ABSTRACT: Thermal ablation with microwave or radiofrequency energy is an alternative modality for the treatment of oligometastatic liver disease that is not amenable to surgical resection. Percutaneous interventions in the subdiaphragmatic portion of the liver “hepatic dome” present unique technical challenges due to the close proximity to multiple vital structures such as diaphragm, pleura, lung parenchyma, pericardium, and thoracic cage. Additional difficulties arise due to the poor visualization and accessibility of the subcostal position of the hepatic dome. Several techniques can be utilized to augment the procedure and separate liver parenchyma from the adjacent structures, including hydrodissection, carbon dioxide insufflation, and angiographic balloon interposition. Pulmonary transgression can be safely avoided by creating an artificial pleural effusion or pneumothorax. We present the case of a 58-year-old male patient with metastatic colorectal cancer post chemotherapy and hemihepatectomy who developed a new metastatic solitary hepatic dome lesion. He was deemed not a candidate for surgical resection due to insufficient volume of the residual liver to allow for a wedge resection. We performed a successful safe thermal ablation of the target dome lesion with transthoracic intercostal approach. An iatrogenic pneumothorax was induced prior to the procedure to provoke partial lung collapse at the region of intended passage of the microwave antenna, displacing the lung parenchyma from the ablation site and preventing pulmonary heat injury.
IO Learning: 2020;8:E16-E19. Epub 2020 February 19.
Key words: hepatic dome interventions, iatrogenic pneumothorax, liver metastasis, microwave ablation
Surgical resection offers the best opportunity for survival in patients with colorectal cancer metastatic to the liver, with a 5-year survival rate up to 58%.1 In patients who underwent hepatectomy, tumor relapse in the remnant liver appears frequent and indications for repeat hepatectomy are limited.2 Thermal ablation is an alternative modality for the treatment of colorectal liver metastasis and involves destruction of cancer by heat. Thermal ablation includes radiofrequency ablation (RFA) and microwave ablation (MWA).3
Microwave ablation involves localized destruction of the tumor using heat generated by the electromagnetic waves in the microwave energy spectrum (300 MHz to 300 GHz). The oscillation of polar molecules produces frictional heating, generating tissue necrosis within solid tumors. Microwave coagulation therapy is suggested to be equally effective as hepatic resection in the treatment of multiple (2 to 9) hepatic metastases from colorectal carcinoma, whereas its surgical invasiveness is less than that of hepatic resection.4 Thermal ablation has lower complication rates, better health-related quality of life, and lower cost than surgery.5 In patients who meet requirements for resection but are at high surgical risk, thermal ablation may be a valid alternative to surgery.3 In the liver, thermal ablation is considered a second-line therapy for the treatment of medically or surgically inoperable oligometastatic colorectal metastases.6 Patients with unresectable colorectal metastases to the liver that progress despite systemic chemotherapy can undergo palliative treatment with chemoembolization or radioembolization with similar survival benefit.7 Radioembolization is indicated for hepatocellular carcinoma and liver-dominant colorectal and neuroendocrine tumor metastases that cannot be resected or ablated.8
Although percutaneous interventions in the liver are generally safe and efficient, treatment of the subdiaphragmatic portion of the liver “hepatic dome” presents unique technical challenges due to close proximity to multiple vital structures such as diaphragm, pleura, lung parenchyma, pericardium, and thoracic cage. Additional difficulties arise due to poor visualization and accessibility of the subcostal position of the hepatic dome, exacerbated by shallow breathing during sedation.
A 58-year-old male patient with colorectal cancer metastatic to the liver after neoadjuvant chemotherapy (FOLFOX – folinic acid, fluorouracil, and oxaliplatin), open left hepatectomy, and colectomy presented with a new solitary right hepatic lobe dome lesion concerning for new metastatic focus on positron emission tomography/computed tomography (PET/CT) (Figure 1). CT-guided core liver biopsy confirmed metastatic moderately differentiated adenocarcinoma of colorectal origin.
