In the absence of a magnetic field the orientation of the spins are all: - ANSWER Random
As magnetic field strength increases the number of protons that align in the parallel
direction of the magnet: - ANSWER Increases
The summation of all the magnetic moments of individual spins along the surface plane of
the magnetic field is referred to as the: - ANSWER Longitudinal Magnetization Vector
(LMV)
Of the 3 magnet types used in MRI, the one used most is: - ANSWER Superconductive
Of the 3 magnet types used in MRI which can be routinely turned on and off: - ANSWER
Resistive
True/False: The magnetic field strength of an MRI system can be determined by looking at its
size: - ANSWER False
Of the 3 magnet types in MRI which is mostly used in "open" designs: - ANSWER
Permanent
Of the 3 magnet types used in MRI which can yield the highest magnetic field strength: -
ANSWER Superconductive
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,Of the 3 magnet types in MRI which is the heaviest: - ANSWER Resistive
Of the 3 magnet types in MRI which accommodates the highest performance levels in image
quality and speed: - ANSWER Superconductive
Of the 3 magnet types in MRI which requires special cooling to maintain its magnetic field: -
ANSWER Superconductive
In a superconductive magnet, electrical current flowing through the magnet experiences: -
ANSWER virtually no resistance
The medium used to make a conductor superconductive is called a: - ANSWER Cryogen
The strong magnetic field produced by heavy electric current passing through a conductor is
an example of: - ANSWER Faraday's Law
Helium liquifies a -453 degrees Fahrenheit which is equivalent to: - ANSWER 4 Degrees
Kelvin
0 Degree Kelvin, the theoretical point where all molecular motion stops, is also referred to
as: - ANSWER Absolute zero
The process of liquid helium explosively turning gaseous is referred to as: - ANSWER A
Quench
All MR systems have a transmitting antenna surrounding the patient referred to as: -
ANSWER The body coil
The computer component that performs the mathematical reconstruction of MRI images is:
- ANSWER Array Processor
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, The mathematical reconstruction of an MRI images uses the ____________ process to
create the image: - ANSWER Fourier Transform
When used properly, MRI has: - ANSWER No adverse biological effects
The amount of force a magnet exerts on an object depends on the: - ANSWER Amount of
ferrous material on the object and the distance to the center of the magnet
As the distance of an object to the magnet decreases, the force exerted on the object: -
ANSWER Increases
MRI related injuries are: - ANSWER Rare
MRI related accidents are: - ANSWER Rarely reported
Superconductive magnets use a ___________ to hold liquid helium: - ANSWER Cryostat
The liquid helium used in MRI is a type of: - ANSWER Cryogen
Helium liquifies at -453 degrees Fahrenheit or __________: - ANSWER 4 degrees Kelvin
An explosive conversion of liquid helium to gaseous helium is called a: - ANSWER Quench
A quench can either be _______________ or _______________: - ANSWER Controlled or
Uncontrolled
A release of helium into the magnet room can lead to death by: - ANSWER Asphyxiation
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