| BackgroundHepatolithiasis is a common disease with a distinct regional distribution. It often occurs in the residents living in the south to the Changjiang River, the coastal areas and the southwest area of China, especially in the rural areas. This disease has also a high incidence in the inhabitants of Southeast Asia and Japan. Hepatolithiasis, with a stubborn and highly recurrent nature, poses serious threat to the public health. The disease is often associated with different degrees of damages in the biliary system and liver cell and serious complications, and is an important cause of potentially fatal benign biliary disorders in China.In the1950s, Huang ZQ first reported their success of hepatectomy in the treatment hepatolithiasis, and it has been an important means for hepatolithiasis treatment ever since. At present, the treatment principle of hepatolithiasis is "removal of lesions, elimination of strictures, depletion of calculus, and complete bile drainage". Hepatolithiasis treatment mainly relies on surgical intervention, and surgical approaches include bile duct incision and lithotomy, partial hepatectomy, repair and reconstruction of bile duct stricture, and liver transplantation. Simple surgical stone extraction and biliary-enteric anastomosis has certain limitations. Hepatectomy is the most effective treatment for hepatolithiasis, and removes not only all the hepatic stones but also the associated pathologic bile ducts, including strictures, fibrosis, abscesses, and potentially carcinomatous bile ducts, thus decreasing the risk of recurrent intrahepatic stones. Nevertheless, the liver and its internal structure frequently have anatomical variations, and in patients with hepatolithiasis, the shape and anatomical position of the liver often undergo alterations accompanied often by vascular and biliary variations. The lack of full awareness of these anatomical is liable to cause injuries to the important intrahepatic ducts and leads to serious complications during the operation. On the other hand, because the calculi are deeply buried in hepatic parenchyma and usually intangible, and the position of the biliary stricture is highly variant, the conventional two-dimensional (2D) imaging modalities like CT and MRI often fail to accurately locate the calculi to cause difficulties in the diagnosis and treatment. Although hepatectomy can remove the lesions of the liver to maximally eliminate the calculi and biliary pathologies (stricture or dilation), this approach can not totally remove the stones and biliary stricture, which are the main factors for frequent recurrence and reoperation for hepatolithiasis after hepatectomy.In recent years, digital medical technology including three-dimensional (3D) reconstruction technique and visible simulation surgery technique has shown its important value in the diagnosis and treatment of liver tumor and liver transplantation and has made great achievements. The application of such techniques in biliary surgery, however, currently remains largely in the stage of laboratory researches, and their clinical applications are rarely reported. The3D visualization technique can accurately show the feature of calculus distribution and the anatomy of the intrahepatic structures including the stricture and other deformities of the bile duct system, which can significantly improve the accuracy of diagnosis. The visible simulation surgery technique can provide valuable assistance in making adequate surgical plan and selecting the optimal approaches for hepatectomy. This technique allows preoperative formulation of the optimal individualized surgical plan for the highly variant approaches of biliary surgery, thus help to achieve the therapeutic goals and reduce complications associated with the surgery, and ultimately improve the clinical outcomes of the patients. In this study, we collected the abdominal CT images from patients with hepatolithiasis as the source data for3D reconstruction and visible simulation surgery to guide the actual operation, and observed the anatomy and variations of the hepatic vein (HV) and portal vein (PV) in patients with hepatolithiasis. We assessed the application value of digital medical technology in guiding the surgeries for hepatolithiasis.Objectives1. To study the anatomy and variation of the hepatic vein and portal vein of patients with hepatolithiasis based on digital medical technology, then analyze their potential influence on the surgery.2. To assess the application value of digital medical technology in the diagnosis and surgical treatment of hepatolithiasis.3. To assess the application value of digital medical technology in the diagnosis and surgical reatment on complex hepatolithiasis.MethodsEquipment:(1)64-slice