Two weeks ago, during the Summer Biomechanics, Bioengineering, and Biotransport Conference (SB3C) in Vail, Colorado (USA) Leonardo Geronzi ESR 02 of the MeDiTATe project was awarded as one of the two Runner-Ups for the talk ‘Tuning of the mechanical boundary conditions parameters for a patient-specific thoracic aorta model’ 🏆🥈
Well done, Leonardo! 👏 👏 👏
We had a small talk with Prof. Kyriakos C. Giannakoglou, a member of the Board of the MeDiTATe project. He is a Professor at the School of Mechanical Engineering of the National Technical University of Athens (NTUA) and head of the Parallel CFD & Optimization Unit of the same School. His research interests include the development of CFD-based analysis and optimization methods and tools in fluid mechanics, incl. adjoint & evolutionary algorithms, extended to multi-disciplinary applications (aerostructural, aerothermal, aeroacoustic). His research group has developed the publicly available continuous adjoint for shape optimization in the OpenFOAM environment. In MeDiTATe, he is supporting/training ESR 04, ESR 05 and ESR 06 to extend/adapt an existing CFD software on GPUs, coupled with a structural analysis tool, to simulate aneurysm-related flows, at reduced cost, as a part of a digital twin. He has participated in numerous projects funded directly by the industry, as well as the EU, including eight MSCA ITNs. He has supervised 29 PhDs (accomplished) whereas 10 more are in progress.
Founded in 1837, the National Technical University of Athens (NTUA) is the oldest Technical University in Greece. NTUA participates into MeDiTATe through the Parallel CFD & Optimization Unit (PCOpt) of the School of Mechanical Engineering. The PCOpt/NTUA group comprises 15 research engineers developing, among other, CFD methods and software which are also ported onto HPC systems, including clusters of GPUs. For us, MeDiTATe was a great opportunity to see a portfolio of in-house tools being adapted to biomedical flows. The three ESRs associated with the PCOpt/NTUA had to use the in-house CFD code PUMA, written in C++/CUDA and accelerated on NVIDIA GPUs; next to PUMA, the three ESRs had also the chance to familiarize themselves with the open-access CFD software OpenFOAM; having access to two codes makes their life easier and gives them the possibility to make comparisons. Let me say a few things about the work of the three ESRs, one by one.
The objective of ESR 04 was to extend/integrate and use the CFD model to simulate the flow in aneurysms, assuming rigid walls, Newtonian and non-Newtonian fluids and variable viscosity. Flow computations using PUMA running on GPU clusters are fast, and this is challenging in the context of a digital twin. Studies are expected to lead to estimates of the aneurysm rupture risk, occurring when the stresses acting on the arterial wall exceed its failure strength. Next to them, Deep Neural Networks (DNNs) predict the failure points of the arterial wall, the origin and the progress of the aneurysms. ESR 05 extends the same background code to cope with moving walls, by incorporating a generic wall thickness model and Fluid-Structure Interaction (FSI) techniques. The structural problem within the solid region is solved using Finite Element Method (FEM) tools. A DNN is trained based on available real data to predict the cerebral aneurysm evolution and validate existing Fluid-Solid-Growth models of cerebral aneurysm evolution. Finally, the main objective of ESR 06 is to identify hemodynamic variables which are of greatest importance in aneurysm stabilization or rupture, through sensitivity studies. Uncertainty quantification (UQ) techniques are used for quantities of interest, such as the asymmetry metric, the saccular index, etc. The sensitivity of the simulation results changes in the input variable values are investigated. Shape imperfections and wall movement are realized by CAD-free techniques and a morphing/smoothing tool that adapts meshes to new boundary shapes.
The ultimate goal of the MeDiTATe network is the creation of Medical Digital Twins; to do so, several partners, from universities, research centres, hospitals and companies, with experience in the treatment of the cardiovascular diseases and patient care and numerical methods performing the solution of fluid problems interacting with the structural analysis of their vessels should join efforts; making these people work together was the first success of MeDiTATe. It is expected that the work done by the MeDiTATe ESRs will firstly lead to new findings in pure research and, then, will find its way in practical applications. The latter will be used to help scientists working for the treatment of cardiovascular diseases by offering state of the art tools for fast and accurate predictions, using simulations. Recall that the ultimate goal is to build a Medical Digital Twin.
