Ultrasound (US) Flashcards by Preeti Gulve

High frequency sound waves beyond the range of human hearing is called

ultrasound

(20 Hz to 20 kHz = normal range)

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What is the normal frequency of soundwaves

for diagnostic ultrasounds?

1 - 30 MHz

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What is the propagation velocity of sound?

1540 m/s

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Ultrasound depends on __________

calculated as the velocity times the tissue density

Acoustic Impedance (Z)

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Frequency x Wavelength = ________

Velocity

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If you want to achieve better resolution on an ultrasound,

you must:

_____ frequency and _____ wavelength

increase frequency

and

decrease wavelength

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If you want to achieve better penetration on an ultrasound

you must:

______ frequency and _______ wavelength

decrease frequency

and

increase wavelength

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Attenuation occurs with _______ frequencies

which causes less information to return

higher

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Penetration ______ as

frequency and resolution increase

decreases

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Increasing the distance from the transducer can

cause ________, or loss of the ultrasound

attenuation

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A reflected soundwave is generated at the interface of

an _________ __________

impedance__mismatch

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Constant impedance occurs when an ultrasound

is traveling through a __________ medium

homogenous

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Impedance (Z) is a characteristic of the

_________ medium

propagation

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Round trip transit time is directly related to the _________,

or the distance of the sound wave reflection site

depth

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Total roundtrip time divided by 2

is representative of the _______

interface

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What are the 4 assumptions made by Ultrasound?

Assumptions of US:

_{The speed of sound in all tissues is 1540 m/s}

_{The US beam only travels in a straight line with a constant rate of attenuation}

_{The US beam is infinitely thin with all echoes originating from its central axis}

_{The depth of the reflector is accurately determined by the time for sound to travel from the transducer to the reflector and back again}

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What are the 6 artifacts that you may encounter with

Ultrasound?

Acoustic Shadowing

Acoustic Enhancement

Edge Shadowing

Reverberation Artifact

Slice Thickness Artifact

Mirror Image Artifact

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This artifact occurs distal to highly reflective objects

(high acoustic impedance mismatch)

because the interface absorbs or reflects the entire sound

resulting in an anechoic area

Acoustic Shadowing

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Clean Acoustic Shadowing occurs at the interface of

tissue and ______

bone

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Dirty Acoustic Shadowing occurs at the interface of

tissue and ______

gas

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Which type of acoustic shadowing occurs

when most of the sound waves get absorbed

resulting in a complete absence of reverberation artifacts?

Clean Acoustic Shadowing

(tissue-bone interface)

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Which type of acoustic shadowing occurs

when 99% of the sound waves get reflected

and a resultant reverberation artifact is produced?

Dirty Acoustic Shadowing

(tissue-gas interface)

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What type of acoustic shadowing is present if

a homogenous anechoic shadow is produced?

CLEAN

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What type of acoustic shadowing is produced if

an inhomogenous/reverberation artifact is present?

DIRTY

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This type of ultrasound artifact occurs when fluid of homogenous acoustic impedance attenuates *less* sound than the surrounding tissues, and the US machine overcompensates resulting in a *hyperechoic* area *distal* to the structure

Acoustic Enhancement

This US artifact occurs as a small shadow at the border of round structures

Edge Shadowing

This US artifact occurs at curved surfaces like the urinary bladder and the gallbladder and can mimic sediment

Slice Thickness Artifact

This US artifact occurs at highly reflective **air-fluid** interfaces ^{(like the diaphragm-lung or pericardium-lung interfaces)} and at **concave surfaces**

Mirror Image Artifact ^{(false image produced on the other side of the reflector)}

Coupling Gel is used for ultrasounds because \_\_\_\_\_\_ is the enemy of US

_AIR_

\_\_\_\_\_\_\_\_ prevents loss of sound due to the compressibility of air. Air acts like a shock absorber and dampens the US wave.

_Coupling Gel_

What are the 4 types of US transducers?

Multi-frequency Linear Sector Convex

\_\_\_\_\_\_\_ crystals both emit and receive ultrasound and are a component of US transducers

_Piezoelectric_ crystals

The **smaller** the animal, the _____ the frequency (MHz) required for ultrasound

_higher_

T/F: Patients must fast for 12 hours before an ultrasound can be performed

TRUE

Stress must be avoided in patients that will be undergoing ultrasound because stress can cause \_\_\_\_\_\_\_\_\_

_aerophagia_ ^{(AIR IS THE ENEMY OF ULTRASOUND!)}

An ultrasound is performed on an animal in \_\_\_\_\_\_ recumbency

_dorsal_

In order to scan the **sagittal plane**, the transducer must be ________ oriented

_cranially_

In order to scan the **transverse plane**, the transducer must be oriented \_\_\_\_\_\_\_\_\_\_\_\_

_towards the examiner_

What side of the body will you find the spleen?

