Metallic marker placement after stereotactic core biopsy of breast calcifications: comparison of two clips and deployment techniques

OBJECTIVE: Two methods of deployment of metallic clips at the site of stereotactic core biopsy for breast calcifications are compared retrospectively. MATERIALS AND METHODS: One hundred nineteen clips deployed through an 11-gauge vacuum-assisted biopsy probe at core biopsy sites were compared with 109 vascular ligating clips deployed at biopsy sites using an 18-gauge spinal needle. The distance of each clip from the position of the target calcification was assessed using stereotactic coordinates in 52 sequential cases and was measured on mammograms before and after biopsy in 108 clips deployed through an 11-gauge probe and 98 clips deployed using an 18-gauge needle. Variance in clip position between postbiopsy and follow-up mammograms was measured in 43 clips placed with an 11-gauge probe and in 44 clips placed with an 18-gauge needle. Comparable measurements of variance in position of fat necrosis calcifications between screening mammograms were used as controls. RESULTS: Ninety-seven percent of the clips placed with an 11-gauge probe and 98% of the clips placed using an 18-gauge needle were within 1 cm of the target calcifications using stereotactic coordinates. On mammograms obtained after biopsy, 70% of the clips placed with an 11-gauge probe and 63% of the clips placed using an 18-gauge needle were within 1 cm of the target calcifications, and the position of 91% of the clips placed with an 11-gauge probe and 90% of the clips placed using an 18-gauge needle varied less than 15 mm on follow-up mammograms. Both clips provided accurate targets for wire-localized excisions. The cost of the 11-gauge needle and clip is $320. The 14-gauge probe, vascular clip, and 18-gauge spinal needle cost $191.58. CONCLUSION: A vascular ligating clip delivered to a stereotactic core biopsy site by an 18-gauge spinal needle is comparable in apparent accuracy and stability to a clip deployed through an 11-gauge probe. This technique allows core biopsies to be performed with instruments smaller than 11-gauge and at a 40% savings in equipment cost.