WorksheetsMRI Midterms
Total questions: 53
Worksheet time: 32mins
The major component of the MR system in the _____ is the magnet itself.
magnet room
MRI room
magnetic room
MR room
An electromagnet which mostly made of selenoid.
Strong magnets
Resistive Magnet
Permanent Magnet
Superconducting magnets
A type of magnet that can produce up to 6 Tesla.
Strong magnets
Resistive Magnet
Permanent Magnet
Superconducting magnets
A type of magnet that does not require cryogens in the system.
Strong magnets
Resistive Magnet
Permanent Magnet
Superconducting magnets
A type of magnet that is dependent to the power supply.
Strong magnets
Resistive Magnet
Permanent Magnet
Superconducting magnets
The use of this magnet for the MRI system have high electricity cost.
Strong magnets
Resistive Magnet
Permanent Magnet
Superconducting magnets
The field strength of resistive magnets
less than 0.3T
up to 0.3T
more than 0.3T
0.5 - 1.5T
Consist of blocks or slabs of naturally occurring ferrous material
Strong magnets
Resistive Magnet
Permanent Magnet
Superconducting magnets
Permanent magnets have field strength of
0.3 - 0.4 T
0.6 - 0.35 T
0.5 - 1.5 T
0.06 - 0.35 T
Describe the relationship of the quantity of magnet materials and field strength.
Inversely proportional
Directly proportional
No direct relationship
Indirectly proportional
Sudden and violent loss of superconductivity
hysteresis
quench
fringe
decay
As time goes by, the magnetic field of a permanent magnet weakens
hysteresis
quench
fringe
decay
How to increase the field strength and homogeneity of the magnets?
increase the number of magnets
reduce the number of magnets
increase the gap between two magnets
decrease the gap between two magnets
The portion of the magnetic field extending away from the confines of the magnet that cannot be used for imaging but can affect nearby equipment or personnel.
hysteresis
quench
fringe field
decay
Present in permanent MRI systems; direction of the magnetic field
Vertical field
Horizontal field
Oblique Field
Transverse Field
Horizontal magnetic field is found in what MRI system
Permanent
Resistive
Superconducting
Strong
Vertical field magnet design uses 2 magnets, one above and one below the patient
(a)
Certain nuclei have properties that cause them to display magnetic properties.
(a)
Magnetic moment is based on the magnetic field of
electron
proton
Neutron
quarks
Net strength and orientation of a magnetic field
angular momentum
magnetic moment
net magnetization
precession
The angle formed between a precessing object and its imaginary axis
angular momentum
magnetic moment
net magnetization
precession
The sum of the contributions of all magnetic moments of the individual protons
angular momentum
magnetic moment
net magnetization
precession
change in the orientation of the rotation axis of a rotating body.
angular momentum
magnetic moment
net magnetization
precession
The axis of the nucleus forms a path around B0 known as the
(a)
The speed at which hydrogen precesses depends on the strength of BO (magentic field) and is termed the
(a)
The precessional paths of the individual hydrogen nucleus’ is random, or
(a)
the RF used in MRI is in the form of a burst of RF energy (pulse) in the _____ range
10 - 20 MHz
20 - 100 MHz
10 - 200 MHz
100 - 200 MHz
The term returning to equilibrium is called relaxation and can be thought of as a two-step process
(a)
T1 relaxation
(a)
Transverse relaxation
(a)
Proponent of Larmor equation
Sir Joseph Larmor
Sir John Larmor
Sir James Larmor
Sir Jb Larmor
It is the frequency at which the hydrogen precess
(a)
Gyromagnetic ratio of hydrogen
40000 kHz
42600 kHz
10.7 MHz
5800 kHz
They are made to improve Signal-to-noise ratio (SNR) by detecting both halves of the MR Signal.
shim coils
quadrature coil
gradient coil
RF coil
surface coils
(a)
head, body, or extremity coils
(a)
It contains the main magnet and several other electromagnetic devices essential to MRI.
(a)
The following can be found inside the gantry, except.
Radiofrequency coil
Patient Table
Shim coils
High Voltage Generator
Generally used computers in MRI.
Macrocomputers
Minicomputers
Microcomputers
Mainframe Computer
The following are connected to the RF coils, except.
RF detector
Pulse program
Digitizer
Gradient amplifier
The most important part in the MRI
(a)
Massive size, 3M across by 3M high, with a length of 5M.
Superconducting MRI system
Resistive MRI system
Permanent MRI system
Strong MRI system
Usually the (a) are at room temperature, unlike the primary magnet that is immersed in the liquid helium.
2 large coils produce the magnetic field, whereas the 2 smaller coils on each end help to extend the length of the field and make it uniform
Superconducting MRI system
Resistive MRI system
Permanent MRI system
Strong MRI system
You can perceived the primary magnet.
Superconducting MRI system
Resistive MRI system
Permanent MRI system
Strong MRI system
carry a relatively small current that are used to provide auxiliary magnetic field to compensate for inhomogeneities in the Bo.
(a)
There are no shim coils in this system.
Superconducting MRI system
Resistive MRI system
Permanent MRI system
Strong MRI system
Shimming the primary magnetic field is accomplished by (a) adjusting the 2 finely machined pole pieces.
Superconducting magnet can produce magnetic field strength up to 35T.
True
False
Most common type of shimming
(a)
A superconducting magnet generates 15000 G and was directed to an iron steel. Determine its precessional frequency.
1.2 MHz
2.1 MHz
21000 MHz
12000 MHz
A Sodium-23 atom precesses at 680 kHz due to the magnetic field induced by the magnet. Using the Larmor equation, determine the strength of external field. (Show your solution)
Freddie is currently studying an atom that precesses at 54342 kHz in the presence of 23500 G. He wants to identify the gyromagnetic ratio of the atom. Help Freddie achieve his goal. (Show your solution)
