The effects of real-time image navigation in operative liver surgery

Liver Phantoms Cast in 3D-Printed Mold for Image-Guided Procedures

INTRODUCTION

Image-guided invasive procedures on the liver require a steep learning curve to acquire the necessary skills. The best and safest way to achieve these skills is through hands-on courses that include simulations and phantoms of different complications, without any risks for patients. There are many liver phantoms on the market made of various materials; however, there are few multimodal liver phantoms, and only two are cast in a 3D-printed mold.

METHODS

We created a virtual liver and 3D-printed mold by segmenting a CT scan. The InVesalius and Autodesk Fusion 360 software packages were used for segmentation and 3D modeling. Using this modular mold, we cast and tested silicone- and gelatin-based liver phantoms with tumor and vascular formations inside. We tested the gelatin liver phantoms for several procedures, including ultrasound diagnosis, elastography, fibroscan, ultrasound-guided biopsy, ultrasound-guided drainage, ultrasound-guided radio-frequency ablation, CT scan diagnosis, CT-ultrasound fusion, CT-guided biopsy, and MRI diagnosis. The phantoms were also used in hands-on ultrasound courses at four international congresses.

RESULTS

We evaluated the feedback of 33 doctors regarding their experiences in using and learning on liver phantoms to validate our model for training in ultrasound procedures.

CONCLUSIONS

We validated our liver phantom solution, demonstrating its positive impact on the education of young doctors who can safely learn new procedures thus improving the outcomes of patients with different liver pathologies.

Gelatin-Based Liver Phantoms for Training Purposes: A Cookbook Approach

Background: Patients with liver pathology benefit from image-guided interventions. Training for interventional procedures is recommended to be performed on liver phantoms until a basic proficiency is reached. In the last 40 years, several attempts have been made to develop materials to mimic the imaging characteristics of the human liver in order to create liver phantoms. There is still a lack of accessible, reproducible and cost-effective soft liver phantoms for image-guided procedure training. Methods: Starting from a CT-scan DICOM file, we created a 3D-printed liver mold using InVesalius (Centro de Tecnologia da informação Renato Archer CTI, InVesalius 3 open-source software, Campinas, Brazil) for segmentation, Autodesk Fusion 360 with Netfabb (Autodesk software company, Fusion 360 2.0.19426 with Autodesk Netfabb Premium 2023.0 64-Bit Edition, San Francisco, CA, USA) for 3D modeling and Stratasys Fortus 380 mc 3D printer (Stratasys 3D printing company, Fortus 380 mc 3D printer, Minneapolis, MN, USA). Using the 3D-printed mold, we created 14 gelatin-based liver phantoms with 14 different recipes, using water, cast sugar and dehydrated gelatin, 32% fat bovine milk cream with intravenous lipid solution and technical alcohol in different amounts. We tested all these phantoms as well as ex vivo pig liver and human normal, fatty and cirrhotic liver by measuring the elasticity, shear wave speed, ultrasound attenuation, CT-scan density, MRI signal intensity and fracture force. We assessed the results of the testing performed, as well as the optical appearance on ultrasound, CT and MRI, in order to find the best recipe for gelatin-based phantoms for image-guided procedure training. Results: After the assessment of all phantom recipes, we selected as the best recipe for transparent phantoms one with 14 g of gelatin/100 mL water and for opaque phantom, the recipes with 25% cream. Conclusions: These liver gelatin-based phantom recipes are an inexpensive, reproducible and accessible alternative for training in image-guided and diagnostic procedures and will meet most requirements for valuable training.

Dynamic Hepatocellular Carcinoma Model Within a Liver Phantom for Multimodality Imaging

Introduction

Hepatocellular carcinoma (HCC) is one of the most common cancer in the world, and the effectiveness of its treatment lies in its detection in its early stages. The aim of this study is to mimic HCC dynamically through a liver phantom and apply it in multimodality medical imaging techniques including magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound.

Methods and materials

The phantom is fabricated with two main parts, liver parenchyma and HCC inserts. The liver parenchyma was fabricated by adding 2.5 wt% of agarose powder combined with 2.6 wt% of wax powder while the basic material for the HCC samples was made from polyurethane solution combined with 5 wt% glycerol. Three HCC samples were inserted into the parenchyma by using three cylinders implanted inside the liver parenchyma. An automatic injector is attached to the input side of the cylinders and a suction device connected to the output side of the cylinders. After the phantom was prepared, the contrast materials were injected into the phantom and imaged using MRI, CT, and ultrasound.

Results

Both HCC samples and liver parenchyma were clearly distinguished using the three imaging modalities: MRI, CT, and ultrasound. Doppler ultrasound was also applied through the HCC samples and the flow pattern was observed through the samples.

Conclusion

A multimodal dynamic liver phantom, with HCC tumor models have been fabricated. This phantom helps to improve and develop different methods for detecting HCC in its early stages.

Anthropomorphic liver phantom with flow for multimodal image-guided liver therapy research and training

Purpose

The objective of this study was to develop a multimodal, permanent liver phantom displaying functional vasculature and common pathologies, for teaching, training and equipment development in laparoscopic ultrasound and navigation.

Methods

Molten wax was injected simultaneously into the portal and hepatic veins of a human liver. Upon solidification of the wax, the surrounding liver tissue was dissolved, leaving a cast of the vessels. A connection was established between the two vascular trees by manually manipulating the wax. The cast was placed, along with different multimodal tumor models, in a liver shaped mold, which was subsequently filled with a polymer. After curing, the wax was melted and flushed out of the model, thereby establishing a system of interconnected channels, replicating the major vasculature of the original liver. Thus, a liquid can be circulated through the model in a way that closely mimics the natural blood flow.