Due to the high lateral peripheral location of the hepatic dome lesion abutting hepatic capsule and diaphragm, a transpulmonic approach was chosen for the percutaneous access. To prevent the passage of the microwave antenna through the lung parenchyma, we induced an iatrogenic pneumothorax prior to MWA.
Under intermittent CT guidance, an 18 gauge Trocar needle (Cook Medical) with a blunt stylet was passed through the chest wall and into the pleural space. The blunt stylet was then removed, and a small amount of air was allowed to leak into the pleural space. An Amplatz wire was introduced through the Trocar into the pleural space and a 6 Fr pigtail catheter was positioned over the wire within the pleural cavity. Under intermittent CT guidance, an iatrogenic right pneumothorax was formed by filling room air via the pigtail catheter until the inferolateral tip of the right lower lobe retracted away from the right hepatic dome where the metastatic lesion was located (Figure 2).
Next, under intermittent CT guidance, two 17 gauge microwave ablation antenna needles passed through the chest wall, pleural space, and diaphragm, avoiding lung parenchyma and tissue locked within the hepatic dome lesion. A 7-minute, 65 Watt ablation was performed with both needles to obtain an intended 4.5 x 4.5 cm ablation zone (Figure 3).
A postprocedural unenhanced CT scan demonstrated immediate, nearly complete resolution of the right pneumothorax. The pleural pigtail catheter was attached to a water seal chamber and intrapleural air was suctioned. The chest tube was left attached to the water seal chamber overnight and removed the next day. The patient was discharged home in stable condition.
Oligometastatic liver lesions can be treated surgically or with thermal ablation. Thermal ablation has lower complication rates, better health-related quality of life, and lower cost than surgery; however, it has a higher local recurrence rate. Our patient had controlled primary malignancy, a solitary metastatic lesion in the liver, and potentially long progression-free survival, qualifying him for curative intent of the therapeutic intervention. The patient’s prior resection of the left hepatic lobe had, however, decreased his hepatic reserve and precluded surgical intervention, as it could have further compromised liver remnant function. Thus, locoregional therapy with thermal ablation was the best treatment option.
Interventional thermal ablative procedures in the hepatic dome are challenging and can be associated with complications related to adjacent organ injury, tumor seeding, and systemic air embolism.9 This is amplified in patients receiving general anesthesia, as the liver becomes increasingly subcostal in position due to shallow respirations brought on by sedation.10
The lesions of the hepatic dome can be accessed by subcostal, intercostal, or epipericardial fat pad approaches.9 The intercostal route frequently necessitates pleural or pulmonic transgression that can be avoided by creating artificial pleural effusion or pneumothorax.9 Hydrodissection, which involves injection of fluid into the peritoneal space around the liver, can be used to separate the hepatic dome from the diaphragm, pericardium, or abdominal/chest wall, preventing collateral tissue damage and diminishing postprocedural pain. A solution of 5% dextrose water is preferred over normal saline because it provides better electrical isolation, reduces unwanted heat dissipation to the adjacent organs, and is least likely to cause volume shifts due to its iso-osmolar nature. Intra-abdominal carbon dioxide insufflation and angiographic balloon interposition during hepatic ablations have limited studies on porcine models and suggest efficacy for diaphragmatic protection.
Thermal ablation of hepatic dome lesions is challenging due to difficult access and an increased potential for complications associated with diaphragmatic, lung, or pleural injury. Adjunctive techniques such as artificial pleural effusion or pneumothorax, hydrodissection, carbon dioxide insufflation, and angiographic balloon interposition can minimize the risks of the procedure.
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From the Department of Radiology, SUNY Upstate University Hospital, Syracuse, New York.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Address for Correspondence: Oleksandra Kutsenko, MD, Department of Radiology, SUNY Upstate University Hospital, 750 East Adams Street, Syracuse, NY 13210. Email: Kutsenko.Oleksandra@gmail.com