This document provides an overview of techniques for optimizing echo images. It discusses adjusting various ultrasound machine parameters like transducer type, echo modes, sector size, depth, frequency, dynamic range, gain, and focus to obtain high quality images. The objectives are to learn the manufacturer's techniques for achieving the best possible contrast in echo images by manipulating these different parameters.

1. KNOBOLOGY
Dr Hafeesh Fazulu
PUSHPAGIRI CARDIOLOGY
Pushpagiri Institute of Medical Sciences
Thiruvalla, Kerala.
+91 9995706688
1st July 2021
Optimising ECHO Images

2. Knobology

4. Objectives of the lecture
• Learn the manufacture’s techniques to optimize the BEST POSSIBLE
CONTRAST for echo image

5. References

6. What to Cover?
• Echo Modes
• Transducer
• Types of Arrays
• Probe movements
• 2D-ECHO
• Grayscale Maps
• Frequency
• Dynamic Range
• Sector Size
• Sector Depth
• Focus
• Gain
• Time Gain Compensation (TGC)
• Zoom
• Frame Rate
• Compression
• B mode Colorisation
• Harmonic Imaging

7. What to Cover?
• DOPPLER
• Velocity Scale
• Baseline
• Sweep Speed
• Sample size
• Doppler angle
• Wall filters
• Pulse repetition frequency (PRF)
• Doppler Gain
• COLOR DOPPLER
• Sector Size
• ROI
• Color Gain
• Color Maps
• Color Aliasing
• Color Baseline
• M MODE
• Sweep speed
• Color M Mode

8. Manufacturers

9. Our Echo Machine

11. 2D

12. Color

13. Color
M mode

14. PW & CW

15. Probe Mechanical Index
Thermal Index
Current
Date&Time
Parameter Window
Soft Menu Window
Cine Progress bar
Current Menu Name
Depth
Focus

20. General Rule

21. “Search in cirles”

22. Females
• How to tackle the breast tissue interference?

23. ECHO
LANGUAGE

24. HYPERECHOIC HYPOECHOIC ANECHOIC
More echogenic than
surrounding tissue
Less echogenic than
surrounding tissue
Devoid of echoes
BLACK

25. MODES in ECHO

26. • A Mode – Amplitude of reflected energy at certain depth
• B Mode – Brightness – energy as the brightness of the point
• M Mode – Motion – seen as a curve
• 2D Mode -
• 3D Mode -
• 4D Mode -

28. A Mode

29. TRANSDUCER
Cardiac transducer

30. Transducer
• Current is passed through Piezoelectric Crystal which vibrates and
generates ultrasound waves
• It will generate a electrical impulse when it is deformed by reflected
sound energy
• Lower the Frequency – more penetration

31. Curved Probe

32. Types of Arrays
• LINEAR
• Linear Sequential array (min 4 cm width)
• Fired sequentially
• Linear Phased array
• Fired simultaneously in phases (can steer and focus)
• CURVED
• Curved sequential array (Convex array)
• Curved Phased array (Concave array)
• AANULAR Array
IVUS ???
Mechanical rotation & Phased array
https://www.youtube.com/watch?v=AG2lTLh1eUo&ab_channel=Examrefresh

34. P21 – Phased
L38 – Linear
C60 - Curved
4cm

36. What is Phased array transducer?
• Series of small piezoelectric elements are interconnected
electronically
• Can steer and focus – by manipulating the timing of excitation of
individual elements

38. `

41. Cardiac Probe
• Phased array probe
• Smaller footprint – to examine between RIBS
• Best for structures deeper than 6cm, upto 35cm
• Low definition, High Penetration
• 3 MHz – 5 MHz
• In Short 3s – 5s

42. Why we apply jelly?
• Air is a poor transmitter of sound
• So jelly is applied to create a
medium.
• Does the ECG jelly vs ECHO jelly
differ ?
• Sound vs Electricity

43. Pediatric patients
• Thin chest wall, less depth
• Ideal probe is with HIGH FREQUENCY with a depth of 4-5cm
• If no probe, Use the HIGHEST POSSIBLE FREQUENCY for the available
probe
• Typical frequency in Pediatric Probe is 9s (9 MHz)

