EpiGuide 2D: Visibility Assessment of a Novel Multi-Channel Out-of-Plane Needle Guide for 2D Point of Care Ultrasound

The desire to improve patient safety and clinical precision has prompted research in the development of a real-time, single operator, image-guided solution for neuraxial anesthesia. Ultrasound is ideal for this application given that it is real-time, non-ionizing, and with recent advances, ultra-portable. Previous work has investigated the use of 3D ultrasound and 2D in-plane imaging to track needle insertions but faced barriers to successful clinical translation. The EpiGuide 2D is a novel multi-channel out-of-plane needle guide that addresses deficiencies observed in prior designs. Specifically, it leverages beam thickness, an inherent imaging artefact, to provide needle visibility over a range of depths. The current work investigates the ability of the EpiGuide 2D to visualize out-of-plane needle insertions. Two different needle types are explored with 9 needle angles over 5 distinct imaging depths. Benchtop testing is performed to assess stability of the guide's open channels. Subsequent water bath testing is used to establish baseline visibility metrics across all angles. Finally, testing on an ex vivo porcine model is performed. A total of n=424 needle insertions are performed. Visible range and contrast-to-noise ratios are measured for each insertion. As needle angle approached parallel to the imaging plane, visible range increased. Needle echogenicity also increased the visible range of the needle in the water bath setting but was not found to have a statistically significant effect on visible range in the porcine model. The EpiGuide 2D accommodates needle visualization in tissue for depths of 21 mm to 53 mm. Further in vivo studies are warranted.