Zeike Taylor - Academia.edu (original) (raw)

Papers by Zeike Taylor

Journal of Magnetic Resonance, 2015

Nuclear magnetic resonance (NMR) has proven of enormous value in the investigation of porous medi... more Nuclear magnetic resonance (NMR) has proven of enormous value in the investigation of porous media. Its use allows to study pore size distributions, tortuosity, and permeability as a function of the relaxation time, diffusivity, and flow. This information plays an important role in plenty of applications, ranging from oil industry to medical diagnosis. A complete NMR analysis involves the solution of the Bloch-Torrey (BT) equation. However, solving this equation analytically becomes intractable for all but the simplest geometries. We present an efficient numerical framework for solving the complete BT equation in arbitrarily complex domains. In addition to the standard BT equation, the generalised BT formulation takes into account the flow and relaxation terms, allowing a better representation of the phenomena under scope. The presented framework is flexible enough to deal parametrically with any order of convergence in the spatial domain. The major advantage of such approach is to allow both faster computations and sensitivity analyses over realistic geometries. Moreover, we developed a second-order implicit scheme for the temporal discretisation with similar computational demands as the existing explicit methods. This represents a huge step forward for obtaining reliable results with few iterations. Comparisons with analytical solutions and real data show the flexibility and accuracy of the proposed methodology.

Journal of applied biomechanics

An important and longstanding field of research in orthopedic biomechanics is the elucidation and... more An important and longstanding field of research in orthopedic biomechanics is the elucidation and mathematical modeling of the mechanical response of cartilaginous tissues. Traditional approaches have treated such tissues as continua and have described their mechanical response in terms of macroscopic models borrowed from solid mechanics. The most important of such models are the biphasic and single-phase viscoelastic models, and the many variations thereof. These models have reached a high level of maturity and have been successful in describing a wide range of phenomena. An alternative approach that has received considerable recent interest, both in orthopedic biomechanics and in other fields, is the description of mechanical response based on consideration of a tissue's structure--so-called microstructural modeling. Examples of microstructurally based approaches include fibril-reinforced biphasic models and homogenization approaches. A review of both macroscopic and microstructural constitutive models is given in the present work.

Clinical employment of biomechanical modelling techniques in areas of medical image analysis and ... more Clinical employment of biomechanical modelling techniques in areas of medical image analysis and surgical simulation is often hindered by conflicting requirements for high fidelity in the modelling approach and high solution speeds. We report the development of techniques for high-speed nonlinear finite element (FE) analysis for surgical simulation. We employ a previously developed nonlinear total Lagrangian explicit FE formulation which offers significant computational advantages for soft tissue simulation. However, the key contribution of the work is the presentation of a fast graphics processing unit (GPU) solution scheme for the FE equations. To the best of our knowledge this represents the first GPU implementation of a nonlinear FE solver. We show that the present explicit FE scheme is well-suited to solution via highly parallel graphics hardware, and that even a midrange GPU allows significant solution speed gains (up to 16.4x) compared with equivalent CPU implementations. For the models tested the scheme allows real-time solution of models with up to 16000 tetrahedral elements. The use of GPUs for such purposes offers a cost-effective high-performance alternative to expensive multi-CPU machines, and may have important applications in medical image analysis and surgical simulation.

Studies in health technology and informatics

Finite element methods (FEM) have been used extensively within the field of surgical simulation t... more Finite element methods (FEM) have been used extensively within the field of surgical simulation to describe physically realistic interactions with soft-tissue organs. However, FEMs require researchers to balance computational costs against approximation techniques to maintain adequate performance. We aim to extend previous work in nonlinear FEM implementation with extensions which improve the performance of accurate modelling of multiple organs undergoing deformations.

