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4 Introduction to3D Visualization ofAbdominal CT Images
113
the segmentation results, so that 3D reconstruction can be
performed after segmentation. However, it should be noted
that there are multiple segmentation results in memory after
multiple segmentation. Those unnecessary volumetric data
that have been segmented should be released in time according to the actual situation. The interface of region growing
and threshold segmentation are shown in Fig.4.14.
IntnDx [] = {0, 1, 0, -1}; // four neighbors
intnDy[]={-1,0,1,0j;
/ / Dene the queue and save coordinates X and Y
Int*pnGrowQueX= new int[nDatax*nDatay];
Int*pnGrowQueY=new int[nDatax*nDatay];//nDatax
and nDatay represent the width and height
respectively
/ / Dene the start and end of the queue. When
Start = End, there is only one point in the queue
Int Start=O, End=0;
/ / Put the seed coordinate onto the front of the
queue
pnGrowQueX[End]=seed_X;
pnGrowQueY[End]=seed_Y;
While(Start<=End)//This while-loop is used for
region growing
{
CurrX=pnGrowQueX[Start];
CurrY = pnGrowQueY[Start];
For(k=0;k<4;k++)//Go through 4 neighbors of the
current point.
{
XX=CurrX+nDx[k];
YY=CurrY+nDy[k];
If ((X) >=0&&xx<nDatax) & & (yy>=0&&yy<nDatay)
/ /Ensure that the data will not cross-border {
CurrentCord=YY*nDatax+xx:
/ / Get the pixel value of the corresponding
position of the source image and the target image
respectively
CurrentResultValue=pResultScal
ars->GetValue(CurrentCord);
CurrentSourceValue=)
pSourceScalars->GetValue(CurrentCord);
/ / The target image is identied as backcolor
in advance. When the area meets the conditions
If((CurrentResultValue==backcolor)&&
(nSeedVal-CurrentSourceValue)<=Threshold))
{
// the pointer at the end of the queue moves
one bit back and adds a point.
End++;
NTotalPixelVal+=CurrentSourceValue;
PnGrowQueX[End]=xx;
PnGrowQueY[End]=yy;
pResultScalars->SetValue(CurrentCord,foreco
lor);//Set the pixel (xx, yy) to forecolor,
indicating that the point is to be merged
nSeedVal=nTotalPixelVal/(End+1);//The gray
average of the previously divided regions
}
}
}
Start++;
} //while
Delete[]pnGrowQueX:
Delete[]pnGrowQueY:
4.3.4 The Module for3D Reconstruction
In this module, contours, MC algorithms, maximum density
projection algorithms, and ray casting methods are implemented using the functions provided by VTK. Moreover,
scaling, rotation, changing the color, adjusting the transparency, and segmenting tissue can be implemented on the
reconstructed model. The user interface is shown in Fig.4.15.
When contour and marching cube algorithms are used
for surface rendering, two functions are mainly involved:
VtkContour Filter, the function for contour, and vtkMarchingCubes, the function for marching cubes. The key for
unsegmented images is to set the value of the iso-surface.
When the value is different, the reconstructed tissue is different. The specic steps by using MC method are as follows:
• Use the vtkBMPReader class in VTK to read BMP les
and save them in the vtkStructuredPoints class.
• Use the vtkMarchingCubes class to set the value of the
contour surface and extract the contour of interest.
• Call vtkPolyDataMapper to map the data processed by
vtkMarchingCubes to geometric data.
• Dene vtkActor, specify information such as lighting,
view, and focal point of the scene, and then use the
vtkRender class to render the entities in the scene.
In the volume rendering algorithm, maximum intensity projection algorithm and ray synthesis algorithm are
used, mainly involving vtkVolumeRayCastMIPFunction
and vtkVolumeRayCastCompositeFunction. The effects
achieved by these two algorithms are quite different. For the
ray synthesis algorithm, how to set the mapping function is
the key which determines the effect, that is, how to set the
mapping relationship between grayscale and transparency
and color values. VTK mainly involves three classes: vtkVolumeRayCastCompositeFunction, vkt piecewise Function,
and vtkColorTransferFunction. Among them, vtkVolumeRayCastCompositeFunction denes a ray synthesis function,
114
S. Bao et al.
Fig. 4.14 Segmentation
interface. (a) Interface of
regional growth algorithm;
(b) interface of threshold
segmentation algorithm
a
b
and vtkPiecewiseFunction denes the mapping relationship
between CT values and transparency values in a piecewise
manner, while vtkColorTransferFunction is a transformation
function that denes the CT value and the color value.
