Assessing how water moves through breast tissue may help reduce the number of false-positive findings that lead to breast biopsies among women undergoing dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

Although DCE-MRI has been shown to be useful in breast cancer detection and staging, the technique yields a substantial number of false-positive findings. In an effort to differentiate benign lesions from malignancies on DCE-MRI, Savannah C. Partridge, PhD, research associate professor at the Seattle Cancer Care Alliance at the University of Washington, Seattle, and colleagues employed diffusion-weighted imaging (DWI). DWI, which research indicates is a promising tool for distinguishing between benign and malignant breast tissue, is an MRI technique that calculates a measure of how water moves through tissue. This measure is known as the apparent diffusion coefficient, or ADC.

The investigators evaluated 175 nonmalignant breast lesions in 165 women, determining ADCs for each lesion. Ultimately, DWI successfully characterized as benign 46% (81) of nonmalignant breast lesions identified as false-positive findings on DCE-MRI. These lesions exhibited ADC values that registered higher than a predetermined threshold; a biopsy might not be required when ADCs fall above that threshold.

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“We were excited to see the number of false-positives that could be reduced through this approach,” commented Partridge in a statement issued by the Radiological Society of North America, publisher of the journal Radiology, in which the study findings appear. “DWI gives us extra microstructural information to distinguish among lesions. We can use ADC values to draw a cutoff above which we might not need to do a biopsy.”

The most prevalent lesion subtypes with mean ADCs above the threshold were fibroadenoma, focal fibrosis, normal tissue, apocrine metaplasia, usual ductal hyperplasia, and inflammation.

Lymph nodes exhibited the lowest mean ADC value of all nonmalignant lesions. High-risk lesions (atypical ductal hyperplasia and lobular neoplasia) showed significantly lower ADCs than did other benign lesions, and were the most common lesions with ADCs below the threshold.