The impact of 3-dimensional reconstructions on operation planning in liver surgery

International multidisciplinary consensus recommendations on clinical application of three-dimensional visualization in precision surgery for pediatric liver tumors

BACKGROUND

Pediatric liver tumors are predominantly primary malignant tumors, and complete tumor resection with sufficient preservation of liver tissue is crucial for improving prognosis. However, due to the delicate anatomical structure of the pediatric liver and the relatively large size of the tumors, especially in difficult cases, the surgical challenges are substantial. While precision liver surgery are widely applied in clinical practice, pediatric cases require more customized approaches. The application of three-dimensional (3D) visualization technology is crucial for enhancing surgical accuracy, allowing for precise preoperative planning and intraoperative guidance.

METHODS

This consensus was collaboratively developed by 36 experts from eight countries, using the Glaser's state-of-the-art method to review and refine the draft.

RESULTS

The final consensus resulted in 15 international multidisciplinary consensus recommendations on clinical application of 3D visualization in precision surgery for pediatric liver tumors.

CONCLUSION

This consensus will standardize the application of 3D visualization technology in precision surgery for pediatric liver tumors to improve outcomes and reduce risks.

Computer-assisted three-dimensional individualized extreme liver resection for hepatoblastoma in proximity to the major liver vasculature

BACKGROUND

The management of hepatoblastoma (HB) becomes challenging when the tumor remains in close proximity to the major liver vasculature (PMV) even after a full course of neoadjuvant chemotherapy (NAC). In such cases, extreme liver resection can be considered a potential option.

AIM

To explore whether computer-assisted three-dimensional individualized extreme liver resection is safe and feasible for children with HB who still have PMV after a full course of NAC.

METHODS

We retrospectively collected data from children with HB who underwent surgical resection at our center from June 2013 to June 2023. We then analyzed the detailed clinical and three-dimensional characteristics of children with HB who still had PMV after a full course of NAC.

RESULTS

Sixty-seven children diagnosed with HB underwent surgical resection. The age at diagnosis was 21.4 ± 18.8 months, and 40 boys and 27 girls were included. Fifty-nine (88.1%) patients had a single tumor, 39 (58.2%) of which was located in the right lobe of the liver. A total of 47 patients (70.1%) had PRE-TEXT III or IV. Thirty-nine patients (58.2%) underwent delayed resection. After a full course of NAC, 16 patients still had close PMV (within 1 cm in two patients, touching in 11 patients, compressing in four patients, and showing tumor thrombus in three patients). There were 6 patients of tumors in the middle lobe of the liver, and four of those patients exhibited liver anatomy variations. These 16 children underwent extreme liver resection after comprehensive preoperative evaluation. Intraoperative procedures were performed according to the preoperative plan, and the operations were successfully performed. Currently, the 3-year event-free survival of 67 children with HB is 88%. Among the 16 children who underwent extreme liver resection, three experienced recurrence, and one died due to multiple metastases.

CONCLUSION

Extreme liver resection for HB that is still in close PMV after a full course of NAC is both safe and feasible. This approach not only reduces the necessity for liver transplantation but also results in a favorable prognosis. Individualized three-dimensional surgical planning is beneficial for accurate and complete resection of HB, particularly for assessing vascular involvement, remnant liver volume and anatomical variations.

Polarization-sensitive optical coherence tomography for renal tumor detection in ex vivo human kidneys

Kidney cancer is a kind of high mortality cancer because of the difficulty in early diagnosis and the high metastatic dissemination in treatments. The surgical resection of tumors is the most effective treatment for renal cancer patients. However, precise assessment of tumor margins is a challenge during surgical resection. The objective of this study is to demonstrate an optical imaging tool in precisely distinguishing kidney tumor borders and identifying tumor zones from normal tissues to assist surgeons in accurately resecting tumors from kidneys during the surgery. 30 samples from six human kidneys were imaged using polarization-sensitive optical coherence tomography (PS-OCT). Cross-sectional, enface, and spatial information of kidney samples were obtained for microenvironment reconstruction. Polarization parameters (phase retardation, optic axis direction, and degree of polarization uniformity (DOPU) and Stokes parameters (Q, U, and V) were utilized for multi-parameter analysis. To verify the detection accuracy of PS-OCT, H&E histology staining and dice-coefficient was utilized to quantify the performance of PS-OCT in identifying tumor borders and regions. In this study, tumor borders were clearly identified by PS-OCT imaging, which outperformed the conventional intensity-based OCT. With H&E histological staining as golden standard, PS-OCT precisely identified the tumor regions and tissue distributions at different locations and different depths based on polarization and Stokes parameters. Compared to the traditional attenuation coefficient quantification method, PS-OCT demonstrated enhanced contrast of tissue characteristics between normal and cancerous tissues due to the birefringence effects. Our results demonstrated that PS-OCT was promising to provide imaging guidance for the surgical resection of kidney tumors and had the potential to be used for other human kidney surgeries in clinics such as renal biopsy.

Intraoperative artificial intelligence system identifying liver vessels in laparoscopic liver resection: a retrospective experimental study

BACKGROUND

The precise recognition of liver vessels during liver parenchymal dissection is the crucial technique for laparoscopic liver resection (LLR). This retrospective feasibility study aimed to develop artificial intelligence (AI) models to recognize liver vessels in LLR, and to evaluate their accuracy and real-time performance.

METHODS

Images from LLR videos were extracted, and the hepatic veins and Glissonean pedicles were labeled separately. Two AI models were developed to recognize liver vessels: the "2-class model" which recognized both hepatic veins and Glissonean pedicles as equivalent vessels and distinguished them from the background class, and the "3-class model" which recognized them all separately. The Feature Pyramid Network was used as a neural network architecture for both models in their semantic segmentation tasks. The models were evaluated using fivefold cross-validation tests, and the Dice coefficient (DC) was used as an evaluation metric. Ten gastroenterological surgeons also evaluated the models qualitatively through rubric.

RESULTS

In total, 2421 frames from 48 video clips were extracted. The mean DC value of the 2-class model was 0.789, with a processing speed of 0.094 s. The mean DC values for the hepatic vein and the Glissonean pedicle in the 3-class model were 0.631 and 0.482, respectively. The average processing time for the 3-class model was 0.097 s. Qualitative evaluation by surgeons revealed that false-negative and false-positive ratings in the 2-class model averaged 4.40 and 3.46, respectively, on a five-point scale, while the false-negative, false-positive, and vessel differentiation ratings in the 3-class model averaged 4.36, 3.44, and 3.28, respectively, on a five-point scale.

CONCLUSION

We successfully developed deep-learning models that recognize liver vessels in LLR with high accuracy and sufficient processing speed. These findings suggest the potential of a new real-time automated navigation system for LLR.

Recent advances in computerized imaging and its vital roles in liver disease diagnosis, preoperative planning, and interventional liver surgery: A review

The earliest and most accurate detection of the pathological manifestations of hepatic diseases ensures effective treatments and thus positive prognostic outcomes. In clinical settings, screening and determining the extent of a pathology are prominent factors in preparing remedial agents and administering appropriate therapeutic procedures. Moreover, in a patient undergoing liver resection, a realistic preoperative simulation of the subject-specific anatomy and physiology also plays a vital part in conducting initial assessments, making surgical decisions during the procedure, and anticipating postoperative results. Conventionally, various medical imaging modalities, e.g., computed tomography, magnetic resonance imaging, and positron emission tomography, have been employed to assist in these tasks. In fact, several standardized procedures, such as lesion detection and liver segmentation, are also incorporated into prominent commercial software packages. Thus far, most integrated software as a medical device typically involves tedious interactions from the physician, such as manual delineation and empirical adjustments, as per a given patient. With the rapid progress in digital health approaches, especially medical image analysis, a wide range of computer algorithms have been proposed to facilitate those procedures. They include pattern recognition of a liver, its periphery, and lesion, as well as pre- and postoperative simulations. Prior to clinical adoption, however, software must conform to regulatory requirements set by the governing agency, for instance, valid clinical association and analytical and clinical validation. Therefore, this paper provides a detailed account and discussion of the state-of-the-art methods for liver image analyses, visualization, and simulation in the literature. Emphasis is placed upon their concepts, algorithmic classifications, merits, limitations, clinical considerations, and future research trends.

