Polyvinyl Alcohol Cryogel Research Articles

Physically Cross-Linked PVA Hydrogels as Potential Wound Dressings: How Freezing Conditions and Formulation Composition Define Cryogel Structure and Performance

Objectives: Hydrogels produced using the freeze–thaw method have demonstrated significant potential for wound management applications. However, their production requires precise control over critical factors including freezing temperature and the choice of matrix-forming excipients, for which no consensus on the optimal conditions currently exists. This study aimed to address this gap by evaluating the effects of the above-mentioned variables on cryogel performance. Methods: Mechanical properties, absorption capacity, and microstructure were assessed alongside advanced analyses using differential scanning calorimetry (DSC) and low-field nuclear magnetic resonance relaxometry (LF TD NMR). Results: The results demonstrated that fully hydrolyzed polyvinyl alcohol (PVA) with a molecular weight above 61,000 g/mol is essential for producing high-performance cryogels. Among the tested formulations, an 8% (w/w) PVA56–98 solution (Mw~195,000; DH = 98.0–98.8%) with 10% (w/w) propylene glycol (PG) provided the best balance of stretchability, durability, and low adhesion. Notably, while −25 °C is often used for cryogel preparation, freezing the gel precursor at −80 °C yielded superior results, producing materials with more open, interconnected structures and enhanced mechanical strength and elasticity—deviating from conventional practices. Conclusions: The designed cryogel prototypes exhibited functional properties comparable to or even surpassing commercial wound dressings, except for absorption capacity, which remained lower. Despite this, the cryogel prototypes demonstrated potential as wound dressings, particularly for use in dry or minimally exuding wounds. All in all, this study provides a comprehensive analysis of the physicochemical and functional properties of PVA cryogels, establishing a strong foundation for the development of advanced wound dressing systems.

Assessing suitability and stability of materials for a head and neck anthropomorphic multimodality (MRI/CT) phantoms for radiotherapy.


This study aims to identify and evaluate suitable and stable materials for developing a head and neck anthropomorphic multimodality phantom for radiotherapy purposes. These materials must mimic human head and neck tissues in both computed tomography (CT) and magnetic resonance imaging (MRI) and maintain stable imaging properties over time and after radiation exposure, including the high levels associated with linear accelerator (linac) use.
Approach:
Various materials were assessed by measuring their CT numbers and T1 and T2 relaxation times. These measurements were compared to literature values to determine how closely the properties of the candidate materials resemble those of human tissues in the head and neck region. The stability of these properties was evaluated monthly over a year and after radiation exposure to doses up to 1000 Gy. Statistical analyses were conducted to identify any significant changes over time and after radiation exposure.
Main Results:
10% and 12.6% Polyvinyl alcohol cryogel (PVA-c) both exhibited T1 and T2 relaxation times and CT numbers within the range appropriate for brain grey matter. 14.3% PVA-c and some plastic-based materials matched the MRI properties of brain white matter, with CT numbers close to the clinical range. Additionally, some plastic-based materials showed T1 and T2 relaxation times consistent with MRI properties of fat, although their CT numbers were not suitable. Over time and after irradiation, 10% PVA-c maintained consistent properties for brain grey matter. 12.6% PVA-c's T1 relaxation time decreased beyond the range after the first month.
Significance:
This study identified 10% PVA-c as a substitute for brain grey matter, demonstrating stable imaging properties over a year and after radiation exposure up to 1000 Gy. However, the results highlight a need for further research to find additional materials to accurately simulate a wider range of human tissues.&#xD.

