Bredella Miriam A, Daley Scott M, Kalra Mannudeep K, Brown J Keenan, Miller Karen K, Torriani Martin
From the Department of Radiology (M.A.B., S.M.D., M.K.K., M.T.) and Neuroendocrine Unit (K.K.M.), Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Yawkey 6E, Boston, MA 02114; and Mindways Software, Austin, Tex (J.K.B.).
Radiology. 2015 Oct;277(1):230-5. doi: 10.1148/radiol.2015142876. Epub 2015 May 19.
To test the performance of dual-energy computed tomography (CT) in the assessment of marrow adipose tissue (MAT) content of the lumbar spine by using proton (hydrogen 1 [(1)H]) magnetic resonance (MR) spectroscopy as a reference standard and to determine the influence of MAT on the assessment of bone mineral density (BMD).
This study was institutional review board approved and complied with HIPAA guidelines. Written informed consent was obtained. Twelve obese osteopenic but otherwise healthy subjects (mean age ± standard deviation, 43 years ± 13) underwent 3-T (1)H MR spectroscopy of the L2 vertebra by using a point-resolved spatially localized spectroscopy sequence without water suppression. The L2 vertebra was scanned with dual-energy CT (80 and 140 kV) by using a dual-source multi-detector row CT scanner with a calibration phantom. Mean basis material composition relative to the phantom was estimated in the L2 vertebra. Volumetric BMD was measured with and without correction for MAT. Bland-Altman 95% limits of agreement and Pearson correlation coefficients were calculated.
There was excellent agreement between (1)H MR spectroscopy and dual-energy CT, with a mean difference in fat fraction of -0.02 between the techniques, with a 95% confidence interval of -0.24, 0.20. There was a strong correlation between marrow fat fraction obtained with (1)H MR spectroscopy and that obtained with dual-energy CT (r = 0.91, P < .001). The presence of MAT led to underestimation of BMD, and this bias increased with increasing MAT content (P < .001).
Dual-energy CT can be used to assess MAT content and BMD of the lumbar spine in a single examination and provides data that closely agree and correlate with (1)H MR spectroscopy data.
以质子（氢1 [¹H]）磁共振（MR）波谱作为参考标准，测试双能计算机断层扫描（CT）在评估腰椎骨髓脂肪组织（MAT）含量中的性能，并确定MAT对骨密度（BMD）评估的影响。
本研究经机构审查委员会批准，并符合HIPAA指南。获得了书面知情同意书。12名肥胖但骨质减少但其他方面健康的受试者（平均年龄±标准差，43岁±13岁）使用不进行水抑制的点分辨空间定位波谱序列，对L2椎体进行了3-T ¹H MR波谱检查。使用带有校准体模的双源多排探测器CT扫描仪，对L2椎体进行双能CT（80 kV和140 kV）扫描。估计L2椎体相对于体模的平均基础物质组成。在有和没有对MAT进行校正的情况下测量体积BMD。计算Bland-Altman 95%一致性界限和Pearson相关系数。
¹H MR波谱和双能CT之间具有极好的一致性，两种技术之间的脂肪分数平均差异为-0.02，95%置信区间为-0.24, 0.20。¹H MR波谱获得的骨髓脂肪分数与双能CT获得的骨髓脂肪分数之间存在很强的相关性（r = 0.91，P < .001）。MAT的存在导致BMD被低估，并且这种偏差随着MAT含量的增加而增加（P < .001）。
双能CT可用于在一次检查中评估腰椎的MAT含量和BMD，并提供与¹H MR波谱数据密切一致且相关的数据。
