Apex- Ultrasound Flashcards
How fast does ultrasound propagate through soft tissue?
A. 343m/sec
B. 1540m/sec
C. 3051m/sec
D. 4892 m/sec
B. 1540m/sec
WHO FUCKING CARES
air = 343m/sec
bone = 3k-5km/sec
Higher frequencies produce (shorter/longer) wavelengths
Lower frequencies produce (shorter/longer) wavelengths
higher frequencies = shorter wavelengths
lower frequencies = longer wavelengths
Match compression and rarefacation with
high pressure vs low pressure
high pressure = compression
lower pressure = rarefaction
T/F: frequency is a measure of pitch
how is it expressed
true
in Hertz (Hz) or cycles per second
what represents a sounds loudness and is measured in decibels
amplitude
What is sound?
a pressure wave that travels in a longitudinal wave.
A sound wave is created when a vibrating object sets the molecules of a medium into motion
Which concept BEST explains why lead zirconate titanate is commonly used in ultrasound transducers?
A. Echolocation
B. Doppler Effect
C. Snell’s law
D. Piezoelectric effect
D. Piezoelectric effect
To produce an image, the ultrasound transducer utilizes a piezoelectric material that can transduce electrical energy into a mechanical (sound) energy and vice versa.
Echolocation describes the use of sounds and echos to determine where objects are located in space
how does the ultrasound machine produce a visual image?
by using a piezoelectric material that transduces electrical energy to mechanical (sound) energy.
by applying electric current to a piezoelectric material, it will vibrate and emit sound waves; conversely, if you subject that material to sound waves (ie mechanical stress), that material will generate an electrical potential
what is a common piezoelectric material commonly used in ultrasound transducers?
lead zirconate titanate
What is the primary determinant of the vertical placement of each illuminated pixel on the u/s monitor?
A. Time delay
B. Resolution
C. Acoustic impedance
D. Doppler effect
A. Time delay
What determines the vertial placement of each dot on the screen?
how long it takes for the echo to return to the transducer (time delay)
What determines the horizontal placdement of each dot on the screen?
the particular crystal that receives the returning echo
Match each term with its BEST descriptor: hyperechoic, hypoechoic, anechoic
-produces high amplitude echos
appear as dark shades of grey
does not produce echos
produces high amplitude echos → hyperechoic
appear as dark shades of grey → hypoechoic
does not produce echos → anechoic
T/F: hyperechoic structures appear **bright **and produce strong, **high-amplitude echoes. **
True
How do vascular structures appear in short axis vs long axis
short axis = black/anechoic circles
long axis = black/anechoic tubes
How does bone appear on u/s
do these have a high or low impedence?
hyperechoic - white
strong/high amplitude echos produced
high (3k-5k)
4 examples of hypoechoic structures
do they produce high/low amplitude echoes
do they have high/low impedence
solid organs (liver)
skin
apidose
cartlidge
lower amplitude
lower impedence
How does muscle appear on u/s
hypoechoic with hyperechoic fasical lines
3 examples of anechoic structures
Vascular structures
Cysts
Ascities
what should a distended, non-compressible vein raise suspicion for?
DVT
T/F: nerves can appear anechoic or hyperechoic depending on the region of the body
True
-peripheral nerves near the neuraxis tend to apppear anechoic (traffic lights)
-distal peripheral nerves are hyperechoic (white) with a characteriestic honeycomb appearance
are peripheral nerves that are distal or near the neuraxis the ones that are hyperechoic with a honeycomb appearance
distal peripheral
peripheral near the neuraxis are anechoic
t/f: peripheral nerves are collapsible but non-pulsatile
false- they are not collapsible or pulsatile
T/F: the best method to differentiate a tendon from an erve is by scanning distal from the muscle towards the joint
false - scan proximal from the joint towards the muscle
tendons become flat and disappear as they connect to muscle ; they also appear “rope-like” at joints where they connect to bone
nerves are continuous and will not change size as you scan
T/F: nerves are continous and will not change in size as you scan
True
tendons become flat and disappear as they connect to muscle ; they also appear “rope-like” at joints where they connect to bone
What process describes a sound wave that bounces off a tissue boundary that has a different acoustic impedance?
a. Absorption
B. Reflection
C. Scatter
D. Refraction
B. Reflection
Absorption occurs as u/s waves are lost to body as heat
Scatter occurs when u/s wave encounters an object smaller than the wave
Refraction = bending of the ultrasound wave that encounters a tissue boundary at an oblique angle
**T/F: Resolution is the ability to see two seperate things as two seperate things
True
T/F: the focal zone is the region where the beam is the narrowest
True
What is the Frensel zone vs Fraunhofer zone?