The answer is definitely yes! For instance, the numerical simulation of the flow in blood vessels, including the more specific aneurysm studies, requires the availability of three tools: a CFD software for the analysis of flow patterns, a software for the structural analysis of the blood vessels walls (a FEM code) and, of course, a technique to make them cooperate by exchanging data, which is the so-called Fluid-Solid Interaction (FSI) technique. The literature is full of methods and tools developed for the accurate and efficient solution of all the above, developed in quite different application domains. As an example, FSI methods for use in aircraft applications are quite mature right now. With some add-ons that are really necessary if these methods are to be used in simulations, for instance, in aorta flows’, such as the use of a non-Newtonian fluid, these methods can readily be ported in the field of biomedical flows. We should also keep in mind that the majority of software developed for other engineering applications is already adequately parallelized and runs on HPC systems including clusters of GPUs. It is obvious that the type of applications MeDiTATe is dealing with can readily profit of all previous developments and achievements. This is where the three ESRs associated with the PCOpt/NTUA contributed to.
It is much easier for me to talk about the ESRs who worked with me in this project and spent 50% of their time in the PCOpt/NTUA. Having already exposed themselves in both the academic and industrial environment, they have already seen both sides; this is valuable piece of information that might help them, in the near future, to made decisions about the future steps in their career. While approaching the end of their involvement in MeDiTATe, I feel they have already learned a lot about the tools needed for these applications; they became familiar with CFD methods for the analysis of fluid flows, with FEM for the structural analysis and their interaction; they have extensively used them in an HPC environment, got results and know how to interpret them. They became ready to use these tools, but also any other similar tool they might have access to, for application regarding studies of aneurysms in an effort to build a digital twin, absolutely useful to people involved in the health sector. It is important that the three ESRs of PCOpt/NTUA were Mechanical Engineers and MeDiTATe managed to bridge the gap between the way engineers and medical scientists are facing this kind of problems.
If you are looking for a way to expose yourself simultaneously to the academic and non-academic sectors, if you wish to get high quality training on scientific/technical topics as well as transferable skills, if you are strongly interested in innovation and long-term employability, apply to a Marie Skłodowska-Curie Actions (MSCA) Innovative Training Network.
The MeDiTATe project was present at the International Conference on Computational Methods for Coupled Problems in Science and Engineering (COUPLED PROBLEMS 2023). The event took place on 5-7 June 2023 in Chania (Crete Island, Greece).
In this occasion Bhargav Krishna Chitneedi (ESR04) presented the results of its activities with the oral talk “Hemodynamic evaluation of aortic aneurysms using FSI simulations”. A short abstract of the work is as follows:
Understanding the dynamics of aortic blood flow plays a vital role for the assessment of cardiovascular health for identifying potential risk factors for diseases like aneurysm, thrombosis etc. Fluid structure interaction (FSI) can be used to study the aortic blood flow and how this is affected by the mechanical properties of the aortic wall, such as its stiffness and compliance. The results of FSI simulations can provide insight into the factors that contribute to aortic blood flow patterns and predict failures which might be the reason for cardiovascular diseases.
Leonardo Geronzi ESR 02 of the MeDiTATe project has been selected as one of the finalists for the SB3C PhD level award competition in the context of the Summer Biomechanics, Bioengineering, & Biotransport Conference (SB3C). The event takes place during these days (4 – 8 June 2023) at the Grand Hyatt Vail, Colorado.
The work presented by Leonardo Geronzi “Tuning of the mechanical boundary conditions parameters for a patient-specific thoracic aorta model” presents a procedure to tune the parameters controlling the mechanical boundary conditions (BCs) of a thoracic aorta (TA) model in fluid-structure interaction analysis. These parameters specifically account for the displacement caused by the heart at the level of the aortic annulus. The mechanical BCs introduced consist of a group of viscoelastic components that represent the support provided by the soft tissue and replicate the interaction between the aorta and the spine. By exploiting the information derived from 2D cine-MRI sequences, the parameters governing the BCs are calibrated to achieve a better correspondence between the displacement of the simulated model and the displacement derived from the images.
Congratulations Leonardo Geronzi and fingers crossed! 🤞
The MeDiTATe project will be present at the Summer Biomechanics, Bioengineering, & Biotransport Conference (SB3C). The event will take place on 4 – 8 June 2023 at the Grand Hyatt Vail, Colorado.
In this occasion four Early-Stage Researchers (ESRs) will be presenting the results of their activities:
Leonardo Geronzi – ESR 02: Tuning of the mechanical boundary conditions parameters for a patient-specific thoracic aorta model. This work presents a procedure to tune the parameters controlling the mechanical boundary conditions (BCs) of a thoracic aorta (TA) model in fluid-structure interaction analysis. These parameters specifically account for the displacement caused by the heart at the level of the aortic annulus. The mechanical BCs introduced consist of a group of viscoelastic components that represent the support provided by the soft tissue and replicate the interaction between the aorta and the spine. By exploiting the information derived from 2D cine-MRI sequences, the parameters governing the BCs are calibrated to achieve a better correspondence between the displacement of the simulated model and the displacement derived from the images.
