Şenol Pişkin

University of Texas at San Antonio | UTSA · Department of Mechanical Engineering

Background To date, multiple advanced magnetic resonance imaging (MRI) methods beyond conventional qualitative structural imaging for the diagnosis, prognosis, and treatment follow-up of glioma have demonstrated their utility for clinical studies. However, these methods often rely on complex off-scanner processing to yield the most information and...

This guide summarizes the state-of-the-art processing software solutions and the repositories/communities for the following advanced MRI methods: DSC; DCE; ASL; diffusion MRI; relaxometry; MRF; MRS; CEST; SWI; QSM; MRE; and task-based and resting-state fMRI. For each of those, after a short introduction about the method and output parameters, the r...

In complex cardiovascular surgical reconstructions, conduit materials that avoid possible large-scale structural deformations should be considered. A fundamental mode of mechanical complication is torsional buckling which occurs at the anastomosis site due to the mechanical instability, leading surgical conduit/patch surface deformation. The object...

This study aims to investigate the impact of wind to players’ perceived realism in digital games. In digital games, there is an ongoing and never ending quest for realism. As games keep getting more and more graphically demanding, game designers try to include senses in order to invoke realism. Perceived game realism is a multidimensional construct...

The selection of cardiovascular conduits during reconstructive surgical operations presents a significant challenge due to the potential complications that may arise post-operatively, depending on various parameters, including patient-to-patient variation. One particularly common mechanical complication is torsional buckling and conduit surface def...

Magnetic resonance imaging and computed tomography allow the characterization of arterial state and function with high confidence and thus play a key role in the understanding of arterial aging and its translation into the clinic. Decades of research into the development of innovative imaging sequences and image analysis techniques have led to the...

Arterial pulse waves (PWs) such as blood pressure and photoplethysmogram signals contain a wealth of information on the cardiovascular (CV) system that can be exploited to assess vascular age and identify individuals at elevated CV risk. We review the possibilities, limitations, complementarity, and differences of reduced-order, biophysical models...

Preoperative clinical MRI protocols for gliomas, brain tumors with dismal outcomes due to their infiltrative properties, still rely on conventional structural MRI, which does not deliver information on tumor genotype and is limited in the delineation of diffuse gliomas. The GliMR COST action wants to raise awareness about the state of the art of ad...

Preoperative clinical magnetic resonance imaging (MRI) protocols for gliomas, brain tumors with dismal outcomes due to their infiltrative properties, still rely on conventional structural MRI, which does not deliver information on tumor genotype and is limited in the delineation of diffuse gliomas. The GliMR COST action wants to raise awareness abo...

Preoperative clinical magnetic resonance imaging (MRI) protocols for gliomas, brain tumors with dismal outcomes due to their infiltrative properties, still rely on conventional structural MRI, which does not deliver information on tumor genotype and is limited in the delineation of diffuse gliomas. The GliMR COST action wants to raise awareness abo...

Nearly half (%40) of the patients with the symptomatic peripheral arterial disease have the aortoiliac occlusive disease (AOID). Currently, guidelines favor open surgical of AOID. No consensus is achieved on the management of multilevel occlusive disease, except to treat the inflow (i.e., aortoiliac lesion) first. There is controversial data ab...

Pulmonary hypertension (PH) is a progressive disease characterized by elevated pressure and vascular resistance in the pulmonary arteries. Nearly 250,000 hospitalizations occur annually in the US with PH as the primary or secondary condition. A definitive diagnosis of PH requires right heart catheterization (RHC) in addition to a chest computed tom...

Computational capabilities of the largest high performance computing systems have increased by more than 100 folds in the last 10 years and keep increasing substantially every year. This increase is made possible mostly by multi-core technology besides the increase in clock speed of CPUs. Nowadays, there are systems with more than 100 thousand core...

Biomechanical characterization of abdominal aortic aneurysms (AAA) has become commonplace in rupture risk assessment studies. However, its translation to the clinic has been greatly limited due to the complexity associated with its tools and their implementation. The unattainability of patient-specific tissue properties leads to the use of generali...

Background Regional mechanical characterization of pulmonary arteries can be useful in the development of computational models of pulmonary arterial mechanics.Objective We performed a biomechanical and microstructural characterization study of porcine pulmonary arteries, inclusive of the main, left, and right pulmonary arteries (MPA, LPA, and RPA,...

Purpose: This study aims to quantify the patient-specific hemodynamics of complex conduit routing configurations of coronary artery bypass grafting (CABG) operation which are specifically suitable for off-pump surgeries. Coronary perfusion efficacy and local hemodynamics of multiple left internal mammary artery (LIMA) with sequential and end-to-si...

Purpose: This study aims to quantify the patient-specific hemodynamics of complex conduit routing configurations of coronary artery bypass grafting (CABG) operation which are specifically suitable for off-pump surgeries. Coronary perfusion efficacy and local hemodynamics of multiple left internal mammary artery (LIMA) with sequential and end-to-sid...