spiral CT-PHILIPS Brilliance64(Netherlands PHILIPS Company) and image post-processing workstation (PHILIPS Brilliance64own Mxview spiral CT workstation)(Imaging Center, Zhujiang Hospital, Southern Medical University), DICOM viewer, ACDSee10.0Image conversion software, abdominal3D medical image visualization system (MI-3DVS), virtual simulation surgery equipment system, and HP blade servers (Department of Clinical Digital Medical Research Center, Southern Medical University).Contrast agent:Ultravist (300mg I/ml) from Schering AG, Germany.ParticipantsA total of124patients with hepatolithiasis underwent surgical treatment assisted by3D technique between June2006and December2012in the Department of Hepatobiliary Surgery, Zhujiang Hospital. The inclusion criteria:Elective surgical patients; Patients with bile duct stones types Ⅰ,Ⅱa, and b (according to the guidelines of diagnosis and treatment of hepatolithiasis). The exclusion criteria:Patients undergoing emergency surgery; patients with bile duct stones types Ⅱc; Patients with concurrent cholangiocarcinoma. Among the124patients enrolled in this study, the gender ratio (M/F) was51/73, and the mean age was51.8±12.6years. Thirty-seven patients (29.8%) had comorbid conditions (such as cardiovascular disease, pulmonary disease, and diabetes mellitus),35(28.2%) had a history of biliary tract operations (including hepatectomy, choledocholithotomy, and bilioenteric anastomosis), and38(30.6%) had varying degrees of cholangitis manifestations such as fever, abdominal pain, and jaundice.Acquisition of upper abdominal CT dataAbdominal CTA was carried out with the tube voltage of120KV, tube current of300mAs,0.5s per lap, pitch0.984, and slice thickness of5mm. The scan was divided into4phases:precontrast, arterial phase, portal phase, and delayed phase. The image data was cut from a slice thickness of5mm to1mm after scanning. In enhanced scanning, the contrast agent was injected at the rate of5ml/s, and each scan time was5s. According to the measurement of the peak of aortic agent contrast, the arterial phase scan was automatically triggered, with the first scan time of usually20-25s after the start of injection of agent contrast; the door pulse of the scan time was generally at the50-55s; the portal venous phase scan started immediately after the delayed phase scan. The image data was transported to the Mxview image post-processing workstation.To obtain high-quality data for the liver and the intrahepatic ductal system, in enhanced CT scanning, the scan was ensured to initiate within the peak enhancement of the target vessel so as to improve the quality of vascular imaging and the quality of the raw data for3D reconstruction.High-quality CT image data of the stones, dilation or stricture of bile duct were acquired by0.625mm ultra-thin layer scanning.CT image data collectionIn Mxview image post-processing workstation, the image data of the4scanning phases were transmitted to HP blade servers of our Clinical Medicine Department of the Graduate Center, exported and saved.Image segmentationThe format of the two-dimensional image data batch were converted via DICOM Viewer followed by image adjustment by ACDSee10.0image conversion software. The data were then imported into MI-3DVS for fast image segmentation for reconstruction of the3D models. The productions of STL (STereo Lithography) format of the liver, hepatic artery, portal vein, hepatic vein and inferior vena cava, biliary and calculus, and automatic registration was carried after the completion of each model.3D reconstructionThe productions of STL (STereo Lithography) format were imported to FreeForm Modeling System for smoothing before3D reconstruction. The smoothed3D models of the various organs were configured into a3D reconstructed abdominal model containing the organs and tissues. The3D model and its components allowed manipulations of zooming, rotation, and transparent rendering to examine the anatomical relations of the tissue structures and display the calculi distribution, bile duct stricture and deformity, vascular arrangement, and parenchymal lesions from multiple directions, angles, and levels.Classification of the HV and PVThe classification of HV was based on the relationship between the three major HVs and the inferior vena cava (IVC), the variations of the3HVs, and the presence of other uncommon HVs. Based the methods of Couinaud, combined with3D model of the individual patient, the intrahepatic portal vein branch is divided into the following types:normal type, type I variation, type II variation, type III variation, and other variation.Classification of hepatolithus diagnosisBy adjusting the transparency of the3D model, the the position, size, morphology and distribution of