Ultrasound Study For Breast Imaging Reporting And Data System Category4Microcalcifications On Mammography

ObjectiveTo evaluate the detection rate and image feature of ultrasound for BI-RADS (Breast imaging reporting and data system) category4microcalcifications without mass、facal dense or distortion on mammography,for better understanding the ultrasound image feature of microcalcifications,improving diagnostic rate of early breast cancer,and increasing opportunity of ultrasound guided biopsy,which is simple,comfortable and radiation reduced.Methods1.Sdudy populationBetween January2012and January2014,121patients with121breast calcified lesions which were found at Shenzhen Maternal and Children’s Hospital affiliated to South Medical University or other hospitals were included.Inclusive criteria:(1)microcalcifications without mass、facal dense or distortion,categorized as BI-RADS4on mammography.(2)lesions pathologically confirmed by core biopsy or surgical excision.(3)ultrasound was performed before surgery.(4) Specimen radiography was obtained after core biopsy or surgical excision to confirm the presence of microcalcifications.(5)No tissue biopsy,physical therapy,surgery or chemotherapy before.2. Equipments and methodsMammographic examinations were performed using digital mammography X-ray (Lorad Selenia) in our hospital. Standard craniocaudal(CC) and mediolateral oblique (MLO) views were obtained routinely, additional mammographic views were obtained when needed. Mammograms were assessed before biopsy by2-3radiologists with at least3years of experience. The number of microcalcifications in each group was categorized as fewer than10microcalcifications,10-30microcalcifications, or more than30microcalcifications. The breast parenchymal patterns、morphology and distribution of microcalcifications and final assessment category was determined according to BI-RADS.When there were more than one lesion in unilateral breast, the final assessment category was classificated according to the highest suspicious of malignancy.Breast ultrasound examinations were performed using8-14MHz linear array transducers and Acuson Sequoia512machine(Siemem). Patients were taken a supine position with the arms raised and both breasts and armpits were fully exposed, continous scanning was done in radial and antiradial planes. The areas that microcalcifications had been revealed on mammograms were carefully scanned. All images were interpreted before biopsy by one sonographer with at least10years of experience. The final assessment category was based on BI-RADS.The associated ultrasound findings at the area of microcalcifications were classified as follows:(1) negative;(2) only microcalcifications without associated findings;(3) microcalcifications within hypoechoic parenchymal thickening;(4) microcalcifications within solid-appearing distended duct;(5) microcalcifications within or adjacent to a mass;(6) cysts with calcifications.3. Biopsy Lesions prominently visible on ultrasound underwent ultrasound guided vacuum-assisted biopsy(VAB) or open surgical biopsy(OSB). Lesions not visible or uncertain on ultrasound underwent either X-ray guided stereotactic vacuum assisited breast biopsy(SVAB) or X-ray guided wire localization OSB. Specimen radiography was obtained after core biopsy or OSB to confirm the presence of microcalcifications.For those uncertain cases,postoperative ultrasound was done to analyze the surgical area.The pathological results was provided by the department of pathology in our hospital.4. Statistical AnalysesThe positive predictive values(PPV) of mammography and the sensitivity, specificity, PPV and negative predictive values(NPV) of ultrasound in diagnosing category4microcalcifications were evaluated.Differences in ultrasound detection rate of microcalcifications and in the ultrasound images findings between benign and malignant groups,and between DCIS and invasive carcinoma were analyzed using the chi-squared test, the Fisher’s exact test or the Mann-Whitney test.Differences with a p value of less than0.05were considered statistically significant. Statistical analyses were performed using a statistical software system (SPSS for Windows, version19.0).Results1. Biopsy59(48.8%) patients underwent ultrasound guided VAB or OSB and62(51.2%) underwent X-ray guided SVAB or mammographically guided wire localization OSB.2.Pathological results85cases(70.2%,85/121) pathologically confirmed to be benign and36cases (29.8%,36/121) confirmed to be malignant.3. BI-RADS comparison with pathological resultsThe PPV of mammography for microcalcification were29.8%(36/121).The sensitivity,specificity, PPV and NPV were61.1%(22/36),83.5%(71/85),61.1%(22/36),83.5%(71/85),respectively.4. Mammographic features of microcalcifications comparison with the ultrasound detection ratesAmong all lesions,the ultrasound detection rates of different shape were: pleomorphic(100%,5/5),coarse heterogeneous(71.4%,25/35),fine punctuate (62.9%,22/35), amorphous(47.8%,22/46),the differences were statistically significant (P<0.05).The ultrasound detection rates of different BI-RADS final assessment category were:4C(100%,6/6),4B(73.9%,17/23),4A(55.4%,51/92), the differences were statistically significant (P<0.05). The differences of ultrasound detection rates of different number and distribution of microcalcifications did not achieve statistical significance(P=0.115、0.141, respectively)Among all benign lesions,the differences of ultrasound detection rates of different number、shape、distribution and BI-RADS final assessment category did not achieve statistical significance(P=0.518、0.122、0.129、0.375, respectively)Among all malignant lesions,the differences of ultrasound detection rates of different number、shape、distribution and BI-RADS final assessment category did not achieve statistical significance(P=0.050、0.632、0.916、0.107, respectively)5. Pathological results comparison with the sonographic detection ratesThe overall ultrasound detection rate was61.2%(74/121). The detection rate of malignant lesions (77.8%,28/36) was significantly higher than benign lesions(54.1%,46/85)(P<0.05). The detection rate of invasive carcinoma (100%,8/8) was higher than DCIS(71.4%,20/28) but did not achieve statistical significance(P=0.086),the differences of ultrasound detection rates between different benign lesions did not achieve statistical significance(P=0.128)6.Ultrasound findings of lesions with different pathological results Among lesions showed microcalcifications within solid-appearing distended duct,the malignant lesions were significantly more than benign ones (P<0.05) and the DCIS were significantly more than IDC(P<0.05);Among lesions showed mass with microcalcifications,the malignant ones were significantly more than benign ones (P<0.05),and the IDC were significantly more than DCIS (P<0.05)Among lesions showed mass with microcalcifications,there were significant differences for shape and margin of the masses between benign and malignant lesions (P<0.05);Among lesions showed microcalcifications within hypoechoic parenchymal thickening,the area of the malignant lesions was significantly larger than that of benign ones (P<0.05)Conclusion1.US improves the PPV of the diagnosis of BI-RADS category4microcalcifications without mass、facal dense or distortion on mammography, which will avoid some unnecessary biopsies. Ultrasonic showing microcalcifications clearly could increase the opportunity of ultrasound guided biopsy,which has some advantages compared to X-ray-guided biopsy.2.Different mammographic features especially the shape and BI-RADS final assessment category of the microcalcifications could influence the detection rate of ultrasound for these lesions.3.Ultrasound helps to show the change of the mammary gland of the lesions apart from the microcalcifications,provides more information that will improve the diagnosis of the lesions.