Biology subjects

Ahmed, D.

Publications and source records attributed to Ahmed, D..

At least 19 recordsLinked to original sources

bioRxiv2026

MicroDLP: Microscope-Enabled Resolution-Switchable 3D Microprinting

Complex three-dimensional (3D) microarchitectures are increasingly important for microfluidics, microrobotics, organ-on-chip systems, biomedical devices, and architected materials. However, fabricating complex 3D microstructures with micrometre-scale precision remains a major manufacturing challenge. Integrating these fine features with larger supporting structures presents an additional challenge, requiring fabrication across multiple length scales within a single architecture. Although microscale 3D printing enables intricate geometries, the trade-off between resolution and build volume limits multiscale fabrication, while existing approaches often require complex optics and precise registration. Here, we introduce MicroDLP, a microscope-enabled digital light processing platform for versatile, resolution-switchable 3D microprinting. By integrating a projection module into a conventional inverted microscope, MicroDLP exploits its revolving objective turret to switch between 4x, 10x, and 20x objectives, providing projected pixel sizes from 1.89 to 0.378 um. We characterize photopolymerization, voxel geometry, and lateral feature resolution across magnifications to establish suitable microscale printing conditions. MicroDLP enables the fabrication of diverse and complex 3D microarchitectures, including freestanding trusses with 170 um struts, microvascular structures with 10 um features, interlocking gears, suspended microbridges, and microneedles with 3-5 um tips. Importantly, switching from 10x to 20x during fabrication produces monolithic 3D structures combining larger supporting foundations with fine micropillar arrays, without manual optical realignment. The shared optical pathway also enables coaxial in situ monitoring of photopolymerization. Together, these results establish MicroDLP as a versatile platform for microscale additive manufacturing, combining complex 3D microfabrication with resolution switching within a single monolithic structure.

bioengineering↗

bioRxiv2026

Physiological robustness of MScanFit to simulated motor unit loss and remodelling

Introduction: MScanFit estimates motor unit number and size from compound muscle action potential (CMAP) scans, but its accuracy may depend on the physiological processes that shape motor unit loss and remodelling. We reproduced the general dynamic remodelling framework used in the original MScanFit simulation and expanded it to test MScanFit robustness across physiologically heterogeneous conditions. Methods: Generative computational models simulated CMAP scans from motor unit pools undergoing progressive loss from 160 to 5 surviving motor units. Twelve remodelling conditions combined denervation pattern (random or selective), reinnervation method (random, distributive, or size-weighted), and neuromuscular resilience (20% or 60%); two additional conditions modelled denervation without collateral reinnervation. MScanFit estimates were compared with the known motor unit numbers and mean motor unit sizes used to generate each scan. Results: MScanFit reproduced the principal behaviour reported in the original simulation and generally tracked progressive motor unit loss across heterogeneous remodelling conditions. However, motor unit number estimation (MUNE) error changed systematically with remodelling physiology. Selective denervation and distributive reinnervation increased error at several intermediate stages of motor unit loss, whereas 60% resilience produced greater error than 20% resilience at every stage after remodelling began. Motor unit size estimates also tracked the underlying increase in mean unit size, but their accuracy was more strongly affected by remodelling, particularly with 60% resilience and advanced motor unit loss. Conclusion: MScanFit motor unit number estimates were broadly robust to substantial motor unit loss and neuromuscular remodelling but were not physiologically invariant. Denervation and collateral reinnervation systematically influenced the magnitude and direction of estimation error, indicating that variation in MScanFit performance can arise from differences in the underlying motor unit population. These findings support MScanFit as a robust measure of motor unit loss across heterogeneous neuromuscular phenotypes and show that some of its estimation variability has a physiological basis.

neuroscience↗

bioRxiv2026

Reprogrammed neutrophils with impaired transit mechanics drive multi-organ capillary stalling after stroke

Beyond the focal brain lesion, stroke causes systemic complications including cardiac failure, pneumonia, renal injury, and sustained immune dysfunction. The source of this multiorgan vulnerability remains unresolved. By imaging over 16,000 vessels of healthy, inflamed and ischemic brains, we identify a circulating neutrophil subpopulation reprogrammed by stroke into a pathological stalling phenotype, occluding capillaries in the brain, heart, kidneys, retina and lungs. Combining transcriptomics, genetic models, integrated microfluidics, cell mechanics assays, and in vivo imaging, we show that this subpopulation exhibits an atypical morphology, increased actin polymerization, and heightened adhesion that impair transit through capillary networks. This phenotype is present in patients with stroke, transmissible by adoptive transfer, and selectively sensitive to inhibition of the Src-family kinase Fgr. Both pharmacological and genetic inactivation of Fgr normalize neutrophil adhesion, reduce capillary stalls, and improve neurological recovery after stroke. These findings identify immune cell transit failure as a systemic driver of post-stroke pathology and a therapeutic target to improve both cerebral and multiorgan outcomes.

