SPI PRACTICE TEST #5

1. True or False. The lower the numerical value of the longitudinal resolution, the worse the picture produced by an ultrasound system. True. False.

2. True or False. The more cycles there are in a pulse, the greater the detail that will be visualized in the ultrasound scan. True. False.

3. True or False. The pulse duration does not profoundly influence the lateral resolution. True. False.

4. True or False. The higher the frequency of the cycles within a pulse, the lower the value of the axial resolution. True. False.

5. True or False. The shorter the pulse length, the better the picture. True. False.

6. True or False. One way that a sonographer can alter the axial resolution achieved during an exam is to adjust the maximum imaging depth. True. False.

7. True or False. The shorter the pulse duration, the better the picture. True. False.

8. True or False. The length of a pulse does not directly influence the temporal resolution. True. False.

9. True or False. With a specific ultrasound system and transducer, the system's range resolution is invariant, and therefore the sonographer can do nothing to improve it. True. False.

10. The lateral resolution of an ultrasound system is primarily determined by the ____________. width of the sound pulse. length of the ultrasound pulse. duration of the sound pulse. none of the above.

11. The focus of an ultrasound beam is the location where the ___________ . beam is the broadest. optimum transverse resolution is found. frequency is the highest. finest depth resolution is obtained.

12. Two ultrasound systems have near zone lengths of 8 cm. At the focus, System G has a lateral resolution of 3.0 mm while System P has a lateral resolution that measures 5.0 mm. Which system is most likely to produce higher quality pictures at their foci?. System P. System G. both will produce similar quality pictures.

13. True or False. In comparison to other locations along the length of an ultrasound beam, focusing is generally ineffective in the far zone. True. False.

14. Two ultrasound systems have near zone lengths of 8 cm. At the focus, System S has a lateral resolution of 3.0 mm while System C has a lateral resolution that measures 5.0 mm. Which system is most likely to appropriately display two small body structures that lie, one in front of the other, at depths of 8.6 and 9.0 mm?. System C. System S. both have comparable quality. cannot be determined.

15. Two ultrasound systems are being evaluated. Both have near zone lengths of 8 cm. At their foci, System Q has a lateral resolution of 3.0 mm and System H has a lateral resolution of 5.0 mm. Which system will correctly display two small structures that lie in the body at a depth of 8 cm? The objects are side-by-side and are 0.4 cm apart. System H. System Q. both will produce similar quality pictures.

16. The lateral resolution of an ultrasound system is 4 mm. Two structures are 3 separated by 3 mm and lie side-by-side in relation to the long axis of the acoustic beam. What will most likely appear on the display of the system?. two weak echoes, 4 mm apart. two bright echoes, 3 mm apart. one echo. two bright echoes, 7 mm apart.

17. True or False. When using an instrument typical of standard ultrasonic imaging instrumentation, the lateral resolution has a higher value than the axial resolution. True. False.

18. True or False. When using an instrument typical of today's imaging devices, a higher frequency transducer is likely to mildly improve the system's transverse resolution. True. False.

19. True or False. When using an instrument typical of today's diagnostic imaging devices, a higher frequency transducer is likely to improve the system's range resolution. True. False.

20. What will lower the value of an ultrasound system's lateral resolution?. decrease the number of cycles in the pulse. increase the effective damping material. increase the pulse repetition period. send the pulse through an acoustic lens.

21. Which of the following will improve a system's temporal resolution?. increased sector angle. increased line density. increased PRF. increased frequency.

22. Focusing is most effective in which region of an acoustic beam?. the very shallow near zone. the end of the near zone. very deep in the far zone. throughout its entire length.

23. The diameter of a disc-shaped, unfocused piezoelectric crystal is 1 cm. What is the best estimate for the minimum lateral resolution of the ultrasound system?. 1 mm. 5 mm. 1 cm. 5 cm.

24. The diameter of a unfocused, disc-shaped piezoelectric crystal is 1.2 cm. The near zone length is 8 cm. What is the best estimate for the lateral resolution at 16 cm?. 0.6 cm. 1.2 cm. 8 cm. 16 cm.

25. Two ultrasound systems are identical except for the diameter of the transducer's piezoelectric crystal. Which system has the farthest focus?. the system with the smaller diameter crystal. the one with the larger diameter crystal. their foci will be at the same depth.

26. Two ultrasound systems are identical except for the frequency of the emitted pulse. Which system will have the farthest focus?. the lower frequency system. the higher frequency system. both foci will be at the same depth.

