Cardiovascular implantable electronic devices: a review of the dangers and difficulties in MR scanning and attempts to improve safety
Insights Imaging
Cardiovascular implantable electronic devices: a review of the dangers and difficulties in MR scanning and attempts to improve safety
Pei Ghim Poh 1 3 5 6 7 8
Charlene Liew 1 3 5 6 7 8
Colin Yeo 0 1 3 5 6 7 8
Le Roy Chong 1 3 5 6 7 8
Andrew Tan 1 3 5 6 7 8
Angeline Poh 1 3 5 6 7 8
0 , Singapore 529889 , Singapore
1 Le Roy Chong
2 17-10 Tower 5 , Singapore 150167 , Singapore
3 Charlene Liew
4 Pei Ghim Poh
5 Department of Cardiology, Changi General Hospital , 2 Simei Street
6 Singhealth Radiology Residency , 167 Jalan Bukit Merah
7 Department of Radiology, Changi General Hospital , 2 Simei Street 3 , Singapore 529889 , Singapore
8 Angeline Poh
An increasing number of patients are being treated with cardiovascular implantable electronic devices (CIEDs), many of which are MR conditional. There is a lack of literature on the safe scanning of MR conditional CIEDs. This review article discusses MR imaging safety in patients with implanted CIEDs. Guidelines on safe use and indications of imaging patients with MR conditional CIEDs are described, followed by a pictorial essay of the radiographic features of these devices. We also discuss the challenges of monitoring the patient in the MR environment, advances in MRI conditional imaging of devices, availability, limitations and workflow including vendorspecific and other collaborative efforts to simplify the scanning process. Radiologists must be able to facilitate the safe utilization of MR imaging in patients who have CIEDs. A thorough knowledge of the hazards of imaging non-MR compatible devices is required as well as knowing how to correctly identify and manage the imaging of patients with MR conditional CIEDs. Finally, we propose steps required to facilitate the safe scanning of patients with MR conditional CIEDs adopted in our institution and a contingency plan in the event that an inadvertent MR scan of a patient with a MRI unsafe CIED should occur.
Equipment safety; Equipment design; Magnetic resonance imaging; Pacemaker; Artificial; Physics
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Main Messages
Risks of MR imaging in patients who have CIEDs have been
worked around.
There are many technical limitations in enabling safe MR
scanning of CIEDs.
Radiological identification of MRI-conditional status of
CIEDs is useful.
Standardizing conditions for safe MRI scanning is
important.
We offer example algorithms for facilitating safe MRI
scanning of CIEDs.
Introduction
Magnetic resonance imaging (MRI) has steadily increased in
use worldwide [
1
]. We believe that there is a foreseeable
increase in the number of patients with cardiovascular
implantable electronic devices (CIEDs) who will require a MRI. An
estimated 75% of patients with CIEDs will have an indication
requiring MRI during their lifetime [
2
].
This review article discusses the safe use of MRI in patients
who have implanted CIEDs. Radiologists should have a basic
grasp of the principles behind the re-design and engineering of
these devices, once considered to be an absolute
contraindication to scanning.
The known hazards of MRI unsafe CIEDs are described,
followed by guidelines on safe use, indications and limitations
of imaging patients with MR conditional CIEDs, including a
brief pictorial essay of the radiographic features of these
devices.
Finally, we also offer steps to facilitate the safe
scanning of patients with MR conditional CIEDs in the form
of a proposed guideline, which was adopted in our
institution, and a contingency plan if an inadvertent MR scan
of a patient with a MRI unsafe CIED should occur. These
have been ratified by the authors’ institutional medical
board review process and have been implemented
successfully at the time of writing.
What are MRI safe devices?
Implants, devices or materials should routinely undergo
evaluation prior to a MRI procedure if known, and are categorized
as safe, conditional or unsafe [
3
].
Safe devices are safe within the MR environment. The
object is usually made from non-ferromagnetic components.
There are no MR safe cardiovascular implantable devices at
the time of writing.
Conditional devices are safe for the patient undergoing
MRI only if specific conditions are met. This is usually often
due to the presence of a weakly ferromagnetic component in
the implantable device. Current recommendations support
safe scanning at 1.5 T although several studies with scanning
at 3 T exists.
Unsafe devices pose potential risk(s) to an individual in the
MR environment, for which the physical concepts are
discussed below.
Hazards of imaging MRI unsafe cardiovascular devices
A cardiac pacemaker system is composed of leads and a pulse
generator. Within the pulse generator are connectors, circuitry
and a battery which may be ferromagnetic. This results in
interactions with the magnetic field or RF pulse in MR
environments [
1, 2
].
Magnetic field interactions include torque effect, induced
electrical currents and reed/Hall sensor switch activation. RF
pulse effec (...truncated)