neuroscience↗

bioRxiv2025

Nucleic acid strand length governs mitochondrial reprogramming and mtROS-associated antiviral responses following TLR3 engagement

Mitochondria are important rheostats that regulate innate sensing processes by producing energy, biosynthetic precursors, and bioactive molecules that affect cellular signaling. When viral nucleic acids engage endosomal and cytosolic pattern recognition receptors (PRR), antiviral immune responses are supported by mitochondrial remodeling but the role of mitochondria in fine tuning ligand-specific responses remains incompletely understood. For example, endosomal TLR3 can detect various lengths of dsRNA (0.4-8 kb) ranging from viral segmented genomes or endogenous nucleic acids have been shown to induce distinct cytokine profiles. However, it is unclear if these differences are associated with differential mitochondrial remodeling. Here, we report that TLR3 engagement with both high (HMW; 1.5-8 kb) or low molecular weight (LMW; 0.2-1 kb) Polyinosinic:polycytidylic acid (Poly(I:C)) is associated with reduced but sustained oxidative phosphorylation (OXPHOS) activity and increased mitochondrial reactive oxygen species (mtROS) production/accumulation to support antiviral responses in bone marrow-derived macrophages (BMDM). They differed in the amount of mtROS production, their spare respiratory capacity (SRC) and their mitochondrial membrane potential (MMP). Interestingly, while uncoupling protein 2 (UCP2) was found required for antiviral cytokine production, it did not contribute to ligand specific responses. Dynamic modulation of complex I of the electron transport chain (ETC), however resulted in the differential accumulation of mtROS (HMW>LMW). Further, selectively targeting the mtROS derived from Complex I leads to augmented type I IFN production. Overall, these findings highlight that targeting specific sources of mtROS without affecting electron flow may be a potential avenue for specific augmentation of antiviral responses during viral infections.

immunology↗

bioRxiv2025

Ultrasound-induced Particle Dynamics in Pathological Vascular Vortices

Disturbed flow is a hallmark of diseased vasculature, yet its influence on particle behavior under external actuation remains poorly understood. We uncover distinct behaviors of microparticles under disturbed flow when exposed to ultrasound, revealing selective trapping and aggregation phenomena that differ fundamentally between soft and rigid particles. Using microfluidic models of disturbed vascular flow, we show that microbubbles become trapped at the eye of vortices and self-assemble via ultrasound-induced forces. As clusters grow to a critical size, they are ejected and adhere to the wall opposite the ultrasound source, forming nuclei that progressively occupy aneurysm cavities--a mechanism that could enable targeted, noninvasive treatment. These findings reveal an unexplored interplay between ultrasound and hydrodynamic forces, offering a new strategy for ultrasound-guided therapeutic delivery in vascular disease. One-Sentence SummaryVortices are common in diseased arteries, yet we dont know how therapeutic carriers behave in them under ultrasound. We discover that microbubbles self-assemble in vortex cores, then eject and anchor to vessel walls--revealing a new transport regime with therapeutic potential.

bioengineering↗

bioRxiv2025

Bioinspired Geometry-Encoded Rheotactic Navigation of Sound-Driven Microrobots

Imitating the shape-encoded tactics of natural microswimmers--organisms that flip, roll, and rheotaxis through viscous fluids--could transform microfluidics, micromanufacturing, and targeted therapy. However, translating those geometric navigation cues into actively driven microrobots is an open, largely unexplored challenge. Here, inspired by the structure of sperm cells, we introduce a sound-propelled head-helix microparticle ("microrobot") featuring an elliptical head and a spiral tail. This asymmetrical design interacts with the incident acoustic field, generating complex secondary flows that induce a torque, enabling the particle to reorient around its cross-section. The microparticle exhibits a preferred direction of propulsion and orientation when exposed to a traveling sound wave, reorienting if its initial alignment deviates from this preference. Both the preferred direction and orientation can be modulated by adjusting the sound frequency, and they further adapt to background flow fields in the environment. Furthermore, the microparticle exhibits rheotaxis-like motion, exhibiting wall-following motion with frequency-dependent sliding behavior. By moving towards the channel wall, it enters the region with the smallest flow velocities, allowing it to move antiparallel to the fluid. These findings contribute to the engineering of the trajectories of sound-propelled microparticles and to the development of next-generation microrobots for medical and other innovative applications.

