Physics, Artifact, M-mode

Question 1

What are the types of cavitation?

Answer 1

• Squeeze flow
  
  • acceleration of blood as occluder approaches stop causing drop in pressure
• Vortex flow
  
  • turbulence at edge of rapidly moving occluder

Question 2

What is velocity (propagation speed) error artifact?

Answer 2

• sound propogates through some structures at velocity other than 1540 m/sec
  
  • • takes longer to travel through a structure - which is assumed by the ultrasound machine

Question 3

What is specular reflection?

Answer 3

• mirror-like reflection of waves from a surface, in which waves from a single incoming direction (a ray) is reflected into a single outgoing direction.
• angle of reflection equals angle of incidence for objects > 1 wavelength diameter (~0.5mm)

Question 4

What is cavitation?

Answer 4

• rapid formation of vaporous microbubbles in a fluid due to a local reduction in pressure

Question 5

What are High Intensity Transient Signals (HITS)?

Answer 5

• under some conditions (vortices), vaporous microbubbles can coalesce into larger bubbles
  
  • degassing: removal of gasses (principally CO2 in blood) from liquid medium
  • larger bubbles persist and ar visible on echo
• no demonstrated neurologic sequelae from HITS microbubbles

Question 6

Why are bubbles such good reflectors? Why do we see them with prosthetics?

Answer 6

• they have a very low acoustic impedance
  
  • acoustic impedance (velocity x density)
• interface between materials with dissimilar acoustic impedances (velocity x density) reflects sound
  
  • 23 (air) vs. 1465 (water)

Question 7

To reduce aliasing on color-flow Doppler, a sonographer should perform this action?

Answer 7

• Changing the baseline shift
  
  • allows velocities to be displayed up to twice th original Nyquist limit

Question 8

What is pulse repetition frequency (PRF)?

Answer 8

• number of pulses of a repeating signal per unit time
• inversely related to PRP (PRF = 1 / PRP)
• inversely related to imaging depth (PRF x 1/d)

Question 9

What environment can sound waves not travel through?

Answer 9

• vacuum
  
  • pressure waves can only be transmitted through physical media consisting of molecules that interact with each other

Question 10

What is the upper limit of human hearing?

Answer 10

20,000 Hz or 20 kHz

Question 11

The frequency of a sound wave is measured in Hz as the:

Answer 11

• number of times particles vibrate each second in the direction of wave propogation
• 1/s
  
  • the number of times a particle in a conducting medium vibrates per unit time

Question 12

Ultrasound imaging is usually performed in what frequency range?

Answer 12

• 1-30 MHz
  
  • lower frequencies (greater penetration) –> larger organs or deeper structures
  • higher frequencies (better spatial resolution) –> smaller, more superficial structures

Question 13

Define wavelength

Answer 13

the distance a wave travels during a single cycle

Question 14

What type of tissue results in the fastest loss of ultrasound wave strenght?

Answer 14

• Lung
  
  • because of the high content of air and the abundance of highly reflective tissue/air interfaces, the sound waves dissipate in the lung so fast that the lungs are virtually opaque to ultrasound

Question 15

What is the main goal of the gel used during ultrasound imaging?

Answer 15

• Improve contact between the transducer surface and the skin
  
  • eliminates any tissue/air interfaces which are highly reflective and thus prevent ultrasound transmission

Question 16

What are Piezoelectric crystals?

Answer 16

materials that respond to electric signals by vibrating and generating acoustic waves and vice versa

Question 17

To better assess rapidly moving structures, a sonographer should perform this action?

Answer 17

• Narrow scan sector width and decrease imaging depth = increased frame rate
  
  • Higher frame rate is required to increase temporal resolution
    
    • some machines enable direct manipulation of frame rate, others can be adjusted by sector width and imaging depth

Question 18

How do Piezoelectric crystals generate ultrasound images?

Answer 18

• transmit waves by “exciting” the crystals in the transducer by an electrical stimulus,
• then receiving the ultrasound waves reflected by structures inside the body,
• translating them back into electrical signals that are used to form an image of the reflecting structures

Question 19

Define Doppler shift?

