EM: Block 1 Flashcards by brandon lovin

What is the simple way to describe Dx US and what’s an example?

US signals assume a ? speed during travel through mediums

Pulse-echo principle- Sonar

Relative propagation

How well did you know this?

Not at all

Perfectly

How is relative distance determined by US?

How are sound waves formed by the US?

Time elapsed for echo to return after hitting object

Electric current passes through transducer crystals

How well did you know this?

Not at all

Perfectly

Define Piezoelectric effect

US calculations are made based on the assumption sound waves travels at the same speed through all tissues which is ? fast

Pressure-Electricity: generates constant high frequency, longitudinal, mechanical sound to be measured

1540m/s

How well did you know this?

Not at all

Perfectly

Define Depth

How does this correlate to what is seen on the screen?

Time for returning echo relative to transducer distance

Louder echo= brighter pixels

How well did you know this?

Not at all

Perfectly

Define Sound Waves

Define US

? units are used for Dx purposes

Repeated mechanical pressure wave through medium

Sound w/ frequency >20K Hz

2-15M cycles/sec (2-15MHz)

How well did you know this?

Not at all

Perfectly

Define Amplitude

This unit is AKA ?

This unit correlates to ?

Peak wave pressure (height)

Loudness

Intensity of returning Echo
Loud= large amplitude
Soft= small amplitude

How well did you know this?

Not at all

Perfectly

Define Period

Define Frequency

Time required for one complete cycle

Number of times wave is repeated per second

How well did you know this?

Not at all

Perfectly

US spend 99% of their time conducting ? function

Define Pulse

Listening
1% of time generating waves

Period of wave generation

How well did you know this?

Not at all

Perfectly

What is the relation to transducer frequency and image quality and when are they used

Higher= Inc resolution, dec tissue penetration
Linear: superficial structures/procedural guidance- vascular access, ocular US

Lower= dec resolution, inc penetration
Curved/Linear probe- bone Fxs

How well did you know this?

Not at all

Perfectly

Define Velocity

What is the relation to this part of US and imaging

Speed of sound wave
Closer= better propagation

Travels faster in bone than soft tissue
Less dense molecules (gas) slows sound (vacuum)

How well did you know this?

Not at all

Perfectly

Define Wavelength

What is the equation to determine this

Distance traveled/second

WL= propogation speed/frequency

How well did you know this?

Not at all

Perfectly

When does attenuation begin/end

What factors can affect it

Pulse generation through round trip path until returns, recorded as echo
Lack of- fluid, bright

Wavelength
Number of interfaces
Degree of homo/heterogeneity
Medium 
Tissue type/density

How well did you know this?

Not at all

Perfectly

US travels best w/ the least ? such as through ?

This explains why ? procedure is done for OB

Attenuation
Homogenous fluid filled

Transabdominal US of uterus/ovaries w/ filled bladder, creates acoustic window to posterior anatomy

How well did you know this?

Not at all

Perfectly

Attenuation occurs MC by ?

Reflection- wave redirected back to source; foundation of US

Scattering- beam hits interface smaller/irregular than bean

Absorption- acoustic to thermal energy (therapeutic US)

Refraction- redirection of sound wave when crossing medium boundaries

How well did you know this?

Not at all

Perfectly

US should evaluate anatomy at _* to maximize structure reflection

Therapeutic US uses ? principle of US

90*

Absorption, not used for Dx US

How well did you know this?

Not at all

Perfectly

What are the different modes on US and what are they used for

Curvilinear, LF probe:
B: brightness, converts amplitude of returning echo to 2D image
Used by most of EM

Phase Array probe-
M: motion, simultaneous B-mode and the waveform

How well did you know this?

Not at all

Perfectly

What is used to view/assess fetal heart rate w/ US in the ER

Define Doppler

M-mode, less energy than Doppler

Interpretation of frequency shifts (train noises)
Towards= high frequency
Away from= low frequency

How well did you know this?

