Characterization of proteoglycan depletion in articular cartilage using two-dimensional time domain nuclear magnetic resonance

• Published in: Magnetic resonance in medicine 2005-12, Vol.54 (6), p.1397-1402
• Main Authors: Lattanzio, Pierre-Jean, Marshall, K. Wayne, Damyanovich, Andrei Z., Peemoeller, Hartwig
• Format: Article
• Language: English
• Subjects: Algorithms; Animals; cartilage; Cartilage, Articular - metabolism; Cattle; In Vitro Techniques; Knee Joint - metabolism; Magnetic Resonance Spectroscopy - methods; magnetization exchange; Metabolic Clearance Rate; NMR; Proteoglycans - metabolism; T1ρ
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.20692

In vitro proteoglycan (PG) depletion in the 20–40% range (enzymatic PG depletion of normal cartilage in the early osteoarthritis (OA) PG depletion range) was investigated in articular cartilage using 2D time domain NMR relaxation techniques. Spin–lattice relaxation times were measured at low fields (T1ρ) and at high fields (T1) using nonselective and selective excitation pulse sequences. The short relaxation time magnetization components in T1ρ (∼8% signal) and nonselective T1 (∼5% signal) experiments were significantly altered with PG degradation. In addition, a magnetization component (∼5% signal) with a “fast ” T1 ∼ 7 ms was observed in the T1 experiment involving selective excitation. This fast T1 was at least 10 times shorter than the short T1 in the nonselective experiment and was associated with a strong magnetization exchange mechanism between collagen and PG. The results suggest that T1ρ and T1 (nonselective and selective) relaxation based MRI techniques, which focus on the short relaxation time magnetization components, have the potential of detecting molecular abnormalities associated with early OA earlier than single, long relaxation time component approaches. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.