Portal vein thrombosis caused by microwave coagulation therapy for hepatocellular carcinoma: report of a case

Percutaneous stereotactic image-guided microwave ablation for malignant liver lesions

Thermal ablation has proven beneficial for hepatocellular carcinoma and possibly for colorectal liver metastases, but data is lacking for other liver metastases. Computer-assisted navigation can increase ablation efficacy and broaden its indications. We present our experience with percutaneous stereotactic image-guided microwave ablation (SMWA) for non-colorectal liver metastases (NCRLM), in form of a retrospective study including all SMWA for NCRLM from 2015 to 2017. Indication for SMWA was determined at a multidisciplinary tumorboard. End-points include recurrence, overall and liver-specific disease progression and complications. Twenty-three patients underwent 25 interventions for 40 lesions, including 17 neuroendocrine tumor, nine breast cancer, four sarcoma, two non-small cell lung cancer, three duodenal adenocarcinoma, one esophageal adenocarcinoma, one pancreatic adenocarcinoma, one ampullary carcinoma, one prostate carcinoma, and one renal cell carcinoma metastases. Median follow-up was 15 months (2-32). Incomplete ablation rate was 2.5% (1/40), local recurrence rate 10% (4/40). Three patients (12%) had minor complications. Overall disease progression was 73.9% (17/23), median disease-free survival 7 months (0-26) and overall survival 18 months (2-39). SIMWA is feasible, safe and minimally invasive for NCRLM in selected patients. While it might offer an alternative to resection or palliative strategies, the oncological benefit needs to be evaluated in a larger patient cohort.

Perivascular extension of microwave ablation zone: demonstrated using an ex vivo porcine perfusion liver model<sup/>

Microwave ablation (MWA) has been proposed to suffer less from the heat sink effect compared to radiofrequency ablation but has been reported to cause extension of the ablation zone along intrahepatic vessels in clinical practice. To study this effect in detail, eight fresh porcine livers were perfused in an ex vivo organ perfusion system. Livers were perfused with oxygenated, O-positive human blood at 37 °C. Perfusion was discontinued immediately before ablation in the non-perfused group (n = 4) whilst in the perfused group (n = 4) perfusion was maintained during MWA (140 W X 2 min). Large intrahepatic vessels (> 6 mm) were avoided using ultrasound. MWA zones were bisected within 30 min of perfusion termination and sections were fixed in formalin and stained with H&E and NADH to assess cell viability. Magnetic resonance imaging (MRI) was performed on two livers (one perfused, one non-perfused) to provide imaging correlation before sectioning. Twenty-one out of a total of 30 MW ablation zones (70%) showed extension of the ablation zone along a vessel. There was no statistically significant difference (p = 1) in the incidence of ablation zone extension between perfused (9/13, 69%) and non-perfused organs (12/17, 71%). MRI also demonstrated ablation zone extension along blood vessels correlating with macroscopy in two livers. NADH staining also confirmed extension of the ablation zone. Liver MWA appears to be commonly associated with propagated thermal injury along adjacent vessels and occurs independent of active blood flow. In order to avoid possible complications through non-target tissue injury, this effect requires further investigation.

Predictors of thrombosis in hepatic vasculature during microwave tumor ablation of an in vivo porcine model

PURPOSE

To evaluate and model the risk of in vivo thrombosis in each hepatic vessel type during hepatic microwave ablation as a function of vessel diameter, velocity, and vessel-antenna spacing.

MATERIALS AND METHODS

A single microwave ablation antenna was inserted into a single porcine lobe (n = 15 total) adjacent to a hepatic artery, hepatic vein, or portal vein branch. Conventional ultrasound and Doppler ultrasound were used to measure the vessel diameter, blood flow velocity, and vessel-antenna spacing. A microwave ablation zone was created at 100 W for 5 minutes. Thrombus formation was evaluated on ultrasound performed immediately after the procedure. Logistic regression was used to evaluate the predictive value of vessel diameter, blood flow velocity, and vessel-antenna spacing on vascular thrombosis.

