An Experimental Method of Needle Deflection and Prostate Movement Using the Anatomically Accurate Prostate Simulator and the Electromagnetic Tracking System

This study develops an experimental method to measure the needle deflection and prostate movement using an anatomically accurate prostate simulator with the electromagnetic tracking (EMT) system. Accurate needle insertion is crucial for prostate biopsy to acquire the tissue samples from cancer sites identified by magnetic resonance imaging. False negatives or inability to diagnose are the clinical challenges in the biopsy procedure. The main cause is that the needle tip missed the targeted cancer sites due to needle deflection and prostate movement. An anatomically accurate prostate simulator was developed to quantitatively and experimentally measure the deviation of needle tip from the ideal path and the movement of a target point in the prostate. The EMT system was utilized to simultaneously track the needle tip and target point positions in 3D space. Results show that the maximal needle deflection occurred at the first 60-mm insertion with 6.7 and 0.7 mm in and perpendicular to the needle insertion plane, respectively. The corresponding target point movements were 6.5 mm and 2.4 mm in and perpendicular to the needle insertion plane, respectively. Differences between multiple insertions through the same path have also been quantified. This method can be utilized to study clinical prostate biopsy techniques, evaluate the accuracy of needle devices, and train clinicians for accurate prostate needle biopsy.