MRI Flashcards
….. act as a good MR nucleus
Hydrogen (1H,H+)
What does MRI utelize?
Hydrogen[protons] magnetic spin parallel to each other and present on radio-frequency pulses to produce image
Why are hydrogen atoms used in MRI?
Bcz they have a magnetic spin
When are atoms able to spin around themselves[unstable] ?
An atom that has an odd number of proton or neutron
When do you get signals from the protons to form an image?
The time it takes from excitation to relaxation time
which is called RELAXATION TIME
*How can you differentiate different tissues from each other?
Based on their different relaxation times they generate different image contrasts
When are protons spin vectors align perpendicular?
When an RF pulse is activated
when do protons go back to parallel alignment[aka in magnetic field]?
When RF [RADIOFREQUENCY] is disabled
Why do adipose[fat] tissue appear to have a brighter image than CSF?
Bcz fat tissue require less time to reach relaxation time due to the low density of fat and thus low signals received.
UNLIKE, in CSF[water] or bone are dense enough to appear dark due to the high signals received & the longer it takes for the protons to reach relaxation time
What is the magnet system formed from?
Superconductive coils
What is the most imp job of the coils?
Coils transmit several types of waves , the most imp is :Radio-frequency RF pulse to excite the protons
&
Then get the signals to the relaxed state
***what is the job of the radio-frequency coils(Transceiver)?
They transmit RF pulses to excite the protons and receive signals when the atoms relax
Which type of magnet is kept in a cold helium and nitrogen casing ?
Superconductive magnet
**which part of the MRI acts as both a transmitter and receiver?
The 2. Part of the MRI which is RF coils (Transceiver) ; THEY SEND RF PULSES TO EXCITE THE PROTONS
AND
RECEIVE THE SIGNALS WHEN THE PROTONS ARE RELAXING
**What are the 2 most imp electrical components of the MRI?
superconductive magnet & RF coils
