scans Flashcards
1
Q
CT
A
Computerised Axial Tomography
- > narrow beam x rays rotate around patient, passing through tissue at different angles
- > each beam attenuated according to density of tissue in its path
- > structures in brain
- > detect brain disease and monitor tissues over course of an illness
2
Q
MRI
A
Magnetic resonance imaging
- > magnetic field and radio waves
- > nuclei align with magnetic field, hydrogen atoms in the water of tissues are monitored
- > second magnetic field superimposed
- > direction changes, using energy from radio waves
- > radio waves switched off, nuclei return to original alignment & energy is released, detected, analysed & produces an image on screen
- > thin sections that are put together to make 3D images
- > diagnosis of tumours, strokes & injuries etc
3
Q
fMRI
A
functional magnetic resonance imaging
- > brain in action
- > follows oxygen uptake
- > deoxyhaemoglobin= absorbs radio wave, oxyhemoglobin = does not
- > less radio signal absorbed, higher the level of activity in that area
- > active areas = coloured = oxyhemoglobin present
4
Q
PET
A
positron emission tomography
- > detailed images, structure and function can be evaluated
- > isotopes with short half lives are incorporated into compounds ( ie. glucose) or molecules that bind to receptors.
- > labelled molecules = radiotracers
- as the radiotracer decays it emits positrons
- > when a tissue is active it will use more energy and there will be more blood flo, this will show up on the PET image as more radiotracers will be present in the area
- > when a positron collided with an electron, gamma rays are emitted and picked up by receptors
- > bright spots = high levels of neurone activity
5
Q
why are PETs only done 1x per year
A
safety & expensive
6
Q
what can cause alzheimer’s
A
as neurones die, beta amyloid protein, found in the mylin sheath clump together and form plaques that block signalling at synapses
- > accumulation of beta amyloid in the brain = sign of Alzheimer’s
- > PET can be used to assses the progression
