ultrasound Flashcards
How does an ultrasound work
high freq sound waves
bounced off internal aging of organs and tissues
waves produced by, and reflected back to, transducers to form 2D images
transducer measures how long it takes to get back
called B mode or 2d mode
Low resolution probe
3.5mHz transducer
low resolution but increased depth of view
curved array - untrasound path around the ribs
can see the kidney, liver and diaphragm
high resolution probe
limited depth of view
see things close to the body surface eg surface of lung
probe has flat surface and straight edge
7-12mHz
use of high frequency probe
detect pleural effusion
pneumothorax
normal anatomy of lung in high resolution US
see the skin
the parietal and visceral pleura - echogenic line - straight with some irregularity (normal)
can see the visceral pleura sliding back and forth - gliding pleura/sliding lung sign
parietal pleura - stationary
nothing between the chest wall and the lung
Reasons for breathlessness that you would see on an US
pneumothorax
pneumonia
pleural effusion
Reverberation artefacts
normal
show the lung is air filled
parallel to lung age
echos of lines at the surface - some sound waves go into the lung before they hit the transducers o look like hit something else
why would you scan across the ribs
when have a large pt
white line from rib - all US reflected back - black shadow behind
so you can be sure white line behind the rib is the lung
Comet tail or B line artefact
expect 1 or 2 normally
perpendicular to the lung edge
from the interlobular septa up to the lung surface
comet tail artefact in pul oedema
distended with fluid
enlarged so see more than normal
M mode US
1d display
of motion and echo-producing interfaces displayed against time along the 2nd axis
beam of US dropped through 1 point
see how everything moves under that area
best way to diagnose pneumothorax
M mode normal lung
sea shore sign
see elongated picture
skin and muscle don’t move - so straight line
white line from the pleura
granular image behind this - moving artefacts
Planes of CT
axial - give X sectional image through liver
longitudinal coronal plane - ribs in way, caudal on the R of the picture cranial on L of picture
paracoronal/parasagittal - between ribs - v good for seeing the lung
longitudinal sagittal plane - cranial = L, caudal = R, see skin, liver, aorta, vertebral bodies
Use of US of the thorax
detect pleural effusion and drain it
differentiate sub-pul from sub-phrenic fluid
assess tumour invasion of chest wall and pleura
guide pleural and lung biopsy
identification of pneumothorax
assessment of resp lung func
pul effusion on US
tiny bit = normal
small pleural effusion = still artefact = lung still full of air
pul effusion seen as black between the lung and the chest wall
large pul effusion = lung looks solid = alveoli compressed, see heart (LV and descending thoracic aorta) because fluid transmits US easily
