CT Adrenal (Multiphase) — Dictation, Appropriateness, and Dose for Residents

1. The Adrenal Incidentaloma — Nailing the Washout Calculation Under Pressure

You’re reading an outpatient CT Abdomen and Pelvis for vague abdominal pain. Everything looks fine, except for a 2.3 cm nodule in the left adrenal gland. You pull up the non-contrast from two years ago — it measured 18 Hounsfield Units (HU). Now the ordering oncologist wants it characterized, and your attending expects a full washout calculation in the report, not just a description. Getting the regions of interest (ROIs) placed perfectly on three separate phases and remembering the exact washout formulas while the list is backing up is a classic resident challenge.

When I was a fellow, I’d see residents either forget to do the calculation or place the ROI in a slightly different spot on each phase, throwing off the numbers. The key is consistency. This guide breaks down the CT Adrenal Mass Protocol, gives you a rock-solid template, and shows you how to nail the report every time. For more guides like this, check out the residents free-reference hub, which has other templates and clinical calculators.

2. What a CT Adrenal Mass Protocol (Washout) Covers and What Attendings Look For

The entire purpose of a CT adrenal washout study is to differentiate a benign, lipid-poor adrenal adenoma from something more concerning, like a metastasis, pheochromocytoma, or adrenocortical carcinoma. The principle is simple: benign adenomas tend to take up contrast and then “wash it out” quickly, while malignant lesions and pheochromocytomas tend to retain contrast on delayed imaging.

Your attending is looking for a few key data points, presented clearly:

• Precise Measurements: The size of the mass in three dimensions.
• Hounsfield Unit (HU) Values: The mean attenuation of the mass on non-contrast, portal venous, and 15-minute delayed phases.
• The Washout Calculation: The calculated Absolute Percentage Washout (APW) or Relative Percentage Washout (RPW).
• A Definitive Conclusion: A clear statement characterizing the mass based on the imaging features and washout characteristics (e.g., “features consistent with a lipid-poor adenoma”).

Remember, if the non-contrast attenuation is 10 HU or less, the diagnosis is a lipid-rich adenoma, and the study is essentially done. No need for contrast or washout calculations. The real work begins when that non-contrast value is over 10 HU.

3. Radiology Report Template for CT Adrenal Mass Protocol (Washout)

Use this template as a starting point for your macros. The key is to be systematic. Before dictating the impression, double-check your ROI placement — make sure you’re on the same axial slice in all three phases, avoiding any cystic or necrotic areas.

Technique

Non-contrast, portal venous phase, and 15-minute delayed phase CT images were acquired through the adrenal glands. [100] mL of [Omnipaque 350] intravenous contrast was administered. 3D reconstructions were performed as needed.

Findings

COMPARISON: [Date of prior study]

ADRENAL GLANDS:

Right adrenal gland: Unremarkable.

Left adrenal gland: There is a [size] cm mass.

Attenuation measurements are as follows:

Non-contrast: [##] HU

Portal venous phase (60 seconds): [##] HU

Delayed phase (15 minutes): [##] HU

Absolute percentage washout: [##]%

Relative percentage washout: [##]%

[Describe other features: morphology, calcifications, heterogeneity, surrounding fat stranding.]

REMAINING ABDOMINAL AND PELVIC ORGANS:

[Briefly comment on the liver, spleen, pancreas, kidneys, bowel, and any other relevant findings.]

LUNGS: Visualized lung bases are clear.

BONES: No acute fracture or destructive osseous lesion.

Impression

Key Principles for Your Impression:

• Non-contrast HU ≤10: This is a lipid-rich adenoma. Diagnosis made.
• Absolute Percentage Washout (APW) >60%: Consistent with a lipid-poor adenoma. Use APW = (PV HU − Delayed HU) / (PV HU − Non-contrast HU) × 100.
• Relative Percentage Washout (RPW) >40%: Consistent with a lipid-poor adenoma. Use RPW = (PV HU − Delayed HU) / PV HU × 100. (Only use if no non-contrast phase is available).
• Washout <60% APW or <40% RPW: Indeterminate. Consider metastasis, pheochromocytoma, or adrenocortical carcinoma. Recommend biochemical correlation and potentially further imaging like MRI or PET-CT.
• Large, Ugly Masses: A mass >4-6 cm with central necrosis, irregular margins, or invasion suggests adrenocortical carcinoma and needs surgical evaluation, regardless of washout numbers.

Example Impression:

1. A [2.3] cm left adrenal mass with an absolute percentage washout of [75%], consistent with a lipid-poor adenoma.

2. No other acute abdominopelvic process.

4. Free Radiology Template Sources

Building your own macro library is a rite of passage, but you don’t have to start from scratch. If you’re looking for templates beyond this one, two great free repositories exist. The RSNA-curated RadReport.org has a comprehensive library covering most subspecialties. For a slightly different flavor, check out the Australian-maintained Radiology Templates site, which also offers a wide range of free, peer-reviewed templates.