bioengineering↗

bioRxiv2025

Bio-Inspired Ultrasound-Driven Ultrafast Soft Microgripper

Acoustically actuated soft matter offers potential for agile microscale manipulation, yet acoustic-soft matter interaction at the microscale remains poorly understood. Here, we explore the mechanism of ultrasound-soft matter interaction by developing a bio-inspired ultrasound-driven soft hydrogel microgripper. This exploration allows to delve deeper into the understanding of nonlinear dynamics, mode coupling, and energy transfer. The developed microgripper ([≤] 120 {micro}m) overcomes key challenges of existing grippers, including complex fabrication, reliance on additives or external wiring, rigid structures, slow or poorly controllable responses, and risks of sample damage or contamination. Interacting with acoustic actuation, soft microgrippers oscillate and deform, while adjusting acoustic parameters and microgrippers structures allows for programmable interactions. The optimized acoustic actuation of the soft microgripper enables precise, ultrafast ([~]2 ms) gripping and handling of distinct delicate objects. This work advances the integration of soft matter with acoustic actuation especially at the microscale, offering a versatile, reliable, and scalable solution for microrobotics, targeted drug delivery, and lab-on-a-chip applications. TeaserAcoustic-soft matter interaction validated on bio-inspired ultrasound-driven ultrafast soft microgrippers.

bioengineering↗

bioRxiv2025

Going green: Recycling transcriptomes to infer evolutionary relationships, gene duplication, gene tree conflict, and patterns of molecular evolution in the Apocynaceae

Background and AimsThe flowering plant family Apocynaceae exhibits diverse adaptations with biological and pharmaceutical significance, many of which have been studied with RNA-seq. However, despite the available transcriptomic data, no focused phylotranscriptomic study has been conducted to characterize the patterns of molecular evolution in this group. In this study, we leverage a dataset composed predominately of publicly available transcriptomes to infer relationships within Apocynaceae and explore the molecular processes that have shaped their divergences. MethodsWe extracted nuclear, chloroplast, and mitochondrial genes from 47 publicly available and one newly sequenced transcriptome to assemble and infer species relationships across Apocynaceae. Leveraging the gene-rich nuclear phylotranscriptomic data, we inferred molecular dates and investigated the complex history of gene tree conflict, molecular rate shifts, and gene duplications. To investigate the genomic basis of adaptations, we analyzed the inferred 14,838 gene duplications at the base of Apocynaceae for shared functional enrichment of genes related to evolutionary innovations. Key ResultsThe Apocynaceae topology inferred from our phylotranscriptomic analysis is highly concordant with the current consensus. Notably, a genome-wide acceleration in molecular rate subtends the Ceropegieae tribe. We observed that a decreased time between divergences is associated with a higher rate of gene tree conflict, a pattern especially prevalent across the Apocynaceaes historically recalcitrant backbone relationships. Furthermore, gene duplications may underlie evolutionary innovations, such as immunity-related gene expansion in the genus Asclepias and duplications associated with trichome modifications in the epiphytic Hoya. Finally, we discuss the contentious history of whole-genome duplication (WGD) within the Apocynaceae and emphasize the need for further investigation into the placement of WGDs. ConclusionsRepurposing transcriptomes is a powerful means of accumulating data for novel insights in plant evolution, especially during uncertain funding and cases where budget restrictions exist. Leveraging this gene-dense dataset, we obtained novel insights into the molecular evolution of Apocynaceae and identified areas for future investigations.