27. Two ultrasound systems are identical except for the pulse repetition period of the emitted pulse. Which system will have the farthest focus?. the system with the lower pulse repetition period. the system with the higher pulse repetition period. their foci will be at the same depth.

28. True or False. An ultrasound system with a longer pulse duration will generally have better temporal resolution. True. False.

29. True or False. An ultrasound system with a lower pulse repetition period will generally have better temporal resolution than a system with a higher pulse repetition period. True. False.

30. True or False. The biological effects of ultrasound are thought to be negligible, and therefore few investigations have been performed on the subject. True. False.

31. True or False. It is generally believed that the effects of ultrasound on biologic media are minimal. True. False.

32. True or False. It is generally believed that the biological effects of ultrasound at intensity levels typically produced by diagnostic imaging equipment are minimal. True. False.

33. Which of the following is not considered a potential mechanism for the production of bioeffects from ultrasound exposure to the body?. temperature elevation. fractionation. cavitation. mechanical trauma.

34. A comprehensive and scholarly review of bioeffects was performed by the American Institute of Ultrasound in Medicine for all of the following reasons except: ultrasound is a versatile technique. ultrasound has proven widespread clinical utility. ultrasound is considered highly toxic. applications of ultrasound are growing considerably.

35. Which of the following is not a valid rationale for establishing quantitative safety guidelines for the use of ultrasound?. they would be applicable and appropriate for a majority of clinical situations. the FDA would then have a scientific basis for regulation of the industry. manufacturers would have guidelines for system design. it would reduce concern of the patient community.

36. Which of the following does not contribute to the difficulty in establishing standardized guidelines for the use of diagnostic ultrasound?. the risks are small and hard to measure. scientists are not convinced of the potential for bioeffects in man at standard diagnostic imaging intensities. there are many varied ultrasound systems and the exams performed are diverse. it is difficult to measure the intensity of ultrasound beams in vitro.

37. Some studies of ultrasonic bioeffects are performed in vivo. What does this term mean?. observable in a living body. observations based on an experiment. discernible in a test tube. perceptible in a plant.

38. True or False. The mechanistic approach to the study of bioeffects and safety includes the identification of a theoretical construct that could produce an effect. True. False.

39. True or False. The empirical approach to the study of bioeffects and ultrasonic safety surveys data in hopes of finding a relationship between exposure and toxic effects. True. False.

40. True or False. A bioeffect identified via the mechanistic approach rather than by the empirical approach is most likely to have clinical significance. True. False.

41. True or False. The AIUM considers an ultrasound-induced biologic tissue temperature rise of less than 1° Centigrade above normal body temperature as safe for clinical studies. True. False.

42. According to the AIUM, at what in situ tissue temperature is there danger to a fetus?. 100° C. 98.6° F. 1° F above normal body temperature. 41° C.

43. Of the following choices, which variable is considered the most important for the sonographer with regard to bioeffects?. pulse repetition frequency. frequency. duration of the study. imaging mode.

44. Which of the following ultrasound beams has a characteristic that is most likely to cause temperature elevation in soft tissue?. strongly focused. medium focused. unfocused.

45. Which of the following statements regarding cavitation is true?. it has never been observed in biologic media. transient rather than stable cavitation is more likely to occur with diagnostic imaging. it is a nonlethal bioeffect produced in animal experiments. waves with peak pressures less than 10 MPa can never induce cavitation.

46. Research has indicated that cavitation ____________. never occurs. cannot occur with short pulses. can be lethal to living things. effects are purely theoretical.

47. What is epidemiology the study of?. large groups. the prevalence of disease. acoustic bioeffects on the fetus. in vitro effects.

48. Many epidemiologic studies of in utero exposure to ultrasound have concentrated on all of the following findings except ______. head circumference. birth weight. cancer. structural abnormalities.

49. What does the statistical power of an epidemiologic study indicate?. how conclusive the results are. agreement on the study's conclusions by the medical community. the probability that the results are valid. the number of observations required to yield a statistically valid result.

50. What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects?. 1 mW/cm². 100 mW/cm². 1000 mW/cm². 1 W/cm².

51. The upper limit for the SPTA intensity of a focused ultrasound wave where there have been no observed bioeffects is ________. 1 mW/cm². 10 mW/cm². 100 mW/cm². 1 W/cm².

