Liver ultrasound: A key procedure in the surgeon's toolbox

Imaging adjuvants in pediatric surgical oncology

Surgery is a crucial component of pediatric cancer treatment, but conventional methods may lack precision. Image-guided surgery, including fluorescent and radioguided techniques, offers promise for enhancing tumor localization and facilitating precise resection. Intraoperative molecular imaging utilizes agents like indocyanine green to direct surgeons to occult deposits of tumor and to delineate tumor margins. Next-generation agents target tumors directly to improve specificity. Radioguided surgery, employing tracers like metaiodobenzylguanidine (MIBG), complements fluorescent techniques by allowing for detection of tumors at a greater depth. Dual-labeled agents combining both modalities are under development. Three-dimensional modeling and virtual/augmented reality aid in preoperative planning and intraoperative guidance. The above techniques show great promise to benefit patients with pediatric tumors, and their continued development will almost certainly improve surgical outcomes.

Should surgeon-performed intraoperative ultrasound be the preferred test for detecting main pancreatic duct injuries in operative trauma cases?

BACKGROUND

The diagnostic performance of multiple tests for detecting the presence of a main pancreatic duct injury remains poor. Given the central importance of main duct integrity for both subsequent treatment algorithms and patient outcomes, poor test reliability is problematic. The primary aim was to evaluate the comparative test performance of computed tomography (CT), magnetic resonance cholangiopancreatography (MRCP), endoscopic retrograde cholangiopancreatography (ERCP), and intraoperative ultrasound (IOUS) for detecting main pancreatic duct injuries.

METHODS

All severely injured adult patients with pancreatic trauma (2010-2021) were evaluated. Patients who received an IOUS pancreas-focused evaluation, with Grades III, IV, and V injuries (main duct injury) were compared with those with Grade I and Grade II trauma (no main duct injury). Test performances were analyzed.

RESULTS

Of 248 pancreatic injuries, 74 underwent an IOUS. The additional mix of diagnostic studies (CT, MRCP, ERCP) was variable across grade of injury. Of these 74 IOUS cases for pancreatic injuries, 48 (64.8%) were confirmed as Grades III, IV, or V main duct injuries. The patients were predominantly young (median age = 33, IQR:21-45) blunt injured (70%) males (74%) with severe injury demographics (injury severity score = 28, (IQR:19-36); 30% hemodynamic instability; 91% synchronous intra-abdominal injuries). Thirty-five percent of patients required damage-control surgery. Patient outcomes included a median 13-day hospital length of stay and 1% mortality rate. Test performance was variable across groups (CT = 58% sensitive/77% specific; MRCP = 71% sensitive/100% specific; ERCP = 100% sensitive; IOUS = 98% sensitive/100% specific).

CONCLUSION

Intraoperative ultrasound is a highly sensitive and specific test for detecting main pancreatic duct injuries. This technology is simple to learn, readily available, and should be considered in patients who require concurrent non-damage-control abdominal operations.

LEVEL OF EVIDENCE

Diagnostic Test/Criteria; Level III.

Usefulness of intraoperative ultrasound examination for laparoscopic right-side colon cancer surgery: a propensity score-matched study

Complete mesocolic excision (CME) with central vascular ligation (CVL) in laparoscopic surgery for right-sided colon cancer (RSCC) requires a precise understanding of the vascular anatomy. The efficacy of intraoperative ultrasound (IUS) in the identification of blood vessels for RSCC surgery was not evaluated. The aim of this study was to compare the intraoperative and short-term outcomes of CME with CVL with or without IUS by laparoscopic surgery for RSCC. We performed IUS on 26 patients of RSCC and compared with a total of 124 patients who underwent the surgery for RSCC at our institution. Propensity score matching (PSM) was performed to reduce the confounding effects to imbalances in the use of IUS. The IUS identified the main feeding artery and the accompanying vein in all 26 cases. After PSM, the amount of intraoperative blood loss in the IUS group was significantly lower than that in the conventional group (5 ml vs. 30 ml, p = 0.035) and no significant difference of the postoperative complications was observed. The IUS reduced the risk of bleeding in the surgery for RSCC. The IUS is a safe and feasible technique that help the surgeons for anatomical understandings under real-time condition in the laparoscopic surgery of RSCC.

