Perivascular parenchymal extension of the ablation zone following liver microwave ablation

Thrombus formation in the suprahepatic inferior vena cava after microwave ablation in patients with hepatic metastasis: a case report

BACKGROUND

Microwave ablation (MWA) via ultrasound guidance is an important tool in the treatment of liver metastases. The most common postoperative complications are abdominal hemorrhage and bile leakage, whereas thrombosis in the suprahepatic inferior vena cava (IVC) is very rare, and clinical management is very difficult when the head end of the thrombus reaches the right atrium.

CASE PRESENTATION

This is a case report of a 52-year-old man with hepatic metastasis 21 months after radical resection of rectal cancer. After chemotherapy combined with targeted therapy, metastasis in segment IV (S4) of the liver was treated with microwave ablation. Two months after treatment, the hepatic metastasis in S4 showed a microwave ablation zone on MRI.Enhanced MRI showed venous thrombosis located in the left hepatic vein and IVC, and the head of the thrombus reached the right atrium. After two weeks of anticoagulation and thrombolytic treatment, the follow-up MRI showed that the venous thrombus had nearly disappeared.

CONCLUSION

When liver metastases are close to the hepatic vein, clinicians should pay attention to the occurrence of hepatic vein and IVC thrombosis following MWA; through early diagnosis and anticoagulation, pulmonary thromboembolism (PTE) can be minimized.

Irreversible Electroporation (IRE) in Locally Advanced Pancreatic Cancer: A Review of Current Clinical Outcomes, Mechanism of Action and Opportunities for Synergistic Therapy

Locally advanced pancreatic cancer (LAPC) accounts for 30% of patients with pancreatic cancer. Irreversible electroporation (IRE) is a novel cancer treatment that may improve survival and quality of life in LAPC. This narrative review will provide a perspective on the clinical experience of pancreas IRE therapy, explore the evidence for the mode of action, assess treatment complications, and propose strategies for augmenting IRE response. A systematic search was performed using PubMed regarding the clinical use and safety profile of IRE on pancreatic cancer, post-IRE sequential histological changes, associated immune response, and synergistic therapies. Animal data demonstrate that IRE induces both apoptosis and necrosis followed by fibrosis. Major complications may result from IRE; procedure related mortality is up to 2%, with an average morbidity as high as 36%. Nevertheless, prospective and retrospective studies suggest that IRE treatment may increase median overall survival of LAPC to as much as 30 months and provide preliminary data justifying the well-designed trials currently underway, comparing IRE to the standard of care treatment. The mechanism of action of IRE remains unknown, and there is a lack of data on treatment variables and efficiency in humans. There is emerging data suggesting that IRE can be augmented with synergistic therapies such as immunotherapy.

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.

Primary Leiomyosarcoma in the Inferior Vena Cava Extended to the Right Atrium: A Case Report and Review of the Literature

A 38-year-old woman had developed an abdominal distention, lower extremity edema, and dyspnea. Imaging examination revealed a large mass in the right atrium which was connected to lesions within the inferior vena cava. Although complete resection of the mass was not possible, partial surgical tumor resection was performed to avoid pulmonary embolization and circulatory collapse. Leiomyosarcoma was diagnosed histologically, and chemotherapy (doxorubicin) followed by radiotherapy was started. By reviewing papers published in the past 10 years that included 322 patients, we also discuss the clinical presentations and prognosis of leiomyosarcoma in the inferior vena cava.