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The purpose of this study was to investigate whether breast MRI can be used to rule out malignancy in patients with high-risk lesions diagnosed at imaging-guided core needle biopsy.The subjects were women consecutively registered between October 2004 and April 2010 who had high-risk lesions diagnosed at mammographically or sonographically guided core needle biopsy and subsequently underwent MRI and surgical excision. MR images were reviewed by two experienced breast radiologists. Lesions assessed as BI-RADS category 1-3 were considered negative for malignancy, and BI-RADS 4 and 5 lesions were considered malignant. Histologic findings at surgical excision were the reference standard. The sensitivity, specificity, and positive and negative predictive values of MRI in the detection of associated malignancy were calculated for the entire set of lesions and for each histologic subtype.The final sample consisted of 169 high-risk lesions in 166 patients. At MRI analysis, 116 (68.6%) lesions were considered negative for malignancy, and the other 53 (31.4%) malignant. At surgical excision, 22 malignant lesions were found. The overall sensitivity, specificity, and positive and negative predictive values of MRI were 72.7% (16/22), 74.8% (110/147), 30.2% (16/53), and 94.8% (110/116). The negative predictive values for papilloma, radial scar, lobular neoplasia, and atypical ductal hyperplasia were 97.4% (38/39), 97.6% (41/42), 88.0% (22/25), and 90.0% (9/10).Patients with high-risk lesions associated with the lowest likelihood of malignancy (papilloma and radial scar) and without suspicious MRI findings can safely undergo follow-up instead of surgery. Because of the low negative predictive value, however, MRI is not helpful in cases of lobular neoplasia and atypical ductal hyperplasia, and all these lesions should be excised.

The purposes of our study were, first, to evaluate the frequency, clinical presentation, and associated imaging findings of malignant breast lesions presenting as hyperechoic nodules in a large series of consecutive sonographically guided core needle biopsies (CNBs) and, second, to investigate sonographic features that are able to predict malignancy in hyperechoic breast lesions.The radiologic and pathologic records for 4511 consecutive sonographically guided CNBs were retrospectively reviewed. Hyperechoic lesions were identified, and clinical notes and related mammography or MRI reports were reviewed. The sonographic images were evaluated according to the BI-RADS lexicon by two experienced breast radiologists. Surgical pathology results and follow-up served as the reference standard for lesions diagnosed as malignant or high-risk and benign at CNB, respectively. The frequency of hyperechoic carcinomas among all carcinomas was calculated. Differences in sonographic appearance between hyperechoic benign and malignant lesions were evaluated using the chi-square test or the Fisher exact test.Of all biopsied lesions, 25 (0.6%) were hyperechoic. Among the 1849 malignant lesions, nine (0.4%) were hyperechoic. The remaining 16 were benign. None of the hyperechoic malignancies was a "purely" sonographic lesion, because all were palpable, mammographically visible, or detectable on breast MRI. Malignant lesions were more likely than benign lesions to have noncircumscribed margins (9/9 vs 7/16; p = 0.008) and nonparallel orientation (6/9 vs 1/16; p = 0.003).When encountering a hyperechoic nodule, malignant nature cannot be excluded. Suspicious sonographic signs and correlation with other imaging techniques may help avoid misdiagnosis.