I. Coronary and Peripheral Vascular Stents
The AHA statement clearly states that almost all commercially available coronary stent products have been tested and have been indicated as MR safe. Whereas early peripheral artery stents (before 2007) may be weakly magnetic, all stent products are safe on MRI at ≤3T except for this, and some investigators have confirmed that MR can be performed on the same day of stent implantation. For those peripheral arterial stents that are if magnetic, safety considerations are necessary, but magnetic field exposure after 6 weeks is generally considered to be unproblematic.
Therefore, both bare metal stents and drug-coated stents are MR safe.
II. Mechanical Valves
According to the 2007 AHA statement, almost all commercially available prosthetic heart valves and rings are MR safe and can be MRI’d at ≤3T at any time.
In addition, the “wire” that holds the sternum in place has also been shown to be MR safe, but there may be local thermal effects due to regional variability in materials.
Therefore, mechanical flaps are also safe.
Cardiac suturing and occlusion devices
Most of the suturing and blocking devices are MR safe. Their instructions will indicate whether they have been tested or not.
IV. Inferior vena cava filters
Most IVC filters are MR safe, but for a few magnetic devices, such as Cook’s Gianturco bird nest or Boston Scientific’s Greenfield filter, the guidelines recommend a 6-week interval between MR examinations.
V. Floating catheters
Patients with Swan-Ganz catheters should not undergo MRI. Although in vivo testing has confirmed that MR images can be obtained safely, there are still possible risks associated with catheters, guidewires, etc., and MRI is not recommended.
VI. Temporary pacemakers
Temporary pacing leads retained in the epicardium are MR safe. However, both extracorporeal pacing with adhesive electrodes and transvenous temporary pacing are not recommended for MRI.
VII. Pacemakers and ICDs
The greatest risk of MR examinations with this class of devices lies in the possible displacement of the device, in the change of the procedure, in the influence of the work of the pacemaker itself, or in the thermal effects produced by the electrodes.
However, we are guided by the fact that there are manufacturers who have made a lot of efforts for this purpose, and currently MR-compatible pacemakers have been introduced into the clinic as early as possible. But even so, MRI should be more cautious in this category of patients with MR-compatible pacemakers implanted.
VIII. IABP
Although no systematic safety evaluation has been performed, the 2007 statement clearly states that IABP is an absolute contraindication to MR.
I believe that after reading this article, the next time you encounter a similar problem, you won’t have to go around asking for help.