________ is the magnet by itself, and the magnet is always on.
New cards
2
RF cage
________ has to be in the MRI room to absorb any signals from outside, otherwise FM radio frequencies would be measured.
New cards
3
T2
________ is the transvese relaxation time (spin minus spin relaxation)
New cards
4
Z directional coils
________ are called Maxwell pairs.
New cards
5
NMR
________ is nuclear magnetic resonance, but is not related to radioactive decay (the nucleus is spinning, but theres no radioactivity)
New cards
6
Resonance
________ comes from B1 (the additional force) being at the same frequency as B0 (𝜔0) to make sure there is maximum energy being delivery.
New cards
7
Protons
________ and neutrons are spinning inside the atom, which act like magnets.
New cards
8
Larmor frequency
________ depends only on the material (𝛾) and the main magnetic field strength (B0)
New cards
9
vector 𝜇
The ________ precesses (spins) around the z axis st an angular frequency 𝜔 (radians per second)
New cards
10
M
As ________ returns to equilibrium, an RF signal is produced by energy releasing from the absorbed energy that was given to the material from B1.
New cards
11
Relaxation
________: The process by which M returns to steady state configuration after a B1 is done being applied.
New cards
12
𝜔0
While oscilating at ________, the RF pulse can have three shapes, rectangular, sinc, and triangular.
New cards
13
angular momentum
Spinning nuclei possess ________ (J) called spin.
New cards
14
Α
________ (always in radians) is the integration from 0 to 𝜏 over B1 (t) with respect to t (in seconds)
New cards
15
Gradients
________ are localized in x, y, and z directions.
New cards
16
TR
________ is the repetition time.
New cards
17
max
For the ________ transverse component Mxy, α is set to pi /2 radians.
New cards
18
MRI
________ offers images of the same object in different contrasts to bring attention to different areas.
New cards
19
B1
Since the spins and ________ field are both rotating, you can image from a spinning reference.
New cards
20
z axis
If M tips away from the ________ (during excitation), a component in the x- y plane is generated.
New cards
21
coil
The ________ with current running through it acts as the magnet, and is surrounded by liquid Helium to keep the ________ cool (decreasing resistance and energy lost to heat)
New cards
22
Mz^0
________ is the steady state of Mz.
New cards
23
Mxy
________ decays at a faster rate (T2* instead of T2) because of signal desync.
New cards
24
TE
________ is the echo time.
New cards
25
X directional coils
________ are called Golay coils.
New cards
26
Y directional coils
________ are called Golay- type coils.
New cards
27
signal component
The ________ is always in the transverse x- y plane.
New cards
28
signal intensity
The difference in ________ is used to discriminate different tissues by representing them as brightness.
New cards
29
MR signal
________ is always recorded in the xy plane.
New cards
30
gyromagnetic ratio
The ________ can also be gamma divided by 2pi.
New cards
31
nuclei
If a(n) ________ has an even atomic number, the magnetic fields cancel out.
New cards
32
transverse plane
The ________ (xy) is rotating at 𝜔, which is equal to 𝜔0, so it can be considered a rotating plane (x- y)
New cards
33
K
________ is the scaling factor.
New cards
34
equilibrium
At ________, the net magnetization vector M precesses about the z- axis.
New cards
35
Mz
________ (0+) is transverse magnetization Mxy immediately after the RF pulse.
New cards
36
longitudinal Mz
The ________ and transverse Mxy components vary as time changes, and are descibed by Bloch Equations.
New cards
37
Hydrogen
________ has the highest gyromagnetic ratio.
New cards
38
15T magnet
A(n) ________ is about 30, 000 times stronger than Earths magnetic field.
New cards
39
Spin echo
________ makes the slower spins catch up with faster oens to sync the signal.
New cards
40
rectangular pulse
For a(n) ________ after 𝜏 seconds, the vector M has rotated at an angle α.
New cards
41
T2 weighting
________: We want ta long TR (minimize T1 differences) and an intermediate TE.
New cards
42
external magnetic field
The net (bulk) magnetization vector with a(n) ________ is nonzero.
New cards
43
Larmor Frequency
The angular frequency at which the bulk magnetization factor precesses around the z-axis
New cards
44
Relaxation
The process by which M returns to steady state configuration after a B1 is done being applied
New cards
45
Pulse sequence
Carefully timed set of scanner operations used to generate images
New cards
46
Proton density weighting
We want a long TR and a short TE
New cards
47
T1 weighting
We want an intermediate TR and a short TE (becomes a constant scaling factor, less noise)
New cards
48
T2 weighting
We want ta long TR (minimize T1 differences) and an intermediate TE
Studied by 2 people
Note 
Flashcard (30)