Development of a Patient-Specific 3D-Printed Liver Model for Preoperative Planning

Abstract

IntroductionLiver surgery is widely used as a treatment modality for various liver pathologies. Despite significant improvement in clinical care, operative strategies and technology over the last few decades, liver surgery is still risky and optimal preoperative planning and anatomical assessment are necessary to minimize risks of serious complications. 3D printing technology is rapidly expanding and its applications in medicine are growing, but its applications in liver surgery are still limited. This article describes development of models of hepatic structures specific to a patient diagnosed with an operable hepatic malignancy. MethodsAnatomy data was segmented and extracted form CT and MRI liver of a single patient with a resectable liver tumour. The digital data of the extracted anatomical surfaces was then edited and smoothed resulting in a set of digital 3D models of the hepatic vein, portal vein with tumour, biliary tree with gallbladder and hepatic artery. These were then 3D printed. ResultsThe final models of the liver structures and tumour is provide good anatomical detail and representation of the spatial relationships between the liver tumour and adjacent hepatic structures. It can be easily manipulated and explored from different angles. ConclusionsA graspable, patient specific, 3D printed models of liver structures could provide an improved understanding of the complex liver anatomy, better navigation in difficult areas and allow surgeons to anticipate anatomical issues that might arrive during the operation. Further research into adequate imaging, liver specific volumetric software, and segmentation algorithms are worth considering to optimize this application. Methods Data Extraction and SegmentationRetrospectively collected radiology image data from a patient with an operable malignant hepatic tumour consisted of a standard CT angiogram of abdomen and pelvis and MRI of liver performed using a standard hepatic imaging protocol with gadolinium contrast. The CT slides were 3mm thick and MRI slides were 8.99 mm thick, both yielding anisotropic voxels when viewed as 3D. The data of both scans was stored in Digital Imaging and Communications in Medicine (DICOM) files. Amira 4.5.4. visualisation software (FEI, Hillsboro, USA) was used to view and segment the data. All scans were interrogated in three planes and pixels containing image data for hepatic and portal veins, hepatic artery, biliary structures and tumour were manually selected. (Figure 1). Due to varying image quality between the two radiology modalities used, MRI data was used to segment the biliary tree, portal vein, hepatic veins and tumour, whilst the CT was used to collect data for the hepatic artery. Segmentation was completed with a combination of manual, and "region growing"techniques, where the latter was used for large regions of similar density signal. Surgical InnovationMadurska, Poyade, Eason, Rea, Watson/ Development of patient specific 3D printed liver 5 model for preoperative planning Surface extraction and model pr...

Patient-specific three-dimensional printing for pre-surgical planning in hepatocellular carcinoma treatment

“…Although the segmentation, editing, and 3D printing processes are all considered as possible influential factors contributing to the observed variance, it is logical to surmise that the difference was largely influenced by the segmentation and editing process (10,22), with the mean difference in CT and STL file measurements being greater than that of the STL and 3D liver model measurements.…”

“…3D printed liver models have been found to enhance the viewer's understanding of highly variable and complex hepatic anatomy (13,14,16,18,22). There are a number of case studies that deem 3D printed liver models to be useful clinical tools in pre-and perioperative processes for the resection of liver lesions and in living donor liver transplant procedures (3,6,9,13,16,23).…”

“…Physical 3D modelling has been identified to support efficient and effective perception of positional and structural information through the direct visualization of anatomy and pathology (2,3,9,13,14,16,22,25). This ultimately surpasses the need for mental 3D reconstruction involved when attempting to understand 2D images (29), which may be considered particularly valuable in the case of HCC due to the relative complexity of hepatic anatomy and pathological characteristics associated with certain HCC lesions (1,5).…”

“…Image visualization and processing tools within this software were used to (I) apply a median filter, reducing image noise and enhancing the anatomical boundaries for accurate segmentation; (II) segment structures of interest; and (III) export the segmented data in standard tessellation language (STL) file format as required for editing and 3D printing (10,16,18,(22)(23)(24)(25). Anatomical structures that were perceived likely to affect decisions made in surgical planning included the inferior vena cava, portal vein and associated branches, hepatic veins, hepatic artery, the tumour and associated arterial supply, and the liver body (2,3,9,23).…”

“…Currently, 3D printed models are being used as clinical tools in the endeavour to bridge this gap, enhancing the viewer's cognitive comprehension of anatomy and pathology in areas such as medical education, surgical training, surgical planning and operative simulation (2,3,(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The tactile experience is known to support a holistic evaluation of important anatomical and/or pathological features (10), with the manipulation and visualization of the physical 3D printed models providing the in-depth understanding required to plan accurate, safe, and effective surgical procedures (4,5,13,14,16,(17)(18)(19)(20)(21).3D printed liver models have been found to enhance the viewer's understanding of highly variable and complex hepatic anatomy (13,14,16,18,22). There are a number of case studies that deem 3D printed liver models to be useful clinical tools in pre-and perioperative processes for the resection of liver lesions and in living donor liver transplant procedures (3,6,9,13,16,23).…”