MRI & Interactions
Magnetic Resonance Imaging/Angiography, (MRI/MRA), is an innovative diagnostic tool for virtually every clinical speciality. Unlike CT or X-ray angiography, no ionizing radiation or iodine contrast agents are necessary. As a consequence, there has been a great increase in the number of MR procedures.
The MR scanner market is growing rapidly with a tendency towards using higher static magnetic field strengths such as 3 T, 7 T and beyond. MRI is considered as one of the safest non-invasive imaging modalities. However, it is based on strong static magnetic fields and switched gradient magnetic fields in the range of kilo Hertz (kHz) frequencies as well as on radio frequency (RF) (electro-magnetic) fields in the mega Hertz band (MHz).
Besides acceptable and reversable side effects e.g. nausea, vertigo, phosphenes (flashes of light), metallic taste, performing MR scans on humans with implants using instruments or accessories as well as other items can lead to unintended and dangerous interactions, causing safety and diagnostic problems.
Among the products at issue (Devices and Materials in MRI) are:
- vascular implants (e.g. stents, clips, coils, valves),
- orthopedic implants and devices (e.g. hip prostheses, nails, wires, fixation systems),
- active implants (e.g. pacemakers, neurostimulators, infusion pumps, pressure sensors)
- surgical/interventional instruments (e.g. scissors, guidewires, manipulators),
- medical electrical devices (e.g. pulse oximeters, anaesthesia and monitoring equipment, injectors, ventilators, robotic systems)
and all ancillary equipment used within the MR environment.
The patient and device MRI safety can be compromised by magnetically induced displacement forces and torque, RF and gradient-induced heating/voltages/vibration, unintentional output and operational inhibition (device malfunction), etc.. Further on MRI compatibility issues such as materials causing MR image artifacts or decrease the MR image quality can lead to diagnostic errors (inaccuracies/misinterpretations), significant lack of information and difficulties with follow-up exams.
In order to protect the patient and the user as well as the equipment from dangerous MR interactions, intensive MR testing needs to be perfomed according to standardised methods. The aim for today's comprehensive MR testing service is providing a meaningful MR labeling information for devices and items.