There are different types of contraindications that would prevent a person from being examined with an MRI scanner. MRI systems use strong magnetic fields that attract any ferromagnetic objects with enormous force. Caused by the potential risk of heating, produced from the radio frequency pulses during the MRI procedure, metallic objects like wires, foreign bodies and other implants needs to be checked for compatibility. High field MRI requires particular safety precautions. In addition, any device or MRI equipment that enters the magnet room has to be MR compatible. MRI examinations are safe and harmless, if these MRI risks are observed and regulations are followed.

Safety concerns in magnetic resonance imaging include:

It is important to remember when working around a superconducting magnet that the magnetic field is always on. Under usual working conditions the field is never turned off. Attention must be paid to keep all ferromagnetic items at an adequate distance from the magnet. Ferromagnetic objects which came accidentally under the influence of these strong magnets can injure or kill individuals in or nearby the magnet, or can seriously damage every hardware, the magnet itself, the cooling system, etc.. See MRI resources Accidents.
The doors leading to a magnet room should be closed at all times except when entering or exiting the room. Every person working in or entering the magnet room or adjacent rooms with a magnetic field has to be instructed about the dangers. This should include the patient, intensive-care staff, and maintenance-, service- and cleaning personnel, etc..
The 5 Gauss limit defines the 'safe' level of static magnetic field exposure. The value of the absorbed dose is fixed by the authorities to avoid heating of the patient's tissue and is defined by the specific absorption rate. Leads or wires that are used in the magnet bore during imaging procedures, should not form large-radius wire loops. Leg-to-leg and leg-to-arm skin contact should be prevented in order to avoid the risk of burning due to the generation of high current loops if the legs or arms are allowed to touch. The patient's skin should not be in contact with the inner bore of the magnet.
The outflow from cryogens like liquid helium is improbable during normal operation and not a real danger for patients.
The safety of MRI contrast agents is tested in drug trials and they have a high compatibility with very few side effects. The variations of the side effects and possible contraindications are similar to X-ray contrast medium, but very rare. In general, an adverse reaction increases with the quantity of the MRI contrast medium and also with the osmolarity of the compound.

See also 5 Gauss Fringe Field, 5 Gauss Line, Cardiac Risks, Cardiac Stent, dB/dt, Legal Requirements, Low Field MRI, Magnetohydrodynamic Effect, MR Compatibility, MR Guided Interventions, Claustrophobia, MRI Risks and Shielding.

Philips Medical System is the diagnostics business of Royal Philips Electronics of the Netherlands, one of the world's biggest electronics companies and Europe's largest. Philips is quoted on the NYSE (symbol: PHG), London, Frankfurt, Amsterdam and other stock exchanges. On October 19, 2001, Philips Medical Systems completed a 3-year acquisition strategy through its purchase of Marconi Medical Systems. Marconi Medical Systems offered leading multislice CT, MRI, and Nuclear Gamma Camera systems to medical institutions around the world. As well as new 3.0T developments, Philips is also in collaboration with researchers at the University of Nottingham, with the intention of developing an ultrahigh field strength clinical 7.0T whole body MR system.

MRI Scanners:

0.23T to 1.0T:
1.5T:
3.0T to 7.0T:
Hybrid Scanners:

Developed by GE Lunar; the ARTOSCANâ„¢-M is designed specifically for in-office musculoskeletal imaging. ARTOSCAN-M's compact, modular design allows placing within a clinical environment, bringing MRI to the patient. Patients remain outside the magnet at all times during the examinations, enabling constant patient-technologist contact. ARTOSCAN-M requires no special RF room, magnetic shielding, special power supply or air conditioning.
The C-SCANâ„¢ (also known as Artoscan C) is developed from the ARTOSCANâ„¢ - M, with a new computer platform.

California-based research and development company. Alliance has several patents regarding 'microbubble' compositions such as Imagent® that are intended to enhance ultrasound imaging and Imagent GI as a gastrointestinal MRI contrast agent. Another product is Oxygent™, a synthetic 'blood substitute'.

MRI Contrast Agents:

• Imagent GI

Aurora Imaging Technology, Inc., a private company, is located in North Andover, Massachusetts. As a leading innovator in the breast imaging industry, the company provides with its Aurora System the detection, diagnosis, biopsy and treatment of breast cancer. Aurora Imaging Technology Inc. develops and manufactures the Aurora® 1.5T Dedicated Breast MR System, the first and only FDA approved MRI system designed specifically for breast imaging.

MRI Scanners: