Search results for: Poul M.F. Nielsen

Items from 1 to 18 out of 18 results

article

Is it time to rethink using digital palpation for assessment of muscle stiffness?

Melissa J. Davidson, Poul M.F. Nielsen, Andrew J. Taberner, Jennifer A. Kruger

Neurourology and Urodynamics > 39 > 1 > 279 - 285

Aim Physiotherapists typically use digital palpation to determine residual tension in a muscle, referred to as muscle stiffness or tone. These assessments are subjective, and little is known about their accuracy or repeatability. Despite this, it is standard practice to base clinical treatment on these findings. The aim of this study was to assess physiotherapists’ ability to assign a seven‐point...

article

Characterizing levator‐ani muscle stiffness pre‐ and post‐childbirth in European and Polynesian women in New Zealand: a pilot study

Jennifer A. Kruger, Stephanie C. Budgett, Vivien Wong, Poul M.F. Nielsen, more

Acta Obstetricia et Gynecologica Scandinavica > 96 > 10 > 1234 - 1242

Introduction The influence of levator‐ani muscles on second‐stage labor is poorly understood. The ability of these muscles to stretch without damage may affect birth outcomes, but little is known about material properties, effects of pregnancy and/or ethnicity on levator‐ani stiffness. There are strong associations between muscle damage and subsequent pelvic floor disorders. This study aimed to quantify...

article

Four-Dimensional Imaging of Cardiac Trabeculae Contracting In Vitro Using Gated OCT

Ming L. Cheuk, Alexander J. Anderson, June-Chiew Han, Norman Lippok, more

IEEE Transactions on Biomedical Engineering > 2017 > 64 > 1 > 218 - 224

Cardiac trabeculae are widely used as experimental muscle preparations for studying heart muscle. However, their geometry (diameter, length, and shape) can vary not only among samples, but also within a sample, leading to inaccuracies in estimating their stress production, volumetric energy output, and/or oxygen consumption. Hence, it is desirable to have a system that can accurately image each trabecula...

chapter

Light source depth estimation in porcine skin using spatially resolved diffuse imaging

Kieran A. Brennan, Bryan P. Ruddy, Poul M.F. Nielsen, Andrew J. Taberner

2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) > 5917 - 5920

2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

We present an inexpensive imaging system for measuring the diffuse surface radiance profile produced by a light source within a turbid medium. The diffusion model of light propagation in multiple scattering media is used to estimate the optical properties of a sample and subsequently approximate the depth of an optical source. The system is shown to accurately estimate the relative changes in source...

chapter

Mapping Microcalcifications Between 2D Mammograms and 3D MRI Using a Biomechanical Model of the Breast

Vijay Rajagopal, Jae-Hoon Chung, Ralph P. Highnam, Ruth Warren, more

Computational Biomechanics for Medicine > Computational biomechanics of soft tissues and flow > 17-28

We propose a method to localise the 3D positions of microcalcifications found in X-ray mammograms using the 3D breast modelling framework of Chung et al. [1]. The accuracy of the method was first studied using a phantom embedded with X-ray visible beads. The phantom was subjected to mammographic-like compressions and imaged under X-ray to determine the positions of the beads. Using these data as inputs,...

chapter

Effects of Fetal Head Motion on Pelvic Floor Mechanics

Xinshan Li, Jennifer A. Kruger, Martyn P. Nash, Poul M.F. Nielsen

Computational Biomechanics for Medicine > Computational biomechanics of tissues of musculoskeletal system > 129-137

We have developed a modelling framework to simulate vaginal delivery using individual-specific pelvic floor geometries derived from magnetic resonance images, which could potentially be used to study the effect of various contributing factors (such as muscle mass and muscle tone) on the childbirth process. One important goal of this is to faithfully represent the path of the fetal head as it descends...

chapter

Method for Validating Breast Compression Models Using Normalised Cross-Correlation

Angela W.C. Lee, Vijay Rajagopal, Jae-Hoon Chung, Poul M.F. Nielsen, more

Computational Biomechanics for Medicine > Computational biomechanics of soft tissues and flow > 63-71

To diagnose and manage breast cancer, X-ray mammography, ultrasound, and magnetic resonance (MR) imaging are used to image the breasts. In this chapter, we present a method for validating finite element (FE) biomechanical models across the entire breast volume. A computational framework was used to generate personalised FE models of the breast to predict the deformations of the breasts under compression...

book

Computational Biomechanics for Medicine

Karol Miller, Poul M.F. Nielsen, Springer New York

Mathematical modelling and computer simulation have proved tremendously successful in engineering. One of the greatest challenges for mechanists is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, biomedical sciences, and medicine. The proposed workshop will provide an opportunity for computational biomechanics specialists to present...

article

Effects of fetal head shape variation on the second stage of labour

Xiani Yan, Jennifer A. Kruger, Poul M.F. Nielsen, Martyn P. Nash

Journal of Biomechanics > 2015 > 48 > 9 > 1593-1599

Fetal head geometry plays an important role in the mechanics of childbirth during the second stage labour. Large heads have been shown to be associated with difficult and prolonged childbirth. However, the relationship between the fetal head geometry and childbirth mechanics has not been quantitatively analysed. To address this, our study used finite element (FE) modelling techniques and biomechanical...