44. Holding the probe
• Under the probe – like a pencil
• Over the probe – subcostal view
Hand under / over

45. Probe movements

48. • Sliding – Translate
• Rotation
• Tilting - Fanning, Sweeping, Angulating
• Rocking – heel Toeing
• Compressing - Stabbing

50. Near field and Far Field
• Image is optimal within the near field
• Getting a maximum length of near field is better.
• Length of Near field depends on radius of transducer and wavelength
of ultrasound.
• Optimal Ultrasound – larger radius, higher frequency

52. ULTRASOUND-TISSUE INTERACTION
1. Reflection
2. Scattering
3. Refraction
4. Attenuation

53. 1. Reflection
• Compare to light reflection from a mirror
• Depends on
• 1. Difference in acoustic impedence
• 2. ANGLE of reflection
• Optimal return of reflected ultrasound occurs at a perpendicular angle ie 90 degrees

54. 2. Scattering
• RBC’s cause scattering cause the radius of RBC’s is smaller than the
wave length of ultrasound signal
• DOPPLER works on the principle of Scattering
• Extent of scattering depends on :
• 1. Particle size
• 2. Number of particles
• 3. Transducer frequency
• 4. Compressibility of blood cells and plasma (Hematocrit)

55. • Scattering within TISUES (Myocardium)
• Causes SPECKLES
• Tracking these speckles – can track the motion of myocardium

56. 3. Refraction
• No reflection, but refracts into the tissue at a different angle
• E.g. as in a Curved Lens
• Importance – refracted waves can reflect later causing DOUBLE
IMAGE artefacts

57. 4. Atteneuation
• Depends on
• 1. Attenuation coefficient of the tissue
• 2. Transducer frequency
• 3. Distance from transducer
• 4. Ultrasound intensity (Power)

58. RESOLUTION

59. What is Resolution?
• Ability to distinguish two different points clearly

60. • Spatial
• Axial (Z)
• Lateral (X & Y)
• Temporal – Moving structures
• Described as Frame Rate
Temporal – means relating to time https://www.youtube.com/watch?v=kCjHXh3lzcg&ab_channel=UnitechDUS

62. • AXIAL RESOLUTION – ability to display two structures when they are
PARALLEL to the sound beam

63. • LATERAL RESOLUTION

65. 2D ECHO

66. Proc – DDP Number

67. Grayscale Maps

68. • Determines how shades of gray will best be displayed to highlight
specific findings in the image.
• Map F
• Map A

71. FREQUENCY
3-5 MHz

72. • Higher frequency – Less Penetration – Better Image contrast
• Lower frequency – More Penetration – Reduced Image Contrast

75. `
3 MHz 5 MHz
Better resolution

76. DYNAMIC RANGE
dB

77. • Adjusts the appearance of the SHADES OF GREY on image
• Low Dynamic Range - Black and White (few shades of grey)
• High Dyanamic range - more shades of grey, more of tissue types
• Optimal 70-75dB

78. Dynamic Range 50 Dynamic Range 75
More BLACK AND WHITE
Less grey shades
More shades of Grey
Useful when looking for LV thrombus, LV noncompaction etc

81. POWER
In dB
as per FDA approval

83. When power is reduced, it reduces the signal-to-noise ratio, so that the
image may become noisier.

84. Mechanical Index (MI)
“extent of mechanical damage to tissue”

86. • The mechanical index (MI) is an attempt to measure part of an
ultrasound beam's bioeffects.
• It is inversely proportional to the frequency of the beam.
• Therefore, higher frequencies have a lower mechanical index.
• Mechanical index is an indication of an ultrasound beam's ability to
cause cavitation-related bioeffects, and this is currently thought a
reasonable proxy for micromechanical damage. It is "strictly a
cavitation index," but is meant to be interpreted more broadly as
tissue mechanical stress/damage.

87. • FDA mandates that the mechanical index be kept below 1.9.
• Unitless numbers
• Mechanical index = peak negative pressure / √(center frequency of the US beam)

88. Importance in Contrast Echo
• Interestingly, a consequence of the relationship between frequency
and cavitation is that different bubble sizes are susceptible to
cavitation at different frequencies. Two different ultrasound
frequencies (e.g. 4 MHz and 9 MHz) cavitate bubbles of different
sizes. This is important in contrast-enhanced ultrasound, where
cavitation of the bubbles is desired.