The specic steps for using ray casting are as follows:
• Read the sequence BMP les with the vtkBMPReader
class in VTK, and store their information in the vtkStructuredPoints class.
• Set its CT value to transparency and color value mapping,
the vtkPiecewiseFunction class and vtkColorTransferFunction class are mainly used.
• Use the vtkVolumeRayCastMapper class to achieve data
mapping.
• Dene the vtkVolume Actor, specify information such as
scene lighting, view, and focus, and then use the vtkRender class to render the entities in the scene.
4.3.5 The Module for3D Model Exporting
MI-3DVS integrates image segmentation with 3D reconstruction to form a simple 3D visualization system. The
system meets the basic requirements of data visualization of
the abdomen, such as 3D visualization of liver, blood vessel,
4 Introduction to3D Visualization ofAbdominal CT Images
115
Fig. 4.15 Reconstruction interface
and spleen. Three-dimensional reconstructed models can be
saved in this module, so that these models can be brought up
directly afterward without the need for re-segmentation and
reconstruction. The saved formats include STL, PLY, and
OBJ.At the same time, the module also realizes the function
of saving any image data of the volume data. However, for
some complex pipelines, such as the gastrointestinal tract,
the system is still unable to separate them well.
References
Cirne MVM, Pedrini H.Marching cubes technique for volumetric visu-
alization accelerated with graphics processing units. J Braz Comput
Soc. 2013;19:223–33.
Kang SH, Won Y, Lee K, Youn SI, Min S-H, Park YS, Ahn S-H, Kim
H-H.Three-dimensional (3D) visualization provides better outcome
than two-dimensional (2D) visualization in single-port laparoscopic
distal gastrectomy: a propensity-matched analysis. Langenbeck’s
archives of surgery; 2020.
Nicolas G, Fabio C, Daniel A, Reto S, Guoyan Z, Philipp F.Evaluation
of CT-MR image registration methodologies for 3D preoperative
planning of forearm surgeries. J Orthop Res. 2020;38(9):1920–30.
Pattana S, Sakuntam S, Kentaro O.Selective-area growth and charac-
terization of cubic GaN grown by metalorganic vapor phase epitaxy.
Thin Solid Films. 2020;709:138205.
Santos J, Oliveira MR, Arrais R, Veiga G.Autonomous scene explora-
tion for robotics: a conditional random view-sampling and evaluation using a voxel-sorting mechanism for efcient ray casting.
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Wang J, Huang Z, Yang X, Jia W, Zhou T.Three-dimensional recon-
struction of jaw and dentition CBCT images based on improved
marching cubes algorithm. Procedia CIRP. 2020;89:214–21.
Application of3D Printing Technology
inHepato-Biliary-Pancreatic Surgery
ChihuaFang andZhaoshanFang
5
5.1 Introduction
Although 3D printing was already proposed in the nineteenth
century to produce topographic maps layer by layer, the rst
real attempts to generate objects that way were made in the
1980s. Swainson of Denmark proposed a process to directly
fabricate a product by selective 3D polymerization of a
photosensitive polymer (Swainson 1977). In 1979, Nakagawa
of Tokyo University reported the use of lamination techniques
to produce actual tools (Nakagawa et al. 1979). In 1981,
Hideo Kodama of the Nagoya Municipal Industrial Research
Institute (Nagoya, Japan) rst proposed the protocol of a
functional photopolymer rapid prototyping system (Kodama
1981). The United States and Japan pioneered the practical
development of real 3D printing technology. In 1986, Charles
Hull founded 3D Systems, Inc., and this company developed
the stereolithography (STL) le format; in 1988, 3D Systems
introduced the world’s rst commercial 3D printing system,
the SLA-250 (Ventola 2014). It was in the year 1988 that
Scott Crump invented and patented a new 3D printing
method called Fused Deposition Modeling (FDM); Crump
went on to found Stratasys, Inc., and this company developed
the rst FDM 3D printer in 1992 (Bagaria etal. 2018).