How Much Is Enough? A Surgical Perspective on Imaging Modalities to Estimate Function and Volume of the Future Liver Remnant before Hepatic Resection

Liver resection is the first curative option for most hepatic primary and secondary malignancies. However, post-hepatectomy liver failure (PHLF) still represents a non-negligible postoperative complication, embodying the most frequent cause of hepatic-related mortality. In the absence of a specific treatment, the most effective way to deal with PHLF is its prevention through a careful preoperative assessment of future liver remnant (FLR) volume and function. Apart from the clinical score and classical criteria to define the safe limit of resectability, new imaging modalities have shown their ability to assist surgeons in planning the best operative strategy with a precise estimation of the FLR amount. New technologies leading to liver and tumor 3D reconstruction may guide the surgeon along the best resection planes combining the least liver parenchymal sacrifice with oncological appropriateness. Integration with imaging modalities, such as hepatobiliary scintigraphy, capable of estimating total and regional liver function, may bring about a decrease in postoperative complications. Magnetic resonance imaging with hepatobiliary contrast seems to be predominant since it simultaneously integrates hepatic function and volume information along with a precise characterization of the target malignancy.

Full-sized realistic 3D printed models of liver and tumour anatomy: a useful tool for the clinical medicine education of beginning trainees

BACKGROUND

Simulation-based medical education (SBME) and three-dimensional printed (3DP) models are increasingly used in continuing medical education and clinical training. However, our understanding of their role and value in improving trainees' understanding of the anatomical and surgical procedures associated with liver surgery remains limited. Furthermore, gender bias is also a potential factor in the evaluation of medical education. Therefore, the aim of this study was to evaluate the educational benefits trainees receive from the use of novel 3DP liver models while considering trainees' experience and gender.

METHODS

Full-sized 3DP liver models were developed and printed using transparent material based on anonymous CT scans. We used printed 3D models and conventional 2D CT scans of the liver to investigate thirty trainees with various levels of experience and different genders in the context of both small group teaching and formative assessment. We adopted a mixed methods approach involving both questionnaires and focus groups to collect the views of different trainees and monitors to assess trainees' educational benefits and perceptions after progressing through different training programs. We used Objective Structured Clinical Examination (OSCE) and Likert scales to support thematic analysis of the responses to the questionnaires by trainees and monitors, respectively. Descriptive analyses were conducted using SPSS statistical software version 21.0.

RESULTS

Overall, a 3DP model of the liver is of great significance for improving trainees' understanding of surgical procedures and cooperation during operation. After viewing the personalized full-sized 3DP liver model, all trainees at the various levels exhibited significant improvements in their understanding of the key points of surgery (p < 0.05), especially regarding the planned surgical procedure and key details of the surgical procedures. More importantly, the trainees exhibited higher levels of satisfaction and self-confidence during the operation regardless of gender. However, with regard to gender, the results showed that the improvement of male trainees after training with the 3DP liver model was more significant than that of female trainees in understanding and cooperation during the surgical procedure, while no such trend was found with regard to their understanding of the base knowledge.

CONCLUSION

Trainees and monitors agreed that the use of 3DP liver models was acceptable. The improvement of the learning effect for practical skills and theoretical understanding after training with the 3DP liver models was significant. This study also indicated that training with personalized 3DP liver models can improve all trainees' presurgical understanding of liver tumours and surgery and males show more advantage in understanding and cooperation during the surgical procedure as compared to females. Full-sized realistic 3DP models of the liver are an effective auxiliary teaching tool for SBME teaching in Chinese continuing medical education.

Preliminary study of 3D printing technology for extracorporeal positioning guide assisted ultrasound-guided microwave ablation of the liver

BACKGROUND

We designed a 3D-printed extracorporeal positioning guide for assisting ultrasound-guided microwave ablation of the liver and observed its effectiveness.

RESEARCH DESIGN AND METHODS

13 patients with liver cancer were selected, and their CT data were obtained. The CT data is reconstructed in 3D by computer software Mimics to create a 3D model. The 3D-printed in vitro positioning guides were designed by 3-Matic and fabricated using 3D printing technology. Finally, it is applied to the clinic, and its effect is observed.

RESULTS

The preliminary design of a 3D printed extracorporeal positioning guide was applied to the clinic, and the efficiency of assisted ultrasound positioning was 76.92% (10/13), with three patients requiring repositioning. The efficiency of the 3D printed extracorporeal positioning guide technique was 76.92%, a CT examination was performed one month after surgery, and three patients had residual lesions.

CONCLUSIONS

3D-printed extracorporeal positioning guides can assist ultrasound in localizing tumors during liver microwave ablation and reduce repeated punctures. It makes percutaneous microwave ablation of the liver more precise and safe. However, the current study sample is small, there are still apparent shortcomings, and long-term clinical studies are needed to prove its effectiveness.

A Bibliometric Analysis of the Role of 3D Technology in Liver Cancer Resection

BACKGROUND

Liver cancer resection is an effective but complex way to treat liver cancer, and complex anatomy is one of the reasons for the difficulty of surgery. The use of 3D technology can help surgeons cope with this dilemma. This article intends to conduct a bibliometric analysis of the role of 3D technology in liver cancer resection.

METHODS

(TS = (3D) OR TS = (three-dimensional)) AND (TS = (((hepatic) OR (liver)) AND ((cancer) OR (tumor) OR (neoplasm)))) AND (TS = (excision) OR TS = (resection)) was used as a search strategy for data collection in the Web of Science (WoS) Core Collection. CiteSpace, Carrot2 and Microsoft Office Excel were used for data analysis.

RESULTS

Three hundred and eighty-eight relevant articles were obtained. Their annual and journal distribution maps were produced. Countries/regions and institutions collaboration, author collaboration, references co-citations and their clusters and keywords co-occurrences and their clusters were constructed. Carrot2 cluster analysis was performed.

CONCLUSIONS

There was an overall upward trend in the number of publications. China's contribution was greater, and the USA had greater influence. Southern Med Univ was the most influential institution. However, the cooperation between institutions still needs to be further strengthened. Surgical Endoscopy and Other Interventional Techniques was the most published journal. Couinaud C and Soyer P were the authors with the highest citations and centrality, respectively. "Liver planning software accurately predicts postoperative liver volume and measures early regeneration" was the most influential article. 3D printing, 3D CT and 3D reconstruction may be the mainstream of current research, and augmented reality (AR) may be a future hot spot.

The value of three-dimensional visualization techniques in hepatectomy for complicated hepatolithiasis: A propensity score matching study

OBJECTIVE

The present study aimed to investigate the safety, feasibility, and efficacy of three-dimensional visualization technique (3DVT)-guided hepatectomy in the treatment of complicated hepatolithiasis.

METHODS

The clinical and follow-up data of 279 patients with complicated hepatolithiasis were retrospectively analyzed. The patients were divided into a 3DVT group (group A, 66 cases) and a non-3DVT group (group B, 213 cases). After baseline data were balanced using propensity score matching (PSM), the clinical characteristics and follow-up data of the two groups were observed.

RESULTS

After 1:1 PSM, 58 patients in each group were successfully matched with each other. When the groups were compared, the surgical duration (p = 0.033) and intraoperative blood loss (p = 0.002) of group A were lower than those of group B. The immediate stone clearance rate (91.4% vs. 75.9%, p = 0.024) and quality of life outcome (p = 0.034) of group A were significantly higher than those of group B. Logistic regression analysis showed that history of two or more biliary tract operations (odds ratio [OR] = 6.544, 95% confidence interval [CI] = 1.193-35.890, p = 0.031), bilateral stone distribution (OR = 4.198, 95% CI = 1.186-14.854, p = 0.026), and Geng grade III or IV (OR = 12.262, 95% CI = 2.224-67.617, p = 0.004) were independent risk factors for poor outcomes in patients with complicated hepatolithiasis.

CONCLUSION

Compared to conventional imaging examinations, 3DVT can be used to guide and achieve accurate preoperative diagnosis of complicated hepatolithiasis and has good safety, feasibility, and efficacy.

Effectiveness of an immersive virtual reality environment on curricular training for complex cognitive skills in liver surgery: a multicentric crossover randomized trial

BACKGROUND

Virtual reality (VR) is increasingly used in surgical education, but evidence of its benefits in complex cognitive training compared to conventional 3-dimensional (3D) visualization methods is lacking. The objective of this study is to assess the impact of 3D liver models rendered visible by VR or desktop interfaces (DIs) on residents' performance in clinical decision-making.

