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CURRENT RESEARCH PROJECTS

Project

Project

Project Outline

Many of our research projects cut across each of our research themes and also span engineering, medicine and science. We have many projects underway and only some are presented here.
Currently, the primary themes of research at VascLab are:
Aortic aneurysm
Aortic dissection
Coronary artery disease
Placenta
Cerebrovascular
Tissue engineering

Within each theme, we have a wide range of research projects underway. Typically we use a combination of imaging, computational and experimental techniques to answer basic questions about physiology or develop new ways to understand and treat disease.

CURRENT STUDENT PROJECTS

Student Project

Abdominal aortic aneurysm (AAA) rupture risk assessment

Student Project

Abdominal aortic aneurysm (AAA) rupture risk assessment

Project Outline

The current method used to determine if an AAA is at risk of rupture is to measure the maximum diameter using medical imaging. AAAs bigger than 5 - 5.5cm in diameter are considered at risk, and the patient will usually be offered surgery. However, smaller AAAs can rupture and larger ones often remain stable and may never rupture. Therefore, can we predict which patients would benefit from surgery? We believe so.

As part of this long-running project, and through generous funding from the NHMRC, we have recently developed a new method to predict the risk of rupture. This method has been refined into a freely available software pipeline called BioPARR – Biomechanics based Prediction of Aneurysm Rupture Risk.

Our approach overcomes some of the key obstacles that were hindering clinical implementation, namely the uncertainty in aneurysmal wall thickness and lack of knowledge of patient-specific material properties. We begin by registering CT and MRI together to create our 3D reconstructions and then apply a novel solid mechanics approach to determine the stresses in the vessel. We are now testing our approach on a large number of patients to demonstrate that 3D biomechanics-based methods outperforms the current 2D diameter approach, and provides a real benefit to patient care.

This figure shows how we predicted the exact location of rupture 4 months before the rupture actually happened. In this case, the patient refused surgery and was then repaired after his AAA ruptured.

Vascular haemodynamics
We are very interested in the nature of blood flow in both healthy and diseased arteries. We use computational fluid dynamics (CFD) to simulate the haemodynamics in a wide range of anatomical regions at all sizes scales. Understanding the nature of the blood flow and the data than can be derived from the flow, such as wall shears stress, can significantly help towards developing new treatments, design new medical devices and further our knowledge as to why and how haemodynamics impacts the development of healthy and diseased arteries.
The figure shows the dispersion of platelets and monocytes over the cardiac cycle within an isolated iliac artery aneurysm. As the particles changes colour, they are staying in the system longer.

Haemodynamics in the placental vasculature
This project investigates the placental vasculature of mice. We simulate the haemodynamics using physiological inputs to our models and compute the wall shear stresses. The figure shows the shear stress in the upper branches of the network which form the start of a much larger, dense network of intraplacental vessels. This information can be used to determine nitric oxide (NO) production and also the transport of oxygen and nutrients. The red arrows indicate the direction of flow.

Where and why do aneurysms develop?
Aneurysms are prone to develop in certain anatomical regions, such as the abdominal aorta. But why are they so common here? We try answer this, and other questions, by simulating the blood flow in the region and by designing studies that investigate a range of potential geometric variations and the impact of blood flow. The iliac arteries are a somewhat unique anatomical region to help our understanding and we are currently determining why the internal iliac artery is prone to aneurysmal disease, yet the external iliac artery is not.

This video shows the velocity-coloured flow over the cardiac cycle entering the sac of an iliac artery aneurysm and clearly demonstrates the cyclic impingement of blood onto the far side of the sac. This impingement is where the aneurysm later ruptured.

Type B aortic dissection
There is little evidence indicating which cases of Type B aortic dissection (AD) should be repaired and which should be conservatively managed via medication. This is primarily because it is difficult for clinicians to predict which cases will develop complications and thus require surgery. Recent evidence indicates that CFD-derived data, such as wall shear stress, can predict complications. We have shown in single case studies that our methods highlight the areas of rapid aortic expansion (an established complication and marker of repair). In this project we are expanding our knowledge in this area and combining new imaging methods to help identify patients at risk.
The first figure shows a reconstruction of a case of type B AD and the second one shows the evolution of intramural haematoma, a condition often associated with aortic dissection. The models are 3D reconstructions from CT at several time points in the early care of the patient.

We then compute the haemodynamics and wall shear stress and return it to the clinician in an easy to interpret format with full 3D manipulation.



Retinal vasculature

CVD often manifests in the microcirculation long before it show signs in the larger arteries. The retina is one of the few places that the microvasculature can be observed non-invasively. In this project, we take standard fundus photographs of the retina and convert them into computational models.

The image shows the process from fundus image (left) to velocity simulation (right).

Soft tissue biomechanics

How vessels and other cardiac tissue behave when subjected to mechanical stimulus is central to many aspects of CVD. We know that arteries stiffen as we age, but by how much? And how much does my artery differ in mechanical behaviour than yours? What about plaques and thrombus that build up within our arteries as we get older? How do they behave? And how does inflammation, calcification and other biological processes impact mechanical behaviour?
These questions can be answered by biomechanically testing tissue from either patients undergoing surgery or from animal models. We use various forms of biomechanical experimentation to measure mechanical properties such as stiffness and strength. At VascLab we have apparatus capable of uniaxial and biaxial tensile testing, as well as pressure-diameter testing.

The figure shows intraluminal thrombus which is present in most clinically-relevant aortic aneurysms. We can separate the tissue into its layers and biomechanically tensile test each layer. This allows us to measure the stiffness and strength. One application of this data is to better inform our computational models.