Traditional manufacturing mainly uses the principles of
mechanics, temperature, and pressure. Generally, the
technical process of production can be divided into cold
scrap removing and thermal deformation processes. Common
operations including shearing, grinding, corrosion, and
melting are used to remove the redundant parts and to obtain
the shape of components. These individual components are
then assembled and welded into nal products. Additive
manufacturing represented by 3D printing technology and
C. Fang (*)
Zhujiang Hospital, Southern Medical University,
Guangzhou, China
Z. Fang
The Fifth Afliated Hospital of Guangxi Medical University,
Nanning, China
rapid prototyping is an “integrated” high-tech developed in
the 1980s, which combines computer, CNC technology,
laser technology, CAD/CAM, and materials science in one.
Compared with traditional manufacturing methods which
involve removing parts of a block of material to form the
desired shape, 3D printing technology produces far less
material waste since it only uses the material necessary to
create a part. The manufacturing cycle by conventional
methods usually takes a long time, and the shape of sloped
surfaces and deep slots are difcult to produce; while additive manufacturing, also known as 3D printing makes up for
the shortcomings of the above traditional manufacturing processes, showing its tremendous advantages of “green
technology.”
5.1.1 Principles andConcepts of3D Printing
3D printing, also known as rapid prototyping, refers to
advanced technology for manufacturing 3D objects by stacking layers of dened sheet materials such as metal and plastic. 3D printing technology is mainly used to “manufacture”
products by means of layering processing and superposition
through computer control, and its core is the combination of
digital, intelligent manufacturing, and materials science. 3D
printing is fundamentally different from traditional manufacturing. It has opened a new era of manufacturing and has
been hailed as the foundation of the “Third Industrial
Revolution” by The Economist.
5.1.1.1 Principles andWorkow of3D Printing
Principles of3D Printing
3D printing involves a rapid prototyping device generating
3D objects by successively “printing” thin layers through
stacking sheets of paper and photocuring technology. The
mechanism of 3D printing resembles that of the ink-jet
printer. A 3D model is rst produced using 3D design software, and then the drawings are bundled up into a G-code
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
C. Fang, W. Y. Lau (eds.), Biliary Tract Surgery, https://doi.org/10.1007/978-981-33-6769-2_5
117
118
C. Fang and Z. Fang
le, the native language of a 3D printer. The G-code is then
sent to the 3D printer where it is generated into a 3D printout.
In 3D printing, the printer generates the object by adding
layer upon layer of material until the shape of the object is
formed. The object can be produced using various adhesive
printing materials, including metal or plastics.
3D Printing Workow
There are four typical phases to obtain a physical object by
3D printing technology: modeling, slicing, printing, and
post-processing.
Modeling There are two main methods of 3D modeling
for 3D printing. One is to directly create 3D digital models
using software such as AutoCAD, 3Dmax, and Blender;
the other is to rst acquire 3D data of the object using a 3D
scanner such as Polhemus, 3D CaMega, and Z Corp., and
then those data are processed to generate a digital 3D
model.
Slicing
In 3D printing, the virtual 3D model needs to be
sliced into corresponding 2D graphics and then the 2D
graphic information is printed. The thickness of the slice is
determined by the properties of printing materials and specications of the printer.
Printing There are a continually expanding group of processes used in 3D printing. Essentially building up layers
and fusing, either with an adhesive, or by applying energy
to fuse the substrate. The substrate may be in a vat if liquid,
in a bed of powder, or extruded from a ‘print head’. Applied
energy is in the form of heat, where the substrate is either
extruded in molten form by the printer and fused in situ, or
by the application of energy such as infra-red, UV light,
Laser or Electron beam. Solid objects can also be produced
by materials such as alloy powders applied layer by layer
and sintered in situ.
Fused Deposition Modeling
By using this technology, a continuous lament of thermoplastics such as acrylonitrile–butadiene–styrene nylon and
wax, is heated in a liqueer into a semiuid state. Under the
control of a computer, a wide variety of these semiuid
materials are extruded by a 3D printer extruder according to
the cross-sectional prole information. After the object is
solidied, a single layer of the desired model is formed; by
deposing material layer by layer, the nal product is achieved.
A representative company using such technology is Stratasys.