Wastewater treatment optimization utilizing polyvinyl alcohol cryogel immobilized microalgae for nutrient removal

This study investigated the use of polyvinyl alcohol (PVA) cryogels to immobilize microalgae for wastewater treatment. Chlorella sorokiniana was successfully entrapped in PVA cryogels via repeated freeze/thaw cycles. The nutrient removal efficiency of these cryogels was tested in a continuously stirred photobioreactor under varying conditions, both with and without the addition of an organic carbon source (sodium acetate). The presence of organic carbon significantly enhanced nutrient removal. Specifically, PVA cryogels with immobilized C. sorokiniana achieved 100% nitrogen removal and 97.2% phosphorus removal under mixotrophic conditions. Furthermore, the maximum nutrient removal capacities of the PVA cryogels were found to be 0.033 mg-N/cube·day for nitrogen and 0.0047 mg-P/cube·day for phosphorus. As the inorganic carbon (bicarbonate) concentration increased from 5 to 100 mg/L, the N/P ratio rose from 6 to 8, with a higher N/P ratio of 10 observed when nitrate nitrogen was used as the nitrogen source, compared to ammonia nitrogen, at 100 mg/L bicarbonate. This study offers an effective method for using microalgae immobilized in PVA cryogels for wastewater treatment. The findings highlight the potential for PVA cryogels to significantly improve nutrient removal efficiency, particularly in the presence of organic carbon sources, thereby enhancing bioreactor performance. High nitrogen and phosphorus removal efficiencies can help reduce eutrophication in water bodies, protect aquatic ecosystems, and enable nutrient recovery and reuse, supporting a circular economy in wastewater treatment practices.

Efficient removal of polycyclic aromatic hydrocarbons from aqueous solutions using green cyclodextrin-maltodextrin nanosponge incorporated polyvinyl alcohol cryogel

Developing efficient adsorbents for removing polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions is a significant and worthwhile approach. In this study, we showcase a method for fabricating β-cyclodextrin-maltodextrin nanosponges (βCD-MD) incorporated polyvinyl alcohol (PVA) cryogel for removing PAHs from aqueous solutions. The composite nanosponges enhanced the adsorption efficiency of PAHs such as Naphthalene, Acenaphthene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, and Benzo[a]pyrene from water samples and the porous PVA cryogel helped to entrap and prevent the loss of the adsorbent. This efficacy was attributed to the strong affinities of PAHs toward βCD-MD nanosponges, facilitated by hydrophobic interactions between the analytes and the hydrophobic inner region present in both dextrins. The removal efficiency of the prepared βCD-MD/PVA composite cryogel was more than 95 % for all 8 PAHs (C0 = 5.0 mg/L) in less than 30 min, and the experimental data were well described by the Freundlich isotherm and the pseudo-second-order kinetic model. Additionally, the βCD-MD/PVA composite cryogel exhibited a maximum adsorption capacity ranging from 16.34 to 18.49 mg/g for eight PAHs. Moreover, the thermodynamic study revealed that the adsorption of PAHs was an endothermic and spontaneous process. The βCD-MD/PVA composite cryogel exhibited an abundance of polar functional groups along with numerous hydrophobic cavities and regions. It demonstrated high mechanical and thermal stability and maintained high removal efficiency even after seven adsorption–desorption cycles. Overall, it was concluded that βCD-MD/PVA composite cryogel can be utilized as a high-performance, eco-friendly, and sustainable alternative for PAH removal.

A porous composite sorbent incorporating a metal organic framework and zinc oxide in cryogel to extract carbamate pesticides

A composite sorbent was designed and fabricated by incorporating the Materials of Institute Lavoisier (MIL-101) and zinc oxide (ZnO) into polyvinyl alcohol (PVA) cryogel. The composite sorbent was produced to extract carbamates (carbofuran, carbaryl, isoprocarb and diethofencarb) by in-syringe solid phase extraction (SPE). MIL-101 and ZnO enhanced the adsorption of the carbamates by creating π-π stacking and hydrogen bonding, while porous PVA cryogel acted as a solid support which helped to reduce backpressure in the system. The extraction of the target carbamates was optimized by varying the amount of MIL-101 and ZnO used in the sorbent fabrication, desorption conditions, sample pH, ionic strength, sample flow rate and sample volume. The extracted target carbamates were quantitatively determined using high performance liquid chromatography technique. The developed method exhibited linearity from 1.0 to 150.0 μgL−1 for all four target carbamate pesticides with a limit of detection 0.3 µg/L. The method identified carbamates in fruit juice and white wine, obtaining recoveries from 78.1 to 108.2 % and the relative standard deviation (RSD) lower than 6.3 %. The developed composite sorbent showed good accuracy, is simple to fabricate, works rapidly and can be used for 17 extraction-regeneration cycles.

