MRI Safety

Question 1

What does static magnetic field mean?

Answer 1

the magnetic field is always on

Question 2

What are the dangers of static magnetic field?

Answer 2

the projectile (attraction of ferromagnetic objects), movement of ferromagnetic implants, magnetic data storage (tapes, credit cards…), and patients with active devices

Question 3

Can RF harm anyone?

Answer 3

it can produce a current in any wire loop, metallic ring/plate. Current in-turn heat the wire or plate, causing a burn

Question 4

What are some things that can heat up from RF?

Answer 4

A ring, gold necklace, bangles, and tattoos with metallic ink

Question 5

What are some MRI screening questions you should ask the patient?

Answer 5

1. Does the patient have a pacemaker?
2. Has the patient undergone operations? If yes, do they have any metallic implants? If yes, it that MR safe?
3. Does the patient have any patches (for drug delivery or otherwise)?
4. Does the patient have any shrapnel in their orbits?
5. Check for body piercing.

Question 6

What implants should you be aware of in MRI?

Answer 6

Pace Makers (old ones are not safe), neuro-stimulators (new ones are now compatible), pumps (old ones not safe, most new ones are), catheters & aneurysm clips (usually safe, but some old ones might not be)

Question 7

What contrast is used in MRI?

Answer 7

salf of Gadolinium in water; administered through intravenous injection

Question 8

What part of the MRI scanner is responsible for the loud noises one hears during the scan?

Answer 8

Magnetic gradient fields

Question 9

The imaging center is divided into 4 zones:
* Zone 1-
* Zone 2-
* Zone 3-
* Zone 4-

Answer 9

• Zone 1: Public access, no restriction
• Zone 2: Unscreened patients (waiting room)
• Zone 3: Screened patients & personnel (have done the MRI safety course and are certified by the institute where they work)
• Zone 4: Screened patients under supervision of trained MRI personnel (scanner rooms)

Question 10

Level 1 MR Personnel

Answer 10

Individuals who have passed the facility’s MR safety educational requirements to ensure that they would not constitute a danger to themselves or others in the MR environment

Question 11

Level 2 MR Personnel

Answer 11

Those who have been more extensively trained and educated in the broader aspects of MR safety issues (MR tech, physicist, & engineers)

Question 12

The square green MR Safe Label is for _.

Answer 12

nonmetallic, nonconducting objects

Question 13

The triangular yellow MR label is for objects with _.

Answer 13

MR Conditional

Question 14

The round red MR label is for _.

Answer 14

MR Unsafe objects

Question 15

What is SAR and what does it stand for?

Answer 15

SAR = Specific Absorption Ratio; The amount of RF power absorbed into the body

Question 16

SAR
* FDA Limit for body is _W/kg averaged over the whole body for _ min.
* FDA Limit for head is _W/kg over the head for _min.

Answer 16

• Body = 2 W/kg; 15 min
• Head = 3.2 W/kg; 10 min

Question 17

On Scanners, what is the Normal Level (normal operating mode) for SAR?

Answer 17

Less than 2 W/kg

Question 18

On Scanners, what is the first level (research/controlled operating mode) for SAR?

Answer 18

Less than 4 W/kg

Question 19

On Scanners, what is the second level (controlled operating mode) for SAR?

Answer 19

Greater than 4 W/kg

Question 20

As magnetic field increases, SAR goes up/down in power scan

Answer 20

up

for 2 times increase in magnetic field, SAR goes up by 4 times

Question 21

Breast MRI is preferably done on the _th - _th day after the first day of menstrual cycle.

Answer 21

7th-10th day

Question 22

If the patient is breast feeding, they need to know that after contrast (Gad) they cannot breast feed for _ days?

Answer 22

two

Question 23

What is contraindicative to Breast MRI?

Answer 23

Expanders; breast implants (silicone & saline) are ok.

Question 24

Though there is no evidence that MRI harms the fetus, as a precaution we do not scan pregnant women on their _ trimester.

Answer 24

1st trimester

Question 25

What is the only semi-invasive MRI scan we do? Why?

Answer 25

MRI for Prostate; The endorectal coil is inserted into the rectum and stays there for the study . The coil is held in place by filling the balloon with air (pressure); need to administer Glucagon