Position of clip placement after vacuum-assisted breast biopsy: is a unilateral two-view postbiopsy mammogram...

The objective of this study was to compare the accuracy of current methods of determining clip location (immediate stereotactic images versus postprocedure two-view mammograms) after stereotactic-guided, vacuum-assisted breast biopsy (VABB). Retrospective review was made of 101 lesions for which a localizing clip was placed during stereotactic VABB. Clip-to-lesion distances were measured by 1) stereotactic images (x, y, and z coordinates), and 2) postbiopsy two-view mammograms compared to prebiopsy two-view mammograms. The mean clip-to-lesion distance was 5.7 mm from stereotactic images, while the mean clip-to-lesion distances were 3.6 and 9.4 mm from same-view and orthogonal-view mammogram measurements, respectively. Stereotactic coordinate measurements compared to orthogonal-view mammogram clip-to-lesion measurements showed a significant difference (p < 0.001), as did the same-view mammogram compared to both stereotactic images and orthogonal-view mammogram (p < 0.001). The number of clips found to be less than 20 mm from the lesion (defined as clinically significant) was significantly higher for measurements from orthogonal-view mammograms (n = 19) compared to both stereotactic images (n = 0) and same-view mammograms (n = 5) (p < 0.001). Determination of clip location based on stereotactic images significantly underestimated the clip-to-lesion distance. Stereotactic images obtained at the conclusion of clip placement during VABB are not reliable in determining clip location relative to the targeted lesion. Although stereotactic images can confirm deployment of the clip, a two-view postbiopsy mammogram is necessary to determine clip location relative to the targeted lesion.