CT Stroke Protocol (CT + CTA + CTP) — Dictation, Appropriateness, and Dose for Residents

1. The Stroke Alert Hits: From Door to Dictation in Minutes

The overhead speaker crackles: “Stroke Alert, CT 1.” It’s a stat CT Stroke Protocol from the ED. The patient is on the table, and the clock is ticking—door-to-needle time is a core quality metric, and your read is the critical gatekeeper for treatment. The stroke neurologist and IR attending are waiting for three numbers from you: Is there a bleed? Is there a Large-Vessel Occlusion (LVO)? And what are the core and penumbra volumes? Getting this right, and getting it fast, is the job.

When I was a fellow, the pressure of a stroke read was intense. You have to synthesize three separate studies—non-contrast, angiography, and perfusion—into a single, actionable report. There’s no time to look up the DEFUSE-3 criteria. This guide breaks down the complete CT Stroke Protocol into a systematic approach, giving you a rock-solid template so you can focus on the findings, not the formatting. For more high-yield guides like this, check out the residents and fellows resource hub.

2. What a CT Stroke Protocol Covers and What Attendings Look For

The comprehensive CT Stroke Protocol is a three-part imaging series designed to answer a cascade of critical questions in the hyperacute stroke setting. Each component builds on the last, guiding the decision for intravenous thrombolysis (tPA) or mechanical thrombectomy. Your attending expects a report that addresses each part systematically.

Here’s what you need to evaluate and report:

• Non-Contrast CT (NCCT) Brain: This is the first and most crucial step. The primary goal is to rule out intracranial hemorrhage, which is an absolute contraindication to tPA. You’ll also assess for early ischemic changes using the Alberta Stroke Program Early CT Score (ASPECTS), a 10-point scale evaluating the middle cerebral artery (MCA) territory. An ASPECTS of ≥6 often supports thrombectomy candidacy. Look for a hyperdense MCA sign, an early indicator of a large thrombus.
• CT Angiography (CTA) Head and Neck: Performed immediately after the NCCT, the CTA identifies the presence and location of a large-vessel occlusion. This is the roadmap for the interventionalist. You must evaluate the vessels from the aortic arch to the circle of Willis to identify the occlusion (e.g., terminal internal carotid artery, M1 or M2 segment of the MCA, basilar artery) and look for any tandem lesions (e.g., a high-grade stenosis in the cervical carotid).
• CT Perfusion (CTP): This final phase provides functional data about brain tissue viability. Using specialized software (like RAPID), it generates maps that estimate the volume of irreversibly damaged brain (infarct core) and the surrounding tissue at risk that is still salvageable (penumbra). The mismatch between the core and penumbra is key for selecting patients for thrombectomy, especially in extended time windows (6-24 hours) based on the DAWN and DEFUSE-3 trials.

3. Radiology Report Template for CT Stroke Protocol (Non-Contrast CT + CTA + CT Perfusion)

Use this template as a starting point for your macros. It’s structured to ensure you hit all the key points the stroke team needs to make a rapid clinical decision.

Technique

Non-contrast CT of the head was performed, followed by CT angiography of the head and neck after the administration of [e.g., 70] mL of intravenous contrast. CT perfusion imaging was also obtained with an additional [e.g., 40] mL of intravenous contrast. Post-processing was performed on a dedicated workstation with automated software analysis.

Findings

NON-CONTRAST CT HEAD:
Parenchyma: No acute intracranial hemorrhage. No evidence of extra-axial fluid collection. Gray-white matter differentiation is [preserved/lost in the following regions: ___]. [If applicable: Hypoattenuation is noted in the ___ consistent with early ischemic change.]
ASPECTS Score: [e.g., 9/10, with 1 point deducted for loss of insular ribbon].
Ventricular System & Cisterns: The ventricles and sulci are [normal for age/prominent]. No hydrocephalus. Basal cisterns are patent.
Other: No acute calvarial fracture.

