Displacement of breast tissue and needle deviations during stereotactic procedures

RATIONALE AND OBJECTIVES. The aim of this study was to quantify the displac ement of breast tissue and the inaccuracy of needle positioning for biopsy (14-gauge) and localization (19.5-gauge) needles. METHODS. For displacement of breast tissue, differences between the coordin ates of identifiable microcalcifications in the images before (baseline) an d after needle positioning were analyzed (n = 52), For accuracy of needle p ositioning, differences between the coordinates of the needle tip and the t arget were analyzed in breast tissue (n = 97) and in air (n = 246), RESULTS. Average target displacement was 2.1 mm for biopsy needles (95% pre diction interval [PI] 0.6-7.8) and 1.0 mm (95% PI 0.3-3.9) for localization needles. Mean inaccuracy of needle positioning in breast tissue was 1.1 mm (95% PI 0.4-3.0) and 1.8 mm (95% PI 0.7-46) for biopsy and localization ne edles, respectively. CONCLUSIONS, Tissue and needle displacements cause a total positioning erro r of 2.4 mm in stereotactic core biopsy, which will limit the attainable di agnostic accuracy.