Instead of x-rays and radiation, MRI uses a strong magnetic field and radio frequencies to produce the images. Unlike a CT or x-ray, the MR system magnet is ALWAYS on.
Missile Effect:
Any ferromagnetic material will be attracted to the magnetic. Scissors, IV poles, monitors and stretchers have “flown” through the air to the magnetic. Several years ago in the USA, a child was killed when an oxygen cylinder was carried into the magnet room, and flew into the magnet crushing him.
Burns:
Alternating magnetic fields used during the exam can induce electrical currents in conductive materials, cables and wires. Reports of first, second, and third degree burns have been associated with the use of ECG wires and pulse oximeters. A report was submitted to the FDA of a swann ganz catheter tip melting in a patient.
Contraindications
The strong magnetic field may be hazardous to individuals (patients and staff) entering the MR room if they have not been screened by MR staff for contraindications. Contraindications include pacemakers that may be turned off, metal chips in eyes that may heat up or move, and ferromagnetic aneurysm clips that may be pulled off a vessel.
Exam length = 30 – 90 min
MR scan room door must be shut during the actual scans (2-7 min each). If the door is opened during the scan, information may be lost. Staff may not continually enter and leave scan room. If necessary, staff may leave the magnet room to check IVAC etc, however door must be shut tightly again before the next scan is started.
Visual access of patient is restricted – area being scanned is centered within a 4-foot long tube.
Patient Preparation:
IVAC’s may not enter the MRI room. If patient must remain on IVAC, 5 extension sets must be added.
MR Checklist: must be completed. If there are any questions regarding possible contraindications, contact MRI staff at ext. 35159 (UC) or 52207 (WC).
External Fixation Devices: most are magnetic and need to be removed.
Swan Ganz: must be removed
Trachs: metal trachs must be replaced with plastic
Clamps: any metal clamps on chest tubes etc, must be replaced with plastic
Ventilator Circuit: respiratory therapy should bring over there own supplies and re-circuit the vent when they are finished.
Staff Preparation:
staff monitoring the patient during MR may not be pregnant
ensure staff have no other contraindications (aneurysm clips, pacemakers, cochlear implants, metal chips in eyes)
leave wallets, change, in CCTC
Available for use during the MR exam:
ventilator (monaghan 225 ventilator – to be replaced with the BMD 1C-2A)
pulse oximeter
blood pressure
oxygen
suction (between scans)
1 MR pressure bag (to replace tyco)
MR compatible stethoscope
anesthesia (if prearranged with anesthesia dept)
Unavailable
ECG
Invasive BP
Arterial line
Temperature
Available for use during the MR exam:
Ventilator (BMD 1C-2A)
Millennia Monitor which provides:
ECG
N20
NIBP
Pulse Oximeter
ETCO2
Invasive Blood pressures (2)
Respiration
Stethoscope
oxygen
suction (between scans)
anesthesia (if prearranged with anesthesia dept)
Unavailable
Arterial line
Patient:
ecg lead wires must be removed
tyco must be replaced with MR pressure bag
monitoring equipment used for transfer must be removed
backboard – all backboards have metal in them for support. Backboard must be removed
Staff
Remove all metal e.g. ID badges (with magnetic strips), beepers, watches, costume jewelry, etc.
remove all objects from pockets (including pens, scissors)
patient’s chart may not enter room
Ensure equipment and belongings are not placed under stretcher or blankets. They could become projectiles and cause serious injury to the patient or staff.
Information from MR tech
use of oximeter
set BP to auto if required
tech will inform you how to contact them during scan
tech will inform staff remaining in magnet room on how to remove patient from magnet bore if there is an emergency
