Ultrasound

Question 1

advantages of US

Answer 1

-non invasive and painless
-no ionizing radiation- no known harmful effects
-performed in office at bedside - extremely portable
-less expensive than CT or MRI
-images viewed in real time
-real time video recording of study can be made

Question 2

disadvantages of US

Answer 2

-obesity may affect study quality
-movement causes artifacts
-overlying air obstructs visualization of structures
-sonogram waves do not penetrate bony structures
-difficult for US waves to penetrate intra abdominal fat -> affects image quality

Question 3

dx US

Answer 3

-non invasive imaging technique using high frequency sound waves (>20)
-transducer (probe)- emits and receives sound waves from various tissues in body

Question 4

US physics

Answer 4

-piezoelectric effect:
-electric field is applied to an array of piezoelectric crystals located on the transducer surface
-electrical stimulation causes mechanical distortion of the crystals resulting in vibration and production of sound waves
-sound waves projected through skin
-transducer is placed against patients skin with thin layer of gel to displace air that would deflect US beams
-high frequency sound waves directed at internal body structures
-gel allows clear image to be produced
-as sound waves travel into pt, wave fronts spread out diminshing beam intensity
-NOT ON TEST

Question 5

US terminology

Answer 5

-hyperechoic- more echogenic than surrounding tissue (more sound waves)
-objects appear brighter, has MORE reflected US waves

-hypoechoic- less echogenic than surrounding tissue
-objects appear darker -> has FEWER reflected US waves

-anechoic/echolucent- absence of returning sound waves -> area is black

-fluid is an excellent conduct of sound waves -> hence fluid will always appear black

Question 6

US findings

Answer 6

-strong echoes are close to white
-weak echoes are closer to black
-fluid is black
-fat is white
-muscle is grey
-solid organs appear echogenic (grey)
-since sound waves travel well through fluid, cysts or fluid appear echo free or anechoic (black)
-fluid in bladder improves visualization by enhancing movement of soundwaves across abd cavity

Question 7

US limitations

Answer 7

-sound waves DO NOT penetrate gas or bone
-air is enemy of US:
-sound waves conduct poorly through air
-in air, sound waves have nothing to reflect against
-produces blurred, indistinct images that cannot be interpreted

Question 8

air artifact

Answer 8

-lack of conduct gel
-subcutaneous emphysema
-gangrene

Question 9

artery vs vein

Answer 9

-probe on vein -> collapse
-probe on artery -> bounce back

Question 10

bone artifact

Answer 10

-bone surface reflects all sound waves
-all structures below bone are obliterated
-known as shadowing

Question 11

US artifact findings: posterior enhancement

Answer 11

-area behind echo, weak or echo free structure appears brighter
-beam remains strong as it passes through fluid as opposed to surrounding structures

Question 12

edge artifact

Answer 12

-AKA side lobe
-sound waves are scattered when they encounter a curved surface
-energy loss on reconstruction appears as more echolucent

Question 13

resolution

Answer 13

-ability to delineate between 2 diff objects
-axial resolution- ability to separate objects linear to US beam
-lateral resolution- ability to separate 2 structures side by side
-increasing frequency improves resolution at the expense of penetration

Question 14

US probes

Answer 14

-different size and shapes for different studies
-linear probe (5-10)
-curvilinear probe (3.5-5)
-phased array (cardiac) probe
-obstetrical probe

Question 15

ala cart for systems

Answer 15

-cardiac
-vascular
-thoracic
-abdominal
-OBGYN
-testicular and prostate
-thyroid
-ocular
-musculoskeletal
-neuro (nerve blocks)
-TEE

Question 16

linear probe

Answer 16

-5-10 high frequency for structures near body surface
-vascular imaging
-central line placement
-eval for pneumothorax

Question 17

curvilinear probe

Answer 17

-sinks into abdomen
-low frequency allowing deep penetration and wide depth of field
-for intra abdominal structures

Question 18

phased array (cardiac) probe

Answer 18

-2-4
-large depth of field with small footprint
-good for viewing structures in the chest

Question 19

obstetrical probe

Answer 19

-5-10
-used for trans-vaginal exam
-visualizing uterus, ovaries, cervix
-look for ectopic preg

Question 20

dot orientation

Answer 20

-provides frame of reference when doing US
-all probes have small raised bump on one side
-should always be oriented either cephalically or to pts right -> except for echocardiograms

Question 21

basic US modes

Answer 21

-2D - aka B-mode
-MC
-static or real time

-doppler (sound only)
-measure sound at specific location
-helpful in determining valvular/vascular disorders

-color
-determines blood flow
-blue away from screen, red towards screen

-M-mode:
-plots single line of US beam over time
-useful in determining movement and change

Question 22

doppler mode

Answer 22

-essentially a microphone that listens at specific point determined by the operator
-volume of turbulence recorded, plotted on across a time graph
-essentially microphone that listens at a specific point determined by operator
-volume of turbulence recorded, plotted on across a time graph
-change in volume calculated into blood flow
-change in volume calculated into blood flow

-thinner if??

Question 23

color mode

Answer 23

-transforms doppler signal information into color and superimpose it over 2D image

Question 24

M mode

Answer 24

-single beam of US machine is plotted across time
-graph that develops will show changes over time
-useful in determining change of size of dynamic structures:
-heart chambers
-heart valves
-great vessels

Question 25

summary types of US studies

Answer 25

-2D real time imaging- fetal movement, heart motion

-doppler US- circulating RBCs to assess blood flow, fetal HR, blood flow to organs

-color flow doppler- direction and velocity of blood flow cardiac valves/vasculature-blood shunting

-duplex scanning:
-combination of color flow and doppler US
-function of arteries and veins- plaques, aneurysm, and DVTs

Question 26

economic impact

Answer 26

-when incorporated earlier and more frequently into community hospital
-emergency medicine diagnostic protocols
-lower direct and indirect costs assoc with diagnostic workups
-shorter stays, avoiding additional expensive imaging tests, and reduced overall costs

Question 27

avoidance of cost

Answer 27

-les to savings:
-1,134 for private insured pts
-2,826 for out of network or uninsured pts
-181 for pts with medicare or medicaid
-avoiding additional testing
-among 49 observations included in single center study 16 resulted in a change in management which involved foregoing additional diagnostic tests
-led to faster dx and increased departmental protocol throughout

Question 28

diagnostic accuracy of lung point of care US fora cute heart failure compared with chest x-ray study among dyspneic older pts in emergency dept

Answer 28

-81 dyspneic pts evaluated with lung POCUS and compared with chest x-ray to identify acute heart failure
-67 had acute heart failure
-sensitivity of lung POCUS was significantly higher than that of chest x ray study (p=.003)
-conclusions- lung POCUS in clinical setting was highly sensitive and specific in identifying acute HF and performed better than chest x ray in an older population

Question 29

outpt internal medicine, family med, urgent care

Answer 29

-35 year old male presented with dyspnea and chest pain for 3 months
-after performing a PE PA decided to perform PCOUS lung US
-following image was obtained in region of right lower chest

Answer 30

small echogenic air bronchograms (white areas near the base of the lung)
-note that the spine is visible which is normally not visible in this view bc of aerated lung anterior to it
-large pleural effusion created perfect acoustic window to allow visualization of the spine

Question 31

KUB

Answer 31

-back pain, flank pain, hematuria, oliguria, anuria, groin pain
-renal calculi or stones are commonly encountered during KUB US exam
-hyperechoic on US
-consider an incidental finding in an asymptomatic pt