METHOD

From September 2020 to April 2021, a single-blinded, crossover randomized educational intervention trial was conducted at two university hospitals in Belgium and Italy. A proficiency-based stepwise curriculum for preoperative liver surgery planning was developed for general surgery residents. After completing the training, residents were randomized in one of two assessment sequences to evaluate ten real clinical scenarios.

RESULTS

Among the 50 participants, 46 (23 juniors/23 seniors) completed the training and were randomized. Forty residents (86.96%) achieved proficiency in decision-making. The accuracy of virtual surgical planning using VR was higher than that using DI in both groups A (8.43 ± 1.03 vs 6.86 ± 1.79, p < 0.001) and B (8.08 ± 0.9 vs 6.52 ± 1.37, p < 0.001).

CONCLUSION

Proficiency-based curricular training for liver surgery planning successfully resulted in the acquisition of complex cognitive skills. VR was superior to DI visualization of 3D models in decision-making.

CLINICALTRIALS

GOV ID

NCT04959630.

Laparoscopic Resection of Synchronous Liver Metastasis Involving the Left Hepatic Vein and the Common Trunk Bifurcation: A Strategy of Parenchyma-Sparing Resection with Left Sectionectomy and 4a Subsegmentectomy by Arantius Approach

When colorectal cancer presents with liver metastasis, hepatic resection remains the most important factor in prolonging survival, and new paradigms have been proposed to augment resectability. An adequate liver remnant and vascularisation are the only limits in complex liver resection, and parenchyma-sparing surgery is a strategy for minimising the complications, preserving liver function, and allowing patients to undergo further liver resection. The laparoscopic approach represents a new challenge, especially when lesions are located in the superior or posterior part of the liver. We discuss the case of an 81-year-old patient with a single synchronous liver metastasis involving the left hepatic vein and leaning into the middle hepatic vein at the common trunk, where we performed a simultaneous laparoscopic colonic resection with a left sectionectomy extended to segment 4a. The strategic approach to the Arantius ligament by joining the left and middle hepatic vein allowed us to avoid a major liver hepatectomy, preserve the liver parenchyma, reduce complications, enhance patient recovery, and perform the entire procedure by laparoscopy. Our example suggests that the Arantius approach to the left hepatic vein and the common trunk could be a feasible approach to consider in laparoscopic surgery for lesions located in their proximity.

3D Reconstruction Methods Purporting 3D Visualization and Volume Estimation of Brain Tumors

This work proposes the Crust algorithm for 3D reconstruction of brain tumor, an effective mechanism in the visualization of tumors for presurgical planning, radiation dose calculation. Despite the promising performance of Crust algorithm in reconstruction of Stanford models, it has not yet been considered in 3D reconstruction of brain tumor. Validation of the results is done using the comparison of the 3D models from two cutting edge techniques namely the Marching Cube and the Alpha shape algorithm. The obtained result shows that Crust algorithm provides the brain tumor model with an average quality of triangle meshes ranging from 0.85 to 0.95. Concerning the visual realism, the quality of Crust algorithm models is higher on comparison to the other models. Precision of tumor volume measurement by convex hull method is analysed by repeatability and reproducibility. The standard deviations of repeatability were between 2.03 % and 3.97 %. The experimental results show that Linear Crust algorithm produces high quality meshes with average quality of equilateral triangles close to 1.

Clinical application of a three-dimensional reconstruction technique for complex liver cancer resection

OBJECTIVE

To explore the utility of three-dimensional (3D) visualization technology in liver resection for patients with complex liver cancer.

METHODS

In this retrospective cohort study, we collected and analyzed clinic pathological data from 105 patients who underwent complicated liver cancer resection at the authors' unit between January 2014 and June 2019. Observation indicators included general demographic information, operative time, intraoperative blood loss, blood transfusion volume, postoperative liver function, complication rate, hospital stay, and in-hospital mortality.

RESULTS

Compared with the complex liver cancer control group, operative time (257.1  ±  63.4 min versus [vs] 326.6  ±  78.3 min; P < 0.001), intraoperative blood loss (256.4  ±  159.1 mL vs 436.1  ±  177.3 mL; P < 0.001), blood transfusion volume (213.3  ±  185.2 mL vs 401.6  ±  211.2 mL; P < 0.001), and length of hospital stay (9.7  ±  3.1 days vs 11.9  ±  3.3 days; P = 0.001) were significantly reduced in the complex liver cancer reconstruction group. Although there was no statistical difference in total postoperative complication rate between the two groups, the incidence of serious postoperative complications in the reconstruction group was significantly lower than that in the control group (3/54 [5.6%] vs 10/51 [19.6%], respectively; P = 0.038). Regarding laboratory investigations, the time to recovery of liver function in the complex liver cancer reconstruction group was shorter than that in the complex liver cancer control group.

CONCLUSION

The use of 3D visualization technology was highly influential in formulating meticulous, individualized surgical strategies for complex liver cancer liver resection with safety and reduced perioperative risk.

Virtual reality and 3D printing improve preoperative visualization of 3D liver reconstructions-results from a preclinical comparison of presentation modalities and user's preference

Background

Preoperative three-dimensional (3D) reconstructions for liver surgery planning have been shown to be effective in reduction of blood loss and operation time. However, the role of the ‘presentation modality’ is not well investigated. We present the first study to compare 3D PDFs, 3D printed models (PR) and virtual reality (VR) 3D models with regard to anatomical orientation and personal preferences in a high volume liver surgery center.

Methods

Thirty participants, 10 medical students, 10 residents, 5 fellows and 5 hepatopancreatobiliary (HPB) experts, assigned the tumor-bearing segments of 20 different patient’s individual liver reconstructions. Liver models were presented in a random order in all modalities. Time needed to specify the tumor location was recorded. In addition, a score was calculated factoring in correct, wrong and missing segment assignments. Furthermore, standardized test/questionnaires for spatial thinking and seeing, vegetative side effects and usability were completed.

Results

Participants named significantly more correct segments in VR (P=0.040) or PR (P=0.036) compared to PDF. Tumor assignment was significantly shorter with 3D PR models compared to 3D PDF (P<0.001) or VR application (P<0.001). Regardless of the modality, HPB experts were significantly faster (24±8 vs. 35±11 sec; P=0.014) and more often correct (0.87±0.12 vs. 0.83±0.15; P<0.001) than medical students. Test results for spatial thinking and seeing had no influence on time but on correctness of tumor assignment. Regarding usability and user experience the VR application achieved the highest scores without causing significant vegetative symptoms and was also the most preferred method (n=22, 73.3%) because of the multiple functions like scaling and change of transparency. Ninety percent (n=27) stated that this application can positively influence the operation planning.

Conclusions

3D PR models and 3D VR models enable a better and partially faster anatomical orientation than reconstructions presented as 3D PDFs. User’s preferred the VR application over the PR models and PDF. A prospective trial is needed to evaluate the different presentation modalities regarding intra- and postoperative outcomes.

Investigating the utility of VR for spatial understanding in surgical planning: evaluation of head-mounted to desktop display

Recent technological advances have made Virtual Reality (VR) attractive in both research and real world applications such as training, rehabilitation, and gaming. Although these other fields benefited from VR technology, it remains unclear whether VR contributes to better spatial understanding and training in the context of surgical planning. In this study, we evaluated the use of VR by comparing the recall of spatial information in two learning conditions: a head-mounted display (HMD) and a desktop screen (DT). Specifically, we explored (a) a scene understanding and then (b) a direction estimation task using two 3D models (i.e., a liver and a pyramid). In the scene understanding task, participants had to navigate the rendered the 3D models by means of rotation, zoom and transparency in order to substantially identify the spatial relationships among its internal objects. In the subsequent direction estimation task, participants had to point at a previously identified target object, i.e., internal sphere, on a materialized 3D-printed version of the model using a tracked pointing tool. Results showed that the learning condition (HMD or DT) did not influence participants' memory and confidence ratings of the models. In contrast, the model type, that is, whether the model to be recalled was a liver or a pyramid significantly affected participants' memory about the internal structure of the model. Furthermore, localizing the internal position of the target sphere was also unaffected by participants' previous experience of the model via HMD or DT. Overall, results provide novel insights on the use of VR in a surgical planning scenario and have paramount implications in medical learning by shedding light on the mental model we make to recall spatial structures.

