1. Monitoring Electric-Field Induced Changes in
Biological Tissues and Phantoms By Using
Ultrasound
Jagdish Bhatt
M.Sc. Candidate
Supervisor: Dr. Yuan Xu
January 8, 2015

2. Outline
• Principles of Ultrasound Imaging
• Motivation
• Experimental Methods
• Results
• Conclusions
2
• Future Work

3. Principles of Ultrasound Imaging
Figure : Basic principles of Ultrasound imaging
J. G. Fox, S. W. Barthold, M. T. Davisson, and A. L. Smith, The Mouse in Biomedical Research Normative Biology, Husbandry, and Model, Second
Edition. Burlington: American College of laboratory Animal Medicine series, 2007
• Reflection of sound energy by
interfaces and scatters
• Ultrasound waves are reflected
from the interfaces when there is
change in density or bulk modulus of
the material
• Echo waves are received by the
transducer to form a A-line.
• Scan the transducer to obtain B
mode images.
3

4. Motivation
• To use ultrasound to image the electric/electro-
kinetic properties of biological tissues
• The electric/electro-kinetic properties of tissues
are correlated to the physiological and
pathological status of tissues
4

5. Electro-kinetic Phenomena (EKP)
Motion of particles and fluids under the influence of an
electric field:
• Electrophoresis
The movement of electrically charged particles (solid, liquid or
gaseous) in an electric field, which is filled with a liquid as second phase.
• Electro-osmosis
The movement of a liquid along a solid or a liquid surface driven by an
electric field
5

6. Electrophoresis
𝑣𝑒= −
𝜖0 𝜖 𝑟 𝐸𝜁
𝜂
Where, 𝐸 is the electric field strength
𝜁 is the zeta potential
𝜖0 is the permittivity of the
vacuum , 𝜖 𝑟is the relative permittivity of
the liquid, 𝜂 is the coefficient of viscosity of
the medium and 𝑣𝑒 is the electrophoretic
velocity of the particles.
Figure : Principle of the particle electrophoresis
6
Fel = -EQ
Ffr = 6 π η r ve
F. Simon, “Electro-kinetic Phenomena,” Leibniz Institute of Polymer Research, Dresden, Germany, 2009.

7. Electro-osmosis
7
Figure: The principle of electro-osmosis.
• A. V. Delgado, F. González-Caballero, R. J. Hunter, L. K. Koopal, and J. Lyklema, “Measurement and interpretation of electrokinetic phenomena,” J. Colloid
Interface Sci, vol. 309, no. 2, pp. 194–224, May 2007.
• Electro-osmosis, Thomson-Brooks/Cole, 2004
𝑣𝑒 𝑜
=
𝜖 𝑟 𝑠 𝜖0 𝜁
𝜂
𝐸
Where, 𝜖 𝑟 𝑠 is the relative
permittivity of the
electrolytic solution, 𝐸 is the
electric field strength
𝜁 is the zeta potential, 𝜂 is
the coefficient of viscosity of
the medium and 𝜖0 is the
permittivity of the vacuum.
The electro osmotic velocity is given
by the Smoluchowski equation:

8. Experimental Methods
Figure 1: Schematic diagram of
transducer and sample
Figure2: Experimental setup
O. Doganay and Y. Xu, “The effect of electric current in biological tissues on ultrasound echoes,” 2009 IEEE Int. Ultrason. Symp., pp. 2103–2106, Sep. 2009.
O. Doganay and Y. Xu, “Electric-field induced strain in biological tissues.,” J. Acoust. Soc. Am., vol. 128, no. 5, pp. EL261–7, Nov. 2010. 8

9. 9
Hypothesis and objectives
Hypothesis:
• Electric field can induce mechanical changes on biological tissues and ultrasound phantoms
depending on the amplitude, frequency and duration of the applied electric field.
• Amplitude of the ultrasound echoes from the tissues can be monitored to reveal the current
distribution in the sample.
Objectives:
• Study the electric/electro-kinetic effects in layered tissues (muscle-fat) and phantoms.
• Study the electric field induced mechanical changes (EIMC) based on the changes in
amplitude of RF signals, mean of the signal spectrum at the modulation frequency, RMS of
the noise in the spectrum and SNR during the application of electric field in tissues and
phantoms.

