Imaging in ENT: which study for which question

Topic

CT shows bone, MRI shows soft tissue and nerves, ultrasound is the first look at a neck lump, PET-CT finds hidden cancer.

Updated Nov 12, 2026

See it in 3D: Temporal bones

Key points

Asymmetric sensorineural hearing loss or one-sided tinnitus: gadolinium MRI of the internal auditory canals (vestibular schwannoma).
Cholesteatoma: high-resolution temporal bone CT shows bone erosion; non-echo-planar diffusion-weighted MRI detects residual or recurrent cholesteatoma (bright signal).
Uncomplicated acute rhinosinusitis needs no imaging; suspected orbital or intracranial complication needs urgent contrast CT (and MRI).
Chronic rhinosinusitis: non-contrast CT of the sinuses after failed medical treatment or before endoscopic surgery.
Adult neck lump: ultrasound with fine-needle aspiration first; contrast CT or MRI for staging; PET-CT for unknown primary.
Necrotising otitis externa: CT for bone erosion and MRI for soft tissue spread; nuclear scans (technetium, gallium) show osteomyelitis activity and response.

What it is

Choosing the right study saves time, radiation and money. The basic rule is: computed tomography (CT) for bone and air (temporal bone, sinuses, fractures, deep neck abscess with contrast), magnetic resonance imaging (MRI) for soft tissue, nerves and the brain (vestibular schwannoma, skull base, perineural spread, intracranial complications), and ultrasound for superficial neck structures (lymph nodes, thyroid, salivary glands) and to guide fine-needle aspiration. PET-CT is used for staging cancer and searching for an unknown primary. Plain X-rays have a small role today. Many common problems, such as uncomplicated acute otitis or acute sinusitis, need no imaging at all.

Key facts

CT uses ionising radiation: avoid unnecessary scans in children and in pregnancy; use the lowest dose protocol that answers the question.
Iodinated contrast: ask about allergy, kidney function and metformin; MRI gadolinium: check kidney function.
MRI contraindications and cautions: some pacemakers and neurostimulators, metallic foreign bodies (especially in the eye), and cochlear implants (magnet; follow the device rules).
Temporal bone CT is the study for conductive loss with a normal eardrum when surgery is planned, for temporal bone fracture, congenital malformations and superior canal dehiscence.
PET-CT combines function (glucose uptake) and anatomy; false positives come from inflammation and early after radiotherapy.
Ultrasound-guided fine-needle aspiration is the first tissue test of a neck lump; open biopsy is left to the head and neck team.

Structure

Plain X-ray: soft-tissue lateral neck (retropharyngeal swelling, some foreign bodies), chest X-ray (aspirated foreign body, metastases), panoramic dental X-ray.
CT: temporal bone, sinuses, facial fractures, deep neck infection, cancer staging, CT angiography in trauma; cone-beam CT gives lower-dose bone images of sinuses, teeth and temporal bone.
MRI: internal auditory canal, cerebellopontine angle, skull base, nasopharynx, tongue and parotid, perineural spread, brain and venous sinuses (MR venography).
Ultrasound: neck nodes, thyroid, salivary glands, cysts; guides fine-needle aspiration; no radiation.
Nuclear medicine and PET-CT: staging and response of head and neck cancer, unknown primary, osteomyelitis of the skull base.
Contrast swallow studies: videofluoroscopy for swallowing, barium swallow for pharyngeal pouch and oesophageal lesions; angiography for vascular tumours and embolisation.

