Radiographer technique: Does it contribute to the question of clip migration?

Introduction: Marker clips are commonly deployed at the site of a percutaneous breast biopsy. Studies have shown that displacement of the clip from the site of deployment is not uncommon. The objective of this study was to determine how much migration' could be seen with fixed structures within the breast tissue across three consecutive annual screening examinations, and therefore attempt to quantify how much of the reported clip migration could be due to radiographer technique. Methods: Large, easily identified benign calcifications were measured by two investigators across three consecutive cycles of screening mammography. The position of the calcifications on the two standard mammographic views was measured in two planes. Other variables recorded included breast size and density, compression force used, and location of the benign calcifications within the breast. Results: In 38% of cases, benign breast calcifications showed a mimicked movement of >15mm in at least one plane. This was greatest in large breasts, those where fibroglandular tissue occupied less than 50% of the breast volume, and in the upper outer quadrant of the breast where mimicked movement >10mm was noted in up to 90% of the larger breasts. Conclusion: Fixed immobile objects in the breast can appear to move a distance of >15mm in up to 30% of cases. Clinically, some of what has previously been called marker migration' may be spurious and accounted for by differences in radiographic positioning techniques.