Stereolithography
SLA uses photopolymer resin as the printing material. A
computer-guided ultraviolet (UV) laser is used to scan the
photopolymer resin. The print is gradually lifted and new
layers are printed (xed by the UV laser) from below. Since
the photopolymer resin is sensitive to UV light, the resin
becomes photochemically solidied, stacking layer upon
layer of material to form the nal object. Generally, the
material used is a liquid photopolymer resin, and the
representative company is 3D Systems.
Selected Laser Sintering
Under laser irradiation, the powdered materials become sintered. According to the information of interface prole,
selective sintering is carried out under the control of computer
to accumulate and shape the parts. The typical working
materials for this process include metal powder, ceramic
powder, and thermoplastics. The representative companies
include 3D Systems and EOS.
Direct Metal Laser Sintering
DMLS uses a high-wattage laser to melt and fuse a layer of
alloys and metallic powders together, and the process should
be repeated layer after layer until the part is completed. This
technique is based on alloy metals. Representative enterprises
include EOS and MT.
Post-processing After printing, residues of printing materi-
als can cling or remain in the model, and the object normally
comes out of the printer with burrs uneven surface. In view
of these issues, excess powders can be removed manually,
and the burrs and rough surface can be polished; afterward,
the 3D physical model should be glued to enhance the hardness; nally, coloring should be performed before a nal
product is achieved.
5.1.1.2 Types of3D Printing Technologies
Currently, 3D printing mainly includes fused deposition
modeling (FDM), stereolithography (SLA), selected laser
sintering (SLS), direct metal laser sintering (DMLS),
laminated object manufacturing (LOM), electron beam melting (EBM), and three-dimensional printing (3DP).
Laminated Object Manufacturing
In LOM, the working material consists of a roll of thin “laminate.” A laser cuts the outline from a slice of the original
image. A heated roller presses the laminate cutting onto the
previous layer, the laminate roll moves forward and the next
layer is cut, heat rolled, and the process continues. Materials
used include plastic, paper, or aluminum foil. Representative
companies include Helisys and Kinergy.
Electron Beam Melting
The EBM process manufactures parts by melting metal powder layer by layer with an electron beam under a vacuum.
Generally, the working material is a titanium alloy, and the
representative company is Arcam AB.
5 Application of3D Printing Technology inHepato-Biliary-Pancreatic Surgery
119
Three-Dimensional Printing
3DP is a printing process using a droplet ejection method.
Through an ink-jet printing head, a liquid binder is sprayed
into a layer of powder, and then the binder is solidied,
forming a solid layer. This layer-by-layer process repeats
until the desired model is formed. Generally speaking,
colored plaster is used as the representative material, and the
representative company is 3D Systems.
5.1.1.3 Technical Requirements ofMedical 3D
Printing
Only through high-quality original CT images and highdelity 3D reconstructed model can we obtain a highprecision and high-delity printed physical model. Therefore,
there are three technical requirements regarding the printing
of a 3D physical model for hepatobiliary and pancreatic
diseases.
Acquisition ofHigh-Quality Thin-Slice CT Images
inDICOM Format
The quality of CT data can be affected by (a) the parameters
of original data acquisition, (b) the quality, dose, and
injection speed of contrast agent, and (c) module function of
different software. Therefore, clinicians, radiologists, and
technologists should work together to optimize parameters,
so as to collect high-quality thin-slice CT images (Thin
slices, as used herein, refers to medical images with a
thickness of 0.625–1.5mm), so as to obtain CT data with
better contrast (good signal-to-noise ratio), which is very
important in 3D modeling. The quality of CT data directly
affects the accuracy of the subsequent 3D visualization
model of liver, bile, and pancreas.
Construction ofHigh-Fidelity 3D Models
CT value is the basis of images. The 3D modeling process
may inevitably lose details in the original raw data, which
leads to distortion of the 3D reconstruction accordingly.
Using 3D visualization technology, 3D reconstruction is
performed by preprocessing, image segmentation, surface
rendering, and volume rendering of the original DICOM
data. This secondary processing of the original 2D images
may lead to some degree of image distortion. In order to
reduce image distortion, it is necessary for a Hepato-biliarypancreatic surgeon who has mastered the 3D reconstruction
software and who is competent and experienced in lm
reading to analyze the image and reconstruct the 3D model.
