Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine
【Purpose】 To evaluate the diagnostic effect of combined shear-wave elastography （SWE） and color Doppler US in addition to B-mode US in characterization of breast lesions and to know the factors need attention during the study of combination （color Doppler and SWE added on B-mode）. 【Materials and Methods】 From Jan 2011 to Dec 2013, 996 lesions （795 benign, 201 malignant） of 980 patients （mean age, 50.5） who underwent B-mode US and combined SWE and color Doppler US before biopsy were included. The size （<1cm, 1-<2cm, 2cm ≤） and BI-RADS assessment of B-mode US of each lesion were recorded. SWE with maximum visual color stiffness and vascular signal on Doppler US were retrospectively assessed. As for SWE, blue to green （≤80kPs） was used as benign reference point and as for color Doppler US, amount （≤3 vascular signals in or around lesion） or pattern （penetrating） were used to differentiate from malignant lesions. Diagnostic performance （sensitivity, specificity, PPV, NPV and diagnostic accuracy） of each B-mode, and combination modalities were statistically evaluated. And also that for only BI-RADS 4a lesions according to the lesion size were evaluated. 【Results】 Among 795 benign lesions, 337 fibroadenomas and 66 papillary lesions, 11 lesions with atypia and among 201 malignant lesions, 35 in situ carcinomas were enrolled. About 85 ％ of lesions were smaller than 2cm （T1） and B-mode assessment of the lesions met the likelihood of malignancy on BI-RADS system. The sensitivity and NPV of B-mode US were improved by adding color Doppler and SWE together （p<0.001）. The sensitivity, specificity, PPV, NPV and diagnostic accuracy of B-mode only and combination of color Doppler, SWE on B-mode are as follows; 83.6％, 93.2％, 75.7％, 95.7％ and 91.2％ for B-mode only, 90％, 72.6％, 45.4％, 96.6％ and 76.1％ for combination respectively. The lesion larger than 2cm in size, according to increased risk of cancer in benign pathology showed increased tendency of false positive and the lesion smaller than 1 cm in size, and DCIS, Non-ductal type cancer showed increased tendency of false negative, and BI-RADS 4b and 4c groups showed higher false positive and negative on combination study （p<0.01）. But for the category 4a only group, less than 2 cm, especially smaller than 1cm lesions showed high specificity and NPV （p<0.01）. 【Conclusion】 Color Doppler and SWE added to B-mode US revealed improvement of sensitivity and NPV, without improvement of specificity, PPV and diagnostic accuracy. But for the BI-RADS 4a lesions, the specificity and NPV are significantly higher on combination than color Doppler or SWE only added on B-mode. In combination study, we have to concern about the pathology, size and BI-RADS category.