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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_585_Библиотеки_им_академика_М_И_Перельмана.pdf
144
S. Bao et al.
inuence on the medical eld with its unique immersiveness,
interactivity, visuality, and close integration with modern
medicine. It uses specic interactive tools (input devices
such as sensor gloves and video eyepieces) to simulate the
hardware and software environment in real operation. Users
have an immersive sensation during operation. It is widely
used in aspects including surgical training, surgical rehearsals, psychology, clinical diagnosis, and telemedicine.
Computer-aided surgery (CAS) is realized by combining
computer technology, virtual reality technology, medical
imaging technology, image processing technology, and robot
technology with surgery. It is a new technology based on the
ability of computers to process and control large amounts of
data at high speed. It provides technical support for surgeons
through a virtual operation environment, making surgery
safer and more accurate. In recent years, with the development of computer X-ray, CT, MRI, and other diagnostic
imaging tools, computers use the image information for 3D
image reconstruction, providing objective, accurate, intuitive, and scientic means for surgeons to perform surgical
simulation, surgical navigation, surgical positioning, and
surgical planning. Surgical support based on this
three- dimensional position information, improves the success rate of surgery, reduces complications of the surgery,
reduces the trauma of surgery, dramatically reduces surgical
wounds, minimizes the physical pain of the patients, and
promotes the rapid development of surgical technique.
6.4.1 Application of3D Reconstruction
Technique inBiliary Surgery
The development of modern biliary surgery is closely related
to the development of science and technology and its application in medicine. Along with the cross-fusion and rapid
development of computer technology, image processing
technology, medical physics, and medicine; the means, and
concept of surgical diagnosis and treatment are changing
substantially. In recent years, computer-aided surgical systems and virtual surgery systems have been developed rapidly and applied to the medical eld. Surgeons use these
advanced technical means preoperatively, intraoperatively,
and postoperatively to ensure that surgical operation is safer,
more reliable, more accurate, and less traumatic. The complicated pipeline system inside the liver and its physiological
and pathological changes determine the difculty of hepatobiliary surgery. Previous imaging examination has provided
2D plane images. The intrahepatic duct system and its 3D
spatial relationship with the tumor could not be shown, and
liver volume could not be calculated accurately. Surgeons
could only roughly locate the intrahepatic lesion and its
related important pipeline structures by image and logical
thinking, which served as the basis for the formulation of the
surgical plan. Therefore, it had certain blindness and unreliability for complex liver surgery. In 1991, Soyer et al.
reported for the rst time the successful identication of liver
segment and subhepatic segment anatomy with 3D computed tomography arterial portography (CTAP), the display
of main portal vein, branches, and their anatomical variation,
and the clinical study of preoperative determination of segmental location of hepatic metastases. Their results showed
that the accuracy in determining the segmental location of
hepatic metastases was 94% for 3D CTAP and 78% for 2D
CTAP (1991). Soler etal. (2000) used interactive visualization and virtual cutting tools in 2000. Virtual hepatectomy
was performed on the 3D liver model in accordance with the
cutting plane developed by the user: therefore, a specic surgical protocol was designed. The operation effect was
improved. In 2000, Wolfram Lamadé et al. (2002) reconstructed the shape of VPH liver by a semiautomatic segmentation method and carried out 2D and 3D reconstruction of
four sets of intrahepatic piping systems.
The four systems can be integrated with the reconstructed
liver to simulate virtual reality liver surgery, reconstructing
the main branches of the liver, gallbladder, intrahepatic vein
system, and the internal and external bile duct system using
a VHP dataset. The model can be used to simulate virtual
endoscopic minimally invasive choledochal surgery. Other
scholars have successively carried out the 3D reconstruction
of hepatobiliary system images, including helical computed
tomographic (HCT) cholangiography combined with magnetic resonance cholangiopancreatography(MRCP) technology to show the course of intrahepatic and extrahepatic bile
ducts and their pathological changes. 3D HCT reconstruction technique has been used in the diagnosis of biliary diseases; Fang Chihua etal. (2005) reconstructed 3D images of
the liver and four canals by CT and MRI scans through
hepatic duct perfusion and cast specimens and obtained
three-dimensional models of the liver and four canals, which
can be used to simulate the operation of virtual hepatectomy.
In 2005, Li Kai etal. conducted a 3D reconstruction of the
liver, gallbladder, the intrahepatic vessels, and adjacent
structures by using a digital visual human dataset, and these
reconstructed models were displayed jointly (2005). In the
early stage, the liver of cadavers was mainly studied. By
using the technique of intrahepatic tube casting technology,
the ideal lling agent was selected. On the basis of maintaining the normal anatomical position of the liver, the location,
perfusion, embedding, freezing, milling level of the ultrathin sections were carried out. A continuous and accurate
cross-sectional dataset of the liver was obtained. The different color thresholds which lled in the hepatic conduits were
automatically recognized by the computer, and a 3D digitized visual model of the intrahepatic duct system was established. The complex spatial structure and the adjacent
relationship of the intrahepatic conduit were accurately dis-
6 Virtual Surgical Instruments andSurgical Simulation
145
played. In recent years, the virtual surgery of three-dimensional reconstruction and liver resection based on 64-slice
CT scan data of healthy liver has achieved good results.
