MRI Review
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Complete review of MRI
- 1.
- A.
Diamagnetic
- B.
Paramagnetic
- C.
Superparamagnetic
- D.
Ferromagnetic
- 2.Substances that exhibit a slight increase in the magnetic field when placed in an externally applied magnetic field. They have low and positive suseptibility.
- A.
Diamagnetic
- B.
Paramagnetic
- C.
Superpapmagnetic
- D.
Ferromagnetic
- 3.Gadilinium is an example of a _ substance
- A.
Diamagnetic
- B.
Paramagnetic
- C.
Superparamagnetic
- D.
Ferromagnetic
- 4.These substances exhibit positive suseptibility, but when placed in an external magnetic field they will remain magnetized when external magnetic field is removed
- A.
Diamagnetic
- B.
Paramagnetic
- C.
Superparamagnetic
- D.
Ferromagnetic
- 5.These substances exhibit positive suseptibility , are stronger than paramagnetic substances, but are weaker than ferromagnetic substances, and are used as T2 contrast agents
- A.
Diamagnetic
- B.
Paramagnetic
- C.
Superparamagnetic
- D.
Ferromagnetic
- 6.10000 gauss = _ Tesla
- A.
5000T
- B.
1 T
- C.
15000T
- D.
None
- 7.Magnets made of blocks or slabs or naturally occurring ferrous material.
- A.
Reistive
- B.
Permanent
- C.
Superconducting
- D.
Selenoid
- 8.Permanent magnets have field strengths of
- A.
0.5 - 1 T
- B.
0.06 -0.35T
- C.
1-3 T
- D.
Up to 10 T
- 9.Wires are aligned side by side to create magnet field
- A.
Permanent magnet
- B.
Resistive magnet
- C.
Selenoid magnet
- D.
Superconducting
- 10.This magnet can be used in horizontal or vertical field system, and have strengths up to 0.3 T, and can be turned off.
- 11.Magnets that utilize direct current applied to a coil of wire, and are submerged in liquid helium or cryogen to cool the wires.
- 12.The majority of superconducting magnets are __ in design and exhibit a (horizontal or vertical) magnetiic field.
- 13.Superconductive magnets are limited to _ T in clinical MRI by the FDA.
- 14.This type magnetic shielding uses metal, usually steel, in the scan room walls to contain the fringe field
- A.
Passive
- B.
Active
- 15.This type of magnetic shielding uses other magnets and their associated magnetic field to confine the field of the main magnet
- A.
Passive
- B.
Active
- 16.These coils utilize additional loops and circiutry to improve the efficiency with which the MR signal is induced in the coil, and increase SNR approximately 40% over the coil of the same size.
- A.
Quadrature
- B.
Vertical
- C.
Helmholtz pair
- D.
Phased array
- 17.Require the use of solenoid coils due to the orientation of the B0, more effiecient than linear coil, and can be combine with other coils electronically to improve signal uniformity through a region of interest.
- A.
Quadrature
- B.
Vertical
- C.
Helmholtz pair
- D.
Phased array
- 18.Allow for increased area of coverage without the reduction in SNR, have multiple coils and receivers.
- A.
Quadrature
- B.
Vertical
- C.
Helmholtz pair
- D.
Phase array
- 19.A narrow bandwidth allows for _slices
- A.
Thicker
- B.
Thinner
- 20.The slice location is determined by the
- A.
Phase gradient
- B.
Transmit frequency of the rf coil
- C.
Receiver frequency of the rf pulse
- D.
Transmit frequency of the rf pul
- 21.The receiver gandwidth represents the range of frequencies sampled during the
- A.
Phase gradient
- B.
Slice selection gradient
- C.
Frequency encoding gradient
- D.
Gradient coils
- 22.The receiver bandwidth is determined by the number of
- A.
Phase steps in the martrix
- B.
Frequency samples in the matrix
- 23.
- 24.The main purpose of the gradient subsystem is to
- A.
Select the slice plane
- B.
Select the imaging plance
- C.
Spatially encode the MR signal
- D.
All of the above
- 25.This gradient coil varies the intensity of the magnetic field in the head to foot direction
- A.
X
- B.
Y
- C.
Z
- 26.This gradient coil varies the intensity of the magnetic field in the right to left direction
- A.
X
- B.
Y
- C.
Z
- 27.A way to express the gradient performance referring to the acceleration of the gradient magnetic field to its maximum amplitude, expressed in units of T/m/s.
- A.
Rise time
- B.
Coil configuration
- C.
Slew rate
- 28.The gyromagnetic ratio of h+ in 1 T is
- 29.THE SIGNAL INDUCED IN A RECEIVER COIL IMMEDIATELY FOLLOWING AN RF EXCITATION PULSE IS KNOWN AS THE
- 30.THE FID CAN BE ALTERED BY
- 31.THE DIFFERENCE IN PRECESSIONAL FREQUENCY OF THE HYDROGEN IN FAT AND WATER IS KNOWN AS
- A.
FOURIER TRANSFORM
- B.
FID
- C.
SPIN DENSITY
- D.
CHEMICAL SHIFT
- 32.THE CHEMICAL SHIFT BETWEEN FAT AND WATER AT 1.5 T IS __, OR H + WATER WILL PRECESS THIS MUCH FASTER THAN THE H+ IN FAT
- 33.THE DIFFERENCE IN PRECESSIONAL FREQUENCY, DUE TO THE CHEMICAL/MOLECULAR ENVIRONMENT, IS KNOWN AS
- 34.TO EVALUATE IMAGES WITH T2* CONTRAST _ IMAGES ARE REQUIRED
- 35.WHEN IS THE SLICE SELECTION GRADIENT APPLIED
- A.
DURING THE ECHO
- B.
DURING THE 90 DEGREE RF PULSE
- C.
AFTER THE 180 DEGREE RF PULSE
- D.
DURING THE 90 AND 180 DEGREE RF PULSE
- 36.SLICE THICKNESS IS DETERMINED BY THESE 2 THINGS
- 37.THE PHASE ENCODING GRADIENT REPRESENTS
- A.
THE AMOUNT OF TIMES THE ECHO IS SAMPLED
- B.
THE LINE IN K SPACE ON WHICH THE DATA WILL BE PLOTTED DURING THE READOUT PERIOD
- C.
THE AMOUNT OF RESOLUTION IN THE IMAGE
- 38.WHEN DOES PHASE ENCODING TAKE PLACE
- 39.THE MIDDLE LINES OF K SPACE CONTAIN OVER 90% OF THE
- 40.THE OUTER LINES OF K SPACE HOLD
- 41.
- A.
A LOWER AMPLITUDE OF THE Y GRADIENT IS SELECTED
- B.
A HIGHER AMPLITUDE OF THE Z GRADIENT IS SELECTED
- C.
A HIGHER AMPLITUDE OF THE X GRADIENT IS SELECTED
- D.
A LOWER AMPLITUDE OF THE Z GRADIENT IS SELECTED
- 42.THE ONLY WAY THE SPATIAL RESOLUTION CAN INCREASED IS TO
- A.
INCREASE THE FOV
- B.
DECREASE THE PHASE ENCODINGS OF THE MATRIX
- C.
INCREASE THE VOXEL VOLUME
- D.
REDUCE THE VOXEL VOLUME
- 43.RF SHIELDING IS KNOWN AS A
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