Non-rigid registration is a tool commonly used in medical image analysis. However techniques are ... more Non-rigid registration is a tool commonly used in medical image analysis. However techniques are usually time consuming. In this paper we present a fast registration framework which is a modification of the well-known Free-Form Deformation (FFD) algorithm. Our algorithm uses the analytical Normalized Mutual Information gradient which leads to a highly parallel framework. Its implementation is therefore suitable for execution via Grapics Processing Units. We apply the new method to estimate the brain atrophy on Alzheimer's disease subjects and show that accuracy is similar to the classical FFD, however the computation time is dramatically decreased.

Non-rigid registration techniques are commonly used in medical image analysis. However these tech... more Non-rigid registration techniques are commonly used in medical image analysis. However these techniques are often time consuming. Graphics Processing Unit (GPU) execution appears to be a good way to decrease computation time significantly. However for an efficient implementation on GPU, an algorithm must be data parallel. In this paper we compare the analytical calculation of the gradient of Normalised Mutual Information with an approximation better suited to parallel implementation. Both gradient approaches have been implemented using a Free-Form Deformation framework based on cubic B-Splines and including a smoothness constraint. We applied this technique to recover realistic deformation fields generated from 65 3D-T1 images. The recovered fields using both gradients and the ground truth were compared. We demonstrated that the approximated gradient performed similarly to the analytical gradient but with a greatly reduced computation time when both approaches are implemented on the...

Journal of biomechanics, Jan 26, 2015

The personalization of trabecular micro-architecture has been recently shown to be important in p... more The personalization of trabecular micro-architecture has been recently shown to be important in patient-specific biomechanical models of the femur. However, high-resolution in vivo imaging of bone micro-architecture using existing modalities is still infeasible in practice due to the associated acquisition times, costs, and X-ray radiation exposure. In this study, we describe a statistical approach for the prediction of the femur micro-architecture based on the more easily extracted subject-specific bone shape and mineral density information. To this end, a training sample of ex vivo micro-CT images is used to learn the existing statistical relationships within the low and high resolution image data. More specifically, optimal bone shape and mineral density features are selected based on their predictive power and used within a partial least square regression model to estimate the unknown trabecular micro-architecture within the anatomical models of new subjects. The experimental re...

Lecture Notes in Computer Science, 2008

Accurate biomechanical modelling of soft tissue is a key aspect for achieving realistic surgical ... more Accurate biomechanical modelling of soft tissue is a key aspect for achieving realistic surgical simulations. However, because medical simulation is a multi-disciplinary area, researchers do not always have sufficient resources to develop an efficient and physically rigorous model for organ deformation. We address this issue by implementing a CUDA-based nonlinear finite element model into the SOFA open source framework. The proposed model is an anisotropic visco-hyperelastic constitutive formulation implemented on a graphical processor unit (GPU). After presenting results on the model's performance we illustrate the benefits of its integration within the SOFA framework on a simulation of cataract surgery.

Journal of applied biomechanics, 2006

An important and longstanding field of research in orthopedic biomechanics is the elucidation and... more An important and longstanding field of research in orthopedic biomechanics is the elucidation and mathematical modeling of the mechanical response of cartilaginous tissues. Traditional approaches have treated such tissues as continua and have described their mechanical response in terms of macroscopic models borrowed from solid mechanics. The most important of such models are the biphasic and single-phase viscoelastic models, and the many variations thereof. These models have reached a high level of maturity and have been successful in describing a wide range of phenomena. An alternative approach that has received considerable recent interest, both in orthopedic biomechanics and in other fields, is the description of mechanical response based on consideration of a tissue's structure--so-called microstructural modeling. Examples of microstructurally based approaches include fibril-reinforced biphasic models and homogenization approaches. A review of both macroscopic and microstru...

