Design of a novel miniature breast biopsy needle for ductoscopy

Background. The majority of the benign and malignant lesions in the breast arise from the ductal epithelium and terminal ductlobular unit. A minimally invasive procedure called ductoscopy is able to visualize these lesions as it inspects the ductal epithelium using a small micro-endoscope. Unfortunately, it is currently challenging to obtain a tissue sample during ductoscopy and reach the most distal duct. Methods. In this study we have, therefore, developed a novel miniature (∅1.2 mm) biopsy needle that can be used during ductoscopy. This biopsy needle consists of two coaxial counter-rotating hollow blades with a distal cutout to resect lesions from the ductal wall. Three cutouts were manufactured resulting in a beveled, straight, and reverse-beveled blade. The blades were actuated using a novel mechanism containing two helical paths that allows for the counter-rotating motion of the blades at different velocities. In a proof-of-principle experiment, the performance of the biopsy needle was evaluated using a polymeric duct model and gelatin tissue phantom. Results. During the experiment, the straight and reverse-beveled blades were able to obtain a sufficiently large tissue sample for histopathological examination. Based on these promising results, a second experiment was performed in which the micro-endoscope was integrated in the needle and we were able to take a biopsy from a chicken breast. Conclusions. In a future clinical instrument, the biopsy needle will be miniaturized and optimized to allow for an efficient, safe, and effective intraductal biopsy procedure without the need for an invasive excisional biopsy procedure.