BACKGROUND

In the United States and Europe, MR-guided vacuum-assisted biopsy (VAB) is required for MR-only visible suspicious lesions that cannot be identified with mammography or ultrasonography. However, it is controversial as to whether MR-guided VAB is essential or not in Japan. The purpose of this study was to clarify the frequency of malignancy among the patients that underwent MR-guided VAB, and to discuss the need for this technique in Japan.

METHODS

This study was approved by the Institutional Review Board of our hospital. A retrospective review was performed of 30 consecutive patients who had undergone MR-guided 11-gauge VAB. The biopsies were performed on a 1.5 T MR scanner using a commercially available biopsy system. All lesions seen with MRI could not be detected by mammography and second-look ultrasonography.

RESULTS

All 30 lesions were assessed as category 4 or 5. The average lesion size of a mass enhancement before biopsy was 0.7 cm, and the average lesion size of a non-mass-like enhancement was 2.3 cm. The average number of cores of VAB was 19. The median time required to perform the VAB procedure was 35 min. The biopsy was successfully performed without important side effects in all patients. Histopathological findings were invasive ductal carcinoma in one (3%); ductal carcinoma in situ (DCIS) in seven (23%); and benign in 22 (73%). In one case, atypical ductal hyperplasia at VAB was upgraded to DCIS at surgical excision.

CONCLUSION

MR-guided VAB can be performed safely and it is needed for MR-only visible suspicious lesions in Japan.