Ch. 1 & 9 Flashcards
Turbulent flow:
a. should not be mistaken for pathology
b. always occurs at vessel bifurcations
c. is associated with vessel bends and kinks
d. indicates stenosis exceeding 60%
b. always occurs at vessel bifurcations
what would happen to the frequency component of this waveform if the transmitted doppler frequency (Ft) was 2.5 MHz?
Decrease by factor of 2
in the doppler equation for velocity what is the Cos (theta)?
the doppler beam angle of incidence to flow.
in the linear array transducers, doppler steering is accomplished by which of the following methods?
phasing
what’s causing this peripheral arterial waveform to look “goofy”?
(look at image)
high wall filter
a color doppler image on most ultrasound systems is generated by which process?
autocorrelation
which of the following is an advantage of continuous-wave doppler over pulsed-wave doppler specifically for segmental pressure determination?
b-mode image is not necessary for vessel location
which of the following is not a product of color autocorrelation?
peak frequency shift
why is the measured velocity in this image inaccurate?
angle adjustment cursor not aligned correctly
some ultrasound systems can enable a high PRF mode in which the spectral doppler PRF is doubled. which of the following is resulting artifact?
multiple sample gates.
this doppler waveform is derived from what type of processing or analysis?
(look at image)
zero crossing detection
which of the following does not affect color frame rate?
color gain
what pulse-wave doppler parameter is decreased when the range gate is reduced in size?
spatial pulse length
to improve the AXIAL resolution of an image you could
increase the transmit frequency.
which of the following principles, effects or laws apply to decreased pressure with increase flow speed?
bernoulli’s effect
laminar flow is disrupted and turbulence occurs when the reynolds number meets or exceeds what value?
2000
this equation: E (energy)= I (current) x R (resistance) is called __________
and is often used as an analogy to ___________
Ohm’s law, poiseuille’s law
the highest pressure in the arterial system is found in what region or organ?
left ventricle of the heart
which of the following arterial wall structures is in direct contact with blood flow?
endothelium
perfusion in tissue is controlled by vasoconstriction and vasodilation in which of the following structures
arterioles
which of the following is not a risk factor for peripheral arterial disease?
venous reflux/insufficiency
what is the most significant factor affecting diastolic blood flow in the lower extremities
vasoconstriction/dilation in the arterioles
the vaso vasorum supplies blood flow to what structure
arterial wall
of the symptoms listed below, which is generally not associated with arterial insufficiency?
limb swelling
