Imaging Histologic Discordance at MRI-guided 9-gauge Vacuum-assisted Breast Biopsy

Objective: The purpose of this study was to determine the frequency of discordance at MRI-guided vacuum-assisted biopsy and to assess the cancer rate in discordant lesions.

Materials And Methods: With institutional review board approval, retrospective review was performed of a database of 342 lesions that had MRI-guided vacuum-assisted biopsy during a 39-month period. Biopsy samples were obtained in a 1.5-T magnet using a 9-gauge MRI-compatible vacuum-assisted biopsy device. Medical and pathology records were reviewed to determine the number of discordant lesions and surgical outcome. Statistical analysis was performed.

Results: Among 342 lesions that had MRI-guided vacuum-assisted biopsy, results were discordant in 24 (7% [95% CI, 3-14%]) lesions. The discordance rate was significantly (p < 0.001) higher among MRI target lesions that were possibly missed rather than sampled. A trend was seen (p < 0.06) toward a higher discordance rate in MRI lesions that were sampled rather than excised at MRI-guided vacuum-assisted biopsy. Subsequent surgery in 20 discordant lesions yielded cancer in six (30% [12-54%]), including ductal carcinoma in situ (DCIS) in two and invasive carcinoma in four (three ductal and one lobular, all with DCIS). The cancer rate among discordant lesions was significantly higher in postmenopausal women than in premenopausal women (p <0.05).

Conclusion: Imaging-histologic discordance was found in 7% of lesions that had MRI-guided vacuum-assisted biopsy. Among discordant lesions, surgical excision revealed cancer in 30%. Imaging-histologic correlation is essential after MRI-guided vacuum-assisted biopsy to avoid delay in the diagnosis of breast cancer.