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3/29/2016 1

Critical Ultrasound for Patient Care

April 6-8, 2016 Sonoma, CA

UC SF

University of California San Francisco

Critical Ultrasound for Patient Care

April 6-8, 2016 Sonoma, CA

UC SF

University of California San Francisco

I have nothing to disclose I have nothing to disclose Intro to Ultrasound and Knobology

Cameron Jones, MD, MS Co-Director of Emergency Ultrasound Kaiser Permenente, South Sacramento

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SOUND: Series of pressure waves

traveling through a medium

• Physics Words
• WAVELENGT

H: Distance traveled

in one cycle

• FREQUENCY:

number of cycles per sec (Hertz)

What is “ULTRASOUND”

Diagnostic US: 2.5-14 MHz

ALARA

“As low as reasonably achievable”

• No confirmed

biological effects

• n patients or
• perators have

been reported

• Intensities typical
• f diagnostic

ultrasound

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Cocktail Party Words

• PIEZOELECTRIC EFFECT:

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

How it works How it works

• Echo’s have discrete

amplitudes and are thus assigned a specific “brightness” and location on the screen

• Screen location of

“brightness”/echo depends

• n time wave took to return

and direction it returned from

Pulsed Wave Output

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Ultrasound Modes

B-mode Brightness Mode: Different shades of gray

Motion Mode

Displays returning echo’s along one line of B-mode over time

Color Doppler

The doppler shift

Direction and velocity are color-coded and projected on the B-mode image

Power Doppler

Does NOT examine flow velocity or direction of flow

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Pulsed Wave Doppler

Displays “spectrum” of returned doppler frequencies

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

Resolution

Lateral Resolution:

Ability to separate 2 structures side by side

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Transducer basics

Convex Array :

Sector Scanning - Resolution becomes poorer at greater depths

Transducer basics

Phased Array : Flat Head, crystals fire at variable time

Transducer basics

Linear Array

Transducer Indicator

“Probe Dot”

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Learning the language

It just takes time...

Echogenicity

• Hyperechoic
• More echogenic

than surrounding tissue

• Object has lots of

echo’s, appears brighter

Echogenicity

• Hypoechoic
• Less echogenic

than surrounding tissue

• Very few echo’s,

appears darker

Echogenicity

• Anechoic /

Echolucent

• Absence of

returning echo’s

• Area is black

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Probe Position and Image Orientation

• In relation to probe

dot

• Transverse
• Longitudinal
• Coronal /

Sagittal

Image Orientation

Longitudinal Transverse

Longitudinal

Head Foot Right

Left

Transverse

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Coronal

(Longitudinal)

Button Basics

• Shallower
• Deeper

Depth Button Basics - Depth Button Basics - Depth

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Button Basics - Depth Button Basics

• Gain
• Strength of returning

echoes

• Amplifier
• Gain is adjusted

differently depending

• n the machine

Goldilocks and the 3 Bears

Top overgained, Bottom undergained Bottom overgained, Top undergained

Goldilocks and the 3 Bears

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Entire field overgained

Goldilocks and the 3 Bears

Entire field undergained

Goldilocks and the 3 Bears

Perfect gain top to bottom

Goldilocks and the 3 Bears

Make Gain Uniform

• “I have messed

around with the gain knobs, and now I can’t see anything...”

• AUTO GAIN

Gain “What if I get lost?”

AUTO GAIN

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ATTENUATION: Reduction of

intensity and amplitude

• Absorption: Most common, creates heat
• Reflection: “Echo”

ATTENUATION: Reduction of

intensity and amplitude

• Scattering: non-homogeneous surface
• Refraction: Different densities

Artifacts:

Attenuation Artifacts

• Shadowing
• Partial or total

reflection of sound

• Weak or no

transmission posterior

Artifacts:

Attenuation Artifacts

• Shadowing
• High attenuating tissue leaves an acoustic shadow

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Artifacts:

Attenuation Artifacts

• Posterior

Enhancement

• Area behind echo-

weak or echo-free structure appears brighter

Artifacts:

Attenuation Artifacts

• Posterior

Enhancement

• Echoes enhanced

posteriorly behind low attenuating tissue

Artifacts:

Attenuation Artifacts

• Posterior

Enhancement

• Echoes enhanced

posteriorly behind low attenuating tissue

• Adjust gain to view a

clearer image

Artifacts:

Attenuation Artifacts

• Edge Artifact aka

“Side Lobe”

• Sound waves are

scattered when they encounter cystic wall

• r curved surface
• Energy loss

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Artifacts:

Attenuation Artifacts

• Edge Artifact
• Reverberation
• Sound encounters 2 highly reflective

layers

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

Artifacts:

Propagation Artifacts

• Reverberation
• Recurrent bright arcs at equidistant intervals

Artifacts:

Propagation Artifacts

• Comet Tail
• Narrowly spaced

reverb

• very strong

reflector

Artifacts:

Propagation Artifacts

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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

Mirror Liver Diaphragm

Liver

Artifacts:

Propagation Artifacts

• Mirror Imaging

Artifacts:

Mirror Image

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No Mirror Liver Diaphragm

Artifacts:

Mirror Image

No Mirror

Liver Diaphragm

Liver

Artifacts:

Propagation Artifacts

• Mirror Imaging

Artifacts:

Mirror Imaging

Trouble-Shooting

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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

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

Historical Perspective

• “Like most new technology, there is a risk that new practitioners

will make mistakes based on their erroneous interpretations”

• “This technology, therefore,

MUST BE RESTRICTED”

1832 editorial

Why Ultrasound? 1946 2010

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Why Ultrasound?

• 1962 - First B-mode scanner

2012

Where will we be in 2062?

Questions?