Abstract Body: Background: Males and smokers are established risk factors for abdominal aortic (AA) disease, yet detailed assessment of aortic wall morphology and calcification is constrained by the resolution of clinical imaging. Clinical CT lacks spatial sensitivity to quantify wall thickness, lumen geometry, or spatial calcium distribution. In contrast, non-clinical micro-computed tomography (micro-CT) enables direct 3D evaluation of aortic microanatomy. We used micro-CT to quantify AA lumen geometry and calcification burden by sex and smoking status.

Methods: Cadaveric abdominal aortas (n=26; mean age 79.3 ± 9.8 years) were scanned using micro-CT at 20-25 μm resolution (0.02-0.025 mm slice thickness). Calcified volume was quantified by threshold-based segmentation and normalized to vessel length (calcium burden, mm) in Dragonfly software by Object Research Systems. Each vessel was divided into 10 evenly spaced cross-sections to measure lumen area and maximum wall thickness, from which vessel-level means and coefficients of variability (CV) were calculated. Comparisons were performed using Mann-Whitney U (for non-parametric, continuous data) and t-tests (for parametric), and chi-square tests for categorial variables.

Results: Baseline characteristics were similar across sex and smoking strata. Females demonstrated significantly greater normalized calcification burden than males (median 27.3 vs. 2.35 mm, p = 0.010) despite smaller mean lumen area (101 ± 33.8 vs. 152 ± 48.8 mm², p = 0.011). Maximum wall thickness and morphometric heterogeneity did not differ by sex. No significant differences in calcification burden, wall thickness, lumen area, or heterogeneity were observed between smokers and non-smokers. Stratification by cumulative risk factors (female non-smokers [0], either male or smoker [1], both [2]) showed nonsignificant trends toward lower calcification burden and larger lumen area in individuals with both risk factors (p = 0.072).

Conclusions: High-resolution non-clinical micro-CT reveals exploratory sex and exposure-related patterns in abdominal aortic morphology that diverge from established epidemiologic risk models. Microstructural calcification patterning may influence local wall stiffness and stress distribution, providing a potential mechanistic link to sex differences observed in abdominal aortic disease progression. These findings highlight the value of micro-CT for detailed vascular phenotyping and support further mechanistic studies.