Answer 19

• change in the frequency of a sound wave reflected by a moving target
  
  • negative / red shift
    
    • object moving away
    • wavelength made longer (increased)
    • frequency decreased
  • positive / blue shift
    
    • object moving toward transducer
    • frequency incerased
    • wavelength decreased

Question 20

Define doppler angle?

Answer 20

• angle between:
  
  • the direction of flow
  • ultrasound beam

Question 22

With time gain compensation, the machine is generally preset to perform this action?

Answer 22

• Decrease signal in near field, increase signal in far field
  
  • increasing depth = increased attenuation
  • TGC accounts for this signal loss by effectively incresing gain in parallel with increase in depth
    
    • many modern systems automatically account for this so the knobs should be left in neutral position to start with then adjusted as needed

Question 23

Define Harmonic imaging?

Answer 23

Echocardiogaphic images are formed from returning echoes at twice the insonifying frequency (second harmonic)

Question 24

When does aliasing occur?

Answer 24

when doppler shift of high-velocity flow exceeds the Nyquist limit (1/2 the Pulse Repetition Frequency)

Question 25

What are the two forms of "harmonics" or image enhancement currently used in diagnostic ultrasound?

Answer 25

* native tissue harmonic imaging * contrast harmonics

Question 26

Define contrast harmonics

Answer 26

* occurs when tiny bubles are insonified at a lower frequency than their natural frequency of vibration * the vibrating bubbles then radiate back significant amounts of energy at the second harmonic * requires a high-pass filter on the ultrasonic receiver to eliminate signal at the fundamental frequency * the second harmonic image will show the echo contrast with significantly enhanced intensity relative to the surrounding tissue, which does not reflect the harmonic frequency

Question 27

The energy of the transmitted ultrasound wave can be changed by adjusting which of the following?

Answer 27

* Power * increasing the power increases the energy / heat delivered to the tissues * increased gain will not do this * visually this can create similar changes compared to adjusting the gain, which increases the amplitude of the signal

Question 28

Define spatial resolution of an ultrasound image?

Answer 28

* smallest distance between two objects that allows distinction between them * also determines the size of the smallest object that can be visualized

Question 29

Image resolution for a region of interest can be improved by this action?

Answer 29

Increasing the write zoom

Question 30

What does time gain compensation do?

Answer 30

* part of postprocessing of the reflections designed to correct for beam attenuation as it travels through the body * aims to provide a correction for the loss of intensity (or attenuation) by all these different mechanisms (scattering, absorption, reflection) * based on assumption that acoustic properties of surrouding tissues are the same

Question 31

The dynamic range of echoes displayed on the screen is adjusted by this?

Answer 31

* Compression control * used to include or suppress weak echoes

Question 32

When does time gain compensation become inaccurate?

Answer 32

* large differences in acoustic properties between adjacent tissues * contrast agents that show much stronger attenuation * This is the reason why acoustic shadowing artifacts are frequently seen distal to contrast filled blood pools, such as ventricles or atria

Question 33

Attenuation is the combined result of these:

Answer 33

* scattering * absorption * reflection

Question 34

The strength of the transmitted ultrasound wave is controlled by adjusting this?

Answer 34

Power control

Question 35

What does Gain Control do?

Answer 35

determines to what extent the received signal is amplified

Question 36

What is Range ambiguity artifact

Answer 36

* Deeper structures --\> appear closer to the transducer than true location * Occurs with high Pulse Repetition Frequency (PRF): * when a second pulse is sent out, before the first signal along the same scan line is received * Pulse repetition period determines maximum depth imaged * US does not "disappear" beyond this depth and may be strong enough to return a signal * Machine assumes all returning signals are result of most recent pulse

Question 37

If a rapidly moving structure such as a cardiac valve appears to be moving in slow motion, what may be set too high?

Answer 37

* Persistence * images can be averaged together to create a smoothing effect by increasing persistence * lower persistence maintains temporal resolution and can keep a structure from appearing as though it were moving in slow motion

Question 38

What does compression control do?

