Comparison Between Cone-beam Breast CT And Mammography In Evaluating Breast Coverage,Comfort And Accuracy Of Measurement

Objective:To compare the difference between cone beam beast CT(CBBCT)and mammography in breast coverage,comfort and the accuracy of measurement.Methods:1.199 patients(330 breasts)who underwent CBBCT and mammography from October,2012 to December,2013 were analyzed retrospectively.The superior,inferior,medial,lateral and posterior aspects coverage of breast tissue in both CBBCT and mammography were evaluated by two radiologists.The readers evaluated the superior,inferior,medial and lateral coverage of CBBCT in the sagittal and transverse images.The superior and inferior coverage of mammography were evaluated in MLO images,and the coverage of the medial and lateral were evaluated in CC images.Breast-tissue coverage was defined as positive if the curvature of the breast could be visualized in superior,inferior,medial,lateral regions,otherwise it was negative.The curvature was the connection curve between the breast tissue and the adjacent skin tissue.The posterior coverage of CBBCT was defined as positive if the pectoralis muscle could be visualized.If the the pectoralis muscle could be visualized in CC image,the posterior coverage of mammography was positive.The inter-reader agreement was analyzed by Kappa.Paired Chi-square was used to assess the differences in breast coverage between CBBCT and mammography.2.409 patients were included who performed CBBCT and MG in Tianjin Medical University Cancer Institute and Hospital and Sun Yat-sen University Cancer Center from October,2012to January,2014.Patients evaluated their comfort by using an 11-point numerical rating scale(NRS-11)after completing examinations.The score was from 0 to 10,using whole numbers.The lower the score was,the more comfortable the examination modality was.The data was divided into different subgroups according to CBBCT scan mode(non-contrast mode,contrast-enhanced mode),age(≤44,45～59 and≥60),body mass index(BMI)(<18.5kg/m~2,18.5～23.9 kg/m~2,24～27.9kg/m~2and≥28kg/m~2),breast density(fatty-breast,dense-breast).The paired rank sum test was used to compare the comfort between CBBCT and mammography.Chi-square test was used to evaluate the factors influencing of the comfort of CBBCT.3.76 patients confirmed by pathology were included from December,2012 to December,2014.They underwent mammography,ultrasonography and CBBCT examinations.The maximum diameter of tumor measured by three examination methods was recorded.The concordance of the maximum diameter of tumors between the three methods and pathology was evaluated whether the discrepancy was less than±0.5cm(including0.5cm).The interclass correlation coefficients(ICC)and Pearson correlation coefficient were used to evaluating the overall,benign tumor and malignant tumor concordance and correlation between three methods and pathology.Chi-square test was used to evaluate the accuracy of measurement among the three modalitys.Results:1.CBBCT had a statistically significant improvement in coverage compared to mammography in the inferior,medial,lateral,and posterior aspects(all P<0.05).Mammography had better coverage than CBBCT in the superior aspects(P<0.01).2.There was statistically difference between the score of CBBCT and the score of mammography.CBBCT was more comfortable than mammography.There was no statistically difference between the score of CBBCT and the score of mammography in≥60 group and<18.5 kg/m~2group.There was statistically difference in other subgroups(all P<0.05).The CBBCT scan mode,age and BMI of the patients could influence the comfort of CBBCT.3.Overall,the agreenment between CBBCT and pathology measurement was higher than mammography and ultrasonography based on ICC value and Person’s correlation coefficient.For benign tumor,the agreenment between ultrasonography and pathology measurement was lower than mammography and CBBCT.For malignant tumor,the agreenment between CBBCT and pathology measurement was higher than mammography and ultrasonography.The accuracy of CBBCT was higher than that of mammography.Conclusion:1.CBBCT has better breast tissue coverage than mammography in the inferior,medial,lateral,and posterior aspects,but the coverage in the superior aspect was lower than mammography.2.The comfort of CBBCT was better than that of mammography.Scan mode,age could influence the comfort of CBBCT.3.CBBCT can accurately measure the maximum diameter of breast tumors.