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Name 2 types:
what does each type determine?
- Structural Imaging techniques (cerebral angiography, CT/CAT, MRI)
- Functional imaging techniques (Pet, SPECT, fMRI)
- Structural imaging: looks at shape of brain to determine abnormalities or damages present (good for stroke, tumors, AVMs, etc)
- Functional imaging: looks at activity of the brain and the parts that accomplish specific tasks. Activity is determined by measuring increases in O2 consumption, blood volume, and blood flow
Name 4 examples:
What does it determine?
- EEG, MEG, ERP, EMG
- determines duration and sequence of activity in the brain during tasks
What does it use?
What does it create?
is it invasive?
What does it allow you to see?
- picture called angiogram
- yes, because you must inject the patient with radiopaque contrastive dye
- the shape of the artery (you can see AVMs, clots, etc)
Computed Axial Tomography
What does it use and how?
What absorbs the rays?
- Uses x-ray beams, which are changed by the density of different tissues, this creates an image
- Different tissue densities appear as different colors, the denser the tissue, the lighter the image (bone shows as white)
Magnetic Resonance Imaging (MRI)
What is it constructed from?
What does it reveal differences in?
what shows "brighter"?
- Uses magnetic field and radio waves to construct a picture that is sensitive to hydrogen atom wave emittance
- reveals differences in water content between different tissues
- pathologic areas (tumor, infarcts, etc)
- This diagnostic tool shows great detail.
Functional Magnetic Resonance Imaging (fMRI)
What does it provide an image of?
What does it detect?
Is it invasive?
What is it mostly used for?
- Images of brain activity and structure
- changes in local blood volume, flow, and oxygen saturation
- no, there is no radiation risk, and very high quality images
- it is mostly used for research because finding lesions consistently across clients is difficult to attain.
What does it measure?
what is it used to diagnose?
- Activity while performing task, duration, and sequence of electrical activity in the brain
- seizure disorders, tumors, head injuries, degenerative diseases, brain death
Evoked Potentials (ERP)
What does it measure?
How does the test function?
- Electrical activity in response to a visual, somatosensory or auditory stimulus
- Multiple responses are averaged and the data are called event-related or ended potentials
What does in measure?
What is examined?
- Measures electrical activity of the muscles during movement
- Quality, speed, and magnitude of electrical impulses, this helps to determine nerve or muscle diseases