Magnetic Resonance Imaging (MRI) SAFETY, Study notes of Magnetic Resonance Imaging (MRI)

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Magnetic Resonance

Magnetic Resonance

Imaging (MRI) SAFETY

Imaging (MRI) SAFETY

Charlie Dziedzic, Ed McNamara, Dan Richardson, RadiologyJudy Smith, Staff DevelopmentApril 2008

Goal and Objectives

Goal and Objectives

GoalThis course will enable the learner to provide a safeenvironment for patients and staff who are in the presenceof the MRI scanner.Objectives1.

Describe basic knowledge of magnetic fields and theirinfluence on objects near them.

Describe the importance of safety when working aroundthe MRI scanner.

Identify precautions that should be taken to avoid accidentswhen working near the MRI scanner.

Identify precautions that should be taken when patientshave implantable devices or metallic foreign bodies.

The MRI Magnet

The MRI Magnet

Most people have had some experience with naturalmagnets and their attractive forces (e.g., in science classes,by playing with them or by using a magnet to attach papersto a refrigerator door). The MRI scanner is a large magnet (10,000lbs.) with a tremendously strong magneticpull. The magnet in the MRI scanner createsa force field which can affect objects that areclose to it. As you approach the MRI scanner,the attractive force field increases rapidly. This strong magnetic field can have adverse effects on patientsand staff who are within the scanner’s magnetic force field.

• An object that is attracted

by a magnet and which canbecome magnetized itself.

Magnetic Field Hazards

Magnetic Field Hazards All MRI magnets have a magnetic fieldthat extends into the exam room.Anyone entering the MRI scannerroom will be exposed to the magneticattraction of the scanner. The closeryou get to the scanner, the strongerthe magnetic pull.Any

ferromagnetic object

• brought into

the MRI scanner room will becomemagnetized and can become a… Dangerous Projectile!

Examples of Ferromagnetic Objects: Ferromagnetic metal alloys usually contain iron

, nickel

or

cobalt

. These elements are found in most metal objects.

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

z

Delayed patient care…It takes 4 days to remove theobject and to re-power the scanner!

z

Possible injury to patient or staff.

z

Possible damage to the MRI scanner.

z

Approximate cost due to each “missile effect” incident:

Results of The Missile Effect:

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

Contribute page

Displacement and Heating of Surgical Implants:

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

z

Cardiac pacemakers

z

Neurostimulators

z

Pain control pumps

z

Penile implants

z

Cochlear implants

Displacement andheating of theseimplants may cause alife-threatening situation!

Electromagnetic Interference with Electronic Devices:

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

Mechanically or electrically activatedimplants may stop or malfunction in thepresence of the MRI magnetic field.Patients with pacemakers have diedduring or shortly after MRI exams due todisruption of pacemaker function by theMRI system.Hospital staff with pacemakers or otherimplanted electronic devices could alsobe affected, if they come within the strongmagnetic field of the MRI.

Body Piercing Jewelry:

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

Risks for these patients include: z

Discomfort or painful sensations due topossible displacement (movement) of thejewelry.

z

Patient burns due to heat generated fromthe interaction between the jewelry andthe electromagnetic fields.

All patients with body piercing jewelry must be screened

for jewelry removal before they have their MRI scan!

All patients with tattoos must be screened

before they have their MRI scan.

Many patients scheduled for an MRIscan will present with tattoos.These tattoos will be either cosmeticor decorative and can be locatedanywhere on the body.Some of these tattoos will containferromagnetic material which cancause heating, swelling, or burningat the tattoo site.

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

Tattoos:

The MRI Magnet is …

The MRI Magnet is …

Always

Always

Always

Always

Always

Always

On!

On!

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

The Policies, Guidelines, andRecommendations for MRI Imaging, Safetyand Patient Management

issued by the

Safety Committee of the Society for MRIimaging states: “MRI may be used for pregnant women ifother non-ionizing diagnostic imaging isinadequate or if the MRI provides importantinformation that would otherwise requireexposure to ionizing radiation (CT,fluoroscopy, etc.)”

Magnetic Field Hazards

Magnetic Field Hazards

(cont.) (cont.)

Pregnancy:

(cont.)

All pregnant patients must be screened before they have their MRI scan.

Summary of MRI Hazards

Summary of MRI Hazards

Hazard

Possible Danger

Body-piercing jewelry

Displacement, Heat

Transdermal skin patches

Burning

Tattoos

Burning

Aneurysm clips

Displacement

Stents

Displacement

Cochlear implants

Displacement

Penile implants

Displacement