Annals of Biomedical Engineering最新文献

Purpose: Porcine cervical spines are commonly used as a surrogate for human lumbar spines due to their similar anatomic and mechanical characteristics. Despite their use in spinal biomechanics research, porcine annulus fibrosus (AF) yield and ultimate properties have not been fully evaluated. This study sought to provide a novel dataset of elastic, yield, and ultimate properties of the porcine AF loaded in the circumferential direction.

Methods: AF specimens were dissected from porcine cervical spines (C3/C4-C6/C7) oriented in the circumferential direction. Specimens were uniformly hydrated before being quasi-statically distracted to failure. Linear modulus, yield stress and strain, ultimate stress and strain, and ultimate strain energy density were calculated. Differences between spinal levels, circumferential regions, and radial regions were identified using multifactor ANOVA tests.

Results: AF specimens showed a regionally dependent response between outer and inner radial regions, but not between spinal level and circumferential region. The outer region was significantly stronger and stiffer than the inner regions. In both outer and inner tissue, mechanical yield occurred at approximately 80% of their ultimate properties.

Conclusion: This study generated a novel dataset of elastic, yield, and ultimate properties of the porcine AF. The data can be used in future research that requires a robust database of healthy, non-degenerated AF mechanical properties, such as the development of future finite-element models.

Purpose: Finite element simulations are an enticing tool to evaluate heart valve function; however, patient-specific simulations derived from 3D echocardiography are hampered by several technical challenges. The objective of this work is to develop an open-source method to enforce matching between finite element simulations and in vivo image-derived heart valve geometry in the absence of patient-specific material properties, leaflet thickness, and chordae tendineae structures.

Methods: We evaluate FEBio Finite Element Simulations with Shape Enforcement (FINESSE) using three synthetic test cases considering a range of model complexity. FINESSE is then used to estimate the in vivo valve behavior and leaflet strains for three pediatric patients.

Results: Our results suggest that FINESSE can be used to enforce finite element simulations to match an image-derived surface and estimate the first principal leaflet strains within $\pm 0.03$ strain. Key considerations include: (i) defining the user-defined penalty, (ii) omitting the leaflet commissures to improve simulation convergence, and (iii) emulating the chordae tendineae behavior via prescribed leaflet free edge motion or a chordae emulating force. In all patient-specific cases, FINESSE matched the target surface with median errors of approximately the smallest voxel dimension. Further analysis revealed valve-specific findings, such as the tricuspid valve leaflet strains of a 2-day old patient with HLHS being larger than those of two 13-year old patients.

Conclusions: FEBio FINESSE can be used to estimate patient-specific in vivo heart valve leaflet strains. The development of this open-source pipeline will enable future studies to begin linking in vivo leaflet mechanics with patient outcomes.

The primary objective of this study is to emphasize the importance of maintaining optimal oral health through regular toothbrushing practices. To achieve this objective, a custom-designed electromechanical toothbrush simulator device was developed. This innovative tool enables researchers to investigate the impact of abrasive-based whitening toothpastes on enamel surface roughness compared to brushing without toothpaste. The device design is composed of multiple systems, including mechanical, motorization, and toothpaste irrigation components. The device incorporates various components, including mechanical, motorization, and toothpaste irrigation systems. Specifically, the mechanical aspect comprises fabricated metal parts, 3D printed elements, and a load cell for measuring brushing force. The motorization section integrates a microcontroller and a stepper motor, allowing for the adjustment of brushing cycles and speed. Furthermore, the toothpaste irrigation system employs a pump with adjustable speed, along with a toothpaste canister and a waste receptacle. By providing a controlled environment for evaluating the effects of different toothpaste formulations on enamel integrity, this simulator device contributes significantly to advancements in oral care research and product development.

Purpose: Arteriovenous fistula (AVF), the preferred vascular access for hemodialysis, is associated with high failure rate. The aim of this study was to investigate the potential of AVF sound auscultation in providing quantitative information on AVF hemodynamic conditions.

Methods: This single-center prospective study involved six patients with native radio-cephalic AVFs who underwent multiple follow-up visits. Doppler Ultrasound blood flow volume (BFV) assessment and electronic stethoscope-based sound recordings were performed during each visit, whereas MRIs were acquired 3 days, 3 weeks and 1 year after surgery. Computational fluid dynamic (CFD) simulations were performed on patient-specific MRI-derived geometrical models.

