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A Cross-Sectional, Multi-Site Study of T1 Weighted Magnetic Resonance Image Properties

Greer, Phil (2013) A Cross-Sectional, Multi-Site Study of T1 Weighted Magnetic Resonance Image Properties. Master's Thesis, University of Pittsburgh. (Unpublished)

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Cross sectional Magnetic Resonance Imaging (MRI) studies of the human brain have shown age related changes in morphometric measures as well as signal properties like tissue contrast. Greater access to open data sets and an emphasis on multicenter studies make repeatability of measures important. This study takes a novel dataset and MRI from the IXI open dataset to examine age related changes in MRI signal properties across sites.
We processed T1 weighted MRIs of 1131 subjects from 3 sites using established tissue segmentation tools and region of interest sampling techniques to get regional and global estimates of signal intensity and volume. Signal intensity estimates were used to calculate gray-white contrast values. We created multiple linear regression models of the age related changes in gray-white contrast, within tissue coefficient of variation (CV), and tissue volume while controlling for the effects of gender and site. In addition we compared the contrast results computed using our method to the recent methods provided with FreeSurfer.
Signal intensity decreased with age in two sites while increasing with age in the third. Gray-white contrast showed a decline with age in most regions across all sites. CV increased with age across all regions, sites and tissue types. GM and WM volume decreases with age globally and regionally while CSF volume increased with age. The three methods show strong proportional bias and poor agreement.
It is problematic to make inferences about MRI signal intensity without first normalizing the result. Measures of contrast and CV are both normalized views of signal intensity and both show similar if inverse relationships with age. Volume changes seen here are in agreement with previously published results, but the rates differ by site. Normalizing volume measurements by inter-cranial volume removes the site-specific rate differences. While the gray-white contrast calculation methods show strong correlation, the estimates are not comparable.
Age related MRI signal property changes exist and may affect morphometric measurements. The public health relevance of this research relates to the possibility that MRI contrast may be a biomarker for use in diagnosing neurodegenerative diseases like Alzheimer’s that affect elderly populations allowing earlier detection and treatment.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Greer, Philpgreer@pitt.eduPGREER
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairMazumdar, Satimaz1@pitt.eduMAZ1
Committee MemberBecker, James T.beckerjt@upmc.eduBECKERJT
Committee MemberYouk, Adayouk@pitt.eduYOUK
Date: 27 June 2013
Date Type: Publication
Defense Date: 28 January 2013
Approval Date: 27 June 2013
Submission Date: 29 March 2013
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 70
Institution: University of Pittsburgh
Schools and Programs: School of Public Health > Biostatistics
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: magnetic resonancing imaging, aging, cerebral cortex, tissue contrast, gray matter
Date Deposited: 27 Jun 2013 18:11
Last Modified: 01 May 2018 05:15

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  • A Cross-Sectional, Multi-Site Study of T1 Weighted Magnetic Resonance Image Properties. (deposited 27 Jun 2013 18:11) [Currently Displayed]


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