Set 1

Question 1

Propagation speed of ultrasound in the following tissues:
1. Fat:
2. Soft tissue (average):
3. Muscle:
4. Cartilage:
5. Tendon:
6. Bone:

Answer 1

1. 1450 m/s
2. 1540 m/s
3. 1580 m/s
4. 1660 m/s
5. 1750 m/s
6. 3500 m/s

Question 2

Sound wave parameter that describes the time required for the sound wave to complete 1 cycle:

Answer 2

• Period
• Typical value 0.06 to 0.5 microseconds

Question 3

Sound wave parameter that describes the number of cycles that occur in 1 second:

Answer 3

• Frequency
• Typical value 2 to 15 MHz
• Inversely related to period

Question 4

Sound wave parameter that describes the length of a single cycle:

Answer 4

• Wavelength
• Typical value 0.1-0.8 mm
• Inversely related to frequency

Question 5

Sound wave parameter that describes how fast sound travels in a medium:

Answer 5

• Propagation speed
• Average value in soft tissue 1540m/s
• Directly related to stiffness of tissue
• Inversely related to density of tissue

Question 6

Frequency range for…

• Infrasound:
• Audible sound:
• Ultrasound:

Answer 6

• Infrasound <20KHz
• Audible sound 20 to 20KHz
• Ultrasound >20KHz
  
  • Frequency range typically used for diagnostic ultrasound is 1-20MHz

Question 7

Describe attenuation of ultrasound wave:

Answer 7

• Defined as the weakening of the sound wave energy as it travels through a medium
• Limits the depth of imaging
• Directly related to frequency (higher frequency results in greater attenuation)

Question 8

Describe the clinical rule for choosing frequency:

Answer 8

Use the highest frequency that allows the area of interest to be displayed

Question 9

Describe the pros and cons of a high frequency probe:

Answer 9

• Pros: better resolution and image detail
• Cons: greater attenuation (less penetration)

Question 10

Describe the pros and cons of a low frequency probe:

Answer 10

• Pros: less attenuation (greater penetration)
• Cons: worse resolution and image detail

Question 11

According to the ALARA principle, to optimize an image that is…

• too bright:
• too dark:

Answer 11

• Too bright: decrease output power
• Too dark: increase receiver gain

Question 12

Artifact caused by imaging a specular reflector (tendon) at an oblique angle causing the structure to appear less echogenic than normal:

Answer 12

• Anisotropy
• Can be misinterpreted as pathology
• Correct by imaging perpendicular to structure

Question 13

Artifact indicated by #2 in this split screen image of the FPL tendon:

Answer 13

Anisotropy results from imaging a brightly reflective (specular reflector) at an oblique angle (as shown in #2). To correct this artifact reposition the probe so that the beam angle is perpendicular to the structure (as shown in #1).

Question 14

List the order of susceptibly of MSK tissues to anisotropy:

Answer 14

Tendon > Ligament > Nerve > Muscle

Question 15

Artifact that results when the US beam hits a tissue interface with a very large impedance difference causing all of the US energy to be reflected:

Answer 15

Posterior acoustic shadow

Question 16

Artifact indicated by the arrow:

Answer 16

Posterior acoustic shadow

Question 17

Artifact that results when the beam passes through tissue (fluid) with low attenuation causing the deeper tissue to appear more echogenic than normal:

Answer 17

Posterior acoustic enhancement

Question 18

Artifact indicated by the arrow:

Answer 18

Posterior acoustic enhancement

Question 19

Artifact that occurs around highly reflective curved surfaces (tendon) that results in sound energy being defected away from the probe; results in shadow forming deep curved area:

Answer 19

Refractive edge shadow

Question 20

Artifact indicated by the arrows:

Answer 20

Refractive edge shadow