Dr/Ahmed Bahnassy

Consultant Radiologist

The MRI site is divided into 4 zones:

Zone I – It is outside the MR environment and is freely accessible to the general public.

Zone II – Interface between uncontrolled Zone I and controlled zones III & IV, in which patients are received and screened.

Zone III – In which static magnetic field’s strength is >5G. It should be clearly demarcated and access to it is strictly restricted, under the supervision of MR personnel, because free access to it by unscreened people, ferromagnetic objects, or equipment can result in serious injury or death.

Zone IV – MR scanner room itself, clearly demarcated as being potentially hazardous and it is directly observed by MR technologist. In case of cardiac or respiratory arrest or other emergencies in Zone IV, MR personnel should initiate CPR while the patient is being immediately removed from Zone IV.

All individual working in Zone III should complete at least one MR Safety Lecture which should be repeated at least annually.

There are 2 levels of MR Personnel:

Level I Personnel will have minimal safety educational effort to ensure their own safety as they work in Zone III.

Level II Personnel will have more training and education to deal with thermal loading and burns and neuromuscular excitation from changing gradiant.

General precautions

All patients and non MR personel should be screened before entering Zone III.

No one should enter the bore of MR imager during MR process.

Non-MR personnel should be accompanied by or under the immediate supervision of MR Personnel in Zones III & IV.

Patients and their accompanying, non-MR personnel should be screened at least once.

General precautionsAny individual undergoing MR procedures must remove all readily removal

metallic objects or particles.

Prior to entering Zone III, every individual with a history of potential ferromagnetic foreign object penetration must undergo further investigation (past history, plain x-rays, prior CT or MR examination, written documentation, written testing of the implant, product labeling, and/or peer-reviewed publication regarding MR compatibility and safety.)

In case of prior orbit trauma by a potential ferromagnetic foreign body, the orbits must be cleared by x-rays, or contiguous CT slices if previous x-rays, CT or MR orbit done after the trauma is not available.

Conscious patient or family member of unconscious patient should complete written MR Safety Screening Questionnaires prior to enter Zone III.

aneurysmal clip precautions

Particular screening for an intracranial aneurysm clip.

In case of MR examination is urgently needed while no reliable patient metal exposure can be obtained, one or more of the following investigations is / are needed.

• Previous x-rays, CT or MR• Physical examination of the patient to look for entrance

of ferromagnet foreign body implant.• X-rays for skull, orbit and chest.

Thermal injury precautions

Monitoring unconscious or sedated patient for thermal injury can be performed by physical examination after each image sequence or putting cold compress or ice upon all necessary electrically conductive material that touch the patient during scanning.

Time varying radiofrequency magnetic field-related issues

All unnecessary or unused electrically conducted material should be removed from MR system, because current can be induced within them during scanning and this might result in heating.

No large caliber, electrically conductive loops including patient issue (arm or legs) are allowed in MR scanner because it is possible that resonant circuitry between RF and the lead which may result in rapid heating.

Swan-Ganz and Foley catheter are at risk for MR.

If wires are necessary to be in the bore, they should be as far as possible from inner wall of the bore and if they touch the patient, they should be separated from the patient by pads.

Patient tissues should not touch inner bore.

If non-ferromagnetic skin staples are within the irradiated region by RF, they may heat. Patient should be aware or staples covered by cold compress.

Drug-delivery patches and pads

Some drug-delivery patches contain metallic foil may cause thermal injury. The delivered dose may be altered if patch is removed or repositioned. Case to be discussed with physician or foil covered by cold compress.

Cardiac patients precautions

Any individual with implanted cardiac pacemaker, auto-defibrillator; diaphragmatic pacemaker, or other electromechanically activated device should be precluded from Zone IV and restrained from Zone III.

Prisoners precautions

Prisoners with metallic device or RFID tracking bracelet should be accompanied by an appropriate authorities who can and will remove the device prior to MR study and replace it after examination.

Fire precautions

Assigning appropriately trained security personnel to be the 1st (first) called person in case of fire, cardiac arrest in MR site. He will join MR unit before firefighter and code blue team and will guide them at their arrival.

MR site should be provided with MR compatible fire extinguishing equipment stored in Zones III & IV.

If there is a fire and Zones III & IV needs to be entered by firefighter or emergency response personnel and their equipments, quenching the magnet should be considered. Firefighter can enter after being sure that magnetic field is no longer detectable.

Pregnancy Related IssuesHealthcare practitioner pregnancies: Pregnant healthcare practitioner are permitted to work in and around

MR environment but not to remain within the MR scanner bore or Zone IV during scanning.

Patient pregnancies:• Pregnant patients can undergo MR scan when: the information

requested from MR cannot be acquired by ultrasound, will affect the care of the patient or fetus during pregnancy and cannot be delayed until the patient is no more pregnant.

• Pregnant patient should sign consent.• Fetal MR contrast agents can pass placental barrier and should

not be used except if benefits overweighs risks.

Pediatric MR Safety Concerns

Sedation and monitoring issues: Sedation is given by anesthesia staff or pediatric clinic

and according to anesthesia guidelines: Child should be fasting, monitored during and after procedure. Chloral hydrate can be prescribed by pediatrician and given by MR nurse. Resuscitation equipment including oxygen and suction should be available.

Pediatric screening issues: Children clothes should be removed and replace by

gown before entering Zone IV.

MR safety of accompanying family and personnel.