What is an MRI scan?
Magnetic resonance imaging (MRI) is a type of scan that uses magnetic waves to produce very detailed images of the body. It is a painless and safe procedure and helps to diagnose illnesses. This helps doctors to treat disease earlier and more effectively. It is an unparalleled test for many brain and spinal diseases, joint problems, and to make cancer diagnoses.
Why is it sometimes hard to get an MRI if you have a pacemaker?
In the past, MRI scans for patients with pacemakers (pacemakers or ICD) was not done. Unlike stents and valves which are safe, pacemakers contain electronics and batteries that can be affected by a strong magnet, like an MRI machine. Doctors were worried the exposure would break the device.
Every year in the world, there are 1 million new pacemakers implanted, and 60 million MRI scans performed. It is really common that someone with a pacemaker would need an MRI scan – if it were possible.
What we now know is that it is much safer than we thought – we were too careful. In many hospitals, it is now routine to scan pacemakers as long as we follow careful rules. These rules are now published, but not all hospitals do this yet.
Even though MRI is fairly safe it still requires following strict protocols, and coordination between the heart and MRI teams. This makes MRI scans logistically harder to organise. It important to always tell your doctor that you have a cardiac device. This is because the device needs to be programmed before and after the MRI and carefully monitored during the scan.
Why may MRI be important for you?
More than half of people in their lifetime with a pacemaker will get an illness where MRI would help. Other tests can be done, but for many diseases, MRI gives the best information. The brain, spine, breast, liver, prostate, heart and all other organs can be scanned.
How can I find out if I can have an MRI with my pacemaker?
At the time of implant, your team should tell you if you can have an MRI scan, based on your pacemaker specification. If you can, your device is “MRI conditional”. Some pacemakers are easy to scan – they have been built for MRI. These are called “MRI conditional” devices. Strict rules still need to be followed, but people with this type of pacemaker should have the least problems getting a scan – although we usually wait 6 weeks after the pacemaker is put in.
If you are unsure, you can find out if your device is “MRI conditional” from the following places:
- Check your pacemaker registration card. The latest guidelines advise doctors to mention this on the card.
- If you are unsure, you can call your device manufacturer directly.
- Ask the department that routinely checks your device.
How to make a decision about having an MRI scan?
Newer pacemakers have been thoroughly tested in an MRI scanner and we know they are safe. Still, we need to follow strict protocols to do this. Most hospitals should be able to scan perform your scan but experience and awareness – even amongst doctors – is still growing.
Older pacemakers (or “legacy devices”) were not approved to undergo MRI. Sometimes there are also remaining bits of old pacemakers still in the heart (old leads). We used to call these “unsafe”. However, if we are careful, and the scan is important for care, and the alternatives are less good, then we can usually scan these. This is because the benefit outweighs any risk. This may require discussion between your doctor, cardiologist and radiologist. It may be done in an MRI department that does lots of them.
Regardless of the type of device, an MRI scan is only safe if the device is carefully programmed and there is the correct monitoring for the duration of the scan. It is always important to tell the department about the device beforehand as otherwise the scan may be cancelled. You may need to help provide details to the department.
What are the risks?
MRI is an extremely safe imaging modality. 15,16 There are theoretical risks with scanning a person with a pacemaker. The include heating around the pacemaker leads, or changes to how the pacemaker functions. And so newer devices were developed that meant the risk is minimal when appropriate protocols are followed. These devices are termed “MRI-conditional” devices, as the scan needs to follow certain conditions.
Older devices which have not been tested in an MRI environment can still be scanned. What we now know is that it is much safer than we thought – we were too careful. Recent large studies suggest that when protocols were followed, there was no serious risk. Out of 3000 scans, one patient- where protocol was not followed- did need their battery changed. Considering that these scans can be necessary to treat important diseases (cancer, strokes, and radiotherapy for example), the benefit usually far outweighs this risk but adequate patient monitoring and safety procedures are needed.