HIDA Scan (Cholescintigraphy) — Dictation, Appropriateness, and Dose for Residents

1. The HIDA Scan Read: From “Equivocal” to Definitive

The ED is on the line. 45-year-old female, right upper quadrant pain, fever, and leukocytosis. The overnight ultrasound was “equivocal for cholecystitis”—some wall thickening, no stones, a negative sonographic Murphy’s sign. Now they’ve ordered a HIDA scan, and your attending wants a definitive answer, stat. You need to know the exact sequence: when should the gallbladder fill? Do you need morphine? What’s the ejection fraction cutoff? Getting the report right means knowing the protocol cold.

When I was a junior resident on nucs call, I spent half the time looking up the NPO rules and the correct morphine dose. Having a solid template and reference makes all the difference between a confident read and a fumbled report. For more tools like this, check out the residents and fellows resource hub.

2. What a NM HIDA Scan (Cholescintigraphy) Covers and What Attendings Look For

A HIDA scan, or cholescintigraphy, isn’t about anatomy—it’s a functional study of the hepatobiliary system. We use a Tc-99m labeled radiotracer to watch the bile production and excretion pathway in real-time. Ultrasound is the first-line test for cholecystitis, but when it’s ambiguous, HIDA is the problem-solver.

This study provides a clear, functional answer to several key clinical questions:

• Acute Cholecystitis: Is the cystic duct obstructed? This is the core question.
• Chronic Acalculous Cholecystitis / Biliary Dyskinesia: Is the gallbladder contracting properly in response to stimulation?
• Bile Leak: Is there radiotracer activity outside the biliary system, for instance, after a cholecystectomy?
• Biliary Obstruction: Is the common bile duct patent?
• Neonatal Biliary Atresia: Can the infant excrete bile into the small bowel?

Your attending is looking for a report that methodically addresses the normal sequence of events: hepatic uptake, biliary duct visualization, gallbladder filling, and tracer passage into the small bowel. Any deviation from this sequence is a key finding.

3. Radiology Report Template for NM HIDA Scan (Cholescintigraphy)

This template provides a solid foundation for your dictation. Modify the bracketed text based on your specific findings. Remember the key principles: non-visualization of the gallbladder is the hallmark of acute cholecystitis, and an ejection fraction below 38% suggests biliary dyskinesia.

Technique

Radiopharmaceutical: [5.0] mCi of Technetium-99m mebrofenin was administered intravenously.

Imaging Protocol: Dynamic anterior images of the abdomen were obtained for 60 minutes. [If applicable: Delayed imaging was performed up to [4] hours.] [If applicable: At 60 minutes, [0.04] mg/kg of morphine sulfate was administered intravenously, and imaging continued for an additional 30 minutes.] [If applicable: Following initial visualization of the gallbladder, [0.02] µg/kg of sincalide (CCK) was infused over [60] minutes to calculate the gallbladder ejection fraction.]

Findings

There is prompt hepatic uptake of the radiotracer by 5 minutes. The common bile duct is visualized by [10] minutes. The gallbladder [is/is not] visualized by 60 minutes.

[If gallbladder is NOT visualized by 60 minutes]: Following morphine administration, the gallbladder remains non-visualized at 90 minutes total scan time.

[If gallbladder IS visualized]: The gallbladder is visualized at [45] minutes. Radiotracer activity is seen within the small bowel by [50] minutes, confirming patency of the common bile duct.

[If GBEF was performed]: The calculated gallbladder ejection fraction is [25]%. The sincalide infusion [did/did not] reproduce the patient’s clinical symptoms.

[If looking for a bile leak]: There is [no] evidence of radiotracer activity outside the expected course of the biliary tree to suggest a bile leak. [OR: There is an abnormal collection of radiotracer in the [right subhepatic space], consistent with a bile leak.]

Impression

[For Acute Cholecystitis]:
Non-visualization of the gallbladder, even after morphine augmentation. Findings are highly specific for acute cholecystitis due to cystic duct obstruction.

[For Chronic Cholecystitis]:
Delayed visualization of the gallbladder at [e.g., 75 minutes, after morphine]. This finding is most consistent with chronic cholecystitis.

