MRI Sequences

Question 1

STIR MRI helpful for what

Answer 1

• spine, MSK imaging, brachial/lumbar plexus, abdominal, chest imaging, tumor detection
• tumor detection
• stress fractures: edema in bone has high signal
• fat-suppressed
• water/fluid has a high signal intensity

Question 2

Advantages of STIR MRI

Answer 2

• great contrast resolution
• use with low field strength magnets

Question 3

Disadvantages of STIR MRI

Answer 3

• hemorrhage and protein-rich fluid may be suppressed
• cannot be used after contrast injected
• low signal to noise ratio (image is grainier)

Question 4

What is FLAIR MRI helpful for?

Answer 4

Brain and spine imaging
- infarction
- demyelination (MS)
- meningitis and other infections
- TBI/head trauma

Question 5

FLAIR MRI characteristics

Answer 5

FLAIR
- fluid suppressed (darker)
- high signal indicates a pathological process
- CSF appears dark, while edematous (swelling caused by excess fluid) tissue appears bright

Question 6

What is proton density (PD) weighted MRI good for?

Answer 6

Helpful with brain and MSK imaging in the extremities (especially joints)
- discriminates well between fluid, hyaline cartilage, and fibrocartilage

Question 7

Proton density (PD) weighted MRI characteristics

Answer 7

• tissues with a high density of protons have higher signal
• fats and fluids have a high signal intensity (bright)

Question 8

MRI contraindications

Answer 8

• ferromagnetic surgical clips
• pacemakers/implanted electronic devices (insulin pump)
• intra-ocular metallic foreign bodies
• certain types of cochlear implants
• metallic catheters
• halo vests
• pacing leads

Question 9

MRI relative contraindications

Answer 9

• some artificial heart valves
• metallic foreign bodies (bullets/pellets, shrapnel)
• unstable patients
• pregnancy
• piercings
• tattoos < 6 weeks old in the area of interest