Purpose: To determine the outcome of lesions detected on contrast-enhanced mammography (CEM) that underwent short-interval follow-up after negative breast magnetic resonance imaging (MRI).
Materials and Methods: HIPAA-compliant IRB approved retrospective review of CEM exams performed from 2014 to 2021 identified 78 patients who had incompletely characterized enhancement on CEM with no suspicious corresponding enhancement on subsequent breast MRI performed within 1 month of the CEM, followed by a short-term follow-up CEM performed within 7 months. Patients who had less than 1-year mammographic follow-up (n=5) or who are still undergoing short-interval follow-up CEM (n=2) were excluded. Medical records and imaging studies were reviewed to identify patient and lesion characteristics, and outcome data.
Results: 71 patients with 81 CEM-detected lesions underwent short-interval follow-up CEM (median 6.2 months, range 4.5-7.8 months) after MRI failed to identify a suspicious correlate. Of 81 lesions, 73 (90%) were non-mass enhancement and 8 (10%) were enhancing masses, with median size 0.7 cm (range 0.3-6.5 cm) on CEM. Only 2/81 (2.5%) lesions had a correlate on the low-energy images (asymmetries) and no sonographic correlate was identified for 75 lesions that had a same-day targeted ultrasound. MRI performed within 1 month (median 0.3 months, range 0-1.0 month) demonstrated no corresponding suspicious enhancement. Six-month follow-up CEM detected 1 cancer (1.2%), which was diagnosed on MRI-guided biopsy after a follow-up MRI was performed (invasive ductal carcinoma). An additional cancer was detected at 1-year follow-up CEM, which was diagnosed on stereotactic-guided biopsy (ductal carcinoma in situ). Clip position after biopsies correlated with the enhancement seen on the original CEM studies. The remaining 79 lesions were stable or resolved on follow-up CEM (median 19.8 months, range 5.0-72.7 months) and all patients had at least 1-year mammographic follow-up.
Conclusion: Early preliminary data suggest that short-term follow-up of CEM-detected lesions 6 months after a negative MRI might not be necessary given the low cancer detection rate (1.2%) observed in our small cohort.
Clinical Relevance Statement: For CEM-detected lesions without corresponding suspicious enhancement on MRI, short-interval follow-up CEM is prudent to confirm benignity. However, only 1 cancer (1.2%) was detected at 6-month follow-up in our small study, suggesting that follow-up CEM performed 1 year after MRI may be sufficient.