Results: Higher values of median peak amplitudes ratios (high-low peak ratio-HLPR) were found to be associated with complex blood flow and velocity streamlines recirculation at systolic peak, and corresponding extended regions of high oscillatory shear index (OSI). On the contrary, lower values of HLPR were associated with laminar flow pattern and low values of OSI. Significant differences were observed in HLPR between subgroups with extended or limited areas with OSI > 0.1 (0.67 vs 0.31, respectively). Significant relationships were found between AVF sound intensity and brachial BFV (slope = 0.103, p < 0.01) as well as between longitudinal changes in brachial BFV and HLPR (slope = - 0.001, p < 0.01).

Conclusion: Our results show that AVF sound can be exploited to extract fundamental information on AVF hemodynamic conditions, providing indication of the presence of complex hemodynamic and adequate BFV to perform hemodialysis. Sound analysis has therefore the potential to improve clinical AVF surveillance and to ameliorate outcome.

The Fontan procedure is the definitive palliation for pediatric patients born with single ventricles. Surgical planning for the Fontan procedure has emerged as a promising vehicle toward optimizing outcomes, where pre-operative measurements are used prospectively as post-operative boundary conditions for simulation. Nevertheless, actual post-operative measurements can be very different from pre-operative states, which raises questions for the accuracy of surgical planning. The goal of this study is to apply machine leaning techniques to describing pre-operative and post-operative vena caval flow conditions in Fontan patients in order to develop predictions of post-operative boundary conditions to be used in surgical planning. Based on a virtual cohort synthesized by lumped-parameter models, we proposed a novel diversity-aware generative adversarial active learning framework to successfully train predictive deep neural networks on very limited amount of cases that are generally faced by cardiovascular studies. Results of 14 groups of experiments uniquely combining different data query strategies, metrics, and data augmentation options with generative adversarial networks demonstrated that the highest overall prediction accuracy and coefficient of determination were exhibited by the proposed method. This framework serves as a first step toward deep learning for cardiovascular flow prediction/regression with reduced labeling requirements and augmented learning space.

Purpose: The risk of submarining during automotive crashes, defined by the lap belt sliding off the pelvis to load the abdomen, is predicted to increase in future autonomous vehicles as greater variation in seating position is enabled. Biofidelic tools are required to efficiently design and evaluate new and/or improved safety systems. This study aims to evaluate the pelvis response sensitivity to variations in boundary conditions that directly influence the pelvis loads, deemed important for the submarining outcome, to facilitate a more precise comparison between finite element human body models (FE-HBMs) and post-mortem human subjects (PMHSs).

Methods: A parameter study, using a one-variable-at-a-time analysis (low/high) of belt friction, seat friction, seat stiffness, and (on/off) for added belt bending stiffness, was performed using a state-of-the-art FE-HBM in four different test scenarios; one stationary, two sleds with upright occupant posture, and one sled with reclined occupant posture.

Results: In the stationary scenario, both belt friction and belt bending stiffness influenced the belt folding behavior, which consequently affected the belt-to-pelvis angle at submarining. In the sled scenarios, only seat friction was found to influence the pelvis kinematics and submarining outcome, with the most biofidelic response resulting from both the low (0.2) and high (0.5) friction coefficient depending on the scenario.

Conclusion: To reduce uncertainty in boundary conditions affecting the external pelvis loads and increase confidence in FE-HBM to PMHS comparisons, it is recommended that future experiments evaluate the PMHS to seat friction coefficient and that new belt modeling methods that accurately capture belt folding when interacting with soft tissues are developed.

Purpose: Understanding how spinal orientation affects injury outcome is essential to understand lumbar injury biomechanics associated with high-rate vertical loading.

Methods: Whole-column human lumbar spines (T12-L5) were dynamically loaded using a drop tower to simulate peak axial forces associated with high-speed aircraft ejections and helicopter crashes. Spines were allowed to maintain natural lordotic curvature for loading, resulting in a range of orientations. Pre-test X-rays were used to quantify specimen orientation at the time of loading. Primary fracture types were identified (wedge, n = 6; burst, n = 4; hyperextension, n = 4) and compared for loading parameters and lumbar orientation.

Results: Fracture type was dependent on peak acceleration, bending moment, Cobb angle, sagittal spinal tilt, and location of the applied load.

