title: Cationic contrast agents improve quantification of glycosaminoglycan (GAG) content by contrast enhanced CT imaging of cartilage.
abstract: Minimally invasive and non-destructive methods to quantify glycosaminoglycans (GAGs) in articular cartilage extracellular matrix are of significant interest for the biochemical analysis of cartilage and diagnosis and tracking of osteoarthritis in vivo. Here, we report the use of cationic iodinated contrast agents in comparison to conventional anionic contrast agents for the quantitative monitoring of GAG concentrations with peripheral quantitative computed tomography. Using an ex vivo bovine osteochondral plug model, the cationic contrast agents were evaluated for their ability to distribute into articular cartilage and generate a positive relationship with GAG content. The cationic agents resulted in much higher equilibrium X-ray attenuations in cartilage extracellular matrix (ECM) than anionic agents. Experiments with samples subjected to enzymatic GAG degradation demonstrated that the cationic agents were up to five times more sensitive (p = 0.0001) to changes in GAG content and had a 24% higher correlation (p = 0.002) compared to the anionic agent (R(2)  = 0.86, p < 0.0001 compared with R(2)  = 0.62, p = 0.004). The natural inhomogeneous distribution of GAGs in the ECM could clearly be identified in undegraded samples.
authors: Department of Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
authors: Prashant N
authors: PN
authors: Bansal
authors: Neel S
authors: NS
authors: Joshi
authors: Vahid
authors: V
authors: Entezari
authors: Bethany C
authors: BC
authors: Malone
authors: Rachel C
authors: RC
authors: Stewart
authors: Brian D
authors: BD
authors: Snyder
authors: Mark W
authors: MW
authors: Grinstaff
mesh_terms: D000818:Animals; D001549:Benzamides; D002358:Cartilage, Articular / Q000737:chemistry* / Q000000981:diagnostic imaging; D002412:Cations; D002417:Cattle; D003287:Contrast Media; D005109:Extracellular Matrix / Q000737:chemistry*; D006025:Glycosaminoglycans / Q000032:analysis*; D011817:Rabbits; D014057:Tomography, X-Ray Computed / Q000379:methods; D014283:Triiodobenzoic Acids
chemical_list: C558391:(ethylenediamine)-3-aminoacyl-2,4,6-triiodobenzoyl amide; D001549:Benzamides; D002412:Cations; D003287:Contrast Media; D006025:Glycosaminoglycans; D014283:Triiodobenzoic Acids