Abstract: Background　Multiple myeloma（MM） is a malignant proliferative hematological disease with abnormal accumulation of monoclonal plasma cells.Bone damage is one of its clinically defined presentations，thus making it particularly important to evaluate the degree of bone damage.Given the fact that fatty tissue is an important component of bone marrow and abnormal bone marrow microenvironment plays an important role in the pathogenesis of MM，more and more attention has been paid to the role of bone marrow fat content in the pathogenesis of MM.So far，Dixon imaging has been employed to measure the change in fat fraction of vertebral bone marrow，which plays a key role in the development of MM and newly diagnosed MM（NDMM）.Objective　We aimed to explore the value of the fat fraction acquired by T1-weighted two-point Dixon technique in the diagnosis of NDMM.Methods　Thirty inpatients with a definite diagnosis of MM〔including 25 with NDMM，and 5 with monoclonal gammopathy of undetermined significance（MGUS）〕 and 20 health examinees were recruited from Beijing Chao-yang Hospital（West Branch） from July 2016 to December 2019.The average fat fraction of each vertebral body（L1-5） and the average vertebral fat fraction of NDMM and MGUS patients and healthy controls were obtained by T1-weighted two-point Dixon technique at 3.0T MRI（Siemens Germany）.ROC curve analysis was utilized to evaluate the diagnostic efficacy of fat fraction for NDMM.Results　Compared to MGUS patients and healthy controls，NDMM patients had less average fat fraction of each vertebral body（L1-5）（P<0.05）.They also had less average vertebral fat fraction（P<0.05）.ROC curve analysis showed that the area under the curve of fat fraction for the diagnosis of NDMM was 0.946〔95%CI（0.917，0.976）〕，with the optimal cut-off value of 59.35%，and 87.20% sensitivity and 96.00% specificity.Conclusion　The fat fraction of vertebral bone marrow measured by T1-weighted two-point Dixon technique at 3.0T MRI was significantly lower in NDMM patients，which may has a certain value for diagnosing NDMM.

Key words: Multiple myeloma, Magnetic resonance imaging, Two-point T1-weighted Dixon, Fat fraction, Adiposity, Diagnosis

摘要： 背景　多发性骨髓瘤（MM）是一种单克隆浆细胞异常聚集的恶性血液病，骨质损害是其定义性临床症状之一，因此骨质评价显得尤其重要。由于脂肪组织是骨髓的重要组成成分，且异常骨髓微环境在MM发病中起着重要作用，因而骨髓脂肪含量在MM发病中的作用逐渐受到重视。目前采用磁共振Dixon技术测量椎体骨髓脂肪含量百分比（FF）变化，其对于MM疾病演变和早期新诊断MM（NDMM）起到关键性作用。目的　探究磁共振两点T1加权Dixon技术所测FF对NDMM的诊断价值。方法　选取2016年7月—2019年12月在北京朝阳医院西院住院确诊的MM患者30例，将MM患者分成NDMM组25例和意义未明单克隆丙种球蛋白血症（MGUS）组5例，选取同期于本院体检的健康志愿者20例为健康对照组（HC组）。采用3.0T MRI（西门子 德国）两点T1加权Dixon技术分别测量NDMM组、MUGS组和HC组的L1~5各椎体FF以及各组的平均椎体FF。采用受试者工作特征曲线（ROC曲线）评估椎体FF对NDMM的诊断效能。结果　NDMM组L1~5各椎体FF均低于MGUS组和HC组（P<0.05）。NDMM组平均椎体FF低于HC组、MGUS组（P<0.05）。FF诊断NDMM的ROC曲线下面积（AUC）95%CI为0.946（0.917，0976），最佳截断值为59.35%，灵敏度和特异度分别为87.20%、96.00%。结论　NDMM组椎体骨髓FF明显低于MGUS组和HC组，Dixon所测腰椎椎体骨髓FF对于NDMM诊断具有一定的价值。

关键词: 多发性骨髓瘤, 磁共振成像, 两点式Dixon, 脂肪比, 体脂肪率, 诊断