Interpretting Scans Flashcards
What type of scan is easier for agitated patients?
CT
CT scan is equal to approx how many Chest X-rays?
100
On a CT scan, the right side of the brain image =
Left side of the actual brain
On a CT scan, increased density is what colour ?
Whiter (more absorption of X-rays)
On a CT scan, decreased density is what colour?
Blacker (less absorption of X-rays)
How do contrast agents work?
They leak into brain tissue when the blood brain barrier is disrupted by a disease process
List the type of hyper dense (i.e. whiter) lesions on a CT
Acute haemorrhage
Contrast enhancement
Metal - injury/surgery
What type of isodense lesion is there?
Subacute haemorrhage
What types of hypodense (Blacker looking) lesions are there?
Infarction
Oedema
Tumour
Abscess
How does MRIs work?
By measuring the energy emitted by protein particles within water molecules when exposed to strong magnetic fields
Why might someone not be able to have an MRI
If they have metal in their body
If they have an implanted electronic medical device
If they can’t stay still for any reason
What are the advantages of an MRI
Several different planes (as opposed to 2)
Slices are thinner (therefore more images)
Spatial resolution is better than CT (more detail is visible)
Before looking at the images of the brain, how should you read the scan?
- Patients name and date of scan
- Modality (CT vs MRI)
- Constraint vs non-contrast
- Scan quality
How to read a scan with respect to the brain?
- Brain size compared to CSF (evidence of atrophy)
- Compare left and right sides for symmetry
- Look at the edge of brain (want the sulci to be visible - otherwise indicates swelling)
- Is the border between grey and white matter clear?
- Position of falx cerebri (should be midline)
- Any hyper/hypo dense regions
- Any contrast enhancement if contract scan
