C. Flynn (Guelph, CA)
Presenter Of 1 Presentation
23.2.10 - Apparent Density of osteoarthritic cartilage is influenced by integrity of the superficial zone in non-equilibrium contrast-enhanced CT
Abstract
Purpose
Investigate the feasibility of using non-equilibrium contrast-enhanced computerized tomography (CE-CT) to address the problem of staging cartilage injury and osteoarthritis (OA) in species with thin cartilage.
Methods and Materials
A pilot study was performed on n=39 bovine osteochondral blocks with three types of superficial cartilage damage: intact, fibrillated and delaminated. Samples were exposed to 60% CystoConray or lactated ringer’s (LRS) solution for 10 minutes, then imaged at a resolution of 45 microns. In the in-vivo study OA was induced by arthroscopic meniscal destabilization (MMT) in n=20 adult female sheep plus n=4 as naive controls. One intra-articular injection of anionic media was given 13 weeks post-MMT and CT images of both stifles joints were obtained 10 minutes after injection. Sheep were sacrificed at two time points: 3 months post-MMT (early OA (n=9)), or 12 months (late OA n = 11) and the normal controls. Stifles were dissected and the proximal tibia was immersed in contrast media for 10 minutes prior to micro CT. Cartilage samples were harvested for a proteoglycan biochemical assay along with osteochondral sections for histology.
Results
Removal of the superficial cartilage zone resulted in elevated apparent density of bovine cartilage compared to intact controls (p<0.01). Cartilage visibility in the stifle of anesthetized sheep was also significantly improved during CT imaging by the contrast after a 10 minute delay (p<0.05) compared to the non-contrast enhanced contralateral stifle. Apparent density in ex vivo cartilage correlated negatively (r = -0.56) with sGAG in the medial tibial plateau (R2 = 0.28, p<0.001). OARSI scoring for collagen pathology differed significantly (p<0.05) between early and late OA groups and correlated positively (r = 0.41, p<0.05) with apparent density.
Conclusion
While changes in proteoglycan levels partially explain variance in apparent density, degree of superficial zone loss influences the uptake when using a short-term exposure time to evaluate cartilage and OA progression.