Blood flow that has consistent velocities within a vessel is known as what type offlow
Turbulent flow
Laminar flow
Vortex flow
Stagnant flow
Blood flow that has randomly different velocities is known as what type of flow
Blood flow that has high velocities in the center of the vessel but spirals near walls of a vessel due to a stricture is known as what type of flow
Blood flow that slows to a point of immobility is known as what type of flow
Blood flow velocity is measured in what type of unit
Gauss/sec
mm/sec
cm/sec
inches/sec
Which of the following is the formula that is used to calculate blood flow velocity
Velocity = Flow volume / Vessel area
Velocity = Vessel area / Flow volume
Velocity = Flow volume + vessel area
Velocity = Vessel area - Flow volume
Blood flow velocity is greatest near which area of the vessel
Vessel walls
Vessel center
None of the above
Blood flow velocity at a given point is dependent upon which factor
Patient sex
Phase of patient's cardiac cycle
Patient's weight
During peak systolic phase of the cardiac cycle, blood flow velocities are dependent upon what factor(s)
Patient age
Cardiac output
Anatomical site
Patient age, Cardiac output & Anatomical site
Which of the following vessels has the highest peak velocity
Ascending aorta
Distal aorta
Proximal carotids
Basilar artery
Which of the following vessels has the slowest peak velocity
Middle cerebral arteries
Proximal carotid arteries
Venous vessels
Typical peak velocities of the ascending aorta are usually within what range
150 - 175 cm/sec
100 - 160 cm/sec
80 - 120 cm/sec
40 - 70 cm/sec
Typical peak velocities of the distal aorta and iliac vessels are usually within what range
Typical peak velocities of the proximal carotid, brachial and superficial femoral arteries are usually within what range
Typical peak velocities of the middle and anterior cerebral arteries are usually within what range
100 - 150 cm/sec
30 - 50 cm/sec
Typical peak velocities of the vertebral and basilar arteries are usually within what range
50-70 cm/sec
30-50 cm/sec
under 20 cm/sec
The speed at which blood flows through an excited slice and only receives one RF pulse is known as what type of phenomenon
Time of flight phenomenon
Entry slice phenomenon
Intra-voxel dephasing
To produce signal in a spin echo pulse sequence, blood flow must receive both the 90 degree and the 180 degree RF pulse.
True
False
Blood flow that receives a 90 degree excitation pulse but not a 180 degree rephasing pulse produces what type of signal
High signal
Low signal
No signal
Blood flow that receives a 180 degree rephasing pulse but not a 90 degree excitation pulse produces what type of signal
The magnitude of time of flight phenomenon effects is dependent upon which factor(s)
Velocity of flow
TE
Slice thickness
All of the above
As blood flow velocity increases, the effects of time of flight phenomenon
Increase
Decrease
Stays the same
As blood flow velocity decreases, the effects of time of flight phenomenon
Increases
Decreases
As the echo time increases, the effects of time of flight phenomenon
Stay the same
As echo time decreases, the effects of time offlight phenomenon
As slice thickness increases, the effects of time of flight phenomenon
As slice thickness decreases, the effects of time of flight phenomenon
In a gradient echo pulse sequence, blood flow that receives the initial RF pulse produces what type of signal
High
Low
The flow phenomenon that is characterized by the contrast differences between fresh flowing nuclei entering a slice and stationary tissue within that slice is known as
Entry slice phenomenon is most prominent in what slice of the area scanned
First slice
Middle slice
Last slice
Affects all the same
The effects of entry slice phenomenon are dependent upon which factor(s)
Repetition time
When TR is decreased, the effects of entry slice phenomenon
When TR is increased, the effects of entry slice phenomenon
When slice thickness is increased, the effects of entry slice phenomenon
When slice thickness is decreased, the effects of entry slice phenomenon
When the velocity of flow increases, the effects of entry slice phenomenon
When the velocity of flow decreases, the effects of entry slice phenomenon
The direction of blood flow is an important factor in determining the effects of entry slice phenomenon
Blood flow that travels in the same direction in which the slices are acquired is known as what type of flow
Counter current flow
Co-current flow
Blood flow that travels in the opposite direction in which the slices are acquired is known as what type of flow
When the direction of blood flow is opposite the direction in which slices are acquired, the effects of entry slice phenomenon
When the direction of blood flow is the same as the direction in which slices are acquired, the effects of entry slice phenomenon
The flow phenomenon that is characterized by phase differences between flowing and stationary nuclei within a voxel is known as
The magnitude of intra-voxel dephasing is dependent upon which factor(s)
Degree of disruption in the flow
Echo time
In which of the following types of flow can intra-voxel dephasing be compensated for
The use of an additional gradient to correct the effects of intra-voxel dephasing is a technique known as