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

Templates are a great starting point, but the real friction comes from plugging in the positive findings. You see the mass, you measure the Hounsfield units, and you dictate it. Then you have to stop, tab through the template fields, and make sure everything lines up. This context-switching slows you down and breaks your diagnostic flow.

This is where AI-driven tools can streamline your workflow. Instead of dictating *into* a template, you dictate your positive findings in free form. An AI assistant then parses your language and automatically generates a complete, structured report using pre-loaded ACR and SIR-compliant templates. For example, GigHz Precision AI is designed to do exactly this, helping you create clean, attending-ready reports without the manual formatting. It supports the complex logic needed for frameworks like LI-RADS, Bosniak, and adrenal washout, ensuring the right data ends up in the right place.

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

The decision to order a dedicated adrenal protocol usually follows the discovery of an “incidentaloma” on a scan done for another reason. The American College of Radiology (ACR) provides guidance on this exact scenario.

Per the ACR Appropriateness Criteria for an “Incidentally Discovered Adrenal Mass,” a dedicated multiphase CT with washout is Usually Appropriate for characterizing an indeterminate adrenal mass (one that is >10 HU on non-contrast imaging). This is the classic indication. The goal is to confirm or rule out a benign adenoma non-invasively.

However, CT isn’t the only option. The ACR also notes key alternatives:

• MRI of the abdomen with chemical shift imaging is also rated as Usually Appropriate. It’s an excellent radiation-free alternative, particularly sensitive for detecting intracellular lipid in adenomas.
• FDG PET-CT is also Usually Appropriate, especially in a patient with a known malignancy where the primary question is adrenal metastasis. Benign adenomas are typically not FDG-avid, while most metastases are.

Ultimately, the choice between CT washout and MRI often comes down to institutional preference, patient factors (like renal function or MRI contraindications), and the specific clinical question.

7. How Much Radiation Does a CT Adrenal Mass Protocol Deliver?

A three-phase adrenal washout protocol is a moderate-dose study. Because it requires non-contrast, portal venous, and delayed scans through the same anatomy, the dose adds up. The estimated effective dose is typically in the range of 10-18 mSv.

To put that in perspective, this dose is roughly equivalent to several years of natural background radiation. It’s important to justify this exposure, which is why the protocol is reserved for characterizing indeterminate masses, not for initial screening. When possible, if a recent non-contrast CT is available, it should be used as the non-contrast phase to avoid a repeat scan and reduce the overall dose.

Always confirm your institution’s specific protocols, as many have implemented dose-reduction techniques like automated tube current modulation to keep radiation exposure as low as reasonably achievable (ALARA).

8. CT Adrenal Mass Protocol — Phases, Contrast, and Parameters

A successful adrenal washout study depends on precise technical execution. The timing of the contrast bolus and the delayed phase are critical for accurate calculation. The protocol is designed to capture peak enhancement in the portal venous phase and then measure the degree of contrast washout after 15 minutes.

Below is a typical set of parameters for this protocol. Note that the coverage is focused specifically on the adrenal glands (roughly T11 to L2) to minimize radiation dose, rather than scanning the entire abdomen on all three phases.

Common protocol pitfalls: The most common pitfall is incorrect timing for the delayed phase. The 15-minute delay is standard and has the highest specificity for adenoma. While some literature supports a 10-minute delay, it is slightly less specific. Rushing the delayed scan can lead to an inaccurate washout calculation and an indeterminate result.

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

3+ months free for radiology residents and fellows

If you want to look like a rockstar on your reports, we’re offering an extended free trial of 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, with the appropriate clinical decision support firing automatically. It helps you move faster without sacrificing quality.

All we ask in return is your feedback so we can keep improving the product for trainees. Signup is simple — no credit card, no long forms. To get started, just provide these three items:

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

Ready to give it a try? Visit the application page and reply with those three details to get set up: apply for the residents free-access program.

10. Frequently Asked Questions

Is it HIPAA-compliant?

Yes. The platform is designed for de-identified workflows by default. No patient-identifying information is required or stored, ensuring compliance with HIPAA privacy and security standards.

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

No. GigHz Precision AI is browser-based and requires no local software installation. It works on any modern computer, including the call-room PC or your personal iPad, without needing IT approval or setup.

Does this replace PowerScribe or other dictation systems?

No, it works alongside them. Most residents dictate their findings into the tool, let the AI generate the structured report, and then copy-paste the final, clean text into their institutional PACS/RIS or PowerScribe system. It’s a workflow enhancement, not a replacement.

Can I use this on my phone or iPad?

Yes, the platform is fully responsive and works on mobile devices and tablets. This is particularly useful for reviewing cases or drafting reports away from a dedicated workstation.

Can I customize the templates?

Yes. While the system comes pre-loaded with standard ACR and society-based templates, you can create, modify, and save your own templates to match your personal style or your institution’s specific requirements.

What happens after my residency or fellowship ends?

We offer continuity plans for graduating trainees who want to continue using the platform in their practice. Special pricing is available for those transitioning from training to attending roles.