At Parkside MR Center, Patient Safety is Paramount.

Dr. John Phillips, and his levitating stethoscope demonstrating the powerful magnetic field of a MRI scanner (by the way, Dr. Phillips had to remove calipers, watch, pager, credit cards and other metal items prior to this demonstration).

The magnets in MRI scanners are very powerful and pose a safety risk to certain patients. Parkside MR Center has a system in place to insure patient safety. Prior to any MR exam the patient is screened for contraindications and other items that may be hazardous or interfere with a MR examination. The patient fills out a MRI Patient Check List and a Parkside administrator reviews the list personally with each patient.

A broader description of contraindications and hazards follow:

Contraindications: MR Generally Cannot Be Performed (except where noted)

Cardiac Pacemakers – are absolutely contraindicated, however MR compatible pacemakers are being developed. (A few pacemaker patients have been scanned for life threatening situations or inadvertently. These pacemakers must subsequently be meticulously checked for function. Some deaths have been reported.)

Intracranial Aneurysm Clips – are contraindicated, unless the specific type of MR compatible clip can be absolutely documented. Aneurysm clips impanted after 1995 in the U.S.A. are MR compatible.

Neurostimulators/Spinal-Fusion Stimulators – generally are contraindicated. There are two manufacturers that are seeking FDA approval for usage of their product in MR, but under strict guidelines.

Drug Infusion Pumps – generally are contraindicated. There are two models Synchro Med/ Synchro Med EL which are currently FDA approved with specific guidelines.

Metallic Foreign Bodies – may or may not preclude MR scanning depending on type, size and location. These patients must be screened by X-ray, including possible orbital metallic foreign bodies in metal workers/machinists.

Cochlear Implants – contraindicated.

Other Otologic Implants – generally non-ferromagnetic (MR compatible except McGee stapedectomy piston prosthesis which is NOT MR compatible).

Dental Implants – generally are OK, except for those that contain magnetically activated components.

Ocular Implants – some are MR compatible. The types listed below are contraindicated.

		FATIO eyelid spring / wire.
		UNITECH round wire eyelid spring.
		Retinal tach.
		Troutman magnetic ocular implant.

Intravascular Stents, Filters and Coils – any of these are OK after 6-8 weeks following placement, unless they are made of non-ferrous metal eg. titanium in which case they can be imaged right after placement.

Vascular Access Ports and Catheters – OK, except Swan Ganz Catheter.

Penile Implants – OK, except for two types.

Duraphase / Omniphase from Dacomed.

Orthopedic Implants/Prosthesis – OK, MR may cause local heating and MR will cause local image artifact.

Miscellaneous Items Affecting Patient Safety

Heart Valve Prosthesis – OK, but there is a prototype electromagnetically controlled heart valve that is being developed, which is contraindicated.

Pacer Wires (without pacemaker) – controversial area probably OK at low field but questionable at high field imaging.

Holter monitor – contraindicated.

Ventricular-peritoneal Shunts – OK, except SOPHY adjustable pressure valve type.

Swan Ganz Catheter – contraindicated. (Thermal dilutor may melt.)

Dermal Patches – can cause burns during MR study and should be removed.

Pessary, IUD, Diaphragm – OK, but will produce local image artifact.

Hearing Aid – must be removed.

Permanent eyeliner/tattoos – can cause local burns (we suggest low field MR or CT.)

Body rings/spikes – can cause local burns. We suggest they be removed (or use low field MR).

Additional information on Patient Safety

Missile Effect – The magnetic field increases exponentially as the distance to the magnet decreases. We operate our high field magnets at 15,000 gauss (earth’s magnetic field is less than 1 gauss). If a metal object gets close enough to the magnet the metal will be accelerated into the bore of the magnet and becomes a flying missile. A child was recently killed during an MR exam on the East Coast when a respiratory therapist brought an O2 tank into the scan room. It is important to remember that super conducting mid and high field magnets and permanent low field magnets are on all the time – not just during scanning.

MR in Pregnancy – MR imaging of pregnant women is not believed to be hazardous to the fetus, however only a few investigations have examined the possible teratogenic effects of MR. The FDA states current guidelines for MR imaging during pregnancy “have not been established”. According to the Safety Committee of the Society for MRI, MR imaging is indicated if other nonionizing forms of diagnostic imaging are inadequate or if the MR exam provides important clinical information that would otherwise require ionizing radiation eg. X-Ray, CT. Obviously the individual case should be discussed with the clinician, radiologist and patient, and a consent form should be signed by the patient.

Our policy at Parkside has been that MR is generally acceptable after satisfactory radiological consultation in the second and third trimester of pregnancy, but should be excluded unless under life or limb threatening circumstances in the first trimester (this has also been the approach in Great Britain). Gadolinium contrast agents cross the placenta and should not be used in pregnancy especially in the first trimester.

Personnel/Family Members in Scan Room – have essentially the same constraints in the scan room as the patient having the scan.

References:

1. 2001 Syllabus: Special Course – Specialty Categorical Course in Diagnostic Radiology: Practical MR Safety Considerations for Physicians, Physicists and Technologists presented at RSNA Nov 25 – 30, 2001. E. Kanal, M.D., Pittsburgh, PA.

2. Pocket guide to MR procedures and metallic objects: update 2001 / Includes bibliographical references. Shellock, Frank G., PhD. ISBN 0-7817-3353-7

Back to Preparation Index