Gel Phantom Models Research Articles

Simulation-based ultrasound-guided regional anesthesia education: a national survey of Canadian anesthesiology residency training programs.

Simulation-based education in ultrasound-guided regional anesthesia (UGRA) improves knowledge, skills, and patient outcomes. Nevertheless, it is not known how simulation-based UGRA education is used across Canada. We aimed to characterize the current use of simulation-based UGRA education in Canadian anesthesiology residency training programs. We developed and distributed a structured national survey to simulation leads of all 17 Canadian anesthesiology residency training programs. The survey inquired about program demographics, simulation modalities, facilitators and barriers to simulation use, use for assessment, and beliefs around simulation-based UGRA education. We gathered data from August to November 2023 and summarized our findings descriptively. Fifteen programs (88%) responded to our survey. Eight programs (53%) used UGRA simulation for technical training and nine programs (60%) for nontechnical training. The most common simulators used were live model scanning (13 programs, 87%) and gel phantom models (7 programs, 47%). Five programs (33%) mandated simulation-based UGRA in their curriculum. We found that deliberate practice and improved patient safety were most valued in simulation training while lack of funding and faculty availability were the most common barriers to implementation. Most respondents agreed that formative simulation-based education would improve trainee skills and called for greater standardization. Nevertheless, there were mixed responses regarding summative UGRA simulation and the need for simulation proficiency before clinical practice. Our findings show significant variations in simulation implementation and views on UGRA simulation-based education among Canadian anesthesiology residency training programs. Future studies should explore avenues to overcome barriers and improve knowledge translation in UGRA.

Microbubble-Facilitated Ultrasound Catheter Ablation Causes Microvascular Damage and Fibrosis

High-intensity ultrasound (US) ablation produces deeper myocardial lesions than radiofrequency ablation. The presence of intravascular microbubble (MB) contrast agents enhances pulsed-wave US ablation via cavitation-related histotripsy, potentially facilitating ablation in persistently perfused/conducting myocardium. US ablation catheters were developed and tested in the presence of MBs using ex vivo and in vivo models. High-frame-rate videomicroscopy and US imaging of gel phantom models confirmed MB destruction by inertial cavitation. MB-facilitated US ablation in an ex vivo perfused myocardium model generated shallow (2 mm) lesions and, in an in vivo murine hindlimb model, reduced perfusion by 42% with perivascular hemorrhage and inflammation, but no myonecrosis.

Gel Phantom Models for Radiofrequency and Microwave Ablation of the Liver.

Heat-based percutaneous thermal ablation techniques have emerged as popular and effective treatments for liver cancer. As the technology continues to evolve, there is a need for optimized methods for experimentation to identify advantageous modifications and developments. Given that assessing and comparing resulting ablation zones in animal models are costly and resource-intensive, in vitro gel phantom models can serve an important role for early-stage experimentation. There exist several gel phantom recipes that have been reported in the literature. In this review, we will review the various recipes, the pros and cons to the existing models, and future potential directions.

Survey of regional anesthesiology fellowship directors in the USA on the use of simulation in regional anesthesiology training

BackgroundDespite a growing interest in simulated learning, little is known about its use within regional anesthesia training programs. In this study, we aimed to characterise the simulation modalities and limitations...

Injectable Biodegradable Multimodal Mammography Marker.

Introducing temporary markers for imaging studies is an idea, which in the proper clinical settings can be advantageous for patient compliance and in selected cases where a permanent marker is nondesirable. Hence, we developed injectable marker formulation using a biodegradable "pasty polymer" of poly(ricinoleic acid-co-sebacic acid) (PSA:RA) containing iodixanol and iron oxide as contrast agents that can serve as a visual marker for the region suspected to have tumor growth. The goal of this work is to noninvasively evaluate the visibility, shape, and degradation of the injectable PSA:RA formulation using magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound (US). Prescreening of the marker formulation was performed under MRI and CT scanning using agar gel phantom models with poly(l-lactide-co-ε-caprolactone) (PCL:LA) solid inserts (clips) that contained varying combinations of the contrast agents. The contrast agent combination with the PCL:LA clip that had the best visibility in both MRI and CT was selected and additionally tested as in PSA:RA formulation. Further, we evaluated the PSA:RA marker placement in bovine liver and poultry muscles. The PSA:RA formulation is predictable with good MRI, CT, and US visibility and shows no in vivo systemic toxicity symptoms when implanted subcutaneously in mice. Further, the advantage of PSA:RA formulation is its undefined shape and ease of injecting through a small gauge needle, making it possible to reach into the regions of the body.

