• A Johnson.
• Med Phys. 2016 Jun 1; 43 (6): 3461.

PurposeThe objective of this research was to demonstrate accuracy of a real-time passive ultrasound magnetic needle guidance technology (NGT) and target localization algorithm using conventional anechogenic contact phantoms and a novel fluid-filled hyperechogenic phantom simulating nerve block technique.MethodsAccuracy (mm to phantom target) was assessed by observing 35 medical practitioners (16 anesthesiologists and 19 residents) performing 560 needle procedures in high-fidelity ex vivo porcine tissue phantoms. Each practitioner performed 8 tasks with GE Venue 50 magnetic NGT system with PinPoint GT (Bard Access Sys.) and 8 conventional echogenic needle (control) procedures under various conditions (#18/#22 needle gauge, IP/OOP approach, and hyperechogenic simulated block approach targets or anechogenic solid targets). Passes, user feedback, and ergonomics were also assessed.ResultsOverlaid visual aids produced in real time (<300 mS delay) by NGT enabled users to consistently perform with better accuracy than control echogenic needle guidance. Accuracy improved by 51.2% at 95% CI [29.8%, 66.7%] (P = 0.0008) among block approach phantoms and 51.4% at 95% CI [34.9%, 64.0%] (P < 0.0001) among placement phantoms. Further, inadvertent contact with targets was reduced by NGT visualizations versus controls in both anesthesiologists (0 vs. 8 contacts; accuracy 2.0±1.7 vs. 4.13±6.7 mm) and novice users (3 vs. 12 contacts; accuracy 2.2±2.3 vs. 2.9±3.7 mm), respectively. Among novice users, NGT visualizations notably reduced quality-compromising ergonomic observations compared to controls under equivalent conditions.ConclusionNGT systems employing magnetic field generation and electromagnetic sensors to track needle position and orientation relative to a sonoanatomical target within a magnetic field have the potential to enable greater accuracy for complex needle placements and reduce unintentional needle contact, particularly in novice users. Further, NGT visualizations of needle tip and projected trajectory contribute to positive ergonomics and reducing quality-compromising behaviors among operators, potentially reducing fatigue and needle progression error. This work was supported by funding provided by the GE Healthcare Ultrasound Business, Milwaukee, WI.© 2016 American Association of Physicists in Medicine.

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