mahoney 6

Question 1

A mode

Answer 1

Sonar

• produced on an oscilloscope
• it measures HOW FAR the ECHO has traveled and how loud the echo is when it gets back
• uses a single transducer

Question 2

B-mode

Answer 2

• 2-D picture
• like A-mode, but ADDS DIRECTION, as well as deciphers all types of echoes, both strong and weak
• can recognize size and shape of object
• uses a lienar array of tranducers

Question 3

Doppler

Answer 3

• Measure blood flowing using doppler physics
  
  • Color doppler (BART)
    
    • BLUE signals indicates blood flow AWAY from probe
    • RED signals indicate blood flow TOWARDS the probe

Question 4

Role of the “notch”

Answer 4

• notch is placed on the PROXIMAL aspect of the structure during a LONGITUDINAL (long) scan
  
  • proximal aspect will be on the LEFT of the view screen
• The nothc is placed on the MEDIAL aspect of the structure when performing a TRANSVERSE (short) scan
  
  • medial aspec will be on the LEFT of the view

Question 5

relate frequency to penetration

Answer 5

• HIGH THE FREQUENCY WAVES PENETRATE LESS than lower frequency, but resolution INCREASES
  
  • resolution is the ability of ultrasound machine to distinguish two structures that are close together are separate.
• HIGH FREQUENCY TRANSDUCERS
  
  • improved resolution, decreased depth of penetration, used on superficial structures
• LOW FREQUENCY TRANSDUCERS
  
  • decreased resolution, full depth of penetration, best for abdominal and pelvic imaging

Question 6

attenuation

Answer 6

• the deeper the signal travels into the tissue, the more it is absorbed, and the weaker the signal that is reflected back from the tissue

Question 7

Impedeance def

Answer 7

• impedance is a property of a tissue defined as density of tissue and velocity of sound in that tissue
• air is low and bone is high

Question 8

hyperechoic, hypoechoic, anechoic definitions

Answer 8

• Hyperechoic = white = reflect majority of wave
• Hypoechoic = gray = reflect some of wave
• anechoic = black = reflect none of the wave

Question 9

structures that are hypechoic

Answer 9

• Bone, calcifications
• tendon (appear striated)
• fascia (appears non-striated)
• ligament
• air

Question 10

hypoechoic structures

Answer 10

• muscle (striated)
• nerve (look honeycomb)
• fat (with streaks of hyperechoic lines)
• articular cartilage

Question 11

anechoic structures

Answer 11

vessels

fluid (skin cyst, etc)

Question 12

define near zone

Answer 12

• the region of a sound beam in which the beam diameter decreases as the distance from the transducer increases
  
  • AREA NEAREST TO THE TRANSDUCER

Question 13

Fat zone

Answer 13

• region of a sound beam in which the beam diameter increases as the distance from the transducer increases
  
  • area furthest from transducer

Question 14

define anistropy

Answer 14

ultrasound artifacts

• occurs when the beam is not DIRECTLY PERPENDICULAR to fibrillar tissue (tendon, ligament, fascia) being examined
• instead of looking HYPERECHOIC, the structure becomes more HYPOECHOIC as the angle increases
  
  • because less ultrasound refleced, so image is darker

Question 15

define shadowing

Answer 15

artifact

• ultrasound beam is reflected, resorbed, or refracted from bone or calcified object
• ACOUSTIC SHADOWING
  
  • false anechoic area (dark shadow) below the reflective surface (beneath bone for example)
• EDGE SHADOWING
  
  • dark shadow behind the edge of spherical structures when beam reflects off rounded surface

Question 16

posterior acoustic enhacement def

Answer 16

artifact

• occurs during imaging of fluid
• DEEP TO A FLUID COLLECTION, the soft tissue will appear relatively hyperechoic compared with the adjacent soft tissue

Question 17

posterior reverberation

Answer 17

• occurs when surface of object is smooth and flat (metal foreign body or surface of bone)
• beam reflects back and forth between the surface and transducer producign a series of linear reflective echoes that extend deep to the strucure

Question 18

gain knob

Answer 18

controls overall brightness of the image

• excessive/inadequate gain causes blurring tissues and tissue boundaries leading to inaccurate info

Question 19

time gain compensation (TGC)

Answer 19

allows adjustment of image brightness at selective depth

• increases the amplification of echoes from increasing tissue depths
• it is used to correct for increased attenuation of sound with tissue depth

Question 20

depth knob

Answer 20

allows adjustment of the depth of field of view

• as depth increases, width of image gets narrow
• MEASURED IN CM

Question 21

focus knob

Answer 21

allows focus of ultrasound beam to area of interest

Question 22

frequency knob

Answer 22

adjustment frequency to balance depth and resolution needs

• measured in MHz
  
  • probe type is critical for frequcny = LIMITING AGENT

Question 23

sweep motion

Answer 23

move entire probe perpendicular to the length of the probe (like a broom

Question 24

slide motion

Answer 24

move entire probe in line with the length of the probe

Question 25

rock/tilting motion

Answer 25

with the probe kept on one spot, tilt the probe along its long axis (like the leg of a rocking chair)

Question 26

fan motion

Answer 26

with the probe kept on one spot, tilt the probe along tis short axis (like a fan)

Question 27

rotate motion

Answer 27

* rotate position of probe to align with anatomy (like hands on a clock)