Answer 38

determines the dynamic range of received signals that are used to create the image

Question 39

What is the difference between read and write zoom?

Answer 39

* Read zoom only magnifies the image without a change in resolution * Write zoom increases line density and number of pixels in a given area

Question 40

What does a positive doppler shift indicate?

Answer 40

indicates that the reflector is moving so that the angle between the transmitted beam and the direction of flow is \> 90 degrees

Question 41

What does a Doppler shift of zero indicate?

Answer 41

* indicates that the reflector is stationary or moving in a direction perpendicular to the beam * Doppler angle = 90 degrees --\> flow is neither toward nor away but perpendicular to the beam

Question 42

Filtering eliminates "ghosting" artifact by removing this?

Answer 42

* Low-velocity signals * when imaging higher-velocity regions, movement of cardiac structures produces low-velocity signals that appear on the screen as color and make it harder to interpret the area of interest

Question 43

What is Pulsed repetition period (PRP)?

Answer 43

* time between pulses * directly related to imaging depth

Question 44

Increasing scan line density with a fixed sector width results in this?

Answer 44

Increase in spatial resolution * increased resolution at the cost of decrease in frame rate and temporal resolution

Question 45

The spatial resolution of an ultrasound image is equal to this?

Answer 45

* size of a pixel in the relevant direction * also resolution is directly related to wavelength

Question 46

Define temporal resolution

Answer 46

* shortest time between two events that allows distinction between them * determines the shortest duration of an event that can be detected but "with confidence"

Question 47

Define contrast resolution

Answer 47

* Minimal difference in the parameter displayed in the image as distinct pixel intensities * reflection intensity in US images

Question 48

What can be done to increase image resolution?

Answer 48

* increase write zoom * reducing sector width (while maintaing scan lines --\> increased spatial resolution) * changing focal point on display

Question 49

The temporal resolution of a sequence of ultrasound images is equal to this?

Answer 49

**directly related to frame rate** * increased FR = improved TR * decreased FR = decreased TR

Question 50

What does compression control do?

Answer 50

* used to adjust the dynamic range of echoes displayed on the screen * can be used to include or suppress weak echoes

Question 51

Define duty factor

Answer 51

the fraction of time the transducer is sending compared to the time it is receiving

Question 52

Describe how PW doppler works

Answer 52

* transducer sends out packets of US waves in a single pulse * transducer waits for waves to interact with the subject and return to the transducer where frequency shift is measured * transducer will only send out another pulse after it receives the preceding pulse * PW doppler can determine the velocity of blood cells at a very specific spatial location * because the time it takes for the beam to return is a known constant (velocity of US in tissue = 1540 msec)

Question 53

What are the positives/negatives of PW doppler when compared to CW doppler?

Answer 53

* Positive * spatial localization better * Negative * there is a maximum velocity that can be measured * can only sample at a defined pulse rate frequency (PRF) * PRF is the time it takes to send out and receive a signal pulse

Question 54

What is the Nyquist Limit?

Answer 54

* Maximum velocity that can be sampled without aliasing * equal to = PRF/2 * Synonymous with aliasing

Question 55

What are ways to reduce aliasing (and thereby increase the Nyquist Limit)?

Answer 55

* change the baseline * increase the PRF * decrease the imaging depth * decrease the frequency of the transducer * decrease the size of the sampling volume

Question 56

What are the positives/negatives of CW doppler when compared to PW doppler?

Answer 56

* Positive * Can sample much higher velocities (because it is constantly sending/receiving pulses) * like those seen in the LVOT / aorta * not limited by PRF * Negative * inability to localize velocity to a specific location * samples all frequency shifts along a given sample line

Question 57

Answer 57

Myocardial Speckle tracking * speckles are formed from interface patterns between ultrasound and the myocardium

Question 58

What are the 2 main assumptions when working with the Bernoulli equation?

Answer 58

* Linear acceleration * Negligent viscous friction

Question 59

What changes will result in improved near field spatial resolution?

