Cardiac MRI – Cardiac Magnetic Resonance Imaging
A Cardiac MRI is a specialised scan, creating detailed moving images of the heart.
Heart symptoms often occur when you are active e.g. walking, climbing stairs, or exercise. The aim of this test is to see how well blood supplies the heart muscle when your heart is coping with extra exercise or ‘stress’.
The MRI scanner works using the combination of a powerful magnetic field forces and computing power. It doesn’t involve the use of radiation such as X-rays.
Preparing for my scan
Prior to arranging the MRI scan, because the scanner is a ‘magnet’, you will need to let us know if you have:
24 hours before your MRI - do not to drink or eat anything that contains caffeine.
- a pacemaker / defibrillator.
- ever had any metal fragments in your eyes.
- any implants or surgical clips in your body or head.
- ever had an operation on your head, eyes, ears, heart or chest.
- any concerns that you are pregnant.
- had an operation in the last 6 weeks.
- a cochlear implant.
- any kidney issues.
Caffeine is a stimulant and may invalidate the rests of the tests. Caffeine is found primarily in tea, coffee, fizzy drinks and chocolate. There are also traces of caffeine in decaffeinated teas, green teas and coffees, so these must also be avoided. All chocolate products have caffeine, including ice cream and hot drinks. It is best to drink only water and fruit juices for these 24 hours. If you are in any doubt as to whether something contains caffeine, please do not consume it. Otherwise, you may eat normally.
During my scan
On arrival, you will change into a hospital gown and complete a safety questionnaire. The MRI scan will be explained, and any questions will be answered.
A plastic cannula (needle) will be insert into a vein in your arm, which will be used to give you the MRI contrast agent dye (a colourless liquid) and, in some cases, a heart stimulating medication during the scan. An ECG may also be carried out.
Once ready to proceed, you will then go into the scanner room and lie down on the MRI scanner table. During the examination, you heart will be monitored by ECG; your blood pressure, heart rate and oxygen levels will also be measured.
During the scan, the table will be moved into the centre of the MRI. You will hear a rhythmic tapping sound which may become quite loud. This is normal and you will be given headphones to protect your ears from the noise.
The radiographer operating the scanner can see and speak to you at all times. You will be able to hear them over the speaker and they will let you know when you to hold your breath. A breath hold will be for up to about 20 seconds. You will be given a call button to alert the staff if you need to speak to them at any time to let them know how you are feeling or if you have a problem.
After my scan
Once the scan is complete, the cannula will be removed. You should have no aftereffects from this examination. You may eat and drink normally and you can return to regular activities.
Your MRI scan pictures will be interpreted by a specialist and the results will be sent to the doctor who referred you.
Are there any risks?
No short-term harmful effects have been found from Magnetic Resonance Imaging (MRI) scans. The use of magnetic fields is not thought to be harmful; however, long term side effects are unknown.
If you have a cardiac pacemaker, metal fragments in your eyes or brain aneurysmal clips you may not be able to have a MRI because of the magnetic fields in use.
The heart stimulating drug used during the scan can occasionally cause electrical or rhythm problems and/or chest pain or tightness. You might also feel flushed, have a headache, or become short of breath, as you would if you were exercising. These effects usually last only a short time and our staff are fully trained to look after you if you feel these effects.
You will feel a pin prick when the needle is inserted into your vein and will likely have a warm, flushed sensation during the injection of the contrast material. There is a small risk of bruising around the injection site in the arm.
There is a very small risk of allergy or side effects from the injection of the MRI contrast agent, but this is extremely rare. These are usually mild and may include a metallic taste, itchy skin, pain at the injection site and feeling lightheaded. Headache and chest pain are rare.
If you do experience any side effects, please inform the Magnetic Resonance Imaging (MRI) staff immediately.
A Cardiac MRI usually takes between 45 and 60 minutes. With preparation and changing afterwards you can expect to be in department from 1.5 to 2 hours.