Neuro Imaging Flashcards
What is a CAT/CT scan?
Uses thousands of xray beams to pass through the tissue at different angles
Looks at structure rather than function
What do CT/CAT scans detect?
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.)
What color do bone, gases/liquids, and tissues appear on a CAT/CT scan?
Bone: white
Gas/liquid: Black
Tissue: Gray
What are the cons of using CT/CAT scans?
- More expensive
- Better at soft tissue visualization but not the best
- Greater radiation exposure
What is a contraindication to using a CT scan?
Allergy to the contrast dye
What is an MRI?
Magnetic field and radio frequency signals used to create cross section
What does an MRI detect?
Detects edema, swelling, or water content in area
visualizes torn ligaments in wrist, ankle, knee
What are the advantages to using MRI?
Does not use ionizing radiation
Contrast dye has low chance of side effects
Great contrast resolution for structural visualization
What are the disadvantages to using MRI?
Claustrophobia Weight and size of pt. Noise keeping still very expensive
What is a contraindication to using an MRI?
Pace makers Aneurism clips Foreign bodies (metal) Cochlear implants Large area tattoos Orthopedic hardware Pregnancy
How do water and fat appear on a T1 weighted image?
Water and fluid containing tissues = DARK
Fat containing tissues = BRIGHT
How do water and fat appear on a T2 weighted image?
Water and fluid containing tissues = BRIGHT
Fat containing tissues = DARK
What is an fMRI (functional MRI)?
Displays metabolically active tissue, utilizes oxygen uptake as a measure of brain activity while a patient performs a task
What are the 3 strengths of fMRI?
- Non-invasive, replicable
- Potentially good spatial localization
- Common, well-validated technique
What are 3 limitations of fMRI?
- Mediocre temporal resolution (seconds)
- Complex, highly variable data analyses
- Expensive and time-consuming
What is an electroencephalograph (EEG)?
Used to measure brain activity via the placement of electrodes on the head
What does an EEG detect?
- Detects electrical activity in brain
- Key in diagnosing epilepsy: may help identify specific area for intervention:
Lobectomy
Cortical excision
Hemispherectomy - Other uses: dx sleep disorders
What is a PET scan?
Inject tracers, detects glucose metabolism, cancer, dementia, seizures, map brain function
What are the strengths of PET scans?
- uses a simple physiological mechanism
- Provides absolute quantitative data
- Allows imaging of anything that can be tagged
What are the limitations of PET scans?
- Poor temporal resolution
- Poor spatial resolution
- Requires injection of radioactive material
