Myocardial Perfusion (SPECT or PET) — Dictation, Appropriateness, and Dose for Residents

1. The Nuc Med Read You Can’t Punt

It’s 3 PM. The cardiologist is on the phone asking about the outpatient Myocardial Perfusion Imaging (MPI) you just read. They don’t want a wishy-washy report. They want to know: Is there reversible ischemia? What’s the ischemic burden? Is the Left Ventricular Ejection Fraction (LVEF) preserved? Your attending expects a clean, structured report that matches the defect to a coronary territory and gives a clear bottom line. This isn’t just about finding a “defect”; it’s about quantifying risk and guiding the next step in management, whether that’s medical therapy or a trip to the cath lab. When I was a fellow, I learned that a confident nuc med read makes you a hero to the cardiology team. A vague one just creates more work for everyone. For more high-yield guides like this, check out our free residents and fellows resource hub.

2. What a Nuclear Medicine Myocardial Perfusion Imaging (SPECT) Study Covers and What Attendings Look For

Myocardial Perfusion Imaging (MPI), often performed with Single-Photon Emission Computed Tomography (SPECT), is the workhorse for functional assessment of coronary artery disease (CAD). It directly visualizes myocardial blood flow at rest and under stress, allowing you to differentiate between ischemia and infarct. It’s most valuable for patients with an intermediate pretest probability of CAD, for pre-op risk assessment, or for evaluating the functional significance of a known stenosis.

Your attending is looking for a report that systematically answers these key clinical questions:

• Is there reversible ischemia? This is the money finding—a perfusion defect seen on stress images that is not present on rest images. It implies a flow-limiting stenosis.
• Is there a fixed defect? A defect present on both stress and rest images suggests prior myocardial infarction or scar.
• What is the ischemic burden? Quantify the extent (small, medium, large) and severity (mild, moderate, severe) of any reversible defects. This is a major prognostic indicator.
• What is the Left Ventricular (LV) function? Gated SPECT provides the LVEF, regional wall motion, and wall thickening. A fixed defect with akinesis and no wall thickening confirms scar.
• Are there secondary signs of severe CAD? Look for Transient Ischemic Dilation (TID), where the LV cavity appears larger on stress images than on rest images. This is a high-risk finding suggestive of severe, often multivessel, disease.

3. Radiology Report Template for Nuclear Medicine Myocardial Perfusion Imaging (MPI / SPECT)

This template provides a solid foundation. Remember to tailor the findings to the specific patient. The key is to be systematic, comparing stress to rest for every segment.

Technique

PROCEDURE: Rest/stress myocardial perfusion imaging was performed using a [1-day/2-day] protocol.

RADIOPHARMACEUTICAL: [Technetium-99m sestamibi/Technetium-99m tetrofosmin].

STRESS PROTOCOL: The patient underwent [exercise treadmill/pharmacologic] stress. For exercise stress, the patient achieved [X] METs and [Y]% of the maximum predicted heart rate. For pharmacologic stress, [0.4 mg of regadenoson was administered as an IV bolus / adenosine was infused at 140 mcg/kg/min].

IMAGING: Gated SPECT images of the myocardium were acquired following both rest and stress radiotracer injections. Attenuation correction was performed using [low-dose CT/line source].

Findings

COMPARISON: [Comparison to prior study from YYYY-MM-DD].

PERFUSION:
Overall perfusion: [Normal/Abnormal].
Stress images demonstrate a [small/medium/large], [mild/moderate/severe] perfusion defect in the [anterior wall, septum, apex, lateral wall, inferior wall].
Rest images demonstrate [complete reversibility/partial reversibility/no significant change] in this defect.
[ADDITIONAL FINDINGS: e.g., There is an additional fixed perfusion defect in the [territory].]

LV FUNCTION (GATED ANALYSIS):
Left ventricular ejection fraction (LVEF): [X]%.
Regional wall motion: [Normal/Specify abnormality, e.g., Hypokinesis of the inferior wall].
Wall thickening: [Normal/Specify abnormality, e.g., Reduced thickening in the inferior wall corresponding to the perfusion defect].
Left ventricular volumes: End-diastolic volume [X] mL, End-systolic volume [Y] mL.
Transient Ischemic Dilation (TID) ratio: [X] (Normal < 1.2). [TID is/is not present].

Impression

1. [NORMAL MYOCARDIAL PERFUSION STUDY / ABNORMAL MYOCARDIAL PERFUSION STUDY].

2. [IF ABNORMAL:] Evidence of a [small/medium/large], [mild/moderate/severe] area of [reversible ischemia] in the [anterior/septal/apical/lateral/inferior] wall, consistent with ischemia in the territory of the [LAD/LCx/RCA] coronary artery. This represents a [low/intermediate/high] risk finding.

3. [IF FIXED DEFECT:] Evidence of a [small/medium/large] fixed perfusion defect in the [territory], consistent with prior myocardial infarction.

4. Left ventricular ejection fraction is [preserved/mildly reduced/moderately reduced/severely reduced] at [X]%. [No] evidence of transient ischemic dilation.

4. Free Radiology Template Sources

Building your own template library is a rite of passage. But you don’t have to start from scratch. Two great free repositories exist that can give you a head start on almost any study you’ll encounter on call. They are excellent for finding a solid starting point that you can then customize for your own dictation style and your institution’s preferences.