Anatomy preserving GAN for realistic simulation of intraoperative liver ultrasound images

In ultrasound-guided liver surgery, the lack of large-scale intraoperative ultrasound images with important anatomical structures remains an obstacle hindering the successful application of AI to ultrasound guidance. In this case, intraoperative ultrasound (iUS) simulation should be conducted from preoperative magnetic resonance (pMR), which not only helps doctors understand the characteristics of iUS in advance, but also expands the iUS dataset from various imaging positions, thereby promoting the automatic iUS analysis in ultrasound guidance. Herein, a novel anatomy preserving generative adversarial network (ApGAN) framework was proposed to generate simulated intraoperative ultrasound (Sim-iUS) of liver with precise structure information from pMR. Specifically, the low-rank factors based bimodal fusion was first established focusing on the effective information of hepatic parenchyma. Then, a deformation field based correction module was introduced to learn and correct the slight structural distortion from surgical operations. Meanwhile, the multiple loss functions were designed to constrain the simulation of the content, structures, and style. Empirical results of clinical data showed that the proposed ApGAN obtained higher Structural Similarity (SSIM) of 0.74 and Fr´echet Inception Distance (FID) of 35.54 compared to existing methods. Furthermore, the average Hausdorff Distance (HD) error of the liver capsule structure was less than 0.25 mm, and the average relative (Euclidean Distance) ED error for polyps was 0.12 mm, indicating the high-level precision of this ApGAN in simulating the anatomical structures and focal areas.

Americas Hepato-Pancreato-Biliary Association HPB Ultrasound and Advanced Technology post-graduate course: Overview and review

Background

Americas Hepato-Pancreato-Biliary Association (AHPBA) established the Hepato-Pancreato-Biliary (HPB) ultrasound (US) and Advanced Technology Post-Graduate Course in 2012 in response to a perceived gap in training and practice.

Methods

The HPB US and Advanced Technology Post-Graduate Course consists of both didactic and hands-on skills sessions. The didactic sessions are divided into foundational, organ-focused, and application content. Hands-on sessions are constructed to immediately practice skills in the simulation setting which were taught during the didactic sessions. Course participant demographic data (practice location and practice type) and participant evaluations were reported.

Results

Since the first course in 2012, 298 participants have taken the post-graduate course. Most participants reported the content quality, delivery effectiveness, and practice relevance to be either excellent or above average (93.6 %, 91.1 %, 93.6 %, respectively). Participants' motivations to take the course included to enhance skills, knowledge, to incorporate US into practice, or to obtain formal training or qualification/certification, or to teach.

Conclusion

The HPB US and Advanced Technology Post-Graduate Course has filled a gap in HPB US training for practicing HPB surgeons. The annual course has been well-received by participants (Kirkpatrick Level 1 Program Evaluation) and will continue to fill the gap in training in operative US for the HPB surgeon.

Key message

Americas Hepato-Pancreato-Biliary Association established the HPB Ultrasound and Advanced Technology Post-Graduate Course in 2012. The Course has been well-received by participants and will continue to address a gap in surgical HPB training.

Laparoscopic Microwave Ablation: Which Technologies Improve the Results

Liver resection is the best treatment for hepatocellular carcinoma (HCC) when resectable. Unfortunately, many patients with HCC cannot undergo liver resection. Percutaneous thermoablation represents a valid alternative for inoperable neoplasms and for small HCCs, but it is not always possible to accomplish it. In cases where the percutaneous approach is not feasible (not a visible lesion or in hazardous locations), laparoscopic thermoablation may be indicated. HCC diagnosis is commonly obtained from imaging modalities, such as CT and MRI, However, the interpretation of radiological images, which have a two-dimensional appearance, during the surgical procedure and in particular during laparoscopy, can be very difficult in many cases for the surgeon who has to treat the tumor in a three-dimensional environment. In recent years, more technologies have helped surgeons to improve the results after ablative treatments. The three-dimensional reconstruction of the radiological images has allowed the surgeon to assess the exact position of the tumor both before the surgery (virtual reality) and during the surgery with immersive techniques (augmented reality). Furthermore, indocyanine green (ICG) fluorescence imaging seems to be a valid tool to enhance the precision of laparoscopic thermoablation. Finally, the association with laparoscopic ultrasound with contrast media could improve the localization and characteristics of tumor lesions. This article describes the use of hepatic three-dimensional modeling, ICG fluorescence imaging and laparoscopic ultrasound examination, convenient for improving the preoperative surgical preparation for personalized laparoscopic approach.

