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What are the two types of brain imaging techniques? What are they used for? Give examples.
What are electrophysiologic studies used for? Give examples.
- 1. Structural: To look at shape of brain for abnormalities or if damage is present; dx of strokes, tumors, AVM); cerebral angiography, CT/CAT, MRI
- 2. Functional: To look at brain activity and see if part of brain is still working; what parts of the brain are used for certain tasks; certain parts of the brain when active: utilizing O2 and blood flow; examines blood flow for examining parts of the brain that are active during a task; PET, SPECT, fMRI
To look at the duration and sequence of activity in the brain; EEG, MEG, ERP, EMG
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Cerebral Angiography
Invasive or noninvasive?
What is it used for?
How does it work?
- Invasive
- Looks at the shape of the artery; uses X-ray to view the picture
- A radiopaque substance is injected into artery/vein that absorbs x-rays less or more than surrounding tissue
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Computed axial tomography (CAT/CT)
Uses x-ray beams, which are affected by the ___ of the tissue through which it passes, to produce _____.
Brain lesions such as ___, ___, ___, are visible as areas of high-density, appears ___, or low-density, appear ___.
Lesions associated with hemorrhage or aneurysm shows as an area of ___-density.
An infarct/swelling shows as an area of __-density.
Blood & bone are ___-density; tissues are __-density
- density, image of the brain
- CVA, TBI, tumor
- white; dark
- high, low
- high, low
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Magnetic Resonance Imaging (MRI)
Constructed from measurement of waves that ___ atoms emit when activated within a magnetic field.
Reveals differences in ___ content between different tissues.
Pathologic areas (CVA, TBI, tumors, myelination) are __, or increase in signal intensity.
- hydrogen
- water
- bright
- *Bone contains little water, few signals=less visible
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Functional Magnetic Resonance Imaging (fMRI)
Provides images of brain __ and __.
Function imaged by detecting changes in local blood __, __, and __ saturation.
Advantages
Invasive or noninvasive?
Radiation risk?
How is the image quality?
Used primarily in clinic or research?
- Structure and function
- volume, flow, oxygen
- noninvasive, low risk, superior
- research
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Electroencephalography
measures duration and sequence of ___ ___ in the brain.
What is it used to diagnose?
Used in research or clinically?
Disadvantage?
- electrical activity
- seizures, tumors, head injuries, degenerative diseases, brain death
- Both
- only measures activity in cortex, not deeper
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Evoked potentials (ERP)
Measures electrical activity in response to a __, __, or __ stimulus.
Multiple responses are averaged and the data are called __-__ or ___ ___.
- auditory, visual, somatosensory
- event-related, evoked potential
- *Measures how long an activity occurred
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Electromyography
Measures electrical activity during ___.
What is examined to diagnose nerve or muscle diseases?
- Movement
- Quality, speed, magnitude of electrical impulses
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