Time-dependent diffusion tensor imaging and diffusion modeling of age-related differences in the medial gastrocnemius and feasibility study of correlations to histopathology.

PURPOSE: Implement STEAM-DTI to model time-dependent diffusion eigenvalues using the random permeable barrier model (RPBM) to study age-related differences in the medial gastrocnemius (MG) muscle. Validate diffusion model-extracted fiber diameter for histological assessment. METHODS: Diffusion imaging at different diffusion times (Δ) was performed on seven young and six senior participants. Time-dependent diffusion eigenvalues (λ2 (t), λ3 (t), and D⊥ (t); average of λ2 (t) and λ3 (t)) were fit to the RPBM to extract tissue microstructure parameters. Biopsy of the MG tissue for histological assessment was performed on a subset of participants (four young, six senior). RESULTS: λ3 (t) was significantly higher in the senior cohort for the range of diffusion times. RPBM fits to λ2 (t) yielded fiber diameters in agreement to those from histology for both cohorts. The senior cohort had lower values of volume fraction of membranes, ζ, in fits to λ2 (t), λ3 (t), and D⊥ (t) (significant for fit to λ3 (t)). Fits of fiber diameter from RPBM to that from histology had the highest correlation for the fit to λ2 (t). CONCLUSION: The age-related patterns in λ2 (t) and λ3 (t) could tentatively be explained from RPBM fits; these patterns may potentially arise from a decrease in fiber asymmetry and an increase in permeability with age.

Achieving Equity in Asian American Healthcare: Critical Issues and Solutions.

Equity is a fundamental goal of the US health care system. Asians comprise 6% of the US population, and 60% of the world's population. Less than 1% of National Institutes of Health funding is directed toward Asian health. Asian health outcomes are often worse than non-Hispanic Whites (NHWS) in America. Increasing federal and foundation resources and funding toward Asian health research could illuminate these risks and develop precision interventions to reduce known health disparities. When disaggregated by race/ethnicity, Asian health risks are even more apparent. Here, we discuss critical health outcome differences between the six major Asian American subgroups (Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese) comprising 80% of the US Asian population, highlighting demographic, pharmacologic, disease prevalence, and mortality outcomes. We then outline seven critical issues contributing to Asian American health disparities, including aggregated Asian health data, undersampling, invalid extrapolations, underrepresentation in clinical trials, lack of funding and awareness of disparities, and the model minority myth. Building on the successes of national public health initiatives, we propose nine leverage points to improve Asian American health including the following: obtaining disaggregated Asian health data, improved Asian health research (oversampling Asians, improving clinical trial participation, and increasing research funding), stakeholder collaboration (national and with Asian nations), community engagement, providing culturally precise health care, and expansion of the Asian American research ecosystem. Achieving health equity takes deliberate practice and does not occur by accident. By addressing critical issues that perpetuate Asian health disparities, we grow closer to understanding how to effectively improve Asian health and build a nationally unified mindset toward action that emphasizes equitable care for all.