Ultrasound guided breast biopsy in augmented women: How can we reduce the risk of implant damage? Experimental evaluation of a new semi-automatic approach.

Purpose: To evaluate whether a new semi-automatic approach in tissue sampling can help to reduce the risk of implant damage in ultrasound guided breast biopsies of suspicious lesions in augmented women.

Material and methods: The disposable biopsy-system 'HistoCore' (BIP, Germany) allows two different approaches for tissue sampling: 'full-automatic' and 'semi-automatic' biopsy. Choosing the full-automatic presetting the biopsy needle has to be placed in front of a lesion prior to shooting into it, whereas the semi-automatic mode allows to drive the inner part of the needle (i.e. the harvesting-notch) into the target manually under sonographic control with the outer cutting-needle shot subsequently into the tissue. Therefore the needle's terminal position can be accurately defined in advance, while the full-automatic setting allows only a rough estimation of its final position.

Both techniques were compared in augmented breast phantoms (genuine breast implants covered with pork belly) with simulated ˜5 mm tumors (pickled peppercorns, mimicing sclerotic lesions and bacon bits, simulating soft tissue lesions) fixed in the deep subcutaneous layer with tight contact to the inlay-shell. N= 80 lesions were randomized to undergo either full-automatic (n= 39) or semi-automatic biopsy (n= 41).

Results: Implant damage occurred in 9/80 overall cases, with n= 7 cases in the full-automatic and n= 2 cases in the semi-automatic group. The number of samples needed until representative tissue was achieved was higher in the full-automatic collective (1.5 vs. 1.2). Distances from the lesions to the implant surface were significantly smaller in cases resulting in implant damage (1.4 vs. 2.0), with no case of implant damage for lesions > 2.3 mm distant from the implant's surface in full-automatic and > 0.6 mm in semi-automatic setting.

Conclusion: Semi-automatic breast biopsy allows manual placement of the needle within a lesion under sonographic control reducing the risk of injury of underlying silicon implants during the biopsy procedure.