If your cardiologist has ordered a cardiac MRI , it's normal to have questions: What is it for? Do I need to prepare? Is contrast used? How long does the test take?
Cardiac MRI is one of the most comprehensive imaging tests for studying the heart and obtaining highly accurate information about its structure and function. Below, we explain in simple terms how a cardiac MRI is performed, what information it provides, and what you can expect on the day of the test.
What is a cardiac MRI and what is it used for?
Cardiac magnetic resonance imaging (MRI) is a diagnostic test that uses a magnetic field and radio waves to obtain detailed images of the heart. Unlike other imaging techniques, it does not use ionizing radiation.
Thanks to these images we can study aspects such as the size and anatomy of the heart, the movement of its walls, its contraction capacity and the presence of certain alterations in the cardiac muscle.
One of its main advantages is that it allows for highly accurate characterization of heart tissue and the detection of, among other alterations, the presence of scars, fibrosis, edema, or inflammation.
Cardiac MRI can provide information that complements other tests, such as echocardiography, and is especially useful when we need to delve deeper into the diagnosis.
When is a cardiac MRI requested?
The cardiologist may order this test in various situations. Its most common applications include:
- Studying diseases of the heart muscle or cardiomyopathies.
- Detect and assess a possible myocarditis or inflammation of the heart.
- Analyze the damage produced in the heart muscle after a myocardial infarction.
- Studying certain diseases of the heart valves.
- Evaluate the size, anatomy, and function of the heart chambers.
- To supplement the information obtained through other cardiological tests when necessary to reach a diagnosis more precise.
The indication will always depend on the clinical situation of each patient and the information that the specialist needs to obtain.
Is cardiac magnetic resonance imaging safe?
Yes. Cardiac magnetic resonance imaging is a safe test for the vast majority of patients and has the advantage of not using X-rays or ionizing radiation.
One of the main precautions is related to the presence of pacemakers, defibrillators, or other metallic devices or implants.
If you have any of these conditions, you must inform the medical team beforehand. Many current devices allow MRI scans under certain conditions, but it is necessary to check their compatibility beforehand and follow the corresponding protocol.
How is a cardiac MRI performed?
On the day of the test, you will have to lie face up on a stretcher that moves into the magnetic resonance imaging equipment.
Before starting, electrodes will be placed on your chest to monitor and synchronize the images with your heartbeat . It is also common to use headphones or earplugs to reduce discomfort from the noise generated by the equipment during image acquisition.
During the scan, you will be asked several times to hold your breath for a few seconds . Don't worry: this is a normal part of the procedure and allows for clearer images by reducing chest movement.
It is important to remain as still as possible during the scan and follow the instructions provided by the team.
Is contrast used in cardiac MRI?
In many studies it is necessary to administer a gadolinium-based contrast agent through an intravenous line, usually in the arm.
This contrast allows for obtaining additional information about the heart muscle and can help identify certain alterations, such as areas of fibrosis, scarring, or inflammation.
It is a different contrast agent than that usually used in computed tomography (CT) tests, and allergic reactions are rare.
Before administering it, the healthcare team will assess whether there are any circumstances that require special precautions.
How long does a cardiac MRI take?
One of the most frequent questions is how long a cardiac MRI lasts.
Although it will depend on the type of study that needs to be performed, a complete cardiac magnetic resonance imaging scan usually lasts approximately between 45 and 60 minutes.
During that time you must remain lying down and as still as possible to ensure the quality of the images.
How should I prepare for a cardiac MRI?
Generally speaking, the preparation is simple. However, you should always follow the specific instructions provided by the center where you will take the test.
As general recommendations:
- It is not usually necessary to come fasting.unless otherwise instructed by the medical team.
- You can take your usual medication, unless you receive specific instructions.
- Before entering the room you must remove the metal objectssuch as watches, jewelry, belts, hair clips, or other accessories.
- Please inform us in advance if you have claustrophobiaThe team will be able to assess the available options to facilitate the test.
- Please report if you carry a pacemaker, defibrillator, prosthesis, surgical clips or other implanted device.
- Inform the team if is she pregnant or is there a possibility of pregnancy.
If you have any questions about your medication, medical history, or the presence of any implants, it is best to consult with them before the examination.
Does a cardiac MRI hurt?
No. Cardiac MRI is a painless test.
The main discomforts may be due to having to remain still for a prolonged period, holding your breath for a few seconds at different times, or the noise generated by the equipment.
If contrast is needed, you will only feel the usual discomfort of having an intravenous line inserted.
What if I have claustrophobia?
Some people may feel uncomfortable inside the MRI machine. If you know you are claustrophobic or have had difficulties undergoing an MRI in the past , it is important to let us know in advance.
The healthcare team will be able to explain how the test is performed and assess the measures available to help you carry it out with greater peace of mind.
When will I get the results?
Once the test is completed, the specialist will carefully analyze the numerous images obtained and prepare the corresponding report.
Your cardiologist will be able to explain the results to you at your follow-up appointment and assess their significance along with the other tests and your medical history.
If any findings are identified that require urgent assessment, the medical team will contact you without you having to wait for your next scheduled appointment.
Cardiac magnetic resonance imaging: a very comprehensive test to study the heart
Cardiac magnetic resonance imaging is a very valuable, safe diagnostic tool without ionizing radiation , which allows the heart to be studied with a high level of detail.
Your cardiologist ordering this test shouldn't be cause for alarm. Often, we simply need more precise information to confirm or rule out a diagnosis , better understand the state of your heart, and decide on the most appropriate course of action.
As with any cardiac test, if you have any questions before, during or after the examination, consult with the medical team.
At the Comprehensive Cardiology Unit, we are here to guide and support you throughout the entire process.
By Dr. Teresa Alvarado Houses
Head of the Advanced Imaging Unit