Design and Evaluation of Advanced Smart Needles for Brain Biopsy

Biopsy involves removing a piece of tissues for further medical examination. Brain biopsy is generally performed using different techniques, such as open biopsy, stereotactic core biopsy, and needle biopsy. Open biopsy is the most common and the most invasive form of the brain biopsy. During the procedure, a piece of the skull is removed and the brain is exposed. Stereotactic core and needle biopsies are minimally invasive. In these procedures, a hole is usually drilled into the skull and a needle is inserted through the hole to extract the tissue. Brain biopsy has its risks and complications due to the vulnerability of the brain tissue. Although using needle or stereotactic biopsies reduce the risks, brain biopsy may cause swelling or bleeding in the brain, and in some cases, can result in infection, stroke, seizure or even coma. A needle biopsy with conventional needles involves pulling or pushing the cutting stylet inside the needle hollow body (cannula). The manual pulling and pushing procedure induces lateral movement of the needle, which increases the damage in brain tissue. The goal here is to completely remove the needle harmful lateral movement. In this work, design of smart biopsy needles is proposed and demonstrated by incorporating nitinol wires and springs to control the lateral movement of the cutting stylet. The first design comprises of two parts. The first part of the needle is a 360° tissue cutting stylet, and the second part is the cannula. The cutting stylet can slide inside the cannula and a nitinol wire is embedded at the end of the stylet and the end of the cannula. As the electric current is applied on the nitinol wire, it shrinks and pulls the cutting stylet. The second design is almost similar to the first design, but it has a 180° tissue cutting stylet with a similar actuating mechanism. The last design uses a nitinol torsion spring that is attached to the cutting stylet. It cuts tissue samples by activating the nitinol spring to rotate the cutting stylet.