Multi-Bevel Needle Design Enabling Accurate Insertion in Biopsy for Cancer Diagnosis

To obtain definitive cancer diagnosis for suspicious lesions, accurate needle deployment and adequate tissue sampling in needle biopsy are essential. However, the single-bevel needles in current biopsy devices often induce deflection during insertion, potentially causing lesion missampling/undersampling and cancer misdiagnosis. This study aims to reveal the biopsy needle design criteria enabling both low deflection and adequate tissue sampling.

A novel model capable of predicting needle deflection and tissue deformation was first established to understand needle-tissue interaction with different needle tip geometries. Experiments of needle deflection and ex-vivo tissue biopsy were conducted for model validation.

The developed model showed a reasonably good prediction on the correlation of needle tip type vs. the resultant needle deflection and tissue sampling length. A new multi-bevel needle with the tissue separation point below the needle groove face has demonstrated to be an effective design with an 87% reduction in deflection magnitude and equivalently long tissue sampling length compared to the current single-bevel needle.

This study has revealed two critical design criteria for biopsy needles: 1) multiple bevel faces at the needle tip can generate forces to balance bending moments during insertion to enable a low needle deflection and 2) the tissue separation point should be below the needle groove face to ensure long tissue sampling length.

The developed methodologies and findings in this study serve as proof-of-concept and can be utilized to investigate various biopsy procedures to improve cancer diagnostic accuracy as well as other procedures requiring accurate needle insertion.