From 4D Medical Images (CT, MRI, and Ultrasound) to 4D Structured Mesh Models of the Left Ventricular Endocardium for Patient-Specific Simulations

Abstract

With cardiovascular disease (CVD) remaining the primary cause of death worldwide, early detection of CVDs becomes essential. The intracardiac flow is an important component of ventricular function, motion kinetics, wash-out of ventricular chambers, and ventricular energetics. Coupling between Computational Fluid Dynamics (CFD) simulations and medical images can play a fundamental role in terms of patient-specific diagnostic tools. From a technical perspective, CFD simulations with moving boundaries could easily lead to negative volumes errors and the sudden failure of the simulation. The generation of high-quality 4D meshes (3D in space + time) with 1-to-1 vertex becomes essential to perform a CFD simulation with moving boundaries. In this context, we developed a semiautomatic morphing tool able to create 4D high-quality structured meshes starting from a segmented 4D dataset. To prove the versatility and efficiency, the method was tested on three different 4D datasets (Ultrasound, MRI, and CT) by evaluating the quality and accuracy of the resulting 4D meshes. Furthermore, an estimation of some physiological quantities is accomplished for the 4D CT reconstruction. Future research will aim at extending the region of interest, further automation of the meshing algorithm, and generating structured hexahedral mesh models both for the blood and myocardial volume.

A CFD study on the interplay of torsion and vortex guidance by the mitral valve on the left ventricular wash-out making use of overset meshes (Chimera technique)

“…Despite the obvious advantages of the Chimera technique over ALE for the given study case, we did experience unexpected technical difficulties while setting up the problem. Initially, the BL meshes of the MV leaflets were separated from the BL mesh of the LV ( Figure 1C : separated LVMV): one anterior MV mesh; one posterior MV mesh; one LV mesh, whose generation is described in in ( 27 , 28 ). With this mesh configuration, however, we experienced sudden vanishing of some component zones during the CFD calculation, regardless of several attempts involving the definition of customized cut-control, the BL thickness, the mesh densities, the temporal interpolation, and smooth connecting angles.…”

“…In previous work, we built a patient-specific CFD model of the LV chamber based on the Chimera technique. Firstly, we generated a semi-automatic algorithm to generate 4D meshes of the LV with 1-to-1 vertex correspondence to replicate the patient-specific cardiac motion ( 27 ). Secondly, we investigated the impact of the LV torsion on the fluid dynamics using the Chimera technique ( 28 ).…”

Dynamic three‐dimensional virtual environment to improve learning of anatomical structures

“…In case of ultrasound, 4D ultrasound is a 3D with the time aspect—live video of the record. 4D imaging has drawn increased attention in medical imaging for improvement of diagnostic process and residents training (Markl et al, 2012; Canè et al, 2018; Gilbert et al, 2018; McAllister et al, 2018). AR and VR include the 4D concept (Zollmann et al, 2012).…”

Real-Time Smart-Digital Stethoscope System for Heart Diseases Monitoring

“…Another known technology, which uses X-ray imaging, is the computed tomography (CT) scan of the heart. Recent advancement in 3D and 4D heart model reconstruction using MRI and CT helps to visualize more than a 2D image [7,8]. The major limitation of the above technologies is the use of complex machines, which are only affordable by large hospitals, and the World Health Organization (WHO) reports [9] that the majority of cardiovascular disease are suffered by low- and middle-income countries.…”