52. True or False. One reason why focused ultrasound beams with low intensities are less likely to cause bioeffects is that a focused beam is less efficient in heating a large mass of tissue to a critical temperature. True. False.

53. True or False. Focused ultrasound beams are considered less likely to create bioeffects because they will strike fewer gas bubbles that could potentially cavitate. True. False.

54. Certain studies of bioeffects are performed in vitro. What does in vitro mean?. visible in a living organism. observations based on experiments. discernible in a test tube. perceptible in a living human being.

55. True or False. The AIUM suggests that in vitro research confirming bioeffects are valuable and valid. Their results are significant and should be directly applied to the clinical arena. True. False.

56. Acoustic artifacts include: (More than one answer may be correct). images of reflectors in an inappropriate position. images that have reflectors of improper shape. images of reflectors of incorrect brightness. images that do not correspond to anatomical structures.

57. Ultrasound systems are designed with which of the following characteristics in mind?. to automatically display similar structures with identical intensities, regardless of depth. to automatically position structures at the correct depth, regardless of the medium. to automatically display all reflections on a line corresponding to the major axis of the ultrasound beam, regardless of refraction. to automatically select the optimal beam width based on the clinical application.

58. Which of the following is not a potential cause of artifact in diagnostic imaging?. operator error. equipment malfunction. patient motion. ultrasound physics. none of the above.

59. What is true of artifacts related to depth resolution?. too many reflectors are displayed on the image. position reflectors too deep on the image. too few reflectors are on the image. position reflectors displayed too shallow on the image.

60. Axial resolution artifacts are due to which of the following?. multiple reflections. beam width. attenuation. pulse length.

61. Which of the following pulses would be least likely to produce a radial resolution artifact?. 10 MHz, 8 mm diameter, 4 cycles per pulse. 4 MHz, 4 mm diameter, 2 cycles per pulse. 7.5 MHz, 8 mm diameter. 2 cycles per pulse. 6 MHz, 2 mm diameter, 2 cycles per pulse.

62. Lateral resolution artifacts would be most profound with which of the following systems?. 10 MHz, 4 mm diameter, 4 cycles per pulse. 4 MHz, 4 mm diameter, 2 cycles per pulse. 7.5 MHz, 8 mm diameter. 2 cycles per pulse. 6 MHz, 2 mm diameter, 2 cycles per pulse.

63. The lateral resolution of 4 ultrasound machines are listed below. Which of the systems would produce the finest quality picture?. 2 cm. 4 mm. 6 mm. 8 hm.

64. Two small cysts are 2.4 mm apart. A line connecting the cysts is perpendicular to the main axis of an ultrasound beam. What will determine whether these structures will appear as two distinct images on the system's display?. the beam width. the pulse length. the PRF. the TGC.

65. In standard diagnostic imaging instrumentation, which has the higher numerical value?. longitudinal resolution. lateral resolution. neither, they have identical values.

66. What is the artifact known as acoustic speckle produced by?. accurate display of tiny reflectors. large reflectors in the medium. interference of tiny acoustic wavelets. resonance of particles in the near field.

67. What is true of acoustic speckle?. its effects are mild and it tends to slightly degrade images. it is a rare artifact that does not occur in real-time imaging. its effects are profound. nothing can be done to correct it.

68. What artifact results from an ultrasound beam having a finite and measurable three-dimensional profile?. acoustic speckle. multipath artifact. slice artifact. grating lobe artifact.

69. How does thickness artifact commonly express itself?. improper location of reflections. improper brightness of reflectors. absence of reflectors. strong linear echoes.

70. What is the artifact that results in improper side-by-side positioning of reflectors?. multipath. comet tail. refraction. reverberation.

71. What assumption is violated when the receiver processes a refracted acoustic wave?. waves travel directly to and from a reflector. sound travels at an average speed of 1.54 mm/us. sound travels in a straight line. the acoustic imaging plane is very thin.

72. Six distinct equally spaced reflections appear on an image at ever increasing depths. This scenario describes what type of artifact?. reverberation. ring down. mirror imaging. longitudinal resolution.

73. Which situation will commonly produce reverberation artifact?. two masses that lie perpendicular to the main axis of the sound beam. two weak reflectors that lie close to each other along the axis of the beam. two strong reflectors that lie close to each other along the axis of the beam. a single mass of highly reflective material.

74. Mirror imaging artifact is created by which of the following?. reflection. refraction. propagation speed error. attenuation.

