Ultrasound Flashcards

Question

What are the problems with the pulse echo principle?

Answer 1

It assumes sound travels in a cone This is not the case in reality You do not know where the echo generating material lies

Answer 2

Using a narrower beam can give a better idea of where the echo came from You can get a better judge of distance Multiple small narrow beams provide more information

Answer 3

Propagation is in a straight line There is a thin beam Want a non diverging beam

Answer 4

Caused by the failing of assumptions | Machines are designed as if assumptions are true

Answer 5

When there is a change in the speed of sound Bone is much slower (4080ms-1) Air is much quicker (330ms-1) Works well in soft tissue where the speed of sound is similar in many tissues (1540-1580)

Answer 6

Speed = square root of: stiffness/density Sqrt k/p K can also be referred to as elasticity

Answer 7

Stiffness It is more important than density Stiffness has a 3x greater magnitude than density Ultrasound is stiffness mapping

Answer 8

Body is complicated and has multiple reflectors A certain fraction of energy is reflected at each reflector Some carries on and it reflected later There are many echoes per pulse Each echo can be separated as they do not arrive simultaneously

Answer 9

It will cast a shadow

Answer 10

It is the raw data seen by the machine not the operator It is not a 2D image It is the measured signal This can then be converted to a spot with a brightness proportional to the signal amplitude

Answer 11

Machine detects the signals Creates a spot with a brightness that is proportional to the signal amplitude Need multiple rows Need multiple transducers These are all in a line They are fired one at a time, to not confuse the signals

Answer 12

Use one direction to represent time rather than space Displays depth vs. time Can measure velocities, minimum and maximum dimensions It displays motion Exclusive to echocardiography

Answer 13

The largest signal (generally) will be from the first reflector Energy is lost as it passes through the tissue and because of reflection It would result in deep structures having a low signal without TGC It is controlled by the operator It can amplify echoes from specific depths

Answer 14

It is the transfer of mechanical energy from a vibrating source through a medium It is a mechanical wave and cannot travel through a vacuum It is a longitudinal wave

Answer 15

Deep structures would have low signal | Incorrect representation of the anatomy

Answer 16

Corrects for the loss of signal as the echo progresses It can create an artefact if done incorrectly Operator dependent

Answer 17

Creates an artefact | Noise is always present and it can create an echo where there isn't one by amplifying noise

Answer 18

1. Beam Spreading (diffraction) 2. Reflection 3. Scattering 4. Refraction 5. Absorption

Answer 19

Beam maintains width of source to a point and then it starts to diverge Divergence point can be calculated NF = r^2/wavelength This creates a near field and a far field Ideally want a long near field

Answer 20

``` NF = r^2 / wavelength NF = near field 2r = width of transducer ```

Answer 21

Increase the size of the transducer | Decrease the wavelength

Answer 22

Using a lens in front of the transducer to focus the beam It will focus at the focal depth Lens is electronic

Answer 23

This creates a narrower beam but creates a larger divergence after the focal point Degrades the quality of the image Sharpens the image at the focal depth

Answer 24

BW = F x wavelength / A ``` BW = beam width F = focal depth A = aperature of transucer ```

Answer 25

It degrades the quality of the image outside of the focusing depth Can focus at the wrong depth or use the wrong lens (poor operator) Operator dependent

Answer 26

Increase the aperature (size of transducer) | Decrease the wavelength used

Answer 27

It is essential for ultrasound It is not frequency dependent Reflection at a boundary depends on the change of acoustic impedance at the boundary Ultrasound signal is generated from boundaries It works well if 2 adjacent materials have similar Z values

Answer 28

Air has a very low characteristic acoustic impedance (Z) | Any gas will create a perfect mirror as all ultrasound is reflected back

Answer 29

``` Z = pc Z = acoustic impedance c = speed of sound p = density ```

Answer 30

``` R = reflected intensity / incident intensity R = (Z1-Z2/Z1+Z2)^2 ```

Answer 31

It occurs when a high proportion of the ultrasound beam energy is either reflected or attenuated by the target

Answer 32

Air/soft tissue interface Bone Calcification

Answer 33

The wave is reflected at an angle equal to the incident angle As the probe rotates it changes the image considerably

Answer 34

It is critical in the blood Erythrocytes are perfect scatters - redirecting energy in all directions but weak The proportion of energy scattered is proportional to frequency^4 Causes an exponential decrease in intensity

Answer 35

It occurs when the object is small compared to the wavelength It is highly frequency dependent

Answer 36

When there is a change of speed of propagation and the beam is bent from its original path There is no significant change of speed between soft tissue Not a big problem in ultrasound

Answer 37

It can occur when passing through muscle | Causes problems as the machine assumes the beam travels in a straight line

Answer 38

BAD! Transfer of mechanical energy to heat Direct conversion of energy to heat All ultrasound creates heat Heat increases linearly with frequency In soft tissue, absorption accounts for >80% of total intensity reduction Causes an exponential decrease in intensity

Answer 39

Frictional (visco-elastic) losses | Relaxation processes

Answer 40

Increased absorption | Increased heat

Answer 41

Occurs due to all interactions with matter | It is the loss of energy from the beam

Answer 42

Scatter | Absorption

Answer 43

The fraction of energy removed from a plane wave by the combined processes of absorption and scattering in unit path length it is tissue specific it is frequency dependent

Answer 44

1dBcm-1MHz-1

Answer 45

- Irregularities of the menstrual cycle - Congenital/structural abnormalities - Presence of a mass - Carcinoma (organ or origin or involvement of adjacent structures) - Presence of metastatic disease - Assisted contraception programmes - Intrauterine contraceptive device (IUCD localisation) - Screening program - Acute pelvic pain

Answer 46

Transabdominally | Transvaginally

Answer 47

Bladder filling Drink 1 pint of water before hand It allows you to look through the bladder to the uterus

Answer 48

Full bladder Longitudinal, transverse and oblique sections Contralateral technique Identify anatomical structures

Answer 49

Transducer is closer to the area of interest Can use high frequency Increase the definition of the structure Increased quality of image

Answer 50

The scan should demonstrate: - Normal anatomy/ varients - Assess size, outline, echotexture and echogenicity - Pathological findings

Answer 51

Age and menstrual status related appearances of the ovary and uterus

Answer 52

- Position - Size - Shape - Ultrasound characteristics of endo and myometrium - Centre of the uterus generates a linear echo - Uterus changes with cycle - Thickens from ovulation to menstruation

Answer 53

Using Doppler Blood flow to endometrium changes Can be useful in IVF

Answer 54

``` Position Size Shape Ultrasound characteristics Number and size of follicles Internal echo pattern of follicles They are small and hard to find - appearance changes with menstrual cycle ```

Answer 55

Largest during reproductive years | Shrinks in menopause

Answer 56

Initial ultrasound is on day 10-12 of cycle Can use grey-scale US to assess Can use Doppler to assess blood flow of endometrium and ovaries Can use sonohysterography - Injection of contrast medium to assess uterine cavity and tube patency

Answer 57

Location and size Internal consistency Borders Ascites and other metastatic lesions

Answer 58

Unilateral - adnexal or intrauterine | Bilateral - pelvoabdominal or not defined

Answer 59

Cystic - homogenous, sepataed, solid foci, multiple cysts, multicystic Complex - predominantly cystic or solid Solid - mildly, moderately or markedly echogenic

