Lyam Hollis

• Phyics, Astrophysics and Cosmology MPhys
• University of Edinburgh

Inflammation detected through the uptake of ultrasmall superparamagnetic particles of iron oxide (USPIO) on magnetic resonance imaging (MRI) and finite element (FE) modelling of tissue stress both hold potential in the assessment of abdominal aortic aneurysm (AAA) rupture risk. This study aimed to examine the spatial relationship between these two...

Purpose: To develop finite element analysis (FEA) of magnetic resonance elastography (MRE) in the human thigh and investigate inter-individual variability of measurement of muscle mechanical properties. Methods: Segmentation was performed on MRI datasets of the human thigh from 5 individuals and FEA models consisting of 12 muscles and surroundin...

Introduction . Patient specific modelling (PSM) of abdominal aortic aneurysm (AAA) aims to predict rupture risk by calculating the peak stress acting on the AAA wall using finite element analysis (FEA). It is hypothesised that magnetic resonance elastography (MRE), a non-invasive technique measuring material properties, can improve PSM by allowing...

Methods: A new MRE image processing pipeline was developed that incorporates wavelet-domain denoising, image-driven noise estimation, and feature detection. ESP was first validated using simulated data, including viscoelastic Finite Element Method (FEM) simulations, at multiple noise levels. ESP images were compared with MDEV pipeline images, both...

Magnetic resonance elastography (MRE) utilises an inversion algorithm to create maps of material properties (elastograms) from displacements caused by mechanically induced shear waves. This study aimed to assess the accuracy of measurements from multi-dual elasto-visco (MDEV) inversion in comparison to direct inversion (DI) in simplistic geometries...

The clinical diagnosis of atherosclerosis via the measurement of stenosis size is widely acknowledged as an imperfect criterion. The vulnerability of an atherosclerotic plaque to rupture is associated with its mechanical properties. The potential to image these mechanical properties using magnetic resonance elastography (MRE) was investigated throu...

Introduction Magnetic resonance elastography (MRE) utilizes mechanically induced shear waves to attain material property measurements of in vivo tissue. Finite element analysis (FEA) can be used to replicate the technique in silico to aid in the testing and development of the MRE post-processing software. This study aimed to investigate the influen...

It is widely acknowledged that assessing the rupture risk of atherosclerotic plaques, via lumen reduction, is an imperfect criterion and that other properties such as those related to biomechanics may be more relevant. This study investigated the hypothesis that magnetic resonance elastography (MRE) can be used to image the elasticity of atheroscle...

Oxygenation defects may contribute to renal disease progression but the chronology of events is difficult to define in vivo without recourse to invasive methodologies. BOLD MRI provides an attractive alternative but the R2* signal is physiologically complex. Post-acquisition data analysis often relies on manual selection of region(s) of interest. T...

Oxygenation defects may contribute to renal disease progression but are difficult to define in vivo without invasive methods. BOLD MRI provides a non‐invasive alternative but the signal is physiologically complex and data analysis often rely on region of interest selection, excluding biological information. We present an analysis pipeline that comp...

Introduction Ultrasound has been applied to measure vessel diameter and blood flow velocity to compute the wall shear rate (WSR) in arteries. This paper describes a fast technique to assess the WSR waveform using an image of a pulsed Doppler waveform downloaded from a modern clinical ultrasound scanner. Methods A walled vascular phantom has been d...

Withdrawal Notice DOI: 10.1177/1742271X1302100105 Xin Yang, Lyam Hollis, Fiona Adams, Faisel Khan, Peter R Hoskins. A Fast Method to Estimate the Wall Shear Stress Waveform in Arteries. Ultrasound. 2013; 21(1): 23–28. Article withdrawn by publisher. This article was accidentally published twice in the online version of Volume 21 Issue 1, with diffe...