An Investigation of Signal Characteristics and T_1 Relaxation Time in Brain MR Images of Young versus Old Healthy Adults

摘要

During healthy aging, the brain undergoes several structural changes such as atrophy and volumetric changes. Although less evident, changes in tissue concentration also occur. Such differences in brain tissues 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 T_1 provide unique and complementary information to widely used measures of brain signal characteristics. In this study, multiple Fast Low Angle Shot (FLASH) images are collected for T_1 mapping of whole brains from young and old adults. Tissue signal characteristics are evaluated on predefined regions and compared across Magnetization Prepared Rapid Gradient Echo (MPRAGE) and T_1 maps. Additionally, segmentation performance is analyzed. As a result, we found that T_1 maps are superior to MPRAGE protocol in terms of contrast, especially within sub-cortical areas. Furthermore, degradation of grey-white-ratio (GWR) due to aging processes is observed to be less pronounced in T_1 estimated whole brain images. Moreover, sensitivity of T_1 maps (54.6%) are higher than MPRAGE images (34.4%) in detection of sub-cortical gray matter. In sum we concur that T_1 maps provide better avenues to investigate age related morphological changes in the brain.