Not at all

Perfectly

Doppler displays ? two pieces of info

What does Color Doppler use to produce images

Flow direction
Velocity

Pulse-Echo principle

How well did you know this?

Not at all

Perfectly

Define Power Doppler

Define Echogenecity

Amplitude/strength of motion, better for slow flow/low volume states (torsion)

Amplitude of signal reflected from structure compared to amplitude reflected from surrounding structures

How well did you know this?

Not at all

Perfectly

Define Hyperechoic

Define Hypoechoic

More echogenic/inc amplitude (brightness)

Less echogenic/less amplitude

How well did you know this?

Not at all

Perfectly

What is the leading cause of MisDx w/ US

What can be the benefit of this cause of mis-Dx

Image artifacts

Some artifacts= pathology

How well did you know this?

Not at all

Perfectly

What are 4 causes of artifacts

Define Shadowing

Attenuation/refraction
From w/in PT
Operator error
External sources

Sound hits highly reflective surface, returned w/ little energy w/out continuing to deeper structures

How well did you know this?

Not at all

Perfectly

Clean Shadows can be caused by ?

Dirty Shadows can be caused by ?

Ribs Gallstones Calcified structures

Acoustic mismatch at tissue/air interface, normally bowel gas

How well did you know this?

Not at all

Perfectly

What causes posterior acoustic enhancement

This phenomenon can be used to confirm presence of fluids where?

Sound waves passing through low attenuation, increased energy= inc echogenecity posterior w/ less attenuation

Joints
Tissue necrosis
Anesthetics after injection

How well did you know this?

Not at all

Perfectly

The presence of ? is the enemy to US Why?

Gas Difference in density disperses sound waves

# Define Reverberation artifacts Why are these bad?

Sound bounces of two highly reflective objects causing brigh arcs in equidistant intervals Obliterates B-mode image distally (lungs)

# Define Mirror Artifacts Why are these bad?

Objects appearing on both sides of a strong reflector; diaphragm during FAST NO pathology Duplication of structures leading to incorrect interpretation

# Define Side Lobes Acoustic power is AKA ? and relates to the ? produced by transducers

Lower intensity beams originating at angles to primary beam, results in false info (oblique line/acoustic echo) TVUS Output- amplitude produced by transducer Wave amplitude- determine brightness/quality

Increasing acoustic power results in ? Acoustic power is directly related to ?

Higher amplitude, stronger return echoes that increase contrast between light/dark areas Intensity

# Define ALARA Define Gain

As Low As Reasonably Achievable Control to adjust brightness w/ acoustic power

Difference between Power and Gain

P: changes brightness by changing strength of sound entering body G: inc amplification of signals after echoes have returned to transducer

# Define Time Gain Compensation What is the most frequently used knob on US

Adjustment of brightness at different depths; near/far fields Depth

What are the two reasons to adjust depth When is the zoom function most useful

Greater depth= smaller structures, fit more on display Inc depth= longer listening to collect data Measuring small structures- Need to magnify one section to focus on deeper structures, w/out changing number of pixels

# Define Cine Loop Define Footprint

Last several seconds of image saved for re-review Area that sound waves leave and return to transducer; larger better for deeper

Low frequency curved transducers have a ? footprint and are used for ? High frequency curved transducers are used for ? Linear array transducers are used for ?

Large Deep: thorax abdomen bladder Endocavitary scans (vag/rectal) Superficial structures w/ high frequency

What are phases array transducers used for? What are the land marks for internal jugular access?

Echos, small footprint= easy intercostal imaging SCM and Clavicular

What are the land marks for femoral access? What are complications from US line placement

Inguinal ligament Femoral artery Arterial/vessel puncture Bleeding PTx Hemothorax

What two vessels are preferred for peripheral access What type of transducer is used?

