Breast MRI proves helpful with inconclusive digital mammography, DBT results

Radiologists can feel confident turning to breast MRI in instances when digital mammography (DM) and digital breast tomosynthesis (DBT) results are inconclusive, according to new research published in the American Journal of Roentgenology.

“Although studies investigating MRI evaluation of equivocal DM findings have been previously published, to our knowledge no studies of MRI evaluation of equivocal DM/DBT findings exist.” wrote Bethany L. Niell, MD, PhD, department of radiology at Massachusetts General Hospital in Boston, and colleagues. “Therefore, the purpose of this study is to evaluate the utility of breast MRI as a problem-solving tool for equivocal findings identified on DM/DBT for women who also underwent diagnostic ultrasound.”

Niell and colleagues examined data from 67 breast MRI examinations performed from March 2011 to November 2014 to evaluate an inconclusive finding. All patients also underwent diagnostic ultrasound.

Overall, breast MRI examinations to further investigate inconclusive findings yielded a diagnosis of malignancy in seven percent of patients. It  had a positive predictive value of 19 percent and a negative predictive value (NPV) of 98 percent.

“Our results suggest that MRI is a useful adjunct modality with which to further evaluate the very small percentage of imaging findings that remain inconclusive despite thorough evaluation with mammography, DBT and ultrasound,” the authors wrote.

In addition, the team added, turning to breast MRI when these other modalities don’t tell a clear enough picture can directly lead to fewer unnecessary biopsies and help specialists make important decisions about the patient’s care.

“Breast MRI permits percutaneous biopsy of suspicious correlative findings identified on MRI and decreases the false-positive biopsy results that otherwise would have occurred if tissue sampling was initially recommended on the basis of the equivocal DM/DBT finding,” the authors wrote. “Given the relatively high NPV of MRI, a negative MRI result also provides reassurance to the radiologist and patient that short-term follow-up imaging of the equivocal DM/DBT finding would be a reasonable next step.”