CTA Abdomen/Pelvis (Mesenteric / Aorta / Iliac) — Dictation, Appropriateness, and Dose for Residents
1. The Stat CTA Aorta Runoff: Your Attending’s Checklist
Stat from the ED. 68-year-old male with tearing back pain radiating to his abdomen, history of hypertension. The ER attending is worried about a dissection. The vascular surgeon is on the phone. Your attending wants to know two things immediately: is there a flap, and are the renals and mesenterics coming off the true lumen? This is not the time to be fumbling with your dictation macro or forgetting the key measurements that determine management. A clean, structured report is the expectation, and getting it right the first time is how you build confidence on call.
When I was a fellow, the pressure on these reads was intense because the findings directly trigger a surgical or endovascular consult. Forgetting to mention the distance from the lowest renal artery to the iliac bifurcation on an AAA study, or failing to describe the true vs. false lumen perfusion of the SMA, meant an inevitable addendum. We’ve built tools and guides to help you nail these complex studies every time; you can find more at the residents and fellows resource hub.
2. What a CTA Abdomen and Pelvis (Aorta and Runoff) Covers and What Attendings Look For
A Computed Tomography Angiography (CTA) of the abdominal aorta and pelvis with runoff is the workhorse for acute and chronic aortic pathology. It’s designed to provide a high-resolution map of the aorta and its major branches down to the feet. While a standard portal-venous phase CT is for general abdominal pain, this is a dedicated arterial study. Your attending expects a systematic evaluation that answers specific clinical questions.
Key questions this study answers:
- Aortic Aneurysm: What is the maximum true perpendicular outer-wall-to-outer-wall diameter? What are the neck characteristics (length, diameter, angulation) for potential endograft (EVAR) planning? Is there thrombus or calcification?
- Aortic Dissection: Is there an intimal flap? Where are the entry and re-entry points? Does the dissection extend into branch vessels (celiac, SMA, renals, iliacs), and are those branches perfused from the true or false lumen? Is there evidence of malperfusion?
- Mesenteric Ischemia: Is there high-grade stenosis or occlusion of the celiac artery, superior mesenteric artery (SMA), or inferior mesenteric artery (IMA)?
- Endoleak Surveillance: After EVAR, is there contrast opacification outside the endograft but within the aneurysm sac? (Requires non-contrast and delayed phases for proper characterization).
- Trauma or Bleeding: Is there active arterial extravasation, pseudoaneurysm, or vessel transection?
3. Radiology Report Template for CTA Abdomen and Pelvis (Aorta and Runoff)
This template provides a solid framework. Modify it based on your institution’s preferences and the specific clinical question. The key is to be systematic, ensuring you comment on every major vessel territory.
Technique
CT angiography of the abdominal aorta and pelvis was performed with runoff to the level of the ankles. Images were acquired following the administration of [##] mL of [Contrast Agent] intravenous contrast. Axial, coronal, and sagittal reformatted images were reviewed. 3D and multiplanar reformatted images were created and reviewed as needed.
Findings
AORTA AND ILIAC ARTERIES:
Aortic size: Normal in caliber at the diaphragm. The maximum infrarenal aortic diameter is [##] cm, measured outer wall to outer wall, perpendicular to the axis of flow. [Describe aneurysm morphology: fusiform vs. saccular, presence of mural thrombus, calcification].
Aortic neck: The distance from the lowest renal artery to the start of the aneurysm is [##] cm. The neck diameter is [##] cm.
Dissection: [Present/Absent]. If present, describe origin, extent, true vs. false lumen, and involvement of branch vessels.
Iliac arteries: The common iliac arteries are [non-aneurysmal/aneurysmal], measuring [##] cm on the right and [##] cm on the left. [Describe stenosis, occlusion, or dissection].
VISCERAL AND RENAL ARTERIES:
Celiac axis: [Patent/Stenosed/Occluded].
Superior mesenteric artery (SMA): [Patent/Stenosed/Occluded].
Renal arteries: [Single/Multiple] renal arteries bilaterally. The main renal arteries are [Patent/Stenosed/Occluded].
Inferior mesenteric artery (IMA): [Patent/Stenosed/Occluded].
LOWER EXTREMITY RUNOFF:
Femoral and popliteal arteries: [Describe patency, stenosis, calcification].
Tibial arteries: Three-vessel runoff to the right ankle. [Describe specific vessel patency: anterior tibial, posterior tibial, peroneal]. Three-vessel runoff to the left ankle. [Describe specific vessel patency].
OTHER FINDINGS:
Kidneys, adrenal glands, spleen, pancreas, liver, and gallbladder are grossly unremarkable. No acute bowel abnormality. No free fluid or free air. Visualized lung bases are clear. Osseous structures are unremarkable for acute fracture.
