| BackgroundWith the establishment of multi-dimensional value of modern surgery and the increasing of certainty in clinical practice, surgery has now entered into a new era of "Precision Surgery"."Precision Surgery" seeks the precise balance of maximization of lesion removal, maximization of organ sparing, and minimization of surgical trauma (3M). It is in this way that surgeons can find the balance point of the three objectives of therapeutic effectiveness, surgical safety, and minimal invasiveness (3Objectives,30), and achieve the maximized benefit and recovery for each patient.The deductive practice of the idea of "precision surgery" in the field of liver surgery is "Precision Liver Surgery", aimed at achieving the balance of "30" by maximizing the removal of the target lesion, maximizing the functional liver remnant and minimizing surgical invasiveness (3M in Precision Liver Surgery). The key points of surgery planning in Precision Liver Surgery mainly include:1. Determine the target lesion and region of obligatory liver resection;2. Determine the EFLV and obligatory extent of liver preservation;3. Determine the volume, structure and function of the liver remnant;4. Determine the optimal procedure of hepatectomy and the transection plane;5. Determine the vasculars to be resected and reconstructed.Through the three dimensional (3D) reconstruction of preoperative images, the computer-assisted surgery planning system (CASP) can restore the real spatial anatomic relationship between the lesions and its surrounding vasculature of importance, and help surgeons make surgery plans, virtual resections and risk assessment.To meet with requirements of surgery planning in Precision Liver Surgery, we used CASP to make preoperative surgery plans and risk assessment and validated the role of CASP in Precision Liver Surgery.Objective1. To evaluate the feasibility,3D visualization and accuracy by applying CASP to make preoperative surgery plans and risk assessment for patients undergoing liver resections.2. To validate the role of CASP in Precision Liver Surgery by comparing and verifying the two methods of two dimensional (2D) and3D surgery planning for patients undergoing liver resections.Methods221consecutive patients undergoing liver resections were prospectively involved in this study. Enhanced Multislice computed tomography (MSCT) or Magnetic Resonance Imaging (MRI) was performed with the slice thickness of1.25mm-1.5mm. All the images were stored and transferred in the format of digital imaging and communications in medicine (DICOM). For each patient, picture access and communication system (PACS) and CASP were applied respectively to make2D and3D surgery plans.2D surgery plan:Determine the extent of lesions and the relationship with surrouding vasculature, draw the transection line in2D images in PACS, calculate the liver remnant volume (LRV), the standard liver volume (SLV) and the odd ratio LRV/SLV. For normal parenchyma with no underlying disease, LRV/SLV should be no less than20%; for parenchyma with underlying disease including obstructive jaundice, cirrhosis, fatty liver, and chemotherapy induced liver injury, LRV/SLV should be no less than40%.3D surgery plan:Enhanced CT/MRI images were analyzed with the software IQQA-LIVER developed by Company of EDDA Technology (Princeton, USA). CASP extracted the anatomic information of the liver, the lesion and the intrahepatie vasculature and finished the3D reconstruction process. Determine the region of obligatory liver resection, the obligatory extent of liver preservation, the volume, structure and function of the liver remnant, the optimal procedure of hepatectomy, the optimal transection plane and the surgery risk (the vascular to be resected and reconstructed) and investigate measures for risk control.All the operations were separated into complex hepatectomy group and uncomplex hepatectomy group. The2D and3D surgery plans were compared and verified in each group.ResultsCASP can offer3D displays of the liver and the intrahepatie vasculature in an interactive way, including the portal vein, hepatic artery, hepatic vein and the dilated bile duct. CASP can restore the spatial anatomic relationship between the lesions and its surrounding vasculature of importance. CASP can also calculate the diameter and angle of each duct, the distance between two points, and territory volume of each vascular. The function of virtual resection of CASP enables surgeons to compare, select and optimize the surgery plan.Volume calculation:in uncomplex group, no significant differences were found between2D-LRV and3D-FLRV, no significant differences were found between2D-RV,3D-RV and specimen volume; in complex group, no significant differences were found between3D-RV and specimen volume.Territory analysis:for83cases of regular hepetectomy in complex group, coincidence rate of territory analysis and intraoperative ischemia/staining boundary was92.8%(77/83) and there were no differences between territory ananlysis and specimen volume.Operation result:203of221patients underwent liver resections successfully (91.9%), including102cases of uncomplex hepatectomy and101cases of complex hepatectomy. In uncomplex hepatectomy group,2D and3D made the same surgery plan in102cases (100%) and operations were successfully done according to the surgery plan in97cases. In complex hepatectomy group,3D and2D surgery plans were different in38cases (37.6%) and operations were successfully done according to the3D surgery plan. According to the significance of modification, the38different cases were classified into3grades in descending order:â… . Lesions are judged to be unresectable in2D surgery plan but resectable in3D surgery plan (5cases); â…¡.3D modifies the operation procedure of2D surgery plan(4cases); â…¢.3D modifies the resection extent of2D (29cases), including:â…¢a. Extended resection (19cases); â…¢b. Reduced resection (8cases); â…¢c. Combined with vascular reconstruction (2cases).Among the203cases undergoing hepatectomy, the mortality is0%, with a morbidity of16.7%. R0resection rate was100%in malignant tumor. The one year survival rate was100%in benign lesions and91.2%in malignant tumor.Conclusions1. The feasibility, accuracy and3D visualization of CASP system were validated. CASP can display the real spatial anatomy of the intrahepatic vasculature and the lesion in an interactive way, can obtain more anatomic information than conventional2D images, including the diameter and angle of each duct, the distance between two points, and territory volume of each vascular. CASP contributes to individualized operation and improves the certainty, predictability and controllability of surgery.2. CASP enables surgeons to compare, select and optimize the surgery plan, changes the procedure and resection extention of2D surgery plan, makes lesions unresectable in2D surgery plan tp be resectable, improves the therapeutic effectiveness, surgical safety and resectability.3. Through the spatial and quantitative assessment for intrahepatic vasculature, CASP contributes to the establishment of some standardized operation in uncomplex hepatectomy such as laparoscopically stapled left lateral sectionectomy, improving the standardization of surgery and decreasing the invasiveness.4. CASP improves the ability of CT/MRI review and spatial imagination for surgeons. |
