Manhard Mary Kate, Harkins Kevin D, Gochberg Daniel F, Nyman Jeffry S, Does Mark D
Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.
Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA.
Magn Reson Med. 2017 Mar;77(3):945-950. doi: 10.1002/mrm.26605. Epub 2017 Jan 16.
MRI of cortical bone has the potential to offer new information about fracture risk. Current methods are typically performed with 3D acquisitions, which suffer from long scan times and are generally limited to extremities. This work proposes using 2D UTE with half pulses for quantitatively mapping bound and pore water in cortical bone.
Half-pulse 2D UTE methods were implemented on a 3T Philips Achieva scanner using an optimized slice-select gradient waveform, with preparation pulses to selectively image bound or pore water. The 2D methods were quantitatively compared with previously implemented 3D methods in the tibia in five volunteers.
The mean difference between bound and pore water concentration acquired from 3D and 2D sequences was 0.6 and 0.9 mol H/L (3 and 12%, respectively). While 2D pore water methods tended to slightly overestimate concentrations relative to 3D methods, differences were less than scan-rescan uncertainty and expected differences between healthy and fracture-prone bones.
Quantitative bound and pore water concentration mapping in cortical bone can be accelerated by 2 orders of magnitude using 2D protocols with optimized half-pulse excitation. Magn Reson Med 77:945-950, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
皮质骨的磁共振成像（MRI）有潜力提供有关骨折风险的新信息。当前方法通常采用三维采集，存在扫描时间长的问题，且一般仅限于四肢。本研究提出使用具有半脉冲的二维UTE（UTE：超声激发回波）对皮质骨中的结合水和孔隙水进行定量成像。
在3T飞利浦Achieva扫描仪上，采用优化的层面选择梯度波形，实施半脉冲二维UTE方法，并使用准备脉冲来选择性地对结合水或孔隙水成像。将二维方法与先前在五名志愿者胫骨中实施的三维方法进行定量比较。
从三维和二维序列获得的结合水和孔隙水浓度的平均差异分别为0.6和0.9摩尔H/L（分别为3%和12%）。相对于三维方法，二维孔隙水方法往往会略微高估浓度，但差异小于扫描重扫不确定性以及健康骨骼和易骨折骨骼之间的预期差异。
使用具有优化半脉冲激发的二维方案，皮质骨中结合水和孔隙水浓度的定量成像可加快两个数量级。《磁共振医学》77:945 - 950, 2017。© 2017国际磁共振医学学会。
