MRI safety Flashcards
Static magnetic fields
Missile effect, projectiles, patient implants
Gradient magnetic field
Potential for mild peripheral nerve stimulation/discomfort and skeletal muscle contraction
RF electromagnetic fields
Heating effects
Static magnetic field is always
Turned on and objects can turn into projectiles
What info do gradient magnetic fields provide
Positional info to scan, lowest to isocentre
Changing magnetic fields can induce
Electrical currents in conducting medium which causes heat
Gradient magnetic fields have potential for
Mild peripheral nerve stimulation - discomfort
Skeletal muscle contraction
Photo scintillations
RF fields can cause
Heating during scanning - greatest at the surface
SAR
Specific absorption rate - measure of dose of RF E to patient
Quenching
Loss of superconductivity of magnetic field and loss of helium cooling
NSF stands for
Nephrotic systemic fibrosis
Warning signs should be placed at the
5 Gauss line to prevent the exposure of others with pacemakers or electronic implants
What are some implanted devices
Cochlear implants, tissue expanders, ocular prosthesis, dental implants, bone growth stimulators, implanted cardiac defib and implanted drug infusion pumps
Implants that are contraindicated for MRI
pacemakers, aneurysm clips and neuro-stimulators
Magnetic effects can result in
artifacts, rotation/movement of implant, heating of the implant, electrical currents induced in leads, malfunction of implants
