Stereotactic breast biopsy efficiency: Does a pre-biopsy grid image help?

Prior to stereotactic breast biopsy, some radiologists obtain a mammogram image with an overlying alphanumeric grid to mark the skin overlying the target. Our purpose is to determine if this grid image affects stereotactic biopsy efficiency and accuracy, including total images obtained, procedure time and need for retargeting.

IRB approved, HIPAA compliant retrospective review of prone stereotactic biopsy cases targeting calcifications 9/1/2015 to 9/1/2016 was performed. Images and reports were reviewed for number and type of images obtained, evidence of retargeting and biopsy table time. Attending radiologist, technologist and trainee involvement were recorded. Statistical analysis was performed utilizing SAS statistical software v 9.4 (SAS Institute, Cary, NC).

Of 463 women (avg age 58.0 years, range 30-94), 392/463 (84.7%) had grid images obtained pre-biopsy. Grid patients had more images total than non-grid (avg 9.26 versus 8.44 images/patient; p < 0.0001) but spent less time on the biopsy table (avg 15 min 2 s versus 16 min 44 s/procedure; p < 0.0001). Non-grid patients were more likely to undergo initial retargeting (45% non-grid vs 30% of grid patients; p = 0.013); however, later retargeting after needle placement was comparable (p = 0.3).

Grid imaging increases images obtained but decreases retargeting and biopsy table time at the expense of mammogram room/technologist time to obtain the grid image. The overall result is longer total procedure time (grid time plus table time) for the patient/technologist. A grid image therefore has limited usefulness and should be used judiciously in cases where prone positioning is challenging to patients.