科研之友
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摘要
Magnetization transfer (MT) imaging is one way to indirectly assess pools of protons with fast transverse relaxation. However, conventional MT imaging sequences are not applicable to short T-2 tissues such as cortical bone. Ultrashort echo time (UTE) sequences with T-E values as low as 8 mu s can detect signals from different water components in cortical bone. In this study we aim to evaluate two-dimensional UTE-MT imaging of cortical bone and its application in assessing cortical bone porosity as measured by micro-computed tomography (CT) and biomechanical properties. In total, 38 human cadaveric distal femur and proximal tibia bones were sectioned to produce 122 rectangular pieces of cortical bone for quantitative UTE-MT MR imaging, CT, and biomechanical testing. Off-resonance saturation ratios (OSRs) with a series of MT pulse frequency offsets (f) were calculated and compared with porosity assessed with CT, as well as elastic (modulus, yield stress, and strain) and failure (ultimate stress, failure strain, and energy) properties, using Pearson correlation and linear regression. A moderately strong negative correlation was observed between OSR and CT porosity (R-2=0.46-0.51), while a moderate positive correlation was observed between OSR and yield stress (R-2=0.25-0.30) and failure stress (R-2=0.31-0.35), and a weak positive correlation (R-2=0.09-0.12) between OSR and Young's modulus at all off-resonance saturation frequencies. OSR determined with the UTE-MT sequence provides quantitative information on cortical bone and is sensitive to CT porosity and biomechanical function.
- 出版日期2015-7
- 单位中国医学科学院北京协和医院
