3D modeling of the nerves of the left upper limb - Introduction

1 Introduction and objectives

1.1 Objectives

1.2 State of play

1.3 History of computer modeling

2 Materials and Methods

2.1 Materials and methods of the Korean Visible Human (KVH)

2.1.1 Body selection

2.2 MRI and CT

2.2.1 Preparation of the cadaver

2.2.2 Photographs of the anatomical sections

2.2.3 Segmentation of cuts

2.3 Winsurf software

2.3.1 Presentation of the Winsurf software

2.3.2 Software functions

2.3.3 The 2D interface

2.3.4 The 3D interface

2.3.5 Practical use of Winsurf

2.4 Characteristics and data used for modeling

3 Results

3.1 Modeling the median nerve

3.2 Modeling the radial nerve

3.3 Modeling the ulnar nerve

3.4 Modeling the musculocutaneous nerve

3.5 Modeling the medial cutaneous nerve of the arm

3.6 Modeling of the medial cutaneous nerve of the forearm

4 Discussion

4.1 First step: theoretical knowledge

4.2 Second step: identification of the nerves of the left upper limb

4.3 Third step: contouring

5 Conclusion

6 Bibliographic references

Since the 90's, many nationalities have embarked on projects of three-dimensional reconstruction of the human body from anatomical sections with the aim of creating an atlas of human anatomy in three dimensions. In the wake of the Chinese, American and Korean precursors, a large number of students from René Descartes University have participated in the major project of vector and three-dimensional modeling and reconstruction of the human body based on anatomical sections of the Korean Visible Human (KVH). Each student chooses an anatomical region and has to model it as precisely as possible.

The nerves of the left upper limb not having been realized, I took the initiative of this project to bring a complement to the anatomical model undertaken by the students of the DUACN.

Therefore, the purpose of this dissertation is to present a 3D reconstruction of the nerves of the left upper limb in humans. It was performed over the period from October 2017 to May 2018.

The various objectives of this dissertation are to:

• Perform 3D modeling of the left upper extremity nerves and brachial plexus roots from the anatomical sections of the KVH ;
• To create a 3D atlas of the human body for educational purposes by providing an additional, virtual and dynamic learning method of real anatomy [1] ;
• Share this 3D atlas with a wider audience. 


The illustrations are the basis for learning medicine and especially anatomy.

Therefore, the purpose of this study is to vectorially and three-dimensionally reconstruct the nerves of the left upper limb of the Korean Visible Human (KVH) for secondary application and use in the academic and medical-surgical field.

The American Visible Human Project (VHP) was the first major project to present a database containing a series of sections from a whole human body. It was carried out on male (1994) and female (1995) cadavers [2]. The VHP database is made up of images of anatomical sections, CT and MRI. After 3D reconstruction, this database allowed various clinical applications such as dissections, endoscopies and virtual surgeries. However, the VHP project was incomplete and had some limitations [3] [4]. First, the two cadavers used were those of elderly, obese individuals with many comorbidities. Second, the MRI and CT images did not cover the entire body. Third, the anatomic images from the VHP did not include anatomic structures less than 0.2 mm thick because the sections were made with a minimum interval of 0.33 millimeters. Fourth, the anatomical colors from the VHP did not match those of a living human body, due to the use of formaldehyde as a fixative before the sections were made. Finally, the authors of the VHP did not publish a database containing segmented sections.

The Chinese Visible Human (CVH) database was created in 2002 using a male body and in 2003 using a female body. CVH is a project that also has some limitations. Like its predecessor, the colors are not very transposable to the anatomical reality because of the use of a red gelatin solution. Sections are spaced at 1.0 mm or 1.5 mm apart, except in the head and neck. Finally, the CVH has not published any segmented sections.

Following the VHP and the CVH, the Koreans decided to create their own anatomical database in 2002: the Korean Visible Human (KVH). Their goal was to improve and complete the existing database.

A male cadaver was selected, and the scientists did not use any fixing solution, in order to preserve the natural colors of the body. It was a 33 year old man, 1m64 tall and weighing 55kg, who died of pneumonia, lymphoma and splenomegaly.

The entire cadaver was digitized by MRI and scanned every 1.0 mm and then completely sectioned into 0.2-mm slices. The images were complete, and the database without any missing sections. Organ segmentations were performed and shared by the Korean team.

Several works have already been done using anatomical sections from the KVH:

• An explanation of the techniques used and the various applications [5] ;
• 3D models of the male urogenital tract (including one by Professor Uhl and Professor Delmas, in charge of the virtual anatomy unit at Paris Descartes, in association with JS Park and MS Chung, head of the anatomy department at the Korean Medical University) [6][7] ;
• A 3D model of the gastrointestinal tract [8];
• A 3D modeling of the liver and its neighboring structures [9] ;
• A 3D modeling of the lumbosacral structures [10] ;
• A 3D modeling of the ear structures [11] ;
• 3D models of the brain, skull and face [12][13] ;
• A fifth atlas with the different anatomical planes of the head [4][14] ;

As well as a KVH data navigation software allowing free access to the 3D whole body models [15] as well as a PDF file using Adobe Reader (allowing 3D view) freely downloadable from their website [16]. This was set up to be used as a self-learning anatomy tool (for adults and even children) and to be a robust source for virtual simulations for students and clinicians.

Computer modeling of anatomical and histological structures soon proved to be very useful for visualizing their shape in three dimensions. Computerized models allow the visualization of complex shapes derived from 2-dimensional tracings. Numerical simulation and prediction allow to test functional or morphogenetic hypotheses.

In the 1970s, the generation of 3D models consisted in tracing the contours of histological structures on opaque paper. These contours were then superimposed to generate a 3D structure. In the same way, wax and plaster models were made, notably by Gaunt in 1978.

Computer applications for 3D modeling appeared in the 1970s. The edges of the structures were digitized and the digital structures were expressed as a superposition of lines. Although this was a good first step, the structures lacked surface information. In the 1980s, a considerable effort was made to develop algorithms capable of modeling these surfaces. Two approaches were chosen : surface modeling and solid modeling.

Surface modeling" reconstructs the object as a shell. The structures are digitized manually or automatically and the edges are represented as contours. The space is defined by configuring a window and its environment works with a scale. The scale consists of a tissue magnification factor and thickness. Geometric configuration algorithms are used to place each contour in superposition with the next contour on each slice to create a kind of digital grid.

The "surfdriver" software was designed using this method (Lozanoff, et al., 1988).

Solid modeling represents the object as a discrete volume. A space is created in the same way as in surface modeling, but the addition of data consists in adding voxels (unit of a volume model). The voxels are stacked on top of each other and the whole is managed by computer.

An alternative approach that merged these two concepts was described by J.D Boissonant (1988). It has been significantly improved since (Lozanoff and Deptuch, 1991). Using this approach, volumes are constructed around the contours using the Delunay and Voronoi diagram. The intersection planes between the contours and the volumes are identified and the surfaces are cut from these intersections.

An easy-to-use desktop application was designed (Surfdriver) to allow rapid and reliable modeling of sectioned biological material. An ancestor of Surfdriver based on these methods was used for morphological analysis of craniofacial growth (Lozanoff and Diewert, 1989; Lozanoff et al., 1993).

Marie Messager
Osteopath in Versailles
78 - Yvelines