Approximately 1 in 100 children are born with a clinically significant congenital heart defect (CHD), representing 1,300,000 children worldwide. While many of these infants failed to survive during the first half of the previous century, the past 60 years has produced dramatic advances in their palliation. Likewise advances in cardiovascular engine...

The present disclosure relates to a system for manufacturing of vascular patches in the form pre-operative surgical planning prototypes providing optimized patient specific 3-D patch geometries. The present disclosure relates more particularly to a patch generation device for manufacturing of vascular patches in the form pre-operative surgical plan...

This invention is related to an operation scenario flow, mechanical modeling and analysis system comprising web based,(i) growth (ii) scaling and (iii) quality control aimed, patient based fast prototyping functions, for newborn and fetus cardiovascular repair operations, developed in order to be used for training of doctors and patient specific po...

The present disclosure relates to a system for the manufacturing of vascular patches in the form of pre-operative surgical planning prototypes providing optimized patient-specific 3-D patch geometries. The present disclosure relates more particularly to a patch generation device for the manufacturing of vascular patches in the form of pre-operative...

Pulmonary hypertension (PH) is a progressive disease affecting approximately 10-52 cases per million, with a higher incidence in women, and with a high mortality associated with right ventricle (RV) failure. In this work, we explore the relationship between hemodynamic indices, calculated from in silico models of the pulmonary circulation, and clin...

Red blood cells (RBC) carry and deliver oxygen (O2) to peripheral tissues through different microcirculatory regions where they are exposed to various levels of shear stress (SS). O2 affinity of hemoglobin (Hb) decreases as the blood enters the microcirculation. This phenomenon determines Hb interactions with RBC membrane proteins that can further...

The objective of this study was to quantify pentagalloyl glucose (PGG) mediated biomechanical restoration of degenerated extracellular matrix (ECM). Planar biaxial tensile testing was performed for native (N), enzyme-treated (collagenase and elastase) (E), and PGG (P) treated porcine abdominal aorta specimens (n = 6 per group). An Ogden material mo...

Purpose Assessing the rupture probability of intracranial aneurysms (IAs) remains challenging. Therefore, hemodynamic simulations are increasingly applied toward supporting physicians during treatment planning. However, due to several assumptions, the clinical acceptance of these methods remains limited. Methods To provide an overview of state-of-...

Purpose Image-based computational fluid dynamics (CFD) is widely used to predict intracranial aneurysm wall shear stress (WSS), particularly with the goal of improving rupture risk assessment. Nevertheless, concern has been expressed over the variability of predicted WSS and inconsistent associations with rupture. Previous challenges, and studies f...

Purpose Advanced morphology analysis and image-based hemodynamic simulations are increasingly used to assess the rupture risk of intracranial aneurysms (IAs). However, the accuracy of those results strongly depends on the quality of the vessel wall segmentation. Methods To evaluate state-of-the-art segmentation approaches, the Multiple Aneurysms A...

Objective: This study aimed to identify the best graft-to-pulmonary artery (PA) anastomosis angle measuring pulmonary blood flow, wall shear stress (WSS), and shunt flow. Methods: A tetralogy of Fallot with pulmonary atresia computer model was used to study three different modified Blalock-Taussig shunt (mBTS) anastomosis angle configurations wi...

Surgical treatment of congenital heart disease (CHD) involves complex vascular reconstructions utilizing artificial and native surgical materials. A successful surgical reconstruction achieves an optimal hemodynamic profile through the graft in spite of the complex post-operative vessel growth pattern and the altered pressure loading. This paper pr...

Testicular artery torsion (twisting) is one such severe vascular condition that leads spermatic cord injury. In this study, we investigate the recovery response of a torsioned ram testicular artery in an isolated organ-culture flow loop with clinically relevant twisting modes (90°, 180°, 270° and 360° angles). Quantitative optical coherence tomogra...

Computational Fluid Dynamics and Finite Element Analysis are widely used tools for modeling the cardiovascular system. These models can be used in predicting surgery performance and thus planning operations beforehand. In addition, these tools could be used as surrogates for clinical measurements that can be risky and inaccurate.

Computational fluid dynamics (CFD) is a well-developed tool used in engineering and it has become the main method for design and analysis. Thanks to development of three-dimensional imaging techniques, CFD can be used to quantify cardiovascular hemodynamics in patient-specific geometries. It can be applied for predicting changes in blood flow resul...

In this study, hemodynamic performance of three novel shunt configurations that are considered for the surgical repair of tetralogy of Fallot (TOF) disease are investigated in detail. Clinical experience suggests that the shunt location, connecting angle, and its diameter can influence the post-operative physiology and the neurodevelopment of the n...

Recent clinical studies showed that the hemodynamic energy loss of the surgical conduit used in 3rd-stage repair of single-ventricle heart defects (Fontan surgery) determines the post-operative exercise capacity. Still, our understanding of the Fontan pathway energy loss is based on fully-functional conduits that are acquired from patients with opt...