Basilic/Cephalic Linear

What is a screening test to eval abdominal trauma instead of an EFAST What has a better specificity and thus, the DxTest of choice in trauma centers

Dx Peritoneal Lavage CT

What are the disadvantages of doing a FAST

Operator dependent Interpreting difficulties if obese/gaseous PT Inability to differentiate hemorrhage from ascites Can't eval retroperitoneum as well as CT

What are the indications to do a FAST exam FAST can identify what 3 parts about found fluids

``` Blunt/penetrating trauma Undifferentiated HTON Subacute torso trauma Trauma w/ pregnancy Pediatric trauma ``` Presence Amount Location

FAST exams are particularly helpful in what blunt trauma scenarios

Hemodynamically unstable Unreliable PE due to intoxication, distracting injury, CNS injury Unexplained HOTN and equivocal PE

When are FASTs conducted for penetrating trauma What are the 5 eFAST windows

Uncertain immediate surgery Multiple wounds Uncertain trajectory into pericardium, lower chest or epigastrium RUQ LUQ Cardiac Pelvis Chest

?mL of fluid in abdomen/chest is needed for visual identification w/ US How much is needed in the for visualization on CXR?

250mL/20mL 50-100 in upright chest 175 in supine chest

What is the most beneficial assessment for a PTs w/ penetrating torso trauma and HOTN? What are the classic PE findings for this exam?

Cardiac FAST Distended neck veins HOTN Muffled heart tones

How is the pneumothorax exam conducted What is the MC normal sign when looking for PTx?

High freq linear probe on 2nd intercostal space, MCL x 4-5 respiration cycles Lung sliding- excludes PTx

When is the transducer dot NOT pointing to the L Define Seashore Sign Define Stratosphere Sign

Cardiac- to PTs head/L hip Parasternal long axis + lung sliding Barcode sign- no lung sliding

What is the alternating point between Seashore and Stratosphere sign If clinician can see ? and ?, PTx can be confidently excluded

Lung point sign- when lung contacts parietal pleura w/ inspiration Lung sliding B lines

If clinician sees ?, suspicion of PTx exists and is increased if ? is seen What does the lung points sign indicate

No lung sliding or B lines A-lines 100% specific for PTX and correlates to radiographic size

RUQ view LUQ view

Phased array, marker to head Phased array, marker to head/knuckles to bed

Subxyphoid view Alternate cardiac view

Phased array, marker to PTs right Phased array, marker to PTs L hip

Bladder views Lung views

Transverse: marker to R Sagittal: marker to head Linear probe, marker to head

What is the gold standard for Dx of cardiac abnormalities What are the primary indications for conducting a focused cardiac US

Echocardiography ``` Cardiac arrest Massive PEs Volume statue/fluid response Pericardial effusion/tamponade LV structure/function Unexplained HOTN Guide emergency pacing ```

PTs presenting w/ ? get cardiac US What views is the most useful for POC cardiac US and why?

Chest pain Dyspnea Trauma Syncope Subcostal 4 chamber view, No interference w/ thoracostomy, CPR, subclavian line insertions or intubations

What are four ways to increase poor quality images from subcostal 4 chamber views

US gel Shallow angle to chest wall Move transducer to R to use L liver lobe as a window Move off xiphoid/over intercostal space to image PT w/ barrel chest/large AP diameter

When using sub-xiphoid view, where are the chambers being seen What is on top of all of these landmarks

Top L: RV Bottom L: RA Top R: LV Bottom L: LA Liver

How is the parasternal long axis view obtained If done correctly, what structures will be on the right side of the images?

Align US plane w/ long axis of LV Transducer perpendicular to chest wall L to sternum w/ indicator to L hip AV/MV Proximal aorta/LA

How is the parasternal short view obtained What are the 3 views obtained