Frensel zone = near zone (region b/t transducer and focal zone)
Fraunhofer zone = far zone (region beyond the focal zone
Fraunhofer = longer = further out
Short axis vs long access and how they look at structures
short axis - looks at a structure in cross-section
long axis - looks at a structure along its length
Match terms: Axial, lateral, elevational
-beam thickness
-beam depth
-beam width
-beam thickness : elevational
-beam depth : axial
-beam width : lateral
order the structures that produce the degree of attenuation they provide from greatest to least : soft tissue, bone, fluid
Bone (greatest) - furtherst , weakest image
Soft tissue
Fluid
Is attenuation a greater threat to higher frequency sound waves or lower?
higher
Applying gel b/t transducer and pts skin reduces:
A. Absorption
B. Reflection
C. Scatter
D. Refraction
B. Reflection
T/F: Scatter explains why fluid- filled structures appear anechoic
True
Scatter occurs when the u/s wave encounters an object smaller than the wave
>this causes the echoes to scatter in all directions, so the signal never returns to the transducer
What describes the bending of an ultrasound wave that encounters a tissue boundary at an oblique angle?
What law?
Refraction
Snell’s law
a formula used to calculate the refraction of light when passing b/t two media with different refraactive indices
Match the following : Axial, Elevation, Lateral
The ability to differentiate structures that are:
-side-by-side in the x-axis
-in the same plane of the ultrasound beam in the y-axis
-are in the thicness of hte ultrasound beam in the z-axis
Lateral → side-by-side in the** x-axis (horizontal)**
Axial → in the same plane of the ultrasound beam in the y-axis (vertical)
**Elevation **→ are in the thicness of hte ultrasound beam in the z-axis (depth)
Which type of transducer produces the BEST image resolution?
A. High frequency
B. Medium frequency
C. Low frequency
D. Ultra-low frequency
A. High frequency
Low frequencies = longer wavelengths - allow us to see deeper but we sacrifice resolution
high frequency = shoter weavelengths - cant see as far but have better resolution
Transducer selection: > 10Hz, 5-10Hz, <5 Hz :
Axillary block
> 10
High frequency
shorter wavelengths
high resolution
linear array transducer
What’s the isssue here
too much gain
Issue? How to fix it
not enough gain - increase the gain
which is “in-plane” vs “out- of - plane”
first = in-plane (long-axis)
second = out-of-plane (short axis)
label from left to right, top to bottom
- tilting
- rocking
- sliding
- compression
- rotating
D. Reverbation
occurs when a sound wave bounces b/t 2 strong parallel reflecting surfaces
-you could observe this while imaging the pleura or when using a highly attenuating wide-bore nedle (shown in the image)
what kind of artifact
bayoneting
-occurs as needle passes thru adjacent tissues of different acoustic impedence
What are the 3 standard imaging windows for the cardiac POCUS
Parasternal, Apical, Subcostal
label
how should hte pt be positoned?
transducer placement
markerorientation
left lat decub or supine
phased-array tarnsducer just left of the sternum at the 3rd or 4th intercostal space
orient marker twoards pts right shoulder
how to establish this view
get a PLAX view (left lat debup or supine) & rotate trandsucer 90 dgrees clockwise
so orientation maker points towards pts left shoulder
label
position and orientation of marker
left lat decub, transducer on the PMI
-orient transucer to pts left side with beam pointing towards right shoulder
label
transducer placement:
orientation:
inferior to xiphoid process
marker towards pts left side
*might have to apply a good amount of pressure - discomfort
-have pt bend knees up to relax abd
label
how to get ur view
from a subcostal 4-chamber view (inferior to xiphoid), rotate transducer 90 degrees and tilt the beam in a posterior diretion
label this parasternal long axis us image
RV
LV → Aorta
Pericardium → LA
Descendig aorta
label parasternal short axis image
RV→Intraventricular septum →LV
label this subcostal 4 chamber image
top = liver
bottom up going left to right
RA → RV
LA →LV
label subcostal ivc image
RA → Liver → IVC
What’s dat
Gastric antrum
lowest part of the stomach
-used to determine if pt has a full stomach
label
Empy stomach, clear fluids or particulate matter
Empty stomach = bulls eye
anechoic border isn’t fluid, its the muscularis propriae
clear liquids = anechoic
contents will make antrum look round and distended
What best describes the color of the interneal jugular vein
positive doppler shift
-the angle of isonation relative to the IJ flow is less than 90 degrees, appearing on the screen as a red color, repreenting a postive doppler shift
Low frequency → spinal block
Medium → Sciatic
High → interscalene
Anechoic → Cyst
Hypoechoic → Liver
Hyperechoic→ Thyroid cartilage
