CT Temporal Bones — Dictation, Appropriateness, and Dose for Residents

1. The High-Stakes Read: CT Temporal Bones

Outpatient CT Temporal Bones. 45-year-old with progressive conductive hearing loss, normal otoscopy. The ENT surgeon suspects otosclerosis but wants to rule out cholesteatoma or ossicular discontinuity. Your attending is going to want a millimeter-by-millimeter breakdown of the ossicular chain, the fissula ante fenestram, and the scutum. This isn’t a “look for the big stuff” scan; this is a microsurgical roadmap where every voxel counts. When I was a fellow, these were the reads that made me sweat — the anatomy is complex, the findings are subtle, and the clinical impact is huge. Getting the report right means the difference between a stapedotomy and a complex ossiculoplasty. For more high-yield guides like this, check out our free trainee calculators and references.

2. What a CT of the Temporal Bones Covers and What Attendings Look For

A high-resolution, non-contrast CT of the temporal bones is the definitive study for evaluating the bony structures of the ear. It provides exquisite detail of the ossicles, mastoid air cells, and inner ear labyrinth, which is essential for diagnosing the causes of conductive hearing loss and planning surgical interventions. Your attending expects a systematic, side-by-side comparison and a definitive statement on several key clinical questions.

Your report should confidently answer:

• Is there evidence of cholesteatoma (soft tissue with bone erosion, especially of the scutum or ossicles)?
• Is the ossicular chain intact (ruling out ossicular discontinuity) or fixed?
• Are there signs of otosclerosis (a hypodense focus at the fissula ante fenestram or involving the cochlea)?
• Is there superior semicircular canal dehiscence (SSCD)?
• What is the status of the mastoid air cells and middle ear (clear, opacified, sclerotic)?
• Are there any cochlear anomalies (e.g., Mondini malformation) or an enlarged vestibular aqueduct?
• In trauma, is there a temporal bone fracture, and is it longitudinal or transverse? Does it involve the facial nerve canal or otic capsule?

This isn’t the first choice for sensorineural hearing loss or suspected vestibular schwannoma—those are MRI questions. This is the workhorse for problems of bone and air.

3. Radiology Report Template for CT Temporal Bones

Here is a solid, structured template you can adapt for your macros. It forces a systematic review of all the critical structures.

Technique

High-resolution non-contrast helical CT of the temporal bones was performed with sub-millimeter axial acquisition. Axial, coronal, Pöschl, and Stenvers reformatted images were reviewed.

Findings

Right/Left Comparison: The temporal bones are symmetrically developed.

External Auditory Canals: The external auditory canals are patent bilaterally. No soft tissue abnormalities or bony erosion.

Middle Ear and Mastoids: The mastoid air cells and middle ear cavities are well-aerated. The tympanic membranes are not definitively visualized but appear intact without evidence of retraction. The scutum is sharp bilaterally. The ossicular chains are symmetric. The malleus and incus appear normal in configuration. The malleoincudal and incudostapedial joints are intact. The stapes superstructure is visualized.

Otic Capsule and Inner Ear: The cochlea demonstrates a normal 2.5 turns bilaterally. The vestibules and semicircular canals are normal in morphology. The vestibular aqueducts are normal in size (less than 1.5 mm at the midpoint). The bony covering of the superior semicircular canal is intact bilaterally. The fissula ante fenestram is normal in density without focal lucency.

Internal Auditory Canals and Nerves: The internal auditory canals are symmetric and normal in caliber. The facial nerve canals are traced from the IAC through the labyrinthine, tympanic, and mastoid segments and appear intact without evidence of fracture or dehiscence.

Adjacent Structures: The temporomandibular joints are unremarkable. The jugular bulbs are in their normal position and do not extend above the floor of the internal auditory canal. The sigmoid sinuses are patent.

Impression

1. Normal high-resolution CT of the temporal bones.
2. No evidence of cholesteatoma, otosclerosis, or superior semicircular canal dehiscence.
3. Intact ossicular chain bilaterally.

4. Free Template Sources for Your On-Call Toolkit

Building a personal macro library is a rite of passage. If you’re looking for more templates to build from, two great free repositories exist. The Radiological Society of North America (RSNA) curates a comprehensive library at RadReport.org, which covers a huge range of modalities. Another excellent resource is maintained by Australian radiologists at RadiologyTemplates.com.au. Both are solid, peer-reviewed sources for building out your toolkit.

5. The Next-Level Move: Free-Form Dictation to Structured Report

The template above is great, but what if you could just dictate the positive findings and have the normal structures filled in automatically? That’s the idea behind AI-powered reporting assistants. Instead of clicking through a structured template for every normal finding, you can dictate in free form—”Erosion of the scutum and long process of the incus on the right consistent with cholesteatoma”—and the software generates a complete, structured report. Tools like GigHz Precision AI are designed to streamline this process, taking your free-form positive findings and organizing them into ACR and SIR-compliant templates. It helps ensure every key element is addressed without the manual drudgery of navigating a complex macro, letting you focus on the pathology.