Three-dimensional visualization technique compared with magnetic resonance cholangiopancreatography for evaluation of anatomic variants of pediatric congenital choledochal cysts

OBJECTIVE

The aim of this study was to compare the application of a three-dimensional (3D) visualization technique and magnetic resonance cholangiopancreatography (MRCP) for diagnosis of pediatric congenital choledochal cysts.

METHODS

Thin slices of coronal heavily T2-weighted pulse sequences of MRI pertaining to 35 patients were retrospectively used to reconstruct 3D models. Diagnoses and variants of the biliary system were evaluated based on the 3D models and MRCP imaging. The quality of delineation of the biliary duct system and the Todani classification were evaluated. Wilcoxon and Chi-squared tests were used for statistical analysis.

RESULTS

Two cases that were diagnosed as type II congenital choledochal cysts using the 3D model were diagnosed as type I using MRCP imaging. Significant differences were observed between the two modalities with respect to the delineation of the right anterior bile duct, right posterior bile duct, and left hepatic duct. The excellent and good rates obtained with the 3D model (65.7%) were much better than that obtained with MRCP (37.1%) imaging. Two cases with accessory hepatic ducts (5.7%), one case with an accessory pancreatic duct (2.8%), and two cases with biliary strictures at the hepatic hilum (5.7%) were detected using the 3D models. In contrast, only one case with an accessory hepatic duct and one case with a biliary stricture at the hepatic hilum were detected using MRCP.

CONCLUSION

The 3D visualization technique facilitated more precise morphological evaluation of congenital choledochal cysts and provided comprehensive spatial anatomic information for diagnosis.

CBCT-based navigation system for open liver surgery: Accurate guidance toward mobile and deformable targets with a semi-rigid organ approximation and electromagnetic tracking of the liver

Purpose

The surgical navigation system that provides guidance throughout the surgery can facilitate safer and more radical liver resections, but such a system should also be able to handle organ motion. This work investigates the accuracy of intraoperative surgical guidance during open liver resection, with a semi‐rigid organ approximation and electromagnetic tracking of the target area.

Methods

The suggested navigation technique incorporates a preoperative 3D liver model based on diagnostic 4D MRI scan, intraoperative contrast‐enhanced CBCT imaging and electromagnetic (EM) tracking of the liver surface, as well as surgical instruments, by means of six degrees‐of‐freedom micro‐EM sensors.

Results

The system was evaluated during surgeries with 35 patients and resulted in an accurate and intuitive real‐time visualization of liver anatomy and tumor's location, confirmed by intraoperative checks on visible anatomical landmarks. Based on accuracy measurements verified by intraoperative CBCT, the system’s average accuracy was 4.0 ± 3.0 mm, while the total surgical delay due to navigation stayed below 20 min.

Conclusions

The electromagnetic navigation system for open liver surgery developed in this work allows for accurate localization of liver lesions and critical anatomical structures surrounding the resection area, even when the liver was manipulated. However, further clinically integrating the method requires shortening the guidance‐related surgical delay, which can be achieved by shifting to faster intraoperative imaging like ultrasound. Our approach is adaptable to navigation on other mobile and deformable organs, and therefore may benefit various clinical applications.

Achieving precision surgery in laparoscopic liver resection with the aid of preoperative three-dimensional reconstruction: A case report

•

Laparoscopic liver surgery is evolving and its spread is now starting to take place.

•

Three-dimensional reconstruction imaging still remains a scarcely used technique.

•

Considering the difficulty of liver resection surgery, a precise knowledge of the patient’s anatomy is essential in the preoperative planning of the intervention. Three-dimensional reconstruction imaging provides useful information in addition to conventional imaging, allowing a more accurate preoperative planning, and being used as a navigation instrument during liver resection.

•

The use of three-dimensional reconstruction imaging allows to predict the precise location and direction of anatomical structures with high approximation, allowing to reach a high degree of precision surgery.

Introduction

The use of three-dimensional image reconstruction in liver surgery is well-known and has got many applications: It was first developed for vein reconstruction in liver transplantation and for liver volumetry to prevent post hepatectomy liver failure (PHLF) after major resections. There are many other advantages described in the literature provided by three-dimensional reconstruction, however its diffusion is currently limited.

Clinical case

We present the case of a woman with a single colon cancer metastasis in segment 5 of the liver. Using CT scan images we created a three dimensional reconstruction of the patient’s liver and its inners structures. The rendering was used to hypothesize the plan of dissection and to predict the pedicles that needed to be dissected during the procedure.

Discussion

We try to demonstrate that, thanks to three dimensional image reconstruction, all the structures that need to be dissected could be effectively located prior to the the surgery with a high grade of approximation. Furthermore the 3D reconstruction could be used as a step by step guide during the whole surgical procedure, showing all the pedicles To be encountered and dissected at every stage.

Conclusion

3d reconstruction of the liver is a valid aid in the interpretation of preoperative imaging and intraoperative ultrasound, both for the surgeon and for the entire equipe, facilitating comprehension of patient’s liver anatomical features. It allows to predict the location and direction of the pedicles that need to be dissected and resected with high approximation, in order to achieve a more precise and tailored surgery.

The Use of a 3D Printing Model in Planning a Donor Hepatectomy for Living Donor Liver Transplantation: First in India

INTRODUCTION

Three-dimensional (3D) anatomical relationships between the hepatic veins and portal structures can serve as a guide to plan resections in donor hepatectomy during living donor liver transplantation. We present the first case report from India on the use of a 3D printed liver model, as an assist to living donor liver transplantation.

METHODS

A 3D model of the donor liver with hepatic venous structures printed within it was prepared using image acquisition data. The model was used for a simulated cut preoperatively, to mimic the donor hepatectomy based on the venous structures seen through the transparent material used for making the liver model. The volume of the graft measured by volume displacement in the actual surgery was compared with the volume of the model after the simulated cut.

RESULTS

The calculated volume of the graft was 359 ml as per the preoperative simulation, and the observed weight/volume was 380 gm/310 ml.

CONCLUSION

Three-dimensional printing of liver models using imaging data can help predict the actual size of the graft after donor hepatectomy, in patients undergoing living donor liver transplantation.

Simulation and navigation liver surgery: an update after 2,000 virtual hepatectomies

The advent of preoperative 3-dimensional (3D) simulation software has made a variety of unprecedented surgical simulations possible. Since 2004, we have performed more than 2,000 preoperative simulations in the University of Tokyo Hospital, and they have enabled us to obtain a great deal of information, such as the detailed shape of liver segments, the precise volume of each segment, and the volume of hepatic venous drainage areas. As a result, we have been able to perform more aggressive and complicated surgery safely. The next step is to create a navigation system that will accurately reproduce the preoperative plan. Real-time virtual sonography (RVS) is a navigation system that provides fusion images of ultrasonography and reconstructed computed tomography images or magnetic resonance images. The RVS system facilitates the surgeon's understanding of interpretation of ultrasound images and the detection of tumors that are difficult to find by ultrasound alone. In the near future, surgical navigation systems may evolve to the point where they will be able to inform surgeons intraoperatively in real time about not only intrahepatic structures, such as vessels and tumors, but also the portal territory, hepatic vein drainage areas, and resection lines that have been planned preoperatively.

Three Dimensional Reconstruction Models for Medical Modalities: A Comprehensive Investigation and Analysis

BACKGROUND

Image reconstruction is the mathematical process which converts the signals obtained from the scanning machine into an image. The reconstructed image plays a fundamental role in the planning of surgery and research in the medical field.

DISCUSSION

This paper introduces the first comprehensive survey of the literature about medical image reconstruction related to diseases, presenting a categorical study about the techniques and analyzing advantages and disadvantages of each technique. The images obtained by various imaging modalities like MRI, CT, CTA, Stereo radiography and Light field microscopy are included. A comparison on the basis of the reconstruction technique, Imaging Modality and Visualization, Disease, Metrics for 3D reconstruction accuracy, Dataset and Execution time, Evaluation of the technique is also performed.

CONCLUSION

The survey makes an assessment of the suitable reconstruction technique for an organ, draws general conclusions and discusses the future directions.

