A longitudinal structural MRI study of change in regional contrast in Autism Spectrum Disorder

Authors: Avantika Vardhan1, Joseph Piven2, Marcel Prastawa3, Guido Gerig3 Institutions: 1Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, United States, 2Dept of Psychiatry, UNC School of Medicine, Chapel Hill, NC, 3University of Utah, Salt Lake City, UT Introduction: The brain undergoes tremendous changes in shape, size, structure, and chemical composition, between birth and 2 years of age [Rutherford, 2001]. Existing studies have focused on morphometric and volumetric changes to study the early developing brain. Although there have been some recent appearance studies based on intensity changes [Serag et al., 2011], these are highly dependent on the quality of normalization. The study we present here uses the changes in contrast between gray and white matter tissue intensities in structural MRI of the brain, as a measure of regional growth [Vardhan et al., 2011]. Kernel regression was used to generate continuous curves characterizing the changes in contrast with time. A statistical analysis was then performed on these curves, comparing two population groups : (i) HR+ : high-risk subjects who tested positive for Autism Spectrum Disorder (ASD), and (ii) HR- : high-risk subjects who tested negative for ASD.