10) Imaging

Question 1

Advantages of MRI

Answer 1

• No ionizing radiation
• Contrast dye usually doesn’t cause side effects
• Non-invasive
• Great resolution & contrast regardless of tissue thickness
• Good detail even w/out contrast
• Works in any plane

Question 2

Disadvantages of MRI

Answer 2

• Can’t do if pt has metal in their body
• Can’t do on pregnant women
• Not good for looking at bone
• Some pt’s are claustrophobic
• Obese pt’s can’t fit in the machine
• Kids will prob need to be sedated
• Pt needs to stay completely still
• Noisy
• Expensive
• Time-consuming
• Sometimes there’s a waitlist

Question 3

MRA

Answer 3

Used to image blood vessels to eval for stenosis, aneurysms, AVM, etc

Question 4

fMRI

Answer 4

Displays metabolic activity of the brain by measuring the BOLD level Hgb)

Question 5

Why does fMRI work?

Answer 5

Hgb is dimagnetic when oxygenated, but paramagnetic when deoxygenated so imaging results change based on O2 levels

Question 6

Strengths of fMRI

Answer 6

• Non-invasive
• Replicable
• Good spatial localization
• Well validated

Question 7

Limitations of fMRI

Answer 7

• Mediocre temporal resolution
• Complex & highly variable analyses
• Time consuming
• Expensive

Question 8

EEG

Answer 8

Detects electrical activity in the brain using electrodes placed on the scalp to dx epilepsy & sleep disorders

Question 9

True or False: EEG is non-invasive but isn’t as spatially accurate as fMRI is.

Answer 9

True

Question 10

PET scan

Answer 10

Maps brain fxn’ w/injectable tracers to look at glucose metabolism in the brain to detect CA, dementia, & seizures

Question 11

Strengths of PET scan

Answer 11

• Simple physiologic mechanism
• Provides absolute, quantitative data
• Allows imaging of anything that can be tagged

Question 12

Limitations of PET scan

Answer 12

• Poor temporal & spatial resolution

* Requires radioactive injections

Question 13

How does MRI work?

Answer 13

Pt gets injected w/contrast dye & the dye moves around at different speeds

Question 14

What is MRI good at dx’ing?

Answer 14

• MS
• Strokes
• Neuro infections
• Tumors
• Tendonitis
• Torn ligaments
• Disc problems

Question 15

W/a T1 weighted MRI, how will tissues w/fluids & tissues w/fat appear?

Answer 15

Tissues w/fluid=Dark

Tissues w/fat=Bright

Question 16

W/a T2 weighted MRI, how will tissues w/fluids & tissues w/fat appear?

Answer 16

Tissues w/fluid=Bright

Tissues w/fat=Dark

Question 17

Why is T2-weighted MRI good for looking at pathologies?

Answer 17

Bc damaged tissues tend to devo edema, so the area will be illuminated

Question 18

What is a CT scan good for?

Answer 18

Looking at the brain

Question 19

What can be used to make organs more visable on a CT scan?

Answer 19

Contrast dye

Question 20

On a CT scan, what color will bone, tissues, & liquids/gases be?

Answer 20

Bone=White
Tissue=Gray
Gasses & Liquids=Black

Question 21

What does a CT scan image correspond to?

Answer 21

3D section of the pt

Question 22

True or False: CT scans look at structure rather than fxn.

Answer 22

True