Volumetric ultrasound imaging with a sparse matrix array and integrated fiber-optic sensing for robust needle tracking in interventional procedures

TL;DR

This work addresses the challenge of simultaneously visualizing anatomy and tracking interventional needles in three dimensions during ultrasound-guided procedures. It presents an integrated platform that couples a fiber-optic hydrophone embedded in the needle with a 2D sparse spiral ultrasound array to enable real-time volumetric imaging and 3D needle tip localization, using plane-wave imaging and a DAS-based reconstruction for tracking. The system achieves lateral and elevational resolutions on the order of 0.8–3.3 mm and axial resolution around 0.7 mm, with sub-millimeter tracking accuracy at the center that gradually degrades toward the edges and with depth. Validation in water, ex vivo tissue, and a femoral nerve block simulator demonstrates robust needle tracking, particularly when the needle tip visibility in US is limited, highlighting the potential to improve safety and efficacy in image-guided interventional procedures, albeit with current offline processing and limited real-time frame rates that can be mitigated with GPU acceleration and focused processing.

Abstract

Accurate visualization of interventional devices, such as medical needles, is essential for the safe and effective guidance of minimally invasive procedures. Ultrasound (US) imaging is widely used for needle guidance, but the two-dimensional nature of most clinical probes limits accurate three-dimensional (3D) localization, particularly of the needle tip. We present a novel system that integrates volumetric US imaging with 3D needle tracking by combining a fiber-optic hydrophone embedded in the needle and a sparse spiral US array. Real-time volumetric imaging was achieved using plane-wave techniques, while precise needle tip tracking was enabled through communication between the probe and hydrophone. The feasibility of the approach was demonstrated using a nerve block training phantom. This proof-of-concept system enables simultaneous volumetric anatomical imaging and 3D needle tip tracking, with strong potential to enhance the efficacy and safety of image-guided interventional procedures.

Figures (5)

• Figure 1: Schematic illustration of the 3D needle tracking and volumetric imaging system: (a) 2D matrix array probe with 256 active elements arranged in a spiral-pattern layout, with individual element positions indicated by dots. (b) conceptual diagram of the system in a clinical context (e.g., axillary nerve block procedures); (c) 20-gauge needle with an embedded fiber-optic hydrophone (FOH). ULA-OP 256: Ultrasound Advanced Open Platform with 256 channels; DAQ: Data Acquisition;
• Figure 2: Schematic illustration of the volumetric spatial resolution assessment setup and data processing pipeline. (a) Experimental setup; (b) Representative XZ plane slice of a volumetric ultrasound image acquired from a wire phantom; (c) Corresponding point spread function profiles in the lateral (X) and axial (Y) directions.
• Figure 3: Box-and-whisker plot of volumetric spatial resolution measured using a wire phantom. Measurements were acquired at depths ranging from 10 mm to 40 mm. Each box represents the interquartile range (IQR), with the top and bottom edges corresponding to the 75th and 25th percentiles, respectively; the black line within each box indicates the median. Whiskers extend to the most extreme data points within 1.5 times the IQR from the box edges.
• Figure 4: Measured tracking accuracy at varying spatial locations. The error bars indicate standard deviations from 3 repeated measurements.
• Figure 5: System validation using a femoral nerve block simulator. Representative results from a single needle insertion are shown in (a)-(d). (a) YZ-plane slices from a volumetric ultrasound image; (b) XZ-plane ultrasound image extracted from the volumetric ultrasound data, with its location indicated by the dashed box in (a). Tracked sampling positions (green crosses) are connected by a dashed line to illustrate the needle insertion path, with positions labeled P1, P2, and P3; (c) YZ-plane slices from a volumetric tracking image; (d) XZ-plane view of the volumetric tracking image, with its location indicated by the dashed box in (c), showing the tracked sampling positions; (e) Measured contrast-to-noise ratios (CNRs) for all three insertion attempts; Error bars represent standard deviations from 3 sampling locations. (f) Experimental setup. FOH: Fibre-Optic Hydrophone.