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PhD Project
HD  Ultrasound Elastography

Closing date of 2 July 2017 (Midnight BST)
Start date of September 2017

Overview

Introduction

We are seeking a PhD student to join the Noninvasive Surgery & Biopsy Laboratory at the Department of Bioengineering at Imperial College London and the Centre for Doctoral Training in Medical Imaging at King’s College London and Imperial College London. The project is to build the world's first high-definition ultrasound elastography technology.

Funding and Eligibility

Each studentship will be funded for 4 years. This includes tuition fees, stipends, and bench fees for a 1-year MRes followed by a 3-year PhD. Students will receive a tax-free stipend of ca. £16,000 per year. A generous allowance will be provided for research consumables and for attending UK and international conferences. Click for more details.

The funding supports Home/EU students with standard research council restrictions. EU students are only eligible for a full studentship if they have lived, worked or studied within the UK for 3 years prior to the funding commencing.

Closing date of 2 July 2017 (Midnight BST)

Start date of September 2017.


Project Description

Mechanical forces – the pulsing of blood, pumping of the heart, stretching and grabbing by immune cells – govern the daily life of our bodies. When the mechanics of a cell or tissue go awry, they give early clues to a developing disease – changes in blood flow is linked to atherosclerosis and changes in stiffness is linked to cancer metastasis. Catching these signs early could save lives by getting the right treatments to the patient before the disease becomes unmanageable.

The purpose of this PhD project is to create a new technology that can image changes in tissue elasticity in high-definition and with excellent sensitivity - enough to identify a disease before it gets nasty. This technology would be the world's first contrast-enhanced ultrasound elastography system.

Tissue elasticity is measured in 3 steps:

  1. Apply stress onto the tissue of interest
  2. Track the tissue deformation
  3. Extract elasticity measurements based on the deformation response

The student will create a technology that can perform this simple 3-step process, but 5 centimetres in the body and with a tiny 5 micrometre-in-diameter bubble.

The vision for this technology is as follows. Microbubbles – normally benign and inactive – will first be administered into the bloodstream with an intravenous injection. A wide ultrasound beam will then be emitted into the body using an acoustic array. As the ultrasound passes through the microbubbles, they will then activate and experience a primary Bjerknes force in the direction of the acoustic beam. The acoustically-driven bubbles will be used in step 1 to apply stress on the tissue of interest.  In step 2, ultrafast, super-resolution imaging technologies will be used to track the location of the bubble as it presses against the tissue. This data will then be processed in step 3, where mathematical models will be used to derive elasticity values. The end result, we hope, will be a hi-definition image of tissue elasticity.

This project is based on very new findings. Our work has been published in Applied Physics Letters (#1 journal in applied physics) and was the most read article in the Biophysics section of the journal [1]. Take a look at the supplementary videos located in the references of the applied physics site (Link).


FIGURES

Fig. 1. Experimental setup. A focussed transducer (5 MHz) driven by a function generator and power amplifier emitted ultrasound that converged to a small focal volume within a phantom. A wall-less tunnel within the phantom (1.2% gelatin) represented a physiologically relevant vessel in our body. The interaction of the ultrasound, microbubbles, and tissue were observed using a high-speed optical microscope (1,200 frames per second). [1]

Fig. 1. Experimental setup. A focussed transducer (5 MHz) driven by a function generator and power amplifier emitted ultrasound that converged to a small focal volume within a phantom. A wall-less tunnel within the phantom (1.2% gelatin) represented a physiologically relevant vessel in our body. The interaction of the ultrasound, microbubbles, and tissue were observed using a high-speed optical microscope (1,200 frames per second). [1]

Fig. 2. Feasibility of Acoustic Particle Palpation. A wall-less vessel phantom (1.2% gelatin) contained a dark dye with either (top row) water only or (bottom row) microbubbles (MBs). The images are zoomed into the focal volume (first column) before, (middle column) during, and (last column) after ultrasound (US) exposure (centre frequency: 5MHz, peak-negative pressure: 400kPa, pulse on time: 50 ms). US propagated left to right and produced (top row) no displacement with US alone, and (e) a large displacement with MBs. This is the first demonstration that acoustic particles can be used to palpate and measure tissue elasticity. [1]

Fig. 2. Feasibility of Acoustic Particle Palpation. A wall-less vessel phantom (1.2% gelatin) contained a dark dye with either (top row) water only or (bottom row) microbubbles (MBs). The images are zoomed into the focal volume (first column) before, (middle column) during, and (last column) after ultrasound (US) exposure (centre frequency: 5MHz, peak-negative pressure: 400kPa, pulse on time: 50 ms). US propagated left to right and produced (top row) no displacement with US alone, and (e) a large displacement with MBs. This is the first demonstration that acoustic particles can be used to palpate and measure tissue elasticity. [1]


Team

Supervisors

Dr. James J. Choi, Department of Bioengineering, Imperial College London
Dr. Robert Eckersley, Department of Biomedical Engineering, King's College London

Collaborators

Dr. Valeria Garbin, Department of Chemical Engineering, Imperial College London
Dr. Mengxing Tang, Department of Bioengineering, Imperial College London


Sought Candidate

We are seeking a passionate and capable individual who can work on a multi-disciplinary team to build this new technology. The work will involve physics – understanding how ultrasound pushes a microbubble (i.e., acoustic radiation force) against soft materials – and mechanical engineering – deriving elasticity values (e.g., Young’s Modulus). Experiments require concepts in computer engineering – using a high-speed camera (1 million frames per second) and developing methods to control and track the microbubble movement using an ultrasound transducer, a programmable ultrasound imaging engine, and advanced signal and image processing algorithms. We do not expect a single candidate to have all these skill, and so we encourage candidates from a broad range of backgrounds to apply (physics or any engineering discipline).



Key References

  1. Koruk H, El Ghamrawy A, Pouliopoulos AN, Choi JJ. Acoustic Particle Palpation for Measuring Tissue Elasticity. Appl Phys Lett. 107:223701. 2015. Link
  2. Christensen-Jeffries K, Browning RJ, Tang MX, Dunsby C, Eckersley RJ. In vivo acoustic super-resolution and super-resolved velocity mapping using microbubbles. IEEE Trans Med Imaging. 34(2):433-40. 2015.