Answer 59

* changing to a high frequency probe (shorter wavelength)

Question 60

What are two ways to increase temporal resolution?

Answer 60

* decreasing depth * narrowing the sector width

Question 61

What is one way to avoid Range Ambiguity artifact?

Answer 61

decreasing PRF when scanning deeper

Question 62

In a patient with A-fib and calcific aortic disease, what adjustment needs to be made when obtaining continuous wave (CW) Doppler in order to capture the best representation of the aortic velocity in one image?

Answer 62

* Lowering the sweep speed * Patients with A-fib will have varying RR intervals resulting in variable peak velocities across a stenotic AV due to differing stroke volumes * important to calculate an average of 10 cardiac cycles * lower sweep speed allows you to see more cardiac cycles per frame, allowing for calculation of the average velocity

Question 63

Describe the findings

Answer 63

**Reverberation artifact** * appears as parallel equally spaced lines extending from the object away from the transducer * at increasing depths * and more distant than the true object

Question 64

Define reverberation artifact

Answer 64

* occurs when an ultrasound beam encounters two strong parallel reflectors * ultrasound waves will reflect back and forth between the reflectors ("reverberates"), the US transducer interprets the sound waves returning as deeper structures since it took longer for the wave to return to the transducer * amount of reflected energy is proportional to the difference in the impedance of the two media: the larger the impedance mismatch, the higher the probability of reflection to occur

Question 65

What objects typically cause reverberation artifact?

Answer 65

* metallic valves * calcified structures

Question 66

How can you eliminate reverberation artifact?

Answer 66

* Decrease Gain * Alternative imaging windows / angle of insonation * Change: * depth of transducer * frequency of transducer

Question 67

Describe the findings

Answer 67

**"comet-tail" artifact** * type of reverberation artifact * multiple reverberations from very closely spaced reflectors merge * appears as a single, long, hyperechoic echo, located parallel to the beam's main axis * Commonly seen with mechanical heart valves, cholesterol crystals in adenomyomatosis * not to be confused with "ring-down" artifact which is a series of reverberations behind trapped air bubbles (not commonly seen in Echo)

Question 68

Describe the findings

Answer 68

Comet-tail artifact

Question 69

Describe the findings

Answer 69

Reverberation artifact

Question 70

# Define shadowing artifact? What causes these artifacts? How can you reduce or eliminate this artifact?

Answer 70

* acoustic shadowing that results in the absence of echoes behind a strong reflector * strong reflector prevents wave propagation distally * Causes: mechanical valve, calcification, bioprosthetic ring's * Reduce: alternative windows, increase gain or TGC

Question 71

Describe the findings

Answer 71

**Enhancement Artifact** * Opposite of shadowing artifact * Echo enhancement of images that occurs distal to weak reflectors (cyst, bladder) * medium through which the US wave traveled has a lower attenuation rate than soft tissue, beam is attenuated less than normal * Echoes below the weak reflector are enhanced and those structures appear to be brigher or hyperechoic * Error of TGC - overcompensates through fluid-filled structures causing deeper structures to be brighter

Question 72

How does mirror image artifact occur?

Answer 72

* created when * sound is reflected off a strong reflector, which acts like a mirror * sound is redirected toward a second structure which is closer to the transducer than the reflector * secondary structures reflect the wave back to the strong reflector --\> back to the transducer * Appears as a symmetric signal of less intensity than the true signal in the opposite site of the baseline * "Image on two sides of the reflector"

Question 73

What assumptions are violated in mirror image artifact?

Answer 73

* sound travels in straight lines * sound travels directly to the reflector and back

Question 74

What can be used to compensate for image losses due to attenuation?

Answer 74

* Increasing Gain * amplifies the return signal * can come at the expense of greater noise

Question 75

What is the most common strong reflector causing mirror image artifact?

Answer 75

the lung

Question 76

Give an example of a common mirror image artifact?

Answer 76

* double-barreled aorta * seen in suprasternal notch window

Question 77

What is one way to correct for mirror image artifact?

