Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session X03: Cardiac Flows II |
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Chair: Juan Carlos, University of Washington Room: Ballroom C |
Tuesday, November 26, 2024 8:00AM - 8:13AM |
X03.00001: Input-Parameterized Physics-Informed Neural Networks for Time-Resolved 3D Blood Flow Velocity Reconstruction and Wall Shear Stress Calculation Using Data from Modified 2D PCMRI Amin Pashaei Kalajahi, Omid Amili, Amirhossein Arzani, Roshan M D'Souza Two-dimensional phase-contrast magnetic resonance imaging (2D PCMRI) quantifies velocity in a single imaging plane with unidirectional velocity encoding. To accurately measure velocity, the imaging plane must be positioned perpendicular to the blood vessel's centerline, requiring slice selection and adjusting the magnitude of bipolar gradients in the directional coils. |
Tuesday, November 26, 2024 8:13AM - 8:26AM |
X03.00002: Novel Denoising Method for Magnetic Resonance Velocimetry Using Split-and-Overlap Singular Value Decomposition Seungmin Kang, Simon Song, Don-Gwan An, Ilhoon Jang, HOJIN HA, Dong Hyun Yang Singular value decomposition (SVD) is a powerful tool for denoising 3D data like magnetic resonance velocimetry (MRV), but its effectiveness is often limited by unclear basis selection criteria. To address this, we propose a novel method that splits the data matrix into overlapping subdomains, applies SVD, and reconstructs the data using the main basis for noise reduction. We validated this method with synthetic MRV data generated from simulated flow through a square duct contaminated with Gaussian noise, as well as real MRV data from phantom experiments using the same geometry and flow conditions. Additionally, we tested the filter's performance on in vivo thoracic aorta MRV data. Evaluations were conducted using peak velocity-to-noise ratio (PVNR), noise reduction rate, divergence reduction rate, and velocity consistency. Results showed that the split-and-overlap SVD (SOSVD) technique reduced Gaussian noise in synthetic data by 79% with a PVNR of 10-30 dB. In vitro tests showed a noise reduction of 39% and a divergence reduction of 52%. For in vivo thoracic aorta MRV data, the SOSVD technique significantly minimized noise and enhanced velocity consistency, improving overall image quality. These findings demonstrate the potential of the SOSVD technique to significantly improve clinical hemodynamic analysis. |
Tuesday, November 26, 2024 8:26AM - 8:39AM |
X03.00003: Left atrial appendage (LAA) clotting risk inferrence and flow reconstruction from 4D Contrast-CT imaging by Multi-Physics-Informed Neural Network (PINN) Bahetihazi Maidu, Alejandro Gonzalo, Clarissa Bargellini, Lorenzo Rossini, Davis Vigneault, Pablo Martinez-Legazpi, Javier Bermejo, Oscar Flores, Manuel García-Villalba, Elliot McVeigh, Andrew M Kahn, Juan Carlos del Alamo Atrial fibrillation (AFib) is the most common cardiac arrhythmia affecting one in three people worldwide. The left atrial walls move weakly and irregularly during AFib, creating regions of blood stasis and thus thrombus may form inside the LAA. Patients with AFib have higher rates of atrial thrombosis and have five times increase in ischemic stroke risk incidence than healthy individuals. Current clinical risk scores for stroke in AFib patients are not patient-specific and have moderate accuracy. Moreover, 4D Contrast-CT images used to assess left atrial hemodynamics have motion artifacts during image reconstruction, which hinders the accuracy of secondary analysis derived from contrast dynamics. |
Tuesday, November 26, 2024 8:39AM - 8:52AM |
X03.00004: Three-dimensional Super-resolution Left Ventricular Vector Flow, Pressure, & Clotting Risk Mapping by Multi-Physics-Informed Neural Network Bahetihazi Maidu, Pablo Martinez-Legazpi, Manuel Guerrero-Hurtado, Cathleen M. Nguyen, Alejandro Gonzalo, Andrew M Kahn, Javier Bermejo, Oscar Flores, Juan Carlos del Alamo Color-Doppler echocardiography and cardiac magnetic resonance imaging (MRI) are widely used to assess left ventricular (LV) flow. However, 2D echo is limited to the velocity component parallel to the ultrasound beam and 4D Flow MRI only provides velocity fields in limited planes. Vector Flow mapping (VFM) technique and its 3D variant infer missing velocity component, but they rely solely on mass conservation and are sensitive to truncated data. Moreover, VFM does not compute pressure or clotting risk; those involve secondary analyses complicating clinical translation. |
Tuesday, November 26, 2024 8:52AM - 9:05AM |
X03.00005: Comparison of image driven direct numerical simulations to 4D flow MRI in congenital heart disease Ibrahim Nasuh Yildiran, Francesco Capuano, Yue-Hin Loke, Laura Olivieri, Elias Balaras The advent of advanced medical imaging and computational techniques has significantly enhanced our ability to analyze and understand complex intracardiac flow phenomena, especially within the right ventricle (RV), which has a more intricate geometry and wall motion. The high temporal and spatial resolution in image-driven direct numerical simulations (DNS) provide more detailed insights into intracardiac flow patterns compared to four-dimensional magnetic resonance imaging (4D-MRI), which offers lower resolution imaging of blood flow. These insights can eventually provide reliable biomarkers for monitoring the evolution of postoperative morbidities and the timing of surgeries, particularly in congenital heart disease (CHD). Despite these advantages, computational models may suffer from various uncertainties, including reconstructed motion and boundary conditions. These uncertainties often limit DNS's ability to accurately capture the diastolic filling of the RV, a critical aspect of understanding CHD's fluid dynamics. To address this, we propose a computational workflow that adjusts the reconstructed motion of the RV to maintain mass conservation, thereby improving the representation of diastolic filling. We compare qualitative and quantitative results based on healthy cases against both 4D-MRI and DNS results obtained with non-adjusted RV reconstruction, demonstrating the potential for enhanced accuracy. |
