MR visible only lesions: what are the predictors for malignant outcome?

Introduction

To correlate pathological outcomes of MRI vacuum biopsies on MRI visible only breast lesions with lesion morphology, time-enhancement curves and clinical indications to determine the use of these as predictors for malignancy.

Methods

A retrospective analysis of 277 patients referred for MRI-guided vacuum biopsies of impalpable breast lesions visible only on MRI was performed. All patients had a minimum follow-up period of 11 months. MRI biopsies were undertaken on a 1.5 T magnet using a minimum of 12 passes of vacuum-assisted biopsies. The pathological findings were correlated against BI-RADS appearances and time-enhancement characteristic of the lesions and against the clinical indications for MRI examination.

Results

A total of 286 vacuum biopsies were undertaken. Eighty-one were malignant (28.3%), of which 72.8% are masses and 27.2% are nonmasses. Only two malignant lesions had a type 1 curve (2.5%), compared with malignant lesions with type 2 (54.3%) and type 3 curves (43.2%). Both malignant lesions with type 1 curve had a suspicious morphology. Nonmalignant lesions with type 3 enhancement included lymph nodes, fibroadenomatoid hyperplasia, papillary lesions, fibrocystic change and lobular neoplasia.

Conclusions

Lesion morphology and time-enhancement curves are useful predictors of malignancy and can be used to develop an algorithm to help direct appropriate biopsy of MRI-detected lesions. We recommend that in the absence of suspicious morphology, only lesions with type 2 and type 3 curves should be subjected to MRI-guided biopsy.