Neuroimaging Flashcards
1
Q
How does conventional radiography work?
A
- as x-rays travel through head, they are absorbed to different degrees
- dense tissue absorbs most appearing white
2
Q
How does pneumoencephalography work?
A
- same as conventional x-rays except CSF taken out of spinal cord and replaced with air
- the air moves up and fills the ventricles to get a clear image of them
- cons: painful and invasive
3
Q
How does angiographies work?
A
- same technology as x-rays except substance that absorbs x-rays is injected into the blood stream to view circulatory abnormalities
- cons: dangerous, painful
4
Q
How does a computerized transaxial tomography (CT scan) work?
A
- passing a narrow x-ray through the same object at different angles to create a 3D image
- useful for localizing tumors and lesions
- quick, static and inexpensive
- not ideal for children/people who cannot stay still
5
Q
How does magnetic resonance imaging work?
A
- a large magnet and specific radiofrequency pulse generate brain signal
- magnet aligns hydrogen atoms
- expensive but none invasive and safe to repeat
6
Q
How does magnetic resonance spectroscopy work?
A
- varies radiofrequencies to image concentrations of remaining brain material
- to distinguish brain cells from other substances
- useful for degenerative diseases. demyelinating diseases and abnormalities in brain metabolism
7
Q
What is T1 more useful for?
A
- volumetric measurement
8
Q
What is T2 more useful for?
A
- detecting lesions (more contrast, ventricles appear white)
9
Q
What is FLAIR useful for?
A
- detection of infarction, multiple sclerosis
10
Q
How does diffusion tensor imaging work?
A
- MRI method that detects directional movements of water molecules
- used to map pathways and connectivity
11
Q
How does positron emission tomography work?
A
- to study metabolic activity in brain cells engaged in processing functions
- water with radioactive molecules are injected into the blood stream and the PET scanner detects the radiation
- image represents areas of high and low blood flow
- to study cognitive function through glucose and oxygen metabolism
- expensive
12
Q
How does fMRI work?
A
- as neurons become more active, they use more oxygen resulting in a dip in the blood, blood flow increased and oxygen exceeded
- unoxygenated blood magnetic properties are higher
- to measure which areas are active during a task
13
Q
How do electroencephalography (EEG) work?
A
- measures voltage fluctuations or brain waves
- electrodes placed on head and difference between them used to determine electrical activity
14
Q
What are the pros and cons of EEG?
A
- pros: temporal resolution high, relatively inexpensive
- cons: spatial resolution is low
15
Q
What is EEG used for?
A
- electrical activity related to consciousness
