MRI safety is a complex topic due to variations in hardware, patients, and implanted devices. Metallic objects can be dangerously attracted to the strong magnetic field. Patients must remove all metal before an MRI and inform staff about any implants. Zoning the MRI facility and carefully screening patients helps ensure safety in the magnetic environment.

1. MRI SAFETY
MR. ROHIT BANSAL
ASSISTANT PROFESSOR (RADIO-PHYSICS)
MAMC(AGROHA)

3. MRI safety is a convoluted subject. Over the last 20 years, the
field of MRI has increased greatly in complexity. Scanners now
operate at a wide range of field strengths and manufacturers
offer different machine configurations, some of which operate
with powerful and rapidly switching gradient magnetic fields.
Coil design, magnet bore width, and other factors also vary
across different platforms. In addition to variations in
hardware, patients present with a diverse variation in body
habitus and an increasing variety of implanted devices and
cosmetic body jewellery. Implanted devices may be
conditionally safe below a certain field strength, spatial
gradient magnetic field, or specific absorption rate (SAR). As a
result, there are many combinations of factors that could
potentially contribute to a safety hazard.

4. The powerful magnetic field of the MR system can attract
objects made from certain metals (i.e., metals known to be
ferromagnetic, such as iron) and cause them to move suddenly
and with great force. This can pose a possible risk to the
patient or anyone in the object's "flight path." Therefore, great
care is taken to ensure that external objects such as
ferromagnetic screwdrivers and oxygen tanks are not brought
into the MR system room.
As a patient, it is vital that you remove all metallic belongings
in advance of an MRI examination, including external hearing
aids, watches, jewelry, cell phones, and items of clothing that
have metallic threads or fasteners. Additionally, makeup, nail
polish, or other cosmetics that may contain metallic particles
should be removed if applied to the area of the body
undergoing the MRI examination.

5. Various clothing items such as athletic wear (e.g., yoga pants,
shirts, etc.), socks, braces, and others may contain metallic
threads or metal-based anti-bacterial compounds that may
pose a hazard. These items can heat up and burn the patient
during an MRI. Therefore, MRI facilities typically require
patients to remove all potentially problematic clothing items
prior to undergoing an MRI.
The powerful magnetic field of the MR system will pull on any
ferromagnetic object in or on the patient’s body such as a
medical implant (e.g., certain aneurysm clips, medication
pumps, etc.). Therefore, all MRI facilities have comprehensive
screening procedures and protocols they use to identify any
potential hazards. When carefully followed, these steps ensure
that the MRI technologist and radiologist know about the
presence of any metallic objects so they can take precautions
as needed.

6. In some unusual cases, due to the presence of an unacceptable
implant or device, the exam may have to be canceled. For example,
the MRI exam will not be performed if a ferromagnetic aneurysm clip
is present because there is a risk of the clip moving and causing
serious harm to the patient. Besides possible movement or
dislodgement, certain medical implants can heat substantially during
the MRI exam as a result of the radio waves (i.e., radiofrequency
energy) used for the procedure. MRI-related heating may result in an
injury to the patient. Therefore, as a patient, it is very important for
you to inform the MRI technologist about any implant or other
internal or external object that you may have prior to entering the
MR scanner room.
The powerful magnetic field of the MR system may damage an
external hearing aid or cause a heart pacemaker, electrical
stimulator, or neurostimulator to malfunction or cause injury. If you
have a bullet or any other metallic fragment in your body there is a
potential risk that it could change position and possibly cause an
injury.

7. In addition, a metallic implant or other object may cause signal loss or
alter the MR images making it difficult for the radiologist to see the
images correctly. This may be unavoidable, but if the radiologist
knows about it, allowances can be made when obtaining and
interpreting the MR images.
For some MRI exams, a contrast material known as a gadolinium
contrast agent may be injected into a vein to help improve the
information seen on the MR images. Unlike the contrast materials
used in x-ray exams or computed tomography (CT) scans, a
gadolinium contrast agent does not contain iodine and, therefore,
rarely causes an allergic reaction or other problem. However, if you
have a history of kidney disease, kidney failure, kidney transplant,
liver disease, or other conditions, you must inform the MRI
technologist and/or radiologist before receiving a gadolinium
contrast agent. If you are unsure about the presence of these
conditions, please discuss these matters with the MRI technologist or
radiologist prior to the MRI examination.