Only in this way can the 3D printed model be faithful to the
original data of CT.
High-Performance 3D Reconstruction Software
The performance of the 3D reconstruction software affects
the delity of reconstruction. 3D visualization technology
involves multiple steps including image data preprocessing,
segmentation, registration, 3D reconstruction, and
visualization display; and it is related to different algorithms
or methods of computer image and graphics processing. The
processing or calculation of the above different steps may
result in the loss of original data, thereby affecting the
precision of the reconstruction. Therefore, the requirements
of high-delity for 3D printed objects can be satised by
optimizing the algorithms of various reconstruction methods
and improving the delity of 3D reconstruction.
5.1.1.4 Benets andDrawbacks of3D Printing
inMedical Applications
Advantages of3D Printing
High printing accuracy, constant prototyping and enhanced
productivity, customization and personalization, and cost
reduction.
Disadvantages of3D Printing
Challenges of 3D printing include limited size of objects,
limited raw materials, and restriction on printing highprecision instruments.
There are potentially deciencies in medical 3D printing,
especially in 3D printing of hepatobiliary and pancreatic
models:
• CT image quality affects the quality of the printed model.
3D printed models can be produced by CT-based
volumetric medical images. Loss of details in DICOM
images may inevitably lead to distortion in 3D modeling,
which in turn directly results in information loss in the
preparation stage of printing. The above three situations
may cause different degrees of distortion in the 3D printed
object.
• The 3D printer and printing materials affect the quality of
the model. The performance of the printer affects the
quality of the printed model; the type, texture, and
properties of printing materials also affect the performance,
transparency, tissue elasticity, and stability of 3D printed
objects.
• 3D printing is expensive and time-consuming. Igami etal.
(2014) believed that it takes about 18h and approximately
50,000 ¥ to print a 3D liver at a scale of 70%; the printing
time and cost could increase twofold; moreover, 2–3days
are required for post-processing. Zein etal. (2013) pointed
Printing a liver model can take up to 2days plus one more
for post-processing (Kuroda etal. 2017), and the cost of
printing material ranges between $500 and $800. The cost
in time and money are factors that restrict the conventional
application of 3D printing in hepatobiliary and pancreatic
surgery. 3D printing is only suitable for some screened
patients, not for emergency patients.
120
C. Fang and Z. Fang
5.1.1.5 Applications of3D Printing
In the current scenario, 3D printing has facilitated advances
in industrial manufacturing, custom art, aerospace, and
biomedical industries. “Urbee,” the world’s rst 3D printed
car was created by Ecologic and Stratasys in November
2010; SULSA, the world’s rst 3D printed aircraft was
developed by engineers at the University of Southampton in
August 2011; in November 2012, the world’s rst 3D printed
articial human liver tissues were created by Scottish
scientists; in October 2013, a 3D printed artwork nicknamed
“the God of ONO” was successfully auctioned; in November
2013, a Texas company by the name of Solid Concepts has
manufactured the world’s rst 3D printed metal gun; In
China, a large-scale integral titanium alloy key main loadbearing part has been successfully produced by the Beijing
University of Aeronautics and Shenyang Aircraft Design
Institute, and this project won the rst National Award for
Technological Invention in 2012, which made China the rst
country in the world to successfully install such components
into engineering applications. These high-tech products have
promoted the development of 3D printing technology into a
new era.
5.1.2 Medical Applications for3D Printing
The rapid development of 3D printing technology has promoted its application in the medical eld. Correspondingly,
advances in medical 3D printing technology have made
tremendous contributions to clinical repair and treatment,
medical model manufacturing, tissue organ regeneration,
and drug development and testing.
5.1.2.1 Clinical Repair andTreatment
Medical implants produced by 3D printers can better integrate into the human body and improve therapeutic efcacy.
In March 2014, three bone tumor patients were treated in
Xijing Hospital, The Fourth Military Medical University,
Xian, China. Their bone defects, in different locations were
repaired by implantation of customized 3D printed titanium
alloy prosthesis. This was the rst clinical application of 3D
printed titanium scapula prosthesis and clavicle prosthesis in
the world, and the rst application of pelvic prosthesis in
Asia (Fan et al. 2015). In August of the same year, The
Department of Orthopedics of the Peking University Third
Hospital completed the rst worldwide treatment for atlantoaxial malignant tumor by 3D printing technology, which has
opened up a new way to reconstruct cervical vertebral structure after tumor resection.
