An Accurate Needle Tip Detecting Method for Ultrasound-Guided Regional Anaesthesia at Various Driving Voltages and Insertion Angles

Ultrasound-guided regional anaesthesia is increasingly used, enabling surgery on conscious patients. The precise location of the needle tip is crucial to avoid nerve damage, which is the main limitation of ultrasound. While colour Doppler imaging has the potential to improve needle visibility, limitations exist, particularly the obscuring of the needle tip by the colour pixel. This study aimed to determine the optimal parameters for accurately localizing the needle tip pixel in colour Doppler ultrasound images, enhancing the precision of regional anaesthesia procedures and determining the best insertion angle and voltage. A needle actuation transducer with two PZT4 rings was affixed to a 21 g nerve block needle and tested in a 20% gelatin phantom. Image processing, carried out using Python, involved multiple insertion angles and voltage levels. The Robust Linear Regression model (RLM) was utilized for needle position determination, and statistical analysis was performed using SPSS. The result showed that the Fit Accuracy (R2) mean values ranged from 0.5731 to 0.9260 for angles of 30°, 45°, 60°, and 75°, and from 0.7083 to 0.8194 for voltage levels of B-Mode, 1, 3, 5, 7, and 9. The angle groups showed a significant difference in Fit Accuracy (F (3, 956) = 123.177, p <. 001), as did the voltage groups (F (5, 954) = 5.185, p <. 001). This research presents a valuable methodology for accurately identifying the needle tip pixel in colour Doppler ultrasound, offering potential implications for improving the precision of regional anaesthesia procedures.