Physics and Astronomy Department, University of Bologna, Bologna, Italy.
Department of Radiology, Stanford University, Stanford, CA, USA.
Magn Reson Med. 2021 Jun;85(6):3353-3369. doi: 10.1002/mrm.28648. Epub 2020 Dec 22.
Single-sided H-NMR is proposed for the estimation of morphological parameters of trabecular bone, and potentially the detection of pathophysiological alterations of bone structure. In this study, a new methodology was used to estimate such parameters without using an external reference signal, and to study intratrabecular and intertrabecular porosities, with a view to eventually scanning patients.
Animal trabecular bone samples were analyzed by a single-sided device. The Carr-Purcell-Meiboom-Gill sequence of H nuclei of fluids, including marrow, confined inside the bone, was analyzed by quasi-continuous T distributions and separated into two H pools: short and long T components. The NMR parameters were estimated using models of trabecular bone structure, and compared with the corresponding micro-CT.
Without any further assumptions, the internal reference parameter (short T signal intensity fraction) enabled prediction of the micro-CT parameters BV/TV (volume of the trabeculae/total sample volume) and BS/TV (external surface of the trabeculae/total sample volume) with linear correlation coefficient >0.80. The assignment of the two pools to intratrabecular and intertrabecular components yielded an estimate of average intratrabecular porosity (33 ± 5)%. Using the proposed models, the NMR-estimated BV/TV and BS/TV were found to be linearly related to the corresponding micro-CT values with high correlation (>0.90 for BV/TV; >0.80 for BS/TV) and agreement coefficients.
Low-field, low-cost portable devices that rely on intrinsic magnetic field gradients and do not use ionizing radiation are viable tools for in vitro preclinical studies of pathophysiological structural alterations of trabecular bone.
提出了单边 H-NMR 用于估计小梁骨的形态参数，并有可能检测到骨结构的病理生理改变。在这项研究中，使用了一种新的方法来估计这些参数，而无需使用外部参考信号，并研究了骨小梁内和骨小梁间的孔隙率，以期最终对患者进行扫描。
使用单边设备分析动物小梁骨样本。对包含骨髓在内的骨内流体的 H 核的 Carr-Purcell-Meiboom-Gill 序列进行了分析，采用准连续 T 分布进行了分析，并将其分为两个 H 池：短 T 和长 T 成分。使用小梁骨结构模型来估计 NMR 参数，并与相应的 micro-CT 进行比较。
无需进一步假设，内部参考参数（短 T 信号强度分数）能够以线性相关系数>0.80 预测 micro-CT 参数 BV/TV（小梁体积/总样本体积）和 BS/TV（小梁外表面/总样本体积）。将两个池分配到骨小梁内和骨小梁间成分，得出平均骨小梁内孔隙率（33±5）%的估计值。使用所提出的模型，NMR 估计的 BV/TV 和 BS/TV 与相应的 micro-CT 值呈线性相关，相关系数高（BV/TV>0.90；BS/TV>0.80），且一致性系数也较高。
基于固有磁场梯度且不使用电离辐射的低成本、低场便携式设备是小梁骨病理生理结构改变的体外临床前研究的可行工具。
