MRI for the physical assistant

Question 1

MRI uses strong magnetic field to manipulate the electrical activity of ?

Answer 1

hydrogen atoms

Question 2

MRI are looking at ?

Answer 2

Protons

Question 3

The movement of protons causes a ? This produces ?

Answer 3

electrical current magnetic field

Question 4

The magnet of the MRI is always?

Answer 4

On

Question 5

Protons line up?

Answer 5

parallel to main superconducting magnent

Question 6

Transmitter coils send short magnetic pulse ?

Answer 6

RF pulse which changes a orientation of protons (makes them stand a certain way)

Question 7

T1 images mean ?

How do they appear?

Answer 7

-Relaxtion (recovery)

-Time it takes for the tissue to recover to parallel state

Question 8

T2

Answer 8

• Relaxation (decay)
• Time it takes for tissue to return to perpendicular to magnetic feild

-water and tumor appear white

Question 9

Things in T2 weighted images that typically appear white ?

Answer 9

• water
• fat
• edema
• inflammation
• infection
• cysts
• hemorrhage

Question 10

What do you use MRI’s for?

Answer 10

• Musculoskeletal
  
  • ligament cartilage/meniscus;
  • infection/abscess
  • tumor/mass (hallmark for spotting this)
• Neurological
  
  • HNP
  • infectionabcess
  • nerve impingement
• GI
• Endocrine
• Gyno/urologic

Question 11

WHY MRI?

Answer 11

• Non-invasive
• No known harmful effects
• Can provide soft tissue characteristics
  
  • superior to CT
  • ideal exam choice for brain, spine, joints

Question 12

MRI is primarily used for ?

Answer 12

• Soft tissue evalution
  
  • tumor infection
• Also diagnosing occult fractures
• Modality of choice for disc hernation

Question 13

Most MRI scanners have Magnetic Field Strength of ?

Answer 13

• 0.5-3 Tesla (T)
  
  • open MRI (0.1-1.0 T)

Question 14

1. Are closed or open MRI scanners better?
2. Open MRI’s are better for?

Answer 14

1. higher quality image with closed
2. heavier pt’s

Question 15

MRI Coils are responsible for ?

Answer 15

• transmitting pulses
• recieving the signal
• loud bangy noise lol

Question 16

What is the MRI contrast medium and what is the purpose of it?

Answer 16

• Gadolinium
• helps yeild a brighter signal and its clinically helpful for
  
  • tumor infections and inflammation

Question 17

What is the side effect potentional of MRI Gadolinium ?

Answer 17

• Nephrogenic Systemic Fibrosis
  
  • rare, seen in patients with severly impaired renal function

Question 18

1. What is MRI suppression?
2. ‘Fat-supression’ fat will appear?

Answer 18

1. Feature of MRI allowing
   
   • cancel out/eliminate signals from certain tissues
     
     • typically ‘fat-supressed’
2. ‘Fat-supression’ fat will appear dark on T1-weighted images

Question 19

MRI vs. CT?

Answer 19

Question 20

MRI Disadvantages ?

Answer 20

• Long scan time (30-45 mins– a lot longer than a CT)
• Exspensive
• implanted devices and metallic foreign bodies
• anxiety filled pt
• Pregnancy
• obese pt

Question 21

In order to get an MRI prior auth. your clinical note needs to include?

Answer 21

• ROS
• PE findings
• treatment to date
• document of failure of treatment
• document worsening scenario