5.1.2.2 Medical Model Manufacturing
Medical models have been extensively used in the teaching
of basic medicine and clinical trials. However, the traditional
method of producing medical models is complicated and
time-consuming and they are easily damaged because most
of their raw materials are plaster. In recent years, the use of
corpses for medical anatomy teaching has become more and
more ethically debated and socially controversial. With the
progress of 3D printing technology, printed physical models
can be used for anatomical teaching. Medical experimental
models not only help avoid the above problems, but also
realize the personalized manufacturing of special models
according to specic needs. After obtaining DICOM data
based on MSCT scanning for different parts of the human
body, the data can be reconstructed into le formats such as
STL, VRML, and PLY by 3D reconstruction software; any
human organs can be replicated by a 3D printer. By using 3D
printing technology, any anatomical parts, including upper
limbs, hands, coronary arteries, and trachea can be printed
into physical models, and these models can provide more
information than 2D images.
5.1.2.3 Tissue/Organ Regeneration
How to build replacement tissues and organs remains a challenging problem in clinical medicine? Many end-stage
(tumor) patients in need of organ replacement have lost their
lives because of the persistent organ shortage. As science and
technology continue to evolve, 3D printing of human organs
is becoming possible and will moderate the disparity between
organ supply and organ demand. 3D printing of some viable
organ components has already become possible. In 2013, a
US military funded research made a major breakthrough on
3D printing for skin and kidney. More recently, German
researchers have produced exible articial blood vessels
using 3D printing technology; these vessels can fuse with
human tissue, not only to avoid rejection, but also to grow
muscle-like tissue. These successful cases suggest that it is
becoming possible to address the current and future articial
organ shortages by 3D printing.
5.1.2.4 Development andTesting ofDrugs
At present, most of the drug testing is carried out on laboratory animals. It is difcult to get accurate feedback of pharmacological effects on humans. The human liver, kidney, and
specic cell tissues printed by 3D technology for the testing
of new drugs can not only truly simulate the human body’s
response to drugs, but also obtain accurate test results, which
can reduce the initial development cost. In 2013, Organovo,
Inc. printed a miniature liver with a depth of 0.5mm and a
width of 4mm using a 3D printer. Twenty layers of liver cells
and vascular wall cells were printed by a bioprinter in a layer
by layer manner. The 3D bioprinted mini livers can perform
all of the many vital life functions of a real human liver,
including metabolism of proteins and cholesterol, enzyme
activation, and excretion of drugs. The undeniable benets of
3D bioprinted liver models are gradually being highlighted
5 Application of3D Printing Technology inHepato-Biliary-Pancreatic Surgery
121
in new drug development and drug toxicology testing.
Although several issues remain to be addressed, it is anticipated that 3D printing will continue to evolve and play an
essential role in liver tissue engineering.
5.2 3D Printing forHepato-BiliaryPancreatic Diseases
The basic steps of 3D printing for surgical diseases of the
liver, pancreas, and biliary tract are as follows: upper
abdominal thin-layer DICOM data acquisition, 3D digital
preparation, 3D physical model printing, and 3D printing
post processing (Fig.5.1).
5.2.1 Acquisition ofCT Data
An enhanced thin-layer scanning of the liver, bile, pancreas,
spleen, and abdominal vessels in the upper abdomen was performed by Multidetector Computed Tomography (MDCT) or
an enhanced thin-layer of MRI. Multiphase images (plain
scan phase, arterial phase, portal venous phase, and delayed
phase) were obtained with an image slice thickness of 0.625–
1.5mm. Data was archived in the DICOM format.
5.2.2 Digital Preparation
Thin-layer CT data were rst processed by a post-processing
workstation, and then imported into a 3D visualization
software system (such as MI-3DVS, China; Mevis, Germany;
or MIMICS, Materialise, Belgium) for program segmentation
and reconstruction. Note: careful and accurate reading and
analysis of CT images before 3D reconstruction are important
to ensure the accuracy of 3D modelling. The DICOM data
were analyzed, fused, calculated, segmented, and rendered
by a 3D software system. The shape and spatial distribution
of the liver, biliary tract, blood vessels, and lesion were
described and interpreted; 3D image models of intrahepatic
vessels and lesion were obtained and exported to a mesh- type
le (stereolithography (STL) le), or in other formats, such
as VRML and PLY.These les were prepared for 3D printing.
