Brain Scans Flashcards
What is PET scan used to look at?
Brain activity
What is a fMRI scan used to look at?
Brain structure and function
What is a CAT scan used to look at?
Brain structure
What is the method to using a PET scan?
-Inject with a radioactive chemical.
-Radioactivity is picked up by scan.
How is activity shown in a PET scan?
-More active sites are warmer/darker colors.
-Less active sites are cooler/lighter colours.
-Activity is shown by how much glucose and area used(more active needs more glucose).
What are the strengths of a PET scan?
-Ethical as they are not invasive as surgery would be.
-Very reliable and can be repeated.
-Valid as they measure what they set out to measure.
-Can look at receptors of neurotransmitters unlike an fMRI.
What are the weaknesses of a PET scan?
-Radioactive tracer is invasive.
-Had to pinpoint areas of the brain as the imaging is broad.
-More expensive than a CAT scan.
What is an fMRI machine and how does it work?
-A large cylinder where the person must lie completely still.
-Sends magnetic and radio waves through the body.
How does an FMRI measure brain function?
-As brain activity increases it needs more oxygen which is carried to the brain via red blood cells.
-If the red blood cells are full it repels the magnetic field, but if empty it attracts the magnetic field creating an image of the brain.
How does an fMRI measure brain structure?
-Hydrogen atoms move towards the magnetic field and we measure when they move back.
-Computer tells us where areas of the brain are.
What are the strengths of a fMRI scan?
-Valid as the scan is real.
-They are scientific, replicable and repeatable (reliable).
-Very precise in its measurement of the blood flow in the brain.
What are the weaknesses of a fMRI scan?
-Not completely ethical as the cylinder can be uncomfortable.
-Cannot measure NT like PET scan.
-Can effect the blood flow in the brain.
-Certain people cannot use the machine (those with pacemakers).
-Can only give limited information.
How is a CAT scan used to look at brain structure?
-An x-ray beam is beamed into the brain at multiple angles to produce a full picture,
-Can spot damages and tumours.
What are the strengths of a CAT scan?
-Non-invasive
-They are scientific, replicate and repeatable (reliable).
-Modern techniques allow for different angles so less overlap effecting the scan.
-Helps surgeons before starting surgery.
-Can give a 3d representation of the brain.
What are the weaknesses of CAT scans?
-Possible dangers from radiation.
-Not as helpful as an MRI scan for looking at infection.
-Image is easily changed by head movement.