Impression
- [Size] cm infrarenal abdominal aortic aneurysm. [Add other key descriptors, e.g., “Suitable/Unsuitable neck for endovascular repair,” or “No evidence of rupture.”].
- [No evidence of/Stanford Type B] aortic dissection extending from [origin] to [termination]. The celiac, SMA, and renal arteries arise from the [true/false] lumen.
- [Patent/Occluded/Stenosed] visceral and renal arteries as described above.
- Lower extremity runoff: [e.g., “Patent three-vessel runoff to the ankles bilaterally” or “Severe atherosclerotic disease with occlusion of the left SFA”].
4. Free Radiology Template Sources
Building your own template library is a rite of passage. But you don’t have to start from scratch. Before you reinvent the wheel, check out what’s already been built and vetted by the community. Two great free repositories exist for exactly this purpose.
- RadReport.org: This is the RSNA-curated library. It’s comprehensive, peer-reviewed, and considered a standard reference for structured reporting templates across nearly every modality and subspecialty.
- Radiology Templates (AU): Maintained by Australian radiologists, this site offers a fantastic collection of practical, clean templates that are easy to adapt for your own use.
Bookmark both. They are invaluable resources for finding a high-quality starting point for almost any study you’ll encounter.
5. The Next-Level Move: AI-Assisted Structured Reporting
A good template is your safety net. But the real goal is to dictate your findings naturally and have the report structure itself around them. This is where modern tools can fundamentally change your workflow. Instead of clicking through a rigid template, you can simply dictate the positive findings in free form—”fusiform 5.2 cm infrarenal AAA with a 2 cm neck and severe calcification”—and let an AI assistant build the structured report for you.
Tools like GigHz Precision AI are designed for this. It takes your free-form dictation of findings and maps them into the appropriate sections of a pre-loaded ACR or SIR-compliant template. It also helps surface relevant Clinical Decision Support (CDS) guidance where applicable, ensuring your report contains all the key elements attendings and referring physicians need without you having to manually check boxes. It’s about making your natural workflow faster and more robust.
6. When Should You Order a CTA Abdomen and Pelvis (Aorta and Runoff)? ACR Appropriateness Criteria
The decision to order a CTA is guided by established criteria to ensure the right test is done for the right reason. The American College of Radiology (ACR) provides extensive guidance on this.
For evaluating aortic pathology, CTA of the abdomen and pelvis is a cornerstone. Per the ACR Appropriateness Criteria for Abdominal Aortic Aneurysm: Interventional Planning and Follow-up, CTA is Usually Appropriate for both initial AAA sizing and for pre-procedural planning for endovascular repair (EVAR). It provides the detailed morphological data—neck diameter, length, angulation, and iliac access vessel size—that is critical for device selection.
Similarly, for patients with suspected acute mesenteric ischemia, the ACR criteria on Imaging of Mesenteric Ischemia list CTA of the abdomen and pelvis as Usually Appropriate. It is the fastest and most reliable non-invasive method to identify stenosis, occlusion, or dissection involving the celiac, SMA, or IMA.
When IV contrast is contraindicated due to severe allergy or renal failure, Magnetic Resonance Angiography (MRA) may be an appropriate alternative. For cases requiring immediate intervention, catheter-based angiography remains the gold standard as it allows for both diagnosis and treatment in a single session.
7. How Much Radiation Does a CTA Abdomen and Pelvis (Aorta and Runoff) Deliver?
A CTA of the aorta and runoff is a higher-dose study compared to a routine non-contrast CT. The estimated effective radiation dose is typically in the range of 8 to 20 mSv. The final dose depends on patient size and whether multiple phases (e.g., non-contrast, arterial, delayed) are required.
To put this in perspective, this dose is equivalent to several years of natural background radiation. While the diagnostic benefit in settings like suspected aortic dissection or critical limb ischemia almost always outweighs the risk, it’s a dose we take seriously, especially in younger patients or those requiring frequent surveillance.
| Scan Type | Typical Effective Dose (mSv) | Comparison |
|---|---|---|
| Natural Background Radiation | ~3 mSv per year | Baseline |
| Chest X-ray (PA/LAT) | ~0.1 mSv | ~10 days of background radiation |
| CTA Aorta and Runoff | 8-20 mSv | ~3-7 years of background radiation |
Dose reduction techniques, such as automated tube current modulation and iterative reconstruction algorithms, are standard practice to keep the dose as low as reasonably achievable (ALARA). The source for this data is our internal protocol library, curated by interventional radiologists and cross-referenced with ACR RRL guidelines.