75. The anatomic structure associated with a mirror image artifact is. sometimes shallower on the image than in the body. always deeper on the image than in the body. sometimes the same depth on the image as in the body. never deeper on the image than in the body.

76. What are the characteristics of a medium that produces comet tail artifact?. weak reflectors, closely spaced, low propagation speeds. strong reflectors, widely spaced, high propagation speeds. strong reflectors, closely spaced, low propagation speed. strong reflectors, closely spaced, high propagation speed.

77. What is a comet tail artifact's fundamental mechanism of formation?. reflection. rarefaction. refraction. redirection.

78. In general diagnostic imaging, what is the primary effect of multipath artifact on an image?. poor angular resolution. acoustic speckle. mild image degradation. gross horizontal misregistration.

79. Side lobe artifact is a result of which of the following?. sound beams bending. linear array transducer architecture. unexpectedly low acoustic attenuation. acoustic energy radiating in a direction other than the beam's main axis.

80. Side lobe artifact usually results in all of the following except ___________ . hollow structures appearing "filled in" on the image. reflectors not appearing on an image. reflectors appearing in improper locations on the image. reflectors appearing in multiple locations on the image.

81. Grating lobes are most common with which type of transducer technology?. annular array. continuous wave. mechanical scanners. linear arrays.

82. Grating lobes are produced by the same mechanism as which other artifact?. side lobes. reverberation. transaxial lobes. acoustic speckle.

83. True or False. Grating lobes are a result of substantial acoustic energy directed outward from a linear array transducer, but not along the main axis of the sound beam. True. False.

84. Which technique of linear array transducer design has virtually eliminated the appearance of grating lobe artifact on modern ultrasound systems?. demodulation. subdicing. deconvolution. none of the above.

85.True or False. Grating lobes are attributed only to linear array transducers. True. False.

86. Where do shadowing artifacts appear most commonly on an acoustic scan?. distal to a structure with a high impedance. proximal to a structure with a low propagation speed. distal to a structure with a high attenuation. next to a structure with a low elastance.

87. How is shadowing artifact expressed?. placing structures too deep on the image. placing structures in improper lateral position. placing reflections in multiple locations. reflectors being absent on the image.

88. Which of the following can produce shadowing?. refraction. attenuation. reflection. all of the above.

89. Unexpectedly low attenuation results in which of the artifacts listed below?. refraction. attenuation. enhancement. shadowing.

90. When enhancement occurs, where does it appear on the image?. in the near field. distal to a weak attenuator. in the far field. proximal to a weak reflector.

91. Acoustic focusing of an ultrasound beam may create which artifact?. side lobes. refraction. speckle. enhancement.

92. Which of the following artifacts occurs as sound travels through a medium with a propagation speed different from soft tissue?. vertical misregistration. horizontal misregistration. lateral resolution. ring down.

93. While imaging a test object, an ultrasound machine displays one image 1.8 cm deeper than another. Upon measuring the test object, it is found that one reflector is 2.0 cm farther that the other. What conclusion can be drawn from this?. The propagation speed of the test object is the same as soft tissue. The propagation speed of the test object is less than that of soft tissue. The attenuation of the test object is less than that of soft tissue. The propagation speed of soft tissue is less than that of the test object.

94. If an ultrasound pulse travels through a large cyst in the body at a speed of 1.2 mm/us, what happens to the position of all echoes produced from reflectors proximal to the cyst?. they are placed in too shallow a location on the image. they are placed in too deep a location on the image. they are likely to be placed at the correct depth.

95. If an ultrasound pulse travels through a large cyst at a speed of 1.2 mm/us, what happens to the position of all echoes produced from reflectors distal to the cyst?. they are placed in too shallow a location on the image. they are placed in too deep a location on the image. they are likely to be placed at the correct depth.

96. What is the most likely cause of ring down artifact?. refraction. inversion. reabsorption. resonance.

97. What type of artifact causes an ultrasound reflection to be placed at an incorrect depth?. lateral incertitude. shadowing. range ambiguity. indeterminate relaxation.

98. Which artifact is not affected by the shape or structure of an ultrasound pulse?. lateral resolution. slice thickness. mirror imaging. longitudinal resolution.

99. Which artifact is not related to the unexpected reflection of an acoustic wave?. multipath. comet tail. reverberation. lateral resolution.

100. True or False. All artifacts are errors in imaging that do not represent the true anatomy of the imaged organ. Therefore, they are all undesirable and should be eliminated if possible. True. False.