The exact middle of the bore of the magnet is termed: - ANSWER Isocenter
Without proper safety limits on the MR system exposure to the time-varying magnetic fields
created by the rapid switching of the gradient could create a potential environment for: -
ANSWER Including electrical current in the patient's tissues
Faraday's Law deals with induction of a current by a magnet. true or false? - ANSWER
true
The orientation of the main magnetic field of a low field permanent magnet is vertical. True
or false? - ANSWER True ; permanent lowfield magnets utilize a magnetic field oriented
vertically
Superconductive magnets have high homogeneity compared to other magnets types. true or
false? - ANSWER true ; One advantage of a superconductive magnet is its excellent
homogeneity
The start up cost for a superconductive magnet is high. true or false? - ANSWER true ;
Initial cost may exceed two million dollars in addition to the expensive cyrogen up keep.
A type of magnet that is generally used for a 1.0t or a 1.5t system is a: - ANSWER
Superconductive magnet
The basic type of magnets used in MR are: - ANSWER Permanent, resistive ,
superconductive
1
,A procedure called shimming: - ANSWER Adjust the magnetic field to achieve the most
homogenous field
Superconductive magnets utilize two types of cyrogens. - ANSWER Helium and nitrogen
Types of transmit coils are: - ANSWER a) Body, b) head, c) volume coils, d) all of the
above. D all of the above
Various types of receiver coils are: - ANSWER a) solenoidal coil, b)
volume,birdcage,surface coil, c) Helmholtz pair coil, d) All of the above: D all of the coils are
true receiver coils
To gain SNR and gain high resolution: - ANSWER Use a small surface coil
Which of the following is not an example of a surface coil: - ANSWER body coils are not
surface coils
In a cross-sectional view of the magnet bore, which set of coils are the closest to the bore? -
ANSWER RF coil- the cross sectional of the MR system reveals the order of thecoils: the
magnet bore, then the RF coils, Then the gradient coils, then the shim coils & the outer most
are magnet coils.
MR systems can be shielded by two processes. They are: - ANSWER Passive and active
shielding
The more expensive type of shielding that uses additional solenoid magnets outside the
cyrogen bath that restricts the magnetic field line to an acceptable location is the: -
ANSWER Active- passive shielding can be accomplished by lining the walls with steel
while the more expensive alternative is active shielding
2
,Surface coils are connected inside the scanner by cables. These cables shouldnt touch the
patient because: - ANSWER They could burn the patient.
Quadrature design coils give you a lower SNR. true or false? - ANSWER True: Quadrature
coil designs improve SNR due to increased coverage.
The two coils in a magnet used to transmit RF are the shim and tune coils. true or false? -
ANSWER False: transmit coils are usually the body and head coils.
Magnetic field gradients are generated by what? - ANSWER coils of wire situated within
the bore of the magnet.
In the event of a cryogenic leak or catastrophic magnet quench, the first thing the
technologist should do is? - ANSWER evacuate all persons from the scan room.
The given field strength (ex..1.5T) of the magnet is maintained at the: - ANSWER Middle
od the axis of the bore, middle of the axis reamins at the field strength.
When employing a surface coil the signal intensity: - ANSWER decreases as anatomy gets
further from the coil.
Surface coils are "receive only" coils. true or false? - ANSWER False
The largest possible receiver coil should be chosen: true or false? - ANSWER False-
optimally smallest coils are best
Surface coils are free standing & have no electrical components. true or false? - ANSWER
false
3
, The precessonial frequency of hydrogen at 1.5T is 68MHz. true or false? - ANSWER False-
Hydrogen @1.5T is 63.86MHz
What happens to the precessional frequency of those protons which experience a higher
magnetic field? - ANSWER It increases
To achieve the shortest scan time possible, which of the following would not be selected. -
ANSWER Shortest TE possible. TE doesnt effect scan time
In a 2DFT scan using a TR of 1 second, a TE of 30msec, a FOV 24, Matrix 128 & 2 NSA. What
is your total scan time for 1 slice? - ANSWER 4.2 minutes; 1x128x2/60=4.2
In MR , the frequency of water is_________ as compared to the frequency of fat. -
ANSWER Higher- The frequency in H2O is higher than fat
The following statement: Any signal must be sampled at least twice per cycle in order to
represent or reproduce it accurately; is a mathematical principle called: - ANSWER
Nyquist Theorem
If the Nyquist theorem is not adhered to in the MR experiment what is the result? -
ANSWER Aliasing
At equilibrium more nuclear spines are________ with the magnetic field. - ANSWER In
Alignment
When the magnetic field is energized the nuclear spins start to return to process, as they
return to equilibrium they give of: - ANSWER NMR signal
Repeatedly applying RF pulses at time internals less than the T2 & T1 times of the tissues
refers to: - ANSWER A steady state- a steady state is a condition where the TR is shorter
than the T1 & T2 times of tissues.