Consensus recommendations of three-dimensional visualization for diagnosis and management of liver diseases

Three-dimensional (3D) visualization involves feature extraction and 3D reconstruction of CT images using a computer processing technology. It is a tool for displaying, describing, and interpreting 3D anatomy and morphological features of organs, thus providing intuitive, stereoscopic, and accurate methods for clinical decision-making. It has played an increasingly significant role in the diagnosis and management of liver diseases. Over the last decade, it has been proven safe and effective to use 3D simulation software for pre-hepatectomy assessment, virtual hepatectomy, and measurement of liver volumes in blood flow areas of the portal vein; meanwhile, the use of 3D models in combination with hydrodynamic analysis has become a novel non-invasive method for diagnosis and detection of portal hypertension. We herein describe the progress of research on 3D visualization, its workflow, current situation, challenges, opportunities, and its capacity to improve clinical decision-making, emphasizing its utility for patients with liver diseases. Current advances in modern imaging technologies have promised a further increase in diagnostic efficacy of liver diseases. For example, complex internal anatomy of the liver and detailed morphological features of liver lesions can be reflected from CT-based 3D models. A meta-analysis reported that the application of 3D visualization technology in the diagnosis and management of primary hepatocellular carcinoma has significant or extremely significant differences over the control group in terms of intraoperative blood loss, postoperative complications, recovery of postoperative liver function, operation time, hospitalization time, and tumor recurrence on short-term follow-up. However, the acquisition of high-quality CT images and the use of these images for 3D visualization processing lack a unified standard, quality control system, and homogeneity, which might hinder the evaluation of application efficacy in different clinical centers, causing enormous inconvenience to clinical practice and scientific research. Therefore, rigorous operating guidelines and quality control systems need to be established for 3D visualization of liver to develop it to become a mature technology. Herein, we provide recommendations for the research on diagnosis and management of 3D visualization in liver diseases to meet this urgent need in this research field.

Assisting Vascular Surgery with Smartphone Augmented Reality

Background Augmented reality is a technology that expands on image-guided surgery to allow intraoperative guidance and navigation. Augmented reality-assisted surgery (ARAS) has not been implemented in the vascular field yet. The wealth of sensors found on modern smartphones make them a promising platform for implementing vascular ARAS. However, current smartphone augmented reality platforms suffer from tracking instability, making them unsuitable for precise surgery. Novel algorithms need to be developed to tackle the stability and performance limitations of mobile phone augmented reality. Aim The primary aim was to develop an ARAS system utilizing low-cost smartphone hardware for vascular surgery. The second aim was to assess its performance by evaluating the stability of its tracking algorithms. Methods We designed an ARAS system utilizing standard optical tracking (SOT) and developed a novel tracking algorithm: hybrid gyroscopic and optical tracking (HGOT) for improved tracking stability. We evaluated the stability of both tracking algorithms using a phantom model and calculated tracking errors using root mean square error (RMSE).  Results The novel augmented reality system displayed a three-dimensional (3D) guidance model fused with the patient's anatomy on a smartphone in real-time. The rotational tracking RMSE was 3.12 degrees for SOT and 0.091 degrees for HGOT. Positional tracking RMSE was 3.3 mm for SOT compared to 0.03 mm for HGOT. Comparing the stability of both tracking techniques showed HGOT to be significantly superior to SOT (p = 0.004). Conclusion We have developed a novel augmented reality system for vascular procedures. The development of HGOT has significantly increased the stability of a low-cost handheld augmented reality solution.

Development of new software enabling automatic identification of the optimal anatomical liver resectable region, incorporating preoperative liver function

Determining the resectable region and volume of the liver prior to anatomical resection is important. The synapse Vincent (SV) system is the current method for surgical liver resection that relies on the surgeon's individual experience and skill. Additionally, in cases involving abnormal liver function, the resectable region is limited due to deteriorating liver function, thus making the determination of the hepatectomy region challenging. The current study outlines a novel 3D Hariyama-Shimoda Soft (HSS) simulation software that can be used to automatically simulate the optimal hepatectomy region under a limited resectable liver volume. The current study recruited patients with hepatic malignant tumors that were scheduled for anatomical resection. The influence of the tumor on each portal vein point was quantified in accordance with the tumor domination ratio (TDR). The resectable region was subsequently determined so that the sum of the TDR was the maximum estimated resectable liver volume (ERLV). The maximum ERLV settings utilized were within Makuuchi's criteria. ERLV was compared with the actual resected liver volume (ARLV) using SV and HSS. A total of 15 patients were included in the present study. The median ERLV was not significantly different between the two groups (P=0.15). However, the correlation between ERLV and ARLV, for SV and HSS, was statistically significant [SV ERLV (ml) = 1.139 × HSS ERLV (ml) + 30.779 (P=0.001)]. In conclusion, HSS may be an effective 3D simulation system. TDR and ERLV were indicated to be novel factors that may be incorporated into simulation software for use in anatomical resection surgery.

How Has Virtual Hepatectomy Changed the Practice of Liver Surgery?: Experience of 1194 Virtual Hepatectomy Before Liver Resection and Living Donor Liver Transplantation

OBJECTIVE

To assess how virtual hepatectomy (VH), conducted using surgical planning software, influences the outcomes of liver surgery.

BACKGROUND

Imaging technology visualizes the territories of the liver vessels, which were previously impossible. However, the clinical impact of VH has not been evaluated.

METHODS

From 2004 to 2013, we performed 1194 VHs preoperatively. Outcomes of living donor liver transplantation (LDLT) and hepatectomy for hepatocellular carcinoma (HCC)/colorectal liver metastases (CRLM) were compared between patients in whom VH was performed (VH) and those without VH evaluation (non-VH).

RESULTS

In LDLT, the rate of right liver graft use was higher in the VH (62.1%) than in the non-VH (46.5%) (P < 0.01), which did not increase morbidity of donor surgery. Duration of recipient surgery in the VH in which middle hepatic vein branch reconstruction was skipped was shorter than that in the VH with venous reconstruction. Among HCC patients with impaired liver function, portal territory-oriented resection was conducted more often in the VH than in the non-VH. The 5-year disease-free survival rate for localized HCC was higher in the VH than in the non-VH (37.2% vs 23.9%; P = 0.04). In CRLM, long-term outcomes were similar in the VH and non-VH despite the larger tumor load in the VH.

CONCLUSIONS

VH in LDLT allows double equipoise for the recipient and donor by optimizing decision-making on graft selection and venous reconstruction. VH offers a chance for radical hepatectomy even in HCC patients with impaired liver function and CRLM patients with advanced tumors, without compromising survival.

Application of 3-Dimensional Printing in Pediatric Living Donor Liver Transplantation: A Single-Center Experience

Three-dimensional (3D) printing has been used to support organ transplantations. However, whether it helps remains unclear. This study aimed to present and assess the application of 3D-printed liver models in pediatric living donor liver transplantation (LDLT). The 3D images were printed to touchable liver models with transparent liver parenchyma, specifically colored hepatic vessels, and biliary structures. A total of 30 consecutive recipients were enrolled in the study: 10 were operated on with the support of 3D printing (3D-printing group) and 20 (control group) were operated on without it. Detailed photographs and data of the cases in the 3D-printing group were presented. One patient underwent auxiliary partial orthotopic liver transplantation using the left lobe graft, in which the abdominal cavity model was also printed to test whether the planned graft fit the recipient's abdominal cavity. The 3D-printed models facilitated surgical planning and procedures, particularly in the management of hepatic veins and in the prevention of large-for-size syndrome. The operative time of donors in the 3D-printing group was significantly shorter compared with the control group (2.3 ± 0.4 versus 3.0 ± 0.4 hours; P < 0.001). Inpatient costs for donors in the 3D-printing group were 17.1% lower than those in the control group (34.6 ± 6.6 versus 41.7 ± 10.4 thousand ¥; P = 0.03). In conclusion, in small infants and complicated pediatric LDLT patients, 3D-printed models can help minimize the risk of large-for-size syndrome and graft reduction. The 3D-printed models may be conducive to liver graft procurement and intraoperative assistance in pediatric LDLT.

