Martin Jarad, Nicholson Geoffrey, Cowin Gary, Ilente Clare, Wong Winnie, Kennedy Dominic
Calvary Mater Newcastle, Newcastle, New South Wales, Australia; School of Medicine, University of Queensland, Toowoomba, Queensland, Australia; Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia.
J Med Imaging Radiat Oncol. 2014 Apr;58(2):155-63. doi: 10.1111/1754-9485.12143. Epub 2013 Dec 23.
Vertebral body fat fraction (FF) has been found to vary between lumbar vertebrae using magnetic resonance spectroscopy (MRS). We aim to more quickly assess a larger number of adjacent vertebrae using a single T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) sequence.
Five men had dual-energy X-ray absorptometry (DEXA) and 1.5-T MR scans performed. MRS was performed at L3, and a sagittal IDEAL sequence was also performed, resulting in separate fat-only and water-only readings from T10 to S2. For the IDEAL measurements, two independent observers followed a set reading protocol, with five observations each per vertebra. Intra- and interobserver variability were assessed as deviations from the mean within and between observers, respectively.
For FF measurements there was limited intra-observer variation, with observers being on average within 3.4% of the pooled mean value. Similarly, there was good interobserver agreement, with an average variation of 2.1%. All men showed a reduction in FF of 1.6-7% between L5 and S1. Otherwise, there was a trend of increasing FF moving inferiorly from T10 to S2. This averaged 2.7% per vertebra (range 1.1-3.8%) and may not have been dependent on MRS-measured FF at the L3 level. There was poor correlation between MRS-measured FF at L2-4 and bone mineral density measured using DEXA (R(2) = 0.06).
IDEAL measurements are generally reproducible between observers following a set protocol. There appears to be a gradient in FF moving from T10 to S2, with S1 showing a consistent decrease. This variation may better describe overall marrow function than a single-vertebra reading.
利用磁共振波谱（MRS）已发现腰椎椎体的脂肪分数（FF）存在差异。我们旨在使用具有回波不对称和最小二乘估计的水和脂肪的单T2加权迭代分解（IDEAL）序列，更快地评估更多相邻椎体。
对5名男性进行了双能X线吸收法（DEXA）和1.5-T磁共振扫描。在L3水平进行MRS检查，并同时进行矢状面IDEAL序列扫描，从而获得从T10至S2单独的仅脂肪和仅水的读数。对于IDEAL测量，两名独立观察者遵循既定的读数方案，每个椎体各进行5次观察。观察者内和观察者间的变异性分别评估为观察者内部和之间相对于平均值的偏差。
对于FF测量，观察者内变异有限，观察者平均偏差在合并平均值的3.4%以内。同样，观察者间一致性良好，平均变异为2.1%。所有男性在L5和S1之间的FF均降低了1.6%-7%。此外，从T10至S2，FF有向下增加的趋势。每个椎体平均增加2.7%（范围为1.1%-3.8%），且可能不依赖于L3水平MRS测量的FF。L2-4水平MRS测量的FF与DEXA测量的骨矿物质密度之间的相关性较差（R(2) = 0.06）。
遵循既定方案时，观察者之间IDEAL测量结果通常具有可重复性。从T10至S2，FF似乎存在梯度变化，S1显示出持续下降。与单个椎体读数相比，这种变化可能更好地描述整体骨髓功能。