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2010

Reduced order modelling, in which a full system response is projected onto a subspace of lower di... more Reduced order modelling, in which a full system response is projected onto a subspace of lower dimensionality, has been used previously to accelerate finite element solution schemes by reducing the size of the involved linear systems. In the present work we take advantage of a secondary effect of such reduction for explicit analyses, namely that the stable integration time step is increased far beyond that of the full system. This phenomenon alleviates one of the principal drawbacks of explicit methods, compared with implicit schemes. We present an explicit finite element scheme in which time integration is performed in a reduced basis. The computational benefits of the procedure within a GPU-based execution framework are examined, and an assessment of the errors introduced is given. Speedups approaching an order of magnitude are feasible, without introduction of prohibitive errors, and without hardware modifications. The procedure may have applications in medical image-guidance pro...

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2010

We present a reduced order finite element (FE) algorithm suitable for real-time nonlinear simulat... more We present a reduced order finite element (FE) algorithm suitable for real-time nonlinear simulation of soft tissues. A dynamic FE formulation with explicit time integration is employed. We demonstrate significant computation acceleration by performing the time integration in a low-dimensional generalised basis, generated from a set of a priori training simulations. The key mechanism for the acceleration is the large increase in integration time step afforded by this means. Futhermore, we present a simple procedure for imposing inhomogeneous essential boundary conditions, thus overcoming one of the principal deficiencies of such approaches. The algorithm is described and demonstrated using an example neurosurgical simulation. The computation acceleration and errors introduced are examined.

Alzheimer's & Dementia, 2014

2011 International Conference on Digital Image Computing: Techniques and Applications, 2011

PET-MRI fusion is widely used in oncology for early tumour diagnosis, localisation and monitoring... more PET-MRI fusion is widely used in oncology for early tumour diagnosis, localisation and monitoring of therapy effects. Automatic extraction of the lesions on PET images is desirable, but remains problematic. Manual segmentation of PET images is time consuming, and restricts the definition of the tumour extent to some arbitrary threshold. This can be sub-optimal in brain tumour for instance, where tumour is diffused by nature. Moreover, when the tracer uptake is not limited to the invaded regions, it becomes more difficult for an expert to define a precise contour.

Lecture Notes in Computer Science, 2007

Clinical employment of biomechanical modelling techniques in areas of medical image analysis and ... more Clinical employment of biomechanical modelling techniques in areas of medical image analysis and surgical simulation is often hindered by conflicting requirements for high fidelity in the modelling approach and high solution speeds. We report the development of techniques for high-speed nonlinear finite element (FE) analysis for surgical simulation. We employ a previously developed nonlinear total Lagrangian explicit FE formulation which offers significant computational advantages for soft tissue simulation. However, the key contribution of the work is the presentation of a fast graphics processing unit (GPU) solution scheme for the FE equations. To the best of our knowledge this represents the first GPU implementation of a nonlinear FE solver. We show that the present explicit FE scheme is well-suited to solution via highly parallel graphics hardware, and that even a midrange GPU allows significant solution speed gains (up to 16.4x) compared with equivalent CPU implementations. For the models tested the scheme allows real-time solution of models with up to 16000 tetrahedral elements. The use of GPUs for such purposes offers a cost-effective high-performance alternative to expensive multi-CPU machines, and may have important applications in medical image analysis and surgical simulation.

IEEE Transactions on Medical Imaging, 2015

Spine-related disorders are amongst the most fre-quently encountered problems in clinical medicin... more Spine-related disorders are amongst the most fre-quently encountered problems in clinical medicine. For several applications such as 1) to improve the assessment of the strength of the spine, as well as 2) to optimize the personalization of spinal interventions, image-based biomechanical modeling of the verte-brae is expected to play an important predictive role. However, this requires the construction of computational models that are subject-specific and comprehensive. In particular, they need to incorporate information about the vertebral anisotropic micro-architecture, which plays a central role in the biomechanical function of the vertebrae. In practice, however, accurate person-alization of the vertebral trabeculae has proven to be difficult as its imaging in vivo is currently infeasible. Consequently, this pa-per presents a statistical approach for accurate prediction of the vertebral fabric tensors based on a training sample of ex vivo mi-cro-CT images. To the best of our knowledge, this is the first pre-dictive model proposed and validated for vertebral datasets. The method combines features selection and partial least squares re-gression in order to derive optimal latent variables for the predic-tion of the fabric tensors based on the more easily extracted shape and density information. Detailed validation with 20 ex vivo T12 vertebrae demonstrates the accuracy and consistency of the ap-proach for the personalization of trabecular anisotropy.