MRI-compatible abdomen phantom to mimic respiratory-triggered organ movement while performing needle-based interventions.

In vivo studies are often required to prove the functionality and safety of medical devices. Clinical trials are costly and complex, adding to ethical scrutiny of animal testing. Anthropomorphic phantoms with versatile functionalities can overcome these issues with regard to medical education or an effective development of assistance systems during image-guided interventions (e.g., robotics, navigation/registration algorithms). In this work, an MRI-compatible and customizable motion phantom is presented to mimic respiratory-triggered organ movement as well as human anatomy. For this purpose, polyvinyl alcohol cryogel (PVA-C) was the foundation for muscles, liver, kidneys, tumors, and remaining abdominal tissue in different sizes of the abdominal phantom body (APB) with the ability to mimic human tissue in various properties. In addition, a semi-flexible rib cage was 3D-printed. The motion unit (MU) with an electromagnetically shielded stepper motor and mechanical extensions simulated a respiration pattern to move the APB. Each compartment of the APB complied the relaxation times, dielectricity, and elasticity of human tissue. It showed resistance against mold and provided a resealable behavior after needle punctures. During long-term storage, the APB had a weight loss of 2.3%, followed by changes to relaxation times of 9.3% and elasticity up to 79%. The MU was able to physiologically appropriately mimic the organ displacement without reducing the MRI quality. This work presents a novel modularizable and low-cost PVA-C based APB to mimic fundamental organ motion. Beside a further organ motion analysis, an optimization of APB's chemical composition is needed to ensure a realistic motion simulation and reproducible long-term use. This phantom enhances diverse and varied training environments for prospective physicians as well as effective R&D of medical devices with the possibility to reduce in vivo experiments.

A magnetic stir bar sorbent of metal organic frameworks, carbon foam decorated zinc oxide and cryogel to enrich and extract parabens and bisphenols from food samples

A porous composite magnetic stir bar adsorbent was fabricated for the extraction and enrichment of parabens and bisphenols from selected beverage samples. The adsorbent comprised a metal organic framework, carbon foam decorated zinc oxide and magnetic nanoparticles embedded in polyvinyl alcohol cryogel. The porous composite stir bar adsorbent could adsorb parabens and bisphenols via hydrogen bonding, π-π and hydrophobic interactions. In the best conditions, linearity was good from 5.0 to 200.0 µg/L for methyl paraben, ethyl paraben and bisphenol A and from 10.0 to 200.0 µg/L for bisphenol B and butyl paraben. Limits of detection ranged from 1.5 to 3.0 µg/L. The developed composite stir bar was successfully applied to extract and determine parabens and bisphenols in fruit juice, beer and milk. Recoveries ranged from 89.5 to 99.5 % with RSDs lower than 6 %. The developed sorbent and new methodology were evaluated in terms of its green character with satisfactory results.

