Objective: To investigate the factors contributing to clip migration in stereotactic vacuum-assisted biopsy (VAB) of the breast using an upright unit with the patient in the decubitus position.
Methods: This retrospective study included 176 women with microcalcifications on mammograms undergoing stereotactic VAB with clip marking for analysis. The prebiopsy mammograms, stereotactic VAB images, immediate postbiopsy mammograms, and follow-up mammograms were reviewed. All VAB procedures were performed using an add-on upright unit with the patient in the decubitus position. The clip-to-lesion distance on the orthogonal view (craniocaudal view) on immediate postbiopsy mammography was estimated for each biopsy. Two cutoff points of clip-to-lesion distance of > 1 cm or > 2 cm were set for clip migration. The possible factors for clip migration based on clinical and imaging findings were then analyzed by Fisher's exact test.
Results: When the cutoff for clip migration was set at > 1 cm, thin breast (p = 0.013) and more superficial lesion (lesion closer to the skin along the line perpendicular to the posterior nipple line, p = 0.004) were associated with clip migration. When the cutoff was set at > 2 cm, thin breast (p = 0.019), high specimen number (p = 0.030), and posterior depth (p = 0.021) were associated with clip migration.
Conclusions: Thin breasts, superficial lesion location, posterior lesion depth, and high specimen number were the factors associated with clip migration.
Key points: • We reported clip migration after ST VAB using an upright unit with the patient in the decubitus position. • The occurrence of clinically significant clip migration (> 2 cm) in our study was 8.5%, which was within the range of the other reports with the patient undergoing ST VAB in the prone position. • Thin breasts, high specimen number, and more posterior depth were the factors associated with significant clip migration.
Keywords: Biopsy; Breast; Mammography; Stereotaxic techniques.