The Journal of Clinical Endocrinology & Metabolism, 2015

Context: Bone mass is low and fracture risk is higher in obese children. Hormonal changes in rela... more Context: Bone mass is low and fracture risk is higher in obese children. Hormonal changes in relation to skeletal microstructure and biomechanics have not been studied in obese children Objective: To ascertain the relationships of obesity-related changes in hormones with skeletal microstructure and biomechanics.

Studies in Mechanobiology, Tissue Engineering and Biomaterials, 2012

ABSTRACT Patients who undergo breast-conserving surgery frequently require more than one operatio... more ABSTRACT Patients who undergo breast-conserving surgery frequently require more than one operation as cancerous tissue may not be completely excised at the first attempt. Image-guidance which exploits the 3D information available in preoperative dynamic contrast enhanced (DCE) magnetic resonance (MR) images may help to reduce the re-excision rate. However, significant deformation of the soft tissue of the breast occurs between imaging and surgery because these DCE MR images must be acquired with the patient positioned prone, but surgery is performed supine. This limits the applicability of MR for guiding breast surgery. In this chapter we describe how a patient-specific biomechanical model, based on preoperative MR images, can assist in the task of locating the lesion in the operating theatre.

Lecture Notes in Computer Science, 2010

In this study, we investigated the applicability of a Graphics Processing Unit (GPU)-based dynami... more In this study, we investigated the applicability of a Graphics Processing Unit (GPU)-based dynamic explicit finite element (FE) program for fast quasi-static deformation simulations of breasts, and proposed an optimisation-based method to estimate material parameters of in vivo breast tissues in the context of nonlinear hyperelastic models. Due to its high-speed execution, the GPU-based FE program was used as a

Journal of Magnetic Resonance, 2015

Nuclear magnetic resonance (NMR) has proven of enormous value in the investigation of porous medi... more Nuclear magnetic resonance (NMR) has proven of enormous value in the investigation of porous media. Its use allows to study pore size distributions, tortuosity, and permeability as a function of the relaxation time, diffusivity, and flow. This information plays an important role in plenty of applications, ranging from oil industry to medical diagnosis. A complete NMR analysis involves the solution of the Bloch-Torrey (BT) equation. However, solving this equation analytically becomes intractable for all but the simplest geometries. We present an efficient numerical framework for solving the complete BT equation in arbitrarily complex domains. In addition to the standard BT equation, the generalised BT formulation takes into account the flow and relaxation terms, allowing a better representation of the phenomena under scope. The presented framework is flexible enough to deal parametrically with any order of convergence in the spatial domain. The major advantage of such approach is to allow both faster computations and sensitivity analyses over realistic geometries. Moreover, we developed a second-order implicit scheme for the temporal discretisation with similar computational demands as the existing explicit methods. This represents a huge step forward for obtaining reliable results with few iterations. Comparisons with analytical solutions and real data show the flexibility and accuracy of the proposed methodology.

Journal of applied biomechanics

An important and longstanding field of research in orthopedic biomechanics is the elucidation and... more An important and longstanding field of research in orthopedic biomechanics is the elucidation and mathematical modeling of the mechanical response of cartilaginous tissues. Traditional approaches have treated such tissues as continua and have described their mechanical response in terms of macroscopic models borrowed from solid mechanics. The most important of such models are the biphasic and single-phase viscoelastic models, and the many variations thereof. These models have reached a high level of maturity and have been successful in describing a wide range of phenomena. An alternative approach that has received considerable recent interest, both in orthopedic biomechanics and in other fields, is the description of mechanical response based on consideration of a tissue's structure--so-called microstructural modeling. Examples of microstructurally based approaches include fibril-reinforced biphasic models and homogenization approaches. A review of both macroscopic and microstructural constitutive models is given in the present work.

