Notes

Question 1

Four Components of MRI?

Answer 1

1. Magnetic Field
2. Radio Frequency
3. Gradient Coils
4. Cryogens

Question 2

Problem with magnetic field?

Answer 2

1. Invisible
2. Pulls in Translational Force (missle effect)
3. Pulls in Torque force (twist effect)

Question 3

Two types of pull?

Answer 3

Translational and Torque

Question 4

What is the point of no return?

Answer 4

The point where the magnetic force pulls in a ferromagnetic object and would be unable to be stopped.

Question 5

Fringe Field

Answer 5

The stray magnetic field outside the bore of the magnet is known as the fringe field and this is a 3 dimensional field measured in Gauss. MRI systems are shielded to confine the fringe field within the scan room.

Question 6

How is the edge of the fringe field restricted so it doesn’t spill into adjacent rooms?

Answer 6

Active Shielding

Question 7

Active Shielding

Answer 7

Brings in the fringe field through increasing tesla by coil use.

-the magnetic field can be neutralized by another instrument which emits an opposite magnetic field of equivalent value, thus eliminating the residual field in a limited space.

-5 gauss line is where it is safe for someone not screened for MRI (LCNI)

Issue: acceleration of metal objects is further multiplied

Question 8

Benefits of shielding

Answer 8

1. MRI can be in smaller space/room
2. Edge of fringe field brought closer to the MRI magnet

Question 9

End of the fringe field?

Answer 9

Called the 5 gauss line

Question 10

Radio Frequency Issues

Answer 10

heating (SAR), conductance, materials (loop in cord, skin on skin)

Question 11

MRI radiofrequencies are just as dangerous as xrays or ct scans

Answer 11

False

Question 12

SAR

Answer 12

Specific Absorption
weight

Question 13

RF energy

Answer 13

-Absorbed by tissue –> heat accumulated within subject

Question 14

Gradient Coils

Answer 14

-Deliberate variation to magnetic field
-Extreme noise (EPI)
-Peripheral Nerve Stimulation (tingly/painful)

Question 15

To prevent peripheral nerve stimulation

Answer 15

Make sure arms & legs aren’t crossed. Make sure to bring participant out of machine if stimulation continues.

Question 16

Cryogens

Question 17

Quench

Answer 17

-releases the helium immediately, heating up the superconductive coil and dropping the magnetic field in a matter of minutes
Could cause frost bite
-Quench leak could lead to asphyxiation hazard
-Ear drum rupture
-Fire hazard

Question 18

When to Quench

Answer 18

Only Quench if life or limb are in danger
–Take participant out of room
–Contact MRI manufacturer to refill helium

Question 19

Liquid helium runs through power, keep liquid helium cold

Answer 19

True

Question 20

Has anyone ever been killed from MRI

Answer 20

yes

Question 21

Biggest danger for anyone in MRI enviornment?

Answer 21

Metal being pulled in?

Question 22

Paperclip/bobby pin can reach

Answer 22

40 mph before reaching center of magnet

Question 23

Would power outage make MRI lose magnetic field?

Answer 23

No

Question 24

Before going to magnet bay what should safety trained staff do

Answer 24

pat themselves down, do checks to ensure they didn’t forget anything (like bobby pins)

Question 25

Your subject arrived early, what to do?

Answer 25

1. Have subject spin on the ferromagnetic detector and troubleshoot any red lights 2. Remind the participant of the length of the scan and encourage them to use the restroom 3. Remove all piercings, jewelry, or items in pocket. Place in locker. 4. Give the scan operator the screening form so they can type the participant information 5. Remove any antimicrobial materials

Question 26

Manufactures claim to produce anti-bacterial clothing. What is in this clothing? Is it safe to scan someone who is wearing this material?

Answer 26

-Lulu lemon/under armor -copper/silver -no, it could heat up and burn participant

Question 27

Ferromagentic detector

Answer 27

Only detects ferromagnetic items (won't detect clothing with copper/silver so make sure to check).

Question 28

Gradient Coils

Answer 28

Creates magnetic field that turns on/off quickly and fights with magnetic field, very loud

Question 29

What secondary effect can these magnetic fields turning on and off cause in human bodies?

Answer 29

Hearing loss

Question 30

Why is it important we collect correct height and weight accurately on screening form? What could happen if height and weight aren't accurate?

Answer 30

SAR (Specific Absorption Rate) based on H/W that allows us to know how much RF they can be exposed to. If H/W not accurate, they could be over exposed to RF their body can't handle.

Question 31

If you have to scan a larger participant and their elbows bump agains the inside of the scanner bore, what steps should be taken to protect subject? what are you trying to protect?

Answer 31

Use 1cm pad to separate and insulate from direct contact. Otherwise, they could get burned.

Question 32

What is the #1 concern of liquid helium with regard to anyone in the room?

Answer 32

Asphyxiation from helium displacing all the oxygen from the room.

Question 33

How will participant get your attention during scan?

Answer 33

Participant can use the squeeze ball.

Question 34

If your participants scan looks abnormal to you, what should you do?

Answer 34

Let scan operators know so they can send it to the appropriate individuals to get it checked out.

Question 35

If participant has medical implant what needs done before MRI is scheduled?

Answer 35

1.Email LCNI staff to ensure if surgery/implant is safe. 2. Have the subject contact the medical facility to acquire implant records 3. Have participant acquire make and model of the implanted device to verify implant safety. 4.Make note of the implant and communicate with LCNI before the participant is scheduled.

Question 36

Some people don't know or forgot if they were claustrophobic

Answer 36

True

Question 37

How many safety trained individuals are needed for a scan session in research? Is it better to have more?

Answer 37

2 are required, 3 is acceptable, more than that is discouraged/ (not allowed)? due to potential distractions.