10. Amplitude change due to electric current
Figure: The echo signals from a piece of bovine muscle tissue before electric
current and after electric current application were compared.
O. Doganay and Y. Xu.The effect of electric current in biological tissue on ultrasound echoes, 2010.

11. 11
Experiment phantoms
(a) (b)
(c) (d)
Figure: (a) Porcine heart muscle and the gelatin sample. (b) Porcine heart sample fixed with electrodes and placed on
the top of the gelatin sample. (c) Porcine heart muscle, fat and the gelatin sample. (d) Porcine heart sample fixed with
electrodes and placed on the top of the fat.

12. 12
Data Analysis
1. Amplitude change in various windows with slow time
0 100 200 300 400 500 600 700 800
-1
-0.5
0
0.5
1
1.5
x 10
-3
Slow time(s)
Amplitude(V)
Figure: The amplitude change of a porcine heart muscle window. The current
applied from 191s to 572s (1.33V/cm and 0.02Hz) for 381s.

13. 13
2.Frequency spectrum of the signal during electric
field application
200 250 300 350 400 450 500 550
-1
-0.5
0
0.5
1
1.5
x 10
-3
slow time(s)
Amplitude(V)
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
5
6
x 10
-4
Frequency (Hz)
Amp,FFT
(a) (b)
Figure: (a) A part of a signal of a porcine heart muscle window during electric field application. (b)
Frequency spectrum of the signal.

14. 14
3. Mean signal and root mean square value of the
noise
(i) Amean =
𝐴 𝑖
5
𝑖=−5
11
Where, Ai is the amplitude corresponding
to ith frequency in the spectrum and i is
an integer.
Where N is the total number of points
(frequencies) between 0.05Hz and
0.25Hz, A is the amplitude of each small
peaks corresponding to nth frequencies in
the spectrum
(ii) Arms =
1
𝑁
𝐴 𝑛 2
Figure: Schematic representation of the signal and noise in the
spectrum
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
5
6
x 10
-4
Frequency (Hz)
Amp,FFT
Signal
Noise

15. 15
4. signal-to-noise ratio (SNR)
Signal-to-noise ratio (SNR) =
𝑴𝒆𝒂𝒏 𝒔𝒊𝒈𝒏𝒂𝒍
𝑹𝑴𝑺 𝒏𝒐𝒊𝒔𝒆
Figure: Schematic representation of the signal and noise in the spectrum
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
5
6
x 10
-4
Frequency (Hz)
Amp,FFT
Signal
Noise

16. Samples for experiments
1. Gelatin layer electrically isolated from tissue layer
• Longer time experiment using porcine heart muscle and gelatin sample
separated by thin plastic
• Shorter time experiment using porcine heart muscle and gelatin sample
separated by thin plastic
2.Gelatin layer in contact with tissue layer
• Longer time experiment using layered tissues and phantoms (porcine
heart muscle, fat and gelatin) without using plastic between samples
• Longer time experiment using porcine heart muscle and gelatin sample
without using plastic between samples
3. Uniform gelatin phantom
16

17. 17
(A) Ultrasound RF signal, mean of the signal, RMS noise and signal-to-noise ratio
0 20 40 60 80
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Fast time (µs)
EchoAmplitude(mV)
a
Figure: (a) Ultrasound RF signal versus fast time (20.29 µs/30.20 µs/37.73 µs corresponds to the front, mid and rear
boundaries). (b) Mean of the signal. (c) Root mean square (RMS) of the noise. (d) Signal-to-noise ratio (SNR) with
fast time.
20 25 30 35 40
0
2
4
6
8
10
Fast time (µs)
SNR
d
20 25 30 35 40
0
1
2
3
4
5
6
x 10
-4
Fast time (µs)
Amplitude(V)
c
RMS noise
20 25 30 35 40
0
0.2
0.4
0.6
0.8
1
1.2
x 10
-3
Fast time (µs)
Amplitude(V)
b
Mean signal
1. Results of gelatin layer electrically isolated from tissue layer
(i) Longer time experiment using porcine heart muscle and gelatin sample
Muscle
Gel

