Micro-Computed Tomography analysis methods to assess sheep cancellous bone preservation

The goal of this study was to determine if mineral dissolution from cancellous bone specimens alters stereology parameters determined by Micro-Computed Tomography (Micro-CT). Sheep cancellous bone cores were excised from lumbar vertebrae and randomized for immediate storage in one of four ¿bathing¿ solutions - Phosphate Buffered Saline (PBS), PBS supersaturated with Hydroxyapatite (HA) (PBS+HA), PBS supplemented with Protease Inhibitor cocktail solution (PBS+PI), and Supersaturated HA PBS supplemented with Protease Inhibitor Cocktail (PBS+HA+PI). An additional sample was stored in 70% Ethanol (EtOH) to provide reference values since samples are often stored and processed by micro-CT in EtOH prior to mechanical tests. Common micro-CT parameters used to examine bone structure and quality can assess vertebral cancellous bone changes due to storage and handling. Micro-CT data were collected while the samples were stored in their storage and bathing solutions at baseline (t=0 months). Following data collection, samples were stored at -20°C for 6 months. Micro-CT data were re-collected and degradation effects on the cancellous bone specimens were evaluated in stereology parameters between samples stored in different solutions and for both time points. Specimen geometry and selected volumes used for data analysis were assessed for possible computational differences due to the software algorithms used for stereology. No differences were seen at baseline due to the specimen size or the pre-determined analysis volumes. Stereology differences were seen between bathing media groups at 6 months. Additionally, threshold values used for processing were different between the bathing solutions, reflecting changes due to solution density differences.