Multimodal guided wave inversion for arterial stiffness: methodology and validation in phantoms
Tuhin Roy, Matthew Urban, Yingzheng Xu, James Greenleaf and Murthy N Guddati
PUBLISHED IN: Institute of Physics and Engineering in Medicine, 2021
Arterial stiffness is an important biomarker for many cardiovascular diseases. Shear wave elastography is a recent technique aimed at estimating local arterial stiffness using guided wave inversion (GWI), i.e. matching the computed and measured wave dispersion. This paper develops and validates a new GWI approach by synthesizing various recent observations and algorithms: (a) refinements to signal processing to obtain more accurate experimental dispersion curves; (b) an efficient forward model to compute theoretical dispersion curves for immersed, incompressible cylindrical waveguides; (c) an optimization framework based on the recent observation that the measured dispersion curve is multimodal, i.e. it matches for not one but two different wave modes in two different frequency ranges. The resulting inversion approach is validated using extensive experimental data from rubber tube phantoms, not only for modulus estimation but also to simultaneously estimate modulus and wall thickness. The observations indicate that the modulus estimates are best performed with the information on wall thickness. The approach, which takes less than half a minute to run, is shown to be accurate, with the modulus estimated with less than 4% error for 70% of the experiments.
Related Scientific Publications
Current treatments for glioblastoma (GBM) face challenges due to rapidly occurring tumor recurrences. In response, researchers have developed localized drug delivery systems, notably AT101-GlioMesh - an alginate-based mesh embedded with AT101-loaded PLGA microspheres. Fabricated for high encapsulation efficiency, this system ensures a sustained release of AT101, demonstrating a significant cytotoxic effect on GBM cell lines. This promising development could potentially revolutionize GBM therapy and prevent tumor recurrence.
Polysaccharide-based hydrogels offer great promise in 3D bioprinting due to their biocompatibility and cellular response, but their poor mechanical properties often require extensive crosslinking. The solution? Enter thermoresponsive bioinks. This study examines a triad of carboxymethyl cellulose, agarose, and gelatin as a potential thermoresponsive ink, demonstrating that specific blends can form stable hydrogels with desirable mechanical and physical properties. The bioinks' cytotoxicity was assessed on two cell lines according to ISO 10993-5 standards, and successful printing of complex 3D patterns confirmed their printability.
Dense collagen matrices, crafted through automated gel aspiration-ejection (GAE), offer exciting potential in the field of biofabrication. This study illuminates the crucial role fibrillization pH plays in both the real-time rheological changes during collagen hydrogel gelation and the properties of the resulting biofabricated matrices. Findings demonstrate a relative increase in hydrogel stiffness with higher gelation pH, with matrices demonstrating increased fibrillar density, alignment, and micro-compressive modulus at specific pH levels. Importantly, these matrices showed low cell mortality when seeded with fibroblasts. These findings may offer valuable insights applicable to other hydrogel systems and biofabrication techniques.
Understanding the biomechanical properties of arteries is complex due to their cylindrical shape and waveguide behavior. This study provides valuable insights by utilizing three-dimensional measurements on an artery-mimicking tube in water, categorizing the tube wall motion into transient and steady state responses. The study's approach enables a more accurate estimation of the motion and improves our understanding of wave propagation in arterial walls, presenting significant opportunities for enhanced measurement of arterial mechanical properties.
Researchers have devised a method called '3D wet writing' to create small-diameter arterial conduits. This technique uses ionic gelation for fabricating customizable constructs quickly and without a template. The constructs show mechanical properties similar to native blood vessels and demonstrate biocompatibility, indicating their potential use as vascular constructs.
User Cytocompatibility, biocompatibility, and biodegradability are amongst the most desirable qualities of wound dressings and can be tuned during the bioplatform fabrication steps to enhance wound healing capabilities. A three-stepped approach (partial-crosslinking, freeze-drying, and pulverisation) was employed in fabricating a particulate, partially crosslinked (PC), and transferulic acid (TFA)-loaded chitosan-alginate (CS-Alg) interpolymer complex (IPC) with enhanced wound healing capabilities.