Cardiac MRI

Cardiac MRI: Procedure, Purpose, and What to Expect

Diagnosing heart conditions often requires highly detailed imaging to understand how well the organ is functioning. As a complex organ with intricate structures and constant motion, even minor abnormalities can significantly impact overall health. Cardiac MRI, or heart MRI scan, is one of the most advanced imaging tools available today to study the heart’s structure and function. It helps doctors visualise the anatomy of the heart, assess how effectively it pumps blood, and detect issues that other imaging methods might not reveal.

In this blog, we will explore what a cardiac MRI is, why and when it’s recommended, how it works, and what to expect before, during, and after the procedure. 

What is a Cardiac MRI?

A cardiac MRI is a non-invasive imaging technique that makes use of powerful magnetic fields, radio waves, and computer technology to create detailed images of the heart, including its chambers, valves, and muscles. It is considered one of the safest imaging techniques and is ideal for long-term monitoring since it does not involve exposure to radiation.

As a comprehensive method for evaluating the heart, a cardiac MRI provides the following information:

  • Size and thickness of the heart chambers
  • The condition of the heart muscle
  • How well the heart is pumping
  • The blood flow through major vessels
  • The presence of tissue-damage or scarring

It is particularly valuable in detecting heart diseases that affect the muscle tissue or blood supply, such as myocarditis, cardiomyopathy, or coronary artery disease.

Why Is a Cardiac MRI Needed?

A cardiac MRI is often preferred for the precise information it provides about the heart over other imaging tests. While echocardiograms and CT scans are often the first steps, MRI offers superior soft-tissue contrast, enabling specialists to see not just how the heart looks but also how it works.

Here are some of the reasons why a cardiac MRI is often preferred:

  • Evaluating heart muscle disorders
  • Assessing tissue damage after a heart attack
  • Diagnosing inflammation or infection
  • Monitoring congenital heart disease
  • Evaluating blood flow and heart function
  • Planning and guiding treatment

In short, a cardiac MRI provides a comprehensive picture of the heart’s anatomy, its performance, and tissue health. 

When Is a Cardiac MRI Recommended?

A cardiac MRI is recommended when specific heart conditions require detailed imaging or when other diagnostic tests leave questions unanswered. Cardiologists often recommend this test to confirm or further evaluate findings from echocardiograms, CT scans, or angiograms.

It’s commonly recommended for people with or suspected of having:
Coronary artery disease or prior heart attack: MRI helps identify areas of reduced blood flow and permanent muscle damage.

  • Heart failure: It measures ejection fraction (how well the heart pumps blood) and identifies the underlying cause, such as dilated or hypertrophic cardiomyopathy.
  • Congenital heart disease: MRI maps structural defects and evaluates post-surgical repairs.
  • Heart inflammation: In suspected myocarditis or pericarditis, MRI visualises tissue inflammation, swelling, or scarring.
  • Valvular heart disease: It assesses valve anatomy, blood flow, and pressure differences.
  • Cardiac tumours or masses: MRI distinguishes between benign and malignant growths.
  • Arrhythmias related to structural heart problems: It helps detect scarring or fibrosis that may trigger irregular rhythms.

How Does a Cardiac MRI Work?

A cardiac MRI works by using powerful magnets, radio waves, and computer technology to create highly detailed images of the heart, all without using X-rays or radiation. It works on the principle of magnetic resonance, a property of hydrogen atoms naturally present in the body. 

When you lie inside the MRI scanner, the machine generates a strong magnetic field that causes the hydrogen atoms in your body to align in one direction. Short bursts of radiofrequency waves are then sent through the area being examined. These pulses temporarily disrupt the alignment of the atoms. When the radiofrequency signal stops, the atoms return to their normal state and release energy. The scanner detects these energy signals, and a computer processes them into highly detailed, cross-sectional images of the heart and surrounding vessels. 

Because the heart is constantly moving, the scanner uses a special technique called cardiac gating to synchronise image capture with your heartbeat and breathing. This ensures that the images are sharp, accurate, and free from motion blur.

In some cases, a contrast dye is injected into a vein before or during the scan. The contrast helps highlight specific tissues, blood flow patterns, or scarred areas within the heart muscle, thereby providing doctors with even clearer diagnostic information. 