the stones, and the site, length and degree of bile duct stricture were displayed to classify the diagnosis according to the guidelines of diagnosis and treatment of hepatolithiasisIndividualized liver segmentationBased on the3D models of liver, portal vein, hepatic vein and bile duct, the segmentation of the liver was carried out using the portal veins as the landmarks, the hepatic veins as the boundary marks, and the gall bladder and ligament as the auxiliary segmentation marks. Each segment of the liver was supplied by an independent branch of the portal vein. For segmentation of the liver and location diagnosis of the lesion, the anatomy of the portal veins and the relationship between the lesion and portal veins are more important. Normally, the branches steming from the main trunk of the portal vein was defined as the first level branch, and the part of the liver supplied by a third-level branch of the portal veins was defined as one hepatic segment. Thus we divided the liver into1to10hepatic segments named with the Roman numerals from I to X. Because the Gelisson system contains the portal veins and bile duct, we could make an accurate location diagnosis of hepatolithiasis and cholangiectasis or stenosis of the bile duct.Measurement of the liver volumeThe3D model of the liver was imported to the MI-3DVS software for simulation of surgical cutting. The liver as a whole, the resected liver and the residual liver volumes were estimated respectively, and the percentages of resected and residual liver volumes in the total liver volume were calculated to assess the safety of the preoperative surgical plan for patients requiring liver resection.Simulation surgeryThe3D reconstruction models were imported to the FreeForm Modeling System to perform a variety of simulation surgery to determine the optimal approaches for the actual surgery.Actual surgery:The consistency between the actual hepatectomy and the simulation surgery was evaluated. Intraoperative cholangioscopy was routinely used for visualizing the residual stones and ductal strictures. A T-tube was routinely inserted for postoperative cholangiography or cholangioscopy. Postoperative cholangiography or cholangioscopy were performed to detect the residual stones and ductal strictures. Ultrasonography or CT follow-up was conducted every6months or1year, or whenever the patients presented with symptoms suggestive of cholangitis. The medical records of the patients for preoperative general characteristics, operation conditions, immediate outcomes, long-term outcomes were compared to assess the value of the3D technique in guiding hepatectomy for hepatolithiasis.Evaluation indexes:①The display accuracy of the3D model for the intrahepatic anatomy, and the coincidence rate of the simulation surgery and the actual surgery were assessed.②The effect of the anatomical variation of the HVs and PVs on the surgery of hepatolithiasis was evaluated.③The medical records of the patients including the operating time, length of postoperative hospital stay, estimated blood loss, the volume of blood transfusion, calculus depletion rate, and the immediate and long-term complications were analyzed to assess the value of digital medical technology in guiding the operation for hepatolithiasis.Statistical MethodsThis study did not involve any sophisticated statistical analysis methods apart from the calculation of the percentages.Results3D reconstruction and classification diagnosis3D reconstruction models clearly displayed all the structures, including the bile ducts, hepatic artery, hepatic vein, portal vein, and calculi, which were consistent with the findings in the operations. Classification diagnosis according to the3D model found that among the124patients,66had type I,19had type Ⅱa,39had type Ⅱb hepatolithiasis.52.4%of the patients had stone in the common bile duct, and38.7%had bile duct stricture. Anatomy and variation of HV and PVRelationship of HV to IVC:22.6%of the patients had the right, middle, and left hepatic vein draining independently into the IVC.67.7%of patients had the prevailing pattern that the3hepatic veins included a RHV with the MHV and LHV sharing a common trunk.9.7%of the patients who were free of a previous hepatectomy showed the presence of a LHV. Variations in the right hepatic vein: The prevailing pattern of RHV was found in42.7%, small RHV with a large inferior RHV in21.0%, small RHV with an accessory RHV in7.3%, and small RHV compensated by a well developed MHV in29.0%of the patients. Variations in the middle hepatic vein:The prevailing pattern of the MHV was found in73.4%, segment4vein (Sg4V) joining the MHV in17.7%, and Sg4V joining the IVC independently in8.9%of the patients. Variations in the left hepatic vein:the prevailing