[For Biliary Dyskinesia]:
1. Patent biliary system with normal visualization of the gallbladder and passage of tracer into the small bowel.
2. Low gallbladder ejection fraction of [25]% (normal >38%), consistent with biliary dyskinesia.

[For Normal Study]:
Normal hepatobiliary scan. No evidence of acute cholecystitis or biliary obstruction.

4. Free Radiology Template Sources

Building a personal library of templates is a key part of residency. Beyond your own macros, two great free repositories exist that are worth bookmarking. The Radiological Society of North America (RSNA) curates a comprehensive library at RadReport.org, covering nearly every modality. For a slightly different perspective, an excellent Australian-maintained library is available at RadiologyTemplates.com.au.

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

Templates are great, but the real goal is a fluid, efficient workflow. Instead of clicking through structured reporting fields or constantly editing a static macro, you can dictate your positive findings in free form and let an AI handle the rest. GigHz Precision AI is designed for this. You dictate the key findings—”gallbladder fails to visualize at 60 minutes, even after morphine”—and the tool generates a clean, structured report based on pre-loaded ACR and SIR templates. It helps streamline the reporting process, ensuring your reports are consistent and complete without slowing you down.

6. When Should You Order a NM HIDA Scan? ACR Appropriateness Criteria

The American College of Radiology (ACR) provides evidence-based guidelines to help clinicians choose the right test. For the common indication of Right Upper Quadrant Pain, the guidance is clear. Ultrasound is the undisputed first-line imaging modality for evaluating the gallbladder and biliary tree.

However, when ultrasound results are equivocal or non-diagnostic in a patient with a high clinical suspicion for acute cholecystitis, cholescintigraphy (HIDA scan) is rated as Usually Appropriate. It serves as the definitive functional problem-solver in this scenario. Other alternatives include MRCP, which is excellent for evaluating ductal anatomy and choledocholithiasis, and ERCP, which is both diagnostic and therapeutic but more invasive.

7. How Much Radiation Does a NM HIDA Scan Deliver?

Patients often ask about radiation, and it’s our job to provide a clear answer. A typical HIDA scan delivers an effective radiation dose of 3-5 mSv. This places it in a low-to-moderate exposure tier, comparable to several months to a few years of natural background radiation that we all receive just by living on Earth. The dose is well within accepted diagnostic limits and is justified when the clinical question cannot be answered by non-ionizing imaging like ultrasound.

8. NM HIDA Scan (Cholescintigraphy) Imaging Protocol

A successful HIDA scan depends heavily on correct patient preparation and a standardized imaging protocol. The goal is to track the flow of Tc-99m mebrofenin from the liver into the gallbladder and small bowel. Key variables include the patient’s NPO status, potential morphine augmentation to increase specificity, and sincalide (CCK) stimulation for functional assessment.

A common pitfall is misinterpreting a non-visualized gallbladder in a patient with chronic cholecystitis. Using morphine augmentation is critical here; it increases sphincter of Oddi tone, raising biliary pressure. If the cystic duct is patent (as in chronic disease), the gallbladder will eventually fill. If it remains unseen, it’s strong evidence for acute obstruction.

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 generates a structured report using ACR + SIR templates with the appropriate clinical decision support firing automatically. 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 apply, just provide these three items:

1. Your PGY year (e.g., PGY-2, PGY-4)
2. Your training type (radiology residency or specific fellowship — IR, body, MSK, neuro, peds, breast, nucs)
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

Is GigHz Precision AI HIPAA-compliant?

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

Does this require a complex IT setup at my hospital?

No. GigHz Precision AI is browser-based and requires no local software installation or special permissions from your IT department. It works on any modern computer, including the call-room PC or your personal laptop or iPad.

How does it work with PowerScribe or other dictation systems?

It works alongside your existing system. You can dictate into the GigHz web interface, and once the structured report is generated, you can copy and paste it directly into your PACS/RIS. It complements your existing workflow rather than replacing it.

Can I customize the templates?

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

What happens after I finish my 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 continue using the tool as you start your career.