8. CTA Abdomen and Pelvis (Aorta and Runoff) Imaging Protocol — Phases, Contrast, and Reconstructions
The success of a CTA hinges on a well-timed contrast bolus and appropriate reconstructions. The protocol is tailored to the clinical question. A single arterial phase is often sufficient for AAA sizing, but suspected dissection, endoleak, or active bleeding requires a multi-phase approach.
Below is a typical protocol. An 18-gauge IV in the antecubital fossa is essential to achieve the required injection rates.
| Phase | Contrast | Timing | Key Parameters | Purpose |
|---|---|---|---|---|
| Topogram (Scout) | None | N/A | kVp: 120 | Planning scan range |
| Arterial Helical | 100-130 mL @ 4-5 mL/s | Bolus Tracking (ROI on aorta, 150 HU threshold + 5s delay) | kVp: 100, Slice: 0.6-1 mm, Coverage: Diaphragm to mid-thigh | Peak arterial opacification for vessel mapping |
| Delayed (Optional) | From same bolus | 3-5 minutes post-injection | Same as arterial | Detects slow-filling EVAR endoleaks or venous bleeding |
Common protocol pitfalls:
- Incorrect Phasing: Forgetting to add a non-contrast series for a dissection workup (to spot intramural hematoma) or a delayed phase for endoleak surveillance are common misses. Always confirm the indication before starting the scan.
- Inadequate Runoff: If the clinical concern is peripheral artery disease (PAD) or planning for femoral access, ensure the scan coverage extends far enough, typically to the mid-thigh or ankles. Communicate this clearly with the CT technologist.
- Improper Measurement: For aneurysms, always measure outer-wall-to-outer-wall and perpendicular to the center line of flow. An axial measurement in a tortuous aorta will overestimate the true diameter.
9. The 3-Months-Free Offer for Residents and Fellows
3+ months free for radiology residents and fellows
We want to help you look like a rockstar on your reports. Our goal is to let you dictate your positive findings in free form, while our AI generates a perfectly structured report using ACR and SIR templates in the background. The appropriate clinical decision support can fire automatically, ensuring your impressions are complete and actionable.
All we ask in return is your feedback so we can keep improving the product for trainees. To get set up, just provide these three items:
- Your PGY year (e.g., PGY-2, PGY-4)
- Your training type (radiology residency or specific fellowship)
- Your training program / hospital name
There’s no credit card required and no long forms to fill out. Just send us the info above and we’ll get you started. You can apply for the residents free-access program here.
10. Frequently Asked Questions
Is GigHz Precision AI HIPAA-compliant?
Yes. The platform is designed for de-identified workflows by default. No Protected Health Information (PHI) is required to use the tool for generating structured report text from your findings. It operates as a co-pilot for the radiologist, not as part of the permanent medical record or PACS.
Do I need my hospital’s IT department to set this up?
No. It’s a browser-based tool that requires no local software installation. It works on the computer in the reading room, your personal laptop, or even an iPad on call. There is no EMR or PACS integration needed to get started.
How does this work with PowerScribe or other dictation systems?
It works alongside your existing system. Most residents use it on a second monitor or a tablet. You dictate your findings, the AI structures the report, and you can copy-paste the final, clean text directly into your official dictation window. It augments your workflow, it doesn’t replace your dictaphone.
Can I use this on my phone or iPad?
Yes, the platform is fully responsive and designed to work on any modern web browser, including those on tablets and phones. This makes it a great reference and reporting tool to have available when you’re on call and away from your usual workstation.
Can I customize the templates?
Yes. While the system comes pre-loaded with templates based on ACR and other society guidelines, you can create, modify, and save your own templates to match your personal or institutional preferences.
What happens after my residency or fellowship ends?
The free access program is specifically for trainees. After you graduate, you can transition to a standard plan for practicing radiologists. Your customized templates and settings will all be saved and ready for you.
Free GigHz Tools That Pair With This Article
Three free tools that complement the material above:
- ACR Appropriateness Criteria Lookup — Type an indication or clinical scenario in plain language and get the imaging studies the ACR rates for it, with adult and pediatric radiation levels. Built directly from 297 ACR topics, 1,336 clinical variants, and 15,823 procedure ratings.
- GigHz Imaging Protocol Library — A searchable library of 131 imaging protocols with the physics specs surfaced and the matching ACR Appropriateness Criteria alongside. Plain-English narratives readable in 60 seconds, organized by modality.
- GigHz Radiation Dose Calculator — Pick the imaging studies a patient has had and see total dose in millisieverts (mSv) with comparisons to natural background radiation, transatlantic flights, and chest X-rays. Useful for shared decision-making.
Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 7, 2026
