Surgical Planning With Patient-specific Pancreaticobiliary Disease With 3D Models

2.1.Research Design This study group are general surgery residents present in Faculty of Medicine, Ege University (n=19). A quintet with stations composed of normal pancreaticobiliary anatomy, common bile duct tumor, stony cholecystitis, pancreatic head cancer and cholelithiasis is assembled for the study. Each station containes CT, 3D-STL images and 1:1 solid models of cases. Each imaging method (CT, 3D-STL image and 3D solid model) associated with the scenarios of the quintet is created in the residents of the study. An explanatory assessment measure is being used as data collection method where the perception of each imaging method is being investigated based on their effectiveness in problem identification as well as their efficiency in diverse diagnosis and pre-surgery organization.

2.2. Selection of the sample cases The patients are chosen among the CT examinations of the ones who referred to Ege University Faculty of Medicine, Department of General Surgery for diagnose and treatment between 2016 and 2018. CT archives are screened and 5 eligible patients (age: 18-62 year) who required hepatopancreatobiliary surgery were selected. Selection of the cases is based on patients with no previous hepatopancreatobiliary operation, pathology leading to dilated biliary duct, and whose radiological imaging results are suitable for modeling. Virtual modeling of pancreaticobiliary pathways of the cases is performed and clinical histories of each case were created.

2.3. Scenarios As a mutual agreement among the specialists in medical education, general surgery, anatomy and radiology, 5 cases identified, are elected to be samples for pancreaticobiliary surgical processes. Having defined these cases, they are further converted into genuine scenarios fully equipped with a past story, medical analysis results and imaging procedures.

Scenarios for 5 cases:

Case 1. Case with normal extrahepatic biliary tract with pancreas. Case 2. Choledochal tumor leading to advanced dilatation and hydropic gallbladder appearance in extrahepatic biliary tract.

Case 3. Acute cholecystitis characterized with extrahepatic biliary dilatation, hydropic gallbladder, thickness in gallbladder wall and biliary sludge with multiple millimeter-sized stones.

Case 4. Pancreatic head cancer with severe dilatation in the pancreatic canal and extrahepatic biliary tract.

Case 5. Choledocholithiasis characterized with dilatation at the extrahepatic biliary tract and 7 mm diameter stone at the distal end of the common bile duct.

2.4. Image post-processing and segmentation Original CT images in Digital Imaging and Communications in Medicine (DICOM) format are converted to a separate workstation with Analyze 12.0 for post-processing and segmentation. A free 3D slicer (version 4.10.1) is employed in the process of attaining DICOM output from CT and MRI segments of the patients. Special attention is paid to the anatomical structures of the biliary tract including left hepatic duct (LHD), right hepatic duct (RHD), and common hepatic duct (CHD) which are segmented. The surface condition of the model is enhanced by implementing a softening filter to the segmented section output. The output is extracted into STL format to enable 3D printing.

2.5. Creating Life-size Patient-Specific 3D Model 3D printers of Mass Portal Pharaoh xd 20 and Form Labs2 are employed throughout the process of preparing the models for printing.

2.6. Quantitative assessment of model accuracy To ensure the model accuracy, measurements of the anatomical landmarks are performed and compared at three stages of the model production, namely, the original CT images, STL file and 3D model. The internal diameter of four anatomical locations is measured from left to right and from anterior to posterior in the following landmarks: CHD, LHD, RHD and common bile ducts. .

2.7. Workshop We performed a systematic review to evaluate of bile tree modelization and 3D printing, as well as the proof of concept of the benefit of 3D solid model in planning interventions. CT images of a patient diagnosed with dilated extrahepatic ducts are used to create the patient-specific, 1-1 scale 3D pancreaticobiliary models including five scenarios as the normal anatomy, common bile duct tumor, stony cholecystitis, pancreatic head cancer and cholelithiasis. For this purpose, scenarios for each case and a five-station carousel are based on the research. For each station, a period of 5-10 minutes is given.

2.8. Survey Participants' perception of residency training is evaluated with a multi-entry survey. In these scenarios, normal pancreaticobiliary organs and cases leading to extrahepatic biliary tract dilatation such as choledochal tumor, acute stone cholecystitis, pancreatic head tumor and cholelithiasis are discussed. Assessment forms for the normal structure of the cases, differential diagnosis and imaging methods in preoperative planning and the location of the 3D solid model are prepared. The forms are then asked to be filled by the residents to discover their opinions on all models. The evaluaton is done on a scale of 10, where (01-10) defines 0 = very low and 10 = the highest rank.

2.9. Statistical analysis Analysis will be submitted into SPSS 24.0 for statistical evaluation mean ± standard deviation format is employed for continuous variables. Any significant differences in the measurements between the original CT images, 3D-STL images and the 3D model are studied by using Wilcoxon Signed Test. Wilcoxon Signed Ranks Test is used to determine any significant differences in the measurements between the original CT images, 3D-STL images and the 3D model. Statistical relevance is stated as a p value of less than 0.05.