Answer 77

* 2D Echo --\> change scanning angle * Spectral Doppler --\> decrease power output or gain

Question 78

Describe the findings

Answer 78

**Mirror image artifact** * strong reflector is the pericardium * replica of mitral valve below the pericardium at equal distance to the from pericardium to the true mitral valve * displayed under a strong reflector at equal distance between the strong reflector and the true object * appears as a symmetric signal of less intensity in the opposite site of the baseline * It can be seen in two-dimensional, color, and spectram echocardiography (cross talk artifact)

Question 79

Describe the findings

Answer 79

* Mirror image artifact on Color Doppler * descending aorta with appearance of a double lumen

Question 80

Define pulse repetition frequency

Answer 80

number of pulses per unit time (pulses per second) * decreased PRF --\> pulses are more spread out

Question 81

What is the best way to avoid / improve mirror image artifact?

Answer 81

**Decrease Gain**

Question 82

What conditions will result in paradoxical septal motion of the IVS?

Answer 82

Characaterized by early systolic anterior (rightward) motion of the septum * LBBB * RV pacing * RV volume overload * severe TR * ASD * Aortic valve replacement **Aortic insufficiency will have normal septal motion (posteriorly or leftward in systole)**

Question 83

What is one advantage of M-mode vs. 2D Echo?

Answer 83

**Superior temporal resolution** * much higher sampling rate than 2D Echo

Question 84

What is the most specific sign to suggest cardiac tamponade on M-mode?

Answer 84

**RV diastolic collapse** ## Footnote ​

Question 85

# Define pseudodyskinesis When is the associated condition?

Answer 85

* **Diastolic flattening of the inferior / inferolateral wall** * **Advanced liver disease**

Question 86

What is the sampling rate in M-mode?

Answer 86

**\> 1,000 samples / second** * excellent temporal resolution * usefuly for structures that move rapidly

Question 87

Describe the findings

Answer 87

* A * atrial contraction * B * C * represents the end of diastole and closure of MV * D * represents the beginning of diastole, when MV leaflets open * E * early passive filling of the LV, maximal opening of the valve occurs * corresponds to E-wave of the mitral inflow (obtained by PW doppler) * F * valve closes in mid-diastole

Question 88

Describe the findings and diagnosis

Answer 88

Hypertrophic cardiomyopathy with SAM

Question 89

Describe the findings and diagnosis

Answer 89

MVP of the posterior mitral valve leaflet during systole

Question 90

Describe the findings and diagnosis

Answer 90

Severe MS * loss of the M-configuration * flattening of the E-F slope (blue arrow) * more flat --\> more severe

Question 91

Describe the findings and diagnosis in regards to his volume status * middle aged man with dyspnea * BP 120/90mmHg

Answer 91

**Stroke Volume is low** * patient with idiopathic dilated cardiomyopathy * marked LV dilation, with an LVEDD ~ 6cm and LVESD ~ 5.5cm * **e-point septal separation** * large separation between the anterior leaflet of the mitral valve and the septum * peak anterior position of the anterior leaflet is known as the e point in M-mode parlance * This sign is associated with a low forward stroke volume * LV dilation by itself does not lead to an abnormal e-point septal separation

Question 92

What effect does imaging depth have on fram rate?

Answer 92

* Decrease depth --\> increase frame rate = better resolution * Increase depth --\> decrease frame rate = worsening resolution

Question 93

What effect does decreasing / narrowing sector width have on: * frame rate * temporal resolution * scan lines per pixel

Answer 93

increased frame rate increased temporal resolution decreased scan lines per pixel

Question 94

Continuous spectral Doppler image displays the strength of each velocity component by assigning to them:

Answer 94

**Different gray scale levels** * each vertical line represents a power spectrum of the Doppler signal at one time point * brigthness of each point indicates how predominant the specific velocity is at that moment

Question 95

Color pattern characterizing turbulent flow in color-flow Doppler

Answer 95

**Mosaic**

Question 96

Describe how phased-aray transducers work? What is the benefit?