Answer 60

Well defined Moderately defined Poorly defined

Answer 61

Over 12 follicles Follicles are small and never fully develop Due to abnormal hormone levels

Answer 62

``` Relatively inexpensive Patient friendly Safe in experienced hands No radiation 1st line examination for some presentations ```

Answer 63

Scan in 1st trimester and at 20 weeks | Common practice - done in all pregnancies

Answer 64

``` Placental site and abnormalities Uterine abnormalities Detection of a pelvic mass Foetal position Control for invasive procedures Detection of foetal compromise - monitoring of foetal wellbeing Foetal growth monitoring Estimation of foetal weight Amniotic fluid volume Medico-legal issues Client-consumer expectations Viability ```

Answer 65

Pregnant women should be offered an early ultrasound scan between 10 weeks and 14 weeks to determine gestational age and detect multiple pregnancies Ensures consistency of gestational age assessment and reduce the incidence of induction of labour for prolonged pregnancy Crown-rump length should be used to determine gestational age - once this is over 84mm, should use head circumference

Answer 66

Gestational age Viability (foetal heart beat) Foetal number Detection of abnormalities

Answer 67

``` Mean gestation sac diameter Gestation sac volume Crown rump length 6-13 weeks Head circumference 13-25 weeks Femur length 13-25 weeks ```

Answer 68

Measurement of an anatomical parameter of a foetus | Estimate the age from the measurement

Answer 69

Reproducibility of the measurement | Correlation of the size to the age of the foetus

Answer 70

Can be used to look for intrauterine growth restriction Can use Doppler to assess the umbilical artery Done in high risk pregnancies

Answer 71

- Foetal anomaly screening (18-20wks) - Benefits outweigh risks - Reduce perinatal mortality by detecting malformations (requires a high level of expertise) - Reduce indications for induction of labour for post term pregnancy - Earlier detection of multiple pregnancies (improved management) - Earlier gestational age assessment

Answer 72

- Head and Neck (brain and nuchal fold - Down's) - Face (lip - cleft palate) - Chest (4 chamber heart, outflow tracts, lungs) - Abdomen (stomach, abdo wall (omphalocele), bowel, renal pelvis, bladder) - Spine (vertebrae - spina bifida) - Limbs - Uterine cavity (amniotic fluid, placental site)

Answer 73

Depends on the condition Anencephaly = 99% Cardiac abnormalities = 50%

Answer 74

- Detection of pregnancy at a very early age (4-5 weeks) - TV approach has increased sensitivity for detection of ectopic pregnancies - TV allows for detection of foetal movement from 5-6 weeks - Aids management of multiple pregnancies - Application of foetal biometry to reliable data - Aids management of complicated pregnancy - Diagnosis of congenital abnormalities

Answer 75

Linear Curvilinear Phased

Answer 76

Long flat front face Carotid artery Thyroid Breast

Answer 77

Curved face Fan Beam Obstetrics General abdominal

Answer 78

Flat face Small area Cardiac

Answer 79

It is difficult There is a small area for ultrasound due to the lungs and the ribs Small window requires a small transducer

Answer 80

Choose the field of view that matches the area of interest THEN choose the frequency. If it is superficial use a higher frequency Operator determined

Answer 81

Transrectal Transvaginal Intraoesophageal

Answer 82

2 x depth / speed 2D/C seconds

Answer 83

2 x N x D / c N = number of lines per frame D = depth c = speed of sound

Answer 84

C / 2xNxD c= speed of sound D = depth N = number of lines per frame

Answer 85

Decrease the number of lines in the scan | Decrease the depth

Answer 86

20-25fps | If it is lower you get a jerky image

Answer 87

``` N = C / FR x 2 x D N = 1540 / 25 x 2 x 0.1 N = 308 lines ``` This will give a poor image - there is not enough time to get an adequate number of lines

Answer 88

Can use false frames | Only if the image is not moving quickly

Answer 89

Liver, cardiac, kidney | when the object is moving quickly

Answer 90

Uses linear interpolation - Can miss very small features - Must not detect a depth that is too much as you are throwing away information

Answer 91

It sends sychronising pulses around the system It instructs the pulses of the ultrasound Each pulse corresponds to a command to send a new pulse from transducer It determines the pulse repetition frequency It communicates with the transmitter,TGC generator and Beam controller Need to wait for echo to return before sending out the next pulse

Answer 92

PRF The rate of ultrasound pulse generate (kHz) NOT US FREQUENCY (MHz)

Answer 93

PRF = 1 / time per line PRF = speed / 2 x depth

Answer 94

Responds to clock commands by generating high voltage pulses to excite the transducer It is housed very closer to the transducer (likely to be within it) It causes the transducer to vibrate/oscillate to create the sound

Answer 95

Housed very close to the transducer (likely to be within in) | This reduces time and ensures there is no loss of voltage

Answer 96

Clock instructs the transmitter Transmitter creates a voltage Voltage creates an oscillation in the crystal

Answer 97

Converts analogue signal into digital signals for further processing Once digitised, everything else is software Receives analogue signals from the transducer Transmits digital signals to the signal processor

Answer 98

- Be fast enough to cope with the highest frequencies - Have sufficient levels to create an adequate grey scale e.g. 1024 - Be higher than frequency so as not to lose information - Can be fast or have lots of levels

Answer 99

It is different for each manufacturer. The digital signal from the ADC is passed to the signal processor.

Answer 100

TGC Application Overall gain Signal compression Demodulation

Answer 101

Time gain control | Applying different gains at different depths set by the operator

Answer 102

Treats all echoes equally as all echoes are small and need extra amplification

Answer 103

Returning echoes have a wide range of amplitudes and these should be represented by different grey values Signals converted to a grey levels

Answer 104

Largest signal level below saturation / smallest signal level above noise.

Answer 105

It is the ratio of the largest to the smallest signal Usually expressed in decibels Range 10uV to 1V

Answer 106

Saturation - it a signal goes above the saturation point it is viewed as the same colour as the maximum

Answer 107

Noise - signal will not be displayed if it is below noise

Answer 108

It is a relative unit 1 dB = 10log10 (p1/p2) x compared to y

Answer 109

Power is proportional to voltage squared 1dB = 10log10 (v1/v2)^2 1dB = 20log10 (v1/v2)

Answer 110

Generally around 100dB There is a massive ability to distinguish different sounds Typical monitors have DR = 25dB

Answer 111

They are converted to a grey scale Lose a lot of information Displays are not good enough to display all sound levels Brains cannot distinguish all of the subtle differences

Answer 112

Linear | Transfer curves

Answer 113

Divide range into equal segments in a linear fashion | Problem: all small signals are assigned a grey scale level one and you lose all contrast resolution for small echoes

Answer 114

Assigning grey levels to echo amplitudes | Optimise the curve to the clinical requirement

Answer 115

Image Curve 1 - using most grey scales for lower echoes Curve 3 - lost information for small echoes and use more grey scales for higher echoes Machines have presets Loads curve that is best for a particular application Different curves for different manufacturers

Answer 116

X and Y are positional information and this comes from the beam controller Z value is the grey scale level

Answer 117

Takes Z (brightness) signal from the processor Positions it in the image memory using the X and Y information from the beam controller Assembles an image for each frame Presents assembled image to display

Answer 118

100-200 images/frames on a cineloop

Answer 119

X value - depth determined by timing and speed of sound assumption Y value - distance from the edge of the array at which the pulse was launched

Answer 120

Anything which is done to the signal prior to storage in the image memory It is DESTRUCTIVE (cannot be undone) Includes TGC, depth scale, compression

Answer 121

Anything which is done to the image/signal AFTER storage in the image memory It is non-destructive Includes: alpha numerics, calipers, black and white inversion, read zoom Can be scaling or transfer function

Answer 122

In any frame, some of the information displayed will be noise It removes unwanted signal and decreases the noise errors It will pick up any noise in the environments Taking the maximum or minimum value (rather than averaging) will emphasise noise.