18. 18
(B) Amplitude versus slow time and their spectrums during
electric field
Figure: (a), (c) and (e) are amplitude changes of porcine heart windows 42, 50 and 51. (b), (d) and (f) are frequency spectrums
during electric current of pork heart windows 42, 50 and 51 respectively.
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
slow time(s)
Amplitude(V)
a
Pork muscle 42
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
c
Pork 50
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
e
pork 51
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-4
Frequency (Hz)
Amp,FFT
b
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-4
Frequency (Hz)
Amp,FFT
d
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-4
Frequency (Hz)
Amp,FFT
f
Start of current — 209s
End of current — 1223s

19. 19
Amplitude versus slow time and their spectrums during electric field
Continued..
Figure: (g), (i) and (h), (j) are amplitude changes and frequency spectrums of gelatin windows 112 and
115 respectively.
0 500 1000 1500
-6
-4
-2
0
2
4
6
x 10
-4
Slow time(s)
Amplitude(V)
g
Gel 112
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-5
Frequency (Hz)
Amp,FFT
h
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
i
Gel 115
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
5
6
x 10
-5
Frequency (Hz)
Amp,FFT
j

20. 20
(A) Ultrasound RF signal, mean of the signal, RMS noise and signal-to-noise ratio
0 20 40 60 80
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Fast time (µs)
EchoAmplitude(mV)
a
Figure: (a) Ultrasound RF signal versus fast time (17.37 µs/27.24 µs/32.9 µs corresponds to the front, mid and rear
boundaries). (b) Mean of the signal. (c) Root mean square (RMS) of the noise. (d) Signal-to-noise ratio (SNR) with all
the windows
18 20 22 24 26 28 30 32 34
0.5
1
1.5
2
2.5
3
3.5
x 10
-4
Fast time (µs)
Amplitude(V)
b
Mean signal
18 20 22 24 26 28 30 32 34
0.5
1
1.5
2
2.5
3
3.5
4
x 10
-4
Fast time (µs)
Amplitude(V)
c
RMS noise
18 20 22 24 26 28 30 32 34
0
1
2
3
4
5
6
Fast time (µs)
SNR
d
(ii) Shorter time experiment using porcine heart muscle and gelatin
sample

21. 21
(B). Amplitude versus slow time and their spectrums during electric
field
Figure: (a), (c) and (e) are amplitude changes of porcine heart windows 46, 47 and 50. (b), (d) and (f) are frequency spectrums during
electric current of porcine heart windows 46, 47 and 50 respectively.
0 100 200 300 400 500 600 700 800
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
a
Pork 46
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-4
Frequency (Hz)
Amp,FFT
b
0 200 400 600 800
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
c
Pork 47
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-4
Frequency (Hz)
Amp,FFT
d
0 100 200 300 400 500 600 700 800
-1
-0.5
0
0.5
1
1.5
x 10
-3
Slow time(s)
Amplitude(V)
e
Pork 50
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
5
6
x 10
-4
Frequency (Hz)
Amp,FFT
f
Start of current — 191s
End of current — 572s

22. 22
Amplitude versus slow time and their frequency spectrums during electric field
Continued..
Figure: (g) and (h) are the comparison of amplitude change of porcine heart muscle window 47 and 50 and their frequency spectrums
during electric current. (i), (k) and (j), (l) are amplitude changes of gelatin window 97 and 102 and their frequency spectrums respectively.
0 200 400 600 800
-1
-0.5
0
0.5
1
1.5
x 10
-3
g
Pork 47
Pork 50
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
5
6
x 10
-4
Frequency (Hz)
Amp,FFT
h
Pork 47
Pork 50
0 200 400 600 800
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
i
Gel 97
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
2
4
6
8
x 10
-5
Frequency (Hz)
Amp,FFT
j
0 200 400 600 800
-6
-4
-2
0
2
4
6
x 10
-4
Slow time(s)
Amplitude(V)
K
Gel 102
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-5
Frequency (Hz)
Amp,FFT L

