Benign Liver Tumors

Background

Due to the frequent use of medical imaging including ultrasonography, the incidence of benign liver tumors has increased. There is a large variety of different solid benign liver tumors, of which hemangioma, focal nodular hyperplasia (FNH), and hepatocellular adenoma (HCA) are the most frequent. Advanced imaging techniques allow precise diagnosis in most of the patients, which reduces the need for biopsies only to limited cases. Patients with benign liver tumors are mostly asymptomatic and do not need any kind of treatment. Symptoms can be abdominal pain and pressure effects on adjacent structures. The 2 most serious complications are bleeding and malignant transformation.

Summary

This review focuses on hepatic hemangioma (HH), FNH, and HCA, and provides an overview on clinical presentations, surgical and interventional treatment, as well as conservative management. Treatment options for HHs, if indicated, include liver resection, radiofrequency ablation, and transarterial catheter embolization, and should be carefully weighed against possible complications. FNH is the most frequent benign liver tumor without any risk of malignant transformation, and treatment should only be restricted to symptomatic patients. HCA is associated with the use of oral contraceptives or other steroid medications. Unlike other benign liver tumors, HCA may be complicated by malignant transformation. HCAs have been divided into 6 subtypes based on molecular and pathological features with different risk of complication.

Key Message

The vast majority of benign liver tumors remain asymptomatic, do not increase in size, and rarely need treatment. Biopsies are usually not needed as accurate diagnosis can be obtained using modern imaging techniques.

Hybrid-ALPPS followed by Ante Situm with Cardiopulmonary Bypass: Rapid Liver Augmentation and Complex Surgery

BACKGROUND

Tumors invading the inferior vena cava (IVC) and hepatic veins pose a challenge for surgeons. Hannoun et al.1 were able to show that the resection of these tumors can be done under hypothermia in the Ante-Situm position. Additionally, not only the localization of the tumor but the remaining volume of the remnant liver (FLR) needs to be considered. Schnitzbauer et al.2 were able to induce massive liver hypertrophy in a short period, combining an in-situ split with a portal vein ligation (ALPPS). As this controversial technique has evolved, a safe ALPPS can be performed nowadays.3 To our knowledge, this is the first case that combines a laparoscopic partial ALPPS with an extended resection requiring cardiopulmonary bypass (CPB).

METHODS

A 58-year-old female presented with a known chronic hepatitis C suffered from a pulmonary embolism, caused by a large, central hepatocellular carcinoma (HCC) with invasion of the suprahepatic IVC and continuous growth into the right atrium (RA). Due to the small FLR, we performed a laparoscopic hybrid-partial-ALPPS with an embolization of the right portal vein. We were able to remove the mass with an Ante-Situm position and resection of the RA under CPB.

RESULTS

The postoperative course was complicated by posthepatic liver failure and bleeding. However, after 28 days the patient was discharged in a good medical condition.

CONCLUSIONS

Although tumors invading the suprahepatic IVC and RA pose a surgical challenge, patients can be treated adequately with multidisciplinary management. Advanced HCCs have high recurrence rates; however, a R0 resection might improve overall survival. Wakayma et al. showed in their retrospective study with 13 patients a median survival of 30.8 months when a complete resection was performed.4 Our patient had a disease-free survival of 11 months and is still alive after 24 months. Taking the complexity of the operation and the oncological prospect with a probable recurrence into account, indication for surgery needs to be considered on an individual basis.

[Navigated liver surgery : Current state and importance in the future]

The preoperative computer-assisted resection planning is the basis for every navigation. Thanks to modern algorithms, the prerequisites have been created to carry out a virtual resection planning and a risk analysis. Thus, individual segment resections can be precisely planned in any conceivable combination. The transfer of planning information and resection suggestions to the operating theater is still problematic. The so-called stereotactic liver navigation supports the exact intraoperative implementation of the planned resection strategy and provides the surgeon with real-time three-dimensional information on resection margins and critical structures during the resection. This is made possible by a surgical navigation system that measures the position of surgical instruments and then presents them together with the preoperative surgical planning data. Although surgical navigation systems have been indispensable in neurosurgery and spinal surgery for many years, these procedures have not yet become established as standard in liver surgery. This is mainly due to the technical challenge of navigating a moving organ. As the liver is constantly moving and deforming during surgery due to respiration and surgical manipulation, the surgical navigation system must be able to measure these alterations in order to adapt the preoperative navigation data to the current situation. Despite these advances, further developments are required until navigated liver resection enters clinical routine; however, it is already clear that laparoscopic liver surgery and robotic surgery will benefit most from navigation technology.

Effects of bulk wave radiation on IDT admittance on 42 degrees YX-LiTaO3

This paper investigates the effects of bulk acoustic wave (BAW) radiation on the admittance of interdigital transducers (IDTs) with significant internal reflections of shear horizontal (SH) type leaky surface acoustic waves (SAWs) on 42 degrees YX-LiTaO3 (42-LT). Theoretical analysis is made by using the discrete Green function theory, and synchronous one-port resonators are analyzed. It is shown that the BAW radiation significantly affects the IDT characteristics even for resonators; under certain circumstances, BAWs launched from an IDT are converted into SH-type SAWs by the strong internal reflections, and they interact with the BAWs radiated by the IDT. Then, the net amount of the radiated BAW power is highly dependent upon the number of IDT finger pairs. For the precise simulation of devices based on the SH-type SAWs with strong internal reflections, the BAW radiation should carefully be taken into consideration. If the BAW radiation is ignored, the radiated power of the SH-type SAWs may seem to be negative above the BAW cut-off frequency.

SAW devices for consumer communication applications

An overview of surface acoustic wave (SAW) filter techniques available for different applications is given. Techniques for TV IF applications are outlined, and typical structures are presented. This is followed by a discussion of applications for SAW resonators. Low-loss devices for mobile communication systems and pager applications are examined. Tapped delay lines (matched filters) and convolvers for code-division multiaccess (CDMA) systems are also covered. Although simulation procedures are not considered, for many devices the theoretical frequency response is presented along with the measurement curve.