Ultrasound Physics + Echocardiography Questions with Correct Answers
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Course
Echocardiography
Institution
Echocardiography
The human ear can perceive sounds up to _______, above which sounds are referred to as "ultrasound."
a. 5 kHz
b. 20 kHz
c. 5 MHz
d. 20 MHz Correct Answer-B: 20 kHz. Ultrasound frequencies in imaging are usually 3-12 MHz
The piezoelectric effect refers to converting ____ energy into ____ ene...
Ultrasound Physics + Echocardiography Questions
with Correct Answers
The human ear can perceive sounds up to _______, above which sounds
are referred to as "ultrasound."
a. 5 kHz
b. 20 kHz
c. 5 MHz
d. 20 MHz Correct Answer-B: 20 kHz. Ultrasound frequencies in
imaging are usually 3-12 MHz
The piezoelectric effect refers to converting ____ energy into ____
energy. Correct Answer-Electrical energy into kinetic or mechanical
energy.
Which of the following is NOT a parameter to be considered when
minimizing ultrasound-induced thermal injury?
a. Haired/non-haired skin
b. Exposure time
c. Protein content of tissue
d. Perfusion of tissue
e. Emission modality (e.g. B-mode vs. pulsed-wave)
f. Beam width
g. Pulse repetition frequency
h. Size of scanned area
,i. Focus depth
j. Frequency Correct Answer-A. Protein content in tissue is directly
related to absorption coefficient. The higher the absorption coefficient
the greater the temperature increase in tissues during ultrasound (e.g.
bone has the highest absorption coefficient and temperature rise). Deep
focus and decreased frequency requires an increase in power which
increases heating damage.
T/F: Ultrasound-induced biologic effects may include endothelial
damage with secondary thrombus formation and cellular injury via free
radical production. Correct Answer-TRUE. Thrombus formation was
one of the earliest demonstrations of its biologic effects
How does the process of acoustic cavitation lead to tissue damage? What
is a clinical example of the deleterious effects of cavitation? Correct
Answer-The interaction of ultrasound with gas bubbles (e.g. lungs,
intestines) causes rapid and potentially large changes in bubble size
(cavitation). This may increase temperature and pressure within the
bubble and cause mechanical stress on surrounding tissues, precipitate
fluid microjet formation, and generate free radicals. Pulmonary
hemorrhage is a well-studied example of cavitation - hemorrhage
originates from microvasculature of the visceral pleura.
Acoustic impedance = ___________ x __________ Correct Answer-
Velocity/speed of ultrasound waves X density of tissue
How does using a harmonics mode improve tissue contrast? Correct
Answer-The transmitted pulse deforms as it travels through tissues from
a perfect sinusoid to a sharper, sawtooth shape which causes a change in
,the reflected echoes. Using higher-order harmonic echoes instead of just
listening for the fundamental echo (initial pulse wave) results in
improved image contrast and reduced noise.
Which of the following components comprise ultrasound contrast media:
a. Nitrogen gas
b. Helium gas
c. Fluorocarbon Gas
d. Lipoprotein shell
e. Lipid shell
f. Glycoprotein shell Correct Answer-C, D
T/F: When using contrast-enhanced ultrasound, neoplastic liver lesions
have a bright appearance (increased contrast uptake) when compared
with normal liver at peak normal liver perfusion. Correct Answer-
FALSE - Neoplastic lesions lack a portal venous blood supply and
remain hypoperfused at peak enhancement of the normal liver
parenchyma (i.e. dark).
What determines the amount of the sound beam being reflected? Correct
Answer-1. Difference in acoustic impedance between different tissues
(the velocity of sound within each tissue and the tissue's density), the
greater the difference, the greater the reflection
2. Angle of incidence, the higher the angle of incidence (the closer it is
to the right angle), the more beams reflected
, Refracted beams hit interface and continue forward in a different
direction. Reflected beams hit interface and come back to the probe.
The ability to resolve two different reflectors (resolution) depends on
_______ and ________. Correct Answer-Spatial pulse length
(wavelength x number of cycles per each pulse (= frequency))
Distance between the reflectors
The reflectors are resolved only when the spatial pulse length/2 is
greater than the distance between the reflectors. Therefore, the shorter
the wavelength (the higher the frequency at a constant sound speed), the
shorter the spatial pulse length, the closer the reflectors to be resolved,
the higher the resolution.
Fill in the blanks in the chart:
CHART Correct Answer-CHART
How does the ultrasound cause tissue heating? Which ultrasound
application in particular increases the risk of this? and explain the
principle of prevention of this. Correct Answer-Absorption due to the
frictional forces that oppose the motion of the particles in the medium .
Mechanical energy (sound waves) into thermal energy
Doppler ultrasonography (longer pulse durations and higher pulse
repetition frequencies are used in Doppler ultrasonography)
ALARA (as low as reasonably achievable)
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