Prediction of glycosaminoglycan content in human cartilage by age, T1ρ and T2 MRI

Abstract

Summary Objective A relationship between T1ρ relaxation time and glycosaminoglycan (GAG) content has been demonstrated in chemically degraded bovine cartilage, but has not been demonstrated with quantitative biochemistry in human cartilage. A relationship has also been established between T2 relaxation time in cartilage and osteoarthritis severity. We hypothesized that T1ρ relaxation time would be associated with GAG content in human cartilage with normal T2 relaxation times. Methods T2 relaxation time, T1ρ relaxation time, and glycosaminoglycan as a percentage of wet weight (sGAG) were measured for top and bottom regions at seven anatomical locations in twenty-one human cadaver patellae. For our analysis, T2 relaxation time was classified as normal or elevated based on a threshold defined by the mean plus one standard deviation of the T2 relaxation time for all samples. Results In the normal T2 relaxation time subset, T1ρ relaxation time correlated with sGAG in the full-thickness and bottom regions, but only marginally in the top region alone. sGAG decreased significantly with age in all regions. Conclusion In the subset of cartilage specimens with normal T2 relaxation time, T1ρ relaxation time was inversely associated with sGAG content, as hypothesized. A predictive model, which accounts for T2 relaxation time and the effects of age, might be able to determine longitudinal trends in GAG content in the same person based on T1ρ relaxation time maps.

Is T1ρ Mapping an Alternative to Delayed Gadolinium-enhanced MR Imaging of Cartilage in the Assessment of Sulphated Glycosaminoglycan Content in Human Osteoarthritic Knees? An in Vivo Validation Study

“…Although both dGEMRIC and T1r mapping are increasingly used as outcome measures for cartilage biochemical composition in clinical osteoarthritis research, they have been validated mainly in vitro (9,10) or ex vivo (11,12) by using bovine and cadaveric human cartilage. In vivo validation was performed in only one study of dGEM-RIC (13) and only two studies of T1r mapping (14,15).…”

MRI of Hip Cartilage: Joint Morphology, Structure, and Composition

“…Elevated T1q values reflect areas of proteoglycan depletion [17]. The utility of this technique in detecting early cartilage degeneration has been documented at clinical field strengths [10,15] (Fig. 4).…”

Anterior Delayed Gadolinium-enhanced MRI of Cartilage Values Predict Joint Failure After Periacetabular Osteotomy

“…Other studies have shown T1q is specific to GAG loss [36,59,76]. The most recent study by Keenan et al [30] found T2 and T1q values correlated, and when T2 effects were isolated by looking at tissue only with T2 within normal range, T1q correlated with GAG content. They concluded T2 relaxation time should be incorporated into a predictive model when using T1q data to estimate GAG content.…”