Susan Pae Weinstein MD, Presenter: Stockholder, Hologic, Inc

Lucy Hanna MS, Abstract Co-Author: Nothing to Disclose

Constantine Gatsonis PhD, Abstract Co-Author: Consultant, WILEX AG

Mitchell Dennis Schnall MD, PhD, Abstract Co-Author: Research funded, Siemens Consultant, General Electric Company

Mark Alan Rosen MD, PhD, Abstract Co-Author: Nothing to Disclose

Constance D. Lehman MD, PhD, Abstract Co-Author: Speaker, General Electric Company

To determine the frequency of malignancy in probably benign lesions seen on magnetic resonance imaging (MRI) in high risk screening patients enrolled in the American College of Radiology Imaging Network (ACRIN) study of screening the contralateral breast in women with a recent diagnosis of breast cancer.

ACRIN sponsored a prospective multi-institutional MRI screening trial (ACRIN 6667) of the contralateral breast in women recently diagnosed with breast cancer from 4/03 to 6/04. At enrollment, all women had negative clinical breast examinations and negative mammograms of the study breast. The radiologists utilized the American College of Radiology MRI Breast Imaging Reporting and Data System (BI-RADS) lexicon at image interpretation. Of the 969 women who constituted the final study group, 106 women were assigned a MRI detected BI-RADS category 3 lesion as their highest scoring lesion.

The 106 BI-RADS category 3 lesions were: 21 (19.8%) masses, 38 (35.8%) areas of non-mass enhancement (NME), 30 (28.3%) foci of enhancement (FE), 3 (2.8%) mass with FE, 6 (5.7%) mass with NME, and 6 (5.7%) FE with NME. Two cases reported no findings (1.9%). 83/106 (78.3%) patients had no evidence of malignancy in the study breast after 2 years of follow-up. The remaining 23/106 (21.7%) patients had tissue diagnosis. 17/106 (16.0%) patients elected to have biopsy. Biopsy was recommended for the remaining 6/106 (5.7%) patients based on follow up imaging findings. The patients underwent the following procedures: mastectomies (8), excisional biopsies (4), core needle biopsies (9) and fine needle aspirations (2). The biopsy results were: 18/23 (78.3%) benign, 2/23 (8.7%) atypical ductal hyperplasia, 2/23 (8.7%) atypical lobular hyperplasia and 1/23 (4.3%) DCIS. Overall, 1/106 (0.9%) case was diagnosed with malignancy among cases assigned BI-RADS 3.

The frequency of subsequent malignancy diagnosed in MRI BI-RADS category 3 lesions is similar to that seen in mammographic BI-RADS category 3 lesions.

In a multi institutional study, the frequency of malignancy in MRI detected BI-RADS category 3 lesions was shown to be similar to the accepted levels in mammographic BI-RADS 3 lesions.

Weinstein, S, Hanna, L, Gatsonis, C, Schnall, M, Rosen, M, Lehman, C, Frequency of Malignancy in Probably Benign Lesions Seen on Contrast-enhanced Breast MRI.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5014207.html