• RadReport.org: The RSNA-curated template library. It’s comprehensive, peer-reviewed, and considered a standard by many. (https://radreport.org/)
• Radiology Templates (AU): A fantastic, well-organized library maintained by Australian radiologists with a very practical, clinically-oriented focus. (https://www.radiologytemplates.com.au/home-page/)

5. The Next-Level Move: Free-Form Dictation with AI-Powered Structuring

The best template is the one you don’t have to think about. Instead of clicking through a structured report or trying to remember every field in your macro, you can just dictate the positive findings as you see them. For example: “Large, severe, completely reversible defect in the apex, anterior wall, and septum. The EF is down at 35% with associated wall motion abnormalities.” The challenge is turning that efficient, free-form dictation into the perfectly structured report your attending and the referring clinicians expect.

This is where tools like GigHz Precision AI come in. It’s designed to take your natural language dictation of the key findings and automatically generate a complete, structured report based on pre-loaded ACR and society-backed templates. It helps ensure that details like ischemic burden, LVEF, and TID are consistently documented in the right places, making your reports clearer and more clinically useful without slowing you down.

6. When Should You Order a Nuclear Medicine Myocardial Perfusion Imaging Study? ACR Appropriateness Criteria

Deciding on the right cardiac imaging test is a common clinical question. The American College of Radiology (ACR) provides evidence-based guidelines to help. For a patient presenting with chest pain where there is suspicion for acute coronary syndrome, the choice of imaging depends heavily on their pretest probability of having coronary artery disease.

According to the ACR Appropriateness Criteria for Chest Pain-Suspected Acute Coronary Syndrome, MPI is Usually Appropriate for patients with an intermediate pretest probability of CAD. For low-risk patients, a stress ECG alone is often sufficient. For high-risk patients or those with an acute MI, coronary angiography is the definitive test.

When considering MPI, it’s also important to know the alternatives. Stress echocardiography is a great option that avoids radiation. Coronary CT Angiography (CCTA) provides excellent anatomic detail of the coronary arteries but doesn’t assess the functional significance of a stenosis. Cardiac MRI stress perfusion offers high resolution without radiation but may have limited availability. Finally, PET MPI can provide higher resolution images at a lower radiation dose than SPECT if it’s available at your institution.

7. How Much Radiation Does a Myocardial Perfusion Imaging Study Deliver?

Patients often ask about radiation, and it’s our job to have a clear answer. The effective radiation dose from an MPI study depends on the protocol and radiotracer used. Modern protocols are designed to minimize dose while maintaining diagnostic quality.

A standard 1-day Technetium-99m (Tc-99m) sestamibi or tetrofosmin protocol delivers an effective dose of approximately 6-10 mSv. This is comparable to a few years of natural background radiation. Some centers may still use Thallium-201 (Tl-201), particularly for viability assessment, which results in a higher dose.

Here’s a quick comparison to put that in perspective:

Dose reduction is always a priority. Using weight-based dosing, state-of-the-art gamma cameras, and advanced reconstruction software all contribute to keeping the dose as low as reasonably achievable (ALARA).

8. Myocardial Perfusion Imaging Protocol — Phases, Radiotracer, and Stress Options

A typical Tc-99m MPI protocol involves two distinct phases: stress and rest. The goal is to acquire two sets of images of the heart—one showing blood flow at peak stress and another showing blood flow at rest—to identify any flow disparities that would indicate ischemia. The order (rest-stress vs. stress-rest) and timing (1-day vs. 2-day) can vary by institution.

The table below outlines the key parameters for a common 1-day stress-first protocol.

Common protocol pitfalls: The biggest pitfall is patient prep. Caffeine consumed within 12-24 hours can block the effects of vasodilator stress agents like regadenoson and adenosine, potentially causing a false-negative study. For exercise stress, beta-blockers or calcium channel blockers can blunt the heart rate response, preventing the patient from reaching their target. A 1-day protocol is faster for the patient but can have some “shine-through” from the first injection affecting the second; a 2-day protocol is cleaner but less convenient.

9. The Residents & Fellows Offer: 3+ Months Free Access

Look like a rockstar on your reports. We’re offering 3+ months of free access to GigHz Precision AI for all radiology residents and fellows. You can dictate your positive findings in free form, and the AI will generate a complete, structured report using the appropriate ACR or SIR templates. Clinical Decision Support (CDS) for frameworks like LI-RADS, BI-RADS, and Bosniak fires automatically when needed.

All we ask in return is your feedback so we can keep improving the product for trainees. The 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? 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. It operates on the de-identified text of your report, not on raw DICOM images or protected health information (PHI). It’s built to integrate securely into the clinical environment.

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 workstations in the reading room or your personal laptop or iPad at home. There’s nothing for IT to install or whitelist.

Does it work with PowerScribe or other dictation systems?

Yes. It works alongside any dictation system. You dictate as you normally would. You can then copy-paste your free-form findings into the tool, and it generates the structured report, which you can then paste back into your PACS/RIS. It’s a workflow enhancement, not a replacement for your core dictation software.

Can I use it on my phone or iPad?

Yes. The platform is fully responsive and works well on tablets like the iPad, which is perfect for reviewing a report or checking a template when you’re away from a full workstation.

Can I customize the templates?

Yes. While the platform comes pre-loaded with standard ACR and society-backed templates, you can customize them to match your personal preferences or your institution’s specific formatting requirements. Your customizations are saved to your personal profile.

What happens after I finish residency or fellowship?

We have straightforward, physician-friendly pricing for attending radiologists. Your customized templates and profile come with you. The goal is to provide a tool that grows with you from training into your professional practice.