A hierarchically porous PEDOT embedded cryogel for in-syringe solid phase extraction of parabens in beverages

A hierarchically porous adsorbent was fabricated using polyethylene dioxythiophene (PEDOT) embedded in a polyvinyl alcohol cryogel. This adsorbent was designed for use in the in-syringe solid-phase extraction (IS-SPE) of parabens present in beverage samples. The creation of a hierarchical pore system was achieved through a reaction between a hydrochloric acid solution and calcium carbonate, strategically introduced during the cryogel synthesis within a needle hub. The porous structure of the cryogel allowed for efficient entrapment of adsorption materials, significantly increasing the number of available adsorption sites. Additionally, PEDOT was incorporated to enhance paraben adsorption through hydrophobic and π-π interactions. High-performance liquid chromatography was employed to quantify the extracted parabens. Under optimized conditions, the developed method exhibited detection limits ranging from 0.15 to 0.25 µg L–1 and quantification limits ranging from 0.50 to 1.0 µg L–1. The technique was successfully applied to assess parabens in various beverage samples, consistently obtaining extraction recoveries between 88.4% and 98.4%, and relative standard deviations (RSDs) below 6%. We conclude that the in-syringe extraction approach offers a straightforward and efficient method, while the composite adsorbent demonstrates ease of preparation and robust reproducibility, allowing for twelve extraction–desorption cycles.

PREPARATION AND PROPERTIES OF BIODEGRADABLE CRYOGELS BASED ON POLYVINYL ALCOHOL AND POTATO STARCH FOR USE IN SOIL EROSION CONTROL

Compositions for the formation of three-component elastic cryogels based on the aqueous solutions of polyvinyl alcohol (PVA) and potato starch are proposed. It is shown that the viscosity of aqueous solutions depends both on the kind of polymer and on the total content of polymers in the system. The elasticity modulus of three-component cryogels depends on the concentration of starch in them and increases from 5 to 15 kPa with the addition of starch in the amount of 1-5 wt. %. By introducing a dispersed material (soil) into the matrix of two-and three-component cryogels, due to the high adhesion of the polymer to the filler, the filled cryogels were obtained, with the elasticity modulus 16 times higher than that of cryogels without the filler. The introduction of potato starch in the amount of 5 wt. % into PVA cryogel caused an increase in the time of its complete drying by 24 h, and an increase in its destruction during exposure in water by 5% within a week. Two-component cryogels exhibited sharply different types of behaviour during storage in water: PVA cryogel did not lose its mass, while mass loss by the cryogel of potato starch was 11% within a week. A decrease in the mass of three-component cryogels by 75-89% due to the loss of moisture and destruction was demonstrated in the soil test under the action of aboriginal soil microflora. The mass loss by the two-component cryogel based on PVA was 60%. Soil testing for phytotoxicity after the destruction of three-component cryogels revealed a decrease in the germination capacity of white mustard (Sinapis alba L.) by 2-10% with respect to the reference experiment, depending on starch content, while for the reference two-component PVA cryogel the corresponding decrease was by 18%. Cryostructuring of the upper soil layer by PVA cryogel caused an increase in the dry above-ground mass of plants by 3.2% in comparison with the reference, while the cryogel with potato starch caused an increase by 7.1%, and cryogel based on PVA and potato starch gave 9.4%.

Superficial Bifurcated Microflow Phantom for High-Frequency Ultrasound Applications

To evaluate and optimize high-frequency ultrasound (HFUS) imaging techniques that visualize the morphology of microscale vasculatures, many studies have used flow phantoms with straight channels. However, the previous phantoms lack the complexity of microvessels to simulate a realistic vascular environment in a shallow depth. This study was aimed at devising a new protocol for fabrication of a microflow phantom with bifurcated geometry at a superficial region. The proposed protocol involved the following features: (i) a bifurcated flow tract model 300 µm in diameter was debossed on the surface of a tissue slab made of polyvinyl alcohol cryogel, and (ii) a wall-less lumen was created via bonding tissue slabs to put a lid on the debossed flow tract. The structure of the created microflow phantom was evaluated using 2-D and 3-D power Doppler imaging with a 30 MHz HFUS modality. Ultrasound imaging revealed that the desired flow tract with bifurcation was successfully created in the phantom at a depth of 2-5 mm from the ultrasound probe. The diameters of the flow tract measured in the axial direction were 307 ± 3.7 µm in the parent branch and 232 ± 18.2 and 256 ± 23.3 µm in the two daughter branches, respectively. The experiments revealed that the proposed protocol for creating a microscale intricate flow tract with desired dimensions and depth is valid. This new phantom will facilitate further improvement in the ultrasound technologies for the precise visualization of superficial complex vasculatures such as those in skin layers.

