Tissue bulge during stereotactic core biopsy

In full field digital mammography (FFDM) the whole breast is subjected to compression with a perspex compression paddle in order to reduce breast thickness and improve image quality. Once a mammographic abnormality has been detected using FFDM and a decision to proceed with a stereotactic (X-ray) guided core biopsy has been made, a different compression paddle is utilised. This paddle has a central aperture in order to allow access to the lesion for biopsy. Clinical observations made during biopsy procedures have revealed that a bulge of tissue forms within the aperture. The magnitude of the bulge of tissue and BI-RAD breast density was recorded in 15 consecutive patients. Results showed an average of 18.7% (range 11.3e30%) increase in the breast thickness (over the bulge region) compared to the surrounding compressed breast. BI-RAD breast density category 3 had on average the lowest measured thickness and the greatest percentage of tissue bulge. Overall, results confirm that for all patients there was a measurable tissue bulge that varied from 6 mm to 10 mm, representing between 10.14% and 23.08% of additional tissue not measured by the machine. In clinical practice a perceivable difference in lesion visibility was subjectively indicated between the FFDM images and the stereotactic scout biopsy image. The suggested hypothesis from these observations is that there may be an association between the magnitude of the tissue bulge and the ability to accurately perceive certain lesions during stereotactic biopsy procedures. A phantom study is in progress to determine how lesion visibility varies with the amount of tissue bulge