MRI Safety Flashcards
6 cards from real MRI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 MRI Safety flashcards as text
Which MRI zone is defined as the area containing the MRI scanner itself where the static magnetic field is always present?
Answer: Zone IV
Zone IV is the MRI scanner room where the magnet is always on and unrestricted ferromagnetic items pose immediate danger.
A patient reports having a cardiac pacemaker. What is the standard MRI safety classification for most older pacemakers?
Answer: MR Unsafe
Most older pacemakers are classified MR Unsafe because the magnetic field can interfere with device function or cause heating.
What is the main biological risk associated with rapidly switching gradient magnetic fields during an MRI scan?
Answer: Peripheral nerve stimulation
Rapidly switching gradients can induce electrical currents in body tissue, causing peripheral nerve stimulation (PNS).
Which SAR limit (Specific Absorption Rate) is the FDA guideline for whole-body RF energy deposition in a 15-minute period for non-controlled conditions?
Answer: 4 W/kg
The FDA guideline for whole-body average SAR under normal operating mode is 4 W/kg over any 15-minute period.
A patient with a metallic foreign body in the eye should be evaluated with which imaging modality BEFORE entering the MRI suite?
Answer: CT scan
A CT scan of the orbits is used to detect metallic ocular foreign bodies before MRI because ferromagnetic metal near the eye is a contraindication.
What term describes an object becoming a high-speed projectile when brought near a strong MRI magnetic field?
Answer: Missile effect
The missile effect (or projectile effect) occurs when ferromagnetic objects are rapidly accelerated toward the bore by the strong static magnetic field.