Digital and intelligent liver surgery in the new era: Prospects and dilemmas

Despite tremendous advances in traditional imaging technology over the past few decades, the intraoperative identification of lesions is still based on naked eye observation or pre-operative image evaluation. However, these two-dimensional image data cannot objectively reflect the complex anatomical structure of the liver and the detailed morphological features of the lesion, which directly limits the clinical application value of these imaging data in surgery in that it cannot improve the curative efficacy of surgery and the prognosis of the patient. This traditional mode of diagnosis and treatment has been changed by digital medical imaging technology in the new era with its significant function of accurate and efficient diagnosis of diseases, selection of reasonable treatment schemes, improvement of radical resection rate and reduction of surgical risk. In this paper, we reviewed the latest application of digital intelligent diagnosis and treatment technology related to liver surgery in the hope that it may help to achieve accurate treatment of liver surgery diseases.

Should We Have Blind Faith in Liver Volumetry?

Introduction: Liver volumetry is a routine procedure performed before major hepatectomy or living donor liver transplantation (LDLT) to anticipate the remnant liver volume and prevent liver failure. However, many parameters may impact its accuracy and no large-scale studies have evaluated inter-rater variabilities. We aimed to determine the reliability of volumetric assessments for whole organs in deceased-donor liver transplantations (DDLT) and partial organs in LDLT settings. Patients & Methods: Eight operators (four surgeons + four radiologists) analysed 30 preoperative CT scans (15 whole cirrhotic livers in the DDLT group + 15 partial healthy grafts in the LDLT group), using five software systems. The computed volumes were compared with liver weight; liver density being considered as1. Results: Inter-rater and inter-software concordances were excellent with coefficients of correlation >0.9. However, calculations overestimated the real volumes in 25 cases by a mean of 249 ± 206 [14-771] cc in the DDLT group and 138 ± 92cc [39-375] in the LDLT group. The mean calculations were significantly higher than liver weights in the LDLT group only (p=0.04). The radiologists overestimated the surgeons’ assessment in 24 cases, the differences exceeding 6% in some cases. The type of software used significantly impacted results in the DDLTgroup. Conclusions: Despite its unanimously recognised utility, we highlight significant discrepancies between estimated and real liver volumes. The global overestimation may lead to leave of too small remnant liver, with potentially dramatic consequences. In case of border-line estimations, we recommend a repetition of the evaluation by another operator (surgeon + radiologist working in concert).

Practical Contribution of Virtual Hepatectomy for Colorectal Liver Metastases: a Propensity-Matched Analysis of Clinical Outcome

BACKGROUND

Recent improvements in imaging technologies have enabled surgeons to perform precise planning using virtual hepatectomy (VH). However, the practical and clinical benefits of VH remain unclear. This study sought to assess how three-dimensional analysis using a VH contributed to preoperative planning and postoperative outcome in patients undergoing liver surgery for the treatment of colorectal liver metastases (CRLM).

METHODS

From 2007 to 2017, a total of 473 CRLM patients who received curative hepatectomy were retrospectively assessed. A 1:1 matched propensity analysis was performed between patients who did not receive a VH (without 3D group: n = 188) and received a VH (3D(+) group: n = 285).

RESULT

The rate of VH increased over the study period (P < 0.001). After propensity score matching (n = 150 for each group), no significant differences were observed in the intraoperative and postoperative outcome, including liver transection time, blood loss, or morbidity between the groups. More patients received a small anatomical resection (plus limited resections) in the 3D(+) group (25 vs 11%, [P = 0.03]). A submillimeter margin was less frequent in the 3D(+) group. No significant differences in the 5-year overall survival and disease-free survival rates were seen between the without 3D group and the 3D(+) group (38.0 vs. 45.9% [P = 0.99], 11.1 vs. 21.7%, respectively [P = 0.109]).

CONCLUSION

Although VH did not significantly influenced on the long-term outcome after hepatectomy, a more parenchymal-sparing operative procedure (anatomical resections, plus limited resections) was selected and the risk of a submillimeter surgical margin was reduced after introduction of VH.

Impact of 3D printing technology on the comprehension of surgical liver anatomy

BACKGROUND AND AIMS

Surgical planning in liver resection depends on the precise understanding of the three-dimensional (3D) relation of tumors to the intrahepatic vascular trees. This study aimed to investigate the impact of 3D printing (3DP) technology on the understanding of surgical liver anatomy.

METHODS

We selected four hepatic tumors that were previously resected. For each tumor, a virtual 3D reconstruction (VIR) model was created from multi-detector computed tomography (MDCT) and was prototyped using a 3D printer. Forty-five surgical residents were evenly assigned to each group (3DP, VIR, and MDCT groups). After evaluation of the MDCT scans, VIR model, or 3DP model of each tumor, surgical residents were asked to assign hepatic tumor locations and state surgical resection proposals. The time used to specify the tumor location was recorded. The correct responses and time spent were compared between the three groups.

RESULTS

The assignment of tumor location improved steadily from MDCT, to VIR, and to 3DP, with a mean score of 34.50, 55.25, and 80.92, respectively. These scores were out of 100 points. The 3DP group had significantly higher scores compared with other groups (p < 0.001). Furthermore, 3DP significantly improved the accuracy of surgical resection proposal (p < 0.001). The mean accuracy of the surgical resection proposal for 3DP, VIR, and MDCT was 57, 25, and 25%, respectively. The 3DP group took significantly less time, compared with other groups (p < 0.005). The mean time spent on assessing the tumor location for 3DP, VIR, and MDCT groups was 93, 223, and 286 s, respectively.

CONCLUSIONS

3D printing improves the understanding of surgical liver anatomy for surgical residents. The improved comprehension of liver anatomy may facilitate laparoscopy or open liver resection.

Virtual Reality Exploration and Planning for Precision Colorectal Surgery

BACKGROUND

Medical software can build a digital clone of the patient with 3-dimensional reconstruction of Digital Imaging and Communication in Medicine images. The virtual clone can be manipulated (rotations, zooms, etc), and the various organs can be selectively displayed or hidden to facilitate a virtual reality preoperative surgical exploration and planning.

OBJECTIVE

We present preliminary cases showing the potential interest of virtual reality in colorectal surgery for both cases of diverticular disease and colonic neoplasms.

DESIGN

This was a single-center feasibility study.

SETTINGS

The study was conducted at a tertiary care institution.

PATIENTS

Two patients underwent a laparoscopic left hemicolectomy for diverticular disease, and 1 patient underwent a laparoscopic right hemicolectomy for cancer. The 3-dimensional virtual models were obtained from preoperative CT scans. The virtual model was used to perform preoperative exploration and planning. Intraoperatively, one of the surgeons was manipulating the virtual reality model, using the touch screen of a tablet, which was interactively displayed to the surgical team.

MAIN OUTCOME MEASURES

The main outcome was evaluation of the precision of virtual reality in colorectal surgery planning and exploration.

RESULTS

In 1 patient undergoing laparoscopic left hemicolectomy, an abnormal origin of the left colic artery beginning as an extremely short common trunk from the inferior mesenteric artery was clearly seen in the virtual reality model. This finding was missed by the radiologist on CT scan. The precise identification of this vascular variant granted a safe and adequate surgery. In the remaining cases, the virtual reality model helped to precisely estimate the vascular anatomy, providing key landmarks for a safer dissection.

LIMITATIONS

A larger sample size would be necessary to definitively assess the efficacy of virtual reality in colorectal surgery.

CONCLUSIONS

Virtual reality can provide an enhanced understanding of crucial anatomical details, both preoperatively and intraoperatively, which could contribute to improve safety in colorectal surgery.

Utility of 3D Reconstruction of 2D Liver Computed Tomography/Magnetic Resonance Images as a Surgical Planning Tool for Residents in Liver Resection Surgery

OBJECTIVE

A fundamental aspect of surgical planning in liver resections is the identification of key vessel tributaries to preserve healthy liver tissue while fully resecting the tumor(s). Current surgical planning relies primarily on the surgeon's ability to mentally reconstruct 2D computed tomography/magnetic resonance (CT/MR) images into 3D and plan resection margins. This creates significant cognitive load, especially for trainees, as it relies on image interpretation, anatomical and surgical knowledge, experience, and spatial sense. The purpose of this study is to determine if 3D reconstruction of preoperative CT/MR images will assist resident-level trainees in making appropriate operative plans for liver resection surgery.

