Needle bevel geometry influences the flexural deflection magnitude in ultrasound-enhanced fine-needle biopsy

TL;DR

This study investigates how different needle bevel geometries affect flexural deflection and resonance, aiming to optimize ultrasound-enhanced biopsy techniques by understanding the mechanical behavior of needle tips.

Contribution

It provides new insights into the relationship between needle bevel geometry and its mechanical deflection characteristics in various media, informing improved biopsy needle design.

Findings

Bevel geometry significantly influences deflection efficiency.

Longer bevels show higher deflection in air and water.

Understanding these effects can improve biopsy needle performance.

Abstract

It has been recently demonstrated that use of ultrasound increases the tissue yield in ultrasound-enhanced fine-needle aspiration biopsy (USeFNAB) as compared to conventional fine-needle aspiration biopsy (FNAB). To date, the association between bevel geometry and needle tip action has not been widely explored. In this study, we studied the needle resonance characteristics and deflection magnitude of various needle bevel geometries with varying bevel lengths. With a conventional lancet, having a 3.9 mm long bevel, the tip deflection efficiency in air and water was 220 and 105 micrometres per Watt, respectively. This was higher in comparison to an axi-symmetric tip, having a bevel length of 4 mm, which achieved a deflection efficiency of 180 and 80 micrometres per Watt in air and water, respectively. This study emphasised the importance of relationship between flexural modulus of bevel geometry in the context of various insertion media and, thus, could provide understanding on approaches to control post-puncture cutting action by modifying the needle bevel geometry, essential for the USeFNAB application.