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ARDMS - SPI Study Questions with
Complete Solutions
Which technique utilizes frequency modulation of the transmitted pulse to improve signal to noise ratio? ✔✔spatial compounding
Which angle of isonation to blood flow produces the maximum doppler shift? ✔✔180 degrees
Which imaging mode requires two elements mounted side by side? ✔✔continuous wave doppler
What is a benefit of using contrast agents? ✔✔increased amplitude of the returning dopplers
What is the most common cause of localized vertical nonuniformity in a real time b mode image? ✔✔improper time gain compensation
Which type of interaction between sound and tissue is most affected by the thermal index (TI)? ✔✔absorption
Which control allows adjustment for attenuation at specific depths? ✔✔Time gain compensation
Which condition must be present for refraction to occur? ✔✔a difference in tissue propagation speeds and oblique incidence
Which technique results in a three dimensional image? ✔✔surface rendering
Which action can improve axial resolution of a displayed image? ✔✔increasing the transducer frequency
short spl
damping
Which scenario will produce no doppler shift to the receiver? ✔✔source and receiver moving at the same speed and direction
Which technique the sharpness of high contrast boundaries? ✔✔edge enhancement
A sound wave propagates fastest through which substance?
Bone
Which term describes the averaging together of scan lines from multiple angles to create one image? ✔✔Spatial compounding
What would you do if you had aliasing in the pulsed wave? ✔✔1) drop baseline
increase scale
change to a lower transducer
What is the Nyquist limit? ✔✔1/2 PRF
What is the Nyquist limit if a pulsed doppler instrument has a pulse repetition frequency of 16 khz? ✔✔8 khz - 1/2 prf
What does coded excitation improve in addition to penetration? ✔✔lateral resolution
What does coded excitation improve? ✔✔Improves penetration, axial resolution, spatial resolution and contrast resolution
What is the potential affect of increasing prf? ✔✔depth ambiguity
depth ambiguity ✔✔the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed - can happen with increased prf
Which variable can cause an acoustic shadow artifact? ✔✔refraction
When using a 5 MHz transducer, in which tissue is the ultrasound wavelength the shortest? ✔✔Fat in this question
Use wavelength equation
speed over frequency
What is an advantage of using a pulsed wave doppler versus continuous wave doppler? ✔✔provides depth specificity
Which imaging mode requires a broadband transducer? ✔✔pulsed wave doppler
Which factor reduces the likelihood of aliasing in pulsed wave spectral doppler? ✔✔increased Nyquist limit
Large Diameter & High Frequency = ✔✔Less Divergence/Shallow focus
Small Diameter & Low Frequency = ✔✔More Divergence/Deep focus
Temporal resolution: ✔✔Best with faster frame rate
Best with shortest time to create image
Worse with mult focal zone & deeper imaging
Relates to frame rate & line density
Spatial resolution: ✔✔determined by # of pixels in scan converter
axial, lateral, elevational and contrast res.
improves with fill in interpolation
increases with decreased tx freq
Coded excitation: ✔✔a way of processing the pulse to improve contrast resolution
improves with axial and penetration
allows multi frequency of bflow imaging
reduces speckle
Attenuation ✔✔improves with tgc
Harmonics ✔✔non linear
improves lat resolution - has strong beams
elimnates near field artifacts
eliminates grating lobes
improves shadowing from calcifications
Dynamic range ✔✔use compression
elevational resolution ✔✔determined by the thickness of the imaging plane
perpendicular to scan plane
frame rate ✔✔improves signal to noise ratio
det. by speed of sound in medium and imaging depth
adjustable by depth
shallow has better higher frame rate
