对比增强乳腺X线摄影灰度值定量测量鉴别诊断乳腺钙化良性与恶性的研究

Differential diagnosis of benign and malignant breast calcification by quantitative measurement of gray value on contrast-enhanced spectral mammography

目的探讨对比增强乳腺X线摄影(CESM)中减影图像灰度值(GV)测量对乳腺钙化病变良性与恶性的鉴别诊断价值。方法该研究为回顾性研究。收集2017年3月至2021年7月北京大学肿瘤医院因乳腺X线摄影检出以钙化为唯一可疑征象而接受CESM检查的连续性病例95例,均为女性,年龄34~76(48±7)岁。患者均接受头尾(CC)位及内外斜(MLO)位CESM。2名医师根据目标钙化剪影图像上有无强化作出良、恶性主观判断。另由2名医师在减影图像上分别测量MLO及CC位的钙化病变区GV,并以乳腺腺体、胸大肌、皮下脂肪等区域作为背景实质测量GV,计算病灶/背景灰度差值(DGV)及病灶/背景灰度差值比(DRGV)。以变异系数评价GV稳定性,以Kappa检验分析2名医师测量的一致性;以独立样本t检验或Mann-Whitney U检验比较良性与恶性钙化不同区域GV值的差异;以受试者操作特征曲线(ROC)分析GV鉴别钙化良性与恶性效能。诊断效能间的比较采用χ^(2)检验。结果纳入的95例患者中共97个钙化,其中良性62个,恶性35个。2名医师测量MLO及CC位钙化病变区GV值的一致性和稳定性均较高。恶性钙化病变区GV、DGV、DRGV均高于良性钙化(P<0.05)。MLO位和CC位钙化区域GV鉴别诊断良性与恶性钙化的ROC曲线下面积分别0.799、0.843,以CC位钙化区域GV=2015.5为阈值,其诊断准确度为76.8%,与有一定CESM阅片经验的医师主观判断的准确度(82.1%,78/95)差异无统计学意义(P>0.05)。结论CESM减影图像上进行钙化区域的GV测量可帮助鉴别乳腺钙化的良性与恶性,尤其CC位测量的诊断准确度高。

Objective To investigate the value of gray value(GV)measurement of subtraction images in contrast-enhanced spectral mammography(CESM)in the differential diagnosis of breast benign and malignant calcification.Methods This was a retrospective study.A total of 95 patients received CESM only with mammographic calcifications without any associated mass or distortions from March 2017 to July 2021 in Peking University Cancer Hospital were enrolled.The patients were all female with an average age of 34-76(48±7)years.The craniocaudal(CC)projection of bilateral breasts was obtained prior to the mediolateral-oblique(MLO)projection.Two radiologists were asked to independently review the images to diagnose the calcification as either benign or malignant based on the presence of enhancement on subtracted imaging.GV of the calcification and background parenchyma including breast parenchyma tissue,the pectoralis major muscle and subcutaneous fatty tissue were measured by another two radiologists.The difference of lesion to background parenchyma GV(DGV)and lesion to background parenchyma gray value ratio(DRGV)were calculated.The consistency of observers was compared using the Kappa statistic.The stability of GV was evaluated with coefficient of variation.Differences of GV,DGV and DRGV between benign and malignant calcification were compared using t test or Mann-Whitney U test.Receiver operating characteristic(ROC)curves were used to analyze the efficacy of GV in differentiating benign from malignant calcification.Comparisons between diagnostic efficacies were performed usingχ^(2)tests.Results Totally 97 calcification(35 malignant and 62 benign)from 95 patients were enrolled.The consistency and stability of GV values on MLO and CC projections measured by two physicians were high.The GV,DGV and DRGV of malignant calcification were significantly higher than those of the benign lesions(P<0.05).The area under the ROC curve for the differential diagnosis of benign and malignant calcification by GV in the MLO and CC positions was 0.799 and 0.843,respectively.Threshold of calcified area GV=2015.5 in CC position,its diagnostic accuracy was 76.8%,which was similar to the subjective diagnosis of radiologists(82.1%,78/95,P>0.05).Conclusion Quantitative GV on subtracted imaging of CESM can differentiate benign from malignant breast calcification,especially on craniocaudal projection.