title: Ultrasound-Guided Needle Technique Accuracy: Prospective Comparison of Passive Magnetic Tracking Versus Unassisted Echogenic Needle Localization.
abstract: OBJECTIVE
  Ultrasound-guided regional anesthesia facilitates an approach to sensitive targets such as nerve clusters without contact or inadvertent puncture. We compared accuracy of needle placement with a novel passive magnetic ultrasound needle guidance technology (NGT) versus conventional ultrasound (CU) with echogenic needles.
  
  
  METHODS
  Sixteen anesthesiologists and 19 residents performed a series of 16 needle insertion tasks each, 8 using NGT (n = 280) and 8 using CU (n = 280), in high-fidelity porcine phantoms. Tasks were stratified based on aiming to contact (target-contact) or place in close proximity with (target-proximity) targets, needle gauge (no. 18/no. 22), and in-plane (IP) or out-of-plane (OOP) approach. Distance to the target, task completion by aim, number of passes, and number of tasks completed on the first pass were reported.
  
  
  RESULTS
  Needle guidance technology significantly improved distance, task completion, number of passes, and completion on the first pass compared with CU for both IP and OOP approaches (P ≤ 0.001). Average NGT distance to target was lower by 57.1% overall (n = 560, 1.5 ± 2.4 vs 3.5 ± 3.7 mm), 38.5% IP (n = 140, 1.6 ± 2.6 vs 2.6 ± 2.8 mm), and 68.2% OOP (n = 140, 1.4 ± 2.2 vs 4.4 ± 4.3 mm) (all P ≤ 0.01). Subgroup analyses revealed accuracy gains were largest among target-proximity tasks performed by residents and for OOP approaches. Needle guidance technology improved first-pass completion from 214 (76.4%) per 280 to 249 (88.9%) per 280, a significant improvement of 16.4% (P = 0.001).
  
  
  CONCLUSIONS
  Passive magnetic NGT can improve accuracy of needle procedures, particularly among OOP procedures requiring close approach to sensitive targets, such as nerve blocks in anesthesiology practice.
authors.affiliation: From the *Department of Technical Communication, Science & Healthcare, Texas Tech University, Lubbock, TX; and †GE Healthcare, Technology and Medical Innovation Organization, Waukesha; ‡GE Healthcare, Ultrasound Business, Wauwatosa; and §GE Healthcare, Medical Affairs, Waukesha, WI.
authors.forename: Angela N
authors.initials: AN
authors.lastname: Johnson
authors.forename: Jeffery S
authors.initials: JS
authors.lastname: Peiffer
authors.forename: Nahi
authors.initials: N
authors.lastname: Halmann
authors.forename: Luke
authors.initials: L
authors.lastname: Delaney
authors.forename: Cindy A
authors.initials: CA
authors.lastname: Owen
authors.forename: Jeff
authors.initials: J
authors.lastname: Hersh
mesh_terms: D000072080:Anesthesiologists; D000818:Animals; D002983:Clinical Competence; D006801:Humans; D008280:Magnetics / Q000295:instrumentation / Q000379:methods*; D023421:Models, Animal; D009339:Needles; D009407:Nerve Block / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D011446:Prospective Studies; D034421:Sus scrofa; D013647:Task Performance and Analysis; D018084:Ultrasonography, Interventional / Q000295:instrumentation