Anthropomorphic Carotid Artery Phantom for Ultrasound Flow and Vessel Wall Elastography Imaging.

Shear wave elastography imaging (SWE) is a non-invasive US technique that has been developed to provide quantitative information about tissue elasticity. This technique might be useful in the identification of vascular risk factors. Arterial wall thickness and inner diameter vary with age and disease, which may impact shear wave propagation. The effect of arterial geometry on SWE has not yet been thoroughly investigated. Therefore, this study aimed to investigate the impact of different wall thickness, pulsation and imaging planes on YM estimates, to gain more information about the source of variability associated with SWE. Poly(vinyl alcohol) cryogel (PVA-c) fabrication has been used for phantom design and construction. The agar-based TMM was used to surround the tubes. The inlet and outlet of the phantom were connected to a programmable gear pump using c-flex tubing to form a closed loop. Image J profiling was used to clarify the anomalies further detected using SWE. The 4 F/T cycle vessel phantom has shown less YM variability than in the 6 F/T cycle. YM ranged from 8 kPa for a 1 mm thickness tube to 53 kPa for the thickest 6 mm wall thickness for the softer 4 F/T cycle tube. Vessel phantoms embedded in TMM show higher variability than vessel phantoms submerged in water. YM ranged from 32 kPa for a 1 mm thickness tube to 117 kPa for the thickest 6 mm wall thickness for the softer 4 F/T cycle tube. SWE variability in measurements was higher in phantoms embedded in TMM compared to those submerged in water. It is recommended that combine the transverse and longitudinal imaging planes to provide a better understanding of disease over the full vessel circumference.

A monolith graphene oxide and mesoporous carbon composite sorbent in polyvinyl alcohol cryogel to extract and enrich fluoroquinolones in honey

A monolith graphene oxide and mesoporous carbon composite sorbent in polyvinyl alcohol cryogel to extract and enrich fluoroquinolones in honey

Modeling and numerical analysis for mechanical characterization of soft tissue mechanism applying inverse finite element technique

Tissue-mimicking materials [e.g., polyvinyl alcohol cryogel (PVA-C)] are extensively used in clinical applications such as tissue repair and tissue engineering. Various mechanical testing techniques have been used to assess the biomechanical compatibility of tissue-mimicking materials. This article presents the development of inverse finite element (FE) techniques that are solved using numerical optimization to characterize the mechanical properties of PVA-C specimens. In this study, a numerical analysis where the displacement influence factor was employed in conjunction with a linear elastic model of finite thickness was performed. In the analysis, the effects of Poisson's ratio, specimen aspect ratio, and relative indentation depth were investigated, and a novel mathematical term was introduced to Sneddon's equation. In addition, a robust optimization algorithm was developed in MATLAB that utilized FE modeling for parameter estimation before it was rigorously validated.

Low-Cost Pseudo-Anthropomorphic PVA-C and Cellulose Lung Phantom for Ultrasound-Guided Interventions.

A low-cost custom-made pseudo-anthropomorphic lung phantom, offering a model for ultrasound-guided interventions, is presented. The phantom is a rectangular solidstructure fabricated with polyvinyl alcohol cryogel (PVA-C) and cellulose to mimic the healthy parenchyma. The pathologies of interest were embedded as inclusions containing gaseous, liquid, or solid materials. The ribs were 3D-printed using polyethylene terephthalate, and the pleura was made of a bidimensional reticle based on PVA-C. The healthy and pathological tissues were mimicked to display acoustic and echoic properties similar to that of soft tissues. Theflexible fabrication process facilitated the modification of the physical and acoustic properties of the phantom. The phantom's manufacture offers flexibility regarding the number, shape, location, and composition of the inclusions and the insertion of ribs and pleura. In-plane and out-of-plane needle insertions, fine needle aspiration, and core needle biopsy were performed under ultrasound image guidance. The mimicked tissues displayed a resistance and recoil effect typically encountered in a real scenario for a pneumothorax, abscesses, and neoplasms. The presented phantom accurately replicated thoracic tissues (lung, ribs, and pleura) and associated pathologies providing a useful tool for training ultrasound-guided procedures.