Optimal hemodynamics in aorta-pulmonary shunt reconstruction is essential for improved post-operative recovery of the newborn congenital heart disease patient. However, prior to in vivo execution, the prediction of post-operative hemodynamics is extremely challenging due to the interplay of multiple confounding physiological factors. It is hypothes...

Bu buluş, sağlık sektöründe biyomühendislik alanında kalp damar ameliyat öncesi ve sonrası hastanelerde ameliyat çıktısı tahmini ve hekimlerin eğitimi için kullanılmak üzere geliştirilmiş, yeni doğan ve fetüs kalp damar tamir ameliyatları için web tabanlı (i) büyüme (ii) ölçekleme ve (iii) kalite kontrol amaçlı hasta bazlı hızlı prototipleme fonksi...

It is important to deal with the computational challenges for bio-medical fluid flow simulations and an OpenFOAM solver, icoFoam, for the large matrices coming from the simulation of blood flow in arteries on different HPC clusters. The flow problem produced various matrices as the time advances in simulation. In this study we examined the behaviou...

Presentation

Background and purpose: A variety of approaches exists where numerical methods that underlie numerous assumptions are used in order to predict rupture in intracranial aneurysms. Since many hemodynamic parameters have been derived from these computations but no persistent explanation for rupture has been found, the acceptance of CFD among physician...

Cardiopulmonary bypass (CPB) procedure is employed to repair most congenital heart defects (CHD). Cannulation is a critical component of this procedure where the location and diameter of cannula controls the hemodynamic performance. State-of-the-art computational studies of neonatal CPB employed an isolated aortic arch region by truncating the thre...

Presentation

We study a bio-medical fluid flow simulation using the incompressible, laminar OpenFOAM solver icoFoam and other direct solvers (kernel class) such as SuperLU_DIST 3.3 and SuperLU_MCDT (Many-Core Distributed) for the large penta-diagonal and hepta-diagonal matrices coming from the simulation of blood flow in arteries with a structured mesh domain....

Vascular growth and remodeling during embryonic development is associated with blood flow and pressure induced stress distribution, in which residual strains and stresses play a central role. Residual strains are typically measured by performing in vitro tests on the excised vascular tissue. In this manuscript, we investigated the possibility of es...

Cardiopulmonary bypass (CPB) procedure is employed to repair most congenital heart defects (CHD). Cannulation is a critical component of this procedure where the location and diameter of cannula controls the hemodynamic performance. State-of-the-art computational studies of neonatal CPB employed an isolated aortic arch region by truncating the thre...

In this study the biomechanical characteristics of a realistic carotid artery [3] are studied numerically using different inlet velocity profiles. Several experimental data measured [32] at the common carotid artery are used as inlet boundary conditions. Computation domain is generated using computed tomography (CT) data of a real patient. Three di...

In this study, the blood flow in human arteries is modelled. Three dimensional artery geometry is used as the model domain. The geometric model is generated using several parameters of arteries such as radius, length and curvature. After the geometry is determined, blood flow and wall movement models are constructed. For blood flow, Navier-Stokes e...

Biomechanical properties of blood flow are researched in 13 main arteries of human body. 3D blood network model consists of regions such as aorta, carotid, iliac, renal and celiac sections. A real patient data is used as the geometric domain and the Womersley velocity profile is implemented as the inlet. Investigating 13 main arteries at once as a...

In this study the biomechanical characteristics of a realistic carotid artery are studied numerically using different inlet velocity profiles. Sinusoidal and experimental data measured at the common carotid artery are used to generate the velocity inlet boundary conditions at common carotid artery. The generation is done using elliptic Womersley ve...

In this study the effects of some non-Newtonian viscosity and Newtonian viscosity models on the Wall Shear Stress and velocity distributions in carotid artery are investigated. Three distinct non-Newtonian viscosity models named Carreua, Casson and Generalised Power Method and Newtonian model are employed in the simulations. 3D Navier–Stokes equati...

A coupling between a viscoelastic structural model and a Newtonian flow model is studided. A large artery behaviour is modeled as isotropic, homogeneous, viscoelastic model while the blood flow is modeled as an incompressible, Newtonian flow model. The viscoelastic behaviour of the artery is defined using Prony series. The effect of viscoelastic be...

This paper intends to simulate 3D blood flow of carotid artery bifurcations using a suitable geometrical model with the help of various processing tools and methods. To understand flow characteristics of human blood flow, it is essential to model 3D human arterial tree with as many branches as possible. Geometric modeling of the artery network is s...

Istanbul Technical University (ITU) has long recognized the importance of Computational Science and Engineering (CSE) education, and in 2002, it designed a master's and doctoral program within its Informatics Institute. The university currently has approximately 6,000 graduate student and 11,000 undergraduates. Senior CSE members in the Informatics...

Computational Science and Engineering is a multi-disciplinary area with growing recognition in the past decade. The affordability and availability of high performance computers and communication have helped shrink the technological divide; both internally within each country and globally among industrial and developing countries. Although there is...