DESIGN

Ten preoperative patient CT/MR images were selected. Images were case-matched, 5 to 2D planning and 5 to 3D planning. Images from the 3D group were segmented to create interactive digital models that the resident can manipulate to view the tumor(s) in relation to landmark hepatic structures. Residents were asked to evaluate the images and devise a surgical resection plan for each image. The resident alternated between 2D and 3D planning, in a randomly generated order. The primary outcome was the accuracy of resident's plan compared to expert opinion. Time to devise each surgical plan was the secondary outcome. Residents completed a prestudy and poststudy questionnaire regarding their experience with liver surgery and the 3D planning software.

SETTING AND PARTICIPANTS

Senior level surgical residents from the Queen's University General Surgery residency program were recruited to participate.

RESULTS

A total of 14 residents participated in the study. The median correct response rate was 2 of 5 (40%; range: 0-4) for the 2D group, and 3 of 5 (60%; range: 1-5) for the 3D group (p < 0.01). The average time to complete each plan was 156 ± 107 seconds for the 2D group, and 84 ± 73 seconds for the 3D group (p < 0.01). A total 13 of 14 residents found the 3D model easier to use than the 2D. Most residents noticed a difference between the 2 modalities and found that the 3D model improved their confidence with the surgical plan proposed.

CONCLUSIONS

The results of this study show that 3D reconstruction for liver surgery planning increases accuracy of resident surgical planning and decreases amount of time required. 3D reconstruction would be a useful model for improving trainee understanding of liver anatomy and surgical resection, and would serve as an adjunct to current 2D planning methods. This has the potential to be developed into a module for teaching liver surgery in a competency-based medical curriculum.

Comprehensive evaluation of liver resection procedures: surgical mind development through cognitive task analysis

Background

Liver resection is a complex procedure for trainee surgeons. Cognitive task analysis (CTA) facilitates understanding and decomposing tasks that require a great proportion of mental activity from experts.

Methods

Using CTA and video-based coaching to compare liver resection by open and laparoscopic approaches, we decomposed the task of liver resection into exposure (visual field building), adequate tension made at the working plane (which may change three-dimensionally during the resection process), and target processing (intervention strategy) that can bridge the gap from the basic surgical principle.

Results

The key steps of highly-specialized techniques, including hanging maneuvers and looping of extra-hepatic hepatic veins, were shown on video by open and laparoscopic approaches.

Conclusions

Familiarization with laparoscopic anatomical orientation may help surgeons already skilled at open liver resection transit to perform laparoscopic liver resection smoothly. Facilities at hand (such as patient tolerability, advanced instruments, and trained teams of personnel) can influence surgical decision making. Application of the rationale and realizing the interplay between the surgical principles and the other paramedical factors may help surgeons in training to understand the mental abstractions of experienced surgeons, to choose the most appropriate surgical strategy effectively at will, and to minimize the gap.

Assessment and optimization of liver volume before major hepatic resection: Current guidelines and a narrative review

Post hepatectomy liver failure (PHLF) remains a significant cause of morbidity and mortality after major liver resection. Although the etiology of PHLF is multifactorial, an inadequate functional liver remnant (FLR) is felt to be the most important modifiable predictor of PHLF. Pre-operative evaluation of FLR function and volume is of paramount importance before proceeding with any major liver resection. Patients with inadequate or borderline FLR volume must be considered for volume optimization strategies such as portal vein embolization (PVE), two stage hepatectomy with portal vein ligation (PVL), Yttrium-90 radioembolization, and associating liver partition and portal vein ligation for staged hepatectomy (ALPPS). This paper provides an overview of assessing FLR volume and function, and discusses indications and outcomes of commonly used volume optimization strategies.

The Effect of Three-Dimensional Preoperative Simulation on Liver Surgery

Background

In the past decade, three-dimensional (3D) simulation has been commonly used for liver surgery. However, few studies have analyzed the usefulness of this 3D simulation. The aim of this study was to evaluate the effect of 3D simulation on the outcome of liver surgery.

Methods

We retrospectively analyzed 240 consecutive patients who underwent liver resection. The patients were divided into two groups: those who received 3D preoperative simulation (“3D group”, n = 120) and those who did not undergo 3D preoperative simulation (“without 3D group”, n = 120). The perioperative outcomes, including operation time, blood loss, maximum aspartate transaminase level, length of postoperative stay, postoperative complications and postoperative mortality, were compared between the two groups. The predicted resected liver volume was compared with the actual resected volume.

Results

The median operation time for the 3D group was 36 min shorter than that for the without 3D group (P = 0.048). There were no significant differences in other outcomes between the two groups. A subgroup analysis revealed that the operation time of repeated hepatectomy and segmentectomy for the 3D group was shorter than that for the without 3D group (P = 0.03). There was a strong correlation between the predicted liver volume and the actual resected liver weight (r = 0.80, P < 0.001).

Conclusion

These findings demonstrate that 3D preoperative simulation may reduce the operation time, particularly for repeated hepatectomy and segmentectomy.

A novel method for planning liver resections using deformable Bézier surfaces and distance maps

BACKGROUND AND OBJECTIVE

For more than a decade, computer-assisted surgical systems have been helping surgeons to plan liver resections. The most widespread strategies to plan liver resections are: drawing traces in individual 2D slices, and using a 3D deformable plane. In this work, we propose a novel method which requires low level of user interaction while keeping high flexibility to specify resections.

METHODS

Our method is based on the use of Bézier surfaces, which can be deformed using a grid of control points, and distance maps as a base to compute and visualize resection margins (indicators of safety) in real-time. Projection of resections in 2D slices, as well as computation of resection volume statistics are also detailed.

RESULTS

The method was evaluated and compared with state-of-the-art methods by a group of surgeons (n=5, 5-31 years of experience). Our results show that theproposed method presents planning times as low as state-of-the-art methods (174 s median time) with high reproducibility of results in terms of resected volume. In addition, our method not only leads to smooth virtual resections easier to perform surgically compared to other state-of-the-art methods, but also shows superior preservation of resection margins.

CONCLUSIONS

Our method provides clinicians with a robust and easy-to-use method for planning liver resections with high reproducibility, smoothness of resection and preservation of resection margin. Our results indicate the ability of the method to represent any type of resection and being integrated in real clinical work-flows.

Novel imaging using a touchless display for computer-assisted hepato-biliary surgery

PURPOSE

We developed a touchless display system that allows the user to control the medical imaging software via hand gestures in the air. We conducted this study to verify the effectiveness of this novel touchless display system as a tool for assisting with surgical imaging.

METHODS

The patient's computed tomography (CT) data are generally observed on a display during surgery. The "Dr. aeroTAP" touchless display system was developed to generate virtual mouse events based on the position of one hand. We conducted comparative analyses of using the Dr. aeroTAP vs. using a regular mouse (control group) by measuring the time to select a 3D image from 24 thumbnail images on a screen (study 1) and to then see the CT image on the DICOM viewer (study 2).

RESULTS

We used the Dr. aeroTAP in 31 hepato-biliary operative procedures performed at our hospital. In study 1, which measured the time required to select one of 24 thumbnails, there were significant differences between the mouse and Dr. aeroTAP groups for all five surgeons who participated (P < 0.001). In study 2, there were also significant differences in the time required for CT DICOM images to be displayed (P < 0.001).

CONCLUSIONS

The touchless interface proved efficient for allowing the observation of surgical images while maintaining a sterile field during surgery.

Three-Dimensional Liver Surgery Simulation: Computer-Assisted Surgical Planning with Three-Dimensional Simulation Software and Three-Dimensional Printing<sup/>

To perform accurate hepatectomy without injury, it is necessary to understand the anatomical relationship among the branches of Glisson's sheath, hepatic veins, and tumor. In Japan, three-dimensional (3D) preoperative simulation for liver surgery is becoming increasingly common, and liver 3D modeling and 3D hepatectomy simulation by 3D analysis software for liver surgery have been covered by universal healthcare insurance since 2012. Herein, we review the history of virtual hepatectomy using computer-assisted surgery (CAS) and our research to date, and we discuss the future prospects of CAS. We have used the SYNAPSE VINCENT medical imaging system (Fujifilm Medical, Tokyo, Japan) for 3D visualization and virtual resection of the liver since 2010. We developed a novel fusion imaging technique combining 3D computed tomography (CT) with magnetic resonance imaging (MRI). The fusion image enables us to easily visualize anatomic relationships among the hepatic arteries, portal veins, bile duct, and tumor in the hepatic hilum. In 2013, we developed an original software, called Liversim, which enables real-time deformation of the liver using physical simulation, and a randomized control trial has recently been conducted to evaluate the use of Liversim and SYNAPSE VINCENT for preoperative simulation and planning. Furthermore, we developed a novel hollow 3D-printed liver model whose surface is covered with frames. This model is useful for safe liver resection, has better visibility, and the production cost is reduced to one-third of a previous model. Preoperative simulation and navigation with CAS in liver resection are expected to help planning and conducting a surgery and surgical education. Thus, a novel CAS system will contribute to not only the performance of reliable hepatectomy but also to surgical education.

