Is MRI suitable for conclusive work-up of suspicious findings in mammography and ultrasound?

Abstract

3 Background: The current ACR practice guidelines discourage use of MRI for work-up of suspicious findings in mammography (Mx) and ultrasound (US). We investigated whether additional breast MRI assessment of suspicious Mx and U.S. findings could improve PPV and thus possibly help reduce the number of biopsies for false positive findings in Mx or U.S. Methods: Between 06/2010 and 04/2012, a total 2,754 patients underwent DCE breast MRI. Of these, 277 underwent MRI for further work-up of suspicious findings made in Mx (n=173, 57 patients with mass lesions, 33 with asymmetries, 12 with architectural distortions, and 71 with suspicious calcifications) or U.S. (n=104, 74 with masses, 30 with miscellaneous U.S. findings such as suspected intraductal pathology, focal acoustic shadowing or architectural distortions) . All lesions categorized as MR-BIRADS 4 and 5 underwent biopsy, lesions categorized as MR-BIRADS 1 or 2 did not proceed to biopsy, except for selected women with mammographic calcifications suggestive of DCIS. Lesions categorized as MR-BIRADS 3 underwent additional short term follow-up by MRI, US and/or Mx. All women who did not undergo biopsy (MR-BIRADS 1-3) underwent long term follow-up for so far 12-24 months. Results: For suspicious lesions in mammography, MRI increased PPV from 19.3% (11/57) to 92.3% (12/13) for masses, from 3% (1/33) to 33.3% (1/3) for asymmetries, from 8.3% (1/12) to 25% (1/4) for architectural distortions and from 21.1% (15/71) to 62.5% (15/24) for calcifications. For suspicious lesions in ultrasound, MRI increased PPV from 13.5% (10/74) to 71.4% (10/14) for masses and from 3.3% (1/30) to 50% (1/2) for non-mass U.S. findings. In 4/277 patients, MRI showed additional suspicious findings, requiring MR-guided biopsy, one of which was histologically proven malignant. So far, none of the patients who, because of an MR-BIRADS 1-3, did not undergo biopsy has been diagnosed with invasive cancer or DCIS or with progressive conventional imaging findings necessitating secondary biopsy. Conclusions: MRI improves PPV for both suspicious Mx and U.S. findings, especially mass lesions. In experienced hands, careful use of MRI can help avoid biopsies for false positive diagnoses made in Mx and U.S.