T1ρ Dispersion in Articular Cartilage: Relationship to Material Properties and Macromolecular Content. (April 2015)

• Record Type: Journal Article
• Authors: Keenan, Kathryn E.; Besier, Thor F.; Pauly, John M.; Smith, R. Lane; Delp, Scott L.; Beaupre, Gary S.; Gold, Garry E.
• Is Part Of: Cartilage. Volume 6:Number 2(2015)
• Page Start: 113
• Page End: 122
• Publication Date: 2015-04
• Subjects: T1ρ dispersion -- articular cartilage -- initial elastic modulus -- proteoglycan -- collagen; Cartilage -- Periodicals; 616.7
• DOI: 10.1177/1947603515569529
• Languages: English
• ISSNs: 1947-6035

Abstract

Objective: This study assessed T1ρ relaxation dispersion, measured by magnetic resonance imaging (MRI), as a tool to noninvasively evaluate cartilage material and biochemical properties. The specific objective was to answer two questions: (1) does cartilage initial elastic modulus ( E 0 ) correlate with T1ρ dispersion effects and (2) does collagen or proteoglycan content correlate with T1ρ dispersion effects? Design: Cadaveric patellae with and without visible cartilage damage on conventional MR were included. T2 and T1ρ relaxation times at 500 and 1000 Hz spin-lock field amplitudes were measured. We estimated T1ρ dispersion effects by measuring T1ρ relaxation time at 500 and 1000 Hz and T2 relaxation time and using a new tool, the ratio T1ρ/T2. Cartilage initial elastic modulus, E 0, was measured from initial response of mechanical indentation creep tests. Collagen and proteoglycan contents were measured at the indentation test sites; proteoglycan content was measured by their covalently linked sulfated glycosaminoglycans (sGAG). Pearson correlation coefficients were determined, taking into account the clustering of multiple samples within a single patella specimen. Results: Cartilage initial elastic modulus, E 0, increased with decreasing values of T1ρ/T2 measurements at both 500 Hz ( P = 0.034) and 1000 Hz ( P = 0.022). 1/T1ρ relaxation time (500 Hz) increased with increasing sGAG content ( P = 0.041). Conclusions: T1ρ/T2 ratio, a new tool, and cartilage initial elastic modulus are both measures of water–protein interactions, are dependent on the cartilage structure, and were correlated in this study.