MRI method ‘cuts breast cancer false‑positives’

By Ingrid Grasmo, medwireNews Reporter

Assessing apparent diffusion coefficients (ADCs) during dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) may reduce the number of avoidable false-positive breast cancer results and unnecessary biopsies, show findings published in Radiology.

Savannah Partridge (University of Washington School of Medicine, Seattle, USA) and co-authors say the technique could also help improve patient management by differentiating high-risk lesions requiring additional workup from other nonmalignant subtypes.

The reduction in false-positive results is achieved through the use of diffusion-weighted imaging (DWI), an MRI technique that calculates the ADC for the targeted region.

"DWI has been used mostly in neurological applications, but it's been studied more recently in breast imaging," said Partridge in a press release. "It only adds a couple of minutes to the MRI exam and does not require additional contrast or any extra hardware."

Despite research showing that DWI is a promising tool for distinguishing benign from malignant breast cancers, little is known about the ADC values of specific subtypes of nonmalignant lesions.

For the study, the team performed a retrospective evaluation of nonmalignant lesions identified by DCE-MRI from 165 high-risk women, and then compared the ADCs from DWI for each lesion according to clinical subtype.

Findings revealed that 46% of lesions showed ADCs greater than the threshold of 1.81x10^-3 mm²/sec, with the most prevalent lesion subtypes including fibroadenoma (63%; 1.91x10^-3 mm²/sec), focal fibrosis (53%; 1.84x10^-3 mm²/sec), and adenosis (52%; 2.01x10^-3 mm²/sec).

By contrast, atypical ductal hyperplasia was the most common lesion subtype with ADC below the threshold (78%; 1.48x10^-3 mm²/sec), while lymph nodes exhibited the lowest average ADC of all nonmalignant lesion subtypes, at 1.28x10^-3 mm²/sec.

The researchers say that this finding confirms results from previous research suggesting that these two lesion types frequently show restricted diffusion.

High-risk lesions, such as atypical ductal hyperplasia and lobular neoplasia, showed significantly lower ADCs than other benign lesions and were the most commonly occurring lesions with ADCs below the threshold.

"The below-threshold ADCs of most high-risk lesions are not surprising owing to their histologic similarity to malignant lesions," say the researchers.

The team is planning a multicenter trial to validate the findings and determine how to incorporate ADC measures into clinical breast MRI interpretations. "We are very motivated to translate this promising technology to a clinically useful breast imaging tool," said Partridge.

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