Eugene Mun Wai Ong MBBS, FRCR, Presenter: Nothing to Disclose

Sughra Raza MD, Abstract Co-Author: Research grant, Hitachi, Ltd

Sona Ajit Chikarmane MD, Abstract Co-Author: Nothing to Disclose

Meera Sekar MD, Abstract Co-Author: Nothing to Disclose

Katrina L. Rabinovich MD, Abstract Co-Author: Nothing to Disclose

Robyn L. Birdwell MD, Abstract Co-Author: Nothing to Disclose

To explore morphology, enhancement and kinetic features of NMLE on breast MRI and to correlate these findings with pathology.

IRB approved review of 565 MR-guided breast biopsy cases from 3/04 -2/09 showed 215 cases prospectively reported as NMLE in 204 patients. Of these, 130 had core biopsy and 85 were surgically excised after wire localization. The diagnostic MR study prompting biopsy was retrospectively reviewed by 2 radiologists blinded to final pathology. Lesions were described using BI-RADS lexicon terms for morphology, kinetics and final assessment category.

Of 215 NMLE lesions, 159 (74.0%) were benign and 56 (26.6%) malignant. Of 56 malignancies, 26 (46.4%) were invasive and 30 (53.6%) were in situ carcinoma. Of the invasive cancers, 20/26 were small foci of invasion in extensive in situ carcinoma, 5 were invasive ductal or mixed ductal and lobular, 1 was lobular. Mean patient age for benign and malignant lesions was 48.3 and 55.8 years respectively (p<0.0001). There was no difference in mean size of malignant (3.0 cm) and benign NMLE (2.5cm) (p= 0.13), however lesions >4cm were more likely to be malignant (p=0.04). Most common distribution was ductal/linear (n=104, 48.4% of all NMLEs) with PPV of 26.9%. The most common internal enhancement patterns were clumped (n=93) and heterogeneous (n=80) accounting for 80.5% of all NMLE, with PPV of 28% each. For benign NMLE the most common distribution was focal area (80%) and most common internal enhancement pattern was homogeneous (88%). In 35 cases with NMLE ipsilateral to a recent breast cancer, 16 (45.7%) were malignant. A greater proportion of malignant NMLE was found in patients with ipsilateral breast cancer compared to all other patients (p=0.004). Enhancement kinetics of the 56 malignant NMLEs were persistent in 53.6%, plateau in 37.5% and washout in 8.9%, with no difference in proportion of malignancy based on kinetics (p=0.77).  

Higher patient age, lesion size >4cm and current ipsilateral breast cancer were statistically significant predictors of pathologic outcome. NMLE distribution, internal enhancement pattern and kinetics were not independently predictive of benign versus malignant outcome.

To our knowledge this study represents the largest reported series of NMLE on breast MRI with pathologic correlation, and therefore helps validate specific BI-RADS modifiers for such lesions.

Ong, E, Raza, S, Chikarmane, S, Sekar, M, Rabinovich, K, Birdwell, R, Nonmasslike Enhancement (NMLE) on Breast MRI: Correlating BIRADS-based Characterization with Pathology.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8004869.html