MRI Safety and Patient Management
Zones and access control
Know the four ACR zones (I unrestricted, II transition, III restricted, IV magnet room) and who may enter each. Zone IV access requires MR personnel screening. Understand the difference between the static fringe field (5-gauss line) and the controlled access boundary.
Implants and devices
Candidates must distinguish MR-safe, MR-conditional, and MR-unsafe labeling and know that MR-conditional devices specify field strength, SAR, and coil-type limits that must be verified before scanning. Cardiac pacemakers/ICDs, cochlear implants, and some aneurysm clips are classic hazards. Projectile risk from ferromagnetic objects is the leading cause of injury; the magnet is always on.
Biological effects and contrast
Static field (sensory/vertigo), gradient fields (peripheral nerve stimulation, acoustic noise), and RF (heating, SAR, burns from conductive loops). Gadolinium: know nephrogenic systemic fibrosis risk in renal impairment and the distinction between linear and macrocyclic agents.
Patient management
Screening forms, metal detection, hearing protection, thermal insulation, IV access, and monitoring of sedated or pediatric patients. Quench procedures and cryogen asphyxiation/oxygen-displacement risk.
Traps
Questions often imply the field can be "turned off" for entry - it cannot without a quench. MR-conditional is not the same as MR-safe. A device safe at 1.5 T is not automatically safe at 3 T.
Rule of thumb
If a device's labeling does not explicitly permit the field strength and conditions in use, do not scan it.