Displacement of breast tissue and needle deviations during stereotactic procedures

RATIONALE AND OBJECTIVES. The aim of this study was to quantify the displacement 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 coordinates of identifiable microcalcifications in the images before (baseline) and after needle positioning were analyzed (n = 52), For accuracy of needle positioning, differences between the coordinates of the needle tip and the target were analyzed in breast tissue (n = 97) and in air (n = 246), RESULTS. Average target displacement was 2.1 mm for biopsy needles (95% prediction 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 needles, respectively. CONCLUSIONS, Tissue and needle displacements cause a total positioning error of 2.4 mm in stereotactic core biopsy, which will limit the attainable diagnostic accuracy.