Rotate transducer 90* clockwise from parasternal long view position Aortic valve- mercedes sign Mitral valve- fish mouth view Papillary muscles

What are the 4 views obtained with the apical 4 chamber view What type of view is the apical view? When is this view preferred?

Base Mitral Apex Papillary Coronal- 4 chambers on one plane Assessing LV function and size

When using the IVC view, what finding is consistent w/ low right sided filling pressures Where is the transducer indicator pointing during this view

Collapses >50% PTs head

Screening PoC US are done on PTs >50y/o w/ pain or ? Sxs? Elective Tx of AAAs is suggested when they're what size

Groin Flank Abdomen Back Dizziness/Syncope Unexplained HOTN Cardiac arrest 5.5cm or larger

What is the triad for ruptured AAA

Pain Palpable mass HOTN Pain is most consistently found Palpating mass- unreliable HOTN- not always found in ruptures

Most AAAs rupture in ? direction causing ? effect What is the max external diameter considered normal?

Retroperitoneum Transient tamponade <3cm

When the celiac artery branches off of the aorta, what is the sign What is the sign called when passing the SMA

Seagull sign Mantle sign

What probe is used when assessing for AAAs What is the MC reason structures wouldn't be seen

Curvilinear probe Gas

How is an AAA scan conducted What are the 3 measurements taken

Transverse view- from prox (Celiac/SMA) to distal (bifurcation) Prox: level to Celiac/SMA Mid: between xyphoid and bifurcation Distal: umbilicus, above bifurcation

What is done during the sagittal view of the AAA exam AAA US Summary

Video only, no measurements Curvilinear- prox to dist Transverse: marker to PT R, Measure 3- prox, mid, dist Saggital: marker to PT head

When is an US of the eye warranted What is the normal measurement of the optic nerve

HA/AMS Acute vision changes Trauma Inc ICP 3mm

How do you differentiate retinal or vitreous detachment

Retinal- attached posterior, vertical flow Vitreous- not attached at disc, horizontal flow

What causes a "comet-tail" artifact when doing an eye US? Ocular Summary

Doppler w/ metal debris ``` LInear transducer w/ 2 orthogonal planes: Transverse- marker to PT R Sagittal: marker to PTs head Measure ONSD at 3mm from retina, N=<5mm >5mm= Inc ICP (+20mmHg) ```

Where are most DVTs Dx What is the gold standard imaging test for Dx DVTs?

Proximal veins of LE US of prox LE

Most algorithms for Dx DVTs use ? combos of info Flow Chart

Clinical suspicion D-dimer Compression US DCT Deck- Slide 7

Where do we start the US assessment for DVTs? What structure is the compression assessed at?

Junction of great saphenous/ common femoral Inguinal ligament

Where is the popliteal vein located? Where does the popliteal vein trifurcate?

Adjacent/superficial to popliteal artery, mid fossa Pop-on-top Distal popliteal fossa

DVT summary

Linear transducer Curvilinear if obese w/ marker to PT R Supine, frog leg w/ 30* reverse trandelenberg Scan prox femoral/popliteal veins, compress q1cm x 10cm

US are more sensitive than CXR for Dx of ? Fxs How do foreign bodies that have been retained for >24hrs appear on US? What can be done to improve ability to find/visualize foreign bodies

Rib Halo from edema/pus Local anesthetic adjacent to foreign body

If an abscess is seen on US but has color flow, what does that mean? What appearance doe cellulitis have on US?

Necrotic lymph node Cobblestoning

# Define Anisotropy What type of foot print is seen at the top of the screen for a HF transducer? What type of foot print is seen if a LF probe is used?

Not 90* causing tendon to appear dark/torn when not Flat across Curved shape into screen

2D imaging can be AKA ? or ? Where is Morrison's pouch and what is it AKA? What is the name of the fascia that surrounds the pouch?

B-mode Gray Scale imagines Between Liver/Kidney Hepatorenal recess Gerota's fascia- anterior (Zuckers on posterior)

