ARMRIT PHYSICS PRACTICE TEST
The tissue characteristic that depends heavily on the relative content of fat molecules
and free water is: - Answer- Hydrogen concentration.
T1 is the measurement of time for the longitudinal component of the net magnetization
vector to recover what percentage of its original value after the application of a 90
degree radio-frequency pulse? - Answer- 63%
Immediately after an initial 90 degree radio-frequency pulse is turned off, the hydrogen
protons will begin to: - Answer- Dephase
A 90 degree radio-frequency pulse will alter the net magnetization vector. Another effect
is: - Answer- The hydrogen protons will dephase
The basic process of MR signal generation contains two basic steps, they are: -
Answer- Stimulation and relaxation.
An equation derived to predict the MR signal intensity of a particular tissue as the result
of a Spin-echo pulse sequence is the: - Answer- Bloch equation
The component Mxy is most associated with: - Answer- Transverse to B0; T2 relaxation;
transverse magnetization
After a 90 degree radio-frequency pulse, the net magnetization vector begins to return
to equilibrium. When the NMV is half-way between transverse and equilibrium, what are
the magnitudes of the longitudinal component and the transverse component? -
Answer- Longitudinal component = greater than zero/transverse component = greater
than zero.
When is the net magnetization vector at its maximum magnitude? - Answer- At
equilibrium.
The Larmor frequency of hydrogen protons in a 1.5 Tesla magnetic field is: - Answer-
63.9 MHz/Tesla.
To describe the uniformity of the MRI system's main magnetic field, the term employed
is: - Answer- Homogeneity.
Tissues that are very efficient at spin-lattice interactions near the Larmor frequency,
such as fatty tissues, should have: - Answer- Low T1 values and produces hyperintense
signals