90. Thermal Index

91. • The thermal index (TI) is intended as a measure of an ultrasound
beam's thermal bioeffects.
• It is often displayed on ultrasound screens (along with the mechanical
index).
• The thermal index depends on:
• a measure of time-averaged acoustic power
• assumptions of the properties of the tissue being heated
• assumptions about the path of the ultrasound beam

92. • The clinical relevance of the thermal index most often comes into play
with imaging of the embryo.
• Color and spectral Doppler imaging calls for increased levels of
ultrasound output power, and this in turn increases the thermal
index.
• The thermal index may be displayed in some ultrasound systems as:
• TIS: thermal index in soft tissue
• TIB: thermal index for bone at the focus
• TIC: thermal index for cranial bone

94. SECTOR SIZE

95. • Wider sector size decreases Frame rate and decreases temporal
resolution
• If fast moving structure, decrease sector size. Eg Valve

96. Depth 170mm
Frame Rate 83 Hz
Depth 240mm
Frame Rate 73 Hz
Depth 240mm
Frame Rate 43 Hz

97. Depth 170mm
Frame Rate 83 Hz
Depth 240mm
Frame Rate 73 Hz
Depth 240mm
Frame Rate 43 Hz

98. SECTOR DEPTH

99. Not needed
Reduce depth and increase frequency

102. FOCUS
Transducer Beam Focus

103. • Resolution is increased at that particular point
• Eg Aortic Valve in stenosis

106. How does it do?

107. GAIN
Overall GAIN

108. • Overall brightness of the image
• AUTO GAIN

111. Time Gain Compensation
(TGC)

112. • Optimum is
• Decrease in the near field
• Increase in the far field
Near Field
Far Field

116. Why is it called so?
• ‘Time Gain Compensation’ is so called because it compensates
for the attenuation of ultrasound energy with depth.
• Depth is synonymous with time in ultrasound, because the
ultrasound machine calculates the depth of structures based on
how long it takes for ultrasound to reflect off them and return to
the transducer.
• The ultrasound machine amplifies signals received from deeper
than those it receives from superficial ones
“Depth Gain Compensation”

117. ZOOM

118. • Magnification without change in resolution
• Use Zoom liberally.

120. FRAME RATE

121. • Image produced per unit time
• Higher Frame rate – Higher TEMPORAL Resolution
• Temporal resolution is the ability to distinguish TWO MOVING points

122. COMPRESSION

124. • Ultrasound wave is often graphically depicted as a sine wave in which
the peaks and troughs represent the areas of compression and
rarefaction
• Controls the amount of contrast
• MORE Compression  MORE Contrast

125. REJECTION

126. • When increased, Low level echoes are eliminated and appear DARKER

127. CONTOUR

129. B Mode COLORISATION

132. HARMONIC IMAGING
“tissue also generates sound waves”

134. • When Fundamental Frequency is passed
through tissue, the TISSUE generates a
frequency which can be detected by transducer
– HARMONIC FREQUENCY
• New frequency generated is integral multiples
of the fundamental frequency
• Used in Contrast Echo
• At the site of entry of Fundamental frequency
into Tissue, HIGH FREQUENCY is generated
• Close to Chest wall – little harmonic signal
• 4-8 cm within Chest wall – maximum harmonic
signal

135. Eliminating the Fundamental Frequency
1. FILTERS
2. PULSE INVERSION

138. Class 2/2

139. DOPPLER
X6
PW & CW
Color Doppler
Power Doppler
Tissue Doppler
Duplex Scanning (Trad US + Doppler)

140. PW & CW

141. History
• Christian Doppler in 1842
• DOPPLER EFFECT
• observed frequency of a wave depends
on the relative speed of the source and
the observer

142. Doppler Effect

143. • Change in frequency is called the Doppler Shift
• Upward shift
• Downward shift
• Primary Job of Doppler is to measure the doppler shift and from this
VELOCITY can be calculated

