Exam (elaborations)
MRI ARMRIT physics Questions and Answers 2024
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Exam of 5 pages for the course ARMRIT at ARMRIT (MRI ARMRIT physics)
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MRI ARMRIT physicsT2 is the measurement of time for the transverse component of the net magnetization
vector to decrease what percentage of its maximum value after the application of a 90
degree radio frequency pulse - answer37%
The NMV is rotated to the physical negative Z axis by applying a...? - answerC)180
pulse
Increasing which parameter is considered the "best" technique for improving image
quality? - answerC)NEX
Studies have concluded that static magnetic fields up to what tesla produce no
substantial harmful biological effects. - answerC)2.0
Tissues that have low (short) relaxation times have: - answerHigher relaxation rates
Nuclei in their natural enviroment ( in the absence of a significant magnetic field) are
aligned... - answerRandomly
Following the injection of a gadolinium enhancement agent, the pulse sequence most
commonly employed is a... - answerC)T1 weighted
Employing a pulse sequence with a long TR & a long TE will result in tissues with a
short T2 value appearing WHAT & tissues with a long T2 appearing WHAT on the
resultant image. - answerD)Dark/bright
Which gradient axis direction is typically (for educational purposes) designated as the
slice selection gradient? - answerC)Logical Z gradient
Electromagnetic coils placed strategically to contain the fringe fields. - answer2)Active
shielding
1 milliliter of H2O contains how many hydrogen protons? - answer6 ×10 to th 23power
Which of the following statements is true for gadolinium MRI IV enhancement products?
- answerB) produces randomly fluctuating magnetic fields in its immediate enviroment.
The maximum exposure to radiofrequency in 1 gram of tissue is: - answerD) a
maximum spatial peak of 8 w/kg
, Currently, patients & personnel arr exluded from exposure to MRI for the 1st trimester of
pregnancy. - answerTrue
The maximum exposure to radio frequency averaged over the head is: - answerB)No
more than 3.2 w/kg
The recieve signal amplitude for a pixel usually depends on thr substance's... -
answerA) T1, T2 , proton density
Small magnetic field intoduced to the hydrogen protons in order to cause them yo move
from the low energy state to the high energy state is.. - answerC) RF pulse
at any one time, human body tissue, in general, is made up of 50%-90% of what
substance? - answerHydrogen.
once the patient's area of interest is placed in the main magnetic field of the MRI
system, the hydrogen protons will... - answerprecess parallel to B sub zero
In most tissues hydrogen concentration varies - answer10%- to 15%
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? - answer63%
because of the spinning motion of the hydrogen proton, it has the same properties as a
bar magnet. the hydrogen proton spinning motion gives it a... - answermagnetic moment
Magnetic resonance imaging is derived from the process known as... - answerNuclear
magnetic resonance
normally enhancing structures post gadolinium - answerchoroid plexus
because of only a 10% to 15% variation in most tissues, the tissue character that does
not provide much contrast resolution... - answerhydrogen concentration
on T1 weighted images sub-acute hemorrhage will appear bright? - answertrue
which characteristic of tissue, in MRI, is the result of fast transition phenomenon &/or
entry phenomenon? - answerflow/velocity effects
radio frequency RF coils that are placed close to the patient's body specifically for
structures that are superficial & are receive coils only are... - answersurface coils
chemical shift artifacts will show up on the image in what gradient direction? -
answerfrequency encoding
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