3.0T MRI多b值扩散加权平面回波成像对多发性骨髓瘤的诊断价值

目的 探讨应用3.0T磁共振（magnetic resonance，MR）扩散加权成像（diffusion-weighted image，DWI）对多发性骨髓瘤诊断的应用价值。方法 对50例临床确诊的多发性骨髓瘤（multiple myeloma，MM）患者及无骨髓病变的健康志愿者20例（>40岁），常规扫描后进行扩散加权成像扫描，取b值为0、50、600、1 000 s/mm²，分别测量健康组及MM病变骨髓信号强度比，用定性评分和定量计算信噪比（signal-to-noise ratio，SNR）的方法来比较不同b值DWI的图像质量，同时通过比较两组的ADC值以及不同b值的ADC值，确定敏感性诊断的最佳b值。结果 在常规T1WI及T2WI压脂序列上检出的164处病灶，在DWI上检出156处，敏感度达95%。在b值为50、600、1 000 s/mm²时，图像的信噪比SNR为22.28±14.40、11.85±7.78、7.57±4.72，各组间差异有统计学意义（F=19.523，P<0.05）；MM组ADC值分别为（1.52±0.81）×10^-3 mm²/s、（1.32±0.74）×10^-3 mm²/s、（1.11±0.71）×10^-3 mm²/s，b值为600及1 000 s/mm²组间，差异无统计学意义（P>0.05）；而b值为50及600 s/mm²组间差异有统计学意义（P<0.05），其ADC值随着b值的增高而减低；其敏感度随着b值的增高而增高，但信噪比明显降低，图像模糊，所测ADC值很不稳定。b为600 s/mm²，MM组与健康组ADC值分别为（1.32±0.74）×10^-3 mm²和（0.28±0.11）×10^-3 mm²，差异有统计学意义（P<0.01）。结论 3.0T MR DWI从分子水平定量的检出多发性骨髓瘤病变椎体的破坏程度，其检出率、敏感度较高，选择b值600测量数据较稳定，图像的信噪比较好。

Diagnostic value of 3.0T MRI multiple b value diffusion-weighted planar echo imaging for multiple myeloma

Objective To explore the optimal b value in diffusion-weighted 3.0T MRI scanning to diagnose multiple myeloma.Methods Fifty patients with multiple myeloma by clinical diagnostic criteria and twenty healthy volunteers were enrolled into this study. Following routine MRI scanning, sensitivity for diagnosis of multiple myeloma with different b values diffusion-weighted image (DWI) was 95% on 3.0-T MR unit. The image quality with different b values was analyzed and compared qualitatively by three scales system and quantitatively by signal-to-noise ratio (SNR). Apparent diffusion coefficient (ADC) between the MM group and the normal group was also measured.Results The smaller the b value was, the better the DWI image quality would be. Mean SNR of images obtained with b value 50, 600 and 1 000 s/mm² were 22.28±14.40,11.85±7.78,7.57±4.72 respectively. The difference among them was statistically significant (F=19.523, P<0.01) There was no significant difference between the mean ADC values on DWI with b value 600 s/mm²[(1.52±0.81)×10^-3 mm²/s] and 1000s/mm²[(1.32±0.74)×10^-3 mm²/s] (P>0.05). The mean ADC values of the normal volunteers group[(0.28±0.11)×10^-3 mm²/s] were significantly lower than that of the MM group[(1.32±0.74)×10^-3mm²/s] on DWI with b value 600 s/mm² (P<0.01).Conclusion A b value about 600 s/mm² is recommended when diffusion-weighted MRI scanning is used to diagnose multiple myeloma at 3.0 T MRI.