Ji Xiaodong, Huang Wenyang, Dong Huazheng, Shen Zhiwei, Zheng Meizhu, Zou Dehui, Shen Wen, Xia Shuang
Radiology Department, First Central Clinical College, Tianjin Medical University, Tianjin, China.
Department of Radiology, Tianjin First Central Hospital, School of Medicine, Nankai University, Tianjin, China.
Quant Imaging Med Surg. 2021 Feb;11(2):641-651. doi: 10.21037/qims-20-289.
Multiple myeloma (MM) is a blood cancer caused by the unlimited proliferation of intramedullary plasma cells. The presence of focal lesions (FLs) is presumed to be a more relevant factor for patient outcomes and risk distribution than diffuse bone marrow signal abnormalities. Signal changes in these FLs also have a good correlation with prognosis. As the cell density increased, a lower apparent diffusion coefficient (ADC) value was found with the diffusion-weighted imaging (DWI) sequence. Therefore, whole-body magnetic resonance imaging (MRI) with DWI sequences is sensitive to cell density and viability and may be vital for disease detection and therapy response assessments. However, the correlation between the DWI signal and the degree of bone destruction and the proportion of bone marrow plasma cells (BMPC) was still unclear in patients with MM. Water-fat separation MRI is used mainly for evaluating liver and bone marrow fat quantification, and fat quantification in other diseases. Meanwhile, it is also possible to assess the extent of bone marrow invasion in medullary lesions. This study aimed to investigate the correlation between ADC values from whole-body DWI and water/fat MRI signals from T1-weighted water-fat separation in evaluating bone marrow infiltration in patients with MM.
The study included 35 patients with MM who underwent whole-body DWI and T1-weighted water-fat separation Dixon examinations before therapy. The ADC values, normalized fat signal intensity (nMfat), normalized water molecular signal intensity (nMwater), and normalized fat fraction (nFF) of the thoracolumbar spine was measured in FLs and the normal-appearing bone marrow (NABM). The differences in values were compared using the independent-samples -test. The correlation between ADC values and water-fat MRI signals was estimated using the Pearson or Spearman correlation test. The correlation between the MRI above parameters and proportions of BMPC was also explored.
Statistically significant differences were found between the mean ADC values in FLs and NABM (0.72 . 0.33 mm/s, P<0.0001). Significantly elevated nMwater values and decreased nMfat and nFF values were observed in FLs; no correlations were found in NABM (P>0.05). The ADC value highly correlated with nMfat and nFF values and moderately with the nMwater value in FLs (r=-0.899, -0.834, 0.642, respectively, P<0.0001). Correlations were also observed between the proportion of BMPC and MRI parameters in MM (r=0.984, 0.716, -0.938, and -0.905, respectively, P<0.05).
The ADC value combined with water-fat separation parameters could be used for evaluating thoracolumbar bone marrow infiltration in MM. All parameters correlated with the proportion of BMPC, which helped assess the early response in MM therapy.
多发性骨髓瘤（MM）是一种由髓内浆细胞无限增殖引起的血液癌症。与弥漫性骨髓信号异常相比，局灶性病变（FLs）的存在被认为是影响患者预后和风险分布的更相关因素。这些FLs中的信号变化也与预后有良好的相关性。随着细胞密度增加，在扩散加权成像（DWI）序列中发现表观扩散系数（ADC）值降低。因此，采用DWI序列的全身磁共振成像（MRI）对细胞密度和活力敏感，可能对疾病检测和治疗反应评估至关重要。然而，MM患者中DWI信号与骨质破坏程度及骨髓浆细胞（BMPC）比例之间的相关性仍不明确。水脂分离MRI主要用于评估肝脏和骨髓脂肪定量以及其他疾病中的脂肪定量。同时，它也能够评估髓内病变中骨髓浸润的程度。本研究旨在探讨全身DWI的ADC值与T1加权水脂分离的水/脂MRI信号之间的相关性，以评估MM患者的骨髓浸润情况。
本研究纳入了35例在治疗前接受全身DWI和T1加权水脂分离狄克逊检查的MM患者。在FLs和外观正常的骨髓（NABM）中测量胸腰椎的ADC值、归一化脂肪信号强度（nMfat）、归一化水分子信号强度（nMwater）和归一化脂肪分数（nFF）。使用独立样本t检验比较各值的差异。采用Pearson或Spearman相关检验估计ADC值与水脂MRI信号之间的相关性。还探讨了上述MRI参数与BMPC比例之间的相关性。
FLs和NABM中的平均ADC值之间存在统计学显著差异（0.72±0.33 mm²/s，P<0.0001）。在FLs中观察到nMwater值显著升高，nMfat和nFF值降低；在NABM中未发现相关性（P>0.05）。在FLs中，ADC值与nMfat和nFF值高度相关，与nMwater值中度相关（分别为r=-0.899、-0.834、0.642，P<0.0001）。MM中BMPC比例与MRI参数之间也存在相关性（分别为r=0.984、0.716、-0.938和-0.905，P<0.05）。
ADC值结合水脂分离参数可用于评估MM患者的胸腰椎骨髓浸润情况。所有参数均与BMPC比例相关，这有助于评估MM治疗中的早期反应。