Essentially, cardiac MRI combines physics, precision imaging, and computer processing to visualise how the heart looks and functions in real time. This makes it one of the most advanced and reliable tools for assessing heart structure, blood flow, and tissue health in a single, noninvasive test.

What Happens During a Cardiac MRI?

As we have already discussed, cardiac MRI is a painless, non-invasive procedure and is usually completed within 30 to 60 minutes. 

The procedure begins with the medical team reviewing your medical history, checking for any metal implants or pacemakers, and asking you to remove all jewellery and metallic items. You will be asked to change into a hospital gown before lying on a flat table that slides into the MRI scanner, which is a large, cylindrical machine. 

Small electrodes will be placed on your chest to monitor your heartbeat throughout the scan. This allows the system to capture images at specific points in your cardiac cycle. In some cases, an intravenous (IV) line will be inserted in your arm to deliver a gadolinium contrast agent, which improves image clarity.

During the scan, you’ll hear tapping or thumping sounds as the machine operates. Earplugs or headphones are provided for comfort, and you can communicate with the technologist via an intercom. You’ll be asked to lie still and occasionally hold your breath for a few seconds while images are taken. This helps prevent blurring.

Mild sedation might be given if you are anxious or claustrophobic. The entire experience is safe, carefully monitored, and designed to capture precise heart images with minimal discomfort.

What Are the Risks of a Cardiac MRI?

Cardiac MRI is considered one of the safest imaging techniques with minimal or no risk. It doesn’t involve radiation exposure, making it suitable even for people who require repeated imaging over time.

That said, there are a few considerations to keep in mind. Here are some of the potential concerns and precautions associated with the procedure:

  • Magnetic interference with metal implants: The powerful magnetic field can affect certain implants, such as older pacemakers, defibrillators, or surgical clips. Therefore, it is important to inform your doctor about any metal in your body before your scan. 
  • Pregnancy considerations: MRI is generally safe during pregnancy, but it’s usually avoided in the first trimester unless absolutely necessary. Gadolinium contrast is only used when the benefits clearly outweigh the risks.
  • Reactions from dye: Although rare, some people may experience mild side effects from the contrast dye, such as an allergic reaction, altered taste, dizziness, headache, or nausea.

How Should I Prepare for a Cardiac MRI?

Here are some of the steps you need to take before having a cardiac MRI done:

  • Wear comfortable clothes without zippers or metal parts, and remove all jewellery, watches, or accessories before the scan.
  • You can usually eat and drink normally, though some centres may ask you to avoid caffeine or heavy meals a few hours before the test.
  • Take your regular medicines unless advised otherwise, but inform your doctor if you use heart or blood pressure medications.
  • Tell your healthcare team if you’re pregnant, have kidney problems, or have had allergic reactions to contrast dye before.
  • If you’re uncomfortable in tight spaces, let your medical team know in advance so they can make arrangements to help you relax and stay comfortable throughout the procedure.

What Happens After a Cardiac MRI?

After the scan, there’s no special recovery period for most people. You can go back to your usual activities right away. If a contrast agent was used, it will gradually leave your body through the kidneys.

The MRI images are reviewed by a radiologist or cardiac imaging specialist, who will interpret the results and share them with your cardiologist. Based on the findings, your doctor may discuss next steps, which could include medication adjustments, further tests, or treatment plans.

In some cases, cardiac MRI results are used to:

  • Confirm or rule out a diagnosis
  • Monitor how well a treatment or surgery has worked
  • Plan interventions such as bypass surgery, stenting, or device placement

Why Choose Magnus Diagnostics for Advanced Cardiac MRI in Thrissur?

When it comes to heart health, accuracy and trust are non-negotiable. With the right diagnostic partner, you can be assured of precise results, timely reports, and expert guidance to make confident medical decisions. 

At Magnus Diagnostics, we combine advanced cardiac imaging technology with expert interpretation to deliver results that truly make a difference. Our focus is on ensuring every patient receives an accurate, comfortable, and reassuring diagnostic experience.

With a comprehensive range of diagnostic services, including MRI, CT, ultrasound, digital X-ray, and laboratory testing, Magnus Diagnostics offers complete diagnostic support for every patient. This integrated approach ensures convenience, continuity of care, and consistent results, making it easier for both patients and doctors to make informed decisions with confidence.