Answer 96

* use differences in phase of pulses transmitted by individual elements * **to steer the US beam in different directions** * **and thus scan a "slice" rather than a single line**

Question 97

The main cause of acoustic shadowing artifact is the inability of the imaging system to accurately compensate for this:

Answer 97

**Increased attenuation by structures such as contrast-filled ventricular cavity**

Question 98

What is one way to reduce shadowing artifacts?

Answer 98

**using less contrast material**

Question 99

What has been adjusted to result in greater contrast between the images?

Answer 99

**Compression** * also known as Dynamic range * describes the difference between the highest and lowest amplitude received signals that can be displayed * increasing dynamic range --\> * allows echoes of higher and lower intensity to be displayed * may be helpful in differentiating endocardial borders * decreasing dynamic range --\> * more black and white high contrast is produced

Question 100

What has been adjusted to improve the resolution of: * LV apex (A) * mitral valve (B)

Answer 100

**Focus**​

Question 101

Describe the findings

Answer 101

Doppler flow pattern with **Low-velocity filter** turned on * velocities between 0 and 20 cm/s are not visible --\> low velocity filter on * also known as wall filter

Question 102

What happened to the sweep speed in the image?

Answer 102

**Decreased** * Sweep speed does not impact the US beam itself but rather the speed with which the Doppler spectrum moves across the screen * Higher sweep speeds * useful in making detailed time estimates * Lower sweep speeds * better appreciation of respiratory variation or other muticycle events

Question 103

What is one requirement in tissue harmonic imaging in regards to depth?

Answer 103

**Need to travel sufficient depth to generate harmonics and thus images with less noise and better clarity** * harmonic imaging is dependent upon sound waves being distorted as they pass through tissue --\> generating higher frequency harmonics

Question 104

Define smoothing

Answer 104

* **refers to the process of averaging adjacent pixels to create a "smoother" image** * can be used to reduce the pixelated appearance

Question 105

What is the most useful tool to distinguish ascending aortic artifacts from intimal flaps?

Answer 105

**M-mode during TEE** * useful in showing that intimal flaps have independent motion

Question 106

What causes linear artifacts in the ascending aorta?

Answer 106

Reverberation

Question 107

When will a consistent linear image (artifact) in the aorta be visualized on TEE?

Answer 107

**Aortic diameter \> LA diameter**

Question 108

Where are TEE artifacts in the ascending aorta usually created?

Answer 108

posterior aortic wall interface with the left atrium

Question 109

Describe the findings and diagnosis

Answer 109

**Comet-tail artifact** * artifact is located parallell to the sound's beam and is a violation of time of flight and speed of sound assumpctions

Question 110

Describe beam width artifact also called section thickness or slice thickness

Answer 110

* occur distal to the focal zone where lateral resolution is least optimal * Two types: * related to slice thickness with superimposition of images from different planes * related to **suboptimal lateral resolution distal to the focal zone of the beam** * Similar to side lobe artifacts, they can appear as flaps in the aorta, catheters in the wrong position, thrombi in the LAA * occurs when the assumption that sound waves are infinitely thin throughout is violated * sound waves are 3D, so structures that are adjacent to the imaging plane but still within the imaging cone can still be displayed in the imaging plane

Question 111

What are several examples of beam width artifact (section / slice thickness)?

Answer 111

* Similar to side lobe artifacts, they can appear as: * flaps in the aorta * catheters in the wrong position * thrombi in the LAA

Question 112

What is one way to avoid / improve beam width artifact?

Answer 112

Focusing * adjustment of the focal zone of the beam narrows the beam width and the lateral resolution improves

Question 113

Define Snell's law

Answer 113

**Requires information on the angle of incidence of the US beam and speed of propogation of US in two different media** * describes the principle by which refraction of US occurs and contributes to the development of refraction type artifacts * Under normal conditions if the speed of US is the same in two media, the transmission angle will equal the incident angle

Question 114

Describe the findings

Answer 114

**Side lobe artifact -** in ascending aorta/aortic root

Question 115

What is the most common strong reflector that causes mirror image artifact?

