How to Weed Out False Positives on Breast MRIs

The study was published on researchsquare.com as a preprint and has not yet been peer reviewed.

Key Takeaway

• On breast MRIs, oval/round masses, masses with T2 hyperintense enhancement, and non-mass lesions with homogeneous enhancement patterns are unlikely to be malignant and are more likely to yield false positive results.

Why This Matters

• Use of breast MRI as a screening tool is limited by the high rate of false positives.

• The current findings can help reduce this risk by identifying features associated with false positives.

• Foregoing biopsy when these features are present can reduce patient anxiety and save healthcare dollars.

Study Design

• The team correlated the MRI findings and pathology results of 219 women (median age, 49 years) who had undergone biopsy of lesions detected by MRI.

• MRI findings were reviewed by two breast-trained radiologists.

Key Results

• Indications for MRI included screening (48% of women), staging (29%), and surveillance after malignant lumpectomy (9%).

• MRI-guided biopsies were performed for 219 patients; 62.5% of lesions were benign, 19.6% were high-risk, and 18% were malignant.

• The rate of false positive findings was 82.2%.

• Malignant lesions were slightly more likely among older patients (odds ratio [OR], 1.05; P = .0015).

• Irregularly shaped masses vs oval/round ones were over 11 times more likely to be malignant (OR, 11.2; P = .015).

• There was a significantly greater likelihood of false positive results with T2-hyperintense masses (OR, 0.13, P = .024).

• For non-mass lesions, those showing enhancements with clumped/clustered ring patterns, in comparison with homogeneous patterns, were more than three times more likely to be malignant (OR, 3.22).

Limitations

• The study was retrospective.

• The classification of MRI features was subjective.

• Women were primarily at high risk for breast cancer.

Disclosures

• Study funding and investigator disclosures were not reported.

This is a summary of a preprint research study, "False-Positive Incidental Lesions Detected on Contrast-Enhanced Breast MRI: Clinical and Imaging Features," led by Afsaneh Alikhassi of the University of Toronto. The study has not been peer reviewed. The full text can be found at researchsquare.com.

M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who has worked for several major news outlets before joining Medscape and also an MIT Knight Science Journalism fellow. Email: aotto@mdedge.com.

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