Abstract Body: Background: Calcium morphology influences vascular biomechanics, plaque stability, and outcomes of coronary interventions. Clinical CT is routinely used to quantify overall calcium burden but lacks the spatial resolution to accurately characterize distinct morphological subtypes such as concentric, eccentric, and nodular calcification. To overcome challenges with resolution, we used non-clinical micro-computed tomography (micro-CT) to quantitatively compare coronary calcium morphologies in cadaveric left anterior descending arteries (LADs).

Methods: Cadaveric LADs (n=15, mean age 84.6 ± 9.7, 60% male) were scanned using micro-CT. Imaging parameters include 60 kV X-ray voltage, 133 µA current, 1150 ms exposure, and 0.2° steps over 360° rotation. Lesions were defined as continuous calcium not separated by >2mm of non-calcified lumen. Within each lesion, cross-sectional slices (n=129) were analyzed at 2mm intervals and classified as concentric (≥180° arc), eccentric (<180° arc), or nodular (protruding). Quantitative parameters were measured, including maximum calcium thickness, area, arc, and lumen area. Vessel-level (age, sex, cause of death, lesion count) and slice-level parameters were compared among morphology classes. Morphology categories were not mutually exclusive at the vessel level.

Results: At the vessel level, age, sex, cause of death, and lesion count did not significantly differ across calcium morphology classes (all p > 0.05). At the slice level, concentric calcium demonstrated significantly greater calcium area (median 5.71 [IQR 5.06, 7.74] mm²) compared with eccentric (1.52 [0.57, 2.89] mm²) and nodular calcium (1.98 [0.66, 3.00] mm²; p = 0.002). Lumen area was smallest in concentric sections (2.82 [2.13, 4.50] mm²) compared with eccentric sections (5.05 [3.04, 7.03] mm²; p = 0.020). Calcium thickness did not differ significantly across morphologies.

Conclusions: Non-clinical micro-CT enables high-resolution, slice-level quantification of coronary calcium morphology. Morphology distribution was independent of age and sex, suggesting it reflects local vessel biomechanics rather than systemic factors. Concentric calcium showed the greatest area with smaller luminal area, potentially suggesting greater luminal compromise and potentially greater ischemic burden.