Multiparametric MRI assessment of human articular cartilage degeneration: Correlation with quantitative histology and mechanical properties

Abstract

Purpose To evaluate the sensitivity of quantitative MRI techniques (T1, T1,Gd, T2, continous wave (CW) T1ρ dispersion, adiabatic T1ρ, adiabatic T2ρ, RAFF and inversion-prepared magnetization transfer (MT)) for assessment of human articular cartilage with varying degrees of natural degeneration. Methods Osteochondral samples (n = 14) were obtained from the tibial plateaus of patients undergoing total knee replacement. MRI of the specimens was performed at 9.4 T and the relaxation time maps were evaluated in the cartilage zones. For reference, quantitative histology, OARSI grading and biomechanical measurements were performed and correlated with MRI findings. Results All MRI parameters, except T1,Gd, showed statistically significant differences in tangential and full-thickness ROIs between early and advanced osteoarthritis (OA) groups, as classified by OARSI grading. CW-T1ρ showed significant dispersion in all ROIs and featured classical laminar structure of cartilage with spin-lock powers below 1000 Hz. Adiabatic T1ρ, T2ρ, CW-T1ρ, MT and RAFF correlated strongly with OARSI grade and biomechanical parameters. Conclusion MRI parameters were able to differentiate between early and advanced OA. Furthermore, rotating frame methods, namely adiabatic T1ρ, adiabatic T2ρ, CW-T1ρ and RAFF, as well as MT experiment correlated strongly with biomechanical parameters and OARSI grade, suggesting high sensitivity of the parameters for cartilage degeneration.

Multi‐parametric MRI characterization of enzymatically degraded articular cartilage

“…Recently, an array of novel methods for probing the interactions between tissue macromolecules and water has been introduced . Adiabatic rotating frame relaxation methods measure the longitudinal and transverse relaxation times ( T 1 ρ and T 2 ρ ) in the rotating frame of reference during adiabatic rotation .…”

“…Aside from the rotating‐frame methods, a modification to traditional MT method was recently proposed: inclusion of an inversion preparation pulse prior to off‐resonance irradiation, which allows markedly larger dynamic range for signal evolution. These novel techniques have been successfully applied to study brain tissue in both animal models and humans, and the first results on the application of these techniques to study cartilage degeneration have been promising …”

Elevated adiabatic T1ρ and T2ρ in articular cartilage are associated with cartilage and bone lesions in early osteoarthritis: A preliminary study

“…Specifically, elevated T 2 values have been determined in patients with cartilage lesions and alteration of subchondral bone, while increased T 1ρ of cartilage have been observed in subjects with AC lesions . Ad T 1ρ and Ad T 2ρ relaxation time constants have been shown to increase with AC degeneration in vitro . In this study, Ad T 1ρ and Ad T 2ρ and T 2 were significantly increased in multiple cartilage sites presenting lesions.…”

“…During an adiabatic RF pulse both amplitude and frequency of the pulse vary in time, therefore Ad T 1ρ and Ad T 2ρ are sensitive to an extended range of slow frequency macromolecule–water interactions and, in turn, potentially more sensitive to extracellular matrix alterations. At higher field strengths elevated Ad T 1ρ and Ad T 2ρ have been observed in human degenerated cartilage and showed better accuracy for discriminating mild and advanced cartilage degeneration as compared to T 2 and T 1ρ relaxation measurements . The association of Ad T 1ρ and Ad T 2ρ with clinically relevant OA features has not been studied in vivo yet.…”

“…During an adiabatic pulse, both amplitude and frequency are varied in time, therefore Ad T 1ρ and Ad T 2ρ are sensitive over a wide range of slow molecular interactions . Ad T 1ρ and Ad T 2ρ mapping have demonstrated high sensitivity to cartilage degeneration in several preclinical studies and degenerated human cartilage specimens . They have been shown to strongly correlate with OA histopathology and AC biomechanical parameters, and have better sensitivity to OA cartilage changes as compared to CW‐ T 1ρ or T 2 relaxation time .…”