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36 Cards in this Set
- Front
- Back
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y = kx + c is an example of a:
a. Linear equation b. quadratic function c. trigonometric function d. exponential function |
a. linear function
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What is the circle circumference in radians?
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2pi R
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Fourier Transform is a mathmatical technique that converts ___ domain data into frequency domain data.
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Time
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Fourier Transform is a mathematical technique that converts time domain data to ____ domain data.
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Frequency.
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Fourier transform constructs a diagram which displays amplitude and ___ of each sinusoid.
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frequency.
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What year was FFT implemented into computer processing?
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1965 by W.Cooley and J.Tukey
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What is the magnetic susceptibility in a vacuum?
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0
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What is the equation for Faraday's law?
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V = -dB/dt
V= induced voltage dB = a change of magnetic field -dt = the time taken for that change |
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A ____ magnet would create a static magnet.
a. DC b. AC |
DC
- AC electrical currnet in a coil results in an oscillating magnetic field. This creates magnetic radiation. This also creates an "antenna effect" (acts as a transmitter and a receiver) |
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What is the equation for Ohm's law?
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V=IR
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A magnetic field is created by __
a. a stationary electric field b. a moving electric charge c. a rotating electrical field d. none of the above e. b and c |
e. b and c
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Magnetic induction causes a current in a loop of wire that causes a magnetic field to ___
a. add to the source magnetic field b. oppose the source magnetic field |
b. oppose the source magnetic field
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Electromagnetic radiation consists of magnetic and electric fields that ___
a. rise and fall in synch with each other b. are always oriented parallel to each other c. reach maximum absolute values at different times d. are always oriented perpendicular to each other e. a and b f. c and d g. b and d |
f. c and d
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Two sine waves with the same frequency which are 180 degrees out of phase will ___
a. sometimes add constructively and sometimes deconstructively b. will never add constructively c. cannot be added together at all |
b.
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A single proton exhibits the property of __.
a. spin b. electric charge c. mass d. magnetism e. all of the above |
e. all of the above
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As the magnetic field increases ___
a. M0 gets smaller b. M0 gets bigger c. the energy difference between two allowable proton spin energy levels increases |
b and c
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In the rotating frame of reference, when an RF pulse is applied at the resonance frequency, M0 will spiral down towards the XY plane ___
a. true b. false |
b. false
After an RF pulse is applied, M0 wants to return to equilibrium, so it starts to recover longitudinal magnetization. |
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In the rotating frame of reference ___
a. B1 field appears stationary b. B0 field appears vanishing c. B0 is always much larger than B1 |
A and B.
B0 = the NMV B1 = RF |
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B0 represents ____
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the NMV
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B1 represents ___
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the RF
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Which of these relations are always true
a. T2 < T1 b. T2* < T2 c. T1 < T2 < T2* |
c
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T2 decay is caused by ___
a. spin-spin interactions b. imperfections in the magnetic field c. photons being emitted d. magnetic susceptibiliy |
a. spin spin interactions
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T1 and T2 tissue values are usually ___
a. higher a high field strengths b. lower at high field strengths |
a. The T1 and T2 relaxation times of a tissue are dependent on the strength of the magnet. As field strength increases, tissues take longer to relax.
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Reversing the effects of static field inhomogeneities of B0 is the concept behind ___
a. GRE sequences b. SE sequences c. GRE and SE sequences |
b. Spin Echo sequences
The spin echo rephases the spins, so when t=2tau, you are left with the effects of T2, not T2* |
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True or False - Fourier Transform converts time domain data into frequency domain data.
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True
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True or False - A rotating vector creates a signal wave along the x and y axis.
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False. It creates TWO waves along the xy axis.
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True or False - In the quantum physics model - spins have preference as to where they exist - parallel vs anti-parallel.
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True
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The Bolzman distribution states that for every 2 million protons there are _______ more protons at the lower energy level than at the higher energy level.
A. 9 B. 90 C. 900 D. 9,000 E. 90,000 |
A. 9
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Avogadro's number discusses molecules per mole. In the example given: voxel = 2mm x 2mm x 5mm - how many excess protons were there?
A. 6 B. 90,000 C. 9 million D. 6 million billion E. 90 million billion |
D. 6 million billion
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Which of the following are true statements concerning T1?
A. when 63% of spins have returned to B0 B. it is a spin-lattice energy exchange C. large molecules have a long T1 D. all of the above E. A and B only |
E. A and B only
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MEMORIZE:
T1 (spin-lattice) relaxation time: Starting from zero magnetization in the Z direction, Mz magnetization will return to 63% of it's maximum value M0 in a time T1. |
MEMORIZE:
T1 (spin-lattice) relaxation time: Starting from zero magnetization in the Z direction, Mz magnetization will return to 63% of it's maximum value M0 in a time T1. |
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T/F:
large molecules have short T1 times |
False. Large molecules have long T1 times. Small molecules are tumbling too rapidly, so they have a longer T1 time.
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Which of the following statements are true concerning T2 recovery?
A. there is no energy exchange - only phase changes B. it is a spin-spin interaction C. magnetization has decayed to 37% of original value D. all of the above E. B and C only |
A. there's no energy exchange.. it's a change of phase only... Mxy dephasing
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MEMORIZE
The _____ determines the pixel value in an image a. signal strength b. signal difference |
The signal strength determines the pixel value in an image.
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The ___ determines the contrast in an image
a. signal difference b. signal strength |
The signal difference determines contrast in an image.
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What are the two sources of B0 inhomogeneity?
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Magnetic field B0 imperfections and human tissue susceptibility differences.
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