- Part 1 by Dr Marco Gotte discussing the basics of MRI
- Part 2 by Professor Richard Sutton discussing special aspects of MRI in patients with Devices and those who may receive them
Lecturer: Doctor Marco Gotte
The aims of this first lecture are:
- create awareness for a (novel) growing clinical problem: Clinicans are confronted with an increasing number of patients with a device, and an increasing clinical need for a MRI scan
- explain the (technical reasons of) interaction between MRI and devices (and vice versa)
- point out the effects/hazards of MRI scanning on pacemaker functioning
- provide a strategy to overcome the MRI and device interaction and to minimize risk of scanning in (conventional) pacemaker patients
- to pay attention to labelling of devices
Lecturer: Professor Richard Sutton
My talk will be about special aspects of MRI in patients with Devices and those who may receive them:
- Presence of redundant leads in the body is a very strong contraindication for MRI
- How to persuade Clinical Radiologists that a scan is possible with reasonable precautions in patients who have received a MRI compatible device
- The same process is also necessary for Clinical Neurologists as they are the most frequent requesters of MRI scans and many currently do not appreciate the technical progress recently made in Devices
- Cost of Devices and impact on the budget of the implanting centre
- If all patients cannot receive a MRI compatible Device who should receive?
- Parts of the body that can be scanned with each approved Device and even if the isocentre of the scan is remote from the scan target what can be learnt by the CMR specialist or Radiologist
- What Devices without MRI compatibility can be scanned? What precautions are necessary? ECG and Oximetry monitoring in all.
Richard Sutton answers your questions:
Subject: Old leads
New MRI safe devices and old leads. How should this be handled?
R.S: Old leads are a problem. A MRI conditional device will help but the indications for MRI must be strong and the precautions taken also very strong. Abandoned leads are an absolute contraindication for MRI.
Subject: Monitoring of the patient during the mri scan
You have told that the mri scan can disturb the ECG monitoring. During an MRI scan, don't we need to monitorate the electrical activity of the patient to synchronise images?
R.S: ECG Monitoring is possible. The equipment is not cheap and the tracings available are imperfect but for CMR an ECG is obligatory. The imperfections are such that pulse oximetry is required in addition.
Subject: MRI in pt with PPM
would you recommend a pt with a non MRI PPM to have a MRI scan done?
RS: Yes but the indications for MRI must be strong and preferably the patient should not be pacemaker dependent and the device and lead manufactured after 2000. If these criteria are not met the risk is higher for patient and pacing system.
Subject: MRI in PPM pt
what is the risk of having a MRI before 6 weeks after a ppm implant? What the risk of a patient with Biotronik PPM to have a full body MRI?
1. Six weeks are chosen to allow the leads to gain full stability in the heart by endotheliailisation. There is at least a theoretical danger of lead displacement by torque in those first 6 weeks.
2. The risks of a full body scan in a device that is not approved for one are several. A: There will be an arrhythmia or asystole. B. There will be a great threshold rise on lead or leads requiring reprogramming or reoperation. C. There will be damage to the generator and D. If there are problems and you are sued, you are not covered at all against the legal risks
Subject: PM patients
In patient with PM, swiched of the PM,,, MRI is totaly safe?
R.S: No, the system is still subject to all the problems of MRI except that the device will not trigger an arrhythmia.
Subject: non-MRI CEIDS
Can we still do MRI in patients who do not have MRI safe CEIDS
R.S: Yes, but a strong indication for MRI is required, plus preferably the device and leads should have been manufactured after 2000 and the patient not be pacemaker dependent. Strong precautions as discussed in the session are required.
Subject: Perspective on IEDs
What in your opinion is more cost effective? Removing and replacing existing devices with types that are safe with MRIs or simply investing more in research on how to better and more safely conduct MR scan with the already implanted devices?
R.S: MRI is MRI and no amount of research will ameliorate the risks of MRI to CIED patients. The solution lies in the design of the devices and leads plus very careful precautions. MRI will develop in the future to pose new problems e.g., 3 and 7 Tesla machines which will pose new design problems on CIED systems. This is where the money needs to be spent.
Subject: Device failure frequency
Is the safety problem of MRI in patients with cardiovascular implantable electronic device just hypothetical? Is there any large study showing a high frequency of device failure?
R.S: It is not a hypothetical problem. Deaths of CIED patients in MRI have been recorded but for an up to date review of this I suggest to read Beinart R, Nazarian S. Magnetic resonance imaging in patients with implanted devices. J Cardiovasc Electrophysiol 2012; 23: 1040-1042.
Subject: Insertable Cardiac Monitors
Why Patients with a Reveal ICM implanted in sites other than the subcutaneous region of the chest are contraindicated for an MRI procedure?
R.S: They are not contraindicated in any situation. ILRs, however, are implanted typically nearer the heart than other CIEDs. They make a large artefact and may adversely influence the interpretation of CMR as shown in my presentation.
Subject: old leads
New MRI conditional devices and old leads. Safe with precautions?
R.S: This combination requires the same precautions as if no part of the system is MRI conditional. May I suggest that it is better to avoid the term ‘safe’ as nothing in this field is safe. Whatever we do has risks and these have to be carefully weighed and the best decision made for each patient.
Patients with renal failure often need an MRI because of contraindication to CT with iodinated contrast. Are these patients on the priorities list of the implantation of the
new MRI-designed implantable cardiac devices?
R.S: This is a valuable point and it is reasonable to give them priority
The safety of MRI scanning of pacemakers and ICDs: what are the critical elements of safe scanning? Ask me again at 10 000. Europace 2010; 12:, 915–917
Wilkoff BL, Bello D, Taborsky M, Vymazal J, Kanal E, Heuer H, et al: EnRhythm MRI SureScan Pacing System Study Investigators. Magnetic resonance imaging in patients with a pacemaker system designed for the magnetic resonance environment. Heart Rhythm 2011; 8: 65-73.
Nazarian S, Hansford R, Roguin A, Goldsher D, Zviman MM, Lardo AC, Caffo BS, Frick KD, Kraut MA, Kamel IR, Calkins H, Berger RD, Bluemke DA, Halperin HR. A prospective evaluation of a protocol for magnetic resonance imaging of patients with implanted cardiac devices. Ann Intern Med. 2011;155: 415-424.