Tuesday, November 26, 2024 9:05AM - 9:18AM |
X03.00006: Untangling the effects of flow transport and chamber function on left ventricular stasis Pablo Martinez-Legazpi, Javier Bermejo, Juan Carlos del Alamo Flow inside the left ventricle (LV) harbors complex swirling patterns connecting the diastolic inflow jet with the systolic outflow jet. These flow patterns wash out the chamber preventing blood stasis. LV flow patterns partition the chamber into four Lagrangian volumes with distinct transport dynamics (direct flow, retained inflow, delayed ejection, and residual volume). These regions are altered in heart failure (HF). Most notably, the direct flow volume entering and exiting the LV within the same cardiac cycle decreases, and the residual volume with residence time (RT) longer than two cycles increases. Based on this evidence, the general wisdom is that direct flow (DF) facilitates LV washout. However, this view neglects the effect of LV ejection fraction (EF), which decreases with cardiomyopathy. Applying queueing theory to LV transport, we predict how mean LV blood residence time (RT) depends on EF and DF, showing that, in fact, DF is deleterious to efficient blood transport. We validate our theory using RT measurements on ~300 volunteers and patients with acute and chronic LV dysfunction. Our results suggest that DF decrease in HF could be an evolutionary adaptation to compensate for decreased EF. |
Tuesday, November 26, 2024 9:18AM - 9:31AM |
X03.00007: Effects of Stenosis Shape and Severity on Hemodynamics of Patient-Specific Coronary Arteries: A Numerical Study Ankani Sunil Varma, Nagendra Boopathy Senguttuvan, K Arul Prakash Atherosclerosis causes plaque buildup in arterial walls, occludes the lumen region, and hinders organ functioning with inadequate supply of vitals such as nutrients and oxygen. Plaques comprising lipids are vulnerable to rupture when acted upon by perturbed hemodynamic forces. Clinical assessments of coronary arterial diseases have shown active rupture-prone sites on proximal stenotic regions and close to the throat. Stenosis severity is a salient feature of clinical interventions for treating coronary artery diseases. However, stenotic shapes with a steep proximal slope intensify hemodynamic stresses and contribute to plaque rupture, which requires thorough analysis. Computational Fluid Dynamics (CFD) simulations are performed to investigate the effect of proximal shape and sequential stenoses on reconstructed patient-specific coronary arteries. Stenosis shapes are quantified using gradients of arterial lumen along the proximal region. Further, physiological flow conditions such as baseline rest and exercise are integrated to analyse flow features, hemodynamics and pressure gradient across the stenosis. This study addresses the significance of stenosis shape, emphasizing the proximal region and severity for assessing hemodynamics in patient-specific coronary arteries. |
Tuesday, November 26, 2024 9:31AM - 9:44AM |
X03.00008: Evaluation of high-resolution image accuracy for small animal vascular flow quantitation Daibo Zhang, Stephanie E Lindsey Hemodynamics plays a vital role in early cardiac morphogenesis. Subject-specific blood flow simulations of small animal vascular networks provide key mechanistic insights into vascular growth and remodeling. Though, the accuracy of numerical simulations is critically dependent on the quality of 3D anatomical models and high-resolution image stacks from which they were obtained. Here, we analyze the morphological and hemodynamic profiles of the rapidly morphing avian pharyngeal arch arteries (PAAs) using three separate imaging modalities: 4-dimensional ultrasound (4DUS), light sheet fluorescence microscopy (LSFM), and nano-computed tomography (nanoCT). We use statistical shape modeling and geometric analysis to analyze the morphological differences between cohorts obtained from each imaging modality and perform multiscale computational fluid dynamics modeling on representative geometries. Multiscale (3D-0D) pulsatile hemodynamic simulations, in which the three-dimensional domain of interest is coupled to a zero-dimensional electric analog representation of subsequent circulation, allow for extensive pressure and flow characterization between modality-based models. Results obtained confirm LSFM images maintain the morphological intricacies of PAAs in agreement with nano-CT standards, while 4DUS is less accurate with smaller vessels. Information obtained from these models will serve as a reference for acquiring high resolution images for small animal flow quantitation. |
Tuesday, November 26, 2024 9:44AM - 9:57AM |
X03.00009: Abstract Withdrawn |
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