Neuro Imaging

Question 1

What is a CAT/CT scan?

Answer 1

Uses thousands of xray beams to pass through the tissue at different angles

Looks at structure rather than function

Question 2

What do CT/CAT scans detect?

Answer 2

Detect brain disease
Tumor detection

Often done as one of the first tests in high risk trauma patients

Picks up loose bodies (piece of bone/ meniscus etc.)

Question 3

What color do bone, gases/liquids, and tissues appear on a CAT/CT scan?

Answer 3

Bone: white
Gas/liquid: Black
Tissue: Gray

Question 4

What are the cons of using CT/CAT scans?

Answer 4

1. More expensive
2. Better at soft tissue visualization but not the best
3. Greater radiation exposure

Question 5

What is a contraindication to using a CT scan?

Answer 5

Allergy to the contrast dye

Question 6

What is an MRI?

Answer 6

Magnetic field and radio frequency signals used to create cross section

Question 7

What does an MRI detect?

Answer 7

Detects edema, swelling, or water content in area

visualizes torn ligaments in wrist, ankle, knee

Question 8

What are the advantages to using MRI?

Answer 8

Does not use ionizing radiation
Contrast dye has low chance of side effects
Great contrast resolution for structural visualization

Question 9

What are the disadvantages to using MRI?

Answer 9

Claustrophobia
Weight and size of pt.
Noise 
keeping still
very expensive

Question 10

What is a contraindication to using an MRI?

Answer 10

Pace makers 
Aneurism clips 
Foreign bodies (metal)
Cochlear implants 
Large area tattoos 
Orthopedic hardware 
Pregnancy

Question 11

How do water and fat appear on a T1 weighted image?

Answer 11

Water and fluid containing tissues = DARK

Fat containing tissues = BRIGHT

Question 12

How do water and fat appear on a T2 weighted image?

Answer 12

Water and fluid containing tissues = BRIGHT

Fat containing tissues = DARK

Question 13

What is an fMRI (functional MRI)?

Answer 13

Displays metabolically active tissue, utilizes oxygen uptake as a measure of brain activity while a patient performs a task

Question 14

What are the 3 strengths of fMRI?

Answer 14

1. Non-invasive, replicable
2. Potentially good spatial localization
3. Common, well-validated technique

Question 15

What are 3 limitations of fMRI?

Answer 15

1. Mediocre temporal resolution (seconds)
2. Complex, highly variable data analyses
3. Expensive and time-consuming

Question 16

What is an electroencephalograph (EEG)?

Answer 16

Used to measure brain activity via the placement of electrodes on the head

Question 17

What does an EEG detect?

Answer 17

1. Detects electrical activity in brain
2. Key in diagnosing epilepsy: may help identify specific area for intervention:
   Lobectomy
   Cortical excision
   Hemispherectomy
3. Other uses: dx sleep disorders

Question 18

What is a PET scan?

Answer 18

Inject tracers, detects glucose metabolism, cancer, dementia, seizures, map brain function

Question 19

What are the strengths of PET scans?

Answer 19

1. uses a simple physiological mechanism
2. Provides absolute quantitative data
3. Allows imaging of anything that can be tagged

Question 20

What are the limitations of PET scans?

Answer 20

1. Poor temporal resolution
2. Poor spatial resolution
3. Requires injection of radioactive material