**3D-Printed Models Applied in Medical Research Studies**

Jorge Roberto Lopes dos Santos, Heron Werner, Bruno Alvares de Azevedo, Luiz Lanziotti, Elyzabeth Avvad Portari, Sidnei Paciornik and Haimon Diniz Lopes Alves

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/63942

#### **Abstract**

The aim of this chapter is to show experiments in cardiology and fetal medicine, two specialties of medicine, through the development of three dimensional (3D) physical models produced on additive manufacturing (AM) technologies, also known as 3D printing, from files acquired on noninvasive-imaging technologies (NITs) as 3D ultrasound (3DUS), magnetic resonance imaging (MRI), computed tomography (CT), and micro-computed tomography (micro-CT). The presentation of eight different experiments demonstrates that the combination of AM technologies and files ob‐ tained from NITs may improve our understanding of medical anatomical characteris‐ tics for medical research, simulation procedures, and educational purposes.

**Keywords:** additive manufacturing, 3D-printed models, 3D ultrasound, magnetic res‐ onance imaging, computed tomography, cardiology, fetal medicine

## **1. Introduction**

In recent years, the use of three-dimensional (3D) files generated in noninvasive-imaging technologies (NITs) combined with additive manufacturing (AM) technologies has increased exponentially. NITs are adopted to assist diagnosis in medicine allowing the physician to visualize and define relevant internal structures of the human body, as well as the conversion of the visualized information into a set of digital medical 3D data.

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Eight selected experiments developed by a multidisciplinary team of physicians, designers, and physicists are described in order to highlight the potential of the combination of AM and NITs, demonstrating that 3D representation enhances the understanding for the diagnosis and treatment in medicine.

Four NITs were adopted so as to generate 3D imaging files: 3D ultrasound (3DUS), magnetic resonance imaging (MRI), computerized tomography (CT), and micro-computed tomography (micro-CT). The routine of imaging acquisition and the AM systems are similar regarding their logical method based on the virtual "slicing" of an object, generating an amount of layers according to the thickness recommended [1].

The consecutive construction of the projected 3D computer-aided design (CAD) model can be reached throughout the superimposition of those same layers. The additive materialization process begins with the 3D CAD model, which is then "sliced" into layers that contain spatial references to guide later the deposit of selected materials, layer by layer, resulting on a physical 3D model.

The actual additive method is based upon the successive overlapping of thin layers of specific material substances, according to the appropriate technical method, and is carried out by transforming the 3D files into an STL (Standard Triangulation Language) extension, which consists basically of *X*, *Y*, and *Z* coordinates. Once the STL file is generated, the next step is the horizontal slicing of the whole 3D volumetric file using software appropriate to the specific hardware being used, and calculating the supporting structures when necessary. The building process starts with the sequential deposition of layers of material, the layer width ranging from microns to fractions of millimeters, depending on the technology chosen [1].

This process is then followed by a post-processing stage, an essential procedure in all current AM technologies, where the model has to be cleaned to remove the support material and/or residues used during the building process. In the case of some AM processes that work by using a laser beam to harden photosensitive materials, it is also necessary to position and expose the model inside an ultraviolet light camera in order to solidify the model completely.

There are presently diverse systems of AM/3D printing technologies commercially available. Although they use different material processes, they are all based on the principle of physical materialization by layer deposition. One of the most important characteristics of the additive manufacturing technology is its capability of construction parts with any geometrical intricacy, a process in which subtractive technologies as CNC equipment are sometimes limited and time consuming [1–3].