Clinical employment of biomechanical modelling techniques in areas of medical image analysis and ... more Clinical employment of biomechanical modelling techniques in areas of medical image analysis and surgical simulation is often hindered by conflicting requirements for high fidelity in the modelling approach and high solution speeds. We report the development of techniques for high-speed nonlinear finite element (FE) analysis for surgical simulation. We employ a previously developed nonlinear total Lagrangian explicit FE formulation which offers significant computational advantages for soft tissue simulation. However, the key contribution of the work is the presentation of a fast graphics processing unit (GPU) solution scheme for the FE equations. To the best of our knowledge this represents the first GPU implementation of a nonlinear FE solver. We show that the present explicit FE scheme is well-suited to solution via highly parallel graphics hardware, and that even a midrange GPU allows significant solution speed gains (up to 16.4x) compared with equivalent CPU implementations. For the models tested the scheme allows real-time solution of models with up to 16000 tetrahedral elements. The use of GPUs for such purposes offers a cost-effective high-performance alternative to expensive multi-CPU machines, and may have important applications in medical image analysis and surgical simulation.

Studies in health technology and informatics

Finite element methods (FEM) have been used extensively within the field of surgical simulation t... more Finite element methods (FEM) have been used extensively within the field of surgical simulation to describe physically realistic interactions with soft-tissue organs. However, FEMs require researchers to balance computational costs against approximation techniques to maintain adequate performance. We aim to extend previous work in nonlinear FEM implementation with extensions which improve the performance of accurate modelling of multiple organs undergoing deformations.

Non-rigid registration is a tool commonly used in medical image analysis. However techniques are ... more Non-rigid registration is a tool commonly used in medical image analysis. However techniques are usually time consuming. In this paper we present a fast registration framework which is a modification of the well-known Free-Form Deformation (FFD) algorithm. Our algorithm uses the analytical Normalized Mutual Information gradient which leads to a highly parallel framework. Its implementation is therefore suitable for execution via Grapics Processing Units. We apply the new method to estimate the brain atrophy on Alzheimer's disease subjects and show that accuracy is similar to the classical FFD, however the computation time is dramatically decreased.

Non-rigid registration techniques are commonly used in medical image analysis. However these tech... more Non-rigid registration techniques are commonly used in medical image analysis. However these techniques are often time consuming. Graphics Processing Unit (GPU) execution appears to be a good way to decrease computation time significantly. However for an efficient implementation on GPU, an algorithm must be data parallel. In this paper we compare the analytical calculation of the gradient of Normalised Mutual Information with an approximation better suited to parallel implementation. Both gradient approaches have been implemented using a Free-Form Deformation framework based on cubic B-Splines and including a smoothness constraint. We applied this technique to recover realistic deformation fields generated from 65 3D-T1 images. The recovered fields using both gradients and the ground truth were compared. We demonstrated that the approximated gradient performed similarly to the analytical gradient but with a greatly reduced computation time when both approaches are implemented on the...

Journal of biomechanics, Jan 26, 2015

The personalization of trabecular micro-architecture has been recently shown to be important in p... more The personalization of trabecular micro-architecture has been recently shown to be important in patient-specific biomechanical models of the femur. However, high-resolution in vivo imaging of bone micro-architecture using existing modalities is still infeasible in practice due to the associated acquisition times, costs, and X-ray radiation exposure. In this study, we describe a statistical approach for the prediction of the femur micro-architecture based on the more easily extracted subject-specific bone shape and mineral density information. To this end, a training sample of ex vivo micro-CT images is used to learn the existing statistical relationships within the low and high resolution image data. More specifically, optimal bone shape and mineral density features are selected based on their predictive power and used within a partial least square regression model to estimate the unknown trabecular micro-architecture within the anatomical models of new subjects. The experimental re...

