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Evaluation of bound and pore water in cortical bone using ultrashort‐TE MRI
Author(s) -
Chen Jun,
Grogan Shawn P.,
Shao Hongda,
D'Lima Darryl,
Bydder Graeme M.,
Wu Zhihong,
Du Jiang
Publication year - 2015
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3436
Subject(s) - bound water , cortical bone , distilled water , chemistry , bone mineral , body water , matrix (chemical analysis) , gravimetric analysis , free water , tritiated water , porosity , chromatography , anatomy , osteoporosis , geology , medicine , tritium , physics , geotechnical engineering , organic chemistry , body weight , molecule , nuclear physics
Bone water exists in different states with the majority bound to the organic matrix and to mineral, and a smaller fraction in ‘free’ form in the pores of cortical bone. In this study, we aimed to develop and evaluate ultrashort‐TE (UTE) MRI techniques for the assessment of T 2 *, T 1 and concentration of collagen‐bound and pore water in cortical bone using a 3‐T clinical whole‐body scanner. UTE MRI, together with an isotope study using tritiated and distilled water (THO–H 2 O) exchange, as well as gravimetric analysis, were performed on ten sectioned bovine bone samples. In addition, 32 human cortical bone samples were prepared for comparison between the pore water concentration measured with UTE MRI and the cortical porosity derived from micro‐computed tomography (μCT). A short T 2 * of 0.27 ± 0.03 ms and T 1 of 116 ± 6 ms were observed for collagen‐bound water in bovine bone. A longer T 2 * of 1.84 ± 0.52 ms and T 1 of 527 ± 28 ms were observed for pore water in bovine bone. UTE MRI measurements showed a pore water concentration of 4.7–5.3% by volume and collagen‐bound water concentration of 15.7–17.9% in bovine bone. THO–H 2 O exchange studies showed a pore water concentration of 5.9 ± 0.6% and collagen‐bound water concentration of 18.1 ± 2.1% in bovine bone. Gravimetric analysis showed a pore water concentration of 6.3 ± 0.8% and collagen‐bound water concentration of 19.2 ± 3.6% in bovine bone. A mineral water concentration of 9.5 ± 0.6% was derived in bovine bone with the THO–H 2 O exchange study. UTE‐measured pore water concentration is highly correlated ( R 2 = 0.72, p < 0.0001) with μCT porosity in the human cortical bone study. Both bovine and human bone studies suggest that UTE sequences could reliably measure collagen‐bound and pore water concentration in cortical bone using a clinical scanner. Copyright © 2015 John Wiley & Sons, Ltd.