Artificial intelligence for identification of focal lesions in intraoperative liver ultrasonography

PURPOSE

Intraoperative ultrasonography (IOUS) of the liver is a crucial adjunct in every liver resection and may significantly impact intraoperative surgical decisions. However, IOUS is highly operator dependent and has a steep learning curve. We describe the design and assessment of an artificial intelligence (AI) system to identify focal liver lesions in IOUS.

METHODS

IOUS images were collected during liver resections performed between November 2020 and November 2021. The images were labeled by radiologists and surgeons as normal liver tissue versus images that contain liver lesions. A convolutional neural network (CNN) was trained and tested to classify images based on the labeling. Algorithm performance was tested in terms of area under the curves (AUCs), accuracy, sensitivity, specificity, F1 score, positive predictive value, and negative predictive value.

RESULTS

Overall, the dataset included 5043 IOUS images from 16 patients. Of these, 2576 were labeled as normal liver tissue and 2467 as containing focal liver lesions. Training and testing image sets were taken from different patients. Network performance area under the curve (AUC) was 80.2 ± 2.9%, and the overall classification accuracy was 74.6% ± 3.1%. For maximal sensitivity of 99%, the classification specificity is 36.4 ± 9.4%.

CONCLUSIONS

This study provides for the first time a proof of concept for the use of AI in IOUS and show that high accuracy can be achieved. Further studies using high volume data are warranted to increase accuracy and differentiate between lesion types.

Brazilian Society of Surgical Oncology surgical standards for resectable colorectal cancer liver metastases

The management of colorectal cancer liver metastasis (CRLM) has become complex because of the increasing availability of medical, radiological, and surgical treatment options applied either alone or in combination. However, resection remains the only evidence-based curative therapy. These Brazilian Society of Surgical Oncology surgical standards are intended to guide clinicians in the decision-making process for modern surgical management of CRLM within a multidisciplinary team in an evidence-based framework, focusing on resectable disease.

Getting going: Incorporating ultrasound into an HPB practice

The incorporation of ultrasound into a hepatopancreatobiliary surgical practice is both exciting and potentially intimidating. Although it is relatively straightforward to obtain detailed intraoperative ultrasound training from a small variety of formal programs, didactic curriculum, and mentorship experiences, seamless integration of this new knowledge into a hepatopancreatobiliary practice can be more challenging than expected. Although this is particularly true when a graduate begins a new practice, it is also relevant when incorporating hepatopancreatobiliary ultrasound into a mature group practice environment. This review outlines knowing your environment, certification and competency, credentialing and privileging, transition to independent practice, and maintaining competence.

Mastery skill assessment in hepato-pancreato-biliary surgical ultrasound: It's a Matter of Entrustment

BACKGROUND

A formative hepato-pancreato-biliary (HPB) ultrasound (US) skills practicum is offered annually to graduating HPB fellows, using entrustment assessments for open (IOUS) and laparoscopic (LAPUS) US. It is hypothesized that validity evidence will support the use of these assessments to determine if graduating fellows are well prepared to perform HPB US independently.

METHODS

Expert faculty were surveyed to set Mastery Entrustment standards for fellow performance. Standards were applied to fellow performances during two annual US skills practicums.

RESULTS

11 faculty questionnaires were included. Mean Entrustment cut scores across all items were 4.9/5.0 and 4.8/5.0 and Global Entrustment cut scores were 5.0/5.0 and 4.8/5.0 for IOUS and LAPUS, respectively. 78.5% (29/37) fellows agreed to have their de-identified data evaluated. Mean fellow Entrustments (across all skills) were 4.1 (SD 0.6; 2.6-4.9) and 3.9 (SD 0.7; 2.7-5), while the Global Entrustments were 3.6 (SD 0.8; 2-5) and 3.5 (SD 1.0; 2-5) for IOUS and LAPUS, respectively.

CONCLUSIONS

Two cohorts of graduating HPB fellows are not meeting Mastery Standards for HPB US performance determined by a panel of expert faculty.