However, due to the absence of intrahepatic bile duct data
from healthy people, 3D reconstruction cannot be conducted.
According to clinical practice, the study on reconstruction
and virtual surgery of intrahepatic and extrahepatic cholelithiasis using CT data of patients with intrahepatic and extrahepatic bile duct stones are helpful in solving the difcult
problems in biliary surgery and promoting development of
the science.
6.4.2 Simulation Surgery forIndividualized
Intrahepatic andExtrahepatic Bile Duct
Stones
Cholelithiasis is a common and frequent disease in China
and accounts for a signicant percentage of the total inpatients in the Department of General Surgery. Hepatolithiasis
is primary intrahepatic cholelithiasis. In high incidence
areas, hepatolithiasis accounts for the majority of cases.
Hepatolithias is characteristically a complicated condition,
with a high postoperative residual stone rate, recurrence rate,
and complication rate, which can induce cholangiocarcinoma. Additionally, surgical treatment of postoperative
residual hepatolithiasis presents a high degree of difculty.
In recent years, with the development of biliary surgery,
B-ultrasound, CT, MRCP, choledochoscope, and Endoscopic
Retrograde Cholangiopancreatography (ERCP) have been
widely used, and the incidence of postoperative residual
stones has been signicantly reduced. However, postoperative residual or recurrence of stones and other causes requiring reoperation is not uncommon. Preoperative understanding
of anatomical abnormalities such as the location of the stone,
the number of stones, biliary stenosis, and the formation of
cyst is an essential means to prevent residual stones and
recurrence after surgery. How to eliminate the hidden dangers of these stones before surgery? In addition to familiarization with the disease, improve the technical level, and
improve the equipment conditions, we try to apply novel
techniques to the hepatobiliary surgery in order to reduce
and eliminate these hazards.
6.4.3 Visual Simulation Surgery
ofCholecystectomy,
Choledocholithotomy, andLeft
Hemi-Hepatectomy
In the Freeform, the above model was visually simulated
according to the actual surgical procedure. In the established
virtual environment system of simulated surgery, the immer-
sion is intense and the interactivity is good. The force feedback device PHANTOM can be used to control the stereo
model at will, including zooming in, zooming out, and omnidirectional rotation. PHANTOM can be used to manipulate
the “simulating scalpel” to simulate the process of cholecystectomy, choledocholithotomy, and indwelling T tube. The
model performs a single plane cut or arbitrarily cuts, and
achieves a “force” feel when cutting, and can also feel the
magnitude of force feedback during cutting by adjusting the
strength of the cut object.
During the simulated operation: the gallbladder was
removed; the common hepatic duct was dissected; the stones
in the common hepatic duct were removed; the T tube was
indwelled; the common bile duct was sutured. The liver was
cut from the left side of the inferior vena cava to the left side
of the gallbladder notch; the dilated intrahepatic bile duct
was dissected; the exposed stones were removed; the proximal bile duct was sutured; the left branch of the hepatic vein
was severed and sutured; the right branch of the hepatic vein
was severed and sutured; the left half of the liver was removed
as a whole; the left part of the liver was transparent, and the
residual stones were visible; after the liver was clear, there
was no residual stone; the suture of the liver and the common
bile duct incision and left hepatectomy was simulated. The
simulation operation is close to the actual operation, and the
result shows that there is no residue of the stone, and the
ideal surgical effect is achieved. According to the actual
operation process, the video is entirely smooth, realistic, and
close to reality.
The liver and each conduit model are imported into the
FreeForm Modeling System. For observation, color renderings with distinct differences are given separately (Fig.6.8).
Combined with the partial transparency of the liver surface model, the distribution of the intrahepatic duct structure
and the presence or absence of abnormal variation were
observed (Fig.6.9).
Cholecystectomy: Activate the gallbladder model and
dene its force feedback intensity (Fig. 6.10a); using
PHANTOM to manipulate the “scalpel” and cut off the gallbladder duct in the neck of the gallbladder according to the
actual operation (Fig.6.10b); using PHANTOM to manipulate the scalpel. Free gallbladder bed (Fig. 6.10c); remove
the resected gallbladder (Fig.6.10d).
Choledocholithotomy: Activate the common bile duct
model and dene the strength of the force feedback
(Fig. 6.11a); use PHANTOM to manipulate the “scalpel”
and cut the common bile duct in front of the middle of the
common bile duct (Fig. 6.11b); activate the stone-cutting
forceps (Fig.6.11c); activate the stones in the common bile
duct and remove the stones (Fig.6.11d).