RESULTS

Thrombosis was identified in 53% of portal veins, 13% of hepatic veins, and 0% of hepatic arteries. The average peak blood flow rate of the hepatic artery was significantly greater than the average peak blood flow rate of the hepatic vein and portal vein. Peak blood flow velocity < 12.45 cm/s, vessel diameter < 5.10 mm, and vessel-antenna spacing < 3.75 mm were strong predictors of hepatic vein thrombosis. However, these individual factors were not predictive of the more common portal vein thrombosis.

CONCLUSIONS

Hepatic arteries do not appear to be at risk for thrombosis during microwave ablation procedures. Portal vein thrombosis was more common than hepatic vein thrombosis during microwave ablation treatments but was not as predictable based on vessel diameter, flow velocity, or vessel-antenna spacing alone.

Rationale for clinical trials of coagulation: reactive drugs in hepatocellular carcinoma

Evidence for the regulation of cancer growth by components of the blood coagulation mechanism provides abundant opportunity for the development of novel hypotheses for the experimental treatment of malignancy. Information available on the heterogeneity in mechanisms of interaction between various cancer cell types, and procoagulant and fibrinolytic pathways, platelets, glycosaminoglycan-regulated growth factors and cell-adhesion molecules indicates that insightful clinical trial design may allow targeting of individual cancer cell types with agents capable of intercepting mechanisms of growth control that are relevant to specific tumor types. This paper reviews the evidence that the common anticoagulant, heparin, inhibits hepatocellular carcinoma cell proliferation and hepatocellular carcinoma tumor dissemination in experimental animals. Clinical trials of heparin performed to date have shown increased tumor response rates and survival in other tumor types. Expression of urokinase-type plasminogen activator by hepatocellular carcinoma cells enhances tumor cell proliferation, motility, invasiveness and metastatic dissemination. Inhibition of the urokinase-type plasminogen activator/plasmin system by protease inhibitors such as aprotinin (Trasylol, Bayer) have shown improvement in the clinical course of certain tumor types. These data suggest that drugs that are well-known in the field of vascular medicine may find a role in the treatment of hepatocellular carcinoma, a common tumor type that has resisted containment by other means.

Computational modelling of microwave tumour ablations

Microwave tissue heating is being increasingly utilised in several medical applications, including focal tumour ablation, cardiac ablation, haemostasis and resection assistance. Computational modelling of microwave ablations is a precise and repeatable technique that can assist with microwave system design, treatment planning and procedural analysis. Advances in coupling temperature and water content to electrical and thermal properties, along with tissue contraction, have led to increasingly accurate computational models. Developments in experimental validation have led to broader acceptability and applicability of these newer models. This review will discuss the basic theory, current trends and future direction of computational modelling of microwave ablations.

Complications of microwave ablation for liver tumors: results of a multicenter study

PURPOSE

New technologies for microwave ablation (MWA) have been conceived, designed to achieve larger areas of necrosis compared with radiofrequency ablation (RFA). The purpose of this study was to report complications by using this technique in patients with focal liver cancer.

METHODS

Members of 14 Italian centers used a 2.45-GMHz generator delivering energy through a cooled miniature-choke MW antenna and a standardized protocol for follow-up. They completed a questionnaire regarding number and type of deaths, major and minor complications and side effects, and likelihood of their relationship to the procedure. Enrollment included 736 patients with 1.037 lesions: 522 had hepatocellular carcinoma with cirrhosis, 187 had metastases predominantly from colorectal cancer, and 27 had cholangiocellular carcinoma. Tumor size ranged from 0.5 to 10 cm. In 13 centers, the approach used was percutaneous, in 4 videolaparoscopic, and in 3 laparotomic.

RESULTS

No deaths were reported. Major complications occurred in 22 cases (2.9%), and minor complications in 54 patients (7.3%). Complications of MWA do not differ from those RFA, both being based on the heat damage.