Answer 115

lung

Question 116

Define side lobe artifact

Answer 116

**Image will appear at the wrong location, lateral to the true object location** * most of the energy emitted by the US machine is concentrated along a central beam * not all energy remains within central beam * some energy of the mechanical array transducer is also directed to the sides of the central beam (side lobes) that will return to the transducer * transducer assumes these have been generated from the central beam

Question 117

What is one way to avoid / improve side lobe artifact?

Answer 117

Decreasing gain and Applying Color Doppler

Question 118

What is the best way to avoid / improve refraction artifact?

Answer 118

Transducer: * repositioning * change in angle

Question 119

Describe refraction artifact

Answer 119

* Produced when the transmitted US beam is deviated from its straight path line (change in angle of incidence) as it crosses the boundary between two media with different propagation velocities * Sound beam bends --\> artifact displaying a "duplicated" structure * Refracted beam is reflectet back to the transducer --\> image in the wrong location * Examples: double aortic valve or double LV

Question 120

What is another name for mirror-image artifact?

Answer 120

crosstalk

Question 121

What is one way to help distinguish a LV thrombus from a near-field clutter artifact?

Answer 121

**Changing from fundamental to harmonic imaging** * helpful in reducing several types of artifacts * side lobe, grating lobe, reverberation, near-field clutter

Question 122

When should mechanical index be decreased?

Answer 122

when using contrast --\> to avoid excessive destruction of the bubbles

Question 123

What are artifact types that can be seen in the LV?

Answer 123

* Near field clutter * Reverberation (comet tail) * Range ambiguity * Shadowing (attenuation)

Question 124

A mirror-image artifact in two-dimensional echocardiography develops when:

Answer 124

* A **structure is located in front** of a highly reflective surface * resulting in a mirror-image copy of the structure * in a **deeper position**

Question 125

Describe the findings and artifact

Answer 125

**Range ambiguity artifact** * Resolved after increasing the depth

Question 126

Describe the findings and artifact

Answer 126

**Near field clutter** * Created from high-amplitude oscillations of the piezoelectric elements

Question 127

What can be done to improve / resolve near field clutter?

Answer 127

Improving near field resolution * Increase frequency (high frequency transducers) * Decrease depth * Change views * Contrast imaging * Harmonic imaging

Question 128

Describe the findings and artifact

Answer 128

**Beam width artifact (slice thickness)** * secondary to a calcified aortic valve/ascending aorta that is out of plane * All reflected signals encountered at any position or plane along the main two-dimensional ultrasound beam are displayed as if they originate from the same central and relatively thin plane * Strong signals at the margins of the beam or slightly out of plane create echoes that will be interpreted by the machine as arising from a point along the central beam, and the images will be superimposed

Question 129

Describe the findings

Answer 129

**Reverberation artifact** * Type B artifact * twice the distance from the LA posterior wall to the aortic posterior wall dimension * movement of artifact by M-mode parallels the movement of the aortic posterior wall and therefore does not have independent motion

Question 130

Describe the multiple artifacts present

Answer 130

* Comet tail * multiple comet tail artifacts caused by strong reflectors at the border of the diaphragm and the heart * Attenuation * Enhancement

Question 131

Describe the findings

Answer 131

ASD occludder in place - "**figure-of-eight**" artifact from the device

Question 132

Describe the findings and artifact

Answer 132

**Ghosting** * refers to color Doppler that is distorted beyond anatomic borders due to multiple reflections * can be seen as brief flashes that are inconsistent with physiologic or pathologic jets of regurgitation

Question 133

Describe the findings and type of artifact

Answer 133

**Reverberation** * artifact in the LAA (appears to be thrombus) caused by prominent coumadin ridge

Question 134

Describe the findings

Answer 134

**color Doppler artifact from - inflow cannula of an LVAD** * common artifact from continuous flow inflow cannulas related to the degradation of the color Doppler US singal * Absence of this type of artifact is a sign of pump dysfunction * Improve artifact: modified views