Files in STL format were acquired and further processed by
Materialise Magics software in order to (a) assess the
accuracy of intersecting vessels and bile ducts arising from
subtle time or position artifacts between CT imaging phases,
thereby generating nonoverlapping geometric gures, (b)
perform hollowed vascular and bile duct structures, and (c)
divide liver mesh structure (stereolithography (STL) le)
into graft and remnant parts according to the proposed
surgical resection plane.
3D data DICOM
3D physical model
Fig. 5.1 Flow chart of 3D printed physical model
3D reconstruction
3D printing post-processing
3D printing
122
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C. Fang and Z. Fang
5.2.3 3D Printing forHepato-BiliaryPancreatic Diseases
The STL les produced through digital preparation were
imported into a 3D printer (such as Connex 350 3D printer,
Stratasys; or 3D Printer, AGILISTA-3100, Keyence Co.;
Spectrum ZTM 510 3D Printer, Z Corporation) for printing
3D physical models of intrahepatic and extrahepatic biliary
tract, blood vessels, and lesions (Figs.5.2, 5.3, 5.4, and 5.5).
Liver parenchyma can be made of transparent materials such
as Tango or Vero, or jelly wax; hepatic vein structure can be
Tangoblack or Veroblue; other vessels can be mixed with
transparent materials such as Tango or Vero; ZP 150 powder
can also be used for printing.
5.2.4 Post-Processing of3D Printing
Post-processing of 3D printed physical models for surgical
diseases of the liver, pancreas, and biliary tract mainly
involves reprocessing of the support materials and vessels.
For example, after 3D physical models are printed by the
Connex 350, removing support or excess material from the
3D print is a necessary step; the vessels are injected with
color dye by a water gun, and the liver surface is coated to
obtain visualized intrahepatic bile duct and vascular structure.
After 3D physical models of intrahepatic bile ducts, blood
vessels, and lesions are printed by the Spectrum ZTM 510,
excess powder of the 3D print should be manually removed;
and then the surface of the model should be osmotically
cured using a curing agent Z-Bond90 (3D Systems, USA).
The physical model of the hepatic parenchyma shell and the
model of the hepatic ducts are assembled to form the casting
mold. The liquid transparent wax is injected into the mold.
After solidication, the outer casting should be removed to
obtain the transparent 3D physical model.
Fig. 5.3 Front view of 3D printed model of hilar cholangiocarcinoma.
Note: Green for intrahepatic dilated bile duct system, orange for hilar
tumor, dark blue for portal vein system, and red for celiac artery system
Fig. 5.2 3D printed model of intrahepatic vessels and tumors of central HCC. (a) Front view; (b) back view. Note: Dark blue for hepatic vein
system, pink for portal vein system, and red for celiac artery system
ab
5 Application of3D Printing Technology inHepato-Biliary-Pancreatic Surgery
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Fig. 5.4 Front view of 3D printed model of hepatolithiasis. (a) 3D
printed model of left intrahepatic calculi; (b) 3D printed models of left
and right hepatic calculi. Note: Red for the celiac artery system, dark
blue for the hepatic vein system, green for the dilated bile duct, light
blue for the portal venous system, and white for hepatolithiasis
ab
Fig. 5.5 3D printed physical model of ampullary tumor. (a) Front view; (b) back view. Note: Dark brown for the ampullary tumor, dark blue for
the portal vein system, green for the dilated bile duct system, and red for the celiac artery system
5.3 Application of3D Printing
forComplicated Hepato-BiliaryPancreatic Surgery
With the development of computer technology, 3D visualization technology for 3D modelling has become an important
auxiliary tool for planning surgically complicated hepatobiliary and pancreatic surgery. This technology has more
advantages than conventional CT and MRI 2D imaging.
However, 3D images reconstructed based on the patient’s
MDCT data are usually displayed on a 2D computer monitor, so the true depth perception response is limited, and different physicians have different perceptions of the spatial
anatomical relationship between blood vessels and liver
tumors. 3D physical printing of images based on 3D visualization has broken through this bottleneck. By observing 3D