Quantification and spatiotemporal modeling of tissue appearance in MR (magnetic resonance) studies of brain development

Update item information
Publication Type dissertation
School or College College of Engineering
Department Bioengineering
Author Vardhan, Avantika
Title Quantification and spatiotemporal modeling of tissue appearance in MR (magnetic resonance) studies of brain development
Date 2016
Description Magnetic Resonance (MR) is a relatively risk-free and flexible imaging modality that is widely used for studying the brain. Biophysical and chemical properties of brain tissue are captured by intensity measurements in T1W (T1-Weighted) and T2W (T2-Weighted) MR scans. Rapid maturational processes taking place in the infant brain manifest as changes in co{\tiny }ntrast between white matter and gray matter tissue classes in these scans. However, studies based on MR image appearance face severe limitations due to the uncalibrated nature of MR intensity and its variability with respect to changing conditions of scan. In this work, we develop a method for studying the intensity variations between brain white matter and gray matter that are observed during infant brain development. This method is referred to by the acronym WIVID (White-gray Intensity Variation in Infant Development). WIVID is computed by measuring the Hellinger Distance of separation between intensity distributions of WM (White Matter) and GM (Gray Matter) tissue classes. The WIVID measure is shown to be relatively stable to interscan variations compared with raw signal intensity and does not require intensity normalization. In addition to quantification of tissue appearance changes using the WIVID measure, we test and implement a statistical framework for modeling temporal changes in this measure. WIVID contrast values are extracted from MR scans belonging to large-scale, longitudinal, infant brain imaging studies and modeled using the NLME (Nonlinear Mixed Effects) method. This framework generates a normative model of WIVID contrast changes with time, which captures brain appearance changes during neurodevelopment. Parameters from the estimated trajectories of WIVID contrast change are analyzed across brain lobes and image modalities. Parameters associated with the normative model of WIVID contrast change reflect established patterns of region-specific and modality-specific maturational sequences. We also detect differences in WIVID contrast change trajectories between distinct population groups. These groups are categorized based on sex and risk/diagnosis for ASD (Autism Spectrum Disorder). As a result of this work, the usage of the proposed WIVID contrast measure as a novel neuroimaging biomarker for characterizing tissue appearance is validated, and the clinical potential of the developed framework is demonstrated.
Type Text
Publisher University of Utah
Subject appearance; contrast; imaging; Infant brain; MR; neurodevelopment
Dissertation Name Doctor of Philosophy
Language eng
Rights Management ©Avantika Vardhan
Format Medium application/pdf
Format Extent 2,905,530 bytes
Identifier etd3/id/4301
ARK ark:/87278/s6p01h1r
Setname ir_etd
Date Created 2016-10-13
Date Modified 2021-05-06
ID 197846
Reference URL https://collections.lib.utah.edu/ark:/87278/s6p01h1r
Back to Search Results