Answer 123

electronics, acousitc, environmental | Noise is expected in every frame because of the random nature

Answer 124

Decreased noise errors

Answer 125

Increase time Slower to respond to genuine changes Lose some information relating to movement Trade off between frame rate and noise reduction (incorporated into machine presets)

Answer 126

Sends out short ultrasound pulses when excited electrically | Detects returning echoes and presents them as small electrical signals

Answer 127

Decrease near field | Increase lines

Answer 128

Partial solution Fire several elements together Electrically connect a block of transducers 1 pulse = several transducers fire Move down by one element e.g. 1-7 then 2-8 etc. Repeat but block size is maintained Mimics the effect of a large source but produces multiple lines SYNTHETIC APERTURE

Answer 129

synthesises an artificially larger transducer Increase near filed as N^2 Usual element size is 1mm and this creates a short NF Extends this

Answer 130

It introduces delays to compensate for the extra path length of the outer elements Increases the delay at central transducers At an arbitrary point, signals will arrive at the same time You choose that point This is done on transmission and reception Same effect as a lens Increases the quality at a specific depth

Answer 131

Waves from outer elements have greater path lengths - therefore signals do not arrive simulateously at the target - Reflections from the target do not arrive at all elements at the same time - Blurring on way in and way out

Answer 132

``` Can direct beam off all axis Can use all the elements each time Can fire beam at any angle by changing delays No stepping along the array Small sources ```

Answer 133

Focusing makes the image worse at other depths Instead of moving the array down - send out beams at different time delays Start collecting echoes after the cross over point Multiple beams Creates multiple images with various foci which are then combined

Answer 134

Increases the quality of the image | Increases time

Answer 135

Operator needs to put in as many zones as possible but keep the frame rate high enough to detect movement Many in breast, few in cardiac

Answer 136

Linear | Curvilinear

Answer 137

Smaller beamwidth Depth of focus is reduced Determined by the manufacturer

Answer 138

Axial Lateral Slice thickness

Answer 139

It is the resolution in the direction parallel to the direction of the beam The resolution along any point of the beam is the same Depends on pulse length

Answer 140

Increasing frequency = decreased wavelength | This gives increased axial resolution as there are shorter pulses

Answer 141

Short pulse

Answer 142

Increase frequency Decrease wavelength Decrease the number of cycles in a pulse

Answer 143

lateral resolution is defined as the ability of the system to distinguish two points in the direction perpendicular to the direction of the ultrasound beam It depends on beam width The object is viewed as wide as the beam width

Answer 144

Image Object is viewed as wide as the beam width Increasing beam width = decreased lateral resolution

Answer 145

``` Shape and size of transducer Depends upon the focusing BW = F x wavelength / A F = focal length. A = aperture As frequency goes up, the wavelength goes down = beam width goes down = lateral resolution increases ```

Answer 146

Decrease beam width by: Increasing frequency Increasing the size of the aperture

Answer 147

It depends on the thickness or height of the beam Normally poor as there is no electronic focusing Decreases as frequency increases Usually the worst resolution

Answer 148

1.5/2D arrays improve focusing and resolution Can focus the beam in 2 planes Can send a beam out in any direction

Answer 149

The technique of using ultrasound to measure flow. Have increase in frequency when direction is towards observer and decrease when it is away.

Answer 150

When either the receptor or the generator is moving relative to the other If there is no movement the frequency emitted it equal to the frequency received

Answer 151

Moving source - stationary observer Increase pitch Increase frequency Waves are squashed in the direction of travel.

Answer 152

Decrease frequency | Waves are stretched

Answer 153

Also get a Doppler shift. | If the person is moving towards the source then it picks up waves more rapidly causing an increase in frequency

Answer 154

Motion towards = Increase frequency | Motion away = decrease frequency

Answer 155

- Sound is transmitted to the blood and will irriadiate the RBCs - They are moving - The frequency the RBCs receive different to sent out - They scatter the signal in all directions - The backscattered shifted signal is sent out in all directions First there is a stationary source (transducer) and moving receiver (RBC) Then the RBC acts as a moving source and the transducer becomes the stationary receiver

Answer 156

They do not cancel each other out - it is doubly shifted.

Answer 157

Doppler shift (delta f) It is the difference between the received frequency (fr) and the transmitted frequency (ft) Change in frequency of the echo due to the motion of the target

Answer 158

``` cos(angle) x 2 x ft x v / c ft = transmitted frequency c = speed of sound v = target speed 2x due to the double Doppler shift angle = angle between the beam and flow ```

Answer 159

No Doppler shift occurs if it hits at 90 degrees Ultrasound is generally done at 90 degrees to not get a signal from blood Maximal Doppler shift is at 0 or 180 degrees Need to know the angle used

Answer 160

- Superimpose the Doppler information on top of the underlying grey scale image. - Use colours to represent the Doppler shifts

Answer 161

- Repeated firing along one scan line - Compare lines in consecutive pairs - Divide each line into segments - Compare segment by segment - Use frequency content of each segment - 6 or 8 samples down each line - Look at the similarities and differences between the pairs - If the segments are identical = no Doppler shift

Answer 162

Superimposed colours on greyscale image Doppler shift frequency is not displayed Displays PHASE Measure phase difference

Answer 163

Frequency = rate of change of phase = Speed

Answer 164

Colour indicated direction: Blue Away Red Towards Blue - movement away from transducer Shade = velocity Variance - how wide spread are the velocities? Colour options: hue, brightness, saturation

Answer 165

Green/yellow

Answer 166

- Determines whether to display colour or grey scale - If the grey level is large enough, a colour is not put there - If the grey level is less than the threshold value then display colour - The decision is arbitrary - If there is a large signal e.g. from a boundary then you want it to be displayed

Answer 167

Blood/tissue discriminator | The discrimination point is determined by the operator - Doppler priority

Answer 168

Autocorrelator

Answer 169

Operator places a box over the region of interest This instructs the machine to look in that area to determine Doppler effect Keep the box as small as possible

Answer 170

Increase size of box = decreased frame rate due to increased lines

Answer 171

More sensitive than normal colour but does not give the velocity information

Answer 172

In Colour - the values collected are sorted into velocity bins. Anything below noise will not be detected - any components are not represented strongly will not be detected Power Doppler - all values placed into one bin. The one value bin is way above the noise level

Answer 173

- Better signal to noise ratio - Better at picking up low volume flow - Better for peripheral areas and areas of low flow e.g. stenosis - Powerful sensitivity - Insensitive to Doppler angle

Answer 174

- Gives no velocity estimate - may not have directional discrimination (no idea if negative or positive flow) - has no measure of turbulence - no quantification

Answer 175

Suppresses blood flow, looks at the movement of vessels. It is colour Doppler set up slightly differently. ``` Turn down Doppler gain Use low pass filter - to supress blodd Removes the wall thump filter Displays colour on vessel walls Detects tissue motion ```

Answer 176

Used for low velocities | Used to view the vessel walls

Answer 177

Vessels move slower than blood If the velocity is less than X then remove Applied by this high pass filter Suppresses detail from blood flow.

Answer 178

It is the purest form of Doppler Permanently emitting and receiving - separate send and receive transducers are used It provides a snap shot of what is happening in the vessel

Answer 179

Simple Cheap High quality spectral information available

Answer 180

Stationary targets e.g. organ boundaries | Slow moving large targets e.g. vessels walls

Answer 181

Need to filter out clutter signal

Answer 182

Blood moves with a range of velocities The velocity distribution changes with time Flow is pulsatile You get different appearances at different points in the cardiac cycle

Answer 183

It displays the range of velocities along the x axis It displays the delta f (Doppler shift frequency) along the y axis At each time point there is a range of velocities present and their relative intensities The orange/brown colour is used to display intensity It details systole and diastole Shows peak velocity

Answer 184

Shows lots of detailed information Each artery has a different Doppler spectrum Very sensitive to pathology but requires an expert

Answer 185

Ignoring the angle | Changing angles changes the spectrum

Answer 186

