Contrast-Enhanced Computed Tomography for Structural and Functional Evaluation of Ligament Microdamage

Detecting microstructural damage in ligaments remains a challenging case when no visible tearing occurs. This study introduces a novel application of micro-CT for ligament evaluation in wet tissue state with potential for clinical translation. We utilize neutral iodixanol and cationic tantalum oxide nanoparticles (Ta₂O₅-cNPs) for quantitative and qualitative imaging of microdamaged bovine ligaments. We hypothesize that neutral iodixanol reflects the ligament's functional alterations, while Ta₂O₅-cNPs will depict ligament structure by highlighting biphasic differences between the interfascicular matrix and fascicular regions. To examine these hypotheses, bovine anterior (N = 6) and posterior (N = 5) cruciate ligaments were assigned to control and damaged groups. All samples underwent biomechanical tensile testing to quantify the functional properties. Ligaments in the damaged group were strained up to 16% to create microdamage. Young's modulus was significantly reduced by 68% in the damaged group relative to the healthy group (p < 0.001). Samples were then separately immersed in each contrast agent and imaged using micro-CT at several timepoints during diffusion. The neutral iodixanol diffused faster compared to Ta₂O₅-cNPs, while Ta₂O₅-cNPs achieved approximately three times higher maximum partition. Although statistically significant differences in contrast agent partition between control and damaged groups were not observed, the findings demonstrate that (1) P_max of neutral iodixanol showed correlation with biomechanical properties specifically phase shift at frequencies of 0.1, 0.5, and 2 Hz indicating sensitivity to viscoelastic changes of the tissues, and (2) Ta₂O₅-cNPs enable visualization of the ligament's structures, supporting their potential for three-dimensional histological assessment.