**5. Dong's digital liver classification**

**4. 3D simulation software and Hisense Computer Assisted Surgery** 

liver simulation in the operating room using a gesture-controlled display (**Figure 4**).

were acquired at 10 and 40 s after the arterial imaging [23].

CT imaging can be performed using a 64-row-MDCT Scanner (Sensation64; Siemens, Erlangen, Germany) with the following parameters: kVp 120, mAs 100, slice collimation 0.625 mm, feed/rotation 12 mm, and rotation time 0.5 s. Patients received 2.0 ml/kg of an iodinated contrast agent (Ultravist; Bayer HealthCare LLC, Germany) to delineate the hepatic vasculature, which was administered intravenously using an automated injector system (CT 9000; Liebel-Flarsheim, Cincinnati, OH) at a rate of 2.0 ml/s. Automated bolus tracking with bolus detection on the level of the ascending aorta assured accurate timing of the arterial phase. For display of the portal and hepatic venous anatomy, third and fourth CT image sets

Four steps are required for transferring the CT DICOM file into 3D digital liver using Hisense CAS: [1] upload the primary CT DICOM data into the Hisense CAS; [2] auto or semi-automatically reconstruct the liver structures (liver parenchyma, portal vein, hepatic veins, and tumors) in a 3D context by extraction of neighboring voxels with a similar CT density, and automatically calculate the total liver volume and tumor volume; [3] virtual liver resection using the software (automatically calculating the remnant liver volume); and [4] assessment of the optimal surgical procedures based on the virtual hepatectomy. The surgical team could communicate and discuss the surgical liver anatomy with radiologists or pediatricians based on 3D reconstruction, such as the tumor locations, the appearance of the vessel branches, or approach of liver resection. Various virtual surgical strategies could be explored in the Hisense CAS. Finally, the surgical team could develop the optimal plan of operation [7].

With the development of three-dimensional simulation software, it is possible to achieve virtual hepatectomy, which can assist the surgeons planning the operation. The development of threedimensional simulation software makes it possible to achieve virtual hepatectomy, which can assist surgeons to plan the operation, especially the complicated one. The history of 3D simulation software as it relates to hepatectomy can be divided into three stages: [1] successful 3D rendering of liver structures due to the introduction of multidetector row CT in the 1990s [20, 2] virtual hepatectomy depending on the reconstruction of the liver using 3D simulation software since 2000 [21, 3] the clinical practice and popularization of virtual hepatectomy using software packages since 2005, such as operation planning and operative navigation [22]. In some developed countries, such as Japan, virtual hepatectomy has routinely been performed in adult patients undergoing anatomic liver resection. It helps surgeons to plan the operative approach precisely, accurately position the lesion range, and be familiar with the operative route. Hisense Computer Assisted Surgery System (Hisense CAS) is a 3D simulation software package specifically developed for pediatric patients. It can provide precise and exquisite 3D visualization of pediatric liver structures using DICOM data from conventional CT. Considering that children have more refined anatomical structures, the accuracy of Hisense CAS was improved. Hepatectomy can be simulated on a personal computer, and the results can be shared with anyone in the cooperative team. Hisense CAS allows a surgeon to instantaneously manipulate the

**System (Hisense CAS)**

62 Liver Research and Clinical Management

With the development of medical imaging, 3D reconstruction technology, the innovation of liver surgery and the proposal of precision hepatectomy, the intrahepatic vascular anatomy of the liver and liver segmentectomy based on that vascular anatomy have become well developed. With the analysis of 3D digital liver, we proposed a new type of liver classification system: Dong's digital liver classification system. Professor Dong Qian of the Affiliated Hospital of Qingdao University analyzed the anatomy of thousands of digital human livers from newborns to the elderly to build a new system of liver classification based on intrahepatic vascular anatomy [24].

1260 cases of normal human liver were rendered into 3D digital livers using their DICOM files. Based on the anatomical variation of the portal branches supplying liver segments, we built our Dong's digital liver classification system.

