Quantitative Morphometric Analysis of Human Myocardial Trabeculae Across Ethnic Groups

Thesis Abstract

This study addresses the underexplored variability in human myocardial trabeculae morphology across ethnic groups and its potential implications for cardiac function and disease assessment. The problem centers on whether normative trabecular morphometry—characterized by trabecular thickness, spacing, density, and fractal dimension—differs systematically among populations, potentially confounding diagnostic imaging interpretations and risk stratification in cardiomyopathy. The aim is to quantify intercultural differences in myocardial trabecular architecture and to evaluate their associations with key demographic and physiological covariates. Specific objectives are (1) to establish robust morphometric baselines for trabecular thickness, intertrabecular spacing, trabecular density, and fractal dimension across four ethnic cohorts (Caucasian, African, East Asian, and Hispanic); (2) to examine sex, age, body size, and resting hemodynamics as covariates of trabecular morphometry; (3) to test whether observed morphometric differences persist after controlling for cardiac chamber size and overall left ventricular mass; (4) to explore correlations between trabecular metrics and indices of left ventricular function such as ejection fraction and myocardial strain; and (5) to integrate findings within a theoretical framework incorporating allometric scaling and morphometric invariants. Methodologically, a cross-sectional, observational design will be employed. The population consists of healthy adults aged 25–60 years, stratified into four ethnic groups with equal representation (n = 80 per group, total N = 320). Cardiac magnetic resonance imaging (MRI) will be used to acquire high-resolution cine images and late gadolinium enhancement sequences. Data collection instruments include standardized MRI protocols for 3D reconstruction of the left ventricle and automated segmentation software to extract trabecular metrics mean trabecular thickness, mean intertrabecular spacing, trabecular density (surface-to-volume ratio), and fractal dimension of trabecular networks. Demographic data, anthropometrics, resting blood pressure, and heart rate will be recorded. To ensure measurement validity, intra- and inter-observer reliability will be assessed on 10% of the sample, using intraclass correlation coefficients and Bland-Altman analysis. The analytic framework integrates both descriptive statistics and multivariate modeling. Descriptive analyses will compare morphometric parameters across ethnic groups using ANOVA with post hoc pairwise comparisons, adjusting for sex and age. Multivariate linear regression will assess predictors of trabecular metrics, including ethnicity, body surface area, LV mass, and hemodynamic indices. A hierarchical linear modeling approach will be considered to account for potential clustering by imaging center. To explore non-linear relationships, generalized additive models (GAMs) will be used where appropriate. The research will be framed by two theoretical lenses allometric scaling theory, which posits systematic changes in tissue architecture with body size, and morphological invariants theory, which suggests conserved fractal properties across populations despite size differences. The expected findings include statistically significant interethnic differences in trabecular morphology after controlling for confounders, with African and East Asian cohorts showing distinct fractal dimensions and density patterns relative to Caucasian peers. It is anticipated that sex and age will modestly modulate trabecular metrics, while LV mass and chamber size will partially mediate observed ethnic distinctions. The study aims to contribute to knowledge by establishing normative, ethnicity-informed baselines for trabecular morphometry, informing population-specific interpretation of cardiac MRI metrics, and highlighting potential considerations for risk assessment in cardiomyopathies where trabecular architecture may influence functional measurements. The study's contribution to knowledge includes providing a standardized protocol for quantitative trabecular morphometry in vivo, demonstrating the necessity of accounting for ethnic variation in cardiac imaging biomarkers, and offering empirical data to refine allometric and fractal-based models of myocardial microstructure. The main conclusion is that ethnicity exerts measurable effects on myocardial trabecular architecture that persist after adjustment for body size and LV mass, underscoring the need for ethnicity-aware normative databases in cardiac imaging. Recommendations include the development of population-specific reference ranges for trabecular metrics, incorporation of trabecular morphometry into comprehensive cardiac risk models, and further longitudinal research to assess how these morphometric differences relate to incident cardiomyopathic phenotypes and functional outcomes.