Conclusions: Lumbar spine orientation under high-rate axial acceleration affected the resulting fracture type. Analysis of pre-test X-rays revealed that spines that sustained wedge and burst fractures were oriented straighter at the time of loading. The load was applied centrally to T12 in spines with burst fractures, and anteriorly to T12 in spines with wedge fractures. Spines that sustained hyperextension fracture had lower peak accelerations, larger Cobb angles at the time of loading, and sustained larger extension moments. Fracture presentation is an important and understudied factor that influences biomechanical stability, clinical course, and long-term patient outcomes.

Purpose: This study addresses the critical issue of evaluating the risk of rupture of unruptured intracranial aneurysms (UIAs) through the assessment of the mechanical properties of the aneurysm wall. To achieve this, an original approach based on the development of an in vivo deformation device prototype (DDP) of the vascular wall is proposed. The DDP operates by pulsing a physiological fluid onto the vascular wall and measuring the resulting deformation using spectral photon counting computed tomography (SPCCT) imaging.

Methods: In this preliminary study conducted on a rabbit animal model, an aneurysm was induced on the carotid artery, followed by deformation of the aneurysm sac wall using the DDP. The change in luminal volume of the aneurysm sac induced by the deformation of the vascular wall was then quantified.

Results: The initial experimental results demonstrated an increase in the luminal volume of the aneurysm sac in relation to the increased flow rate of the fluid pulsed by the DDP onto the arterial wall. Measurement of the pressure generated by the DDP in relation to the different flow rate values imposed by the pulsation system revealed experimental values of the same order of magnitude as dynamic blood pressure. Furthermore, theoretical pressure values on the deformed area, calculated using Euler's theorem, appeared to be correlated with experimental pressure measurements.

Conclusion: This equivalence between theory and experiment is a key element in the use of the DDP for estimating the mechanical properties of the vascular wall, particularly for the use of finite element models to characterise the stress state of the deformed vascular wall. This preliminary work thus presents a novel, innovative, and promising approach for the evaluation and management of the risk of rupture of unruptured intracranial aneurysms.

The development of cardiovascular implants is abundant, yet their clinical adoption remains a significant challenge in the treatment of valvular diseases. Tissue-engineered heart valves (TEHV) have emerged as a promising solution due to their remodeling capabilities, which have been extensively studied in recent years. However, ensuring reproducible production and clinical translation of TEHV requires robust longitudinal monitoring methods.Cardiovascular magnetic resonance imaging (MRI) is a non-invasive, radiation-free technique providing detailed valvular imaging and functional assessment. To facilitate this, we designed a state-of-the-art metal-free bioreactor enabling dynamic MRI and ultrasound imaging. Our compact bioreactor, tailored to fit a 72 mm bore 7 T MRI coil, features an integrated backflow design ensuring MRI compatibility. A pneumatic drive system operates the bioreactor, minimizing potential MRI interference. The bioreactor was digitally designed and constructed using polymethyl methacrylate, utilizing only polyether ether ketone screws for secure fastening. Our biohybrid TEHV incorporates a non-degradable polyethylene terephthalate textile scaffold with fibrin matrix hydrogel and human arterial smooth muscle cells.As a result, the bioreactor was successfully proven to be MRI compatible, with no blooming artifacts detected. The dynamic movement of the TEHVs was observed using gated MRI motion artifact compensation and ultrasound imaging techniques. In addition, the conditioning of TEHVs in the bioreactor enhanced ECM production. Immunohistology demonstrated abundant collagen, α-smooth muscle actin, and a monolayer of endothelial cells throughout the valve cusp. Our innovative methodology provides a physiologically relevant environment for TEHV conditioning and development, enabling accurate monitoring and assessment of functionality, thus accelerating clinical acceptance.

The functional and structural integrity of the tissue/organ can be compromised in multilayer reconstructive applications involving cartilage tissue. Therefore, multilayer structures are needed for cartilage applications. In this review, we have examined multilayer scaffolds for use in the treatment of damage to organs such as the trachea, joint, nose, and ear, including the multilayer cartilage structure, but we have generally seen that they have potential applications in trachea and joint regeneration. In conclusion, when the existing studies are examined, the results are promising for the trachea and joint connections, but are still limited for the nasal and ear. It may have promising implications in the future in terms of reducing the invasiveness of existing grafting techniques used in the reconstruction of tissues with multilayered layers.