CT ANGIOGRAPHY HEAD AND NECK:
Intracranial Arteries: [e.g., Occlusion of the distal M1 segment of the left middle cerebral artery.] The remaining vessels of the circle of Willis are patent. No evidence of aneurysm, vascular malformation, or dissection.
Extracranial Arteries: The visualized aortic arch and great vessels are [unremarkable/show atherosclerotic disease]. The bilateral common, internal, and external carotid arteries are [patent/show ___% stenosis]. The vertebral arteries are [patent and symmetric/show ___].

CT PERFUSION:
Automated software analysis (e.g., RAPID) demonstrates:
Infarct Core Volume (CBF <30%): [e.g., 18] mL.
Penumbra Volume (Tmax >6s): [e.g., 95] mL.
Mismatch Volume: [e.g., 77] mL.
Mismatch Ratio: [e.g., 5.3].
The core and penumbra are located in the [e.g., left MCA] territory.

Impression

1. Acute ischemic stroke with findings concerning for a large-vessel occlusion. No evidence of intracranial hemorrhage on the non-contrast CT.
2. Occlusion of the [e.g., distal left M1 MCA segment] on CTA.
3. CT perfusion demonstrates a target mismatch profile, with an estimated infarct core of [e.g., 18] mL and a large salvageable penumbra of [e.g., 77] mL in the left MCA territory. Findings are favorable for mechanical thrombectomy based on DEFUSE-3 criteria.
4. ASPECTS score is [e.g., 9/10].

(Note: Findings were communicated via telephone to Dr. [Name] on the stroke service at [Time].)

4. Free Radiology Template Sources for Residents

Building a personal library of high-quality templates is a rite of passage in residency. While the template above is a great starting point, two great free repositories exist online that are worth bookmarking. They are maintained by major radiological societies and practicing radiologists, offering a wide range of templates across all subspecialties.

• RadReport.org: Curated by the Radiological Society of North America (RSNA), this is one of the most comprehensive and standardized libraries available. You can find peer-reviewed templates for nearly every common study. (https://radreport.org/)
• Radiology Templates (AU): This is an excellent, user-friendly site maintained by Australian radiologists. It offers clean, practical templates that are easy to adapt for your own use. (https://www.radiologytemplates.com.au/home-page/)

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

Templates are essential, but the real bottleneck is often translating your free-form thoughts on positive findings into the rigid structure of the report, especially under time pressure. You see the LVO, you calculate the ASPECTS, you see the perfusion mismatch—but then you have to stop, find your macro, and plug everything into the right fields. This is where AI-powered tools can streamline your workflow.

Instead of dictating into a rigid template, you can dictate your findings naturally: “Stat stroke code, non-con is negative for bleed, looks like a left M1 cutoff on the angio with a hyperdense MCA sign. Perfusion shows a small core around 20 cc and a big penumbra.” GigHz Precision AI is designed to take that free-form dictation and automatically generate a complete, structured report based on pre-loaded templates from the American College of Radiology (ACR) and Society of Interventional Radiology (SIR). It helps ensure all key data points are included in the final impression, making your report clear, concise, and actionable for the clinical team.

6. When Should You Order a CT Stroke Protocol? ACR Appropriateness Criteria

The decision to order a comprehensive CT stroke protocol is guided by the clinical scenario. The American College of Radiology (ACR) provides evidence-based guidelines to help clinicians choose the right test for the right patient. For cerebrovascular disease, the key is the timing and nature of the symptoms.

According to the ACR Appropriateness Criteria for Cerebrovascular Diseases-Stroke and Stroke-Related Conditions, a multimodal CT protocol (NCCT + CTA + CTP) is Usually Appropriate for a patient presenting with a focal neurologic deficit where acute ischemic stroke is suspected, particularly within the first 24 hours. This is the classic indication where identifying an LVO and a treatable penumbra is paramount for guiding thrombectomy.