Results

Both the tumor models, i.e., the metastatic tumors, hepatocellular carcinoma and benign cyst, and the vessels inside the liver model, were clearly visualized by all the three imaging modalities: CT, MR and ultrasound. Doppler ultrasound images of the vessels proved the blood flow functionality of the phantom.

Conclusion

By a two-step casting procedure, we produced a multimodal liver phantom, with open vascular channels, and tumor models, that is the next best thing to practicing imaging and guidance procedures in animals or humans. The technique is in principle applicable to any organ of the body.

CT findings and features of postoperative abdominal infection patients with pancreatic carcinoma

Objective:

To investigate the values of Computed Tomography (CT) in diagnosing postoperative pancreatic surgeryabdominalinfection and its efficacy and to provide a reasonable method for the diagnosis of abdominal infection.

Methods:

Seventy-two patients who were confirmed as resectablepancreatic carcinoma by physical examination, CT, positron emission tomography (PET)/CT, endoscopic retrograde cholangiopancreatography (ER-CP), endoscopic ultrasonography and mesenteric angiography and were admitted to the Binzhou People’s Hospital, Shandong, China, from July 2013 to July 2015 were randomly selected. The plain CT images and clinical data of the patients were retrospectively analyzed.

Results:

Among 72 patients, 32 patients were diagnosed as abdominal infection by CT, three patients were misdiagnosed (two cases of intestinal obstruction and one case of intraperitoneal abscess), and 2 patients were wrongly diagnosed as suppurative abdominal inflammation. As regards distribution of CT imaging positive performance, the number of patients with intestinal loop abscess accounted for 41.7%, subphrenic abscess for 16.7%, pelvic abscess for 33.3%, the existence of septation for 25%, and emphysema sign for 16.7%. As to the distribution of CT findings of intestinal obstruction, 46.1% of patients had dilatation of intestine, 30.8% for bowel wall thickening, 7.7% had abnormal enhancement, 11.1% had density abnormality, and 15.4% had mesenteric effusion. CT features of purulent peritonitis showed 57.1% of patients had peritoneal thickening, 42.9% had peritoneal effusion, 42.9% had free intraperitoneal air, 14.3% had intestinal walls edema, and 28.6% had mesenteric edema.

Conclusion:

The diagnosis of postoperative abdominal infection of patients with pancreatic carcinoma using CT is quick and efficient showing the pattern and distribution of collection and the gross reaction to the exciting infection.

Multimodal phantom of liver tissue

Medical imaging plays an important role in patients' care and is continuously being used in managing health and disease. To obtain the maximum benefit from this rapidly developing technology, further research is needed. Ideally, this research should be done in a patient-safe and environment-friendly manner; for example, on phantoms. The goal of this work was to develop a protocol and manufacture a multimodal liver phantom that is suitable for ultrasound, computed tomography, and magnetic resonance imaging modalities. The proposed phantom consists of three types of mimicked soft tissues: liver parenchyma, tumors, and portal veins, that are made of six ingredients: candle gel, sephadex®, agarose, glycerol, distilled water, and silicone string. The entire procedure is advantageous, since preparation of the phantom is simple, rather cost-effective, and reasonably quick – it takes around 2 days. Besides, most of the phantom's parts can be reused to manufacture a new phantom. Comparison of ultrasound images of real patient's liver and the developed phantom shows that the phantom's liver tissue and its structures are well simulated.

Evaluation of a resectable ultrasound liver phantom for testing of surgical navigation systems

A formerly developed ultrasound liver phantom for testing of surgical navigation systems and liver resection trainings was evaluated experimentally. The phantom was scanned with CT and the dataset was analyzed with existing segmentation techniques. A virtual 3D model was generated on the basis of the segmentation; it was later used for phantom registration in a surgical assistance navigation system. Within an experiment, ten test persons have tried to touch three tumor models hidden in the phantom with the tip of a resection instrument. In 67% of overall 30 touch trials it was a successful touch at the first go. It means that the developed liver phantom is appropriate for testing of surgical navigation systems, as well as for computer assisted liver resection trainings.

Nerve block using a navigation system and ultrasound imaging for regional anesthesia

During the last few years, regional anesthesia using ultrasound imaging has increased dramatically in both clinical and research areas. This method provides a direct noninvasive imaging of the targeted nerve and the tissue around it in real time. Furthermore, it allows anesthetists to observe the injected anesthetics for optimal distribution. However, there are still some major limitations to this method such as poor visibility of the standard needle tip and shaft, tricky location estimation of needle tip, and difficult needle alignment before and during insertion. This article presents the concept of a new application field of medical navigation for regional anesthesia using ultrasound imaging, to avoid the above-mentioned drawbacks. In addition, a laboratory experiment on a phantom to verify the effectiveness, safety, precision and handling of the navigation method in comparison with standard ultrasound-guided regional anesthesia is described. During the experiment ten test persons who have no experience in this field should touch a target in a phantom, avoiding contact with the simulated blood vessels and nerve. Each test person was asked to repeat the test five times with and without navigation assistance, respectively. Thereafter, a two-sample one-tailed paired t-test with a significance level of 1% was applied to statistically analyze the difference. The results show that navigation assistance significantly improves effectiveness, safety, precision and handling of ultrasound-guided regional anesthesia.