Individual and cumulative measures of knee joint load associate with T2 relaxation times of knee cartilage in young, uninjured individuals: A pilot study.

BACKGROUND: Articular cartilage structure and chondrocyte health are sensitive and reliant on dynamic joint loading during activities. The purpose of this pilot study was to determine the association between measures of individual and cumulative knee joint loading with T2 relaxation times in the knee cartilage of young individuals without knee injury. METHODS: Twelve participants (17-30 years old) without history of knee injury or surgery completed MRI, physical activity (PA), and biomechanical gait testing. T2 relaxation times were calculated in the cartilage within the patella and lateral and medial compartments. Accelerometry was used to measure mean daily step counts, minutes of PA, and % sedentary time over 7 days. Vertical ground reaction force, external knee joint moments and peak knee flexion angle were measured during stance phase of gait using three-dimensional motion capture. Cumulative knee joint loading was calculated as daily step count by external knee joint moment impulse. The relationship between measures of knee joint loading and T2 relaxation times was assessed using Pearson correlations. RESULTS: Higher T2 relaxation times in the femoral and tibial cartilage were consistently correlated to greater body mass, daily step counts, moderate and vigorous PA, and peak knee joint moments (r = 0.10-0.84). Greater cumulative knee flexion and adduction loading was associated with higher T2 relaxation times in the femoral and tibial cartilage (r = 0.16-0.65). CONCLUSION: Preliminary findings suggest that individual loading factors and cumulative knee joint loading are associated with higher T2 relaxation times in the articular cartilage of young, healthy knees.

Longitudinal magnetic resonance spectroscopic imaging of primary progressive multiple sclerosis patients treated with glatiramer acetate: multicenter study.

Multicenter proton magnetic resonance spectroscopic imaging (MRSI) studies were performed on 58 primary progressive multiple sclerosis (PPMS) patients from four centers for investigating the efficacy of glatiramer acetate (GA) treatment. These patients were drawn from 943 subjects who participated in the PROMiSe trial. In these MRSI studies, patients were followed over a period of 3 years. MRSI data were acquired by all the centers using the same pulse sequence, and spectral analysis was performed at a single site using a customized analysis software package. Quantitative metabolite ratios, N-acetyl aspartate (NAA)/creatine (Cr) and choline (Cho)/Cr, were compared between GA-treated and placebo-treated PPMS patients. There was no significant difference in metabolite ratios between GA-treated and placebo-treated patients. The difference in metabolite ratios between the normal-appearing tissues (NAT) and lesion-containing regions (LCR) in GA treated patients was not significantly different from placebo treated patients. Strong lipid resonances, even in the absence of lesions, were observed on MRSI data in both gray matter and white matter in placebo- and GA-treated PPMS patients. No significant difference in number of patients with lipids between the two groups over a period of 3 years was found.