144. Factors affecting Doppler
• Angle
• Keep it as parallel as possible
• Upto 20 degree is acceptable
• Frequency
• Lower the Frequency

145. • Pulse Wave – how velocity changes at a particular REGION
• Sample Volume
• Speed Limitation – 1.7m/s
• Continuous Wave – how velocity changes along a LINE
• 2 Crystals
• Both gives a SPECTRAL DISPLAY
Two Crystals
PULSE vs CONTINOUS
PW is like aiming and Shooting
In return u get velocity
One Crystal

146. • X axis – Time
• Y axis – Frequency Shifts
• Frequency shifts towards transducer – ABOVE
• Frequency shifts away transducer – BELOW
• Amplitude – by shades of grey
• Velocity – position on X axis
• Sample Volume
• PRF/Velocity Scale
• Spectral Window
• Spectral window denotes LAMINAR FLOW

148. Spectral Display
And its Components

149. SPECTRAL Display
• Doppler frequency shifts displayed as a spectrum
• Graphic display of VELOCITY over TIME
PSV – peak Systolic Velocity EDV – peak Systolic Velocity

150. Laminar vs Turbulent Flow
• Spectral Window
• Region of no doppler signal
• Indicates LAMINAR Flow
• Spectral Broadening
• Indicates TURBULENT Flow
• May occur due to incorrect angle also
• False high velocities

151. Laminar or Turbulant ? By Spectral Doppler
“Snow eats
mountain”

152. PSV – peak Systolic Velocity

154. Flow patterns

155. PRF
(Pulse RepetitionFrequency)
LPRF
HPRF
(in Pulsed Doppler)
Scale = PRF

156. • Number of pulses transmitted from transducer PER SECOND is PRF
• PRF = 2 x f DOP
• To accurately represent a given frequency, it must be SAMPLED AT
LEAST TWICE THE FREQUENCY
• Eg : a sound wave travelling at 2 waves/second should be sample at 4 times per second.
• “Frequency shift is too fast for rate of sampling” - Aliasing
• NyQUIST Limit
• Upper limit of frequency that can be detected by a pulsed system
• = ½ PRF
DOP - Doppler

157. Eg : a sound wave travelling at 2 waves/second should be sample at 4 times per second.
Dotted Lines – represent sampling
Sampling
twice in first
wave

158. • Frequency shift is too fast for rate of sampling

159. VELOCITY SCALE
And Aliasing

161. Adjusting PRF

162. BASELINE

164. SWEEP SPEED

165. • Similar to ECG speed (eg 25mm/sec)
• Default – 100mm/sec
• Adjust based on the heart Rate
• Higher Sweep speed – Less complexes

167. SAMPLE VOLUME SIZE
SAMPLE GATE

168. Line of insonation
Sample Volume

169. • Larger the sample gate  more velocities are
included  affects resolution of doppler
waveform
• Typically 2-4 mm
• >4mm may cause noise

172. DOPPLER ANGLE
And ANGLE CORRECTION

173. • Cardiac – assumed to be 0 degrees
• Keep it parallel to blood flow
• No correction needed
• Upto 20 degree is acceptable
• Vascular –
• Correction needed for vascular
• The closer the corrected angle is to 0,
the more accurate the velocity
results
• Optimal <60 degrees
• > 60 degrees – less accurate velocity
better

174. WALL FILTERS
HIGH PASS FILTERS
(allowing only higher frequencies to pass the filter)

175. • Due to a large dynamic range of the
returning doppler signals there is a need
to reduce the amplitude of “CLUTTER”
signals (formed from myocardium and
valve movement) which reduces the
required dynamic range
• Wall filters are FILTERS designed to reduce
signals based on their FREQUENCY SHIFT
• Filters signals with lower Frequency shifts

177. DOPPLER GAIN
Overall
Vs
2D Gain
Doppler Gain
Color Gain

178. • Post processing amplication of return echoes
• Too much gain will cause over estimation of doppler signal and may
cause a degree of spectral broadening
• Optimal setting – is that which gives a SMOOTH VELOCITY CURVE

179. Smooth Curve

180. COLOR DOPPLER
“a form of pulse waved doppler”

181. 2D superimposed by Color Doppler – Separate settings for each

182. 2D Sector Size

183. • Should be kept small as possible
• Since it will give HIGH FRAME RATES in Color Doppler