``` Do not know vessel angle May have overlying vessels Do not have an image No depth discrimination Requires an expert Need to be certain of anatomy ```

Answer 187

Need to be certain of anatomy 1. Check for vessel patency in vascular surgery 2. Foetal heart detection 3. DVT detection

Answer 188

``` Uses long pulses NOT continuous waves Approximately 6-7 cycles Have gating to select depth Can have an associated image Pulses give depth information ```

Answer 189

``` Everything is compromised Poorer axial resolution Can distinguish overlying vessels Too short for frequency information but also lose spatial information Can get a pressure ```

Answer 190

Undersampling can lead to a misleading image | Limit for aliasing = Nyquist theorem

Answer 191

Less than PRF/2 | If PRF = 1kHz, can’t detect doppler shift greater than 500Hz

Answer 192

p1-p2 is approximately equal to 4V^2 p1-p2 = pressure gradient v = peak velocity at narrowing If you can measure the peak velocity, can non-non-invasively calculate pressure change over a pathology.

Answer 193

Depth information Can combine with an image Good spectral infromation

Answer 194

Aliasing Need to know where to look Can only look at one place at once

Answer 195

Is it characterised by high pressure gradients across the narrowing Use colour doppler first then guided pulse doppler to get spectral information Using pulse doppler can get pressure and the pressure difference is related to the density and velocity of fluid movement in the vessel.

Answer 196

They are a resonant device They have a natural frequency The thickness of each element in the housing depends on the wavelength Range from 3-10MHz

Answer 197

Thickness = wavelength / 2

Answer 198

Increase frequency

Answer 199

``` Backing material Electrodes - the transducer has electrodes evaporated onto the transducer. Transducer Electrodes Matching material ```

Answer 200

Dampens the resonance | Allows you to control the pulse (very short) to get better axial resolution

Answer 201

Increase axial resolution

Answer 202

Absorbs some of the sound to dampen oscillation | Needs to allow sound in readily but stop it leaving

Answer 203

Needs to be a good absorber Needs a high absorption coefficient Needs to have a similar Z value to that of the transducer ZT= ZB

Answer 204

It makes the transducer less efficient | Heats during use

Answer 205

Gets the energy out of the transducer and into the patient

Answer 206

Halfway between the Z of the patient and the transducer Zm = SQR (ZT x Zpt) ZM = acoustic impedance of matching material ZT = acoustic impedance of transducer Zpt = acoustic impedance of patient

Answer 207

Unknown | Different in different manufacturers

Answer 208

to have a high value of attenuation to be well matched to Z of PZT but it reduces sensitivity and efficiency

Answer 209

to have a Z value matched to transducer and patient | this will always be a compromise

Answer 210

approximately 1/4 of the wavelength

Answer 211

Have other materials included to reduce Z value and increase efficiency Allows for use of multi-frequency transducers Capable of being used away from optimum frequency

Answer 212

Transducers for CW only do not need a backing material - does not use pulses This makes them very efficient and sensitive.

Answer 213

Involves breaking down a signal into its component parts.

Answer 214

image One fixed frequency Fixed amplitude No width in Fourier analysis - single line

Answer 215

Varies in amplitude Contains a range of frequences Complicated in shape Fourier analysis shows a spread of frequencies

Answer 216

image similar to continuous wave but there is a spread of frequency Narrower range of frequencies than short pulse

Answer 217

large range of frequencies | wider bandwidth

Answer 218

Increase pulse length = decrease bandwidth

Answer 219

High frequency components are attenuated MORE than low frequency components - Tissue attenuation is frequency related - As it travels through the tissue it changes - Change in frequency content and change in shape of pulse Image

Answer 220

Reduction in bandwidth Decrease in central frequency Same process as beam hardening

Answer 221

Wideband Good spatial resolution Increased axial resolution due to wide bandwidth

Answer 222

narrowband Medium spatial resolution Better control of frequency (therefore better for Doppler)

Answer 223

Narrowband Poor spatial resolution Pulse wave 7-8 cycles Decreasing bandwidth from B mode and colour.

Answer 224

No pulse No axial spatial resolution Image 250

Answer 225

- As the beam is travelling through tissue it is changing shape - Momentarily there are changes in pressure and alters the tissue and the speed of sound - Slope rotates clockwise - Tissues causes non-linear distortion of the beam - High pressure = tissue compressed, higher velocity - Low pressure = tissue expanded, lower velocity

Answer 226

High energy/ amplitude of the beam | Distortion increases on the return journey back to the transducer

Answer 227

Image | Peaks in distorted are multiples of the original frequency e.g. f, 2f, 3f

Answer 228

Peaks that are multiples of the frequency f, 2f, 3f etc. of the original frequency Part of the wave is coming back at higher than the frequency sent out

Answer 229

Send out a wave at frequency f Measure frequency returned at 2f Harmonics are generated in the tissue - creates better resolution

Answer 230

- Reduces clutter due to artefacts (a lot of clutter is low amplitude and doesn't contain much 2f) - Improved spatial resolution - Increased contrast

Answer 231

Reduced dynamic range | Reduced penetration

Answer 232

2 main methods - filtering - pulse inversion Each manufacturer does it slightly different

Answer 233

- Divide the bandwidth into 2 and use the low end for transmission and the upper end for reception - Makes smarter use of bandwidth available - Excite at below the resonant frequency - Put in a filter and filter out anything but 2f

Answer 234

Bandwidth is reduced therefore pulses are longer Degrades axial resolution Improved lateral resolution at the expense of axial. (Axial is better so can lose a bit more)

Answer 235

- Send out 2 pulses, one of which is the inverse of each other - Add them together - Expect A+-A = 0 if they are symmetric - However distortions are not symmetric and harmonic is left behind - Assume symmetry - not true to do non-linear propagation. - The inverted pulse is distorted differently to the original - Pulses cancel out but the echoes do not - Summing up of echoes gives 2f

Answer 236

- Uses short broadband pulses - No degradation to axial resolution - Frame penalty - have to send out 2 pulses

Answer 237

Both work well and achieve objectives with different costs - If frame rate is a problem do not use pulse inversion - Cardiac uses filtering - Most others will use pulse inversion and accept a slower rate

Answer 238

It makes an area visible that was not previous visible | They attempt to map function in a way that raw imaging does not

Answer 239

Small encapsulated gas bubbles. - Injected into the blood stream - Administer small amounts in a controlled environment - Give a large echo

Answer 240

1. They have a strong acoustic impedance mismatch (Z in air is low, low density and speed of sound. Relative to soft tissue there is a large difference) 2. At some point frequencies are RESONANT and this provides further enhancement (x1000) (If the bubble is hit with the right frequency you will get a large increase in the quality of the signal 3. Have more non-linearity than soft tissue and can therefore be detected using harmonic imaging

Answer 241

- Agents travel through a peripheral vein through the blood by encapsulating - It is stabilised by an outer shell - Use heavy inert gases to increase life time

Answer 242

It is stabilising | Creates a longer half life

Answer 243

Creates an extended bubble life | Less diffusion out of the shell

Answer 244

1-6 micrometerres

Answer 245

Air Octofluoropropane Nitrogen

Answer 246

Albumin Lipid/surfactant Polymer

Answer 247

Albunex Definity Sonovue

Answer 248

Pressure in the pulse

Answer 249

Linear oscillations Non-linear oscillations Transient scattering/ bubble destruction

Answer 250

Occurs at pressures

Answer 251

- Occurs at pressures above 50kPa - Arise primarily from contrast agent in blood as the bubbles exhibit stronger non-linearity - Harmonic generation is minimal in tissue - Work in this area when working with contrast agents

Answer 252

Occurs at pressure over 1MPa | As intensity increases, the shell becomes leaky and will eventually burst releasing free microbubbles

Answer 253

Mechanical index | Related to the pressure of the singal

Answer 254

0.006-0.06 MI (3MHz) | 10-100kPa

Answer 255

0.06-0.6 MI (3MHz) | 100kPa-1MPa

Answer 256

0.6-6 MI (3MHz) | 1-10MPa

Answer 257

- Bubble size - Gas content - Encapsulation - Administration - Detection

Answer 258