Beatrice Bisighini – ESR 03: Machine Learning-Based Reduced Order Modelling For The Simulation Of Braided Stent Deployment. This work presents a machine learning-based reduced-order model scheme, trained on finite element simulations, to compute the deployed configuration of flow diverters within patient-specific models in real-time. Flow diverters are very dense braided stents used in the endovascular treatment of cerebral aneurysms. Computational tools could be useful in assisting surgeons in the selection of the best device for a patient, especially in complex cases. However, due to the large amount of degrees of freedom and the necessity to solve the contact with the wall, the computational time required by traditional techniques alone, such as finite element modelling, is excessively high. Machine learning-based reduced order modelling can enable real-time prediction while retaining the mechanical realism and predictability of the stent deployed configuration.
Federica Galbiati – ESR 07: Investigating the role of eccentric inlet conditions on hemodynamic results at different stages of aneurysm growth. Ascending thoracic aortic aneurysm (aTAA) is a life-threatening condition whose etiology is still unknown, but the link between altered aortic hemodynamics and aTAA development is widely recognized. In particular, alterations induced by the presence of a bicuspid aortic valve (BAV) with consequent eccentricity of aortic inlet flow seems to play a role in the highest prevalence of aTAA cases in these patients, compared to subjects with a tricuspid aortic valve (TAV). In the state of the art, different groups have focused on the analysis of TAV and BAV influence on aortic hemodynamics by using patient specific geometries and inlet conditions. However, perspective studies that investigate the evolution of hemodynamics patterns in presence of TAV or BAV phenotypes concurrently with aTAA progression are still limited. Therefore, the main goal of this study is to investigate the role of inlet conditions eccentricity in the hemodynamics results at different stages of aTAA, accounting different configurations of TAV and BAV.
Francesco Bardi – ESR 10: Validation of FSI simulations against a compliant aortic phantom in a Hybrid Mock Circulatory Loop. Computational fluid dynamics (CFD) is a widely used tool in research to improve the understanding of various cardiovascular diseases. Fluid Structure Interaction (FSI) simulations consider the motion of the vessels, providing a more accurate solution for the evaluation of blood velocity and pressure fields. The aim of this work is to perform a rigorous in-vitro validation of the FSI coupled momentum method using a flexible thoracic aortic phantom. A novel Hybrid Mock Circulatory Loop (HMCL) was used to replicate different physiological conditions in the flexible phantoms and the gathered experimental data were compared with the results of the numerical simulations.
Recently the ESR09 Martino Andrea Scarpolini presented the results of his activities in the context of the MeDiTATe project at the Workshop “Biomeccanica dei trattamenti endovascolari”. The workshop took place on the 9th of May 2023 at the University of Pavia, Italy.
The title of the talk is “Data-Driven FSI simulation of Ventricle and Aorta integrating in vivo and in silico data”.
An abstract describing the presented work is reported below:
“The integration of in silico and in vivo data is crucial to the development of high-fidelity digital twins of the cardiovascular (CV) system but is a challenging task that requires specific imaging techniques and in silico setups. Advancements in imaging technologies are making it possible to gather a large amount of patient information. In parallel, in silico models are becoming a useful tool to simulate patient-specific conditions, treatments and therapies. However, the latter models require a large amount of physical parameters to be known, which are often very difficult to measure in vivo. In this study, we used data-assimilation techniques to merge high-resolution temporal CT scans with fluid structure interaction (FSI) simulations, resulting in the creation of a high-fidelity digital twin of the left ventricle (LV) and aorta system of a patient.”
The second MeDiTATe project newsletter is out! It contains main news, latest events and much more of the activities carried out in the first months of 2023.
The newsletter can be downloaded at the following link: MeDiTATe Newsletter #2 May 2023.
A new paper Machine learning and reduced order modelling for the simulation of braided stent deployment has been published in the Frontiers in physiology Journal. The paper was written by Beatrice Bisighini ESR 03 as well as by authors from the MeDiTATe project including Marco Evangelos Biancolini, Principal Investigator of the MeDiTATe project, and Stéphane Avril, Research Coordinator of MeDiTATe project. Read More
The MeDiTATe project was present at the MASH’s congress. The event took place on 4 – 6 May 2023 at the University of Corsica in Bastia, France. In this occasion two Early-Stage Researchers (ESRs), ESR 01 Antonio Martinez Pascual and ESR 02 Leonardo Geronzi, had the opportunity to present their research findings and share them with colleagues from around the world with a joint talk whose title is “Ascending aortic aneurysm growth prediction based on shape and fluid-dynamics biomarkers”. Read More
