REAL-PhD

Varga, Ádám

A helyi önkormányzáshoz való jog alapvető kérdései

Füzesi, Krisztián

TISSUE CHARACTERIZATION AND
CUSTOM MANUFACTURED PHANTOMS
FOR MODELLING OF MEDICAL
ULTRASOUND IMAGES
Krisztián Füzesi
Theses of the Ph.D. Dissertation
Supervisor: Dr. Miklós Gyöngy
Pázmány Péter Catholic University
Faculty of Information Technology and Bionics
Tamás Roska Doctoral School of Sciences and
Technology
Budapest, 2019

1 Introduction
A sound wave having a frequency over the range of human
perception (approxiamtely above 20 kHz) is called ultrasound
(US). In nature many animals use it for navigation, for example
bats or dolphins. Using this recognition the first technological
application was developed by Paul Langevin in 1917, where the
goal was the detection of submarines. [5]
Nowadays, US has a wide variety of applications such as non-
destructive testing, range finding, security systems, low energy
data-transfer, welding of plastic parts or biomedical applications.
[5–9]
In medicine US is one of the most widespread medical imaging
techniques. In medical imaging the frequency range of 1-20 MHz
is usually applied. Since penetration depth and resolution are
inversely proportional to each other, lower frequencies are used
where higher depths of penetration are required, while higher
frequencies will achieve higher resolution at the cost of limited
depth of penetration. The main advantage of using US is that it
is a non-invasive technique in the classical sense. Namely, only
heating and mechanical effects emerge as a safety issue during
examinations. Nevertheless, thermal and mechanical indices are
always kept under control and displayed on the screen during
operation of the imager. [5]
The most recent advances in technology enables us to acquire
high quality images (e.g. 4D fetal US). Furthermore, there are
several attempts to follow some treatments providing temper-
ature maps using US data [10–18]. However, without precise
models and measurements, development of these areas would be
impossible.
1
2 Challenges in Ultrasound
Phantom Manufacture
From the very beginning of medical imaging there had al-
ways been a need for test objects, which were usually placed in
baths filled with water. In US imaging, regularly placed string
or rod targets were imaged underwater to ensure standardized
results and eliminate artefacts of the equipment. As the resolu-
tion of these images improved along with hardware and software
solutions, the need for smaller and more precise targets emerged.
For example nowadays, a typical US calibration phantom
contains strings with a diameter smaller than 0.3 mm [19]. Also,
main characteristics of the propagation medium such as speed of
sound, attenuation and speckle density are well-adjusted. Never-
theless, as commercial phantoms are improving over time, their
price is also increasing. Moreover, commercial phantoms still of-
fer tissue models only on a macroscopic level which are best to
be used for the training of radiologists or calibration purposes
but are less useful in research and development (R&D) and in
the verification of the devices. [20]
These circumstances and the development attempts for spe-
cialized high frequency applications such as acoustic microscopy
as well as superficial US increase the demand for customizable
in-house solutions.
The main requirements for creating optimal custom manufac-
tured phantoms are high resolution (under 0.1 mm) at least in
2-dimensions; precise, reproducible placement of scatterers; and
reasonable acoustic properties for successful tissue mimicking.
Using conventional manufacturing methods one can only create
2
phantoms that are only mimicking tissues on a macroscopic level,
moreover in many cases only some of the acoustic properties can
be attained adequately. [20] For this reason, during the develop-
ment of an image enhancement algorithm, tests nowadays rely
on computer simulations and qualitative results obtained from
real US data.
Considering the temperature dependence of acoustic proper-
ties of tissues our knowledge is still insufficient, which shows the
necessity of further tissue charachterization as well.
In summary, the challenges in this field include the research