evolutionary biology↗

bioRxiv2025

KODAMA enables self-guided weakly supervised learning in spatial transcriptomics

Spatial transcriptomics provides researchers with a powerful tool to investigate gene expression patterns within their native positional context in tissues, revealing intricate cellular relationships. However, analyzing spatial transcriptomics data presents unique challenges due to their high dimensionality and complexity. Several competitive tools have emerged, each aiming to integrate spatial dependencies into their workflow. Yet, the overall performance of these approaches remains constrained by limitations in prediction accuracy and compatibility with specific data types. Here, we introduce the third version of the KODAMA algorithm, specifically tailored for spatial transcriptomics analysis. This upgraded version incorporates a novel approach that effectively reduces data dimensionality while preserving spatial information. At its core, the KODAMA algorithm employs parallel iterations that enforce spatial constraints throughout an embedded clustering process. Our method provides the flexibility to simultaneously analyze multiple samples, streamlining analysis workflows. Additionally, it extends beyond traditional 2D analysis to accommodate multidimensional datasets, including 3D spatial information. KODAMA seamlessly integrates into various pipelines, such as Seurat and Giotto. Extensive evaluations of KODAMA on 10x Visium, Visium HD, and image-based 3D datasets demonstrate its high accuracy in spatial domain prediction. Comparative analyses against alternative dimensionality reduction techniques and spatial analysis tools consistently validate and highlight KODAMAs superior performance in unraveling the spatial organization of cellular components across both single and integrated tissue samples.

bioinformatics↗

bioRxiv2025

Real-time Color Flow Mapping of Ultrasound Microrobots

Visualization and tracking of microrobots in real-time pose key challenges for surgical microrobotic systems, as existing imaging modalities like MRI, CT, and X-ray are unable to monitor microscale items with real-time resolution. Ultrasound imaging-guided drug administration represents a significant advancement in this respect, offering real-time visual feedback on invasive medical procedures. However, ultrasound imaging still faces substantial inherent limitations in spatial resolution and signal attenuation, which hinder extending this method to microrobot visualization. Here, we introduce an approach for visualizing individual microrobots in real-time with Color Flow Mapping ultrasound imaging, based on acoustically induced structural oscillations of the microrobot generating a pseudo-Doppler signal. This approach enables the simultaneous localization and activation of bubble-based microrobots using two ultrasound sources operating at distinct frequency bandwidths. Our successful capture of microrobots measuring 60-80 micrometers in diameter reveals the potential of real-time ultrasonic imaging at the microscale. One-sentence SummaryAdvancing ultrasound imaging for real-time, microscale visualization--a critical breakthrough for therapeutic microrobots.

bioengineering↗

bioRxiv2025

Programmable Assembly and Steering of Microbubble Droplets using Ultrasound

Gas-filled microbubbles have been extensively used as contrast agents for ultrasound therapies and have recently been explored as microrobots. When exposed to an intense acoustic wave, microbubbles oscillate and scatter the sound field, leading to assembly and manipulation behaviors. Although traditional microbubbles demonstrated promising potential for manipulation in physiological environments, we recognized the need for improved assembly selectivity and acoustically directed propulsion. For this, we developed a new microbubble design using microfluidics. We engineered microbubbles with an outer oil droplet encapsulating a gas core, allowing the gas to move freely within the oil. When the gas reaches the droplets periphery, the oil attenuates the scattered wave, ensuring that scattering or acoustic amplification is concentrated near the droplets edge. This approach enabled us to control the organized assembly of microbubbles and direct their acoustic navigation. We believe this approach will open new possibilities for using gas-filled microbubbles as safer drug carriers or for micro-interventions in biomedical settings.

bioengineering↗

bioRxiv2024

Model-Based Reinforcement Learning for Ultrasound-Driven Autonomous Microrobots

AI has catalyzed transformative advancements across multiple sectors, from medical diagnostics to autonomous vehicles, enhancing precision and efficiency. As it ventures into microrobotics, AI offer innovative solutions to the formidable challenge of controlling and manipulating microrobots, which typically operate within imprecise, remotely actuated systems--a task often too complex for human operators. We implement state-of-the-art model-based reinforcement learning for autonomous control of an ultrasound-driven microrobot learning from recurrent imagined environments. Our non-invasive, AI-controlled microrobot offers precise propulsion, which efficiently learns from images in data-scarce environments. Transitioning from a pre-trained simulation environment, we achieve sample-efficient collision avoidance and channel navigation, reaching a 90% success rate in target navigation across various channels within an hour of fine-tuning. Moreover, our model initially successfully generalized in 50% of tasks in new environments, improving to over 90% with 30 minutes of further training. Furthermore, we have showcased real-time manipulation of microrobots within complex vasculatures and across stationary and physiological flows, underscoring AIs potential to revolutionize microrobotics in biomedical applications, potentially transforming medical procedures.

