Investigation of age dependent contrast and T1 differences in MR images at 3.0 T: a study on MPRAGE, SPIN ECHO and FLASH protocols

Aktaş, Hayriye
During healthy aging, the brain undergoes several structural changes such as brain atrophy, decreased volume of GM and WM and increase in CSF volume. These changes introduce prominent low contrast effects to the MRI images of the aging population, causing segmentation problems in the data processing pipeline. Measures of tissue characteristics such as T1, T2 provide unique and complementary information to widely used measures of brain atrophy. In this study, image quality metrics such as contrast, SNR, CNR and GWR devised from 3 cortical and 2 sub-cortical regions of interest are used to evaluate the efficiency of MPRAGE and spin echo (SE) scans across ages. Multiple FLASH images are collected with varying flip angles for estimation of T1 within the GM areas in order to guarantee optimal TR values before the acquisition of SE images. While investigating the results of our parameter selection by calculations on MPRAGE and SE scans, we also utilized whole brain T1 images computed from multi-contrast FLASH images. As a result, we found that in terms of contrast and gray-white ratios (GWR), T1 estimated whole brain images are superior to MPRAGE and SE protocols, especially within sub-cortical areas. Furthermore, in T1 estimated whole brain images, degradation of contrast and GWR due to aging processes is observed to be less pronounced. In our comprehensive evaluation of MPRAGE, SE and FLASH images in young and aged healthy subjects, we observed that T1 estimations derived from FLASH images are useful for improving contrast and GWR.


Functional magnetic resonance imaging (fMRI) simulator
Arslankoz, Kamil; Gökçay, Didem; Department of Medical Informatics (2015)
Functional magnetic resonance imaging (fMRI) utilizes the change in the oxygenation of blood to predict active areas in the brain. fMRI consists of multiple low resolution whole brain images, for which, the contrast difference in corresponding voxels among all images are studied. In this study, an fMRI simulator has been developed which generates customized 4D fMRI data that can be used as a ground truth for comparing/benchmarking different fMRI analysis methods. This simulator can be also used for educatio...
Aktaş Dinçer, Hayriye; Gökçay, Didem (2014-04-25)
During healthy aging, the brain undergoes several structural changes which introduce prominent low contrast on the MR images. In this study, the low contrast effects causing segmentation problems were analyzed in the context of image quality ratios such as signal to noise, contrast to noise and gray white intensity: SNR, CNR, GWR. The evaluation of the T-1-weighted MPRAGE and SE scans was conducted across ages. Also by collecting multiple FLASH images with varying flip angles for estimation of T-1, the diff...
Evaluation of neointimal hyperplasia on tranilast-coated synthetic vascular grafts: An experimental study
Karakayali, Feza; Haberal, Nihan; Tufan, Hale; Hasırcı, Nesrin; BaSaran, Ozgur; Sevmis, Sinasi; Akdur, Aydin; Kızıltay, Aysel; Haberal, Mehmet (2007-01-01)
Tranilast is an antiallergic drug that interferes with proliferation and migration of vascular smooth muscle cell induced by platelet-derived growth factor (PDGF) and transforming growth factor-beta 1 (TGF-beta 1). We investigated the local effect of tranilast on neointimal hyperplasia using tranilastcoated prosthetic grafts. The inner sides of the thin-walled polytetrafluoroethylene (PTFE) grafts were coated with chitosan and tranilast containing chitosan solution. Wistar albino rats (32) were used in the ...
Transcriptomic network analysis of brain aging and alzheimers disease
Parvizi, Poorya; Somel, Mehmet; Tunçbağ, Nurcan; Department of Biology (2017)
Multiple studies have investigated aging brain transcriptomes to identify for age-dependent expression changes and determine genes that may participate in age-related dysfunction. However, aging is a highly complex and heterogeneous process where multiple genes contribute at different levels depending on individuals’ environments and genotypes. Both this biological heterogeneity of aging, as well as technical biases and weaknesses inherent to transcriptome measurements, limit the information gained from a s...
Temporal changes in the gene expression heterogeneity during brain development and aging
Isildak, Ulas; Somel, Mehmet; Thornton, Janet M.; Donertas, Handan Melike (Springer Science and Business Media LLC, 2020-03-01)
Cells in largely non-mitotic tissues such as the brain are prone to stochastic (epi-)genetic alterations that may cause increased variability between cells and individuals over time. Although increased interindividual heterogeneity in gene expression was previously reported, whether this process starts during development or if it is restricted to the aging period has not yet been studied. The regulatory dynamics and functional significance of putative aging-related heterogeneity are also unknown. Here we ad...
Citation Formats
H. Aktaş, “Investigation of age dependent contrast and T1 differences in MR images at 3.0 T: a study on MPRAGE, SPIN ECHO and FLASH protocols,” M.S. - Master of Science, Middle East Technical University, 2013.