MULTI-RESOLUTION LC-MS IMAGE ALIGNMENT SCHEME

MPhil Thesis Defence


Title: "MULTI-RESOLUTION LC-MS IMAGE ALIGNMENT SCHEME"

By

Mr. Kai Ho WU


Abstract

Liquid chromatography-mass spectrometry (LC-MS) is a widely used technique 
in the field of proteomics for biomarker discovery and protein 
identification. An LC-MS experiment determines the components of a 
chemical mixture and the result can be represented as a two-dimensional 
image, where the LC retention time and the mass-to-charge ratio are the 
abscissa and the ordinate respectively, while the signal intensities 
indicate the abundance of detected chemicals. In many LC-MS based 
applications, it is often required to compare samples from different 
experiments, and thus multiple LC-MS images. Since there is always a 
non-linear LC retention time shifting across LC-MS images, alignment 
between images is needed prior to performing any analysis.

In this thesis, we introduce a multi-resolution LC-MS image alignment 
scheme for synchronizing LC-MS images. The multi-resolution scheme employs 
one of two popular time alignment algorithms, Dynamic Time Warping (DTW) 
or Correlation Optimized Warping (COW), as the optimization algorithm, 
while Kullback-Leibler Distance (KLD) is used as the local similarity 
measure. We have validated the proposed scheme using two real-world data 
sets, which include both high mass accuracy and low mass accuracy LC-MS 
images. In addition, we have also compared the results with an existing 
alignment algorithm, the Dynamic Time Warping-Component Detection 
Algorithm (DTW-CODA). The experiments show that the proposed scheme 
outperforms DTW-CODA, and is a promising approach for aligning both high 
mass accuracy and low mass accuracy LC-MS images.


Date:			Tuesday, 19 August 2014

Time:			2:00pm - 4:00pm

Venue:			Room 4483
 			Lifts 25/26

Committee Members:	Prof. Albert Chung (Supervisor)
 			Dr. Henry Lam (CBME) (Supervisor)
 			Prof. Dit-Yan Yeung (Chairperson)
 			Dr. Huamin Qu


**** ALL are Welcome ****