ARMRIT Practice test – Flashcards
Unlock all answers in this set
Unlock answersquestion
Magnetism can be defined as the ability of certain substances to attract:
answer
Iron, Cobalt, Nickel
question
The components of the Gyro-magnetic ratio are:
answer
Magnetic moment to angular momentum
question
Which type of electromagnetic coils produce smaller magnetic field which allow spatial localization to be performed?
answer
Gradient coils
question
Which type of MRI magnet requires cryogen to cool magnetic coils to 4 degrees Kelvin?
answer
Superconductive
question
T2 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:
answer
37%
question
Which cryogenic material can produce temperature as low as 4 degrees Kelvin?
answer
Liquid Helium
question
The T1 process is also known as
answer
Spin-Lattice
question
a 90 degree radio-frequency pulse will alter the net magnetization vector. Another effect is:
answer
The hydrogen protons will have phase coherence.
question
Which type of MRI magnet requires no electricity to maintain its magnetic field and can weigh from 18,000 lb. to 200,000 lb.?
answer
Permanent
question
To describe the uniformity of the MRI system's main magnetic field, the term employed is
answer
Homogeneity
question
The purpose of magnetic resonance angiography is to image the
answer
Blood Flow
question
Magnetic Resonance Imaging is derived from the process known as:
answer
Nuclear Magnetic resonance
question
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:
answer
Intravascular to interstitial
question
In a pulse sequence, transmitting an initial 90 degree radio-frequency pulse will cause the net magnetization vector to:
answer
Shift in both size and direction.
question
Which statement is true of the relaxation process?
answer
Without the effects of T2 star, T2 decay continues.
question
Which molecule precesses closer to the Larmor frequency?
answer
Fat
question
1 milliliter of H2O contains how many hydrogen protons
answer
6 times 10 ^22
question
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
question
Which type of MRI magnet requires a steady current of electricity in coils of conductor wrapped around an air or iron core?
answer
resistive
question
What is the gyro-magnetic ratio of hydrogen?
answer
42.58 MHz
question
Of the following statements, which describes part of the basic MR imaging process?
answer
Radio-frequency signals interact with hydrogen protons.
question
Which type of MRI magnet has attainable field strengths of 0.35 Tesla to 3 Tesla for clinical use in the U.S.A, and higher strengths elsewhere and in research?
answer
Superconductive
question
The mechanism of T2 contrast enhancement agents is to
answer
decrease T2 relaxation time, therefore producing low signal.
question
The effects of main magnetic field inhomogeneities on the FID signal are corrected for in a Spin-echo sequence by applying a second radio-frequency pulse. The flip angle of this radio-frequency pulse is:
answer
180 degrees
question
Which type of electromagnetic coils can be found both inside and outside of the housing of the MRI magnet?
answer
radio-frequency coils
question
At any one time, human body tissue, in general, is made up of 50-90 percent of what substance?
answer
H2O
question
In comparison to Computed Axial Tomography, an advantage of MRI is
answer
Superior soft-tissue contrast resolution
question
In MRI, substances respond to a specific radio frequency which is known as:
answer
Resonance frequency
question
In the USA, MRI systems in clinical use have main magnetic field strengths that range from:
answer
0.06 Tesla to 3 Tesla
question
Magnetic fields have strength and direction, which are represented by a:
answer
Vector
