Written by Dimitrios Vrachatis, Specialist Cardiologist, PhD, National and Kapodistrian University of Athens.
What is cardiac MRI?
Cardiac imaging is a rapidly developing field. Cardiac magnetic resonance imaging uses an MRI scanner to show the heart in three dimensions.
What information does it provide?
It provides highly specialised information about the entire myocardial wall, heart chambers, pericardium and major vessels. Detailed structures can be viewed in still images or moving sequences. It is the reference examination for assessing cardiac function and measuring chamber volumes. It provides:
- Anatomical information
- Functional information
- Information about the composition and quality of myocardial tissue, known as tissue characterisation
When might I need cardiac MRI?
Cardiac MRI is increasingly used as part of a comprehensive assessment of:
- Myocarditis
- Pericarditis
- Cardiomyopathies, including dilated and hypertrophic cardiomyopathy
- Congenital heart disease
- Infiltrative diseases, such as sarcoidosis and amyloidosis
- Heart failure
- Coronary artery disease
- Cardiac tumours
- Intracardiac communications
- Guidance of arrhythmia ablation
It is a specialised examination rather than a routine test. Your cardiologist determines whether it is indicated.
Where is it performed?
In hospitals or diagnostic centres with an MRI scanner and appropriately trained technologists and doctors.
What happens during the examination?
Remove all metal objects from your body and clothing, including watches, coins and keys. An intravenous cannula is inserted for the contrast agent. You then lie on the scanner bed, which moves into its tunnel. Headphones reduce the machine’s noise and allow you to hear instructions, including when to hold your breath. You must remain completely still.
Can it be combined with a stress test?
Yes. Adenosine stress perfusion MRI can assess myocardial ischaemia, similarly to stress echocardiography or myocardial perfusion scintigraphy.
What are the advantages?
High-resolution images help characterise inflammation, fibrosis and necrosis, providing information about myocardial tissue composition. MRI also evaluates cardiac anatomy in three dimensions and provides important functional information without exposing the patient to ionising radiation.
What are the disadvantages?
Despite these advantages and the absence of radiation, MRI is specialised and not always immediately available. It requires a dedicated scanner installation and takes approximately 45–60 minutes, during which the patient must remain still.
Is it painful?
The examination is painless apart from the needle used to insert the cannula for the contrast agent. Remaining still on your back, the scanner noise and feelings of claustrophobia may cause discomfort.
Is preparation needed?
Apart from patients with an MRI-compatible implanted cardiac device, which needs special programming, preparation consists of removing portable metal and electronic objects from the body and clothing. Medication may be given to people at high risk of an allergic reaction to the paramagnetic contrast agent. If you have claustrophobia, discuss this with your doctor beforehand. Open-type scanners can reduce this feeling.
Can I have MRI with an implant, pacemaker or defibrillator?
If you have a pacemaker, defibrillator, CRT device, loop recorder or any other implant, speak to your doctor first. Exact device or implant details are needed. Modern devices and implants may be MRI-compatible, but this must be confirmed.
What happens afterwards?
You can return to your activities immediately after cardiac MRI.
When will the results be available?
Cardiac MRI is complex. Reporting requires specialised digital image processing and detailed interpretation. The report is usually provided a few days after the examination.