Signal Processing - March 2016 - 117

imaging is the capability of imaging at
a frame rate of up to tens of thousands
frames/second [5]. While such ultrafast
imaging technology offers great
opportunities for the improvement of
US imaging, especially for fast moving
objects such as a beating heart, arterial
flow, or a shear wave within the tissue
(based on which the tissue elasticity
can be quantified), it also raises significant challenges. Techniques to make
full use of the GB of data acquired per
second are required. There are opportunities to take advantage of the prior
knowledge in both the underlying
imaging physics and target tissue/
organ physiology, and to generate in
real-time clinically relevant information that are yet to be fully exploited.
In addition, the complex nonlinear
signals generated by MBs provide
another avenue for research, as the MB
signals can be influenced by many variables related to the in vivo environment,
such as blood pressure, proximity to vessel wall, gas saturation, and the mechanical properties of the surrounding tissue.
A better understanding of the physics
and advanced modeling and signal processing techniques could lead to extracting this clinically relevant information
from the MB signals. Additionally, while
most clinical US imaging is still in two
dimensions, three-dimensional US
imaging is arriving and will create further opportunities and challenges for
data postprocessing. Finally, molecular
imaging using targeted MBs is another
exciting area of further development,
where more advanced signal processing
could help detect and evaluate pathologies at their earliest stage.

Acknowledgments
We would like to thank Dr. Adrian Lim,
Prof. David Cosgrove, Prof. Roxy Senior,
and Yuanwei Li for providing some of
the clinical images used in this article;
Dr. Alfred Yu for providing the flow
phantom; and the U.K. Engineering and
Physical Sciences Research Council for
financial support (EP/M011933/1).

Authors
Antonio Stanziola (antonio.stanziola14@
ic.ac.uk) is a Ph.D. student with the
Ultrasound Laboratory for Imaging and
Sensing Group, Imperial College London.
Matthieu Toulemonde (m. toulemonde@
ic.ac.uk) is a postdoctoral researcher
with the Ultrasound Laboratory for
Imaging and Sensing Group, Imperial
College London.
Yesna O. Yildiz (y.yildiz11@ic.ac.uk)
is a Ph.D. student with the Ultrasound
Laboratory for Imaging and Sensing
group, Imperial College London.
Robert J. Eckersley (robert.eckersley@kcl.ac.uk) is a senior lecturer at
King's College London.
Meng-Xing Tang (mengxing.tang@
ic.ac.uk) is a reader (associate professor)
of biomedical imaging and the head of
the Ultrasound Laboratory for Imaging
and Sensing group, Department of Bioengineering, Imperial College London.

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