CONCLUSION

Results of this multicenter study confirmed those of single-center experiences, indicating that MWA is a safe procedure, with no mortality and a low rate of major complications. The low rate of complications was probably due to precautions adopted, knowing in advance possible risk conditions, on the basis of prior RFA experience.

Portal vein thrombosis

Portal vein thrombosis (PVT) can be a difficult clinical problem to assess and manage. A high index of suspicion is needed for a PVT diagnosis given the subtle presentation and potentially serious long-term complications. It should be considered a clue to the presence of one or several underlying disorders, including prothrombotic disorders, whether or not a local precipitating factor is identified. The accruing evidence shows that acute PVT can and probably should be treated with anticoagulation or thrombolytic agents in an effort to prevent extension of thrombus, mesenteric vessel occlusion, and portal hypertension. However, chronic PVT should be treated conservatively with measures to control major consequences related to portal hypertension. Anticoagulation therapy duration should be tailored to the identified predisposing factors.

The safety and efficacy of ablative techniques adjacent to the hepatic vasculature and biliary system

Ablative techniques may provide an alternative to resection in treating awkwardly placed hepatic malignancy adjacent to major vascular and biliary structures. The heat-sink effect may reduce efficacy adjacent to major vascular structures. Vascular occlusion improves efficacy but is associated with increased vascular and biliary complications. The safety and efficacy of ablation in these situations remain to be defined. Further studies comparing both safety and efficacy are needed.

Liver ablation techniques: a review

BACKGROUND

Ablation techniques for unresectable liver carcinomas have evolved immensely since their introduction. Results of studies involving these techniques are restricted to reports of patient case series, which are often not presented in a standardised manner. This review aims to summarise the major studies in ablation technologies and present them in a way that may make comparison between the major modalities easier.

METHODS

All major databases (Medline, Cochrane, Embase and Pubmed) were searched for studies using microwave, radiofrequency or cryoablation to treat unresectable liver tumours. Only studies with at least 30 patients and 3-year follow-up were included. Complication, recurrence and survival rates of all studies are summarised and presented.

RESULTS AND CONCLUSION

It is difficult to compare ablation modalities, as probe design and energy sources have evolved rapidly over the last decade. Ablation offers an invaluable palliative option and in some cases it may offer rates of cure approaching that of surgical resection with lower morbidity and mortality. Perhaps the time has come, therefore, for prospective large-scale randomised control trials to take place comparing ablation modalities to each other and surgical resection.

Efficacy and safety of microwave ablation for primary and secondary liver malignancies: a systematic review

This article reviews the therapeutic efficacy and complications of microwave ablation (MWA) in the treatment of primary and secondary liver malignancies. A PubMed search using keywords 'microwave', 'liver', 'malignancy', 'cancer' and 'tumour' was performed to identify articles related to MWA of liver malignancies published in English from 1975 to February 2008. MWA is an effective treatment options for both primary and secondary liver malignancies with survivals comparable with those of liver resections. Local recurrences can be managed with further ablation. Small tumour size, well-differentiated tumour and a reduced number of lesions are factors associated with good prognosis. Temporary occlusion of the portal venous and hepatic arterial flow may increase the size of ablation but the safety aspect requires further validation. MWA is a minimally invasive technique that has broadened the therapeutic option for patients with conventionally unresectable liver tumours with promising survival data. Future advances in the applicator design and treatment monitoring may further improve its efficacy and widen the indications.

Thrombosis of a Bifurcated Endograft Following Lower-Back Microwave Therapy

PURPOSE

To describe an unusual case involving thrombosis in an aortic endograft limb following microwave therapy (MWT) for lumbar pain.

CASE REPORT

A 77-year-old man had successful repair of an abdominal aortic aneurysm with a Vanguard endograft. He had been free of complications during the 3-year follow-up. Five days after the 36-month surveillance angiogram, the patient was treated with MWT for chronic left-sided lumbar pain due to vertebral arthrosis. Immediately after this session, the patient presented with acute ischemia in the left lower limb. Computed tomographic angiography showed a thrombosis of the left limb of the endograft. A femorofemoral crossover bypass was performed. No complication was observed in later surveillance.

