Methods and tools for three-dimensional cardiac modeling

Alexander V. Yarovoy. Methods and tools for three-dimensional cardiac modeling. Cardiometry; Issue 31; May 2024; p. 163167; DOI: 10.18137/cardiometry.2024.31.163167; Available from:

Computer-aided design (CAD) systems are widely used not only in engineering, but also in medicine. CAD plays an important role in the medical industry by providing accuracy, efficiency, and innovative capabilities for various aspects of healthcare. Computer-aided design is employed to develop medical de- vices such as medical equipment, surgical tools, and diagnostic instrumentation. CAD is applied to develop models of the human body for surgical invention simulation and surgical planning. In medical radiology, computer-aided design systems are utilized to process and analyze images obtained with medical equipment. When creating medical devices and drugs, CAD supports in quality control, standardization of production and provides compliance with applicable regulatory standards. But one of the most relevant and promising applications of computer-aided design systems is the development of three-dimensional models of human organs and tissues.

Thanks to intensive research in the field of information technology and the development of software and hardware computing resources, advanced methods of 3D computer modeling of the heart are becoming increasingly available. Accordingly, a model-based analysis of cardiac images at clinics is becoming more accessible.

METHODS

There are a number of methods and tools for 3D cardiac modeling that are used in scientific research. Some of these methods and tools may include technologies as given below:

– Magnetic resonance imaging (MRI). MRI provides high-quality three-dimensional images of the heart. Such images are usually utilized to construct accurate models when studying the anatomy of the heart.

– Computed tomography (CT). CT scans can also provide detailed three-dimensional images of the heart that can be applied to create models of cardiac anatomy.

– 4D modeling. 4D cardiac modeling is an integration of a time-related dimension into 3D cardiac modeling. This makes it possible to take into account changes in the shape, the volume and the performance of the heart with time, which is especially important for studying the dynamics of

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cardiac activity, for example, when analyzing the functioning of the valves, heart rhythm patterns, blood flow and other parameters.

– Virtual reality (VR) and augmented reality (AR). The VR and AR technologies can be used to visualize 3D models of the heart in an interactive format. This allows researchers and medical experts to more clearly investigate the anatomy and the performance of the heart.

– Echocardiography. Echocardiography provides two-dimensional images of the heart that can be used to create three-dimensional models using special software.

– Methodology for simulating physiological processes. Three-dimensional models of the heart can be utilized to perform surgery according to simulation of physiological processes, such as heart contraction, propagation of electrical pulses, and other. This helps researchers provide a better insight into the heart performance.

– General-purpose CAD. Computer software for three-dimensional modeling is represented by such software products as Blender, 3ds Max, Maya, Rhino3D SolidWorks, Inventor, Kompas, SolidEdge, NanoCad and others. They allow developing three-dimensional models of the heart based on the obtained images.

– Specialized medical software products. Some of the well-known products are HeartModel and Sim-Vascular. In addition to creating 3D models of the heart, they help generate electrophysiological or mechanical simulations.

Three-dimensional modeling of the heart . The process of three-dimensional modeling of the heart usually begins with the stage of creating a computer reconstruction of its structure. At this stage, the three-dimensional geometry is formed. This article examines the evolution of the 3D cardiac models, with an emphasis on the methods used to create computer-generated reconstructions of the cardiac anatomy and the level of detailization of the anatomical data.

Geometric modeling. Figure 3 given herein shows that the first step in the process of creating a 3D heart model is the formation of its 3D geometry. As a rule, this geometry is represented in the form of a surface mesh. The 3D model may include one or several chambers of the heart. The large vessels of the heart [3-5], the annulus fibrosus of the atrioventricular valves [6,7], the part of the coronary tree or endocardial structures, including the papillary muscles and the trabeculae carnea in the ventricles, as well as the chest muscles and fossa ovalis for the atria [8-10] may also be imaged.

However, it is important to note that the level of de-tailization, anatomical accuracy and completeness of the 3D cardiac model required for a particular application will depend significantly on the goals and objectives of the investigation. A study [2] showed that simplified structural models (without endocardial or vascular details) are suitable for a wide range of cardiac modeling applications focused on the ventricular atrium simulation.

Figure 4 exhibits the extent to which the CAD models can accurately reflect the overall anatomy

Figure 1. The patient’s personalized two-ventricle model. (a) Intravital cardiac MRI images showing manually segmented epicardial contour. (b) 3D model of the heart superimposed on the MRI package. (c) Finite element mesh with tricubic Hermite elements showing the main direction of fiber orientation [1]

Figure 2. Highly detailed 3D two-ventricle heart model. (a) In vivo MRI. (b) 3D rendering of the model. (c) Illustration of a fragment using a tetrahedral finite element, showing the papillary muscles (green) and tendinous ligaments (blue) [2].

of the heart. They are based on measurements of the volume of the heart chambers or the wall thickness values [11,12]. They are used, as a rule, in cases where simplification of geometry can be much more important than the anatomical accuracy of modeling [13-15]. High detailization of the anatomical data can provide high quality of the histological-anatomical sections [10].

Structural remodelling coupling [Ca2+ cycling)

Electrical remodelling

Mechanical remodelling

Whole organ level (anatomical variations)

3D volumetric mesh

Electromech.

Mechanoelect, feedback

Functional remodelling

3D surface mesh

Fibre orientation

Tissue level (e.g. fibre disarray)

PMJ coupling

GEOMETRY

MESHING

3D CARDIAC COMPUTATIONAL MODEL

EP MODELS

BIOMECH. MODELS

PATHOLOGY

1                                                             1

CCS

MYOCARDIAL STRUCTURE

Figure 3. Stages of developing 3D heart geometry

Medical image-based models can contain the patient’s specific information derived from clinical imaging data as well as population characteristics collected from ex-vivo datasets (see Figure 4 herein). The initial source data may contain large intervals between slices [6,16,17]. This is common to most MRI techniques. Ex-vivo datasets (e.g. [2,18,19,20]) as well as cardiac atlases require segmentation of large numbers of the in-vivo datasets [21,22].

Manual segmentation requires specific medical knowledge. Automatic segmentation of cardiac images remains a challenging issue, especially for the in vivo data.

CONCLUSION

3D computer modeling of the heart becomes an increasingly popular area in research. With the develop-

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No direct

Medical imaging

Segmentation

Geometric

Manual

Digital image processing

Ex-viva images

Digital image processing

In-vivo images

Model-based segmentation

GEOMETRY 3D surface mesh

Figure 4. 3D cardiac geometry generation step during the development of a 3D computational cardiac model

Anatomical non-specific

Segmentation

Patient-specific

ment of information technology over the past decades, it has become possible to create customized 3D heart models that accurately reflect the personalized anatomy and unique features of the human heart.