pattern of LHV was found in76.6%, Sg4V joining the LHV in13.7%, and absence of the LHV in9.7%of the patients.The normal type of the PV was found in67.7%, type Ⅰ variation in8.9%, type Ⅱ variation in7.3%, type Ⅲ variation in12.1%and other variations in4.0%of the patients. In the5cases with other variations of the PV, one had atrophic right posterior branch of the PV, and the right anterior branch and the left PV with a common trunk gave rise to some branches to dominate the segment Ⅳ of the liver. In another case, the branches of the caudate lobe were well developed, and the branches of the right PV showed obvious atrophy. In the third case, only one trunk without the right and left PV directly gave rise to the branches in the left lateral, segment Ⅳ, and the right liver. In the fourth case, the branches in the segments Ⅴ and Ⅷ were directly stemmed from the right PV. The fifth case had no trunk of the right posterior branch of the PVwith an atrophic branch of the LPV, and the end of the RPV directly separated the right anterior branch and the segments Ⅵ and Ⅶ portal vein branch. Atrophy of the branches of the PV was a common finding. In this study,33.9%of the cases had varying degrees of atrophy of the branches of PV.Simulation surgeryUsing the force feedback device PHANTOM and the virtual surgical instruments, each type of the simulation surgery could be easily performed, including bile duct exploration lithotomy and liver resection. The individualized liver segmentation could accurately locate the position of the stones and bile duct stricture, and preoperative volume measurement allowed accurate estimate of the residual liver volume after hepatectomy to avoid postoperative liver failure. The anatomical relationship of the important vessels, bile duct and calculi could be observed by screening the liver resection plane during the simulation surgery. The optimal surgical plan was determined by the optimization of the multiple surgery programs. As a result,21of the124cases underwent bile duct exploration lithotomy and103underwent hepatic resection.Surgical outcomesAmong the124patients,21received bile duct exploration lithotomy and103underwent hepatic resection, and the consistency rate between the actual hepatectomy protocols and the preoperative surgical plan was100%. In31.5%of cases hepaticojejunostomy was performed. The postoperative hospital stay averaged11.7±3.7days with a mean estimated blood loss of446.7±181.8ml. Forty-eight cases required blood transfusion in the operation with a transfusion volume of420.8±211.3ml and average operating time of234.7±40.0min. The total incidence of immediate complications was13.7%, and the rate of residual calculus was0.8%. Of the124patients, the average follow-up was38.4±18.3months; the rate of patients with recurrent stone was2.4%and4cases showed symptoms of recurrence. The total incidence of long-term complications was5.6%.Among the41patients with complex hepatolithiasis, the average operating time was265.4±38.9min, the mean postoperative hospital stay was13.1±4.9days, and the estimated blood loss was596.4±178.6ml. Twenty-three cases needed blood transfusion in the operation, with a blood transfusion volume of200-800ml. The total incidence of immediate complications was19.5%, and the rate of calculus depletion was97.6%. Of the41patients, the average follow-up was35.6±15.9months, the rate of patients with recurrence stone was2.4%, and2cases had symptoms of recurrence. The total incidence of long-term complications was9.8%in these41patients.Conclusion:1. The anatomy and variation of HV and PV in patient with hepatolithiasis can be complicated, and the reconstructed3D model can clearly display the variations to avoid surgical risk by optimizing the surgical plan, hence improve the surgical safety.2. Digital medical technology in guiding the surgery for hepatolithiasis can effectively reduce the surgical complications and improve the outcomes, demonstrating its potential as a novel means for surgical treatment of hepatolithiasis.3. Digital medical technology can clearly demonstrate the previous surgical procedures and the consequent changes in the anatomic structure in patients with recurrent hepatolithiasis, thus helping to reduce the surgical difficulty. Adequate preoperative surgical planning can effectively reduce the rate of reoperation.4. In cases of multiple calculi in the bilateral lobes of the liver to require multiple liver resection, digital medical technology can help to determine the optimal surgical plan allowing preoperative practice and modification of the surgical plan to maximally improve the success rate of surgery and promote the recovery of patients after operation. |
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