Contrast agent-enhanced micro-CT of the healthy and injured spinal cord

Traumatic spinal cord injury is a life changing condition, and treatment options are still limited. While a great deal of work has been done in the last decade to improve the understanding of tissue degeneration and repair, more work is necessary to translate this knowledge into the clinic to improve the outcome for patients. Imaging modalities for the spinal cord play an important role in this process but are currently mostly limited to destructive two-dimensional histology and expensive, low-resolution 3D MRI. This work seeks to expand the existing ex vivo imaging possibilities in preclinical research with a cost-effective, non-destructive technique for both healthy and injured spinal cords.We imaged 13 spinal cords using Lugol’s iodine, Hf-POM and Accupaque as contrast enhancing staining agents (CESAs) for µCT imaging. These included: uninjured spinal cords of 8 rats, 4 rat spinal cords with a contusion injury as well as one healthy spinal cord from a human body donor. CECT acquisitions were performed with an array of different settings at resolutions between 1.2 µm for detailed structural evaluation and 18 µm for contusion injury quantification. We further performed comparative classical histological analysis on 5 rat spinal cords and the human spinal cord for validation purposes.For the first time, .we obtained high resolution structural information of the healthy spinal cord using CESAs Lugol’s iodine and Hf-POM, with clear distinction of white and gray matter, visualization of numerous neuronal tracts and fiber bundles. We could detect individual cells such as motoneurons, down to the small fibers of the intramedullary bundles, which run from motoneurons to the ventral rootlets. We could further demonstrate compatibility of immunohistology post-processing with CECT. In the injured spinal cord, both Lugol’s iodine and Accupaque staining provide useful information regarding the extent and composition of the lesioned area.We demonstrate that CECT imaging provides unprecedented 3D structural detail in a non-destructive manner. Though limited to ex-vivo applications, this method provides resolutions that far exceed those achievable with current MRI technology. We provide examples of staining procedures for a range of applications of the spinal cord. We believe the techniques described here are especially useful in combination with classical histological examination and provide additional details in a cost-effective manner.