Postoperative liver volume was accurately predicted by a medical image three dimensional visualization system in hepatectomy for liver cancer

BACKGROUND

Liver cancer is the second most common cause of cancer death worldwide. The hepatectomy is the most effective and the only potentially curative treatment for patients with resectable neoplasm. Precisely preoperative assessment of remnant liver volume is essential in preventing postoperative liver failure. The aim of our study is to report our experience of using a medical image three dimensional (3D) visualization system (MI-3DVS), which was developed by our team, in assisting hepatectomy for patients with liver cancer.

METHODS

Between January 2010 and June 2016, 69 patients with liver cancer underwent hepatic resection based on the MI-3DVS were enrolled in this study. All patients underwent CT scan 5 days before the surgery and within 5 days after resection. CT images were reconstructed with the MI-3DVS to assist to perform hepatectomy. Simple linear regression, intra-class correlation coefficient (ICC) and Bland-Altman analysis were used to evaluate the relationship and agreement between actual excisional liver volume (AELV) and predicted excisional liver volume (PELV).

RESULTS

Among 69 patients in this study, 62(89.85%) of them were diagnosed with hepatocellular carcinoma by histopathologic examination, and 41(59.42%) underwent major hepatectomy. The average AELV was 330.13 cm³ and the average PELV was 287.67 cm³. The simple regression equation is AELV = 1.016 × PELV+30.39(r = 0.966; p < 0.0003). PELV (ICC = 0.964) achieved an excellent agreement with AELV with statistical significance (p < 0.001). 65 of 69 dots are in the range of 95% confidence interval in Bland-Altman analyses.

CONCLUSIONS

The MI-3DVS has advantages of simple usage and convenient hold. It is accurate in assessment of postoperative liver volume and improve safety in liver resection.

Body Mass Index and Stump Morphology Predict an Increased Incidence of Pancreatic Fistula After Pancreaticoduodenectomy

BACKGROUND

A majority of factors associated with the occurrence of clinical relevant postoperative pancreatic fistula (CR-POPF) after pancreaticoduodenectomy (PD) can only be identified intra- or postoperatively. There are no reports for assessing the morphological features of pancreatic stump and analyzing its influence on CR-POPF risk after PD preoperatively.

METHOD

A total of 90 patients underwent PD between April 2012 and May 2014 in our hospital were included. Preoperative computed tomographic (CT) images were imported into the Medical Image Three-Dimensional Visualization System (MI-3DVS) for acquiring the morphological features of pancreatic stump. The demographics, laboratory test and morphological features of pancreatic stump were recorded prospectively. The clinical course was evaluated focusing on the occurrence of pancreatic fistula as defined by the International Study Group on Pancreatic Fistula (ISGPF). Logistic regression analysis was used to identify independent predictors of CR-POPF.

RESULTS

CR-POPF occurred in 18 patients (14 grade B, 4 grade C). In univariate analysis, male gender (P = 0.026), body mass index (BMI) ≥ 25.3 kg/m(2) (P = 0.002), main pancreas duct diameter (MPDD) < 3.1 mm (P = 0.005), remnant pancreatic parenchymal volume (RPPV) > 27.8 mL (P < 0.001), and area of cut surface (AOCS) > 222.3 mm(2) (P < 0.001) were associated with an increased risk of CR-POPF. In multivariate analysis, BMI ≥ 25.3 kg/m(2) (OR 12.238, 95 % CI 1.822-82.215, P = 0.010) and RPPV > 27.8 mL (OR 12.907, 95 % CI 1.602-104.004, P = 0.016) were the only independent risk factors associated with CR-POPF. A cut-off value of 27.8 mL for RPPV established based on the receiver operating characteristic (ROC) curve, which was the strongest single predictive factor for CR-POPF, with a sensitivity and specificity of 77.8 and 86.1 %, respectively. The area under the ROC curve of RPPV was 0.770 (95 % CI 0.629-0.911, P < 0.001).

CONCLUSIONS

Our study demonstrated that CR-POPF is correlated with BMI and RRPV. MI-3DVS provides us a novel and convenient method for measuring the RPPV. Preoperative acquisition of RPPV and BMI may help the surgeons in fitting postoperative management to patient's individual risk after PD.

Liver Segmentation on CT and MR Using Laplacian Mesh Optimization

OBJECTIVE

The purpose of this paper is to describe a semiautomated segmentation method for the liver and evaluate its performance on CT-scan and MR images.

METHODS

First, an approximate 3-D model of the liver is initialized from a few user-generated contours to globally outline the liver shape. The model is then automatically deformed by a Laplacian mesh optimization scheme until it precisely delineates the patient's liver. A correction tool was implemented to allow the user to improve the segmentation until satisfaction.

RESULTS

The proposed method was tested against 30 CT-scans from the SLIVER07 challenge repository and 20 MR studies from the Montreal University Hospital Center, covering a wide spectrum of liver morphologies and pathologies. The average volumetric overlap error was 5.1% for CT and 7.6% for MRI and the average segmentation time was 6 min.

CONCLUSION

The obtained results show that the proposed method is efficient, reliable, and could effectively be used routinely in the clinical setting.

SIGNIFICANCE

The proposed approach can alleviate the cumbersome and tedious process of slice-wise segmentation required for precise hepatic volumetry, virtual surgery, and treatment planning.

Usefulness of three-dimensional(3D) simulation software in hepatectomy for pediatric hepatoblastoma

BACKGROUND

Hepatoblastoma (HB) is the most common malignant liver tumor in childhood. Complete HB surgical resection which is technically demanding is the cornerstone of effective therapy with a good prognosis. The aim of our study is to evaluate the usefulness of 3D simulation software in assisting hepatectomy in pediatric patients with HB.

METHODS

21 children with HB who underwent hepatectomy were enrolled in this study. All patients underwent computer tomography (CT) imaging preoperatively. CT images from 11 cases (from September 2013 to August 2015) were reconstructed with Hisense CAS, and performed hetpatectomy. While 10 cases (from September 2011 to August 2013) without 3D simulation were token as the control group. The clinical outcome were analyzed and compared between the 2 groups.

RESULTS

All the HB were successfully removed for all patients and there was no positive margins in the surgical specimens, no complications, and no recurrences. For the reconstructing group, 3D simulation software successfully reconstructed the 3D images of liver and were used as a navigator in the operation room during hepatectomy. Anatomic hepatectomy were successfully completed for all patients after operation planning using the software. There was no obvious discrepancy between the virtual and the actual hepatectomy. The mean operation time was shorter (142.18 ± 21.87 min VS. the control group, 173.5 ± 54.88 min, p = 0.047) and intraoperative bleeding was less (28.73 ± 14.17 ml VS. 42.8 ± 41.12 ml, p = 0.011) in the reconstructing group. Moreover, postoperative hospital stay tended to be shorter in the reconstructing group (11.18 ± 2.78d VS. the control group 13 ± 3.46d, P = 0.257).

CONCLUSIONS

3D simulation software facilitates the investigation of the complex liver structure, contributes to the optimal operation planning, and enables an individualized anatomic hepatectomy for each pediatric patient with HB.

[Importance of preoperative and intraoperative imaging for operative strategies]

Recent advances in preoperative and postoperative imaging have an increasing influence on surgical decision-making and make more complex surgical interventions possible. This improves the possibilities for frequently occurring challenges and promoting improved functional and oncological outcome. This manuscript reviews the role of preoperative and intraoperative imaging in surgery. Various techniques are explained based on examples from hepatobiliary surgery and neurosurgery, in particular real-time procedures, such as the online use of augmented reality and in vivo fluorescence, as well as new and promising optical techniques including imaging of intrinsic signals and vibrational spectroscopy.