RVT Questions

What doppler angle of insonation is recommended for accurate velocity measurements?

60 degrees or less

What are advantages of CW?

Not specific for depth

Valuable for obtaining systolic blood pressures in lower arterial exams

No aliasing

Can measure higher velocities

formula for SPL

SPL= # of cycles x wavelength

number of pulse-echo cycles occurring in 1 sec

PRF

When does aliasing occur?

doppler shift exceeds ½ PRF

Ways to eliminate aliasing

shift baseline

increase PRF

use CW

increase doppler angle

decrease doppler transmit frequency (higher the doppler angle, lower frequency shift)

decrease sample volume depth

Operator should keep the wall filter below ___Hz? to detect venous flow

100Hz

If wall filter is set to high what happens to the spectral waveform?

It eliminates low velocities

What is optimal doppler frequency for 1-2cm depth?

4.5-6.0 Mhz Doppler

What is optimal doppler frequency for >5cm depth?

1.8-2Mhz Doppler

Color Doppler uses ___ to generate a color image

autocorrelation

Autocorrelation

analyzes multiple pulses sent along a scan line for frequency shift at various depths

high number of pulses per line does what to the frame rate?

decreases frame rate

high transmit frequency ____ axial resolution

increases

Variables that effect color frame rate

packet size (pulses per line)

density of scanlines

PRF

color box width

color box depth

Cannot obtain a doppler velocity at what angle?

90 degrees

How can you improve lateral resolution?

focus

How can you improve axial resolution?

increase frequency

How can you improve “Z axis”? (aka elevation plane- slice thickness of the beam)

changing frequencies so that the fixed focal zone is within the target vessel

What can happen if other vessels lie in the beam path and align with one of the “non-primary” sample gates?

Doppler Range gate Depth Ambiguity occurs causing the system to be unable to distinguish the primary doppler signal

If the transmitted doppler frequency was 2.5 instead of 5Mhz what would happen to the frequency component?

a. no change

b. increase by 2

c. decrease by 2

decrease by 2

In the doppler equation for velocity, what is cosine theta?

the doppler angle of incidence to flow

In linear array transducers, doppler steering is accomplished by which of the following methods?

phasing

optical lens

mechanical adjustment of piezo elements

phasing

what process is used to generate color doppler on most ultrasound machines?

FFT

Time domain imaging

autocorrelation

autocorrelation

which of the following is an advantage of CW over PW specifically for segmental pressure determination?

B-Mode image is not necessary for vessel location

higher transmit frequency

can process venous and arterial signal together

no aliasing

B- Mode not necessary for vessel location

Autocorrelation provides the following information

direction

average or mean frequency shift

power

variance (frequency spread / turbulence)

Some ultrasound systems can enable a high PRF mode in spectral Doppler to double doppler the PRF. Which of the following is a resulting artifact ?

Mirror image

Increased aliasing

spectral broadening

multiple sample gates

multiple sample gates

Decreasing SPL does what to axial resolution?

Improves axial resolution

which of the following controls does not affect color frame rate?

packet size

color gain

color scan line density

color box width

color gain

Difference between zero crossing detection and FFT

Zero crossing displays a single line on spectral doppler representing average frequency shift and direction. In contrast FFT displays peak, mean, and Lowest frequencies

What PW doppler parameter is decreased when the range gate is reduced in size?

PRF

LATERAL RES

SPL

SPL (remember decreasing SPL improves axial resolution and decreasing range gate improves axial res)

If the doppler beam is steered to 20 degrees what is the doppler angle of incidence in a horizontal vessel?

70 degrees (hint: subtract degree of steering from 90 degree incidence since the vessel is horizontal)

What function would improve axial resolution?

adjust elevation plane focal zone

add focal zones

decrease transmit frequency

increase transmit frequency

increase transmit frequency

When obtaining a peak systolic velocity measurement using duplex ultrasound imaging, the doppler angle cursor should be adjusted____ to the vessel wall.

Parallel

Which of the following is the average propagation speed of sound in soft tissue? 1540m/s

1540cm/s

1450m/s

1540m/s

Why is doppler PRF inherently lower when a sample volume is placed in a deep vessel?

