Ultrashort echo time magnetization transfer (UTE-MT) imaging of cortical bone.
Ultrashort echo time magnetization transfer (UTE-MT) imaging of cortical bone.
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DOI：
10.1002/nbm.3316
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发表时间：
2015-07
影响因子：
2.9
通讯作者：
Du J
中科院分区：
文献类型：
--
作者：
Chang EY;Bae WC;Shao H;Biswas R;Li S;Chen J;Patil S;Healey R;D'Lima DD;Chung CB;Du J
磁化转移(MT)成像是间接评估具有快速横向弛豫的质子池的一种方法。然而，常规的MT成像序列不适用于短T2的组织，如皮质骨。超短回波时间(UTE)序列具有低至8μ的TES，S可以检测到皮质骨中不同水分成分的信号。在这项研究中，我们旨在评估皮质骨的二维(2D)UTE-MT成像及其在μ、CT测量的皮质骨孔隙率和生物力学特性方面的应用。共对38例成人身体股骨远端和胫骨近端进行切片，制成长方形皮质骨，用于UUT-MT磁共振定量成像、μCT和生物力学测试。计算了一系列MT脉冲频率偏移(Δf)下的非共振饱和度，并与μCT评估的孔隙率以及弹性(弹性系数、屈服应力和应变)和破坏(极限应力、破坏应变和能量)进行了比较，使用皮尔逊相关和线性回归。在所有非共振饱和频率下，μCT孔隙度与OSR呈中等强负相关(R2=0.46~0.5 1)，与屈服应力(R2=0.2 5~0.30)和破坏应力(R2=0.31~0.35)呈中等正相关，与杨氏模量呈弱正相关(R2=0.0 9~0.12)。用UTE-MT序列测定的OSR提供了皮质骨的定量信息，并对μ、CT孔隙度和生物力学功能敏感。12 2例人皮质骨标本的UTE-MT成像：μCT皮质孔隙度(A)、杨氏模量(B)和屈服应力(C)与OSR之间的相关性OSR与孔隙度呈负相关，与杨氏模量、屈服应力呈正相关。
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 T2 tissues such as cortical bone. Ultrashort echo time (UTE) sequences with TEs as low as 8 μs can detect signals from different water components in cortical bone. In this study we aim to evaluate two-dimensional (2D) UTE-MT imaging of cortical bone and its application in assessing cortical bone porosity as measured by μCT 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, microcomputed tomography (μCT), and biomechanical testing. Off-resonance saturation ratios (OSR) with a series of MT pulse frequency offsets (Δf) were calculated and compared with porosity assessed with μCT, 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 moderate strong negative correlation was observed between OSR and μCT porosity (R2 = 0.46–0.51), while a moderate positive correlation was observed between OSR and yield stress (R2 = 0.25–0.30) and failure stress (R2 = 0.31–0.35), and a weak positive correlation (R2 = 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 μCT porosity and biomechanical function. UTE-MT imaging of 122 human cortical bone samples: correlation between OSR (at 1.5 kHz) and μCT cortical porosity (A), Young’s modulus (B) and yield stress (C). OSR is negatively correlated with porosity, and positively correlated with Young’s modulus and yield stress.