⭐ • Research Methods: Brain Scanning Flashcards
What are the 4 types of brain scanning techniques?
- MRI scan
- fMRI scan
- PET scan
- CAT/ CT scan
What does ‘CAT’/ CT stand for?
Computer
Assisted
Tomography
Scan
Describe the process of a CAT/ CT scan
- Removal of metals as will disrupt scan
- Lie on scanner table and keep still for entire 30 min procedure
- Series of X-ray beams passed through head via rotating
- Creates cross-sectional images of brain
- MAY require injection of dye to make blood vessels more clear
What are CAT/ CT scans used for?
- Looking for lesions/ structural damage or imperfections
- Looking for tumours
What are the advantages to a CAT/ CT scan?
- Painless, noninvasive, and accurate.
- Images bone, soft tissue, and blood vessels all at the same time
- Provides very detailed structural imaging
What are the disadvantages to a CAT/ CT scan?
- Radiation exposure due to x-ray beams - exposure to ionizing radiation
- Possible reactions to the contrast agent/ dye
What does ‘PET’ stand for?
Positron
Emission
Tomography
Scan
Describe the process of a PET scan
- Radioactive tracer injected
- Oxygen & glucose accumulate in brain areas that are metabolically active
- As glucosed used radioactive tracer breaks down releasing** neutron & positron**
- Upon positron hitting electron both are destryed and 2 gamma rays are released
- Gamma ray detectors record areas in which rays are emitted & image produced of activity
What to the colours represent in terms of brain activity in a PET scan?
- RED/YELLOW = high activity/ metabolic rate
- BLUE/GREEN = low activity/ metabolic rate
What are PET scans used for?
- Showcasing brain activity/ neurotransmission
- Highlighting what areas of the brain are in use/ not in use etc
What are the advantages to a PET scan?
- Valid as scan measures what it claims to measure
- Reliable as it can be repeated and same results will be found
What are the disadvantages to a PET scan?
- Radioactive tracer is invasive, can raise ethical concerns e.g. if participant can have injection safely
- Scan is claustraphobic & must be carefully explained to participant
- Expensive
- Subjective as images arent always very clear/ colours distinguishable
What does ‘MRI’ stand for?
Magnetic
Resonance
Imaging
Scan
Describe the process of an MRI scan
- Whole body in tube with noisy machine
- Person has to keep still
- Dye - contrast medium - injected to help highlight relevant areas
- Uses detection of radio frequency signals produced by displaced radiowaves in magnetic field
What are MRI scans used for?
- Identification of tumours/ lesions
- Structural
What are the advantages to an MRI scan?
- no x-rays or radioactive material used
- provides detailed view of brain
- Pretty non-invasive apart from dye
- Valid as scan results often link with what is found in reality
- Reliability due to replicability, negating subjectivity as inter-rater
What are the disadvantages to an MRI scan?
- Scan can be very stressful due to loud noise and claustraphobic setting
- Stress should be taken into consideration with patient and medical history to understand if they would react negatively
- Only provides clear images of soft tissues, not brain actitvity
- Possible reactions to the contrast agent/ dye
What does ‘fMRI’ stand for?
functional
Magnetic
Resonance
Imaging
Scan
Describe the process of an fMRI scan
- Participants’ head placed into brace to hold it still
- Loud noise and have to remain still entire time
- Works by detecting changes in oxygenation in brain e.g. more/ less blood in response to neural activity (neurons & their signals)
- When brain area more active it consumes more oxygen and to meet increased demand blood flow increases to the active area
- fMRI detects change in bloodflow to display image of brain activity
- Contrast medium e.g. dye can be used
What are fMRI scans used for?
- Highlighting what areas of the brain are in use/ not in use etc
What are the advantages to an fMRI scan?
- No risk of radiaion exposure unllike CAT or PET
- High resolution so very clear images
- Can record signals from all areas of brain not just surface cortexs’, can record signals from deep in brain
What are the disadvantages to an fMRI scan?
- Dispute over if it actualy measures what it claims as increased blood/ oxygen could be in preparation for neural activity, not because of it
- Very noisy therefore unpleasant
- Images produced extremely subjective and must be interpreted carefully as correlation doesnt imply causation
- Possible reactions to the contrast agent/ dye
Out of the 4 scanning techniques, what ones are invasive + give reasoning
- MRI scan - slightly invasive = due to dye injection for contrast medium
- fMRI scan - slightly invasive = due to dye injection for contrast medium
- PET scan - invasive = due to radioactive tracer injection
- CAT/ CT scan - slightly invasive = due to dye injection for contrast medium
Out of the 4 scanning techniques, what ones scan for brain activity?
- fMRI scan
- PET scan
Out of the 4 scanning techniques, what ones scan for brain structure?
- MRI scan
- CAT/ CT scan
- Out of the scanning techniques, what ones require interpretation and are therefore subjective?
- fMRI scan
- PET scan
Both scanning techniques that monitor activity require interpretation due to colours etc…
- Out of the scanning techniques, what ones do not require interpretation and are therefore objective?
- MRI scan
- CAT/ CT scan
What does validity refer to in relation to brain scanning?
If what is being measured is actually correlated to what is being said/ what is happening in reality
Out of the 4 brain scanning techniques, what ones have strong reliability?
- ALL of the scanning techniques have a strength of reliability due to the inherent ability (due to the nature of scanning techniques) for the tests to be repeated consistently and for multiple researchers to observe the results, therfore allowing for inter-rater reliability