article

An automated hand‐held elastometer for quantifying the passive stiffness of the levator ani muscle in women

Jennifer A. Kruger, Poul M.F. Nielsen, Stephanie C. Budgett, Andrew J. Taberner

Neurourology and Urodynamics > 34 > 2 > 133 - 138

AimDesign and develop an automated, hand‐held instrument (elastometer) to assess in vivo passive stiffness of the pelvic floor muscle. Materials and MethodsThe elastometer system consisted of a hand piece, real‐time controller, and laptop computer. A cable connected the hand‐piece to the controller, which communicated with a laptop computer via an ethernet connection. Force sensitivity calibration...

article

Using Optical Coherence Tomography to Measure Dynamic Changes in the Geometry of Isolated Cardiac Trabeculae during a Twitch

Ming L. Cheuk, Alexander J. Anderson, June-Chiew Han, Bryan P. Ruddy, more

Biophysical Journal > 2015 > 108 > 2 Supplement 1 > 294a

article

Characterizing the ex vivo mechanical properties of synthetic polypropylene surgical mesh

Xinxin Li, Jennifer A. Kruger, Jessica W.Y. Jor, Vivien Wong, more

Journal of the Mechanical Behavior of Biomedical Materials > 2014 > 37 > Complete > 48-55

The use of synthetic polypropylene mesh for hernia surgical repair and the correction of female pelvic organ prolapse have been controversial due to increasing post-operative complications, including mesh erosion, chronic pain, infection, and support failure. These morbidities may be related to a mismatch of mechanical properties between soft tissues and the mesh. The aim of this study was to gain...

chapter

Optical coherence tomography imaging of cardiac trabeculae

Ming L. Cheuk, Norman Lippok, Alexander W. Dixon, Bryan P. Ruddy, more

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society > 182 - 185

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

An integrated instrument is being developed to study live cardiac trabeculae, which is capable of stimulating the muscle under controlled conditions while measuring the heat production, force, and sarcomere length distribution. To improve the accuracy of estimation of stress, strain, and volumetric heat production, the geometry of the muscle must be known. A spectral domain optical coherence tomography...

article

Examination of the Heat-Stress Relationship of Rat Cardiac Trabeculae using an Improved Muscle Calorimeter

Callum M. Johnston, June-Chiew Han, Bryan P. Ruddy, Poul M.F. Nielsen, more

Biophysical Journal > 2014 > 106 > 2 Supplement 1 > 773a

article

Breast lesion co-localisation between X-ray and MR images using finite element modelling

Angela W.C. Lee, Vijayaraghavan Rajagopal, Thiranja P. Babarenda Gamage, Anthony J. Doyle, more

Medical Image Analysis > 2013 > 17 > 8 > 1256-1264

This paper presents a novel X-ray and MR image registration technique based on individual-specific biomechanical finite element (FE) models of the breasts. Information from 3D magnetic resonance (MR) images was registered to X-ray mammographic images using non-linear FE models subject to contact mechanics constraints to simulate the large compressive deformations between the two imaging modalities...

article

Simulating the three-dimensional deformation of in vivo facial skin

Cormac Flynn, Andrew J. Taberner, Poul M.F. Nielsen, Sidney Fels

Journal of the Mechanical Behavior of Biomedical Materials > 2013 > 28 > Complete > 484-494

Characterising the mechanical properties of human facial skin is a challenging but important endeavour with applications in biomedicine, surgery simulation, forensics, and animation. Many existing computer models of the face are not based on in vivo facial skin deformation data but rather on experiments using in vitro facial skin or other soft tissues. The facial skin of five volunteers was subjected...

article

Creating Individual-specific Biomechanical Models of the Breast for Medical Image Analysis

Vijay Rajagopal, Angela Lee, Jae-Hoon Chung, Ruth Warren, more

Academic Radiology > 2008 > 15 > 11 > 1425-1436

Anatomically realistic biomechanical models of the breast potentially provide a reliable way of mapping tissue locations across medical images, such as mammograms, magnetic resonance imaging (MRI), and ultrasound. This work presents a new modeling framework that enables us to create biomechanical models of the breast that are customized to the individual. We demonstrate the framework's capabilities...

article

Frictional contact mechanics methods for soft materials: Application to tracking breast cancers

Jae-Hoon Chung, Vijay Rajagopal, Tod A. Laursen, Poul M.F. Nielsen, more

Journal of Biomechanics > 2008 > 41 > 1 > 69-77

Mammography is currently the most widely used screening and diagnostic tool for breast cancer. Because X-ray images are 2D projections of a 3D object, it is not trivial to localise features identified in mammogram pairs within the breast volume. Furthermore, mammograms represent highly deformed configurations of the breast under compression, thus the tumour localisation process relies on the clinician's...

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