``` f = 3.3/r r = bubble radius (micrometres) f = resonant frequency (MHz) ``` Encapsulated bubbles are more complex

Answer 259

``` f = 3.3/1 f = 3.3MHz ```

Answer 260

Higher resonant frequency

Answer 261

Nothing over 10 micrometres | Large bubbles will be trapped in the lungs and cause emboli

Answer 262

Normally: air or heavy gases like perflurocarbon or nitrogen. - Heavy gases are less water soluble so they are less likely to leak out from the microbubble to impair echogenicity - Heavy gases last longer in circulation - Choice does not matter acoustically - Needs to be non-toxic

Answer 263

- currently: albumin, galactose, lipid or polymers - The more elastic the material the more acoustic energy it can withstand before bursting - BUT stiffer shells generate more harmonic signals - Behaviour on compression is different from behaviour on expansion - If the pressure is too great the surface tension can't support the bubble and BUCKLING occurs (depends on shell material)

Answer 264

Normally venous either bolus or slow transfuction - Have multiphasic response - Can use a destruction pulse to temporarily clear a region and monitor re-population (useful for diagnosing metastases)

Answer 265

Can watch tissue or organ dynamics | Plot wash in and wash out curves

Answer 266

Look at steady state response | Image over several frames to identify regions of high/low uptake

Answer 267

Use harmonic content of back-scattered bubble Use enhanced Doppler signal since the bubble is moving and backscatter from the bubble is larger than from RBC

Answer 268

- Study of transcranial and neck vessels - Contrast echocardiography - Liver imaging to detect portal hypertension and thrombosis - Oncology

Answer 269

- Microbubbles are targeted with ligands that bind to certain molecular markers that are expressed by the area of imaging interest or by direct binding to the cell of interest - Microbubbles travel through the circulatory system, finding respective targets and binding - If a sufficient number bind they become visible - Place part of a binding pair on the surface of the bubble

Answer 270

- Tumour marker - Attach a chemotherapeutic agent in/on the bubble and use high energy ultrasound to burst the bubble - Agent is released and enters tumour via sonoporation

Answer 271

- Life time in blood stream - Adhesion/specificity - Unwanted immune response - Toxicity - No toxic biproducts

Answer 272

- Safe - Well tolerated - Relatively low cost - No ionising radiation - Few technical limitations - Patient friendly (no claustrophobia) - Metallic implants not a problem - Better for real time dynamic studies

Answer 273

- Highly operator dependent - Requires in depth anatomy knowledge - Limited in joint assessment (intra-articular not viewable) - Bad for knee and hip

Answer 274

7-17MHz linear transducers High frequecy Can use curvilinear if you need to see a mass or deeper structure

Answer 275

- Panoramic - wide field of view. Builds up as you go across - Dual screen (allows you to compare one normal image with pathological sample) - Power/colour Doppler (is sensitive and is good in rheumatology. A lot of masses will have vascularity. Can tell if pt has synovitis.)

Answer 276

``` Joints Tendons Muscles Bones (cortical surface) Ligaments Bursae Nerves ```

Answer 277

Attach muscle to bone Fascicles type 1 collagen, orientated mainly parallel to the long axis Covered in paratenon and epitendineum If they need more movement they are in the synovial sheet

Answer 278

echogenic fibrillar structures multiple parallel lines in longitudinal section multiple dots on transverse section

Answer 279

thin echogenic fluid containing structure that surrounds the echogenic tendon

Answer 280

Looks very similar to ligaments and tendons Facicles are more spread out Hypoechoic group of fascicles Have perineurium and epineurium (echogenic)

Answer 281

Muscle fibres are grouped into fascicles separated by septa of fibroadipose tissue (perimysium) Whole muscle enclosed in a fascial sheath (epimysium)

Answer 282

Transverse perimysium is seen as dot echoes or short lines scattered throughout hypoechoic background Large intramuscular septa are echogenic Produce a reticular pattern Intermuscular septa are brightly echogenic

Answer 283

Muscle alters shape and becomes hypoechoic and increased angulation of echogenic septa

Answer 284

Imaged at stress and in extension. It can look pathological if not State alters echogenicity

Answer 285

Cartilage Synovial fluid Joint Capsule Fat pad

Answer 286

Anisotropy It can make tendons look pathological This is the effect that makes a tendon appear bright when it runs at 90 degrees to the ultrasound beam, but dark when the angle is changed. Need to scan at appropriate angle

Answer 287

- Rheumatoid arthritis and joint disease– management of the disease, small joint assessment - Soft tissue masses, lumps and bumps, hernias - Sports medicine – muscle tears, sprains, athlete rehabilitation - Trauma – muscle tear, tendon rupture - Age related degenerative changes – rotator cuff disease, osteoathritis

Answer 288

- Tendon tears - Tendinosis - Tenosynovitis - Joint effusions/bone erosions from RA - Bursitis, ganglion cysts, lipoma, muscle tears, nerve masses, ligament sprains History taking can aid diagnosis

Answer 289

- Joint aspirations - Therapeutic steroid injections - Biopsy of masses - Nerve block

Answer 290

Cavitation Microstreaming Heating

Answer 291

- Concerned with activity of small bubbles when exposed to ultrasound - Most significant when using large pressures and low frequencies - Important close to gas collections (lung)

Answer 292

- Dissolved gases in the surrounding area diffuse into bubbles under positive pressure (positive half cycle) - Negative half cycle = expands and some gas diffuses out - Negative half cycle is more efficient at moving gas - In a complete cycle the bubble will grow and have less gas within it At the end of the pulse everything goes back to normal (not a problem with a short pulse) In a long pulse, pressures become so great that the bubble cannot be supported by surface tension and will collapse inwards - dangerous

Answer 293

It does not take place in vivo with diagnostic US levels. | Oscillations at lower levels can cause change in micro-circulation and alter cell permeability

Answer 294

All procedures causes heating due to the deposition of energy. Normally most significant in pulsed or colour Doppler.

