ossicular anomaly
  • Automastoiditis with coalescence versus neoplastic mastoid involvement

Pearls & Pitfalls

  • Pars flaccida (attic) cholesteatoma classically erodes the scutum and displaces ossicles medially
  • A soft-tissue density eroding the lateral semicircular canal or facial nerve canal raises complication risk
  • Non-echo-planar diffusion-weighted MRI is complementary for detecting residual cholesteatoma
  • Distinguish otic-capsule-violating from otic-capsule-sparing fractures given prognostic implications

Structured Report

  • State laterality and correlate with audiometric and otoscopic findings
  • Describe soft-tissue location, ossicular integrity and bony erosion (scutum, tegmen, canals)
  • Report otosclerosis site (fenestral versus retrofenestral) when present
  • For trauma, classify fracture and note ossicular and facial canal involvement
  • Comment on surgically relevant anatomy (facial nerve course, tegmen dehiscence, sigmoid sinus position)

References

  • ACR-ASNR-SPR Practice Parameter for the Performance of CT of the Extracranial Head and Neck
  • Radiographics: Baráth K et al. Neuroradiology of Cholesteatomas
  • Radiographics: Purohit B et al. Imaging in Otosclerosis
  • Radiographics: Juliano AF et al. Imaging Review of the Temporal Bone

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.