Clinical question and first imaging

Question	First study	Why
One-sided sensorineural hearing loss or tinnitus	Gadolinium MRI of the internal auditory canals	Shows schwannoma and nerve lesions
Cholesteatoma before surgery	High-resolution temporal bone CT	Bone erosion, ossicles, facial canal, tegmen
Recurrent cholesteatoma after surgery	Non-echo-planar diffusion-weighted MRI	Keratin restricts diffusion and looks bright
Otitis with fever, headache or neurological signs	Contrast CT of temporal bone and brain; MRI and MR venography	Abscess, sinus thrombosis, meningitis
Sinusitis with eye swelling or neurological signs	Contrast CT of sinuses and orbits (± MRI)	Orbital abscess, intracranial spread
Chronic rhinosinusitis before surgery	Non-contrast sinus CT	Surgical map of the sinuses
Adult neck lump	Ultrasound with fine-needle aspiration	Characterises the node and takes cells
Deep neck infection	Contrast CT of the neck	Abscess versus cellulitis, airway, spread
Unknown primary or advanced cancer staging	PET-CT	Finds the primary and distant disease
Pulsatile tinnitus with a retrotympanic mass	Temporal bone CT and MRI (± angiography)	Paraganglioma versus vascular anomaly

In clinical practice

Ordering CT for uncomplicated acute sinusitis, where findings overlap with the common cold.
Doing an open biopsy of a neck lump before imaging and fine-needle aspiration.
Using CT instead of MRI to look for a vestibular schwannoma: small tumours can be missed.
Forgetting that a normal CT does not exclude a posterior fossa stroke in acute vertigo; diffusion-weighted MRI is needed.

Next step / Initial management

Start with the clinical question, then choose: CT for bone and air, MRI for soft tissue and nerves, ultrasound for the superficial neck, PET-CT for cancer staging.
No routine imaging for uncomplicated acute otitis media, otitis externa or acute rhinosinusitis; treat clinically and image only if complications or red flags appear.
Suspected complication of otitis or sinusitis (orbital swelling, neurological signs, mastoid swelling): urgent contrast CT and same-day referral to ENT.
Asymmetric sensorineural loss: MRI and priority referral to ENT; persistent adult neck lump: ultrasound with fine-needle aspiration and urgent referral to head and neck surgery (cancer pathway).

Test yourself

Think of the answer, then tap the question to see it.

A 50-year-old has progressive left sensorineural hearing loss and left tinnitus. Which imaging study?

Gadolinium-enhanced MRI of the internal auditory canals to look for a vestibular schwannoma.

One year after canal-wall-up surgery for cholesteatoma, which study detects residual disease without reopening the ear?

Non-echo-planar diffusion-weighted MRI, in which cholesteatoma appears bright.

A child with sinusitis develops eyelid swelling, painful eye movements and proptosis. Which study?

Urgent contrast CT of the sinuses and orbits to look for a subperiosteal or orbital abscess, with same-day ENT and ophthalmology referral.

What is the first-line investigation of a persistent lateral neck lump in an adult?

Neck ultrasound with fine-needle aspiration, followed by CT or MRI and, if the primary is not found, PET-CT; open biopsy only by the specialist.

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See it in 3D1

The structures of Durgical's 3D anatomy where it is found.

Temporal bones

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Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.

Sources: Appropriate Magnetic Resonance Imaging Ordering (StatPearls Publishing (NCBI Bookshelf), 2025); Computed Tomography Safety (StatPearls Publishing (NCBI Bookshelf), 2023); Magnetic Resonance Imaging (MRI) Safety and Biological Effects (StatPearls Publishing (NCBI Bookshelf), 2026); Nuclear Medicine PET/CT Head and Neck Cancer Assessment, Protocols, and Interpretation (StatPearls Publishing (NCBI Bookshelf), 2026); Fine Needle Aspiration (StatPearls Publishing (NCBI Bookshelf), 2022); Dental Cone Beam Computed Tomography (StatPearls Publishing (NCBI Bookshelf), 2023); Acute Sinusitis (StatPearls Publishing (NCBI Bookshelf), 2025); Middle Ear Cholesteatoma (StatPearls Publishing (NCBI Bookshelf), 2024); Necrotizing (Malignant) Otitis Externa (StatPearls Publishing (NCBI Bookshelf), 2023).

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