184. 2D Sector Size
ROI / Color box Size

186. ROI / Color Box Size

187. 2D Sector Size
ROI / Color box Size

188. OVERALL GAIN
2D Gain
During COLOR DOPPLER

189. • B Mode should be kept at a LOW GAIN, so that the image is dark
• Since the software tends to allocate color to darker areas

191. COLOR GAIN
Active Gain

195. COLOR MAPS

198. Color Aliasing
&
VELOCITY SCALE / PRF
For COLOR DOPPLER

199. 2 ways to remove color aliasing
1. Change velocity scale
2. Change Baseline

200. • Velocity Scale = PRF

203. Effect of Scale on Regurgitation

204. Color Aliasing
&
COLOR Baseline
For COLOR DOPPLER

207. BURST LENGTH

208. • Burst of high intensity
ultrasound signals
• Given during Contrast
echocardiography

209. VARIANCE
“Frequency Spreads”
To detect Flow disturbances

214. Doppler Tissue Imaging (DTI)
TDI – Tissue Doppler Imaging
TVI – Tissue Velocity Imaging
TVE – Tissue Velocity Echocardiography

215. • Tissue is the target unlike for RBC
• Tissue has a greater REFLECTIVITY and SLOW Motion
• Filters are set to exclude high Velocities

216. Tissue Doppler Modes
• Pulse Wave Doppler
• Color 2D
• Color M Mode

217. Waveforms in TDI
• Sa (S’) – Peak Systolic Annular Velocity
• Ea (E’) – Early rapid filling ANNULAR Velocity
• Aa (A’) - Atrial Systole ANNULAR Velocity

218. S1

220. COLOR
POWER DOPPLER (CPD)
CPD – Color Power Doppler

221. • Single Color
• More sensitive to Detect Flow
• Useful in LOW FLOW situations
• Eg capillaries in testicular torsion
• Helpful in myocardial ischemia?
• Does not detect DIRECTION

222. M Mode

223. • Ultrasound is transmitted and received along ONE SCAN LINE
• Cursor should be aligned perpendicular the line of interest
• Very HIGH TEMPORAL RESOLUTION

224. M MODE
SWEEP SPEED

225. Changes number of cardiac cycles that can be shown on the horizontal axis of the
M-mode display.

226. Color M Mode

227. Color M mode assists with the timing of events.
Image 1 demonstrates M mode with MS.
In image 2, color M mode demonstrates the inflow with MS in diastole and turbulent flow from MR in systole.

228. STEER

229. How to steer ?

230. DDP
Data Dependent Processing
Proc.

231. • Removes NOISE
• Performs temporal processing which
reduces random noise without affecting
the motion of significant tissue structures.
• An index number is displayed in the status
window (under Proc) to indicate the
relative DDP level.

232. REVERBERATION
Diff On/Off

234. • Affects the level of reverberations in the image.
• When turned On, the frame rate (or the number of focal zones) will
decrease, & Focal zones reduced , while the reverberations will be
attenuated.

235. 4D ECHO

237. REVISION

238. Our Echo Machine

240. 2D

241. Color

242. Color
M mode

243. PW & CW

244. Probe Mechanical Index
Thermal Index
Current
Date&Time
Parameter Window
Soft Menu Window
Cine Progress bar
Current Menu Name
Depth
Focus

250. CONNECTIVITY

251. • DICOM - Digital Imaging and Communications in Medicine
• Dicom Server
• Dataflow
• MPEGVue

253. Standalone scanner

254. EchoPAC PC – Direct connection

255. EchoPAC PC – Indirect
MOD – Magnetic Optical Disk

256. DICOM Server
• How Tele-reporting by Radiologists work….

257. PACS Systems (picture archiving and communication system)

258. THANK YOU

259. Pulse INVERSION
• Pulse inversion transmits pulses of ALTERNATING POLARITY
• Multiple positive phase and negative phase pulses are sent
• Returning signals combined to enchance contrast signals, while
eliminating tissue

262. Pulse Inversion

263. DOPPLER SCALE

264. • Representation of PRF