T-tube indwelling: Activate and adjust the position of the
T-tube model (Fig.6.12a); place the T-tube model from the
incision of the common bile duct into the longitudinal axis of
146
Fig. 6.8 After color
rendering. (a) Front view; (b)
back view
S. Bao et al.
a
b
6 Virtual Surgical Instruments andSurgical Simulation
Fig. 6.9 Liver surface model
after partial transparency. (a)
Front view; (b) back view
147
a
b
148
S. Bao et al.
a
b
Fig. 6.10 Gallbladder resection. (a) Activate gallbladder and set feedback intensity; (b) cut off the gallbladder neck; (c) mobilize the gallbladder;
(d) remove gallbladder
6 Virtual Surgical Instruments andSurgical Simulation
149
c
Fig. 6.10 (continued)
d
150
S. Bao et al.
a
b
Fig. 6.11 Choledocholithotomy. (a) Activate the common bile duct; (b) Open the common bile duct; (c) Activate the stone forceps; (d) Activate
the stone and remove it
6 Virtual Surgical Instruments andSurgical Simulation
151
c
Fig. 6.11 (continued)
d
152
S. Bao et al.
the bile duct (Fig.6.12b); use the PHANTOM manipulation
of the “suture needle” to stitch the common bile duct at the
upper and lower ends of the T-tube (Fig. 6.12c) through
rotating the liver surface and transparency of various ducts
from different directions. It is clear that all the stones have
been removed without residue, and the surgical effect is
satisfactory.
Left hemi-hepatectomy: The liver model was activated
and the position was adjusted; the hepatic parenchyma was
cut from the left side of the vena cava to the left line of the
cholecyst notch; the dilated intrahepatic bile duct was
encountered during the incision of the hepatic parenchyma
and the dilated bile duct was incised (Fig.6.13a). Intrahepatic
cholelithiasis was removed from the dilated bile duct
a
b
Fig. 6.12 T-tube indwelling. (a) Activate the T tube; (b) Indwell the T tube into the common bile duct; (c) Suture the common bile duct
6 Virtual Surgical Instruments andSurgical Simulation
Fig. 6.12 (continued)
153
c
(Fig. 6.13b); the hepatic vein encountered was severed
(Fig.6.13c); suture of the hepatic vein stump (Fig.6.13d);
continued incision of hepatic parenchyma (Fig.6.13e); severance of left portal vein branch (Fig.6.13f); suture the left
branch stump of the portal vein (Fig.6.13g); the right half
liver and its conduit were transparent and rotated without
residual stones (Fig.6.13h); residual stones in the intrahepatic bile duct can be seen after the left hepatic duct, and its
tube become transparent (Fig.6.13i); the liver section was
sutured (Fig.6.13j). The remaining right liver was re-rotated
after it became transparent and no residual stones were found
(Fig.6.13k).
6.4.4 Discussion
As an emerging research direction, simulation surgery is a
new cross-disciplinary eld combining: medicine, biomechanics, materials science, computer graphics, computer
vision, mathematical analysis, mechanical engineering,
materials, and robotics. The purpose is to use computer technology (mainly computer graphics and virtual reality) to
simulate and guide various processes involved in medical
surgery, including preoperative, intraoperative, postoperative
procedures. In order to achieve the goal, requires surgical
planning, surgical rehearsal, surgical teaching, surgical skills
training, intraoperative guided surgery, and postoperative
rehabilitation. This study is combined with clinical practice.
The clinicopathological range of intrahepatic cholelithiasis
is dened by the pathological range of intrahepatic cholelithiasis, distributed strictly along the bile duct tree, and the
many hepatic bile duct strictures. The denition of the clinicopathological range of intrahepatic cholelithiasis is that the
pathology is distributed strictly along the bile duct tree, and
there are multiple hepatic bile duct strictures. The cholestasis
caused by a stricture is the basic factor for the formation and
recurrence of the stones. It is also an important factor inuencing the effect of surgery. Removal of lesions and stones,
elimination of stenosis, unobstructed drainage, and prevention of biliary infection are key to treatment. According to
this characteristic, the dilated bile duct and its calculi were
reconstructed, and a simulated operation was carried out.
The results showed that the location of the dilation and stenosis of the bile duct, as well as the number and location of
large stones in the bile duct, were visible. The results of simulated surgery showed that there was no residual stone. This
enables the surgeons to have a full understanding of the condition of the stones and biliary tract before surgery and make
a surgical plan to deal with the situation during the operation.
Stones can be easily removed, and the stricture and dilatation
can be properly managed in order to reduce postoperative
residual stones and recurrence. The safety of the operation is
increased, while the risk and complications of the operation
are reduced.
In summary, preoperative 3D reconstruction and simulation of the relevant organs are meaningful for: the intraopera-