Ultrasound Flashcards
What is POCUS
Point of care US: done at bedside to guide the treatment of the patient.
POCUS is done to answer a specific question. like what?
is there an effusion
is there gallstones
is there hydronephrosis
How does POCUS benefit patients and docs?
improves diagnositc accuracy, while bringing doc to bedside
What are advantages of POCUS?
- No ionizing radiation
- noninvasive
- protable
- easy and FAST
- immediate feedback
- not expensive
- easily repeated, so enhances docs ability to perform serial reassessment
What are disadvangtes of POCUS?
1. operator dependent
2. Poor image quality with fat and or air
what is the physics of a US probe?
- US has crystals like quartz.
- Electrical current causes crystals to vibrate => produce sound/pressure waves
- Waves travel and hit object
- Some waves are reflexted back to probe
- Sound waves hit => create electrical current => converted to image.
_____ (Hz) is the number of times/second a wave is generated
frequncy
_____ is the distance the wave travels in a single cycle
wavelength
how is wavelength & frequency related?
inversely; high frequency = shorter wavelength
What type of sounds penetrate more deeply into tissue?
- High frequency/shorter wavelenth
- Low frequency/ longer wavelength
Low frequency/ longer wavelength
What kind of probes are best for deep tissue, used to see abdominal structures (aorta, kidney, gallbladder?
What is a downside to this?
Low frequency probes
Bad resolution
What kind of probes are best for superficial things (BV, breast tissue and thyroid tissue)
What is a downside to this?
High frequency probes
Poor penetration but GOOD resolution
Name the 3 different types of probes.
- Linear (vascular) probe
- 2. Sector or phased array (cardiac) probe
- Curvilinear (curved array or abdominal) probe
Linear probe (vascular)
- _________ frequency and resolution
- Used for:
- Pros:
- Higher
- Superficial scanning & procedural guidance
- Lateral resolution is preserved
Sector or phased array probe (cardiac)
_________ frequency
Used for:
Pros:
- Lower
- Intercostal scanning bc it has a small footprint
- High frame rates
Curvilinear (cuved array or abdominal) probe
_________ frequency
Used for:
Pros:
- Lower frequency
- abdominal
- Large field of view and large footprint
US is best for ID’ing what?
- kidneys
- liver
- spleen
Besides kidneys, liver and spleen, US can also be used to ID:
heart
aorta
IVC
Bladder
Morrisons pouch is on the ____ flank and is a _____ view
Right flank
Hepatorenal view
FAST (Focused assessment with sonography for trauma) is used as what?
Quick screening test for trauma patients to detect [intraperitoneal/pericardial/pleural fluid, hemothorax, pneumothorax].
IF we find nothing on FAST scan, does that rule out intrabdominal injury?
NOO; has limited sensitivity
Where is morrisons pouch located?
whats structures does it include
RUQ at the edge of the lower lateral thoracic cage.
includes: liver, kidney and diapragm
Perisplenic view is located on _____
L flank
the ability of a structure to reflect sound waves or echoes
echogenicity
Structure does not reflect sound waves and appears black (fluid)
Anechoic
Structure reflects very few echoes and appear darker than surrounding tissue
hypoechoic
echogenic structure; appears brigher than surrounding tissue
hyperechoic
common artifact that occurs when the sound waves encounter a highly reflective surface
acoustic shadowing
what appears deep to highly reflective surface that undergoes acoustic shadowing?
Hypoechoic or anechoic area
Why are structures deep to highly reflective surfaces in acostic shadowing hypoechoic or anechoic?
Give an example
sound waves cannot get behind or around structure
gall stones
What is posterior acoustic enhancement?
give an example
- articfact that occurs when a structure behind an anechoic structure appears very ecogenic/bright because little sound waves are lost traveling though fluid filled structure
- Ex. Bladder.
What is edge artifact?
- Sound that is bent by a structure in parallel with a US beam and does not return to the probe, creating a shadow behind the surface.
When is an edge artifact usually seen?
- fluid fileld structures (GB)
- vessels in transverse imaging
what is a mirror artififact
- mirror image of highly refective strucure that is distal to the probe
- appears bottom or periphery of screen
Reverbaration artifact is typically seen with ________ and looks like what?
line placement
mutuple intermittant echoes that run parallel to needle.
What are the 4 cardinal probe movements?
- 1. Sliding: slide along skin w/o changing angle
- 2. Rocking/heel-toe: tilt along indicator
- 3. Fanning/sweeping: tilt perpendicular to axis of indicator
- 4. Rotating or twisting: rotate about axis, w/o tilting
Diagnostic US has never been shown to harm humans and safe for fetal imaging at all gestational ages.
Even then, what do we practice?
ALARA (as low as resonably acheivable) exposure to US in ANY given test
Where is the probe marker oriented with longitudinal scanning?
What about transverse scanning?
- to the head
- to the patients right, so image will look similar to CT.
- EXCEPT cardiac, marker is on the left
what happens if you flip the probe
flip orientation of screen
where does the concept of ALARA come from?
use of ionizing radition in CXRs
