What type of MRI (Magnetic Resonance Imaging) and location are recommended for a patient with hearing loss?

MRI with Dedicated Internal Auditory Canal Protocol for Hearing Loss

For patients with hearing loss, an MRI with dedicated Internal Auditory Canal (IAC) protocol is the recommended imaging study of choice.

Optimal MRI Protocol

The MRI should include:

• High-resolution 3D T2-weighted sequences (such as CISS, FIESTA, SPACE, or DRIVE)
• Thin sections across the IAC and inner ear (submillimeter preferred)
• Evaluation of the brainstem and thalami
• With and without gadolinium contrast 1, 2

This protocol provides the highest diagnostic yield for patients with hearing loss, with pathological findings directly related to hearing loss detected in 7-13.75% of cases 1.

Rationale for MRI IAC Protocol

MRI is superior to other imaging modalities for several key reasons:

• Gold standard for detecting vestibular schwannomas (acoustic neuromas) 1
• Can identify other causes of hearing loss including:
  • Inflammatory changes (labyrinthitis, neuritis)
  • Demyelinating processes (multiple sclerosis)
  • Vascular abnormalities
  • Cochlear inflammation 1, 3

Role of Contrast

While contrast administration can facilitate visualization of inflammatory changes and neoplasms 1, recent evidence suggests high-resolution T2-weighted imaging alone may be sufficient for screening:

• Non-contrast high-resolution T2WI can detect intralabyrinthine schwannomas with 84-100% sensitivity 4
• This may reduce costs, time, and adverse events associated with gadolinium administration

However, the American College of Radiology still recommends contrast for comprehensive evaluation 1, 2.

When to Consider CT Temporal Bone

CT of the temporal bone should be considered as a complementary study or alternative in specific situations:

• When MRI is contraindicated (pacemakers, metallic implants, claustrophobia)
• For suspected otospongiosis (a common cause of mixed conductive and sensorineural hearing loss)
• For evaluation of bony abnormalities such as:
  • Superior semicircular canal dehiscence
  • Temporal bone fractures
  • Ossicular chain abnormalities 1, 2

What Not to Order

The following studies are not supported by evidence for isolated hearing loss:

• MR Angiography (MRA) Head
• MR Venography (MRV) Head
• CT Head (less sensitive than MRI for retrocochlear pathology)
• CTA Head 1

Clinical Pearls

• All patients with sudden sensorineural hearing loss should be evaluated for vestibular schwannoma, regardless of associated diseases or audiometric pattern 1
• MRI has the highest yield of any diagnostic test for sudden sensorineural hearing loss 1
• For patients unable to undergo MRI, a fine-cut CT of temporal bones with contrast may be used as an alternative 1
• Auditory Brainstem Response (ABR) testing is less sensitive than MRI, particularly for small tumors (8-42% sensitivity for tumors <1cm) 1

Remember that early detection of underlying causes can significantly impact treatment decisions and outcomes, particularly for conditions like vestibular schwannomas where early intervention may preserve hearing and reduce treatment complexity.