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RD7.2 | Imaging in ENT — Practice Quiz
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A 5-year-old child has had a painful, discharging right ear for 8 weeks despite antibiotics. Over the last 48 hours the post-auricular region has become red, swollen and tender, pushing the pinna forward, and the child is now febrile. Otoscopy shows a sagging postero-superior canal wall. Which imaging investigation is most appropriate to confirm the suspected complication and plan surgery?
Correct. The picture is acute coalescent mastoiditis with a subperiosteal abscess complicating ASOM. HRCT temporal bone is the first-line study to demonstrate loss of mastoid air-cell septa (coalescence), cortical erosion and abscess; contrast-enhanced CT (or MRI) is added when intracranial extension (e.g. sigmoid sinus thrombosis, abscess) is suspected.
Image the complication, not the infection: ASOM is a clinical diagnosis, and imaging (HRCT temporal bone, with contrast CT/MRI for intracranial spread) is reserved for red flags such as mastoiditis, subperiosteal abscess, facial palsy, vertigo or intracranial signs.
ASOM and its complications are judged by what disease does to bone, so HRCT temporal bone is first-line. Plain mastoid X-rays are obsolete and insensitive; MRI IAM is for the cochlear nerve/CPA, not acute mastoid bone; ultrasound cannot assess the mastoid air cells; and the clinical red flags here mandate imaging rather than treating as simple AOM.
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A 30-year-old man with long-standing foul-smelling right ear discharge and a postero-superior attic perforation undergoes HRCT temporal bone. The radiologist reports a non-dependent soft-tissue mass in Prussak's space with blunting (erosion) of the scutum and erosion of the long process of the incus. Which diagnosis does this combination of findings most strongly support?
Correct. Non-dependent soft tissue (classically in Prussak's space), scutum blunting and ossicular (incus long-process) erosion are the hallmark HRCT features of acquired cholesteatoma — an expansile, bone-eroding keratin sac that defines unsafe CSOM.
On HRCT, cholesteatoma = non-dependent soft tissue (often Prussak's space) plus bony erosion (scutum blunting, ossicular erosion); this distinguishes unsafe CSOM from a benign dependent effusion and changes the surgeon's plan to mastoid exploration.
The key discriminator is bony erosion (scutum, ossicles) with non-dependent soft tissue. A simple effusion is dependent and erodes nothing; glomus tympanicum is a vascular promontory mass; otosclerosis causes otic-capsule lucency (fenestral/retrofenestral) not attic soft tissue; tympanosclerosis is calcific. The eroding non-dependent mass equals cholesteatoma.
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Two years after a canal-wall-up mastoidectomy for cholesteatoma, a patient is asymptomatic but the surgeon wants to exclude residual or recurrent disease before deciding on a second-look procedure. HRCT shows a small non-specific soft-tissue opacity in the mastoid cavity that could be cholesteatoma, granulation or fibrosis. Which investigation best distinguishes recurrent cholesteatoma from these mimics?
Correct. Non-EPI DWI MRI is the investigation of choice for detecting residual/recurrent cholesteatoma: keratin debris restricts diffusion and shows bright (high) signal, whereas granulation tissue and fibrosis do not. It can replace or defer a second-look operation.
Non-EPI diffusion-weighted MRI is the key problem-solving tool for cholesteatoma recurrence/residual disease — restricted diffusion (bright signal) flags keratin and can spare the patient a second-look mastoidectomy.
HRCT shows soft tissue but cannot tell cholesteatoma from granulation/fibrosis (all look the same), which is exactly the dilemma here. Non-EPI DWI MRI solves it because keratin restricts diffusion and lights up. Plain films are obsolete, bone scan is non-specific, and angiography is irrelevant.
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A 52-year-old woman reports gradual hearing loss in the left ear over a year with poor clarity on the telephone and occasional unsteadiness. Pure-tone audiometry shows a unilateral (asymmetric) sensorineural loss with disproportionately poor speech discrimination. Otoscopy is normal. Which imaging study is most appropriate?
Correct. Asymmetric/unilateral SNHL with poor speech discrimination and imbalance is a vestibular schwannoma until proven otherwise. Gadolinium-enhanced MRI of the IAM/posterior fossa is the gold standard, demonstrating an enhancing mass at the CPA/IAM (often with an 'ice-cream-cone' configuration).
Asymmetric SNHL = scan the nerve: gadolinium-enhanced MRI of the IAM/posterior fossa is first-line to exclude vestibular schwannoma at the CPA/IAM; CT (bone) does not characterise the cochlear nerve.
SNHL points to the nerve and soft tissue, which is the domain of MRI, not CT. HRCT images bone (congenital/otic-capsule problems); plain IAM films are obsolete; neck CT is irrelevant; and an asymmetric loss must be imaged, not simply observed, to exclude schwannoma.
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A 6-year-old boy has fluctuating, stepwise progressive bilateral sensorineural hearing loss, sometimes worsening after minor head bumps. The paediatric ENT surgeon suspects a congenital inner-ear (bony labyrinth) anomaly. Which imaging finding on HRCT temporal bone would best explain this presentation?
Correct. Enlarged vestibular aqueduct (EVA) is the commonest CT-detectable congenital cause of paediatric SNHL and characteristically produces fluctuating/stepwise loss that may worsen after minor head trauma. HRCT (bone) is the right modality to demonstrate the bony aqueduct and associated cochlear malformations.
In children with congenital SNHL, image the bone with HRCT: enlarged vestibular aqueduct (EVA) is the commonest CT finding and explains fluctuating/stepwise loss worsening after minor head trauma; MRI complements it for membranous/nerve detail and cochlear-implant planning.
Congenital bony-labyrinth anomalies are a CT (bone) question, and EVA is the classic finding causing fluctuating, trauma-sensitive paediatric SNHL. An enhancing IAM mass is a schwannoma; scutum erosion/non-dependent soft tissue is cholesteatoma; air-cell coalescence is mastoiditis; sclerosis indicates chronic disease — none explains this congenital picture.
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Before requesting a gadolinium-enhanced MRI of the IAM for a patient with asymmetric SNHL, which of the following is the most important safety consideration the clinician must check?
Correct. MRI has real contraindications — the clinician must screen for MRI-incompatible implants/devices (e.g. certain pacemakers, cochlear implants, ferromagnetic foreign bodies) and other contraindications (such as severe renal impairment limiting gadolinium) before ordering. Where MRI is contraindicated, CT may be used as an alternative.
MRI contraindications exist: always screen for MRI-incompatible implants/devices and other contraindications (e.g. renal impairment for gadolinium) before ordering an MRI IAM; CT is the fallback when MRI is unsafe.
The safety-critical step before any MRI is screening for MRI incompatibility (implants/devices) and contraindications. Fasting, a prior X-ray, an intact drum or prone positioning are not the governing safety issues; MRI contraindications genuinely exist and may force a CT alternative.
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