Week 6 TBI + vascular

Question 1

Ultrasound

Answer 1

Used to imagne brains in newborns/babies.
Fontanelle are transparent to sound waves.

Used:
Suspected meningitis, perinatal ischaemia, hydrocephalus, haemorrhage.

Question 2

X-Ray

Answer 2

Best for bone.

Used: skull fractures, haemorrhage.

Question 3

Computerized Tomography (CT)

Answer 3

Uses X-rays.
Slices through the head, good for spatial resolution.

Not good for brain.

Used: structures associated with the brain (ie. oedema, bone fractures).

Question 4

Magnetic Resonance Imaging (MRI)

Answer 4

1. Forces protons to align with the magnetic field (T1).
2. Protons are not completely aligned so they spin - called Precession.
3. Electromagnetic Radio Frequency (RF) is applied at the precession freq, causing protons to absorb energy and change their alignment with respect to T2 (RF applied at 90 degrees).
4. RF pulse is removed and the energy is retransmitted, causing protons to relax back to external field (T1).

T1 weighted enhances fat. T2 enhances water.

Image generated because time it takes for proton to realign is dependent on the tissue (takes longer to realign in water vs fat).

Question 5

Positron Emission Tomography (PET)

Answer 5

Uses radioactive isotope of glucose which is injected, brain and tumours uses lots of glucose.

Cyclotron to generate isotopes.

Radiolabelled fluoro-deoxyglucose (F-FDG).

Question 6

Stroke

Answer 6

An acute brain injury/dysfunction resulting from pathological process of blood vessels.

Question 7

Stroke Subtypes

Answer 7

1. Ischaemic: 80-85%
2. Intracerebral haemorrhage: 10-20% but accounts for 50% of stroke disability/mortality.

1. Thrombosis or embolism due to atherosclerosis.

Question 8

Virchows Triad

Answer 8

1. Endothelial dysfunction.
2. Haemodynamic changes.
3. Hypercoagulability.