Outcome of MRI-guided breast biopsy

The objective of our study was to investigate the outcome of MRI-guided breast biopsy as a function of the indication for MRI and the MRI features of the lesions.

In 154 women (mean age, 51 years) with 172 MRI-detected lesions, MRI-guided vacuum-assisted breast biopsy was attempted. Using the original radiologic report, we evaluated the indication for the original MRI examination and the MRI findings that led to biopsy. We investigated the core and operative histology results and follow-up data. We analyzed the cancer rate as a function of the indication for MRI and the MRI features of the lesions using Fisher's exact test.

In 22 of the 172 lesions (13%), MRI-guided biopsy was deferred due to decreased visualization or nonvisualization of the MRI finding that led to biopsy. Of 150 biopsies in 134 women, core histology revealed 39 malignant (39/150, 26%), 90 benign (90/150, 60%), and 21 high-risk (21/150, 14%) lesions. Through operative histology (n = 13) or follow-up (n = 30), four high-risk lesions were upgraded to malignancy and all deferred lesions except four lost to follow-up were confirmed to be benign. The final number of malignancies was 43 (29%) including 16 in situ and 27 invasive cancers. The probability of malignancy was different in the screening and diagnostic settings (14% vs 36%, respectively; p = 0.05), whereas it was not different according to lesion type (mass, 34%; nonmass, 27%; focus, 19%; p > 0.05) or kinetics (persistent, 23%; plateau, 31%; washout, 29%; p > 0.05).

The cancer rate in our cohort of women who underwent MRI-guided breast biopsy was 29%. It varied according to the indication for the original MRI examination, but not according to the MRI features of the lesions.