致密性乳腺1.5T磁共振DWI时b值的选择

Selection of b value in 1.5T DWI of dense breast

目的探讨致密性乳腺1.5T磁共振DWI时b值的选择。方法选取2019年1月~2020年1月于本院就诊的致密性乳腺女性患者64例,采集T2和DWI序列,弥散敏感因子b值分别取600 s/mm^(2)、800 s/mm^(2)、1200 s/mm^(2),对比不同b值下的图像信号强度比(SIR)、对比噪声比(CNR)、表观弥散系数(ADC)及对病灶与周围乳腺组织边界的显示情况,以病理结果为诊断金标准,计算诊断的敏感性、特异性、准确率。结果64例经临床相关检查共计发现病灶89个,MRI检出病灶83个,检出率93.25%,远高于乳腺X线摄影(46.06%),b值分别取600 s/mm^(2)、800 s/mm^(2)时的SIR、CNR高于b值取1200 s/mm^(2)组,b值取800 s/mm^(2)、1200 s/mm^(2)时对边界的判读优于b值取600 s/mm^(2)组。随b值的上升,周围乳腺组织、良恶性病灶的ADC值均下降,对于同一病灶,与周围乳腺组织相比,病灶的ΔADC在不同组间差异无统计学意义,b值取800 s/mm^(2)、1200 s/mm^(2)时的敏感性和准确性高于600 s/mm^(2)组,组间特异性均差异无统计学意义。结论1.5T磁共振DWI可以作为致密性乳腺筛查的有力补充手段,综合图像质量和诊断效能的考量,b值取800 s/mm^(2)较为合适。

Objective To investigate the selection of b value in 1.5T DWI of dense breast methods.Methods 64 females with dense breast underwent T2 and DWI MRI in our hospital from January 2019 to January 2020,the b value was taken as 600 s/mm^(2),800 s/mm^(2),1200 s/mm^(2).SIR,CNR,ADC and the display of the border between the lesion and the surrounding breast tissue were taken into account.Using pathological results as the gold standard,sensitivity,specificity and accuracy were calculated.Results A total of 89 lesions were found,and 83 cases were detected by MR.The detection rate was 93.25%,which was much higher than the mammogram(46.06%).When the b value was 600 s/mm^(2)and 800 s/mm^(2),the SIR and CNR were higher than 1200 s/mm^(2).When b was 800 s/mm^(2)and 1200 s/mm^(2),the interpretation of the boundary was better than b value 600 s/mm^(2).With the increase of b value,the ADC value of surrounding breast tissue and benign and malignant lesions decreased.For the same lesion,compared with the surrounding breast tissue,theΔADC of the lesion was not significantly different between different groups.The sensitivity and accuracy at 800 s/mm^(2)and 1200 s/mm^(2)group were higher than that of the 600 s/mm^(2)group,and there was no significant difference in specificity between the groups.Conclusion 1.5 T magnetic resonance DWI imaging can be used as a powerful supplementary method for dense breast screening.By comprehensive consideration of image quality and diagnostic efficiency,b value of 800s/mm^(2)is more appropriate.