Review article

Intraoperative ultrasonography in liver cancer

The electronic diagnostic records of patients, primarily collected by hospitals, comprise valuable data for the development of recommender systems to support physicians in predicting the risks associated with various diseases. For some diseases, the diagnostic record data are not sufficient to train a prediction model to generate recommendations; this is referred to as the data sparsity problem. Cross-domain recommender systems offer a solution to this problem by transferring knowledge from a similar domain (source domain) with sufficient data for modeling to facilitate prediction in the current domain (target domain). However, building a cross-domain recommender system for medical diagnosis presents two challenges: (1) uncertain representations, such as the symptoms characterized by interval numbers, are often used in medical records, and (2) given two different diseases, the feature spaces of the two diagnostic domains are often disparate because the diseases are only likely to share a few symptoms. This study addresses these challenges by proposing a cross-domain recommender system, named information transfer for medical diagnosis (ITMD), to provide physicians with personalized recommendations for disease risks. In ITMD, a novel dissimilarity measurement was performed for diagnosis, represented as interval numbers. The space alignment technique eliminated the feature space divergence caused by different symptoms between two diseases, and the development of collective matrix factorization enabled knowledge transfer between the source and target domains. Experiments and a case study using real-world data demonstrated that ITMD outperforms four baselines and improves the accuracy of recommendations for disease risks in patients to support physicians in determining a final medical diagnosis.

The indocyanine green-photodynamic eye (ICG-PDE) system is useful to detect small hypervascular liver tumors, hepatocellular carcinoma (HCC), on the liver surface. This system may be also applied to improve determining the location of metastasis or tumor thrombus (TT). We herein report three case reports. ICG was administered preoperatively for functional testing and images of the tumor were observed during hepatectomy using a PDE camera.

The patient in case 1 exhibited advanced HCC with TT in the portal trunk. The TT in the right portal vein was clearly fluorescent by ICG-PDE and the right portal vein was adequately transected to remove TT. The patient in case 2 exhibited a large HCC in the right liver and the right adrenal gland was simultaneously swollen with enhancement. By confirming the fluorescent spot in the right adrenal gland, the metastasized lesion was completely resected. The patient in case 3 previously underwent central bi-segmentectomy, and lymph node metastasis and TT in the vena cava was observed during one-year follow-up. Although it was difficult to detect the definite margin of these lesions by the outline appearance, both lesions could be clearly observed with strong fluorescence and were completely resected.

ICG-PDE is a useful tool for detecting the precise tumor location even in extrahepatic tumor lesions, such as metastases or tumor thrombus, which is useful for deciding which parts to resect.

To improve the diagnostic accuracy for hepatic tumors on the liver surface, we investigated the usefulness of an indocyanine green-photodynamic eye (ICG-PDE) system by comparison with Sonazoid intraoperative ultrasonography (IOUS) in 117 patients. Hepatic segmentation by ICG-PDE was also evaluated.

ICG was administered preoperatively for functional testing and images of the tumor were observed during hepatectomy using a PDE camera. ICG was injected into portal veins to determine hepatic segmentation.

Accurate diagnosis of liver tumors was achieved with ICG-PDE in 75% of patients, lower than with IOUS (94%). False-positive and false-negative diagnosis rates for ICG-PDE were 24% and 9%, respectively. New small HCCs were detected in 3 patients. The ICG fluorescent pattern in tumors was strong staining in 41%, weak staining in 13%, rim staining in 20% and no staining in 26%. Hepatocellular carcinoma predominantly showed strong staining (61%), while rim staining predominated in cholangiocellular carcinoma (60%) and liver metastasis (55%). Hepatic segmental staining was performed in 28 patients, proving successful in 89%.

ICG-PDE is a useful tool for detecting the precise tumor location at the liver surface, identifying new small tumors, and determining liver segmentation for liver resection.

The boundary of the target hepatic segment within the liver parenchyma cannot be marked by the use of a conventional anatomic hepatectomy approach. This study describes a novel methylene blue staining technique for guiding the anatomic resection of hepatocellular carcinoma (HCC).

