Smart Photoacoustic Beacon for Accurate Vascular Access in Prolonged Field Care- MHSRS 2024

zhang h, schulz-hildebrandt h, domingue carrerra u, panikkar a, tearney g

Abstract accepted for poster presentation at the 2024 Military Health System Research Symposium

Ultrasound guidance is essential for vascular access. However, ultrasound is limited by the unreliable visibility of the needle tip. To address this issue, our team developed a photoacoustic imaging device that differentiates between arteries and veins by inserting a fiber into the cannula for visualization. However, this technology required an external ultrasound system, which was not compatible for battlefield application. In this abstract, we report on our next generation needle tracking system that utilizes portable ultrasound to achieve robust needle tip tracking. These advances can potentially make accurate needle tip tracking practical on the battlefield. This needle tip tracking technology is based on Light- enhanced Ultrasound (LEUS) that integrates near-infrared light with ultrasound detection to enhance the capabilities of ultrasound in trauma care. LEUS features a novel photoacoustic mode that enables visualization of light-absorbing structures by detecting light-induced sound waves. Here, we utilize this effect to generate a photoacoustic beacon via fiber delivery. Specifically, we have designed a 130-um trench on the outer wall of a needle (800-um inside diameter) to contain the fiber, and we coated a 140- um photoacoustic beacon with a mixture of graphite and biocompatible epoxy at the tip of the fiber. Our coated beacon source emits the light-induced ultrasound signal with 5-mJ illumination. Additionally, we developed software to acquire ultrasound and photoacoustic signals simultaneously, enabling the real- time display of overlaid duplex images. We conducted testing by puncturing the smart beacon needle in a vascular access ultrasound phantom (VATA Inc.). In the pure Ultrasound B mode, the structure of the needle tip was challenging to discern. However, when switching to the LEUS system, the beacon signal consistently appeared as a red spot, clearly representing of the needle tip. Remarkably, the red spot remained visible at the maximum depth of 30 ± 0.23 mm. Throughout this depth range, the signal-to- noise ratio of the beacon signal remained constant at 15dB, demonstrating a stable signal suitable for vascular guidance. Here we show a portable LEUS-driven vascular access guidance system with greatly enhanced needle tip visualization. This technology has great potential for improving the accuracy of vascular access by emergency medical providers without extensive vascular training.