We divided the digital liver into four groups based on the type of segmentation and the variations in portal vein anatomy. Type A livers are similar to Couinaud or Cho's segmentation, containing eight segments (**Figure 5**). Type B livers have nine segments because there are three subdivisions of right-anterior portal vein (**Figure 6**). The defining characteristic of Type C is the variation in the right-posterior portal vein, which is arcuate-shaped (**Figure 7**). Type C-a livers have arcuate-shaped right-posterior portal veins and right-anterior portal veins like those in Type A livers. Type C-b livers have arcuate-shaped right-posterior portal veins and right-anterior portal veins like those in Type B livers. Type D livers have anomalous portal vein variations, which require three-dimensional simulation and individualized liver resection plan (**Figure 8**).

**Type A**: Similar to Couinaud [25] or Cho's segmentation [26], containing eight segments (**Figure 5**).

**Segment I (3–6 P1 branches)**: Caudate lobe. There are 3–6 small branches (P1) originating from the back of right and left portal vein, surrounded by 5–8 tiny short hepatic veins.

**Segments II and III**: The left portal vein divides into the third-grade portal vein (P2 and P3) and perfuses the upper and lower outer sides of the left liver, which contains segments II and III.

**Segment IV**: Portal veins divided from the left portal vein perfuse the inner part of the left liver.

**Segments V and VIII**: The right portal vein divides into the right anterior and posterior branches, and then the anterior trunk further divides into several branches. (**Figure 5**).

**Segments VI and VII**: The right posterior portal vein further divides into right anterior (P6) and posterior branches (P7). The anterior branches perfuse segment VI, the lower outer area of the right liver.

**Type B:** Nine segments due to three subdivisions of right-anterior portal vein (**Figure 6**).

**Type C**: The right posterior portal vein does not divide into main branches as in Type A or B livers, whose portal veins separate into 5–11 branches from an arcuate trunk. During precise hepatectomy, it is difficult to resect only segments VI or VII as in Type A and Type B. The prevalence of Type C livers is not high, but it makes a considerable difference in precise surgery. Cases in which the right posterior portal vein is arcuate type and the right anterior portal vein separates into only P8 and P5 are defined as Type C-a (**Figure 7**). When the right posterior portal vein is arcuate type and the right anterior portal vein separate to P5, P8, and

Imaging Evaluation of Liver Tumors in Pediatric Patients http://dx.doi.org/10.5772/intechopen.73855 65

**Type D**: This is a catchall category, appearing in about 12.43% of all livers. It includes all

variations that cannot be classified into any of the previous three types (**Figure 8**).

**Figure 7.** Type C livers have arcuate-shaped right-posterior portal veins.

**Figure 8.** Rare variation of portal vein which is classified into Type D segmentation.

P9, we define it as Type C-b.

**Figure 5.** Right-anterior and right-posterior part of liver anatomy indicating Type A segmentation of Dong's digital liver classification system, similar to Couinaud or Cho's segmentation.

**Figure 6.** Right-anterior part of liver anatomy indicating Type B segmentation of Dong's digital liver classification system.

**Type C**: The right posterior portal vein does not divide into main branches as in Type A or B livers, whose portal veins separate into 5–11 branches from an arcuate trunk. During precise hepatectomy, it is difficult to resect only segments VI or VII as in Type A and Type B. The prevalence of Type C livers is not high, but it makes a considerable difference in precise surgery. Cases in which the right posterior portal vein is arcuate type and the right anterior portal vein separates into only P8 and P5 are defined as Type C-a (**Figure 7**). When the right posterior portal vein is arcuate type and the right anterior portal vein separate to P5, P8, and P9, we define it as Type C-b.

**Type D**: This is a catchall category, appearing in about 12.43% of all livers. It includes all variations that cannot be classified into any of the previous three types (**Figure 8**).

**Figure 7.** Type C livers have arcuate-shaped right-posterior portal veins.

**Figure 5.** Right-anterior and right-posterior part of liver anatomy indicating Type A segmentation of Dong's digital liver

**Figure 6.** Right-anterior part of liver anatomy indicating Type B segmentation of Dong's digital liver classification

classification system, similar to Couinaud or Cho's segmentation.

64 Liver Research and Clinical Management

system.

**Figure 8.** Rare variation of portal vein which is classified into Type D segmentation.
