SonoGuar: A Self-healing Hydrogel for Higher Fidelity Ultrasound-guided Procedure Training.

introductionUltrasound-compatible procedural phantoms are critical for vascular access training, but commercial models are expensive, degrade with use, and provide limited simulation of key procedural steps. Existing low-cost alternatives often lack durability and fidelity.

methodsWe synthesized a novel, self-healing, ultrasound-compatible hydrogel (SonoGuar) using guar gum, borax, glycerol, oil, and water. We constructed vascular-access task trainers and evaluated SonoGuar across three domains: 1) rheological analysis of viscoelastic recovery after injury; 2) a blinded ultrasound image comparison study comparing SonoGuar against a commercial model; and 3) a prospective, randomized, single-blind crossover simulation study comparing SonoGuar to a commercial model with 41 participants (medical students, residents, and attendings).

resultsAt grocery store material prices, one kilogram of SonoGuar took 10 minutes of active time and about $3 to fabricate, including vessel-mimic balloons. The commercial comparison model was quoted at $350 for a single replacement insert. SonoGuar recovered its viscoelastic profile within 30 minutes of injury and demonstrated visible healing of needle tracts by five hours. In the image comparison, SonoGuar was 1.8 times more likely than the commercial model to be selected as resembling human tissue in a head-to-head comparison (64.5% SonoGuar vs 35.5% commercial model, P < .001). In simulation, 41-residents and attendings rated SonoGuar higher than the commercial phantom across all model aspects, including anatomy identification, appearance, tactile feedback, and needle visualization (average of 4.47 vs 3.77 on a 5-point Likert scale, P < .01). After cost was disclosed, all preferred SonoGuar. Medical students rated both models similarly across all model aspects and demonstrated increased levels of confidence after training with SonoGuar or commercial phantom (pre-simulation average confidence on a 5-point Likert scale of 1.46 and post-simulation average of 3.54 and 3.37, respectively, both comparisons P < .05).

conclusionA do-it-yourself, high-fidelity hydrogel with self-healing properties, SonoGuar can be rapidly fabricated and is suitable for realistic, durable, and scalable ultrasound-guided procedure training. The low-cost hydrogel outperformed a leading commercial model in imaging realism, user confidence, and overall preference among experienced clinicians.