8. Items that need to be removed by patients and individuals
before entering the MR system room include:
 Purse, wallet, money clip, credit cards, cards with magnetic
strips
 Electronic devices such as beepers, cell phones,
smartphones, and tablets
 External hearing aids
 Metallic jewelry and watches
 Pens, paper clips, keys, coins
 Hair barrettes, hairpins, hair clips and some hair ointments
 Shoes, belt buckles, safety pins
 Any article of clothing that has metallic fibers or threads,
metal-based antibacterial compounds, metallic zippers,
buttons, snaps, hooks, or underwire

9. Objects that may interfere with image quality if close to the area being
scanned include:
 Metallic spinal rod
 Plates, pins, screws, or metal mesh used to repair a bone or joint
 Joint replacement or prosthesis
 Metallic jewelry including those used for body piercing or body
modification
 Some tattoos or tattooed eyeliner (these alter MR images, and there is
a chance of skin irritation or swelling; black and blue pigments are the
most troublesome)
 Makeup (such as eye shadow and eyeliner), nail polish or other cosmetic
that contains metal
 Dental fillings or braces (while usually unaffected by the magnetic field,
these may distort images of the facial area or brain; the same is true for
orthodontic braces and retainers)

11. • 300 series Stainless steel

12. The question of anxiety or claustrophobia
Some patients who undergo MRI examinations may feel confined,
closed-in, or frightened. Perhaps one out of every twenty people may
require a mild sedative to remain calm. Some MRI centres permit a
relative or friend to be present in the MR system room, which also has
a calming effect for the patient. If patients are properly prepared and
know what to expect, it is almost always possible to complete the
examination.
Pregnancy and MRI
If you are pregnant or suspect you are pregnant, you should inform the
MRI technologist and/or radiologist during the screening procedure
that is conducted and before the MRI examination. In general, there is
no known risk of using MRI in pregnant patients. However, MRI is
reserved for use in pregnant patients only to address very important
problems or suspected abnormalities. In any case, MRI is safer for the
foetus than imaging with x-rays or computed tomography (CT).

13. Breast-feeding and MRI
You should inform the MRI clinic that you are breast-feeding
when scheduling your MRI exam. This is particularly
important if you receive and MRI contrast agent. One option
under this circumstance is to pump breast milk before the
MRI exam, which can be used to feed the infant until the
contrast agent has been cleared from the body. It usually
takes about 24 hours for the contrast agent to clear the body.
The clinic or radiologist will provide additional information to
you regarding this matter.

14. Safety zones
The American College of Radiology (ACR) has published a
guidance document on MRI safety that makes
recommendations related to policy and practice in the field. One
of the key recommendations is that the MRI facility should be
zoned according to risk. The zones are represented as a floor
plan in Figure. The aim of using zones is to prevent unauthorized
access to areas where the high magnetic field may cause injury
or death.The ACR defines the zones as follows:
• Zone I. “…all areas that are freely accessible to the general
public. This area is typically outside the MR environment itself
and is the area through which patients, healthcare personnel,
and other employees of the MR site access the MR
environment.”

15. • Zone II. “…the interface between the publicly accessible,
uncontrolled Zone I and the strictly controlled Zones III and IV.
Typically, patients are greeted in Zone II and are not free to move
throughout Zone II at will, but are rather under the supervision of
MR personnel. It is in Zone II that the answers to MR screening
questions, patient histories, medical insurance questions, etc. are
typically obtained.”
• Zone III. “…the region in which free access by unscreened non-MR
personnel or ferromagnetic objects or equipment can result in
serious injury or death as a result of interactions between the
individuals or equipment and the MR scanner’s particular
environment. These interactions include, but are not limited to,
those involving the MR scanner’s static and time-varying magnetic
fields. Zone III regions should be physically restricted from general
public access by, for example, key locks, passkey locking systems, or
any other reliable, physically restricting method that can
differentiate between MR personnel and non-MR personnel.”