4
Without proper safety limits on the MR system exposure to the time-varying magnetic fields
created by the rapid switching of the gradient could create a potential environment for: -
ANSWER Including electrical current in the patient's tissues
Faraday's Law deals with induction of a current by a magnet. true or false? - ANSWER
true
The orientation of the main magnetic field of a low field permanent magnet is vertical. True
or false? - ANSWER True ; permanent lowfield magnets utilize a magnetic field oriented
vertically
Superconductive magnets have high homogeneity compared to other magnets types. true or
false? - ANSWER true ; One advantage of a superconductive magnet is its excellent
homogeneity
The start up cost for a superconductive magnet is high. true or false? - ANSWER true ;
Initial cost may exceed two million dollars in addition to the expensive cyrogen up keep.
A type of magnet that is generally used for a 1.0t or a 1.5t system is a: - ANSWER
Superconductive magnet
The basic type of magnets used in MR are: - ANSWER Permanent, resistive ,
superconductive
1
,A procedure called shimming: - ANSWER Adjust the magnetic field to achieve the most
homogenous field
Superconductive magnets utilize two types of cyrogens. - ANSWER Helium and nitrogen
Types of transmit coils are: - ANSWER a) Body, b) head, c) volume coils, d) all of the
above. D all of the above
Various types of receiver coils are: - ANSWER a) solenoidal coil, b)
volume,birdcage,surface coil, c) Helmholtz pair coil, d) All of the above: D all of the coils are
true receiver coils
To gain SNR and gain high resolution: - ANSWER Use a small surface coil
Which of the following is not an example of a surface coil: - ANSWER body coils are not
surface coils
In a cross-sectional view of the magnet bore, which set of coils are the closest to the bore? -
ANSWER RF coil- the cross sectional of the MR system reveals the order of thecoils: the
magnet bore, then the RF coils, Then the gradient coils, then the shim coils & the outer most
are magnet coils.
MR systems can be shielded by two processes. They are: - ANSWER Passive and active
shielding
The more expensive type of shielding that uses additional solenoid magnets outside the
cyrogen bath that restricts the magnetic field line to an acceptable location is the: -
ANSWER Active- passive shielding can be accomplished by lining the walls with steel
while the more expensive alternative is active shielding
2
,Surface coils are connected inside the scanner by cables. These cables shouldnt touch the
patient because: - ANSWER They could burn the patient.
Quadrature design coils give you a lower SNR. true or false? - ANSWER True: Quadrature
coil designs improve SNR due to increased coverage.
The two coils in a magnet used to transmit RF are the shim and tune coils. true or false? -
ANSWER False: transmit coils are usually the body and head coils.
Magnetic field gradients are generated by what? - ANSWER coils of wire situated within
the bore of the magnet.
In the event of a cryogenic leak or catastrophic magnet quench, the first thing the
technologist should do is? - ANSWER evacuate all persons from the scan room.
The given field strength (ex..1.5T) of the magnet is maintained at the: - ANSWER Middle
od the axis of the bore, middle of the axis reamins at the field strength.
When employing a surface coil the signal intensity: - ANSWER decreases as anatomy gets
further from the coil.
Surface coils are "receive only" coils. true or false? - ANSWER False
The largest possible receiver coil should be chosen: true or false? - ANSWER False-
optimally smallest coils are best
Surface coils are free standing & have no electrical components. true or false? - ANSWER
false
3
, The precessonial frequency of hydrogen at 1.5T is 68MHz. true or false? - ANSWER False-
Hydrogen @1.5T is 63.86MHz
What happens to the precessional frequency of those protons which experience a higher
magnetic field? - ANSWER It increases
To achieve the shortest scan time possible, which of the following would not be selected. -
ANSWER Shortest TE possible. TE doesnt effect scan time
In a 2DFT scan using a TR of 1 second, a TE of 30msec, a FOV 24, Matrix 128 & 2 NSA. What
is your total scan time for 1 slice? - ANSWER 4.2 minutes; 1x128x2/60=4.2
In MR , the frequency of water is_________ as compared to the frequency of fat. -
ANSWER Higher- The frequency in H2O is higher than fat
The following statement: Any signal must be sampled at least twice per cycle in order to
represent or reproduce it accurately; is a mathematical principle called: - ANSWER
Nyquist Theorem
If the Nyquist theorem is not adhered to in the MR experiment what is the result? -
ANSWER Aliasing
At equilibrium more nuclear spines are________ with the magnetic field. - ANSWER In
Alignment
When the magnetic field is energized the nuclear spins start to return to process, as they
return to equilibrium they give of: - ANSWER NMR signal
Repeatedly applying RF pulses at time internals less than the T2 & T1 times of the tissues
refers to: - ANSWER A steady state- a steady state is a condition where the TR is shorter
than the T1 & T2 times of tissues.
4
