in a large main magnetic field such as those employed in MRI, the motion of a hydrogen proton has been described as wobbling like a spinning top. this motion is called
A) precession
B) resonance
C) frequency
D) angular momentum - ANSWER-precession
magnetic resonance imaging is derived from t...
Different tissues that have signals that appear similar on an MR image are described
as:
A) hypointense
B) hyperintense
C) isointense
D) isodense - ANSWER-isointense
in a large main magnetic field such as those employed in MRI, the motion of a hydrogen
proton has been described as wobbling like a spinning top. this motion is called
A) precession
B) resonance
C) frequency
D) angular momentum - ANSWER-precession
magnetic resonance imaging is derived from the process known as:
A) magnetic resonance angiography
B) magnetic relaxation imaging
C) nuclear magnetic resonance
D) nuclear resonance imaging - ANSWER-nuclear magnetic resonance
Once the nmv has moved away from equilibrium, the following will occur
A) the longitudinal component will increase
B) the transverse component will decrease
C) the longitudinal component will stay the same
D) the transverse component will increase - ANSWER-the transverse component will
increase
In MR, substances respond to a specific radio frequency which is known as:
A) magnetic frequency
B) radio frequency
C) gyro-magnetic frequency
D) resonance frequency - ANSWER-resonance frequency
the introduction of gadolinium based contrast enhancement agents by intra-venous
injection can involve passing through an abnormal blood brain barrier. the tissue
compartments involved are the:
A) intravascular to interstitial
B) extracellular to intracellular
,C) hepatobiliary to renal
D) extradural to renal - ANSWER-intravascular to interstitial
t2 is the measurement of time fot the transverse component of the NMV to decrease
what percentage of its maximum value after the application of a 90 degree radio-
frequency pulse
A) 33%
B) 63%
C) 37%
D) 67% - ANSWER-37%
in the USA, the MRI system's magnetic field and vector that represents it is symbolized:
A) B1
B) B2
C) B3
D) B0 - ANSWER-B0
The resonance frequency of any substance in a magnetic field can be calculated by
employing the
A) damadian equation
B) larmor equation
C) faraday equation
D) lauterbur equation - ANSWER-Larmor equation
in a pulse sequence, transmitting an initial 90 degree radio-frequency pulse will cause
the NMV to:
A) remain at equilibrium
B) shift in both size and direction
C) move to antiparallel
D) rephase - ANSWER-shift in both size and direction
Which type of electromagnetic coils are designed to stimulate and detect an MR signal?
A) gradient coils
B) radio-frequency coils
C) shim coils - ANSWER-radio-frequency
tissues that are less efficient at spin-spin interactions because they contain more free
water, such as CSF, should have
A) High T2 values and produce hypointense signals
B) HIgh T2 values and produce hyperintense signals
C) low T2 values and produce hypointnese signals
D) low T2 values and produce hyperintense signal - ANSWER-High T2 values and
produce hyperintense signals
magnetism can be defined as the ability of certain substances to attract:
A) Copper, aluminum, tin
the purpose of magnetic resonance angiography is to image the:
A) stationary soft tissue
B) blood flow
C) vessel lumen
D) only abnormal vessels - ANSWER-blood flow
the strength of very large magnetic fields like those employed in MRI systems, the SI
unit most commonly used is:
A) Tesla
B) Gauss
C) Kilogauss
D) militesla - ANSWER-Tesla
the larmor frequency of hydrogen protons in a 1.5 tesla magnetic field is:
A) 6.4 MHZ/Tesla
B) 12.8 MHz/Tesla
C) 25.5 MHz/tesla
D) 63.9 MHz/tesla - ANSWER-63.9 MHz/Tesla
In MR imaging, for chemical substance to be affected by the main magnetic field and
the radio-wave it must contain an:
A) Odd number of electrons
B) Odd number of total protons and neutrons
C) Even number of total electrons and neutrons
D) even number of protons - ANSWER-Odd number of total protons and neutrons
A 1.5T magnetic field is equal to:
A) 150 gauss
B) 1500 gauss
C) 15,000 gauss
D) 150,000 gauss - ANSWER-15,000 gauss
the components of the gyromagnetic ratio are:
A) stimulation to relaxation
B) protons to electrons
C) magnetic moment to angular momentum
D) main magnetic field to radio-frequency signal - ANSWER-magnetic moment to
angular momentum
fast transition phenomenon and entry phenomenon are theories that explain which of
the following characterisitics:
A) T1 effects
, B) T2 effects
C) hydrogen concentration
D) veolcity effects - ANSWER-Velocity effects
the effects of main magnetic field inhomogeneities on the FID signal are corrected for in
the spin echo sequence by applying a second radio frequency pulse. the flip angle of
this radio frequency pulse is:
A) 45 degrees
B) 60 degrees
C) 90 degrees
D) 180 degrees - ANSWER-180 degrees
of the following statements, which describes part of the basic MR imaging process:
A) a patient is placed isocenter to ionizing radiation
B) the patient is exposed to ionizing radiation
C) the generated image contains hypersense and hypodense areas
D) radio frequency signals interact with hydrogen protons - ANSWER-radio frequency
signals interact with hydrogen protons
which type of electromagnetic coils correct inhomogeneities in the main magnetic field?
A) gradient coils
B) radio frequency coils
C) shim coils - ANSWER-shim coils
immediately after an initial 90 degree radio frequency pulse is turned off, the hydrogen
protons will begin to:
A) Rephase
B) Dephase
C) Stay in the transverse plane
D) Stay in phase - ANSWER-Dephase
tissues that are very efficient at spin-lattice interactions near the larmor frequency, such
as fatty tissues should have:
A) Low T1 values and produce hyperintense signals
B) High T1 values and produce hyperintense signals
C) High T1 values and produce hypointense signals
D) Low T1 values and produce hypointense signals - ANSWER-Low T1 values and
produce hyperintense signals
T1 is the measurement of time for the longitudinal component of the NMV to recover
what percentage of its original value after the application of a 90 degree radio frequency
pulse?
A) 33%
B) 63%
C) 37%
D) 67% - ANSWER-63%
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