We aimed to demonstrate the feasibility of using contrast-enhanced ultrasound (CEUS)–guided high intensity focused ultrasound (HIFU) for the rapid identification and treatment of active bleeding from liver lacerations in a swine model. A two-element HIFU transducer was coupled to a probe and scanner for coregistered diagnostic imaging and ablation. Contrast imaging was performed for vessel targeting and bleeding identification. Eight swine received a 2 x 2 cm laceration across a superficial hepatic vein to induce active hemorrhage. Animals were then randomized to receive either CEUS imaging alone or CEUS-guided HIFU treatment. Subsequently, lacerations were created in an additional eight swine, treated with CEUS-guided HIFU, and followed for 24 hours.

Control animals did not achieve hemostasis, while all swine treated with CEUS-guided HIFU achieved hemostasis within 60 seconds of treatment and had less blood loss (60 mL; interquartile range [IQR], 40–125 mL vs. 725 mL; IQR, 410–925 mL; p = 0.016). For the survival studies, hemostasis was achieved after 2 to 6, 45-second treatment cycles (median, 2.5 treatments). The average total blood loss in the survival cohort was 105 mL (IQR, 41–325 mL). There were no changes in vital signs between the pre- and postlaceration control (p > 0.10). No changes were observed in blood cell counts prelaceration and 24 hours posthemostasis (p >> 0.25). Importantly, all animals survived for the full 24-hour monitoring period. On gross pathologic examination, no apparent damage was detected in the adjacent organs or liver ducts. This preclinical study suggests that CEUS-guided HIFU is a promising tool for the noninvasive rapid identification and subsequent treatment of active bleeding from liver lacerations.

Contrast-enhanced ultrasound (CEUS) shows promise in solid organ trauma by identifying areas of disrupted perfusion. In contrast, B-Flow ultrasound offers high fidelity imaging of larger vessels. We hypothesize that contrast-enhanced B-Flow (CEB-Flow) will improve accuracy of hepatic vessel injury delineation, as an adjunct tool to CEUS and future ultrasound-guided therapies. Imaging data was collected using our IACUC approved swine model for traumatic liver injury. All procedures were approved within this IACUC protocol. Sonography was performed using a Logiq E10 scanner with C1-6 probe (GE HealthCare). After ultrasound guided liver trauma, we performed open-abdomen B-Mode ultrasound, CEUS, and CEB-Flow of the injury during infusion of Definity (Lantheus Medical Imaging, N. Billerica, MA). CEUS was performed using coded harmonic imaging and CEB-Flow using a commercial package (GE Healthcare). Twelve swine were used for analysis. Three blinded interpreters were asked to identify injured liver parenchyma and lacerated vessels. Identification rates were compared using ultrasound-guided laceration images and pathology confirmation as a reference standard. Liver injury identification ranged from 88.3% to 100% on CEUS and 50% to 66.7% on CEB-Flow. Consensus identification rates in identifying parenchymal injury were not significantly different (91.7% CEUS vs. 66.7% CEB-Flow, p = .25). Lacerated vessel identification ranged from 41.7% to 58.3% for CEUS and 75.0% to 91.7% for CEB-Flow. Specifically, CEB-Flow demonstrated improved consensus in identifying lacerated vasculature (41.7% CEUS vs. 91.7% CEB-Flow, p = .041). In this swine model study, the combination of CEUS and CEB-Flow could accurately identify and localize traumatic hepatic injury. CEB-Flow may better characterize vessel injury, which in turn may direct and improve bedside management.

Transient acoustic holography is a useful technique for characterization of ultrasound transducers. It involves hydrophone measurements of the 2-D distribution of acoustic pressure waveforms in a transverse plane in front of the transducer—a hologram—and subsequent numerical forward projection (FP) or backward projection of the ultrasound field. This approach enables full spatiotemporal reconstruction of the acoustic field, including the vibrational velocity at the transducer surface. This allows identification of transducer defects as well as structural details of the radiated acoustic field such as sidelobes and hot spots. However, numerical projections may be time-consuming ( 10¹⁰ – 10¹¹ operations with complex exponents). Moreover, backprojection from the measurement plane to the transducer surface is sensitive to misalignment between the axes of the positioning system and the axes associated with the transducer. This article presents an open-access transducer characterization toolbox for use in MATLAB or Octave on Windows computers (https://github.com/pavrosni/xDDx/releases). The core algorithm is based on the Rayleigh integral implemented in C++ executables for graphics and central processing units (GPUs and CPUs). The toolbox includes an automated procedure for correcting axes misalignments to optimize the visualization of transducer surface vibrations. Beyond using measured holograms, the toolbox can also simulate the fields radiated by user-defined transducers. Measurements from two focused 1.25-MHz 12-element sector transducers (apertures of 87 mm and focal distances of 65 and 87 mm) were used with the toolbox for demonstration purposes. Simulation speed tests for different computational devices showed a range of 0.2 s – 3 min for GPUs and 1.6 s – 57 min for CPUs.