Answer 295

Exposure is either continuous or with long pulses | There is also repeated firing down one line

Answer 296

Soft tissue - bone interfaces | Strong reflection and as a result lose a lot of energy here.

Answer 297

Depends on the time averaged intensity and/or power.

Answer 298

MI - mechanical index | TI - thermal index

Answer 299

Mechanical index Risk of cavitation damage Advised to keep below 0.3 (no adverse data below 0.3)

Answer 300

Thermal index | Risk of thermal damage

Answer 301

MI = p/ sqrt (f) ``` p = peak negative pressure (MPa) f = frequency (MHz) ```

Answer 302

TI = power emitted/W deg Wdeg = power required to raise temperature by 1oC Ratio of total power to Wdeg Keep below 0.5 Any increase in temperature of a body part by 1.5 degrees is fine

Answer 303

No one has ever shown to have been damaged by a diagnostic ultrasound examination

Answer 304

BMUS website

Answer 305

There is a possibility of minor damage to the neonatal lung or intestine. Try to reduce exposure time as much as possible

Answer 306

There is a risk of cavitation if an ultrasound contrast agent is being used containing micro-spheres. Risk increases with MI values above this threshold

Answer 307

Scanning of an embryo or foetus is not recommended however briefly

Answer 308

``` TI = 0.7 max time = 60min TI = 1.0 max time = 30min TI = 1.5 max time = 15min TI = 2 max time = 4min TI = 2.5 max time = 1min ```

Answer 309

- Use maximum receiver gain and minimum output power to achieve diagnostic image (gain does not affect MI or TI) - Avoid pulsed Doppler in early pregnancy in early pregnancy unless critical - Minimise dwell time - Do not perform scans with no clinical justification - Ensure that operators at adequately trained

Answer 310

Apply stress (cause) and measure strain (effect)

Answer 311

Imaging technique for soft tissue stiffness assessment An imaging technique whereby local axial tissue strains are estimated from differential ultrasonic speckle displacements

Answer 312

Changes in elasticity are generally correlated with pathological phenomena Equivalent to palpation

Answer 313

``` Stress = F/A F = force A = area Stress = pressure ```

Answer 314

Change in length/original length Fractional change in length of the material

Answer 315

E = Stress/Strain Units = same as those of pressure Young's modulus = stiffness

Answer 316

Abnormalities have different Young's modulus values Increase in tumours

Answer 317

1. Generation of a low frequency vibration 2. Imaging 3. Elasticity estimation

Answer 318

Image of tissue - store Push transducer harder - store image Comparing the 2 images will show resultant strain due to tissue deformation

Answer 319

A fully compliant stand-off later (of known EM) is introduced It allows free passage of ultrasound waves Simultaneous measurement of strain in this layer enables calculation of axial stress distribution

Answer 320

1. A scan performed without compression 2. Slight compression with the probe 3. Cross correlation - compare the 2 A scans. Produce a map along the A scan and repeat for different lines

Answer 321

- Manual static pressure - Internal pressure (cardiac, respiratory - useful for liver can use breathold) - External dynamic pressure (mechanical movement of the transducer) - External dynamic pressure (push pulses - can use ultrasound internally to cause stress)

Answer 322

Autocorrelation of before/after A lines Autocorrelation of before/after frames Measurement of shear wave propagation

Answer 323

1. User dependent - some people will push more than others. 2. Stress applied not reproducible 3. Indirect stiffness measurement 4. Difficult interpretation 5. Need direct access e.g. breast, prostate

Answer 324

Electrodynamic transducer rhythmically pulses the ultrasound transducer on the surface of the skin - very heavily used in heptaology

Answer 325

- Can confirm cirrhosis - Hard to pick up different types of cirrhosis - Can't differentiate mild and significant fibrosis - There is a stretch in the axial direction

Answer 326

- Deformation of tissue - Greater differentiation between normal and abnormal - Send out high MI pulse - Fire in succession at different depths - Causes rapid expansion of the tissue in all directions - Creates a lateral pressure - Shear waves travel slowly 3-4ms-1

Answer 327

- Multiple points in depth are emitted with a focused US beam - A shear wave front is created which corrects the fast attenuation - Emitted pulses are triggered at a speed greater than the speed of the shear wave propagation - Shear wave front creates a Mach cone

Answer 328

Compressive | Shear

Answer 329

Compressive wave velocity is nearly uniform in soft tissue and is observed and sonic and ultrasonic frequencies c^2 = K/p ``` C = speed K = bulk modulus p = density ```

