Bone
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Cortical bone assessment using magnetic resonance imaging (MRI) has recently received great attention in an effort to avoid the potential harm associated with ionizing radiation-based techniques. Ultrashort echo time MRI (UTE-MRI) techniques can acquire signal from major hydrogen proton pools in cortical bone, including bound and pore water, as well as from the collagen matrix. This study aimed to develop and evaluate the feasibility of a technique for mapping bound water, pore water, and collagen proton densities in human cortical bone ex vivo and in vivo using three-dimensional UTE Cones (3D-UTE-Cones) MRI. ⋯ MMPD showed strong correlation with age in specimens from female donors (R = -0.91, p = 0.03, n = 5). The presented comprehensive 3D-UTE-Cones imaging protocol allows quantitative mapping of protons in major pools of cortical bone ex vivo and in vivo. PWPD and MMPD can serve as potential novel biomarkers to assess bone matrix and microstructure, as well as bone age- or injury-related variations.
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Spinal cord injury (SCI) induces an acute alteration in bone metabolism. Although the aetiology of the bone disturbances is not precisely known, immobilisation reduces mechanical loading and the morphology of osteocytes, which are the primary mechanosensors. Periostin and sclerostin are secreted mostly by osteocytes and are involved in bone's mechanical response. ⋯ This study showed for the first time that individuals with SCI presented higher periostin levels than healthy controls only during the acute phase. Conversely, sclerostin levels are lower whatever the post-injury time. Fractures and densitometric osteoporosis were not associated with differences in these two biological markers, whereas paraplegia vs. tetraplegia and fragility fracture status seemed to influence sclerostin levels only.