title: Contrast enhanced CT attenuation correlates with the GAG content of bovine meniscus.
abstract: We determined whether contrast-enhanced computed tomography (CECT) attenuation obtained using a µCT scanner correlated with the glycosaminoglycan (GAG) content and distribution in ex vivo bovine menisci. Bovine samples were immersed in different concentrations of the contrast agents CA4+ and Ioxaglate, and the µCT images were compared to Safranin-O staining. CA4+ and Ioxaglate diffusion-in kinetics and the correlation between their CECT attenuations and GAG content were investigated. CA4+ and Ioxaglate both reached steady state in the meniscal regions within 95 h, with tau values of 20.6 ± 3.98 and 25.9 ± 3.71 h (mean ± SD), respectively. Both agents diffused preferentially through the proximal and secondarily through the distal surface. The CA4+ CECT attenuation was strongly and positively correlated with the GAG content of the meniscus regions (R(2)  = 0.89, p < 0.001) at low concentrations (12 mgI/ml), while the Ioxaglate CECT attenuation was moderately and negatively correlated with the GAG content (R(2)  = 0.51, p = 0.03) at 60 mgI/ml. CECT can image ex vivo menisci, and the CA4+, compared to Ioxaglate, enhanced attenuation strongly correlates with the GAG content and distribution in bovine meniscus.
authors.affiliation: Department of Biomedical Engineering and Chemistry, Boston University, Boston, Massachusetts; Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors.forename: Bejamin A
authors.initials: BA
authors.lastname: Lakin
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Grasso
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Stewart
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Freedman
authors.forename: Brian D
authors.initials: BD
authors.lastname: Snyder
authors.forename: Mark W
authors.initials: MW
authors.lastname: Grinstaff
mesh_terms: D000818:Animals; D002417:Cattle; D003287:Contrast Media; D006025:Glycosaminoglycans / Q000032:analysis*; D007485:Ioxaglic Acid; D008592:Menisci, Tibial / Q000737:chemistry / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D006025:Glycosaminoglycans; D007485:Ioxaglic Acid
keywords: GAG; bovine; computed tomography; meniscus; osteoarthritis