Answer 330

``` Velocity varies strongly in the soft tissue - only observed at sonic frequencies (less than 1 kHz) C^2 = G/p C = speed G = shear modulus p = density ```

Answer 331

Much quicker Higher frame rate Combines shear and high frame rate and could cause a bit change Acquired data from large zones rather than multiple lines

Answer 332

- Don't know frequency content of the propagating shear wave | - Do not know optimum frequency at which to probe the mechanical properties of the tissue

Answer 333

- artefacts that arise within the patient - Artefacts that arise within the equipment - Artefacts that are operator induced

Answer 334

- Beam axis is straight - Pulse only travels to targets that are on the beam axis and back to the transducer - The beam is thin (has negligible lateral width and slice thickness) - the speed to sound is constant - the attenuation in tissue is constant

Answer 335

- Echoes appear when structures are not really there - No echoes appearing where there is a structure - Size, shape and location of structures is inaccurate

Answer 336

- Not real - Missing - Improperly located - of incorrect brightness - Incorrect size - Incorrect shape

Answer 337

- Acoustic shadowing - Acoustic enhancement - reverberation (comet tail) - Refraction - Edge shadow (refraction) - Mirror image - Speed of sound artefacts

Answer 338

When there is a high impedance mismatch between structures aligned along the axis of the beam, almost total reflection can occur. e.g. soft tissue and ribs - no echo is retrieved from the areas distal to ribs It will also occur when the beam passes through a structure that is highly attenuating e.g. lesions, cirrhosis. Most of the sound energy is lost through absorption and little detail can be seen distal

Answer 339

- By adapting the scan angle (best) - Compound imaging - In most instances, it is possible to interrogate areas posterior to the shadowing structure

Answer 340

When the sound beam passes through a structure that is of low attenuation. The echoes posteriorly appear brighter than surrounding tissue with the loss of information - Saturation of the image (turn down gain, change TGC)

Answer 341

This occurs where the sound pulse bounces back and forth between 2 highly reflective surfaces So much energy is reflected from the boundary and it is reflected back off the transducer and back into the material. Machine assumes travel in straight line Get equally spaced false series reflectors.

Answer 342

This is produced by a short pathway reverberation of the pulse between structures of high impedance mismatch. Pulse travels back and forth between the closely spaced reflectors producing a short time delay between each echo.

Answer 343

Comet tail is a type of reverberation Comet tail occurs between 2 reflectors rather than between reflector and transducer

Answer 344

Occurs at the boundary between 2 media where the speed of sound is different - When the beam hits the boundary at an angle, it is bent away from original course - Can lead to misleading appearances Doesn't happen very often

Answer 345

Can look like twins due to refraction at abdominal muscles

Answer 346

- Curved interface at an oblique angle such as the edge of a cyst or soft mass within a solid tissue - Beam transmission is diverted (refracted) to a new direction - Shadow is caused by few echoes returning to the transducer from the original line of site

Answer 347

- Occurs due to specular reflection at a large smooth interface - High acoustic impedance mismatch - Reflected beam encounters a scattering target - Echoes from the target return via the same path to transducer - Mirror image seen behind the smooth reflector Strong reflector is meeting the beam at an angle - sound no longer travels in straight line (right angles) and the target is placed on straight line

Answer 348

Where the speed of sound in tissue between the target and transducer is higher than 1540ms-1 the target will appear closer to the probe than it really is. If it is slower it will appear further away

Answer 349

Measurement/size errors For most purposes displayed size changes +/- 5% not noticeable May need correction

Answer 350

As a result of a number of false assumptions: - It assumes that any returning echo will have originated from the central axis of the beam - It assumes it has negligible lateral and slice thickness

Answer 351

Width along scan plane Varies with distance from the probe Narrowest in the focal region Dependant on the type of focusing used

Answer 352

2 reflectors placed side by side within the beam will be resolved only if the spacing between them is greater than the affective beam width

Answer 353

Width of the beam at right angles to the scan plane

Answer 354

Causes overlap of echo information from structures that lie outside the scan plane. Most noticeable in small liquid filled areas. They can have echoes from surrounding areas instead of being echo poor.

Answer 355

Spurious signals that arise from echoes induced by ultrasound transmission outside the main beam Degrades the image Inhibits detection of weak echoes.

Answer 356

These are side lobes which can occur on any probe having regular spaced elements Weak replicas of the main beam at up to 90 degrees on each side of the beam Contribute spurious echoes to the image and effectively widen the beam in the scan plane. Reduces lateral and contrast resolution Reduced by use of harmonic imaging

Answer 357

Use harmonic imaging

Answer 358

- Misuse of controls such as overall gain and TGC - Movement (FR not fast enough to show movement smoothly - Caliper inaccuracy (relies on correct calibration of pixel number to actual distance) - Transducer damage (loss of transmission by any of the crystals will lead to loss of image formation in that area. )

Answer 359

- Occurs when applied compensation does not match the actual attenuation - May be due to operator error or due to large difference between actual and assumed constant values - Results in bright or echo poor banding across the image - 2 useful TGC artefacts are post cystic enhancement and acoustic shadowing

Answer 360

Overall gain too low (areas mimic fluid created where echo information is lost) If too high cystic areas will appear solid.

Answer 361

Anatomical position of vessel Detail of vessel wall Lumen

Answer 362

Brightness Mode Real time 2D imaging Single frames are acquired and played sequentially

Answer 363

Map the course of the vessel Demonstrates vessel patency Identify stentotic segments Identify areas of flow turbulence

Answer 364

Hue or colour saturation are used to indicate mean Doppler frequency or variance Colour is used to indicate flow

Answer 365

- Extracranial carotid arteries - AAA screening and surveillance - Lower limb arterial or venous disease - Graft surveillance and perioperative vein mapping - Haemodialysis fistulas - Upper limb disease

Answer 366

Transient ischaemic attack (symptoms less than 24 hours) Loss of power or sensation of arms/legs/face Stroke (symptoms over 24 hours) US identifies the presence and extent of disease Ideal screening tool Treat: endarterctomy

Answer 367

High frequency - good resolution | 4-17MHz linear

Answer 368

- Palpable pulsatile abdominal mass - Surveillance of AAA - Screening for AAA - Suspicion of AAA (seen on radiograph) AAA= dilation over 3cm

Answer 369

3-6MHz Curvilinear | Need penetration

Answer 370

Just inferior to renal arteries or if suspect AAA, at the widest point. Measure inner wall to inner wall. AP - must be at 90 degrees to long axis (no salami slice)

Answer 371

Intermittent claudication Absent pulse Screening of symptomatic patients Diagnosis, location and grading of disease

Answer 372

4-17MHz linear | Use spectral Doppler

Answer 373

DVT | Varicose veins

Answer 374

Common Can result in fatal PE Painful swollen leg Chest pain

Answer 375

US now investigation of choice (not x-ray contrast venography) MRI useful for iliac veins where access is difficult (expensive) Need to assess the patency of deep veins, exclude the presence of a thrombus

Answer 376

4-17MHz linear

Answer 377

Synthetic | Native vein

Answer 378

Best long term patency Mapping prior to surgery Avoids removal of unsuitable veins Reduces wound necrosis

Answer 379

30% of native will develop significant stenosis Reduces the risk of graft failure Intermittent claudication

Answer 380

4-17MHz linear

Answer 381

AV connection that allows for high flow rates and can stand repeating needling for dialysis patients 4-17MHz linear

Answer 382

Stenosis False aneurysms from repeated needling Clot formation

Answer 383

- Acquire a set of 2D mages with positional information - Assemble the data into a 3D computer memory - Retrieve sleeted subset for display - Process and display selected data

Answer 384

1. Conventional 2D transducer motor driven in predetermined format 2. Conventional transducer hand held with positional sensors allowing maximum operator freedom 3. 2D matric array

Answer 385

Linear Sector format Anatomically constrained systems

Answer 386

Linear movement Creates multiple slices in a 3D box Useless for patient scanning Simple Bulky (too large and inflexible) Impractical

Answer 387

Motorised rocking sector Get a truncated pyramid with different slices Can rock with motor instead Reduces footprint Gives fan out Slice thickness is depth dependent

Answer 388

E.g. Intra vascular probe At each location it produces a slice at right angles to the probe Build an image from the inside out Successful in blood vessel As the region bend the machine is not aware and creates straight line

Answer 389

Have position sensors attached to probe Operator has considerable freedom May not acquire optimum sections for reconstruction Machine determines images using operator movement There may be some gaps and some double scanned

Answer 390

``` Operate using electromagnetic coupling Room conditions important Room needs to be fitted with detectors to work out where probe is Can't move machine out of the room Precision may be a problem ```

Answer 391

Can't move machine out of room Won't work if the couch is made of a conductive metal Location and precision can be problematic (need to know within 0.5mm in 3 axes and 2 angles) Operator may acquire suboptimal information

Answer 392

``` Allows for scanning in any plane Expensive and relatively uncommon Price will drop as increase manufacturers Can focus in 2 planes Can fire several at one time ```

Answer 393

250k/slice To cover 10cm need approx 100 slices (if slice thickness 1mm) 100x250 = 25Mb

Answer 394

Select an arbitrary section for display (most common) Use segmentation Use surface or volume rendering

Answer 395

Have 2 screens 1 clinical image and one showing where you are located Can see scans in different planes

Answer 396

Subdividing the image into component parts | Can be done manually or automatically

Answer 397

Using pseudo lighting to highlight a surface | May need perspective transformation

Answer 398

``` Not a true plane Visualisation of 3d structures as a 3d image Visualise surfaces (foetus) and internal structures (bones and vessels) ```