bioengineering↗

bioRxiv2024

Magnetoelectric Microrobots for Spinal Cord Injury Regeneration

Regenerative medicine continually seeks effective methods to address spinal cord injuries (SCI), which are known for their limited regenerative potential. Despite advances in neural progenitor cell (NPC) transplants for spinal cord injuries, challenges related to graft survival, reliable in vivo differentiation, and neural integration significantly hinder real functional recovery and limit clinical outcomes. This study introduces NPCbots, biohybrid microrobots engineered by integrating human-induced pluripotent stem cell-derived NPCs with magnetoelectric nanoparticles composed of cobalt ferrite-barium titanate. These enable magnetic navigation and neuronal stimulation, enhancing targeted therapeutic interventions. Our lab-on-a-chip system allows for the mass production of NPCbots, ensuring their differentiation and biocompatibility. Remarkably, in a zebrafish model of SCI, NPCbots stimulated by an alternating magnetic field demonstrated rapid in vivo differentiation and integration into damaged neural pathways, significantly enhancing neural regeneration. Within three days, injured zebrafish treated with NPCbots exhibited almost normal swimming behavior and significantly improved exploratory behavior, showcasing the potential of NPCbots to swiftly repair neural structures and restore the central nervous systems functionality in spinal cord injury models through non-invasive means. Additionally, precise in vitro and in vivo manipulation of NPCbots indicates their broader application in various neurodegenerative disorders, offering a promising route for effective spinal cord and neurological recovery.

neuroscience↗

bioRxiv2024

Ultrasound-Driven Programmable Artificial Muscles

Muscular systems1, the fundamental components of mobility in animals, have sparked innovations across technological and medical fields2,3. Yet artificial muscles suffer from dynamic programmability, scalability, and responsiveness due to complex actuation mechanisms and demanding material requirements. Here, we introduce a design paradigm for artificial muscles, utilizing >10,000 microbubbles with targeted ultrasound activation. These microbubbles are engineered with precise dimensions that correspond to distinct resonance frequencies. When stimulated by a sweeping-frequency ultrasound, microbubble arrays in the artificial muscle undergo selective oscillations and generate distributed point thrusts, enabling the muscle to achieve programmable deformation with remarkable attributes: a high compactness of [~]3,000 microbubbles/mm{superscript 2}, a low weight of 0.047 mg/mm2, a substantial force intensity of [~]1.21 N/mm2, and fast response (sub-100 ms during gripping). Moreover, they offer good scalability (from micro- to -centimeter scale), exceptional compliance, and many degrees of freedom. We support our approach with a theoretical model and demonstrate applications spanning flexible organism manipulation, conformable robotic skins for adding mobility to static objects and conformally attach to ex vivo porcine organs, and biomimetic stingraybots for propulsion within ex vivo biological environments. The customizable artificial muscles could offer both immediate and long-term impact on soft robotics, wearable technologies, haptics, and biomedical instrumentation.

bioengineering↗

bioRxiv2023

SonoPrint: Acoustically Assisted Volumetric 3D Printing for Composites

Advancements in additive manufacturing in composites have transformed various fields in aerospace, medical devices, tissue engineering, and electronics, enabling fine-tuning material properties by reinforcing internal particles and adjusting their type, orientation, and volume fraction. This capability opens new possibilities for tailoring materials to specific applications and optimizing the performance of 3D-printed objects. Existing reinforcement strategies are restricted to pattern types, alignment areas, and particle characteristics. Alternatively, acoustics provide versatility by controlling particles independent of their size, geometry, and charge and can create intricate pattern formations. Despite the potential of acoustics in most 3D printing, limitation arises from the scattering of the acoustic field between the polymerized hard layers and the unpolymerized resin, leading to undesirable patterning formation. However, this challenge can be addressed by adopting a novel approach that involves simultaneous reinforcement and printing the entire structure. Here, we present SonoPrint, an acoustically-assisted volumetric 3D printer that produces mechanically tunable composite geometries by patterning reinforcement microparticles within the fabricated structure. SonoPrint creates a standing wave field that produces a targeted particle motif in the photosensitive resin while simultaneously printing the object in just a few minutes. We have also demonstrated various patterning configurations such as lines, radial lines, circles, rhombuses, quadrilaterals, and hexagons using microscopic particles such as glass, metal, and polystyrene particles. Furthermore, we fabricated diverse composites using different resins, achieving 87 microns feature size. We have shown that the printed structure with patterned microparticles increased their tensile and compression strength by [~]38% and [~]75%, respectively.

bioengineering↗

bioRxiv2023

Multiplexed functional assessments of MYH7 variants in human cardiomyocytes at scale