There is a longer time interval between transmitting pulses, so pulse repetition is delayed; slower, and hence, lower PRF. The pulsed doppler system transmits a pulse and waits for a specific interval (set by the SV depth) before resending a pulse

The benefit of matrix or 2D linear array transducer is the ability to focus in which of the following planes?

elevation plane

lateral (azimuth) plane

axial plane

longitudinal plane

Elevation plane

completed brain stroke

CVA (cerebrovascular accident)

stroke like symptoms that resolve within 24 hours

TIA (transient ischemic attack)

symptoms that resolve, but not within 24 hours

RIND (reversible ischemic neurological deficit)

paralysis on the rt side would be caused by a stroke on what side of the brain?

left-brain stroke

inability to speak or express oneself

aphasia

strokes that cause apashia are usually on what side of the brain?

dominant hemisphere- usually left

impairment of speech, lack of coordination and failure to arrange words in proper order

dysphasia

what hemisphere is impaired with dysphasia?

dominant

difficulty swallowing

dysphagia

imperfect articulation of speech due to disturbances of muscular control, slurring, etc

dysarthria

tingling and numbness

lateralized paresthesia

impairment of what hemisphere causes paresthesia?

contralateral

lateralized weakness

hemiparesis

lateralized paralysis

hemiplegia

transient monocular blindness (TMB)

Amaurosis fugal

amaurosis fugax is caused by atheroemboli emboli to the retinal artery and _____ (ipsilateral? or contralateral?) carotid artery

ipsilateral

gross incoordination of muscle movements, clumsiness of limb

ataxia

what hemisphere is associayed with ataxia?

contralateral

what are vertebral-basilar ischemic symptoms?

syncope

vertigo

dizzines

diplopia

drop attacks

binocular blindness

double vision

diplopia

falling down without fainting

drop attacks

a transient state of being unconscious without losing consciousness

syncope

a sense of being off balance

dizziness

a sense that the environment is moving around the patient

vertigo

What are the causes of stroke?

cardiac origin

carotid origin

cerebral aneurysm rupture

miscellaneous- vasospasm from sickle cell anemia or AVMs

stroke from cardiac origin is usually due to ____

atrial fibrillation

Most common location for emboli distally along a cerebral vessel?

MCA

what percent of strokes are hemorrhagic in nature?

15%

a spasm of the intracranial arteries following a subarachnoid hemorrhage that can lead to stroke

vasospasm

brachiocephalic artery bifurcates into

rt common carotid and rt subclavian artery

What are some anomalous origins of Left CCA?

Brachiocephalic artery

T/F: Anomalous origins of other aortic arch branches is not uncommon

true

vertebral arteries originate from

subclavian arteries

distal vertebral arteries form

basilar artery

what artery has spinal branches that allow cross-filling to the other side

vertebral artery

bifurcation of the CCA occurs at what level of the vertebrae?

C3-C4

What monitors blood pressure? and where are these located?

baroreceptors located in carotid bulb

what is 1st branch of ICA?

OPTHALMIC ARTERY

What supplies the retinal artery of the eye?

ophthalmic artery

What supplies the thyroid, facial muscles, pharynx, other glands, etc.

ECA

First branch of ECA is typically?

superior thyroid artery

What supplies blood to the posterior hemispheres of the brain via the posterior cerebral arteries?

basilar artery

What supplies blood to frontal lobes?

anterior cerebral artery

what supplies blood to posterior hemispheres?

PCA

What connects proximal MCAs or distal ICAs

PCoA (posterior communicating arteries)

What connects the left and right ACAs?

anterior communicating arteries (ACoA)

Circle of Willis is about the size of ?

human thumbnail

What percentage of people have the classic Circle of Willis configuration ?

25%

What percentage of the population has an intact and functioning circle of willis?

50%

What artery is essential for cross-filling for patients with an occluded or severely stenosed ICA?

Anterior communicating artery

The best acoustic window for the ICA is usually from the

posterolateral approach

anterolateral approach

lateral approach

posterolateral

best window for the ECA is usually found with the transducer positioned

anterolaterally

ICA typically lies more posterior or anterior to ECA

posterior

What percentage of the population has the “wishbone” or tuning fork carotid bifurcation?

15-20%

Methods of differentiating ICA vs ECA

ECA has extracranial branches

ICA low resistance flow pattern

ICA is usually larger in diameter than the ECA

“Temporal tap”

echolucent =

anechoic

ability to create an ultrasound echo

echogenic

producing echoes of lower amplitude than normal for the surrounding medium

hypo echoic

sonolucent=

anechoic

A 75% area reduction is = to what % diameter reduction?

50%

When imaging the carotid if depth penetration is an issue what should you do to the color box and angle of the transducer?

Unsteer the color box and heel toe

What things should you do to optimize color doppler?

beam steering

color scale

color gain

adjust color box width

assign correct color assignment for arteries and veins

other controls: packet size, scan line density, color maps, color filters