3D bioprinting
The combination of 3D printing with existing tissue engineering strategies has opened the door for many new applications. We are currently exploring the use of 3D bioprinting for several different applications with the hope of one day being able to print patient-specific body parts for implantation.

Student project opportunities
We have many different opportunities for students to get involved at undergrad, Master and PhD level. If any of the current research areas are of interest to you, please get in touch with Barry to learn more.

Project suitable for
Undergraduate, Masters and PhD

Student Project

Aortic dissection

Student Project

Aortic dissection

Project Outline

Aortic dissection occurs typically when there is a tear in the innermost layer of the aortic wall that allows blood to pass into the middle layers. Although this is a medical emergency, many cases can be managed with medication, but there are no current methods that can predict which patients will go on to develop complications. Our research focuses on the prediction of complication events.
Through the application of computational fluid dynamics we are developing tools to quantify patient-specific haemodynamics. These data are then combined with known risk predictors like aortic diameter and the degree of false lumen thrombosis to provide a complete patient-specific risk score.
Student project opportunities
We have many different opportunities for students to get involved at undergrad, Master and PhD level. If any of the current research areas are of interest to you, please get in touch with Barry to learn more.

Student Project

Coronary artery disease

Student Project

Coronary artery disease

Project Outline

At VascLab we are merging our computational biomechanics expertise with modern cardiovascular imaging modalities to improve the risk stratification methods used in the prognosis of coronary artery disease. In close collaboration with Prof. Carl Schultz and his team at the Royal Perth Hospital, we are linking patient-specific fluid and structural mechanical behaviour with novel cardiovascular disease biomarkers.
The ability to identify vulnerable plaque is a urgent clinical need. Coupling both Sodium-Fluoride Positron Emission Tomography (NaF PET) and Optical Coherence Tomography (OCT) imaging makes the early detection and characterisation of high-risk plaques possible, while we also reveal the physical environment a plaque endures in vivo. We believe this provides an unrivalled perspective on coronary artery disease progression.

Student project opportunities
We have many different opportunities for students to get involved at undergrad, Master and PhD level. If any of the current research areas are of interest to you, please get in touch with Barry to learn more.

Student Project

Placenta

Student Project

Placenta

Project Outline

In collaboration with the Wyrwoll Lab at the UWA School of Human Sciences and CMCA, our research uses experimental, imaging and computational modelling to assess structure, haemodynamics and function over pregnancy, in both healthy development and fetal growth restriction.
The placenta is a transient organ which develops during pregnancy to support healthy fetal growth and development through exchange of oxygen, nutrients and waste between the mother and fetus. Fundamental to its function is the healthy development of vascular trees in the feto-placental arterial network. Optimal vascular development critically depends on mechanotransduction, the sensing of shear stress by specialised receptors inside blood vessels to promote angiogenesis, remodelling and proliferation. Our research in this area uses experimental and computational techniques to assess structure, haemodynamics and function over pregnancy, in both healthy development and fetal growth restriction (FGR).

Eventually, we hope to understand the implication of the placental haemodynamic load on fetal tissue growth and cardiac development. Our framework enables us to explore the antenatal diagnostic potential of placental vasculature in FGR as well as the in-silico design of new therapeutic approaches.

Student project opportunities
We have many different opportunities for students to get involved at undergrad, Master and PhD level. If any of the current research areas are of interest to you, please get in touch with Barry to learn more.

Student Project

Tissue engineering

Student Project

Tissue engineering

Project Outline

3D-bioprinting is an emerging, innovative area of 3D-printing that involves printing with live cells embedded into a biomaterial. This represents considerable complexities, such as the choice of material, cell line and many technical challenges in order to biofabricate tissue. 3D-bioprinting requires the integration of technologies from engineering, biomaterials science, biology, physics and medicine. It is hoped that one day 3D-bioprinting will enable us to print fully functional human organs ready for implantation into a patient.
In our group, different strategies are being developed to enhance the performance of bioinks and, consequently, to improve the design of new scaffolds and structures. Our goal is to develop bioprinted materials which could mimic human tissue for repairing or replacing damaged tissue.

We are currently working on tendon regeneration by using a hybrid technology of FDM 3D printing and 3D bioprinting. Tendon pathology occurs most frequently in sports-related injuries, such as the Achilles tendon rupture, which is one of the most injured tendons in the body often due to long-term overuse and repetitive activities. We aim to produce and evaluate a novel range of biodegradable scaffolds with sophisticated mechanical and physico-biochemical properties to resemble the native tendon tissue. We work closely with our industrial partner Orthocell on this project, through the ARC Centre for Personalised Therapeutics Technologies.

Student project opportunities
We have many different opportunities for students to get involved at undergrad, Master and PhD level. If any of the current research areas are of interest to you, please get in touch with Barry to learn more.

Student Project

Cerebrovascular

Student Project

Cerebrovascular

Project Outline

The circular loop of arteries that supply blood to the brain and surrounding tissue is known as the Circle of Willis (CoW). These arteries control brain blood flow and are regulated by multiple factors. Despite the critical role of the CoW, over 50% of the population have at least one artery missing or underdeveloped. Together with Prof. Danny Green and our collaborators in the School of Human Sciences at UWA, we are exploring the structural and functional differences of the CoW.
We do this by imaging subjects using MRI and measuring blood flow in the carotid and vertebral arteries using Doppler ultrasound, and within the CoW using transcranial Doppler. These data are coupled together to perform high-fidelity computational fluid dynamics simulations. We aim to fully understand the role of shear stress and vascular adaptation in this amazing network of critical blood vessels.

Student project opportunities
We have many different opportunities for students to get involved at undergrad, Master and PhD level. If any of the current research areas are of interest to you, please get in touch with Barry to learn more.