Exam 3 - ultrasound Flashcards
Linear array skin line appears
straight
Curved linear array, skin line appears
curved
Phased array is good for
putting in lines
best acustic window while viewing deeper structures
For best ultrasound view, you should
Use highest resolution (highest frequency) that still allows optimal viewing of anatomy desired
The 5 key points of image optimization in ultrasound
- Gel - seals for sound waves
- egronomics
- Ensure tranducer is flat and perpendicular to skin
- Aquire target at appropriate depth and in center screen
- Adjust gain to provide even contrast throughout the image
In short axis, transducer should be oriented
to patients right
In long axis, transducer should be oriented
to patient’s head
Optimal position for holding probe
at base like a pencil
Perpendicular is preferred over angled (probe position) except in
visualizing nerves
Ultrasound nerve visualization (depth and focal zone)
Depth: focus no more than 0.5 cm below target
Focal zone: 2-3 cm
goal of gain adjustment
contrast uniformity
gain MOA
amplifies returning echos
Doppler use
Identification of presence of blood flow
*especially important in protecting from inadvertent injection into blood vessel (especially above clavicle)
5 Transducer movements
- Sliding
- Tilting
- Rocking
- Rotating
- Compressing
Sliding use
ID of optimal block location
Rocking use
Correct air artifact
Tilting use
correct anisotrophy (artifact)
Anisotrphy definition and correction
Ultrasound beam is abosrbed d/t angulation of probe->structure
correct by tilting
Rotating
allows adjustment to scanning plane
Pressure/ Compression
decreases distance to target and helps target focal point
How to optimize image(acronym)
P.A.R.T
Pressure
Alignment
Rotating
Tilting
Rotation of probe is
fine tuning, hold like a pencil
Tilting allows for
perpendicular arrangement with underlying target, maximizes number of returning echos
Nerves in periphery appear as
honeycomb in cross section (not brachial plexus as much)
Tendons appear
similar to nerves, become flat and disappear when followed toward muscle belly
Vascular structures appear
anechoic circular structures in cross section (tubular in long view)
Adipose appears
Hypoechoic with streaks of irregular hyperechoic lines
Pluero/air apears
thin hyperchoic lines
lung is hyPOechoic with reverberation
Cysts appear
Similar to vascular, hypoechoic (black) in longtitudinal view
Bone appears
Hyperechoic (white) liner structure with shadowing underneath
Hypoechoic
black/grey
hyperechoic
white
anechoic
black
Muscle appearance
feather like in longtitudinal view
starry night in cross section
Attenuation is
shadowing (dark area beneath tissue) as intensity of sound wave decreases when it passes through tissue
Attenuation correction
adjust gain
Scattering appearance and cause
appearance: dark anechoic appearance
Cause: no sound waves returned (identifies fluid filled)
Air artifact cause and fix
cause: Transducer does not fully contact skin
fix: add gel and pressure, rocking
Reverberation aka
mirroring
reverberation- what is it and cause
sound wave bouncing back and forth
cause: strength of echo is decreasing resulting in what looks like multiple needles
To rule out plaque or or nerves in hyperchoic intima:
Turn transducer longtitudinally, get nerve scan
Specular reflection occurs on
long smooth surfaces
reflection is in singular direction
Diffuse reflection occurs on
uneven surfaces
reflection is multiple directions
Optimizing needle visualization - needle sould be
parallel to transducer
Optimizing needle visualization - at insertion site:
indent skin
Optimizing needle visualization: Transducer
Heeling of transducer
Optimizing needle tip other (2):
- hydrolocation (small amount of dextrose or local is injected into tissues
- Peripheral nerve stimulator
