Sodium MRI of human articular cartilage of the wrist: a feasibility study on a clinical 3T MRI scanner

To measure sodium relaxation times and concentrations in human wrists on a clinical magnetic resonance imaging (MRI) scanner with a density-adapted radial sequence. Sodium MRI of human wrists was conducted on a 3T MR system using a dual-tuned 1H/23Na surface coil. We performed two studies with 10 volunteers each investigating either sodium T1 (study 1) or sodium T2* (study 2) relaxation times in the radiocarpal joint (RCJ) and midcarpal joint (MCJ). Sodium concentrations of both regions were determined. No differences for transversal of longitudinal relaxation times were found between RCJ and MCJ (T2,s*(RCJ) = (0.9 ± 0.4) ms; T2,s*(MCJ) = (0.9 ± 0.3) ms; T2,l*(RCJ) = (14.9 ± 0.9) ms; T2,l*(MCJ) = (13.9 ± 1.1) ms; T1(RCJ) = (19.0 ± 2.4) ms; T1(MCJ) = (18.5 ± 2.1) ms). Sodium concentrations were (157.7 ± 28.4) mmol/l for study 1 and (159.8 ± 29.1) mmol/l for study 2 in the RCJ, and (172.7 ± 35.6) mmol/l for study 1 and (163.4 ± 26.3) mmol/l for study 2 in the MCJ. We successfully determined sodium relaxation times and concentrations of the human wrist on a 3T MRI scanner.