of still unavailable or uncertain acoustic properties of tissues,
searching for new, advanced materials which could be adequate
as a propagation medium and developing new types of in-house
phantom manufacturing methods. The current doctoral work
aims to further scientific knowledge in these topics by performing
tissue characterization of the temperature dependence of com-
mon ultrasonic parameters as well as by developing cost-effective
ultrasound phantom manufacturing technologies.
3
3 New Scientific Results
Thesis I: I characterized the propagation speed of sound
and acoustic attenuation, as well as the temperature dependence
of the aforesaid parameters in porcine myocardium. The results
confirm the feasibility of ultrasound in the monitoring of thermal
therapy and show what properties a realistic muscle-tissue model
should have.
Corresponding publication: [1]
The temperature dependence of soft tissue acoustic prop-
erties is relevant for monitoring tissue hyperthermia and also
when manufacturing customized tissue-mimicking ultrasound
phantoms.
Therefore I investigated the propagation speed and attenu-
ation of healthy porcine left ventricular myocardia (N = 5) in
a frequency range relevant for clinical diagnostic imaging, i.e.
2.5 − 13.0 MHz. Each tissue sample was held in a water bath
at a temperature T = 25 ◦C, heated to 45 ◦C, and allowed to
cool back down to 25 ◦C. Due to initial tissue swelling, the data
for decreasing temperatures was considered more reliable. In
this case, the slope of the phase velocity versus temperature
relation was measured to be 1.10 ± 0.04 m/s/ ◦C, and the slope
of the attenuation was 0.11 ± 0.04 dB/cm/ ◦C at 10 MHz,
or −0.0041 ± 0.0015 dB/cm/MHz1.4336/ ◦C as a function of
frequency.
4
Figure 1. Averaged phase velocity dispersion curves and attenuation
coefficients calculated over all samples in the frequency range of 2.5-
13.0 MHz. Red and blue colors indicate the data acquired during heating
and cooling of the surrounding medium, respectively. Dispersion of the
phase velocity is clearly visible and can be described by a linear function of
frequency with a slope of 0.2705 ± 0.042 m/s/MHz. The attenuation power
law coefficient n is 1.4336 ± 0.025.
5
Thesis II: I compared the feasibility of two rapid 3D-
prototyping methods in creating ultrasound phantoms. I have
shown that Fused Deposition Modelling (FDM) and Digital Light
Processing (DLP) are able to print ultrasound wire phantoms for
2D imaging at the resolution of 0.3mm, which is suitable for ul-
trasound imagers employing frequencies below 4 MHz.
Corresponding publication: [2]
Figure 2. Filament target phantoms bearing the letters “ITK” and
their US images. a) Technical drawing of the filament target phantom.
b1&b2) Acrylonitrile butadiene styrene (ABS) phantom and its US image.
c1&c2: Polylactic acid (PLA) phantom and its US image.
d1&d2: Photopolymer phantom and its US image.
US images were made after placing the phantoms in de-ionized water. The
pattern of letters “ITK” is clearly identifiable. However, there is evidence
of multiple reflections from each filament.
Recently, the use of 3D printing for manufacturing ultra-
sound phantoms has only emerged using expensive and complex
technology of photopolymer jetting. Keeping in mind the
modest means of many research laboratories, two reliable and
cost-effective 3D printing methods were developed for phantom
6
manufacturing, namely fused deposition modelling (FDM) and
digital light processing (DLP) techniques.
After successful trials, wire target phantoms were printed
and tested using both techniques. One photopolymer material
was used in the custom-manufactured DLP printer and several
other materials (ABS, PLA and thermoplastic urethane - TPU)
in the FDM printer. Except TPU, the results of the prints were
satisfactory and could be used as calibration phantoms, thus
the achievements were published.
Thesis III: I developed a method with which ultrasound
phantoms can be manufactured using Photopolymer Jetting tech-
nology.
The use of photopolymer jetting in the manufacture of
ultrasound phantoms has been shown previously by Jacquet et.
al. [21], however, a full description of the setup and parameters
used was lacking. I developed a method with which FC705
