Three dimensional ultrasonic elasticity imaging

Lead Research Organisation: Institute of Cancer Research
Department Name: Division of Radiotherapy and Imaging

Abstract

Ultrasonic imaging is a safe, inexpensive way of looking inside thebody. Unfortunately, not everything shows up clearly in anultrasound scan. Tumours can be hard to see, becausethey often reflect sound in much the same way as the surroundingtissue. Even when they are detectable, their boundaries can beindistinct. This makes it difficult for surgeons to plan preciselywhat to cut out, or for clinicians to assess how well a tumour isresponding to treatment. However, tumours are often stiffer thantheir surroundings. If ultrasound could show the tissue'sstiffness, instead of the way it reflects sound, then tumours would bemuch easier to spot and delineate.This is what ultrasonic elastography sets out to achieve. There areseveral flavours of elastography, but we're going to focus on onewhich involves taking a series of conventional ultrasound pictureswhile the clinician presses down with varying pressure. If we comparetwo images in the sequence, stiff structures (like tumours) won'tchange much, whereas less stiff structures will be deformed. Imageprocessing algorithms can look at the two images and deduce thedeformation of each bit of tissue. We can therefore build up a map ofthe tissue's elasticity.Clinicians can already purchase equipment offering real-timeelastography, but what they get are two-dimensional (2D) pictures,corresponding to slices through the anatomy, and not a 3D map of thetissue's elasticity. Unfortunately, without the 3D map, it isdifficult to plan surgery and monitor a tumour's response totreatment. This is where this research proposal comes in. It bringstogether internationally leading groups in the areas of ultrasonicelastography (London) and 3D ultrasound (Cambridge) with the goal ofdeveloping 3D ultrasonic elastography.The research will progress on parallel high and low risk paths. Thelow risk work will look at ways of recording a series of 2Delastograms, at closely packed locations in space, and then stackingthem together to make a 3D image. We could get the clinician to sweepthe probe over the area of interest, recording elastograms all thewhile: this is the freehand approach. Or we could use a special 3Dprobe, inside which the innards of a 2D probe are mounted on a rockermechanism driven by a stepper motor. In this mechanical approach, theclinician holds the probe still, while the motor sweeps the beam overthe target area. We will implement both approaches and compare theireffectiveness in terms of imaging quality and ease of use. We willalso look at ways of exploiting the 3D nature of the data to improvethe clarity of the elastograms. This low risk research will interfaceclosely with the project's clinical objectives, to evaluate 3Delastography in the context of cancers of the breast andbrain. Feedback from the collaborating clinicians is important if theengineers are to develop technology which could actually affect theeveryday management of cancer patients.Meanwhile, the high risk path will attempt to build more detailedelastograms by measuring tissue deformation in 3D. Currently,elastography algorithms assess tissue deformation only in thedirection of the applied pressure. However, the tissue actuallydeforms in all three dimensions, and by measuring this weshould be able to make better elastograms and glean moreclinically useful information about the material's properties. Butmeasuring 3D deformation is hard, mostly because we can only make highresolution measurements in the direction of the ultrasound wave'spropagation, which is perpendicular to the skin surface. Tomeasure deformation in other directions, we will need tocontrol the ultrasound scanner to steer the waves moretangentially. Our aim is to image each bit of tissue from differentdirections while the applied pressure is varied. We will then need todevelop algorithms to deduce the 3D deformation from this rich data.

Publications

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Bamber JC (2008) Comment on new technology--ultrasound elastography. in Ultraschall in der Medizin (Stuttgart, Germany : 1980)

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Bamber JC (2012) Tissue motion assessment and biomechanical property imaging update (invited short-course) in Proc. IEEE International Ultrasonics Symposium

 
Description We developed successful hardware and software for three dimensional (3D) elastography, elucidating the relative merits of different ways of acquiring 3D data for computing elastograms, the qualitative and quantitative benefits of 3D elastography over 2D elastography. We also established novel methods for extracting 3D components of strain via ultrasound beam steering, imaging shear strain as well as normal strain, showed the benefits of these methods via finite element simulation and phantom experiments in characterising slippery tumour boundaries typical of benign versus invading malignant tumours, and confirmed these predictions via clinical trials in the context of breast tumours and brain tumours examined intraoperatively during tumour resection in a clinical context.
Exploitation Route The methods developed are currently limited by the available technology for 3D ultrasound data acquisition using mechanically swept probes. The findings provide a way forward that can be taken full advantage of with the forthcoming availability of full 2D matrix arrays and ultrafast data acquisition. With such emerging electronics and computing technology it will soon be time to return to this project and put into practice what we learned. This will lead to a truly next generation elastography and a genuine leap forward in medical diagnostic capability.
Sectors Healthcare,Manufacturing, including Industrial Biotechology,Retail