6. When Should You Order a CT of the Temporal Bones? ACR Appropriateness Criteria

Deciding between CT and MRI is a common clinical question. The American College of Radiology (ACR) provides evidence-based guidelines to help. For a CT of the temporal bones, the indications are quite specific.

Per the ACR’s guidelines on Hearing Loss and/or Vertigo, a non-contrast CT of the temporal bones is Usually Appropriate for the initial imaging of acquired conductive hearing loss when there’s no obvious mass on otoscopy. This is the classic scenario for evaluating otosclerosis or ossicular chain abnormalities. It’s also Usually Appropriate for surgical planning in cases of congenital hearing loss or for cochlear implant candidates. For mixed conductive and sensorineural hearing loss, it is also rated Usually Appropriate.

However, for purely acquired sensorineural hearing loss, an MRI of the internal auditory canal is the Usually Appropriate study to evaluate for retrocochlear pathology like a vestibular schwannoma. Similarly, for vertigo, MRI is generally preferred unless a bony cause like SSCD is specifically suspected.

In the context of trauma (Imaging of Facial Trauma), a CT is Usually Appropriate when there is clinical suspicion for a temporal bone fracture. For inflammatory conditions like cholesteatoma (Inflammatory Ear Disease), CT is the gold standard and is Usually Appropriate. For pulsatile tinnitus, a CT (often a CTA) is also Usually Appropriate as part of the initial workup to look for vascular or bony causes.

7. How Much Radiation Does a CT of the Temporal Bones Deliver?

Patients and referring clinicians are increasingly aware of radiation dose. A high-resolution CT of the temporal bones is a focused, low-dose study. The estimated effective dose is typically in the range of 1-2 mSv. To put that in perspective, it’s less than the average annual background radiation in the US (about 3 mSv) and is considered a low-dose exam by ACR standards.

The protocol is designed for high resolution in a very small area, which helps keep the overall dose low compared to larger body scans like a CT of the abdomen and pelvis. Technologists use a tight field of view and optimized parameters to maximize image quality while adhering to the ALARA (As Low As Reasonably Achievable) principle.

8. CT Temporal Bones Imaging Protocol — Phases, Contrast, and Reconstructions

A successful CT temporal bones study hinges on a meticulous technical protocol. Unlike a body CT, this is all about maximizing spatial resolution. The scan is performed without intravenous contrast for most indications. The key is acquiring sub-millimeter slices with a high-resolution bone algorithm and then creating specific reformats to evaluate key structures.

The Pöschl reformat, which is aligned along the long axis of the superior semicircular canal, is absolutely critical for diagnosing SSCD. Don’t sign off on a case without looking at it.

Common protocol pitfalls: The most common errors are using slices that are too thick (anything ≥1 mm will miss subtle ossicular erosion) or a field of view that is too wide (which degrades spatial resolution). Forgetting to generate the oblique Pöschl and Stenvers reformats is another major pitfall that can lead to a missed diagnosis of SSCD.

9. The 3-Months-Free Offer for Radiology Residents and Fellows

3+ months free for radiology residents and fellows.

Look like a rockstar on your reports — dictate positive findings in free form, and the AI generates a structured report using ACR + SIR templates with the appropriate clinical decision support firing automatically. All we ask in return is feedback so we can keep improving the product for trainees.

Signup is simple. No credit card, no long forms. To apply, just let us know:

1. Your PGY year (e.g., PGY-2, PGY-4)
2. Your training type (radiology residency or specific fellowship)
3. Your training program / hospital name

You can apply for the residents free-access program here and we’ll get you set up.

10. Frequently Asked Questions

Is it HIPAA-compliant?

Yes. The platform is designed for de-identified workflows by default. It processes the clinical content of your dictation without requiring patient identifiers, ensuring compliance with HIPAA privacy standards.

Do I need my hospital’s IT department to install anything?

No. The tool is browser-based and requires no local installation or special permissions from your IT department. It works on hospital workstations, your personal laptop, or even the call-room iPad.

How does this work with PowerScribe or other dictation systems?

It works alongside your existing dictation system. You can dictate your findings as you normally would, then use the tool to structure those findings into a complete report. You can then copy and paste the final, polished report back into your PACS/RIS.

Can I use this on my phone or an iPad?

Yes, the platform is web-based and responsive, so it’s accessible on any device with a modern web browser, including phones and tablets. This is perfect for reviewing a report or checking a template on the go.

Can I customize the templates?

Yes. While the system comes pre-loaded with standard ACR and society-level templates, you have the ability to customize them or create your own to match your personal preferences or your institution’s specific requirements.

What happens after I finish residency or fellowship?

The free access program is specifically for trainees. After you graduate, you can transition to a standard plan. We offer discounts for recent graduates to help you get started in your practice.