Kin Quan - Zenglei Zhou - CMIC-WEISS joint seminar series

Kin Quan - Title: Modelling Airway Geometry as Stock Market Data using Bayesian Changepoint Detection

Abstract: Numerous lung diseases, such as idiopathic pulmonary fibrosis (IPF), exhibit dilation of the airways. Accurate measurement of dilatation enables assessment of the progression of disease. Unfortunately the combination of image noise and airway bifurcations causes high variability in the profiles of cross-sectional areas, rendering the identification of affected regions very difficult. Here we introduce a noise-robust method for automatically detecting the location of progressive airway dilatation given two profiles of the same airway acquired at different time points. We propose a probabilistic model of abrupt relative variations between profiles and perform inference via Reversible Jump Markov Chain Monte Carlo sampling. We demonstrate the efficacy of the proposed method on two datasets; (i) images of healthy airways with simulated dilatation; (ii) pairs of real images of IPF-affected airways acquired at 1 year intervals. Our model is able to detect the starting location of airway dilatation with an accuracy of 2.5mm on simulated data. The experiments on the IPF dataset display reasonable agreement with radiologists. We can compute a relative change in airway volume that may be useful for quantifying IPF disease progression. (https://arxiv.org/abs/1906.12225)

Fenglei Zhou - Co-electrohydrodynamic forming of biomimetic phantoms for diffusion magnetic resonance imaging

Abstract

My research has been primarily focused on co-electrohydrodynamic (co-EHD) forming of biomimetic hollow polymeric microfibres and microspheres for application in diffusion MRI. Co-EHD produces multilayer fibres and spheres with sizes ranging from tens of nms to tens of µms using an electric field between a coaxial spinneret and a grounded collector. The electrical shear stress elongates the core and the shell liquid menisci at the spinneret outlet to form an inverted triangle shape called a ‘Taylor cone’. At the end of the Taylor cone, the jet of liquid extends from millimetres to centimetres and is stretched into core-shell structured filaments (in the case of electrospinning) or broken into core-shell structured particles (in this case of electrospraying) owing to electrohydrodynamic forces.

Co-EHD hollow polymeric microfibres and microspheres have been used for the first time as building blocks to design and construct brain, heart and tumour cell-mimicking phantoms for the validation of diffusion MRI measurement. These image phantoms have demonstrated excellent performance, in terms of MR sensitivity to fibres/sphere microstructure and size, the reproducibility and the stability of MR measurement in both longitudinal and multi-centre studies.