The principal con
traindications of the
MRI procedure are mostly related to the presence of metallic
implants in a patient. The
risks of
MRI scans increase with the used
field strength. In general,
implants are becoming increasingly MR safe and an individual evaluation is carried out for each case.
Some patients should not be examined in
MRI machines, or come closer than the
5 Gauss line to the system.
Absolute Contraindications for the MRI scan:
•
elec
tronically, magnetically, and mechanically activated
implants
•
metallic splinters in the eye
Patients with absolute con
traindications should not be examined or only with special
MRI safety precautions. Patients with an implanted
cardiac pacemaker have been scanned on rare occasions, but pacemakers are generally considered an absolute con
traindication. Relative con
traindications may pose a relative hazard, and the type and location of an implant should be assessed prior to the
MRI examination.
Relative Contraindications for the MRI scan:
•
other pacemakers, e.g. for the carotid sinus
Osteosynthesis material is usually anchored so well in the patients that no untoward effect will result. Another effect on metal parts in the patient's body is the heating of these parts through
induction. In addition, image quality may be severely degraded. The presence of other metallic
implants such as surgical
clips etc. should be made known to the
MRI operators. Most of these materials are non-magnetic, but if magnetic, they can pose a hazard.
See also
MRI safety,
Pregnancy,
Claustrophobia and
Tattoos.
•
] and 822 definitions [
]
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