23. 23
(A) Ultrasound RF signal, mean of the signal, RMS noise and signal-to-noise ratio
0 20 40 60 80
-1
-0.5
0
0.5
1
Fast time (µs)
EchoAmplitude(mV)
a
Figure: (a) Ultrasound RF signal versus fast time (18.51 µs/27.29µs/31.38 µs/37.31µs corresponds to the front,
muscle-fat, fat-gelatin and rear boundaries) (b) Mean of the signal. (c) Root mean square (RMS) of the noise. (d)
Signal-to-noise ratio (SNR) with all the windows.
18 20 22 24 26 28 30 32 34 36 38
0
0.5
1
1.5
2
x 10
-3
Fast time (µs)
Amplitude(V)
b
Mean signal
18 20 22 24 26 28 30 32 34 36 38
0
1
x 10
-4
Fast time (µs)
Amplitude(V)
c
RMS noise
18 20 22 24 26 28 30 32 34 36 38
0
5
10
15
20
25
30
Fast time (µs)
SNR
d
2. Results of gelatin layer in contact with tissue layer
(i) Longer time experiment using porcine heart muscle, fat and gelatin
Muscle
Fat
Gel

24. 24
(B). Amplitude versus slow time and their spectrums during electric
field
Figure: (a), (c) and (b), (d) are the amplitude change signal of the porcine heart muscle window 35 and 36 and their frequency
spectrums respectively. (e) and (f) are amplitude change signal of fat window 106 and it’s frequency spectrum.
0 200 400 600 800 1000 1200 1400 1600
-1.5
-1
-0.5
0
0.5
1
x 10
-3
slow time(s)
Amplitude(V)
a
Pork 35
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0
2
4
6
x 10
-4
Frequency (Hz)
Amp,FFT
b
0 200 400 600 800 1000 1200 1400 1600
-2
-1
0
1
x 10
-3
slow time(s)
Amplitude(V)
c
Pork 36
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0
2
4
6
x 10
-4
Frequency (Hz)
Amp,FFT
d
0 200 400 600 800 1000 1200 1400 1600
-1
-0.5
0
0.5
1
x 10
-3
slow time(s)
Amplitude(V)
e
Fat 106
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0
2
4
6
8
x 10
-5
Frequency (Hz)
Amp,FFT
f
Start of current — 217s
End of current — 1382s

25. 25
Amplitude versus slow time and their spectrums during electric field
Continued..
Figure: (g) and (h) are the amplitude change signal of the fat window 108 and it’s frequency spectrum. (i), (k) and (j),
(l) are the amplitude change signal of gelatin window 127 and 133 and their frequency spectrums respectively.
0 200 400 600 800 1000 1200 1400 1600
-1
-0.5
0
0.5
1
x 10
-3
slow time(s)
Amplitude(V)
g
Fat 108
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0
2
4
6
8
x 10
-5
Frequency (Hz)
Amp,FFT
h
0 200 400 600 800 1000 1200 1400 1600
-1
-0.5
0
0.5
1
x 10
-3
slow time(s)
Amplitude(V)
i
Gel 127
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0
0.2
0.4
0.6
0.8
1
x 10
-4
Frequency (Hz)
Amp,FFT
j
0 200 400 600 800 1000 1200 1400 1600
-5
0
5
x 10
-4
slow time(s)
Amplitude(V)
k
Gel 133
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0
2
4
6
x 10
-5
Frequency (Hz)
Amp,FFT
l

26. 26
(A) Ultrasound RF signal, mean of the signal, RMS noise and signal-to-noise ratio
0 20 40 60 80
-1
-0.5
0
0.5
1
Fast time (µs)
EchoAmplitude(mV)
a
Figure: (a) Ultrasound RF signal versus fast time (19.45 µs/26.54 µs/32.79 µs corresponds to the front, mid and rear
boundaries). . (b) Mean of the signal. (c) Root mean square (RMS) of the noise. (d) Signal-to-noise ratio (SNR) with fast
time.
20 22 24 26 28 30 32 34
0
1
2
3
4
5
x 10
-4
Fast time (µs)
Amplitude(V)
c
RMS noise
20 22 24 26 28 30 32 34
0
2
4
6
8
10
12
x 10
-4
Fast time (µs)
Amplitude(V)
b
Mean signal
20 22 24 26 28 30 32 34
0
2
4
6
Fast time (µs)
SNR
d
(ii). Longer time experiment using porcine heart muscle and gelatin
sample without using plastic between samples

