MRI IAM — with gadolinium
As for the unenhanced screen, with thin post-contrast T1 through both internal auditory canals and the labyrinth.
Typical, not policy
Timings, volumes and delays here are representative values drawn from published guidance. Scanner generation, injector, cardiac output and local preference all move them. Confirm against your department's own protocol before you rely on a number.
When to use it
- Sudden sensorineural hearing loss where intralabyrinthine pathology is suspected and the unenhanced study is normal.
- Suspected labyrinthitis or neuritis of the eighth nerve.
- Post-operative surveillance after vestibular schwannoma surgery or radiosurgery, where scar and residual tumour must be separated.
- A lesion seen on the unenhanced screen that needs characterising.
- Suspected facial nerve pathology extending along the labyrinthine or tympanic segments.
Technique
- Thin-section post-contrast T1, typically 2 mm or less, with fat saturation where the petrous marrow or parotid region is relevant.
- The unenhanced 3D heavily T2-weighted acquisition is retained: it provides the anatomical map that the enhanced series is read against.
- A matched unenhanced thin T1 is needed to distinguish enhancement from intrinsic high signal such as haemorrhage.
Where it goes wrong
- Adding contrast reflexively for every hearing-loss referral, which increases cost and exposure with little diagnostic yield in the screening population.
- Failing fat saturation at the skull base, producing bright signal that is misread as enhancement.
- Omitting a matched unenhanced T1, so intralabyrinthine haemorrhage is called enhancement.
Clinical questions that reach this study
Contrast
Gadolinium, intravenous
Macrocyclic gadolinium agent at a typical single dose of about 0.1 mmol/kg; thin-section post-contrast T1 through the canals and labyrinth.
Acquisition
- Breathing
- Free breathing.
- Preparation
- Include the audiogram result and the side of the symptom — a bilateral symmetrical loss is a different question. Contrast is added only for specific sub-questions; do not assume it. Cochlear implants and some middle-ear prostheses need explicit device-conditionality checking before booking.
Safety checks this protocol carries
Derived from the contrast agent and phases above, not authored here — which is why they cannot drift apart from what the protocol actually does.
- MR safety screening for implants and foreign bodies· radiographer at scan