Answer 399

High speed acquisition involving multiple simultaneous line processing

Answer 400

``` Readily available Cost effective Reliable, repeatable, reproducible Noninvasive Safe Rapid Tends to be first line investigation ```

Answer 401

Liver Biliary system Urinary system Spleen

Answer 402

Prior to a and e - improve likelihood of poly traumatised patients POCUS - point of care us 2y e.g. Radiology department

Answer 403

``` Sonographer Radiologist Paramedics Emergency physician Trauma radiographer ```

Answer 404

3.5-6MHz curvilinear | Use 6+ in paediatrics or slim patients

Answer 405

``` TGC Overall gain Focus on ROI Consider MI and TI Compound imaging / harmonic imaging ```

Answer 406

More fine detail Increased lateral resolution More confident about diagnosis Time is a problem

Answer 407

Survey all upper abdomens and surrounding areas Use 3 planes Additional views with sub costal and intercostal views Measure where relevant Outline: liver, ligaments, gall bladder, kidneys, vessels, porta hepatic, cbd, pancreas, spleen Include colour and pulse Doppler to evaluate vessels

Answer 408

``` Size of organs and vessels Shape of organs and vessels Anatomical relationships Positions of organs and boundaries Texture ```

Answer 409

``` Ruq pain Epigastric pain Jaundice Abnormal LFTs Reflux ```

Answer 410

``` Homogeneous Midgrey echo texture Echogenic thin capsule surrounding Similar or slightly increase compared to kidney Ligaments are echogenic and linear ```

Answer 411

Diffuse disease e.g. Cirrhosis Masses Biliary dilation Portal hypertension

Answer 412

``` Confined to intra vascular space (mr and ct is extra cellular) Easy to administer Immediate effect Well tolerated Good patient safety record Provides additional information Cost effective ```

Answer 413

Characterises focal lesions Detects metastases Confirms normality Demonstrates vessel patency

Answer 414

Distended pear shaped sac Anechoic Echogenic thin wall Variable positions, size and shape

Answer 415

Gall stones Polyps Wall thickening

Answer 416

Echogenic Posterior acoustic shadowing Mobile Us very accurate at detecting

Answer 417

``` Common Not significant without gallstones Small intra luminal echogenic structure Fixed to wall No acoustic shadow Can be inflammatory, cholesterol or adenomyoma ```

Answer 418

Less than 3mm when fasting

Answer 419

``` Pancreatitis Dilation of pancreatic duct Pseudo cysts Masses Stones in pancreatic duct ```

Answer 420

``` Hypos choir Enlarged Pseudo cyst Pancreatic duct dilation Ascites ```

Answer 421

``` Echo free mass in lesser sac New has thin wall Old has thick Irregular borders Complex internal contents ```

Answer 422

Loin pain Recurrent UTI Haematuria Abnormal urine rest

Answer 423

``` Renal or bladder calculi Renal or bladder cancer Hydronephrosis Renal cysts Congential abnormalities ```

Answer 424

Luq pain Lymphoma Leukaemia Trauma

Answer 425

Cysts Metastasis Lacerations Splenomegaly

Answer 426

Identify CBD from portal vein and hepatic artery Observing hyperaemia e.g. Cholecystitis Differentiating benign and malignant Portal vein assessment - patency, direction, thrombus, occlusion Splenic varies

Answer 427

Focused assessment with sonography for trauma Rules in free fluid Yes or no Primary assessment of blunt abdo trauma Very quick can be performed during resuscitation

Answer 428

``` Good for soft tissue Real time Blood flow information Well tolerated Inexpensive Portable Non ionising Control of invasive procedure ```

Answer 429

Difficult in patients with high bmi due to poor penetration Unable to penetrate bone Can't image lungs Limited views if gas overlying Operator dependent Need to label as no way to orientate after

Answer 430

``` Transthoracic 4d Trans oesophageal Stress echo Contrast studies Dyssynchrony studies CRT optimisation Bubble studies ```

Answer 431

Assess cardiac structure and function Various views: parasternal (long axis and short axis), apical (2,4,5 chamber and long axis), sub costal, suprasternal and right sternal edge

Answer 432

Left lateral decubitus Raise left arm to open rib spaces Moves heart to front of chest Supine for sub costal and suprasternal views

Answer 433

Left sternal edge 4th ic space

Answer 434

Use m mode for left ventricle to get internal dimensions e.g. Ejection fraction Colour flow M mode for aorta and left atrium

Answer 435

Left sternal edge rotate 90 degrees from long axis Colour flow Doppler for peak velocity over valves Assess left ventricle, mitral valves and papillary muscles

Answer 436

``` Image from apex of heart Identify wall segments Colour flow through mitral valve Mitral pulsed Doppler Mitral cw Doppler Tricuspid colour flow Doppler Tricuspid cw Doppler ```

Answer 437

Identifying pericardial effusion | View IVC to see size and respiratory response

Answer 438

Aortic arch Good for aortic dissection Aortic Doppler Aortic cw Doppler

Answer 439

Phased array - need small footprint | 2-4MHz

Answer 440

Clinical examination Imaging Tissue sampling

Answer 441

Screening program - a symptomatic 3yr mammogram | Symptomatic breast clinics - symptoms or post surgical surveillance

Answer 442

Fibroadenoma (benign) Localised benign mass Abscesses in pregnancy

Answer 443

Cancer Increases with age Cysts

Answer 444

``` Mammography for over 40 Us for under 40 Standardised care Breast tissue over 40 is less glandular and less radio sensitive Mammogram is more sensitive than us ```

Answer 445

Lesion characterisation. Assessment of axila prior to sentinel node biopsy Intervention Evaluation of areas of asymmetry on mammo Exclusion of masses Implants Male patients Follow up measurements during chemo When mammo contraindicated (pregnancy) Evaluation of microcalcifications picked up on mammo

Answer 446

``` Highly operator dependent Time consuming Small subtle changes can be missed Needs skilled use of equipment Microcalcifications hard to see ```

Answer 447

7-15MHz linear array Dynamic range 60dB Can do compound imaging, harmonic imaging, extended Fov, Doppler or elastography

Answer 448

Chaotic irregular branching pattern Hypervascular Large vessels for lesion size

Answer 449

Organised vasculature Peripheral Aligned with septa Low number of vessels

Answer 450

Supine with ipsilateral arm above head Better visualisation of lower quadrants Flatten breast to chest wall Minimise movement of breast

Answer 451

Longitudinal Radial Transverse Anti radial

Answer 452

Ductal proliferation Hyperplasia of glandular epithelium Increase stromal tissue

Answer 453

``` Transition of echogenicity from mass and surrounding tissue Signifies change in acoustic appearance Well circumscribed Lobular end I'll defined Irregular Hyperechoic ```

Answer 454

Comparison of echogenicity of surrounding tissues Hypo/hyper/an. - echoic Homo/Herero. - geneous

Answer 455

``` Round Well defined An or Hyperechoic Homogeneous Posterior acoustic enhancement Compressible Mobile Wider than deep Surroundings unaltered ```

Answer 456

``` Irregular Ill defined Hypoechoic Heterogeneous Posterior acoustic shadowing Rigid Fixed or mobile Deeper than wide Altered surroundings ```

Answer 457

``` 1 normal 2 benign 3 indeterminate - probably benign 4 suspicious of malignancy 5 highly suspicious of malignancy ``` Follow up 345

Answer 458

Cyst aspiration | Hook wire placement

Ultrasound Flashcards

(503 cards)