support material could be printed to be a suitable propagation
medium for ultrasound imaging. In my phantoms Vero White
Plus serves as the material of scatterers and the enclosing wall.
Thesis III.a.: I have shown that such phantoms can be
used to quantitatively test super-resolution algorithms.
Corresponding publication: [3]
Ultrasound images are usually covered with speckle noise.
This speckle pattern is originating from sub-wavelength scatter-
ers, however, it makes the images hard to interpret to the user,
moreover introduces additional uncertainty to measurements.
Super-resolution algorithms are aiming to improve image
7
quality and in parallel reduce measurement errors. Despite
the importance to have quantitative feedback, testing of these
algorithms usually includes only simulation results and presents
in-vivo examples in a qualitative fashion. Using my custom
manufactured phantoms I could measure quantitatively the
effect of a super-resolution algorithm on FWHM and RMSE
parameters of real ultrasound images.
B-mode Restored img. Restored img.
image (p = 0.5) (p = 2)
FWHMx (mm) 1.42 0.78 0.98
FWHMz (mm) 0.37 0.26 0.27
RMSE 2.34 1.87 1.93
Table 1. Axial and transverse full width at half maxima (FWHM)
values of a single scatterer from the outer frame of the phantom. The
results show an improvement in resolution using p = 0.5 and p = 2 norms.
Root mean square error (RMSE) values obtained using the inner random
scatterer pattern.
8
Figure 3. Scattering function of our phantom, the obtained B-mode
image and two resulting images of the algorithms using p = 0.5 and
p = 2 norm. It can be seen that the clusters of unresolvable scatterers in
the center region became distinguishable using both norms.
9
Thesis III.b.: I developed an algorithm with which arbi-
trary medical ultrasound images could be well (R2 ≥ 80 %) ap-
proximated and physically realized.
Corresponding publication: [4]
In ultrasound imaging current phantoms can mimic tissues
only on a macroscopic scale. One of the main reasons for this
is the lack of usage of 3D printing methods – and looking
into deeper, the lack of suitable 3D printing materials – in
phantom manufacture. Relying on the previous results using
photopolymer jetting technology I developed an iterative
algorithm (Stippling Algorithm - SA), which is able to calculate
the 2D (axial and lateral) position and intensity of scatterers
based on a post-beamformed RF ultrasound image. A further
advantage of the algorithm is that it is scalable to the resolution
of any 3D-printer.
Figure 4. SA results validated on a 3D printed phantom. Images show
the scattering function (SF), the original and resulting ultrasound images
of the 3D printed phantom. SA performed better than matching pursuit
(MP), even though for MP, local sparsity is not a requirement.
10
Figure 5. SA test results on a real US image. In this case an image of
a carotid artery is used. For this reason the original scattering function is
unknown. Despite the number of the scatterers on the Wiener-deconvolved
image is one magnitude larger than in the case of SA, the resulting US
image have nearly the same quality (R2 value) when comparing it to the
initial US image.
11
References
Publications of the author
[1] K. Füzesi, N. Ilyina, E. Verboven, K. V. D. Abeele, M. Gyöngy,
and J. D’hooge, “Temperature dependence of speed of sound
and attenuation of porcine left ventricular myocardium,” Ultra-
sonics, vol. 82, pp. 246–251, jan 2018.
[2] K. Füzesi and M. Gyöngy, “Comparison of two inexpensive
rapid prototyping methods for manufacturing filament tar-
get ultrasound phantoms,” Ultrasound in Medicine & Biology,
vol. 43, no. 3, pp. 712–720, mar 2017.
[3] K. Füzesi, A. Basarab, G. Cserey, D. Kouamé, and M. Gyöngy,
“Validation of image restoration methods on 3d-printed ultra-
sound phantoms,” in 2017 IEEE International Ultrasonics Sym-
posium (IUS). IEEE, sep 2017.
[4] K. Füzesi, Á. Makra, and M. Gyöngy, “A stippling algorithm
to generate equivalent point scatterer distributions from ultra-
sound images,” in Proceedings of Meetings on Acoustics 6ICU.
Acoustical Society of America, 2017.
12
Other references
[5] C. Hill, J. Bamber, and G. ter Haar, Physical Principles of