CONCLUSIONS

It may be advisable to avoid MWT and other deep heating therapies in patients with endografts. This caution is applicable to other metallic stents.

Pylethrombosis Associated with Gastric Cancer in Moschcowitz's Disease: Successful Management with Anticoagulant. Report of a Case

Portal vein thrombosis secondary to gastric cancer has been rarely reported. The main difficulty is represented by the correct differential diagnosis between benign and malignant thrombus and therefore by its treatment. In this report we describe a 62-year-old woman with Moschcowitz's disease who developed pylethrombosis and gastric cancer. Preoperative examination confirmed the relationship between the portal vein thrombosis and Moschcowitz's disease. She underwent an aggressive surgical procedure for the gastric cancer and conservative treatment of the thrombosis with subcutaneus administration of 8000 IU/day of low molecular weight heparin (LMWH) at the time of diagnosis, interrupted eight hours before surgery and resumed eight hours after with 4000 IU/day. At discharge LMWH treatment was replaced with oral sodium warfarin home treatment to keep the international normalized ratio range between 2 and 3. Regression of the thrombosis with low molecular weight heparin was confirmed by computed tomography. The patient survived more than two years. We believe that patients with gastric cancer complicated by benign partial portal vein thrombosis could gain particular benefit from adjuvant anticoagulant treatment, so that the surgical approach can be limited to gastric cancer.

The emergent role of focal liver ablation techniques in the treatment of primary and secondary liver tumours

Only 20% of patients with primary or secondary liver tumours are suitable for resection because of extrahepatic disease or the anatomical distribution of their disease. These patients could be treated by ablation of the tumour, thus preserving functioning liver. This study presents a detailed review of established and experimental ablation procedures. The relative merits of each technique will be discussed and clinical data regarding the efficacy of the techniques evaluated. A literature search from 1966 to 2003 was undertaken using Medline, Pubmed and Web of Science databases. Keywords were Hepatocellular carcinoma, liver metastases, percutaneous ethanol injection, cryotherapy, microwave coagulation therapy, radiofrequency ablation, interstitial laser photocoagulation, focused high-intensity ultrasound, hot saline injection, electrolysis and acetic acid injection. Ablative techniques offer a promising therapeutic modality to treat unresectable tumours. Large-scale randomised controlled trials are required before widespread acceptance of these techniques can occur.

Effects of intraaterial chemoembolization combined with percutaneous microwave coagulation on hepatocellular carcinoma: a clinical and experimental study

AIM: To evaluate the role of microwave coagulation for liver cancer after occlusion of hepatic artery in animal experiment and clinical study.

METHODS: Total 24 suitable hepatic lobes of ten dogs were separated into two groups. Microwave coagulation alone (control group) or after hepatic artery occlusion (experiment group) was performed respectively. The power of irradiation was 50 W and the duration was 300 and 400 seconds. Clinically, 25 patients with hepatocellular carcinoma (30 nodules) were treated with PMCT after TACE. The TACE was performed 1-3 times and PMCT 1-2 times totally in every patients.

RESULTS: In animal experiment, the coagulated area was elliptic in control group and was elliptic or round in experimental group. The volume of coagulated tissue in experimental group was 3.8 times bigger than that in control. Clinically, all the lesions in contrast-enhanced CT showed slight enhancement or no enhancement after treatment. Intratumoral blood flow decreased significantly in 6 patients and disappeared in 20 patients. In 19 patients with elevated a-fetoprotein, the level decreased in all patients and was normalized in 14. There were no significant side- effects.

CONCLUSION: PMCT after TACE can significantly enlarge the necrosis volume of microwave coagulation, and promote the efficacy of treatment for hepatocellular carcinoma.