different tissues that have signals that appear similar on an MRI are described as -
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 -
answer precession
MRI is derived from the process known as - answer nuclear magnetic resonance
once the NMV has moved away from equilibrium, what will occur - answer the
transverse component will increase
in MRI, substances respond to a specific radio frequency which is known as - answer
resonance frequency
the introduction of gad based contrast agents by IV injection can involve passing
through the BBB, what are the tissue compartments involved - answer intravascular to
interstitial
T2 is the measurement of time from the transverse component of the NMV to decrease
what percentage of its max value after the application of a 90 degree RF pulse -
answer37%
in the USA, the MRI's main magnetic field and the vector that represents it is
symbolized - answerBo
the resonance frequency of any substance in a magnetic field can be calculated by
employing the - answerLarmor equation
in a pulse sequence, transmitting an initial 90 degree RF pulse will cause the NMV to -
answershift in both size and direction
which type of electromagnetic could are designed to stimulate and detect an MR signal -
answerRF coils
tissues that are less efficient at spin spin interactions because they contain more free
water such as CSF should have - answerhigh T2 values and produce hyperintense
signals
, magnetism can be defined as the ability to attract certain substances such as -
answeriron, cobalt, and nickel
the purpose of MRA is to image the - answerblood flow
the strength of very large magnetic fields like those employed in MRI systems, the SI
unit most commonly used is - answertesla
the larmor frequency of hydrogen protons in a 1.5 T magnetic field is -
answer63.9MHz/tesla
in MRI, for a chemical substance to be affected by the main magnetic field and the radio
wave it must contain - answeran odd number of total protons and neutrons
a 1.5T magnetic field is equal to - answer15,000 gauss
the components of the gyro magnetic ratio are - answermagnetic momentum to angular
momentum
fast transition phenomenon and entry phenomenon are theories that explain which of
the following tissue characterists - answervelocity effects
the effects of main magnetic field inhomogenities on the FID signal are corrected in a
spin echo sequence by applying a second RF pulse. the flip angle of this RF pulse is -
answer180 degrees
describe the basic MR imaging process - answerRF signals interact with hydrogen
protons
which type of electromagnetic coils correct inhomogenities in the main magnetic field -
answershim coils
immediately after an initial 90 degree RF pulse is turned off, the hydrogen protons will
begin to - answerdephase
tissues that are very efficient at spin lattice interactions near the larmor frequency, such
as fatty tissue, should have - answerlow T1 values and produces 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 RF pulse -
answer63%
the tissue characteristic which depends more on the state (solid, liquid, or gas) of a
tissue than any other factor is - answerT2 effects
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