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DAVIES SPI: IV. Pulse-Echo
Instrumentation (30% of ARDMS) Exam
Graded A+.
What is a typical frame rate for B-mode real-time imaging? A. 1-9 kHz B. 10-50 Hz C. 100-200 MHz D. 200-300 Hz E. 0.05-0.9 Hz - correct answer B. 10-50 Hz <Frame rates are displayed in terms of Hz, a unit of frequency equal to one cycle per second. Although frame rates vary, typical real-time frame rates range from 10 Hz to 50 Hz. If the frame rate is 30 Hz, that means 30 frames are produced in one second. Faster frame rates are found with cardiac imaging> What component is necessary for a real-time B-mode scanner but is not present in A-mode scanner? A. Clock B. Transmitter C. Transducer D. Scan converter E. Receiver - correct answer D. Scan converter You have increased the output power by 10 dB. The signal intensity has: A. Doubled B. Tripled C. Quadrupled
D. Increased by a factor of 10 E. Increased by a factor of 100 - correct answer D. Increased by a factor of 10 <Increasing a control by 3 dB corresponds to a doubling of the setting. If it is increased by 10 dB, it has been increased by a factor of 10> In this illustration, letter A is demonstrating what type of resolution? A. Axial B. Lateral C. Elevational D. Contrast E. Temporal - correct answer B. Lateral What function of the receiver converts electric signals from radiofrequency to video form? A. Amplification B. Compensation C. Compression D. Demodulation E. Rejection - correct answer D. Demodulation <Demodulation is accomplished by rectification and smoothing (filtering). Demodulation may also be called amplitude detection or envelope detection> The range equation describes the relationship between: A. Acoustic impedance of two media B. Side-lobe intensity between two crystals C. Round-trip pulse travel time and distance to the reflector
D. Doppler effect E. None of the above - correct answer B. Echo ranging What is the source of the echoes depicted by the arrows in this image of the kidney? A. Side lobes B. Grating lobes C. Refraction D. Reverberation E. Multipath reflections - correct answer D. Reverberation Preprocessing functions may be defined as: A. Any function that can be performed on a frozen image B. A function that takes place in the beam former and is not controllable by the operator C. A function that allows increased focusing of the sound beam D. A function that is performed before the echo data are stored in memory E. Any function that changes the quality of the ultrasound image - correct answer D. A function that is performed before the echo data are stored in memory <Any function that occurs after this point is referred to as postprocessing. The easiest way to distinguish pre- and postprocessing functions is this: If it can't be performed on a frozen image, it is preprocessing; if it can be performed on a frozen image, it is postprocessing> Which term below most correctly describes this Doppler waveform?
A. Aliasing B. Spectral mirroring C. Spectral broadening due to sample volume size D. Reverberation E. Bidirectional flow - correct answer B. Spectral mirroring You have decreased the scan line density. What technique will be employed to fill in the empt data between the scan lines? A. Interpolation B. Rejection C. Compression D. Autocorrelation E. Demodulation - correct answer A. Interpolation Which of the following ultrasound examinations would require the highest frame rate? A. Small parts B. Abdominal C. Pelvic D. Vascular E. Cardiac - correct answer E. Cardiac <Since the heart is a rapidly moving structure, high frame rates are required to assess it accurately>
What type of imaging results in selective reception of frequencies that are two times that of the transmitted frequency? A. Color Doppler imaging B. Pulsed Doppler imaging C. Tissue Doppler imaging D. M-mode imaging E. Tissue harmonic imaging - correct answer E. Tissue harmonic imaging <In tissue harmonic imaging, the receiver selectively "listens" to the harmonic frequencies that are generated as the sound travels through the tissue. The second harmonic is the strongest harmonic produced. This is twice the transmitted frequency> You are manipulating a volume data set that was previously obtained on your patient. What is the maximum number of imaging planes that can be obtained from this data set? A. One B. Ten C. One hundred D. One thousand E. There is no limit - correct answer E. There is no limit Pulse repetition period is the inverse of: A. Duty factor B. Pulse repetition frequency
