Several in vivo quantitative magnetic resonance imaging (qMRI) techniques have been proposed as surrogate measures to map iron content in the human brain. The majority of in vivo qMRI iron mapping methods utilized the age-dependent iron content data based on postmortem data. In this work we fused atlas-based human brain volumetry obtained on a large cohort of healthy adults using FreeSurfer with T2 relaxation time measurements. We provide a brain atlas-based T2 relaxation time map which was subsequently used along with published postmortem iron content data to obtain a map of iron content in subcortical and cortical gray matter. We have also investigated the sensitivity of the linear model relating transverse relaxation rate with published iron content to the number of regions used. Our work highlights the challenges encountered upon using the simple model along with postmortem data to infer iron content in several brain regions where postmortem iron data are scant (e.g. corpus callosum, amygdale).

In this work we provide an up-to-date short review of computational magnetic resonance imaging (MRI) and software tools that are widely used to process and analyze diffusion-weighted MRI data. A review of different methods used to acquire, model and analyze diffusion-weighted imaging data (DWI) is first provided with focus on diffusion tensor imaging (DTI). The major preprocessing, processing and post-processing procedures applied to DTI data are discussed. A list of freely available software packages to analyze diffusion MRI data is also provided.

This work investigated the feasibility and utility of using T2-weighted or dual spin-echo data to provide volume and T2 relaxation time for regional and global gray and white matter using standardized brain templates and anatomically labeled atlases. A total of 130 healthy males and females (age range 15-59 years) were included. Dual echo magnetic resonance imaging data were acquired and analyzed using standardized International Consortium for Human Brain Mapping atlasbased tissue segmentation procedures implemented in the statistical parametric mapping toolbox to obtain the age trajectories of volume and corresponding T2 relaxation time in whole brain white and gray matter, in the caudate nucleus and in the anterior limb of internal capsule. Whole brain gray matter and caudate nucleus volumes linearly decreased with age while whole brain white matter and anterior limb internal capsule volume increased slowly with age bilaterally in males and females. The relation between T2 relaxation time and age of whole brain gray and white matter, and caudate nucleus and anterior limb internal capsule followed a quadratic Ucurve. The T2 relaxation times of the human brain followed a U curve both globally and regionally in both white and gray matter. Magn Reson Med 64:1382-1389,

The human brain thalami play essential roles in integrating cognitive, sensory and motor functions. In multiple sclerosis (MS), quantitative magnetic resonance imaging (qMRI) measurements of the thalami provide important biomarkers of disease progression, but late development and aging confound the interpretation of data collected from patients over a wide age range. Thalamic tissue volume loss due to natural aging and its interplay with lesion-driven pathology has not been investigated previously. In this work, we used standardized thalamic volumetry combined with diffusion tensor imaging (DTI), T2 relaxometry and lesion mapping on large cohorts of controls (N = 255, age range = 6.2- 69.1 years) and MS patients (N=109, age range = 20.8–68.5 years) to demonstrate early age- and lesion-independent thalamic neurodegeneration.

Noninvasive quantitative magnetic resonance imaging methods such as diffusion tensor imaging (DTI), can offer insights into structure/function relationships in human developmental brain disorders. In this report, we quantified macrostructural and microstructural attributes of the corpus callosum (CC) in children with dyslexia and typically developing readers of comparable age and gender. Diffusion anisotropy, mean, radial and axial diffusivities of cross-sectional CC sub-regions were computed using a validated DTI methodology. The normalized posterior CC area was enlarged in children with dyslexia compared to typically developing children. Moreover, the callosal microstructural attributes, such as mean diffusivity of the posterior middle sector of the CC, significantly correlated with measures of word reading and reading comprehension. Reading group differences in FA, MD, and RD were observed in the posterior CC (CC5). This study demonstrates the utility of regional DTI measurements of the CC in understanding the neurobiology of reading disorders.