Gradient moment rephasing
Intra-voxel misregistration
Gradient moment nulling
Gradient moment rephasing & Gradient moment nulling
Gradient moment nulling is most effective on which type of flow
Slow turbulent flow
Fast laminar flow
Slow laminar flow
Fast vortex flow
The effects of time of flight and entry slice phenomena can be minimized by which method
Pre-saturation RF pulse
Respiratory compensation
The method of acquiring more than one echo that are multiples of each other to reduce intra-voxel dephasing is known as
Even echo rephasing
Which of the following conventional MRI techniques can be used to produce contrast differences between vascular structures and stationary structures
Pre-saturation pulse
Gradient moment nulling & Pre-saturation pulse
Which of the following is the conventional technique used to produce a black appearance in vascular structures
Short TE, Short TR, Pre-saturation pulse
Long TE, Short TR, Gradient moment nulling
Long TE, Long TR, Respiratory compensation
Which of the following is the conventional technique used to produce a bright appearance in vascular structures
The vascular imaging method that maximizes vascular contrast while also suppressing stationary tissue is known as
Magnetic resonance mammography
Magnetic resonance angiography
Black Blood imaging
Zeugmatography
Which of the following is a method used inMRAto suppress stationary tissue
Tissue subtraction
Tissue saturation
Gradientmomentnulling
Tissue subtraction & Tissue saturation
Which of the following is a method used in MRA to increase signal from vascular structures
Subtraction
Bipolar gradient
Gradient moment nulling & Bipolar gradient
The type of MRA that uses gradient echo pulse sequences and gradient moment nulling to enhance flow is known as
Digital subtraction
TOFMRA
PCMRA
Velocity encoding
In TOF MRA, which method is used to suppress signal from stationary tissue?
Saturation
TOF MRA is most sensitive to blood flow that flows in what direction in relation to the slice
Parallel
Perpendicular
Which of the following is a disadvantage of TOF MRA
Parallel flow can be suppressed
Slow flow can be suppressed
Stationary tissue with short Tl relaxation times can produce signal
Which of the following is an advantage of TOF MRA
Relatively short scan times
Increased sensitivity to flow
Decreased sensitivity to intra-voxel dephasing
Which of the following TOF MRA sequences is most likely to saturate slow flow
3DTOF
2DTOF
The type of MRA that produces image contrast based on the differences in phase shifts between blood flow and stationary tissue is known as
None ofthe above
Which of the following type of MRA uses a bipolar gradient to enhance vascular structures
Bright blood imaging
Phase contrast MRA
Which of the following is a type of image that is produced by phase contrast MRA?
Magnitude image
Frequency image
Phase image
Magnitude image & Phase image
Which of the following is an advantage of phase contrast MRA
Increased stationary tissue suppression
Sensitive to flow in all directions
Sensitive to flow with various velocities
Which of the following is a disadvantage of phase contrast MRA
Long scan times
Reduced intra-voxel dephasing
Increased sensitivity to turbulence
Long scan times & Increased sensitivity to turbulence
Which of the following PC MRA techniques provides the highest signal to noise ratio and spacial resolution
2DPCMRA
3DPCMRA
The method that is most commonly used to reduce artifact produced by cardiac motion when scanning the chest is known as
Respiratory gating
Cardiac gating
Two types of cardiac gating that are most commonly used are known as
Respiratory gating, Respiratory compensation
ECG gating, Peripheral gating
Pseudo gating, Respiratory gating
The P wave of the ECG represents which phase of the cardiac cycle
Atrial systole
Ventricular systole
Ventricular diastole
Atrial diastole
The QRS wave of the ECG represents which phase of the cardiac cycle?
The T wave of the ECG represents which phase of the cardiac cycle
During cardiac gating, which wave is used to trigger each pulse sequence
P wave
Q wave
R wave
T wave
During cardiac gating, the time between two consecutive R waves is known as
Trigger window
Trigger delay
R-R interval
The ECG wave with the highest electrical amplitude is known as the
During cardiac gating, TR is dependent upon which factor(s)
The patient's heart rate
The R- R interval
The Q - R interval
The patient's heart rate & The R- R interval
During cardiac gating, which factors are affected by having an effective TR
Image weighting
Number of slices
Scan time
During cardiac gating, the waiting time between the R wave and the start of the data acquisition is known as
Inversion time
Echo delay
During cardiac gating, the waiting time before each R wave is known as
During cardiac gating, which of the following is the formula used to calculate available imaging time
F=yBo
Time = R-R interval- (trigger window + trigger delay)
Time R-R interval + (trigger window + trigger delay)
The type of cardiac gating that detects the increase in blood volume in the capillary bed during systole is known as
ECG gating
Pseudo gating
Peripheral gating
During cardiac gating, one R-R interval and a short TE is used to produce what type of image
T1 weighting
T2 weighting
Proton density weighting