LEFT

The bladder and prostate are seen when scanning the _____ side of the patient

_left_

The liver is seen when scanning the \_\_\_\_\_\_ side of the patient

_right_

The equivalent term for opacity on a radiograph

Echogenicity

Vascularity can be assessed on ultrasound by utilizing \_\_\_\_\_\_\_

_Doppler_

Homogenously black structures seen on ultrasound that are related to very low intensity of returning echoes

Anechoic

This term refers in general to white structures seen on an ultrasound due to **high intensity** of returning signals

Hyperechoic

Put the following in order of echogenicity from least echogenic (black) to most echogenic (white): ^{bone/air, liver, spleen, prostate, urine, kidney}

Blackest to Whitest: Urine Kidney Liver Spleen Prostate Fat Bone/Air (UK Loves Super Pretty Foreign Babes)

If a fluid appears **anechoic** on US, it is most likely \_\_\_\_\_\_\_\_\_

_Transudate_

If a fluid appears speckled or more echogenic, it is most likely \_\_\_\_\_\_\_\_

_Exudate, Blood, or Chyle_

What two locations in the abdomen will be the first to accumulate free abdominal fluid?

Apex of Bladder Between the Liver Lobes

T/F: Arteries are easily visualized in ultrasounds, but veins are nearly invisible

FALSE! VEINS are Visible, arteries are not!

How would you distinguish the portal veins from the hepatic veins on an ultrasound?

Portal veins have *hyperechoic* walls (white) and Hepatic veins have *isoechoic* walls ^{(blends in with surroundings)}

The liver is \_\_\_\_echoic to the spleen and coarser in appearance

_hypoechoic_ _{(liver is darker than spleen)}

When examining the liver in ultrasound, diffusely *hypoechoic* parenchyma with a prominent portal vein wall are indicative of what conditions?

Acute hepatitis Venous congestion (would also see enlarged hepatic veins) Lymphosarcoma

When examining the liver on ultrasound, a diffusely *hyperechoic* parenchyma (whiter) with reduced visualization of portal vein wall is indicative of what conditions

Diabetes mellitus Hyperadrenocorticism Hepatic Lipidosis Lymphosarcoma

A normal gallbladder is \_\_\_\_\_echoic to liver parenchyma

_isoechoic_

T/F: When examining the gallbladder of a normal dog or cat, the intrahepatic biliary ducts (hepatic and cystic) are readily visualized

FALSE! intrahepatic biliary ducts are NOT detected in a normal dog or cat

The ___________ of the gallbladder can be traced in normal cats, but not in dogs due to overlying gas in the GI tract

_Common Bile Duct_

T/F: Sludge, or anechoic content, can be seen in a normal animal's gallbladder

TRUE

A thickened gallbladder wall is indicative of

Cholecystitis

If hyperechoic clean shadows are seen in the gallbladder, the most likely cause is

Choleliths (mineral deposits)

Dilation of the gallbladder and common bile duct are indicative of

obstruction

The normal echogenicity of the splenic capsule is

hyperechoic (white)

The spleen has _______ echogenicity than the kidney

_greater (whiter)_

Fat and the splenic vein can be seen at the _____ of the spleen

_hilus_

The renal pelvis of the kidney is \_\_\_\_\_echoic due to fat

_hyperechoic (white)_

The renal cortex is ______ echogenic than the spleen

_less_ Renal cortex is darker than the spleen

The renal cortex of the kidney is _____ echogenic than the renal medulla

_more_ Renal cortex is whiter than the renal medulla

The renal pelvis is normally ______ mm wide

_1 - 2 mm_

The **proximal ureter** is enlarged if it is greater than _______ mm

_3 - 4 mm_

The normal renal size in **cats** is ______ +/- 0.46 cm but in dogs, the size is variable

_3.66_

When would you want to ultrasound the urinary system?

To examine bladder neoplasia and calculi

The bladder appears \_\_\_\_\_echoic on US

_anechoic (black)_

The _______ is in close apposition with the liver caudally and lies cranial to the last pair of ribs

_stomach_

In a **dog**, the stomach is normally \_\_\_\_mm in thickness

_3 - 5 mm_

In a **cat**, the stomach is normally \_\_\_\_\_mm in thickness

_2 mm_

What are the layers and corresponding echogenicities of the layers of the stomach?

Serosa- hyper Muscularis- hypo Submucosa- hyper Mucosa- hypo Lumen-Mucosa Interface- hyper

\_\_\_\_\_\_ peristaltic contractions per minute are normal

_4 - 5_

In a ______ the jejunum and the ileum are of similar thickness but In a _______ the duodenum and the ileum are similar

_dog_ - jejunum and ileum _cat_ - duodenum and ileum

The thickest layer of the intestines is the \_\_\_\_\_\_\_\_ and it is hypoechoic

_mucosa_

Which pattern is seen in the small bowel if it is in a collapsed state, is hyperechoic, and no acoustic shadowing is present?

Mucous pattern

Which pattern is seen in the small bowel if the luminal content is anechoic?

Fluid pattern

Which pattern is seen in the small bowel if it is hyperechoic and acoustic shadowing is present?

Gas pattern

The cecum in a ____ is difficult to identify due to intraluminal gas

_dog_

Ultrasound (US) Flashcards

(83 cards)