I’m not a doctor, but I’ve worked with cardiologists, interventionists, and radiologists. With 15 years experience in ultrasound imaging, and being in clinical and cath-lab settings – my beliefs led me to the conclusion that when evaluating for heart function and CAD, nuclear exams like cardiac PET and MRI Calcium score (Ca+) exam do not provide the most straight forward answers a patient may want.

In the realm of cardiac imaging, echocardiograms (echo), cardiac PET scans, Heart MRI, and cardiac CT scans each offer unique insights into heart health. While each modality has its own strengths, the choice between them often depends on the specific clinical question at hand. Here, I will explore the benefits and limitations of each, highlighting why a cardiac CT might be preferable to a cardiac PET scan and why an echo is superior for functional assessment.

 

Echocardiograms utilize ultrasound technology to provide detailed images of the heart’s structure and function. This non-invasive test is invaluable for assessing the heart’s pumping ability and valve function. A significant advantage of echocardiography is its ability to offer real-time functional information without the need for radiation exposure or contrast agents. Stress echocardiograms, which simulate exercise conditions, further enhance its utility by revealing how the heart performs under stress. Your heart may be fine at rest, but increase it’s demand on a treadmill, and statistically speaking I can, find underlying blockage 85% of the time.

An echo evaluates cardiac function, making it an excellent choice for diagnosing and monitoring conditions like heart failure, LVH (often from high BP), valve disorders (like aortic stenosis, and mitral valve prolapse), and cardiomyopathies (including Covid myocarditis, pericarditis). It is also widely utilized in a screening, and can replace a stethoscope when a cardiologist only offers Telehealth. Its accessibility and safety profile make it a preferred first-line test in many clinical scenarios.

Cardiac PET scans are imaging tests that use radioactive tracers to assess myocardial perfusion and metabolic activity. While they provide detailed insights into blood flow and can detect abnormalities at the microvascular level, PET scans involve radiation exposure and are more invasive due to the need for tracer injection. Better technology and improved this modality, though I haven’t worked around or with clinicians with the latest nuclear equipment, I still doubt it’s overall value. They are useful in complex cases where precise perfusion assessment is critical, such as in diagnosing cardiac sarcoidosis or evaluating myocardial viability post-infarction.

However if I was a patient that had an MI recently, an angiogram and possible stent is what I would want right away. If it’s an old MI, I still would rather have an Echo/Stress Echo for heart function. Lastly, the four hour exam, complexity and cost of PET scans, along with the exposure to radiation, limit their routine use. Though used for specific diseases, It seems to me a Cardiac CT, or echo could provide better information, quicker.

MRI calcium scores are ordered to assess the amount of calcified plaque in the coronary arteries, which can be an indicator of atherosclerotic disease. However, it is important to understand that a high calcium score does not directly indicate coronary artery disease (CAD) because calcium itself is not plaque but a marker of calcified arteries or calcified plaque. The presence of calcium suggests that there has been a process of plaque formation and stabilization over time, but it does not provide information about non-calcified, potentially unstable plaques that are more likely to lead to acute coronary events. I’ve seen cases with people having a Ca+ score of 1000 (extremely high), though having zero CAD. I’ve also seen cases with a calcium score of 0 with significant CAD. While calcium scoring can improve risk stratification, particularly in intermediate-risk patients, it does not replace the need for other diagnostic tools that assess the functional impact of coronary artery disease, such as echocardiograms or stress tests. In many cases, cardiac CT angiography (CTA) is preferred over cardiac PET scans for anatomical assessment because it provides detailed images of both calcified and non-calcified plaques without the need for radioactive tracers. However still, the dye injected into the coronaries are toxic to the kidneys. For those of you with CAD or suspected CAD – request an echo for function, and a CT for coronary artery disease.

Echocardiograms (and Stress Echocardiograms done by an experienced Sonographer) remain superior for evaluating heart function, offering real-time insights into cardiac performance without radiation exposure, making them a valuable tool for assessing the functional implications of CAD.

 

Cardiac CT scans, particularly CT angiography (CTA), offer exceptional anatomical detail, making them ideal for evaluating coronary artery disease. They provide clear images of coronary anatomy, allowing for the assessment of stenosis and plaque characteristics. Unlike PET scans, CT scans do not require radioactive tracers, reducing the patient’s radiation exposure. CT scans are also faster and less invasive, making them more patient-friendly.

In many cases, cardiac CT can replace PET scans, especially when detailed anatomical information is needed without the functional insights that PET provides. For instance, CT is excellent for ruling out coronary artery disease in low to intermediate-risk patients, providing a comprehensive view of the coronary arteries.

While cardiac PET scans offer functional and metabolic insights, their use is often limited to specific clinical scenarios due to their complexity and radiation exposure. Cardiac CT scans, on the other hand, provide superior anatomical detail with less invasiveness, making them a more practical choice in many cases. Angiograms are now becoming only utilized for interventions (stents), rather than evaluating for CAD. MRI Ca+ scoring will tell you if your artery is calcified, but not if there is any blockage. Echocardiograms remain the gold standard for functional assessment, offering real-time insights into cardiac performance without the risks associated with radiation. Ultimately, the choice of imaging modality should be guided by the specific clinical question and patient needs, with echoes and CT scans often being the preferred options for functional and anatomical assessment, respectively.