Development and Assessment of Two Novel Pitting Designs for Increased Needle Visibility under Ultrasound

Nerve endings are particularly difficult to target during peripheral nerve block (PNB) procedures, so ultrasound-guided needles are of immense importance to guarantee safe and efficient delivery of the anesthetic to the target nerve. Despite significant progress in needle visualization with ultrasound imaging, there are still several factors that lead to poor needle visibility, the main factor being insertion angle. Introducing cavities and holes in the needle at specific intervals through pitting corrosion may alter the ultrasonic feedback from the sensor, thereby resulting in improved clarity of the reconstructed image. The purpose of this experiment is to investigate the effectiveness of two novel pitting designs on the needle’s visibility under ultrasound. Two different designs and two depths of cut are tested in a 22 factorial that is blocked by insertion angle: a uniform and a non-uniform design. Needles were cut using a Plain Jane and Igor laser cutter and imaged using a GE Logig e BT12 ultrasound imaging machine. Images were compared visually and objectively by using a tool in Photoshop to calculate the luminosity of the needle. Two videos were also taken capturing the difficulty of imaging surgical needles. Results showed that pitting had a major impact on needle visibility at 30° and a marginal impact at 0°. The videos supported these results as it was considerably more difficult to locate the control needle than the experimental needle. This suggests the probe must be in a specific plane with the control needle for it to be visible while the experimental needle is much more lenient. Results from the two depths of cuts showed similar results in that the designs which were cut twice were more visible than their counterparts at 30°. The study showed that pitting has positive effects on needle visibility; it improves visibility by increasing the luminescence of the needle and by decreasing its sensitivity to probe position.