C. Frame rate D. Pulse duration E. Spatial pulse length - correct answer B. Pulse repetition frequency <PRP is the time between the pulses, wehreas PRF is the number of pulses that occur in one second> Which of the following is associated with improper adjustment of the brightness and contrast on the video monitor? A. The spatial resolution of the resultant image will be degraded B. The operator will likely overgain or undergain the image C. The temporal resolution will be reduced D. The flicker rate of the video monitor will be increased E. The penetration of the transducer will be reduced - correct answer B. The operator will likely overgain or undergain the image <The amount of gain the operator applies is subjectively determined by the appearance of the image brightness. If the monitor is set too dark, the operator may overgain the image to compensate for the dark monitor. If the monitor is too bright, the operator may undergain the image to compensate> In order for distance measurements to be accurate in an ultrasound tissue phantom, the phantom sound propagation speed must be: A. 13 μs/cm B. 1.54 m/s C. 1540 m/s D. Half the speed of sound in tissue E. Twice the speed of sound in soft tissue - correct answer C. 1540 m/s The term signal-to-noise ratio denotes:
D. Brightness and contrast settings of the monitor E. Interpolation scheme - correct answer A. Number of pixels in the scan converter matrix <A matrix of 512 x 512 pixels is capable of much better spatial resolution than a similarly sized matrix containing only 64 x 64 pixels. In the latter example, the image would appear blocky with discrete square-shaped segments. Image resolution would be degraded> What is an advantage of a water-path scanner? A. Near-field reverberations are reduced B. Penetration is increased C. Temporal resolution is improved D. Axial resolution is improved E. Slice thickness is reduced - correct answer A. Near-field reverberations are reduced A type of sonographic imaging that transmits two pulses of opposite phase in rapid succession so they can be cancelled out upon reception is termed: A. Pulse inversion harmonics B. Compound imaging C. Speckle reduction imaging D. Tomographic imaging E. Panoramic imaging - correct answer A. Pulse inversion harmonics <Pulse inversion harmonics is an effective method to filter out the fundamental frequency (transmitted frequency) and leave only the harmonic frequencies for display. It uses two pulses of opposite polarity transmitted into the tissue in rapid succession. The received echoes from the pulses are added together and will cancel out the transmitted frequency, leaving the harmonics that were generated within the tissue>
What can you do improved visualization of distal acoustic shadowing from calcification? A. Compound imaging B. Tissue harmonic imaging C. Speckle reduction imaging D. 3D imaging E. Tomographic ultrasound imaging - correct answer B. Tissue harmonic imaging You have obtained an ultrasound image that demonstrates refraction of the sound beam. The artifact might be manifested as: A. Axial displacement of a reflector B. Enhancement distal to a reflector C. Lateral displacement of the displayed position of a reflector D. Multiple images of a single reflector E. Increased brightness of a reflector - correct answer C. Lateral displacement of the displayed position of a reflector <Refraction is a bending of the sound beam. Because the system must assume that the ultrasound is coursing straight from the transducer face, refraction results in a misplacement of the reflectors laterally> What receiver function is responsible for decreasing the difference between the smallest and largest received signal amplitudes? A. Amplification B. Compensation
<A volume data set may be obtained by a freehand sweep of the probe over the anatomy or by an automated sweep of the transducer within the probe. Automated 3D sweeps can be obtained with specially designed mechanical or electronic transducers. One advantage of the automated method is that measurements can be accurately obtained because the distance of the sweep is known> Complete destructive interference of echo reflections will affect the display in the following way: A. By creating bright white pixels B. By creating black pixels C. By creating dark gray pixels D. By creating light gray pixels E. None of the above - correct answer B. By creating black pixels When you select harmonic imaging, which artifact is less likely to be observed? A. Refraction B. Shadowing C. Ring-down D. Grating lobes E. Speed of sound - correct answer D. Grating lobes Which imaging technique may increase visualization of the reflections from blood flow on the real-time ultrasound image? A. Compound imaging B. Tissue harmonic imaging C. 3D imaging D. Tomographic imaging E. Speckle reduction imaging - correct answer B. Tissue harmonic imaging