Bionic artificial penile Tunica albuginea

Bionic artificial penile Tunica albuginea

Extending arterial stiffness assessment along the circumference using beam-steered ARFI and wave-tracking: A proof-of-principle study in phantoms and ex vivo

BackgroundTo fully quantify arterial wall and plaque stiffness, acoustic radiation force impulse (ARFI)-induced wave-tracking along the entire vessel circumference is desired. However, attenuation and guided wave behavior in thin vessel walls limits wave-tracking to short trajectories. This study investigated the potential of beam-steered ARFI and wave-tracking to extend group velocity estimation over a larger proportion of the circumference compared to conventional 0° ARFI-induced wave-tracking. MethodsSeven vessel-mimicking polyvinyl alcohol cryogel phantoms with various dimensions and compositions and an ex vivo human carotid artery were imaged in a dedicated setup. For every 20⁰ phantom rotation, transverse group wave velocity measurements were performed with an Aixplorer Ultimate system and SL18–5 transducer using 0⁰/20⁰/−20⁰-angled ultrasound pushes. Transmural angular wave velocities were derived along 60⁰-trajectories. A 360⁰-angular velocity map was composed from the top-wall 60⁰-trajectories 0°-data, averaged over all physical phantom rotations (reference). For each phantom rotation, 360⁰-angular velocity maps were composed using 0°-data (0⁰-approach) or data from all angles (beam-steered approach). Percentages of rotations with visible waves and relative angular velocity errors compared to the reference map as function of the circumferential angle were determined for both approaches. ResultsReference 360°-angular velocity maps could be derived for all samples, representing their stiffness. Beam-steering decreased the proportion of the circumference where waves were untraceable by 20% in phantoms and 10% ex vivo, mainly at 0° push locations. Relative errors were similar for both approaches (phantoms: 10–15%, ex vivo: 15–35%). ConclusionBeam-steering enables wave-tracking along a higher proportion of the wall circumference than 0⁰ ARFI-induced wave-tracking.

Application of poly (vinyl alcohol)-cryogels to immobilizing nitrifiers: Enhanced tolerance to shear stress-induced destruction and viability control

The hardness of poly (vinyl alcohol)-cryogels (PVA-CGs) was improved under three parameter conditions: 7.5 %–12.5 % PVA, 1–5 freezing–thawing cycles (FTCs), and the addition of 0 %–10 % glycerol as a cryoprotectant. This study investigated the effects of shear stress-induced destruction (SSID) on mechanical strength by inducing rapid erosion with a high frictional force. Tolerance to SSID (Tol-SSID) exhibited different sensitivities and trends depending on the above three fabrication parameters. The measured Tol-SSID exhibited consistent and inconsistent trends with tensile strength and swelling, respectively. Tol-SSID evaluation provides new insights into the practically meaningful mechanical strength of PVA-CGs against strong friction, which simulates extreme shear stress in a bioreactor. A PVA-CG with a PVA concentration of 10 % and in two FTCs resulted in Tol-SSID and tensile strength of 88.3 % and 0.59 kPa, respectively. Here, 5 % glycerol was added to maintain the bacterial respiration activity of immobilized nitrifiers of 0.097 mg-O2/g-VSS·min and survival of 88.6 %. The continuous mode of nitrification using the optimized PVA-CG for 10 days resulted in an ammonia removal rate of 0.2173 kg-N/m3·d, which is an improvement over cases without glycerol addition: 0.1426 and 0.1472 kg-N/m3·d for PVA-CGs in two and three FTCs, respectively.