27. 27
(B). Amplitude versus slow time and their spectrums during electric
field
Figure: (a), (c) and (b), (d) are amplitude changes and frequency spectrums of porcine heart muscle windows 41
and 40 respectively.
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
a
Pork 41
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
x 10
-4
Frequency (Hz)
Amp,FFT
b
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
c
Pork 40
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
1
2
3
4
x 10
-4
Frequency (Hz)
Amp,FFT
d
Start of current — 184s
End of current — 1243s

28. 28
Amplitude versus slow time and their frequency spectrums during electric field
Continued..
Figure: (e), (g) and (f), (h) are amplitude changes and frequency spectrums of gelatin windows 83 and 86
respectively.
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
e
Gel 83
0 0.1 0.2 0.3 0.4 0.5
0
2
4
6
8
x 10
-5
Frequency (Hz)
Amp,FFT
f
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
g
Gel 86
0 0.1 0.2 0.3 0.4 0.5
0
1
2
3
4
x 10
-5
Frequency (Hz)
Amp,FFT
h

29. 29
3. Single Gelatin Experiment
(A) Ultrasound RF signal, mean of the signal, RMS noise and signal-to-noise ratio
0 20 40 60 80
-1
-0.5
0
0.5
1
Fast time (µs)
EchoAmplitude(mV)
a
20 22 24 26 28 30
0
1
2
3
4
5
6
x 10
-4
Fast time (µs)
Amplitude(V)
b
Mean signal
20 22 24 26 28 30
0
1
2
3
4
5
6
x 10
-4
Fast time (µs)
Amplitude(V)
c
RMS noise
20 22 24 26 28 30
0
1
2
3
4
5
Fast time (µs)
SNR
d
• SNR varies even in a homogeneous sample!
Figure: (a) Ultrasound RF signal with fast time (b) Mean of the signal (c) RMS of the noise (d) SNR with
fast time

30. 30
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
a
Gel 48
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
0.2
0.4
0.6
0.8
1
1.2
x 10
-4
Frequency (Hz)
SpectrumAmplitude
b
0 500 1000 1500
-1
-0.5
0
0.5
1
x 10
-3
Slow time(s)
Amplitude(V)
c
Gel 49
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
0
0.5
1
1.5
x 10
-4
Frequency (Hz)
SpectrumAmplitude
d
(B). Amplitude versus slow time and their spectrums during electric
field
Figure: (a), (c) and (b), (d) are the amplitude changes and frequency spectrums of the gelatin
windows 48 and 49 respectively
Start of current — 191s
End of current — 1251s

31. 31
Conclusions
• The effect of electric field in layered phantoms was quantified by finding the
frequency spectrums, mean amplitude of the signals, root mean square of the noise
and Signal-to-noise ratio . SNR was found to be the best measure to demonstrate
the current distribution in tissues and phantoms.
• The SNR was compared in both cases when the samples were separated and not
separated by the insulator (thin plastic). There was significant difference in SNR
between the different parts of the sample when there was insulator. However, the
difference is much smaller when there was no plastic between samples.

32. 32
Future Work
• In future, the two dimensional method, B-mode ultrasound can be investigated for the
better understanding of the EIMC SNR in tissue and samples during electric field
application.
• In the future study, it would be interesting to investigate quantitatively the
dependence of EIMC SNR on the current distribution in the samples. If the current
distribution in a sample can be measured, it is possible to reconstruct the electric
impedance of the sample, which can provide useful diagnostic information.

33. 33
Acknowledgements
Supervisor: Dr. Yuan Xu
Committee Members: Dr. Vladislav Toronov
Dr. Jahan Tavakkoli

34. 34
Thank you !