MRI and Implants and Foreign Bodies
If you have to undergo MRI procedure for diagnostic investigation, as you were advised by your physician and you have any foreign body or an implant inside your body, what should you do? The first thing you should do is inform the physician who advised MRI that you have a foreign body or an implant inside your body. Your physician should be aware that you have foreign body or an implant (such as pacemaker, cochlear implant, insulin pump etc.) inside your body and he/she can decide what next to be done for investigation, e.g. your doctor will decide if you must undergo MRI or it can be replaced by other investigation. You also should present the complete information about your implant such as manufacturer of the implant, model, serial number and date of implantation. The same information should be supplied to the radiologist or technologist before entering the room for the MRI scan.
Pacemakers are usually considered as absolute contraindication for MRI (Magnetic Resonance Imaging), as there are several reports of arrhythmia (abnormal rhythms of heart may be fast or tachy-arrhythmia and slower beats or brady- arrhythmia per minute) and even deaths in patients with pacemakers, who have undergone MRI for investigation, although at present there are highly specialized protocols which has been developed that permit MRI scanning of select pacemakers.
There are other implants which all have varying contraindications, depending upon scanner technology, and implant properties, scanning protocols. The other implants which are contraindication for MRI scan includes vagus nerve stimulators, cochlear implants, deep brain stimulators, implantable cardioverter defibrillators etc. All these implants pose a great risk for investigations such as MRI. Scientists and manufacturers are working on the ways to improve designs of such implants so that these implants become less risky.
Presence of magnetic foreign bodies or metal implants such as aneurysm clips, surgical prostheses etc, poses potential risk and there is need to consider the safety precaution on individual basis before doing MRI scan. The metallic implants may pose problems due to radio frequency induced heat to the metal implant or strong magnetic field may cause trauma due to presence of metal implants.
As a safety precaution, many MRI centers have mandatory rule for orbital x-ray on anyone suspected of having metal fragments in their eyes, such as workers of metal works, as they have metal fragments in their eyes frequently.
Scientists and manufacturers have developed implants for long duration use with titanium, as it does not have ferromagnetic property and have poor electric conductivity. The artifacts (appear as regions of empty space around the implant, called “black hole artifactsâ€) also less common with titanium in compare to stainless steel.
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