Between February 2009 and February 2012, anatomic hepatectomy was performed in 106 patients with HCC via a novel, sustained methylene blue staining technique. Sustained staining was achieved by injecting methylene blue into the distal aspect of the portal vein after exposing Glisson's sheath. The hepatic pedicle was immediately ligated, and the hepatic parenchymal transection was performed along the interface between methylene blue stained tissue and unstained tissue.

Anatomic hepatectomies included subsegmentectomy (n = 16), monosegmentectomy (n = 57), multisegmentectomy (n = 27), and hemihepatectomy (n = 6). The portal vein was injected successfully with methylene blue in 100% of cases, and complete staining of the target hepatic segment was achieved in 98 of 106 (92.5%) cases. Mean intraoperative bleeding was 360 ± 90 mL, and the postoperative complication rate was 24.5% (26/106). No perioperative mortality occurred. Operative margins were all negative on pathologic examination. Mean duration of postoperative follow-up was 40 months (range, 24–60). No local recurrence (around the operative margin) occurred.

This novel technique of achieving sustained staining by injecting methylene blue then immediately ligating the hepatic pedicle is simple and feasible. It can guide the selection of the operative margin during hepatic parenchyma transection to improve the accuracy of anatomic hepatectomy for the treatment of HCC.

Accurate antenna placement is essential for effective microwave ablation (MWA) of lesions. Laparoscopic targeting is made particularly challenging in liver tumours by the needle's trajectory as it passes through the abdominal wall into the liver. Previous optical three-dimensional guidance systems employing infrared technology have been limited by interference with the line of sight during procedures.

The aim of this study was to evaluate a newly developed magnetic guidance system for laparoscopic MWA of liver tumours in a pilot study.

Thirteen patients undergoing laparoscopic MWA of liver tumours gave consent to their participation in the study and were enrolled. Lesion targeting was performed using the InnerOptic AIM™ 3-D guidance system to track the real-time position and orientation of the antenna and ultrasound probe.

A total of 45 ablations were performed on 34 lesions. The median number of lesions per patient was two. The mean ± standard deviation lesion diameter was 18.0 ± 9.2 mm and the mean time to target acquisition was 3.5 min. The first-attempt success rate was 93%. There were no intraoperative or immediate postoperative complications. Over an average follow-up of 7.8 months, one patient was noted to have had an incomplete ablation, seven suffered regional recurrences, and five patients remained disease-free.

The AIM™ guidance system is an effective adjunct for laparoscopic ablation. It facilitates a high degree of accuracy and a good first-attempt success rate, and avoids the line of site interference associated with infrared systems.

Liver surgery has gone through the phases of wedge liver resection, regular resection of hepatic lobes, irregular and local resection, extracorporeal hepatectomy, hemi-extracorporeal hepatectomy and Da Vinci surgical system-assisted hepatectomy. Taking advantage of modern technologies, liver surgery is stepping into an age of precise liver resection. This review aimed to analyze the comprehensive application of modern technologies in precise liver resection.

PubMed search was carried out for English-language articles relevant to precise liver resection, liver anatomy, hepatic blood inflow blockage, parenchyma transection, and down-staging treatment.

The 3D image system can imitate the liver operation procedures, conduct risk assessment, help to identify the operation feasibility and confirm the operation scheme. In addition, some techniques including puncture and injection of methylene blue into the target Glisson sheath help to precisely determine the resection. Alternative methods such as Pringle maneuver are helpful for hepatic blood inflow blockage in precise liver resection. Moreover, the use of exquisite equipment for liver parenchyma transection, such as cavitron ultrasonic surgical aspirator, ultrasonic scalpel, Ligasure and Tissue Link is also helpful to reduce hemorrhage in liver resection, or even operate exsanguinous liver resection without blocking hepatic blood flow. Furthermore, various down-staging therapies including transcatheter arterial chemoembolization and radiofrequency ablation were appropriate for unresectable cancer, which reverse the advanced tumor back to early phase by local or systemic treatment so that hepatectomy or liver transplantation is possible.

Modern technologies mentioned in this paper are the key tool for achieving precise liver resection and can effectively lead to maximum preservation of anatomical structural integrity and functions of the remnant liver. In addition, large randomized trials are needed to evaluate the usefulness of these technologies in patients with hepatocellular carcinoma who have undergone precise liver resection.