Intro to Ultrasound and Knobology Cameron Jones, MD, MS Co-Chair - - PDF document

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Sep 03, 2023 266 likes •403 views

2/26/2014 Intro to Ultrasound and Knobology Cameron Jones, MD, MS Co-Chair for Emergency Ultrasound Kaiser Permenente, South Sacramento I have no disclosures 1 2/26/2014 SOUND : Series of pressure waves traveling through a medium

SLIDE 1

2/26/2014 1

Intro to Ultrasound and Knobology

Cameron Jones, MD, MS Co-Chair for Emergency Ultrasound Kaiser Permenente, South Sacramento

I have no disclosures

SLIDE 2

2/26/2014 2

SOUND: Series of pressure waves

traveling through a medium

Physics Words
WAVELENGTH:

Distance traveled in

ne cycle
FREQUENCY:

number of cycles per sec (Hertz)

“Fancy” Words

PIEZOELECTRIC EFFECT:

crystals vibrate at a given frequency when an alternating current is applied

PULSE-ECHO MODE: signal

generation <1% of pulse cycle

SLIDE 3

2/26/2014 3

ATTENUATION: Reduction of

intensity and amplitude

Absorption: Most common, creates heat
Reflection: “Echo”
Scattering: non-homogeneous surface
Refraction: Different densities

Ultrasound Modes

Brightness Mode: Different shades of gray

SLIDE 4

2/26/2014 4

Transducers (aka: Probes)

Increasing frequency improves resolution at the expense of penetration

Resolution: Ability to delineate

between 2 different objects

Axial Resolution:

The ability to separate

bjects linear to the

ultrasound beam

Lateral Resolution:

Ability to separate 2 structures side by side

SLIDE 5

2/26/2014 5

Transducer basics

Convex Array :

Sector Scanning - Resolution becomes poorer at greater depths

Transducer basics

Phased Array : Flat Head, crystals fire at variable time

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2/26/2014 6

Transducer basics

Linear Array

Echogenicity

Hyperechoic
More echogenic

than surrounding tissue

Object has lots of

echo’s, appears brighter

Hypoechoic
Less echogenic than

surrounding tissue

Very few echo’s,

appears darker

Anechoic / Echolucent
Absence of returning

echo’s

Area is black

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2/26/2014 7

Probe Position and Image Orientation

In relation to probe

dot

Transverse
Longitudinal
Coronal /

Sagittal

Button Basics

Gain
Strength of returning

echoes

Amplifier
Gain is adjusted

differently depending

n the machine

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2/26/2014 8

Artifacts:

Attenuation Artifacts

Shadowing
Partial or total

reflection of sound

Weak or no

transmission posterior

Artifacts:

Attenuation Artifacts

Posterior

Enhancement

Area behind echo-

weak or echo-free structure appears brighter

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2/26/2014 9

Artifacts:

Attenuation Artifacts

Edge Artifact aka

“Side Lobe”

Sound waves are

scattered when they encounter cystic wall

r curved surface
Energy loss
Reverberation
Sound encounters 2 highly reflective

layers

Sound is bounced back and forth
Probe detects a longer traveling time

Artifacts:

Propagation Artifacts

SLIDE 10

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Mirror Imaging
Sound glances off

highly reflective surface (diaphragm)

Returning sound

waves have longer travel time

Misinterpretation of

“more liver”

Artifacts:

Propagation Artifacts

Mirror Liver Diaphragm Mirror Liver Diaphragm

Artifacts:Mirror Image

SLIDE 11

2/26/2014 11 No Mirror Liver Diaphragm

Artifacts:Mirror Image

Trouble-Shooting

Know your anatomy

Define boundaries Choose the proper transducer Learn acoustic windows Go from wider view and zoom in Visualize the anatomy in two planes Maximize system controls - depth/gain/frequency

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Image Acquisition Tips

Use more gel!
Transducer movements
“I am having a hard time finding _____, do you have any

tips?”

Fan
Angle
Rotate
Translocate / Try a new location (window)

Only try one movement at a time