Richard Palma, BS, ACS, RCCS, RCS, RDCS Duke University

1. Technical Considerations
Using POCUS
Richard A. Palma
BS, ACS, RCCS,RCS, RDCS, FACVP,
FSDMS, FASE
Director and Clinical Coordinator
Duke School of Cardiac Ultrasound

2. • Lantheus medical Imaging: Speakers Bureau
• Philips Medical Imaging Speaker Bureau
• ESP Speaker Bureau (Physics)
Disclosures:
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©2017 Trinity Health Of New England

3. Technical Difficulties Include
• Imaging through bone, air, and dense
tissues. leading to poor visualization
• Patient factors such as high body mass
index (BMI) and surgical dressings can
hinder image quality and window access
• POCUS devices may also have poor
battery life, lower image resolution
• Ergonomic challenges compared to larger
systems

4. Temporal Resolution
Ability to accurately display events in real-time
Rule - All the ultrasound from any given pulse must return to
the transducer before the next pulse.
Temporal resolution can be appreciated by observing the
Frame Rate
CARDIAC IMAGING IS ALL ABOUT THE FRAME RATE

5. Difficult to appreciate cardiac motion
with slow frame rate

6. Higher frame rate Lower frame rate
shallow deep
single focus multi focus ( lat res)
narrow sector wide sector
low line density hi line d’sity ( spat’l res)
SUMMARY - TEMPORAL RESOLUTION

7. Types of Resolution
•Axial Resolution
•(SPL)
•Lateral
(Beam Width)
•Elevational
•(Slice Thickness)

8. HIGH FREQUENCY SOUND
• Creates short pulses
• Creates less divergent beams
• High frequency sound improves both axial
resolution (everywhere) &
lateral resolution (in the far field only)

9. CLINICAL COMPROMISE
• Higher frequencies provide better image
detail
• Lower frequencies penetrate deeper

10. Attenuation
• Much, much higher in air than in soft
tissue
• Higher in
bone due to absorption
lung due to scattering
• much lower in water than soft tissue
Sound interaction with the body

11. Dr. Joseph Kisslo’s Rules of Echo
1.) If you don’t point at it,
you won’t see it
2.) If you don’t see it, you
can’t diagnosis it
3.) It’s not the heart
stupid !

12. Artifacts
Occurs due to many assumptions
•The transmitted and received waves travels in a
straight path
•The echoes return to the transducer after a single
reflection
•Echoes originate from the main beam
•The sound wave travels at a constant 1540 m/sec
•Pulses and echoes are attenuated uniformly by all
tissues (0.5 dB/cm/MHz)

13. Ultrasound Assumption Violations
Another way to think about these
Axial Direction
Artifacts located
below the real
Structure
Lateral Direction
Artifacts located to the side
of the real Structure
1.Reverberations
2.Mirror Image
Artifacts
3.Acoustical shadowing
or enhancement
1.Beam Width Artifacts
2.Side Lobe Artifacts
3.Refraction Artifacts

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Shadowing Artifact

15. Reverberation Artifact

17. Refraction Artifact

18. Mirror Artifact
Bertrand et al, JASE Volume 29 Number 5
(onlinejase.com video 4)

19. Side Lobe Artifact

20. Receiver Gain (Kills Resolution)
• Goal
– Correct brightness
– Homogenous
– Level that does not eliminate valid signals or over accentuate what is
there
– Use TGCs to even out image gain throughout the sector
High Gain Low Gain Correct Gain

21. Thank You! Questions?
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©2017 Trinity Health Of New England