Magnetic Resonance Imaging (MRI) Flashcards
A moving electric field will set up a magnetic field around it
electro-magnetic induction
Charged subatomic particles (i.e. protons) will have a spin or wobble which create a
magnetic dipole moment
A magnetic field can cause a change in the direction of ___________.
the spin of hydrogen nuclei
Relaxation of the hydrogen molecules upon turning off magnetic fields will produce _______.
RF waves
the time that it takes the nuclei to recover from longitudinal magnetism
T1
the time that it takes to recover from transverse magnetization
T2
__________ are given off are recorded and analyzed by a computer to produce MR image
RF signals
A circular main magnet produces a strong homogeneous field of _______Tesla with super-conducting coils, cooled with liquid helium
.5 -3 Tesla
___ sets of gradient coils installed inside the bore of the main magnet produce magnetic field gradients in 3 dimensions (x, y and z, which is in the direction of the main magnet)
3
it improves the visibility of inflammation, tumors, blood vessels and, for some organs, blood supply.
Gadolinium contrast
weighted images display the tumor and edema as a low signal or dark area
T1
weighted images display the tumor and edema as a high signal or bright area
T2, T2 = H2O (water (ie. eyes) shows up bright in these datasets)
locations with large amounts of free water, produce a ____ signal, whereas bone emits a very ____ signal.
strong, weak
Different _____ create images with different contrast that are useful for viewing different anatomy.
pulse sequences
higher field strength =
larger field of view (FOV) =
greater distance from center =
increased geometric distortion