Lecture Notes in Computer Science, 2008

Accurate biomechanical modelling of soft tissue is a key aspect for achieving realistic surgical ... more Accurate biomechanical modelling of soft tissue is a key aspect for achieving realistic surgical simulations. However, because medical simulation is a multi-disciplinary area, researchers do not always have sufficient resources to develop an efficient and physically rigorous model for organ deformation. We address this issue by implementing a CUDA-based nonlinear finite element model into the SOFA open source framework. The proposed model is an anisotropic visco-hyperelastic constitutive formulation implemented on a graphical processor unit (GPU). After presenting results on the model's performance we illustrate the benefits of its integration within the SOFA framework on a simulation of cataract surgery.

Journal of applied biomechanics, 2006

An important and longstanding field of research in orthopedic biomechanics is the elucidation and... more An important and longstanding field of research in orthopedic biomechanics is the elucidation and mathematical modeling of the mechanical response of cartilaginous tissues. Traditional approaches have treated such tissues as continua and have described their mechanical response in terms of macroscopic models borrowed from solid mechanics. The most important of such models are the biphasic and single-phase viscoelastic models, and the many variations thereof. These models have reached a high level of maturity and have been successful in describing a wide range of phenomena. An alternative approach that has received considerable recent interest, both in orthopedic biomechanics and in other fields, is the description of mechanical response based on consideration of a tissue's structure--so-called microstructural modeling. Examples of microstructurally based approaches include fibril-reinforced biphasic models and homogenization approaches. A review of both macroscopic and microstru...

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2010

Reduced order modelling, in which a full system response is projected onto a subspace of lower di... more Reduced order modelling, in which a full system response is projected onto a subspace of lower dimensionality, has been used previously to accelerate finite element solution schemes by reducing the size of the involved linear systems. In the present work we take advantage of a secondary effect of such reduction for explicit analyses, namely that the stable integration time step is increased far beyond that of the full system. This phenomenon alleviates one of the principal drawbacks of explicit methods, compared with implicit schemes. We present an explicit finite element scheme in which time integration is performed in a reduced basis. The computational benefits of the procedure within a GPU-based execution framework are examined, and an assessment of the errors introduced is given. Speedups approaching an order of magnitude are feasible, without introduction of prohibitive errors, and without hardware modifications. The procedure may have applications in medical image-guidance pro...

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2010

We present a reduced order finite element (FE) algorithm suitable for real-time nonlinear simulat... more We present a reduced order finite element (FE) algorithm suitable for real-time nonlinear simulation of soft tissues. A dynamic FE formulation with explicit time integration is employed. We demonstrate significant computation acceleration by performing the time integration in a low-dimensional generalised basis, generated from a set of a priori training simulations. The key mechanism for the acceleration is the large increase in integration time step afforded by this means. Futhermore, we present a simple procedure for imposing inhomogeneous essential boundary conditions, thus overcoming one of the principal deficiencies of such approaches. The algorithm is described and demonstrated using an example neurosurgical simulation. The computation acceleration and errors introduced are examined.

Alzheimer's & Dementia, 2014

2011 International Conference on Digital Image Computing: Techniques and Applications, 2011

PET-MRI fusion is widely used in oncology for early tumour diagnosis, localisation and monitoring... more PET-MRI fusion is widely used in oncology for early tumour diagnosis, localisation and monitoring of therapy effects. Automatic extraction of the lesions on PET images is desirable, but remains problematic. Manual segmentation of PET images is time consuming, and restricts the definition of the tumour extent to some arbitrary threshold. This can be sub-optimal in brain tumour for instance, where tumour is diffused by nature. Moreover, when the tracer uptake is not limited to the invaded regions, it becomes more difficult for an expert to define a precise contour.