16. • Zone IV. “…the physical confines of the room within which the MR
scanner is located. Zone IV should also be demarcated and clearly
marked as being potentially hazardous due to the presence of very
strong magnetic fields. Zone IV should be clearly marked with a red
light and lighted sign stating: The Magnet is On. Except for resistive
systems, this light and sign should be illuminated at all times and
should be provided with a backup energy source to continue to
remain illuminated for at least 24 h in the event of a loss of power to
the site.”

19. Quenching is the process whereby there is a sudden loss of absolute zero of
temperature in the magnet coils, so that they cease to be super conducting and
become resistive, thus eliminating the magnetic field. This results in helium
escaping from the cryogen bath extremely rapidly. The helium, which is turned into
gas during a quench, is released. A properly set up MRI room will contain
emergency venting systems to safely remove the helium gas from the room.
A quench is an event that occurs only in superconducting magnets and results in a
loss of magnetic field of the MRI magnet. It is caused by a loss of superconductivity,
a rapid increase in the resistivity of the magnet coil windings, which generates heat
that results in rapid evaporation, or boil-off of the magnet coolant. There are two
situations in which quench may occur:
a) Spontaneously due to some force or disruption to the magnate system.
b)The emergency “Magnet Stop” button is pressed during emergency situation.
A non-spontaneous quench (e.g., a quench requested by a user in the case of an
emergency) takes anywhere from 10 -60 seconds, depending on the manufacturer
(the magnet current is passed through a resistor and allowed to dissipate, boiling
off much less helium).
Quenching

21. Emergency Magnet Rundown Unit: This initiates a controlled
quench and turns off the magnetic field. It is typically a big red button
located on the wall of the magnet room near the door. This button
should only be used in a life threating situation. Pressing this button
makes the scanner out of service costing heavily for replacing lost
liquid helium.
Emergency shutdown: Does not quench the magnet but turns off
most electrical power in the scanner room and operator area,
including the console, computers, patient table, ups etc. It may be
simple red button labelled or unlabelled This switch should be used
when there is serious equipment fault or hazard, such as fire, water in
the vicinity of the MR scanner.
EMERGENCY STOP BUTTON

23.  The 5 gauss line is the safety line drawn around the perimeter of the
main magnet of the MRI scanner, specifying the distance at which the
stray magnetic field is equivalent to 5 gauss (0.5 mT).
 Five gauss and below are considered 'safe' levels of static magnetic field
exposure for the general public.
 At 5 gauss and above:
1. cardiac pacemakers and other implanted electronic devices are at risk
of being interfered with by the static magnetic field
2. ferromagnetic materials may become projectile (and are thus
prohibited from crossing the 5 gauss line)
 Note that the distance at which a 5 gauss line is drawn around a
particular MRI scanner will depend on magnet strength and the level
of magnetic shielding used.
5 gauss line

25.  A Faraday cage or Faraday shield is an enclosure used to
block electromagnetic fields. A Faraday shield may be
formed by a continuous covering of conductive material or
in the case of a Faraday cage, by a mesh of such materials.
 Faraday cages come in all shapes and sizes, but all of them
use a metal screen that conducts electricity, creating a
shielding effect.
FARADAY CAGE

29.  1st MRI accident occurred in New-York area hospital in 2001
July . A six year old boy , Michael Colombini lost his life when
the machine's powerful magnetic field jerked a metal
oxygen tank across the room, crushing the child's head.
 In India latest MRI accident that took a life of a person
named Rajesh Maru happened in 2018 in Nair hospital
Mumbai.
MRI ACCIDENT

30. Accident at Nair Hospital ,Mumbai

31. MRI Machine At Lohiya Hospital Pulls UP
textile Minster Satyadev Pachauri's guard’s
PistolWhen He Came For MRI

33. “MRI CANTURN INTO MONSTER ,IT IS IN OUR HANDTO STOP
DISASTER”