Synthesis of Biocompatible Composite Material Based on Cryogels of Polyvinyl Alcohol and Calcium Phosphates.

At the moment, the field of biomedical materials science is actively developing, which aims at creating new functional materials. A developing direction in biomedical materials science is that towards the treatment of diseases associated with bone tissue disorders, using biodegradable composite materials based on polymer and calcium phosphate materials. We developed a material based on polyvinyl alcohol cryogel, mineralized with calcium phosphate. A material based on cryogel of polyvinyl alcohol mineralized with calcium phosphate was developed. The composites were obtained by the method of cyclic freezing–thawing, and the synthesis of calcium phosphates was carried out in situ with heating, stirring, and exposure to microwave radiation. The phase composition, as well as the composition of functional groups, was determined by IR spectroscopy and X-ray phase analysis. Monocytes isolated from human blood showed higher viability compared to the controls.

NnUNet-based Multi-modality Breast MRI Segmentation and Tissue-Delineating Phantom for Robotic Tumor Surgery Planning.

Segmentation of the thoracic region and breast tissues is crucial for analyzing and diagnosing the presence of breast masses. This paper introduces a medical image segmentation architecture that aggregates two neural networks based on the state-of-the-art nnU-Net. Additionally, this study proposes a polyvinyl alcohol cryogel (PVA-C) breast phantom, based on its automated segmentation approach, to enable planning and navigation experiments for robotic breast surgery. The dataset consists of multimodality breast MRI of T2W and STIR images obtained from 10 patients. A statistical analysis of segmentation tasks emphasizes the Dice Similarity Coefficient (DSC), segmentation accuracy, sensitivity, and specificity. We first use a single class labeling to segment the breast region and then exploit it as an input for three-class labeling to segment fatty, fibroglandular (FGT), and tumorous tissues. The first network has a 0.95 DCS, while the second network has a 0.95, 0.83, and 0.41 for fat, FGT, and tumor classes, respectively. Clinical Relevance-This research is relevant to the breast surgery community as it establishes a deep learning-based (DL) algorithmic and phantomic foundation for surgical planning and navigation that will exploit preoperative multimodal MRI and intraoperative ultrasound to achieve highly cosmetic breast surgery. In addition, the planning and navigation will guide a robot that can cut, resect, bag, and grasp a tissue mass that encapsulates breast tumors and positive tissue margins. This image-guided robotic approach promises to potentiate the accuracy of breast surgeons and improve patient outcomes.

Characterization of blood-mimicking fluids for echocardiography imaging of ventricular septal defects.

Ventricular septal defects (VSD) are congenital heart malformations and, in severe cases, they require complex interventions under echocardiography guidance. Heart phantoms can be helpful to train and to understand the complex hemodynamics of VSD. The goal of this study was to characterize the best blood mimicking fluids in such heart phantoms for modelling the hemodynamics of VSD patients using echocardiography. Four fluid compositions were considered. Distilled water was used as a baseline, while the other three fluids were developed based on physical properties of human blood, such as the viscosity and the refractive index. Three bi-ventricular heart phantoms of three different pediatric patients with complex VSD were designed from preoperative CT imaging. Custom molds were printed in 3-D and the anatomical structure was casted in polyvinyl alcohol cryogel. The VSD in each heart phantom were observed using echocardiography and color Doppler imaging was used for the hemodynamic study. Heart phantoms with blood mimicking fluids of 30% glycerol and 27% glycerol, 10% sodium iodide were found to be anatomically realistic under echocardiography imaging. Hemodynamic parameters such as the pressure gradient and the volume of the shunt were characterized using color Doppler imaging. Proper composition of blood mimicking fluids are important for improving the realism in echocardiographic heart phantoms and they contribute to better understand the complex hemodynamic of VSD under echocardiography.