Lecture Notes in Computer Science, 2007

Clinical employment of biomechanical modelling techniques in areas of medical image analysis and ... more Clinical employment of biomechanical modelling techniques in areas of medical image analysis and surgical simulation is often hindered by conflicting requirements for high fidelity in the modelling approach and high solution speeds. We report the development of techniques for high-speed nonlinear finite element (FE) analysis for surgical simulation. We employ a previously developed nonlinear total Lagrangian explicit FE formulation which offers significant computational advantages for soft tissue simulation. However, the key contribution of the work is the presentation of a fast graphics processing unit (GPU) solution scheme for the FE equations. To the best of our knowledge this represents the first GPU implementation of a nonlinear FE solver. We show that the present explicit FE scheme is well-suited to solution via highly parallel graphics hardware, and that even a midrange GPU allows significant solution speed gains (up to 16.4x) compared with equivalent CPU implementations. For the models tested the scheme allows real-time solution of models with up to 16000 tetrahedral elements. The use of GPUs for such purposes offers a cost-effective high-performance alternative to expensive multi-CPU machines, and may have important applications in medical image analysis and surgical simulation.

IEEE Transactions on Medical Imaging, 2015

Spine-related disorders are amongst the most fre-quently encountered problems in clinical medicin... more Spine-related disorders are amongst the most fre-quently encountered problems in clinical medicine. For several applications such as 1) to improve the assessment of the strength of the spine, as well as 2) to optimize the personalization of spinal interventions, image-based biomechanical modeling of the verte-brae is expected to play an important predictive role. However, this requires the construction of computational models that are subject-specific and comprehensive. In particular, they need to incorporate information about the vertebral anisotropic micro-architecture, which plays a central role in the biomechanical function of the vertebrae. In practice, however, accurate person-alization of the vertebral trabeculae has proven to be difficult as its imaging in vivo is currently infeasible. Consequently, this pa-per presents a statistical approach for accurate prediction of the vertebral fabric tensors based on a training sample of ex vivo mi-cro-CT images. To the best of our knowledge, this is the first pre-dictive model proposed and validated for vertebral datasets. The method combines features selection and partial least squares re-gression in order to derive optimal latent variables for the predic-tion of the fabric tensors based on the more easily extracted shape and density information. Detailed validation with 20 ex vivo T12 vertebrae demonstrates the accuracy and consistency of the ap-proach for the personalization of trabecular anisotropy.

The Journal of Clinical Endocrinology & Metabolism, 2015

Context: Bone mass is low and fracture risk is higher in obese children. Hormonal changes in rela... more Context: Bone mass is low and fracture risk is higher in obese children. Hormonal changes in relation to skeletal microstructure and biomechanics have not been studied in obese children Objective: To ascertain the relationships of obesity-related changes in hormones with skeletal microstructure and biomechanics.

Studies in Mechanobiology, Tissue Engineering and Biomaterials, 2012

ABSTRACT Patients who undergo breast-conserving surgery frequently require more than one operatio... more ABSTRACT Patients who undergo breast-conserving surgery frequently require more than one operation as cancerous tissue may not be completely excised at the first attempt. Image-guidance which exploits the 3D information available in preoperative dynamic contrast enhanced (DCE) magnetic resonance (MR) images may help to reduce the re-excision rate. However, significant deformation of the soft tissue of the breast occurs between imaging and surgery because these DCE MR images must be acquired with the patient positioned prone, but surgery is performed supine. This limits the applicability of MR for guiding breast surgery. In this chapter we describe how a patient-specific biomechanical model, based on preoperative MR images, can assist in the task of locating the lesion in the operating theatre.

Lecture Notes in Computer Science, 2010

In this study, we investigated the applicability of a Graphics Processing Unit (GPU)-based dynami... more In this study, we investigated the applicability of a Graphics Processing Unit (GPU)-based dynamic explicit finite element (FE) program for fast quasi-static deformation simulations of breasts, and proposed an optimisation-based method to estimate material parameters of in vivo breast tissues in the context of nonlinear hyperelastic models. Due to its high-speed execution, the GPU-based FE program was used as a