Techawiboonwong Aranee, Song Hee Kwon, Leonard Mary B, Wehrli Felix W
Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania Medical Center, 3400 Spruce St, 1 Founders, MRI Education Center, Philadelphia, PA 19104, USA.
Radiology. 2008 Sep;248(3):824-33. doi: 10.1148/radiol.2482071995. Epub 2008 Jul 15.
To develop and evaluate a method based on ultrashort echo-time radial magnetic resonance (MR) imaging to quantify bone water (BW) concentration as a new metric of bone quality in human cortical bone in vivo.
Human subject studies were institutional review board approved and HIPAA compliant; informed consent was obtained. Cortical BW concentration was determined with custom-designed MR imaging sequences at 3.0 T and was validated in sheep and human cortical bone by using exchange of native water with deuterium oxide (D(2)O). The submillisecond T2* of BW requires correction for relaxation losses during the radiofrequency pulse. BW was measured at the tibial midshaft in healthy pre- and postmenopausal women (mean age, 34.6 and 69.4 years, respectively; n = 5 in each group) and in patients receiving maintenance hemodialysis (mean age, 51.8 years; n = 6) and was compared with bone mineral density (BMD) at the same site at peripheral quantitative computed tomography, as well as with BMD of the lumbar spine and hip at dual x-ray absorptiometry. Data were analyzed by using the Pearson correlation coefficient and two-sided t tests as appropriate.
Excellent agreement was obtained ex vivo between the water displaced by using D(2)O exchange and water measured with respect to a reference sample (r(2) = 0.99, P < .001). In vivo, BW in the postmenopausal group was greater by 65% (28.7% +/- 1.3 [standard deviation] vs 17.4% +/- 2.2, P < .001) than in the premenopausal group, and patients with renal osteodystrophy had higher BW (41.4% +/- 9.6) than the premenopausal group by 135% (P < .001) and the postmenopausal group by 43% (P = .02). BMD showed an opposite behavior, with much smaller group differences. Because the majority of BW is in the pore system of cortical bone, this parameter provides a surrogate measure for cortical porosity.
A new MR imaging-based method for quantifying BW noninvasively has been demonstrated.
开发并评估一种基于超短回波时间径向磁共振（MR）成像的方法，用于在体定量测定人体皮质骨中的骨水（BW）浓度，将其作为骨质量的一项新指标。
人体受试者研究经机构审查委员会批准且符合健康保险流通与责任法案（HIPAA）要求；已获得知情同意。采用定制设计的MR成像序列在3.0 T场强下测定皮质骨BW浓度，并通过重水（D₂O）与天然水的交换在绵羊和人体皮质骨中进行验证。BW亚毫秒级的T2* 需要校正射频脉冲期间的弛豫损失。在健康绝经前和绝经后女性（平均年龄分别为34.6岁和69.4岁；每组n = 5）以及接受维持性血液透析的患者（平均年龄51.8岁；n = 6）的胫骨干中部测量BW，并将其与外周定量计算机断层扫描同一部位的骨矿物质密度（BMD）以及双能X线吸收法测量的腰椎和髋部BMD进行比较。数据采用Pearson相关系数及适当的双侧t检验进行分析。
在体外，通过D₂O交换置换的水与相对于参考样本测量的水之间取得了极佳的一致性（r² = 0.99，P <.001）。在体研究中，绝经后组的BW比绝经前组高65%（28.7%±1.3 [标准差] 对17.4%±2.2，P <.001），肾性骨营养不良患者的BW（41.4%±9.6）比绝经前组高135%（P <.001），比绝经后组高43%（P =.02）。BMD表现出相反的趋势，组间差异小得多。由于大部分BW存在于皮质骨的孔隙系统中，该参数可作为皮质骨孔隙率的替代指标。
已证明一种基于MR成像的无创定量BW的新方法。