Question 135

What artifacts demonstrate: * artifact farther away from true object

Answer 135

* Reverberation * Mirror image * Comet Tail * Ring Down

Question 136

What artifacts demonstrate: * artifact to the side of the true object

Answer 136

* Refraction * Side Lobe * Grating Lobe * Beam Width

Question 137

What artifacts demonstrate: * artifact closer than the true object

Answer 137

Range ambiguity

Question 138

What artifacts demonstrate: * brighter

Answer 138

Enhancement

Question 139

What artifacts demonstrate: * artifact less bright

Answer 139

Shadowing

Question 140

What assumption is violated: * Beam Width

Answer 140

* **Narrow Beam** * **​**reflections return from a narrow transmit beam * **Central Axis** * **​**Reflections return form objects located on the beam's central axis

Question 141

What assumption is violated: * Side lobe * Grating lobe

Answer 141

* **Central Axis** * Reflections return from objects located on the beam's central axis **​**

Question 142

What assumption is violated: * Refraction

Answer 142

* **Central Axis** * **​**Reflections return from objects located on the beam's central axis ​ * **Straight beam** * **​**sound waves travel in straight line * **Speed of Sound** * **​**sound travels at a constant speed in tissue (1,540 m/s)

Question 143

What assumption is violated: * Propagation speed * Comet tail

Answer 143

* **Speed of Sound** * sound travels at a constant speed in tissue (1,540 m/s) * **Time of flight** * **​**sound takes a single round trip to a reflector and back

Question 144

What assumption is violated: * Shadowing * Enhancement

Answer 144

* **Proportional brightness** * ​reflections from an object are related directly to the reflective strength of that object

Question 145

What assumption is violated: * Reverberation * Near Field Clutter * Range Ambiguity * Mirror Image

Answer 145

* **Time of flight** * sound takes a single round trip to a reflector and back

Question 146

What assumption is violated: * Comet Tail

Answer 146

* **Time of flight** * sound takes a single round trip to a reflector and back * **Speed of Sound** * sound travels at a constant speed in tissue (1,540 m/s)

Question 147

Describe the findings

Answer 147

* Mirror image artifact below the heart * duplicate mitral valve (deeper) appears in the echolucent region --\> confirms that this is not related to an effusion or other pathologies

Question 148

Describe the findings

Answer 148

* **Comet-tail / reverberation** and **Side-lobe artifact** * Pacemaker wire in the RA * ​comet tail reverberation (arrowhead) below the wire and * side-lobe artifact extending in the radial direction

Question 149

Describe the findings

Answer 149

**Reverberation artifact** * reverberation artifact --\> mimicking a mass in the LA

Question 150

Describe the findings

Answer 150

**Reverberation artifact** * "stepladder" of reverberations (full arrowheads) * below a "multilayered" aortic calcification (arrow) * comet-tail artifact below strongly reflecting pericardium (empty arrows)

Question 151

Describe the findings

Answer 151

* **Side-lobe artifact** * **​**linear side-lobe artifact in the ascending aorta (arrow) due to a calcified sinotubular junction (arrowhead)

Question 152

Describe the findings

Answer 152

* **Side-lobe artifact** * **​**strongly reflecting pericardium --\> side-lobe artifact in the LA (arrow)

Question 153

Describe the findings

Answer 153

* **Acoustic shadowing** * **​**acoustic shadowing (asterisk) distal from an implanted MitraClip device (arrow)

Question 154

Describe the findings

Answer 154

* **Reverberation artifact** * **​**TEE images of LA * transseptal guiding catheter during pulmonary vein isolation procedure presenting with a series of closely spaced reverberations (arrowheads) due to reflections at the upper and lower side of the (hollow) catheter and one reverberation at twice the distance to the probe due to reflection at the transducer itself

Question 155

Describe the findings

Answer 155

* **Side-lobe artifact** * ​Defibrillator wire in the RV (arrow) * linear arc-like side-lobe artifact crossing anatomic borders (IVS). * should not be misinterpreted as dislocated (perforated) wire into the LV