The intensity of US beam, or the amount of energy, determines the ? of the US How do images appear if the near or far fields are over/under gained?

Bioeffects Near, top half is darker if under gained: Far field, lower half is darker and under gained

Sector size of the linear transducer is identical to ? Phased array transducer is sometimes AKA ?

Footprint of the transducer Cardiac probe

When attempting peripheral IV access, normally ? vein is used What does E-FAST stand for

Basilic vein Extended Focused Assessment w/ Sonography in Trauma

If PT has Neg-FAST exam and are not stable, what is the next step? It is important to capture the pole of ? on ? side

Repeat/continue assessment R sided, inferior kidney pole

What structure makes visualization of fluids appear first on LUQ view Where would this be seen

Splenocolic ligament Sub-diaphragm

Free fluid in abdomen is usually going to pool on ? side What valve leaflet is being assessed during the PSL view

L side Anterior leaflet of Mitral valve

? bladder view is more sensitive What probe is used for the abdominal and pneumothorax scans

Saggital R/L/Pelvic- phased array Pneumo- linear

What are the parts of a Sky Ocean Beach sign What part is lost during a PTx

Sky- soft tissue Ocean- hyper echoic pleura Beach- motion artifacts Beach

Subxyphoid view transducer and position

Phased array, PTs R | Alt: PSL, phased array, PTs L hip

Bladder view transducer and position

Phased array Transverse: PTs R Sagital: PTs head

Lung view transducer and position

Linear probe, PTs head

What is the best view to ID mod/large pericardial effusion What is the best view to ID gross cardiac activity/stand still

Subcostal Subcostal or Parasternal

What is the best view to assess heart chamber size What view is best for assessing 2d EF

Apical 4 chamber Subcostal PSL or Apical

What view is the best for measuring E-point septal separation to estimate EF What view is best for evaluating gross valve motions

PSL Parasternal long or short

What view is best for assessing volume status by IVC size/collapsability

Subcostal sagittal view

What is the name of the sign seen in the PSA view

Mercedes sign of aortic valve

Where is the indicator pointing during the apical 4 chamber view Where is the proximal IVC located?

PT R hip Subcostal midline saggital view: posterior to liver into RA

Where is the transducer pointing during the IVC view All cardiac US views use ? probe

PTs head Phased array

Sub-Xyphoid View

PTs R: RV RA LV LA

PSL View

PTs L Hip: RV LV Ao LA

PSS View

PTs R hip: | Mercedes Fish Papillary

4AC View

PTs R Hip at PMI: RV LV RA LA

What was the rule about seeing a vein that crosses over in the abdomen One time AAA screenings are done for men between ? age that have tobacco Hx

Above SMA= splenic Between SMA/Aorta= L renal going to IVC 65-75y/o

? is most mis-Dx as AAA Type of artifact

Kidney stone Shadow Edge Artifact Gas Reverberation Acoustic enhancement Mirroring Side lobes

Septal thickness measured w/ MSK probe What is NOT seen on PSS view

PSL Linear ???

How do you adjust for PAE Sector size larger than transducer

Gain Curvillinear

Plot end point separation Parasternal separation On abdominal exam, IVC takes on ? appearance

M mode Tear dropped

Sagittal view of aorta, what is the sequence of structures branching off How can you decrease optic echoes that are creating difficulty Dx borders of optic nerve sheath

Celiac artery SMA Dec gain due to PAE

How could a subtle lens dislocation be accentuated on US?

Consensual pupillary constriction

Well's Score

S/Sxs of DCT- 3 PE most likely Dx- 3 Tachy- 1.5 Immobile/Post-op x 4wks- 1.5 Prior DVT/PE- 1.5 Hemoptysis- 1 Ca/Tx x 6mon- 1 Low <2 High>6 Unlikely 0-4 Likely 5 or +

How do you know if you're looking at PTs R or L leg on US during DVT scan

R: GSV runs medial to CFV | Arteries to L side of screen