BackgroundSingle, autosomal-dominant missense mutations in MYH7, which encodes a sarcomeric protein (MHC-{beta}) in cardiac and skeletal myocytes, are a leading cause of hypertrophic cardiomyopathy and are clinically-actionable. However, [~]75% of MYH7 variants are of unknown significance (VUS), causing diagnostic challenges for clinicians and emotional distress for patients. Deep mutational scans (DMS) can determine variant effect at scale, but have only been utilized in easily-editable cell lines. While human induced pluripotent stem cells (hiPSCs) can be differentiated to numerous cell types that enable the interrogation of variant effect in a disease-relevant context, DMS have not been executed using diploid hiPSC derivates. However, CRaTER enrichment has recently enabled the pooled generation of a saturated five position MYH7 variant hiPSC library suitable for DMS for the first time. ResultsAs a proof-of-concept, we differentiated this MYH7 variant hiPSC library to cardiomyocytes (hiPSC-CMs) for multiplexed assessment of MHC-{beta} variant abundance by massively parallel sequencing (VAMP-seq) and hiPSC-CM survival. We confirm MHC-{beta} protein loss occurs in a failing human heart with a pathogenic MYH7 mutation. We find the multiplexed assessment of MHC-{beta} abundance and hiPSC-CM survival both accurately segregate all pathogenic variants from synonymous controls. Overall, functional scores of 68 amino acid substitutions across these independent assays are [~]50% consistent. ConclusionsThis study leverages hiPSC differentiation into disease-relevant cardiomyocytes to enable multiplexed assessments of MYH7 missense variants at scale for the first time. This proof-of-concept demonstrates the ability to DMS previously restricted, clinically-actionable genes to reduce the burden of VUS on patients and clinicians.

genetics↗

bioRxiv2023

An Acoustically Controlled Microrobot Modelled on Spirochete Bacteria

As a next-generation toolkit, microrobots can transform a wide range of fields, including micromanufacturing, electronics, microfluidics, tissue engineering, and medicine. While still in their infancy, acoustically actuated wireless microrobots are becoming increasingly attractive, as acoustic control can generate large propulsive forces, requires relatively simple microrobot design, and does not entail complex manipulation systems. However, the interaction of acoustics with microstructure geometry is poorly understood to date, and its study is necessary for developing next-generation acoustically powered microrobots. We present here a mass-manufactured acoustically driven helical microrobot capable of locomotion using a fin-like double-helix microstructure. This microrobot responds to sound stimuli and mimics the spiral motion of natural microswimmers such as spirochetes. The asymmetric double helix interacts with the incident acoustic field, inducing a propulsion torque that causes the microrobot to rotate around its long axis. Moreover, our microrobot has the unique feature of its directionality being switchable by simply tuning the acoustic frequency. We demonstrate this locomotion in 2D and 3D artificial vasculatures using a single sound source. Since ultrasound is widely used as an imaging modality in clinical settings, our robotic system can integrate seamlessly into practice; thus, our findings could contribute to the development of next-generation smart microrobots. One-Sentence SummaryWe present an acoustically driven helical microrobot capable of corkscrew-like locomotion using a double-helix microstructure.

bioengineering↗

bioRxiv2023

The impact of patient-specific inlet conditions on oscillatory shear and helicity in haemodynamic simulations of aneurysmal Type-B Aortic Dissection

Type-B Aortic Dissection is a cardiovascular disease in which a tear develops in the intimal layer of the descending aorta, allowing pressurized blood to delaminate the layers of the vessel wall. In medically managed patients, long-term aneurysmal dilatation of the false lumen (FL) is considered virtually inevitable and is associated with poorer disease outcomes. While the pathophysiological mechanisms driving FL dilatation are not yet understood, hemodynamic factors are believed to play a key role. Computational Fluid Dynamics (CFD) and 4D-Flow MRI (4DMR) analyses have revealed correlations between flow helicity, oscillatory wall shear stress, and aneurysmal dilatation of the FL. In this study, we compare CFD simulations using a patient-specific, three-dimensional, three-component inlet velocity profile (3D IVP) extracted from 4DMR data against simulations with flow rate-matched uniform and axial velocity profiles that remain widely used in the absence of 4DMR. We also evaluate the influence of measurement errors in 4DMR data by scaling the 3D IVP to the degree of imaging error detected in prior studies. We observe that oscillatory shear and helicity are highly sensitive to inlet velocity distribution and flow volume throughout the FL and conclude that the choice of IVP may greatly affect the future clinical value of simulations.

bioengineering↗