Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94107, USA.
J Bone Miner Res. 2013 Aug;28(8):1721-8. doi: 10.1002/jbmr.1950.
The goal of this magnetic resonance (MR) imaging study was to quantify vertebral bone marrow fat content and composition in diabetic and nondiabetic postmenopausal women with fragility fractures and to compare them with nonfracture controls with and without type 2 diabetes mellitus. Sixty-nine postmenopausal women (mean age 63 ± 5 years) were recruited. Thirty-six patients (47.8%) had spinal and/or peripheral fragility fractures. Seventeen fracture patients were diabetic. Thirty-three women (52.2%) were nonfracture controls. Sixteen women were diabetic nonfracture controls. To quantify vertebral bone marrow fat content and composition, patients underwent MR spectroscopy (MRS) of the lumbar spine at 3 Tesla. Bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine (LS) and quantitative computed tomography (QCT) of the LS. To evaluate associations of vertebral marrow fat content and composition with spinal and/or peripheral fragility fractures and diabetes, we used linear regression models adjusted for age, race, and spine volumetric bone mineral density (vBMD) by QCT. At the LS, nondiabetic and diabetic fracture patients had lower vBMD than controls and diabetics without fractures (p = 0.018; p = 0.005). However, areal bone mineral density (aBMD) by DXA did not differ between fracture and nonfracture patients. After adjustment for age, race, and spinal vBMD, the prevalence of fragility fractures was associated with -1.7% lower unsaturation levels (confidence interval [CI] -2.8% to -0.5%, p = 0.005) and +2.9% higher saturation levels (CI 0.5% to 5.3%, p = 0.017). Diabetes was associated with -1.3% (CI -2.3% to -0.2%, p = 0.018) lower unsaturation and +3.3% (CI 1.1% to 5.4%, p = 0.004) higher saturation levels. Diabetics with fractures had the lowest marrow unsaturation and highest saturation. There were no associations of marrow fat content with diabetes or fracture. Our results suggest that altered bone marrow fat composition is linked with fragility fractures and diabetes. MRS of spinal bone marrow fat may therefore serve as a novel tool for BMD-independent fracture risk assessment.
这项磁共振（MR）成像研究的目的是定量测定糖尿病和非糖尿病绝经后脆性骨折妇女的椎骨骨髓脂肪含量和组成，并将其与伴有和不伴有 2 型糖尿病的非骨折对照进行比较。招募了 69 名绝经后妇女（平均年龄 63±5 岁）。36 例患者（47.8%）有脊柱和/或外周脆性骨折。17 例骨折患者为糖尿病患者。33 名妇女（52.2%）为非骨折对照组。16 名妇女为非骨折糖尿病对照组。为了定量测定椎骨骨髓脂肪含量和组成，患者在 3T 磁共振上进行了脊柱磁共振波谱（MRS）检查。通过双能 X 线吸收法（DXA）测定髋部和腰椎（LS）的骨矿物质密度（BMD），通过定量计算机断层扫描（QCT）测定 LS 的骨矿物质密度。为了评估椎体骨髓脂肪含量和组成与脊柱和/或外周脆性骨折和糖尿病的关系，我们使用线性回归模型，通过 QCT 调整年龄、种族和脊柱体积骨矿物质密度（vBMD）进行校正。在 LS 处，非糖尿病和糖尿病骨折患者的 vBMD 低于对照组和无骨折的糖尿病患者（p=0.018；p=0.005）。然而，DXA 测定的面积骨密度（aBMD）在骨折患者和非骨折患者之间没有差异。调整年龄、种族和脊柱 vBMD 后，脆性骨折的患病率与不饱和水平降低 1.7%（置信区间[CI] -2.8%至-0.5%，p=0.005）和饱和水平升高 2.9%（CI 0.5%至 5.3%，p=0.017）相关。糖尿病与不饱和水平降低 1.3%（CI -2.3%至-0.2%，p=0.018）和饱和水平升高 3.3%（CI 1.1%至 5.4%，p=0.004）相关。有骨折的糖尿病患者骨髓不饱和程度最低，饱和程度最高。骨髓脂肪含量与糖尿病或骨折无相关性。我们的结果表明，骨髓脂肪组成的改变与脆性骨折和糖尿病有关。因此，脊髓骨髓脂肪的 MRS 可能成为一种新的、与骨密度无关的骨折风险评估工具。
