Viscoelastic mechanical properties of the brain assessed with magnetic resonance elastography (MRE) are sensitive measures of microstructural tissue health in neurodegenerative conditions. Recent efforts have targeted measurements localized to specific neuroanatomical regions differentially affected in disease. In this work, we present a method for measuring the viscoelasticity in subcortical gray matter (SGM) structures, including the amygdala, hippocampus, caudate, putamen, pallidum, and thalamus. The method is based on incorporating high spatial resolution MRE imaging (1.6 mm isotropic voxels) with a mechanical inversion scheme designed to improve local measures in pre‐defined regions (soft prior regularization [SPR]). We find that in 21 healthy, young volunteers SGM structures differ from each other in viscoelasticity, quantified as the shear stiffness and damping ratio, but also differ from the global viscoelasticity of the cerebrum. Through repeated examinations on a single volunteer, we estimate the uncertainty to be between 3 and 7% for each SGM measure. Furthermore, we demonstrate that the use of specific methodological considerations—higher spatial resolution and SPR—both decrease uncertainty and increase sensitivity of the SGM measures. The proposed method allows for reliable MRE measures of SGM viscoelasticity for future studies of neurodegenerative conditions. Hum Brain Mapp 37:4221–4233, 2016. © 2016 Wiley Periodicals, Inc.

Objective: To develop a novel multi-TE MR spectroscopic imaging (MRSI) approach to enable label-free, simultaneous, high-resolution mapping of several molecules and their biophysical parameters in the brain. Methods: The proposed method uniquely integrated an augmented molecular-component-specific subspace model for multi-TE $^{1}$H-MRSI signals, an estimation-theoretic experiment optimization (nonuniform TE selection) for molecule separation and parameter estimation, a physics-driven subspace learning strategy for spatiospectral reconstruction and molecular quantification, and a new accelerated multi-TE MRSI acquisition for generating high-resolution data in clinically relevant times. Numerical studies, phantom and in vivo experiments were conducted to validate the optimized experiment design and demonstrate the imaging capability offered by the proposed method. Results: The proposed TE optimization improved estimation of metabolites, neurotransmitters and their $T_{2}$’s over conventional TE choices, e.g., reducing variances of neurotransmitter concentration by $\sim\! 40\%$ and metabolite $T_{2}$ by $\sim\! 60\%$. Simultaneous metabolite and neurotransmitter mapping of the brain can be achieved at a nominal resolution of 3.4 × 3.4 × 6.4 mm$^{3}$. High-resolution, 3D metabolite $T_{2}$ mapping was made possible for the first time. The translational potential of the proposed method was demonstrated by mapping biochemical abnormality in a post-traumatic epilepsy (PTE) patient. Conclusion: The feasibility for high-resolution mapping of metabolites/neurotransmitters and metabolite $T_{2}$’s within clinically relevant time was demonstrated. We expect our method to offer richer information for revealing and understanding metabolic alterations in neurological diseases. Significance: A novel multi-TE MRSI approach was presented that enhanced the technological capability of multi-parametric molecular imaging of the brain. The proposed method presents new technology development and application opportunities for providing richer molecular level information to uncover and comprehend metabolic changes relevant in various neurological applications.

BACKGROUND AND OBJECTIVES: Over a million sport-related concussions (SRC) affect children annually in the United States, posing a significant public health concern. Limited data exist on the premorbid risk factors and injury characteristics of SRCs in high school athletes. This study aims to understand acute SRC injury characteristics and describe premorbid risk factors in high school athletes. METHODS: Athletes (aged 14-19 years) from 19 central Illinois high schools participating in school-sponsored sports from 2009 to 2023 were included. Sports Concussion Assessment Tool evaluations were performed as part of preseason and postinjury evaluations. Injury characteristics, such as mechanism, setting, and symptoms, were described using all SRCs in the study period. Odds ratios (OR) were computed to determine risk factors using athletes with a baseline Sports Concussion Assessment Tool before SRC and nonconcussed athletes. RESULTS: In total, 4360 athletes were included (3953 without SRC; 407 with ≥1 SRC of whom 168 had a previous baseline). Overall, 24.2% of SRCs occurred in female athletes, and most SRCs occurred in competitions while playing American football (52.3%), soccer (20.4%), and basketball (7.6%). Blow/hit to the head was the most common mechanism. Headache was the most severe symptom (2.55 ± 1.51 [SD]), and symptoms of emotionality and nervousness/anxiety were significantly more severe in female athletes (P < .05). Students with previous concussions (OR 2.64 95% CI [1.81, 3.78]), previous hospitalization for head injury (OR 3.19 95% CI [1.9, 5.14]), headache/migraine disorders (OR 2.23 95% CI [1.29, 3.66]), and learning disabilities (OR 2.69 95% CI [1.47, 4.61]) had greater odds of SRC (P < .05). Lower odds of SRC were seen in athletes identifying as Black or African American (vs White) (OR 0.54 95% CI [0.32, 0.86]) and those attending larger (vs smaller) schools (OR 0.64 95% CI [0.46, 0.88]). CONCLUSION: Understanding SRC risk factors and characteristics in high school athletes is critical for developing prevention and management programs, guiding neurosurgeons in mitigating SRC risk, and informing return-to-play decisions.