2020 Volume 29 Issue 1 Pages 61-67
During stereotactic vacuum―assisted breast biopsy (ST―VAB), a marker is placed at the site of microcalcifications in order to indicate the target position. However, there are cases where the marker placed during the biopsy moves from the target position. Therefore, we defined the posterior nipple line (PNL) as the reference line on mammographic images and examined the evaluation method and factors involved in marker movement. From August 2016 to August 2018, markers were placed during ST―VAB, followed by mammography (MMG) in 41 women was taken. Among the 41 cases, marker migration by less than 20 mm was observed in 80% cases, by less than 20―30 mm in 5% cases, and by 30 mm or more in 15% cases. In the evaluation of the influence of the insertion direction, marker movements were more frequently observed in the lateromedial oblique projection (LMO), lateromedial projection (LM), inferomedial to superolateral oblique projection (ISO), with a tendency for the marker to move forward in the insertion direction. Markers showing a large degree of migration were pushed out from the tip of the opening and migrated in front, and then moved further due to the accordion effect after relieving the pressure. There was a significant difference in the degree of marker movement between the insertion direction ISO and other insertion directions. This is thought to be mainly attributable to the accordion effect and the rolling effect, wherein the mammary gland is rotated to bring out the chest wall during positioning. Evaluation using the PNL as reference suggested that the marker movement is influenced by the insertion direction.