URL http://www.icr.ac.uk/our-research/research-divisions/radiotherapy-and-imaging/ultrasound-and-optical-imaging/research-projects
 
Description The 3D US tissue motion tracking and elastography methods developed were implemented for clinical use and preliminary trials were conducted for breast malignancy assessment and intraoperative use in image guided neurosurgery. Successful outcomes in the latter led to a follow-on project and collaboration at Queen Square Hospital in London, which is ongoing. The 3D tracking methods were adopted for use in motion monitoring in a further follow-on project for motion-adapted radiotherapy and in a collaboration with QMUL on use of strain imaging in early detection of tendon injury. 2D versions of the algorithms were implemented in a commercial medical ultrasound system (Zonare Medical Ltd.) and continues to be sold with royalties to the Institute of Cancer Research.
First Year Of Impact 2007
Sector Healthcare
Impact Types Societal,Economic

 
Description Advances in Physics for Precision Radiotherapy (Programme grant)
Amount £3,705,615 (GBP)
Funding ID C33589/A17616 
Organisation Cancer Research UK 
Sector Charity/Non Profit
Country United Kingdom
Start 12/2014 
End 11/2019
 
Description Biomedical Research Centre in Cancer (Royal Marsden NHS Foundation Trust) (Quantification Radiation Fibrosis)
Amount £102,014 (GBP)
Funding ID A59 
Organisation National Institute for Health Research 
Department NIHR Biomedical Research Centre
Sector Public
Country United Kingdom
Start 03/2015 
End 03/2017
 
Description Imaging approaches for delivery of personalized cancer treatment (Cancer Imaging Centre)
Amount £7,600,000 (GBP)
Funding ID C1060/A16464 
Organisation Cancer Research UK 
Sector Charity/Non Profit
Country United Kingdom
Start 12/2013 
End 11/2018
 
Description Institute of Cancer Research Studentship Extension grant (for L. Garcia)
Amount £22,245 (GBP)
Funding ID PhD student extension for fourth year 
Organisation Institute of Cancer Research UK 
Sector Academic/University
Country United Kingdom
Start 10/2010 
End 09/2011
 
Description Multi-modality functional imaging in cancer (Cancer Imaging Centre)
Amount £8,700,000 (GBP)
Organisation Cancer Research UK 
Sector Charity/Non Profit
Country United Kingdom
Start 12/2008 
End 11/2013
 
Description Multimodality techniques for cancer diagnosis and therapy (EPSRC Platform Grant)
Amount £1,656,697 (GBP)
Funding ID EP/H046526/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 10/2010 
End 09/2015
 
Description RCUK (Dorathy Hodgkin PG award)
Amount £128,000 (GBP)
Funding ID Dorathy Hodgkin Postgraduate Award (plus ICR-funded extension for 4th year) 
Organisation Research Councils UK (RCUK) 
Sector Public
Country United Kingdom
Start 02/2011 
End 02/2015
 
Description Whitaker Foundation Exchange Studentship
Amount £13,900 (GBP)
Organisation Whitaker International Program 
Sector Charity/Non Profit
Country United States
Start 10/2009 
End 09/2010
 
Description Nonlinear and anisotropic shear wave elastography (Uni Tours, E. Simon) 
Organisation François Rabelais University or University of Tours
Department Unité INSERM U-618
Country France 
Sector Academic/University 
PI Contribution Intellectual input, student supervision, research facilities, equipment, software, materials
Collaborator Contribution Intellectual input, conducting experimental research
Impact Conference presentation
Start Year 2015
 
Description OCT elastography with University of Western Australia 
Organisation University of Western Australia
Country Australia 
Sector Academic/University 
PI Contribution Intellectual input and advice on experimental elastography methods for application to optical coherence tomography research at University of Western Australia.
Collaborator Contribution Funding (via "Gledden Short Stay Fellowship", Institute for Advanced Studies, University of Western Australia, Perth) for visit to University of Western Australia, to engage in laboratory discussions, and discussions of possible joint grant applications.
Impact All invited presentations given at University of Western Australia listed under the honours and awards section of Researchfish for 2017.
Start Year 2017
 
Description Strain distributions as a novel indicator of tendon injury risk (with QMUL) 
Organisation Queen Mary University of London
Department School of Engineering and Materials Science
Country United Kingdom 
Sector Academic/University 
PI Contribution Intellectual input, student/post-doc supervision
Collaborator Contribution Intellectual input, conducting experimental research.
Impact No outputs yet.
Start Year 2016