For a patient with a clinical transient ischemic attack (TIA) whose symptoms have completely resolved, a full stroke protocol may not be the first step. While imaging is still needed, other modalities might be considered. In contrast, for a “wake-up stroke” or a patient with an unknown last-known-well time, the perfusion data from a CT stroke protocol is invaluable for determining if a thrombectomy is still a viable option, extending the treatment window well beyond the traditional 6 hours.

7. How Much Radiation Does a CT Stroke Protocol Deliver?

A common question from clinicians and patients involves radiation dose. A complete CT Stroke Protocol, including all three phases, delivers an estimated effective dose of 5-12 mSv. To put this in perspective, this is comparable to the amount of natural background radiation a person receives over several months to a few years. While it’s more than a single non-contrast head CT, the diagnostic yield in the setting of an acute, potentially devastating stroke overwhelmingly justifies the dose.

Modern CT scanners use numerous dose-reduction techniques, such as automated tube current modulation and iterative reconstruction, to keep the dose as low as reasonably achievable (ALARA) without compromising image quality. The benefit of rapidly and accurately diagnosing a stroke to enable brain-saving therapy far outweighs the small associated radiation risk.

8. CT Stroke Protocol Imaging Protocol — Phases, Contrast, and Reconstructions

A successful CT stroke protocol depends on precise technical execution. The scan is a rapid sequence of three distinct acquisitions, each optimized for a specific diagnostic question. The total contrast volume is typically split between the CTA and CTP phases.

The table below outlines a typical protocol. Note that specific parameters may vary based on the scanner manufacturer and institutional preferences.

Common protocol pitfalls: One of the most critical technical factors is the coverage for the CT perfusion. Older scanners may only cover an 8 cm slab, which can miss infarcts outside the standard basal ganglia region. Modern wide-detector scanners (256- or 320-slice) can provide whole-brain CTP, which is becoming the standard of care. Another potential pitfall is patient motion, which can create significant artifacts on the perfusion maps, sometimes requiring a re-acquisition. Finally, the automated software (e.g., RAPID, Olea, syngo.via) is essential, and familiarity with its outputs and potential artifacts is key to an accurate interpretation.

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. With GigHz Precision AI, you can dictate your positive findings in free form, and the AI will generate a perfectly structured report using ACR and SIR templates. The appropriate Clinical Decision Support (CDS) fires automatically, ensuring your reports are complete and compliant.

All we ask is your feedback so we can keep improving the product for trainees. The signup is simple—no credit card, no long forms. Just reply to the application with three items:

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

Ready to give it a try? Apply for the residents free-access program and we’ll get you set up.

10. Frequently Asked Questions (FAQ)

Is GigHz Precision AI HIPAA-compliant?

Yes. The platform is designed for de-identified workflows by default. It operates on the anonymized text of your dictation and does not require Protected Health Information (PHI) to function. All data is handled within a secure, HIPAA-compliant environment.

Do I need my hospital’s IT department to set this up?

No. GigHz Precision AI is a browser-based tool. There is no software to install on hospital machines. It works on any computer or tablet with a modern web browser, including the call-room PC or your personal iPad.

Does this replace PowerScribe or other dictation systems?

No, it works alongside them. You can dictate as you normally would, then copy-paste your free-form text into the tool to generate the structured report. You then paste the final, clean report back into your PACS/RIS. It’s a supplementary tool designed to improve report quality and structure, not replace your core dictation software.

Can I use this on my phone or iPad?

Yes. The platform is fully responsive and works on mobile and tablet devices, making it easy to use in any clinical setting, whether you’re at your workstation or reviewing a case on the go.

Can I customize the report templates?

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

What happens after my residency or fellowship ends?

We offer continuity plans for graduating residents and fellows who want to continue using the tool in their practice. The goal of the free program is to support you during training, and we make it easy to transition to a standard plan upon graduation if you find it valuable.