<Moving blood flow is more likely to be seen on the real0time ultrasound image with tissue harmonic imaging because of the reduced clutter, improved contrast resolution, and higher frequency (which results in greater scattering from the RBCs since they are Rayleigh scatterers> A group of 8 bits is called: A. Binary B. Kilobyte C. Pixel D. Byte E. Matrix - correct answer D. Byte What imaging artifact is much worse on the left phantom image compared to the right phantom image? A. Reverberation B. Volume averaging C. Range ambiguity D. Multipath E. Refraction - correct answer B. Volume averaging What is the purpose of the preamplification of the incoming signal that occurs in the transducer assembly? A. To decrease the dynamic range of the signal B. To increase echo voltages before noise is induced through the cable C. To reduce sensitivity to side lobes D. To reduce acoustic impedance mismatch between the tissue and the transducer E. To compensate for attenuation of the beam width depth - correct answer B. To increase echo voltages before noise is induced through the cable
When you select compound imaging, which artifact is less likely to be observed? A. Refraction B. Shadowing C. Enhancement D. Acoustic speckle E. All of the above - correct answer E. All of the above <Since the beam is steered at the anatomy from multiple directions and formed into a composite image, some artifacts are less likely to be observed with compound imaging> Which of the following will decrease the presence of the artifact you are seeing in the previous question? A. Using frame averaging (persistence) B. Using compound imaging C. Reducing the output power D. Increasing the overall gain E. A and B - correct answer E. A and B Which of the following helps to improve the lateral resolution in a B-mode image? A. Increased aperture B. Increased bandwidth C. Focusing with an acoustic lens D. Increased dynamic range E. Beam steering - correct answer A. Increased aperture What information is present in the M-mode display?
A. Time, motion pattern, and amplitude B. Amplitude, frequency, and time C. Motion patter and frequency D. Time, motion patter, and frequency E. Bandwidth, amplitude, frequency, time, and motion pattern - correct answer A. Time, motion pattern, and amplitude When you "freeze" the ultrasound image, where is the echo information stored? A. Transducer B. Scan converter C. Cable D. Beam former E. Receiver - correct answer B. Scan converter What effect will you detect in the image if you increase the threshold control? A. Increased image brightness B. Decreased image brightness C. Decreased appearance of weak echo signals D. Increased appearance of strong echo signals E. Decreased appearance of strong echo signals - correct answer C. Decreased appearance of weak echo signals <"Threshold" is another name for the reject control. It is used to reduce the display of weak echo signals that most likely arise from electronic noise. Increasing the threshold reduces the display of weak signals> Selective reception of echoes generated within the body by nonlinear propagation describes:
ambiguity results. In other words, the system cannot accurately detect the depth of the returning echo and will assume it arrived from the most recently transmitted pulse. This will cause the reflector to be misplaced axially on the image in a position relating to a more superficial structure. If sound traveled faster in tissue, the maximum PRF could be increased. Unfortunately, the speed of sound in tissue is determined by the medium through which it travels and cannot be adjusted by the operator or the system> You are imaging a fluid-filled structure that has equidistant horizontal bands appearing in the near field. The bands have decreasing brightness with depth. What artifact are you seeing? A. Slice-thickness B. Side lobes C. Reverberation D. Comet-tail E. Ring-down - correct answer C. Reverberation What control should you adjust to optimize the image if you are scanning a structure that produces very bright echoes on the display? A. Rejection B. TGC C. Edge enhancement D. Frame averaging E. Frequency - correct answer B. TGC Where are images stored in the ultrasound system? A. Pulser B. Receiver C. Beam former D. Display
E. Scan converter - correct answer E. Scan converter Which of the following helps to improve the axial resolution in a B-mode imaging? A. Increased aperture B. Increased bandwidth C. Focusing with an acoustic lens D. Increased dynamic range E. Beam steering - correct answer B. Increased bandwidth Which technology would be most helpful to obtain accurate anatomic volume measurements? A. 2D imaging B. 3D imaging C. Color Doppler imaging D. Harmonic imaging E. Compound imaging - correct answer B. 3D imaging <3D imaging is helpful for measuring anatomic volumes, especially those that are irregularly shaped> While performing an ultrasound examination, you decide to adjust the system settings to improve the image. Which of the following is NOT user-adjustable? A. Frequency B. Power C. Gain D. Compression E. Echo arrival time - correct answer E. Echo arrival time