Medical Ultrasonics, 2nd ed. Wiley, New York, 2004.
[6] J. Tsujino et. al., “Ultrasonic plastic welding using fundamental
and higher resonance frequencies,” Ultrasonics, vol. 40, no. 1-8,
pp. 375–378, may 2002.
[7] R. Adhami and P. Meenen, “Fingerprinting for security,” IEEE
Potentials, vol. 20, no. 3, pp. 33–38, 2001.
[8] R. J. Przybyla, et. al., “In-air rangefinding with an AlN piezo-
electric micromachined ultrasound transducer,” IEEE Sensors
Journal, vol. 11, no. 11, pp. 2690–2697, nov 2011.
[9] S. C. Boon, et. al., “Method and apparatus for intra-body ul-
trasound communication,” Patent, Oct. 16, 2012, uS Patent
8,290,598.
[10] G. Menikou and C. Damianou, “Acoustic and thermal char-
acterization of agar based phantoms used for evaluating fo-
cused ultrasound exposures,” Journal of Therapeutic Ultra-
sound, vol. 5, no. 1, jun 2017.
[11] Y. Zhou, “Noninvasive thermometry in high-intensity focused
ultrasound ablation,” Ultrasound Quarterly, vol. 33, no. 4, pp.
253–260, dec 2017.
[12] A. A. Anosov, et. al., “Passive estimation of internal temper-
atures making use of broadband ultrasound radiated by the
body,” The Journal of the Acoustical Society of America, vol.
137, no. 4, pp. 1667–1674, apr 2015.
[13] A. Anosov, P. Subochev, A. Mansfeld, and A. Sharakshane,
“Physical and computer-based modeling in internal tempera-
ture reconstruction by the method of passive acoustic thermom-
etry,” Ultrasonics, vol. 82, pp. 336–344, jan 2018.
13
[14] E. S. Ebbini, C. Simon, D. Liu, “Real-time ultrasound thermog-
raphy and thermometry [life sciences],” IEEE Signal Processing
Magazine, vol. 35, no. 2, pp. 166–174, mar 2018.
[15] W. Kwiecinski, F. Bessière, E. C. Colas, W. A. N'Djin, M. Tan-
ter, C. Lafon, and M. Pernot, “Cardiac shear-wave elastography
using a transesophageal transducer: application to the mapping
of thermal lesions in ultrasound transesophageal cardiac abla-
tion,” Physics in Medicine & Biology, vol. 60, no. 20, p. 7829,
2015.
[16] C. H. Seo et. al., “The feasibility of using thermal strain imaging
to regulate energy delivery during intracardiac radio-frequency
ablation,” IEEE Transactions on Ultrasonics, Ferroelectrics
and Frequency Control, vol. 58, no. 7, pp. 1406–1417, jul 2011.
[17] P. Baki, S. J. Sanabria, G. Kosa, G. Szekely, and O. Goksel,
“Thermal expansion imaging for monitoring lesion depth us-
ing m-mode ultrasound during cardiac RF ablation: in vitro
study,” International Journal of Computer Assisted Radiology
and Surgery, vol. 10, no. 6, pp. 681–693, apr 2015.
[18] R. M. Arthur, W. L. Straube, J. W. Trobaugh, and E. G. Moros,
“Non-invasive estimation of hyperthermia temperatures with
ultrasound,” International Journal of Hyperthermia, vol. 21,
no. 6, pp. 589–600, sep 2005.
[19] M. M. Goodsitt, et. al., “Real-timeB-mode ultrasound quality
control test procedures. report of AAPM ultrasound task group
no. 1,” Medical Physics, vol. 25, no. 8, pp. 1385–1406, aug 1998.
[20] E. J. Boote, “Phantoms for ultrasound experimentation and
quality control,” in The Phantoms of Medical and Health
Physics. Springer New York, nov 2014, pp. 159–179.
[21] J.-R. Jacquet, F. Levassort, F. Ossant, and J.-M. Grégoire, “3d
printed phantom for high frequency ultrasound imaging,” in Ul-
trasonics Symposium (IUS), 2015 IEEE International. IEEE,
2015, pp. 1–4.
14



Tissue Characterization and Custom Manufactured Phantoms for Modelling of Medical Ultrasound Images

Fülöp, Tamás

Tér-időbeli vizuális jelenségek vizsgálata biológiai alapú algoritmusokkal

File, Bálint

Modular analysis of brain and free word association networks

Görög, Georgina

Sharing economy in the context of sustainable development – the empirical examination of the accomodation sharing

Bognár, Lajos

Illegális vagy vitatható kereskedelmi gyakorlatok fogyasztói megítélése

Jávor, Miklós

Egyházpolitika, ateista propaganda és békemozgalom a Kádár-rendszer korai éveiben (1957–1964) : Eszmetörténeti értekezés

Turi, Gergő

Quantifier Scope Ambiguities in Hungarian

Lo Giudice, Maria

Unravelling the role of Calcium sensing receptor (CaSR) in neurological phenotypes

Bencsik, Dóra

Hagyományos víztisztítási technológiák során visszamaradó melléktermék vegyületek vizsgálata halmodellen

Not a member yet