Teaching sonoanatomy to anesthesia faculty and residents: utility of hands-on gel phantom and instructional video training models

Study objectiveThousands of patients worldwide annually receive neuraxial anesthesia and analgesia. Obesity, pregnancy, and abnormal spinal anatomy pose challenges for accurate landmark palpation. Further, spinal sonoanatomy is not uniformly taught in residency education, even though its use has previously been shown to improve identification of relevant structures and decrease procedural complications and failure rates. The aim of this study was to evaluate the use of hands-on gel phantom and instructional video training for teaching spinal sonoanatomy among anesthesiology faculty and residents. DesignTwenty-three residents and 27 anesthesiologists were randomized to gel phantom, video teaching, and control groups. SettingAcademic Hospital. MeasurementsSuccessful identification of spinal sonoanatomy was attempted on a human volunteer before and immediately after the respective intervention and 3 weeks later. Perceived knowledge and training modality satisfaction were assessed using modified Likert scales. InterventionsGel phantom and video teaching groups compared with control (no intervention). Main resultsBoth interventions significantly improved spine sonoanatomy identification accuracy. Logistic regression analysis demonstrated both interventions improved the odds of transverse process (gel 12.61, P = .013; video 7.93, P = .030) and lamina (gel 65.12, P = .003; video 8.97, P = .031) identification. Perceived knowledge of basic spinal anatomy and spinal sonoanatomy improved in the intervention versus control groups. Mean (SD) modified Likert scale scores for learning satisfaction (1 = unsatisfied, 10= very satisfied) were 8.1 (1.5) and 8.0 (1.7) for hands-on gel phantom and instructional video training participants, respectively. ConclusionUse of hands-on gel phantom or instructional video training can improve anesthesia staff and resident knowledge of lumbar spine sonoanatomy.

Method to reduce non-specific tissue heating of small animals in solenoid coils

Purpose: Solenoid coils that generate time-varying or alternating magnetic fields (AMFs) are used in biomedical devices for research, imaging and therapy. Interactions of AMF and tissue produce eddy currents that deposit power within tissue, thus limiting effectiveness and safety. We aim to develop methods that minimise excess heating of mice exposed to AMFs for cancer therapy experiments.Materials and methods: Numerical and experimental data were obtained to characterise thermal management properties of water using a continuous, custom water jacket in a four-turn simple solenoid. Theoretical data were obtained with method-of-moments (MoM) numerical field calculations and finite element method (FEM) thermal simulations. Experimental data were obtained from gel phantoms and mice exposed to AMFs having amplitude >50 kA/m and frequency of 160 kHz.Results: Water has a high specific heat and thermal conductivity, is diamagnetic, polar, and nearly transparent to magnetic fields. We report at least a two-fold reduction of temperature increase from gel phantom and animal models when a continuous layer of circulating water was placed between the sample and solenoid, compared with no water. Thermal simulations indicate the superior efficiency in thermal management by the developed continuous single chamber cooling system over a double chamber non-continuous system. Further reductions of heating were obtained by regulating water temperature and flow for active cooling.Conclusions: These results demonstrate the potential value of a contiguous layer of circulating water to permit sustained exposure to high intensity alternating magnetic fields at this frequency for research using small animal models exposed to AMFs.

Benchmarking the ERG valve tip and MRI Interventions Smart Flow neurocatheter convection-enhanced delivery system's performance in a gel model of the brain: employing infusion protocols proposed for gene therapy for Parkinson's disease

Convection-enhanced delivery (CED) is an advanced infusion technique used to deliver therapeutic agents into the brain. CED has shown promise in recent clinical trials. Independent verification of published parameters is warranted with benchmark testing of published parameters in applicable models such as gel phantoms, ex vivo tissue and in vivo non-human animal models to effectively inform planned and future clinical therapies. In the current study, specific performance characteristics of two CED infusion catheter systems, such as backflow, infusion cloud morphology, volume of distribution (mm3) versus the infused volume (mm3) (Vd/Vi) ratios, rate of infusion (µl min−1) and pressure (mmHg), were examined to ensure published performance standards for the ERG valve-tip (VT) catheter. We tested the hypothesis that the ERG VT catheter with an infusion protocol of a steady 1 µl min−1 functionality is comparable to the newly FDA approved MRI Interventions Smart Flow (SF) catheter with the UCSF infusion protocol in an agarose gel model. In the gel phantom models, no significant difference was found in performance parameters between the VT and SF catheter. We report, for the first time, such benchmark characteristics in CED between these two otherwise similar single-end port VT with stylet and end-port non-stylet infusion systems. Results of the current study in agarose gel models suggest that the performance of the VT catheter is comparable to the SF catheter and warrants further investigation as a tool in the armamentarium of CED techniques for eventual clinical use and application.