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ARMRIT REVIEW TEST QUESTIONS AND ANSWERS
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ARMRIT REVIEW TEST QUESTIONS AND ANSWERS
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ARMRIT REVIEW TEST QUESTIONS AND ANSWERSThe exact middle of the bore of the magnet is termed: - Answers-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: - Answers-Including electrical current in the patient's tissues
Faraday's Law deals with induction of a current by a magnet. true or false? - Answers-
true
The orientation of the main magnetic field of a low field permanent magnet is vertical.
True or false? - Answers-True ; permanent lowfield magnets utilize a magnetic field
oriented vertically
Superconductive magnets have high homogeneity compared to other magnets types.
true or false? - Answers-true ; One advantage of a superconductive magnet is its
excellent homogeneity
The start up cost for a superconductive magnet is high. true or false? - Answers-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: - Answers-
Superconductive magnet
The basic type of magnets used in MR are: - Answers-Permanent, resistive ,
superconductive
A procedure called shimming: - Answers-Adjust the magnetic field to achieve the most
homogenous field
Superconductive magnets utilize two types of cyrogens. - Answers-Helium and nitrogen
Types of transmit coils are: - Answers-a) Body, b) head, c) volume coils, d) all of the
above. D all of the above
Various types of receiver coils are: - Answers-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: - Answers-Use a small surface coil
Which of the following is not an example of a surface coil: - Answers-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? - Answers-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: - Answers-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: -
Answers-Active- passive shielding can be accomplished by lining the walls with steel
while the more expensive alternative is active shielding
Surface coils are connected inside the scanner by cables. These cables shouldnt touch
the patient because: - Answers-They could burn the patient.
Quadrature design coils give you a lower SNR. true or false? - Answers-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?
- Answers-False: transmit coils are usually the body and head coils.
Magnetic field gradients are generated by what? - Answers-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? - Answers-evacuate all persons from the scan room.
The given field strength (ex..1.5T) of the magnet is maintained at the: - Answers-Middle
od the axis of the bore, middle of the axis reamins at the field strength.
When employing a surface coil the signal intensity: - Answers-decreases as anatomy
gets further from the coil.
Surface coils are "receive only" coils. true or false? - Answers-False
The largest possible receiver coil should be chosen: true or false? - Answers-False-
optimally smallest coils are best
Surface coils are free standing & have no electrical components. true or false? -
Answers-false
The precessonial frequency of hydrogen at 1.5T is 68MHz. true or false? - Answers-
False- Hydrogen @1.5T is 63.86MHz
, What happens to the precessional frequency of those protons which experience a
higher magnetic field? - Answers-It increases
To achieve the shortest scan time possible, which of the following would not be
selected. - Answers-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? - Answers-4.2 minutes; 1x128x2/60=4.2
In MR , the frequency of water is_________ as compared to the frequency of fat. -
Answers-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: - Answers-
Nyquist Theorem
If the Nyquist theorem is not adhered to in the MR experiment what is the result? -
Answers-Aliasing
At equilibrium more nuclear spines are________ with the magnetic field. - Answers-In
Alignment
When the magnetic field is energized the nuclear spins start to return to process, as
they return to equilibrium they give of: - Answers-NMR signal
Repeatedly applying RF pulses at time internals less than the T2 & T1 times of the
tissues refers to: - Answers-A steady state- a steady state is a condition where the TR is
shorter than the T1 & T2 times of tissues.
In an MRI expirement , what occurs first after RF excitation - Answers-T2* Decay
The most widely used pulse sequence is: - Answers-Spin-Echo
For the spin-echo pulse sequence, FID is the signal used to
create the image. true or false? - Answers-False- pulse sequence echoes are the MR
signals that make an image in SE scans
The signal produced immediately after a RF pulse is: - Answers-FID - signal produced
immediately after a RF pulse.
Which of the following is not an intrinsic parameter effecting image contrast? - Answers-
Repetition time
At 1.0T fat has a T1 relaxation time of approximately: - Answers-180msec
At 1.0T the T2 relaxation time of water is approximately: - Answers-2500msec
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