Artifacts in contrast-enhanced mammography: are there differences between vendors?

PURPOSE: Contrast-Enhanced Mammography (CEM) produces a dual-energy subtracted (DES) image that demonstrates iodine uptake (neovascularity) in breast tissue. We aim to review a range of artifacts on DES images produced using equipment from two different vendors and compare their incidence and subjective severity. METHODS: We retrospectively reviewed CEM studies performed between September 2013 and March 2017 using GE Senographe Essential (n = 100) and Hologic Selenia Dimensions (n = 100) equipment. Artifacts were categorized and graded in severity by a subspecialist breast radiologist and one of two medical imaging technologists in consensus. The incidence of artifacts between vendors was compared by calculating the relative risk, and the severity gradings were compared using a Wilcoxon rank-sum test. RESULTS: Elephant rind, corrugations and the black line on chest wall artifact were seen exclusively in Hologic images. Artifacts such as cloudy fat, negative rim around lesion and white line on pectoral muscle were seen in significantly more Hologic images (p < 0.05) whilst halo, ripple, skin line enhancement, black line on pectoral muscle, bright pectorals, chest wall high-lighting and air gap were seen in significantly more GE images (p < 0.05). The severity gradings for cloudy fat had a significantly higher mean rank in Hologic images (p < 0.001) whilst halo and ripple artifacts had a significantly higher mean rank in GE images (p < 0.001 and p = 0.028 respectively). CONCLUSION: The type, incidence and subjective severity of CEM-specific artifacts differ between vendors. Further research is needed, but differences in algorithms used to produce the DE image are postulated to be a significant contributor.

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 >15 mm 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 >10 mm was noted in up to 90% of the larger breasts. CONCLUSION: Fixed immobile objects in the breast can appear to move a distance of >15 mm 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.