Magnetic resonance lymphangiography localized computed tomography-guided percutaneous interstitial glue embolization for persistent post-operative chylous effusion

INTRODUCTION

Chylous effusion is most commonly caused by iatrogenic injury in the setting of thoracic surgery. It has been reported to occur in up to 0.42% of all general thoracic surgical procedures.^[1] Non-traumatic chylous effusions are more rare but can be seen in cases of malignancy, chronic lymphatic occlusion, systemic disease, and congenital malformation.^[2]

Thoracic duct embolization was initially pioneered by Constantin Cope with beginning research in animal models in the late 1990s. It has since become a well-accepted intervention in postoperative chylous effusion management, as an alternative to conservative management versus surgical exploration and ligation.^[3]

CASE REPORT

This patient is a 72-year-old gentleman presenting from an outside facility. He has a past medical history of a remote pituitary neuroendocrine tumor which was surgically resected and then treated subsequently with radiation therapy approximately 40 years ago. Ten years ago, he had right-sided bilobectomy (upper and middle) for resection of a pulmonary carcinoid tumor.

On a surveillance computed tomography (CT) of the chest, he was found to have an enlarged retrocrural lymph node in the inferior aspect of the middle mediastinum [Figure 1]. Positron emission tomography (PET)/CT demonstrated FDG avidity of this lymph node.

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Figure 1: Axial CT of 72-year-old gentleman, lower chest demonstrates an enlarged retrocrural lymph node (red arrow), which was both fluorodeoxyglucose-avid and DOTATATE-avid on subsequent positron emission tomography/CT examinations. Given the patient’s known prior malignancies, surgical excision of the node was pursued. CT: Computed tomography.

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Further imaging with PET/CT DOTATATE complicated the clinical picture as the retrocrural lymph node also demonstrated intense somatostatin uptake within the same retrocrural lymph node.

Given the imaging findings, the decision was made to proceed with surgical resection of the retrocrural node through a thoracoscopic approach. During the procedure, there was concern for a chyle leak which was attempted to be addressed by ligation intra-operatively.

Post-operatively, there was concern for chyle leak with persistent right-sided pleural effusions, which was confirmed with elevated pleural fluid triglyceride levels.

The patient was taken for a conventional fluoroscopic lymphangiogram and attempted thoracic duct embolization. The lymphatic leak was demonstrated at about the level of T11, with pooling of lipiodol within the right pleural space; however, there was minimal contrast opacification of anything resembling a cisterna chyli nor was the thoracic duct confidently opacified. During the procedure, an access needle was placed through an anterior transabdominal approach adjacent to the caudal surgical clips suspicious for the site of leak, and cyanoacrylate glue was injected directly into the space in an attempt to treat the lymphatic leak.

Despite this intervention under conventional fluoroscopic guidance, the patient had persistent chest tube output.

Following this, an MRL was performed which again showed macroscopic lymphatic leak into the right pleural space beginning at T10–T11 from a lymphatic channel immediately adjacent to the susceptibility artifact from the more cranial surgical clip [Figure 2]. In addition, there was no in-line flow from the cisterna chyli to the thoracic duct but rather collateral filling of the terminal thoracic duct in the region of the left venous angle from left retroperitoneal to left paraspinal lymphatic collaterals.

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Figure 2: (a) Coronal maximum intensity projection reconstruction and (b) axial MRL of 72-year old male demonstrates a macroscopic lymphatic leak into the right pleural space (red arrows). The leak extends from above the cisterna chyli (not appreciated on conventional lymphangiogram) adjacent to susceptibility artifact from surgical clips. MRL: Magnetic resonance lymphangiography.

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A second attempt at gluing was performed. The area of leak adjacent to the surgical clips seen on MRL was targeted for glue injection. This was slightly more cranial and lateral than the glue embolization performed during the initial conventional lymphangiogram. This was done first with a CT-guided needle placement before conversion to fluoroscopic guidance for glue injection/embolization [Figure 3]. This procedure was successful with subsequent resolution of the effusion.

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Figure 3: (a) Axial and (b) sagittal intra-procedural CT images of a 72 year old male demonstrating needle tip placement (blue arrows) using CT-fluoroscopic guidance to target the most superior/cranial surgical clips based on the area of persistent lymphatic leak identified on MRL. (c) Real time fluoroscopic guidance was then utilized during the injection of TRUFILL cyanoacrylate glue into the retrocrural space (yellow arrow). (d) Immediate post-injection coronal CT with maximum intensity projection reconstruction demonstrates the glue in a similar configuration and space to the leaking gadolinium contrast on prior MRL (green arrow). MRL: magnetic resonance lymphangiography, CT: Computed tomography.

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This retrospective case report is Institutional Review Board (IRB) exempt.

DISCUSSION

Most post-operative thoracic lymphatic leaks are treated with embolization of the entire thoracic duct. More recently, selective lymphatic duct embolization has been performed for the treatment of lymphatic leaks and flow disorders in an attempt to preserve normal in-line flow through the thoracic duct.^[4] Both techniques require catheterization of the thoracic duct either by direct transabdominal access or retrograde transvenous access. In this case, traditional transabdominal access was not felt to be possible given the lack of an identifiable cisterna or dilated lymphatic channel large enough below the level of the leak for access. Transvenous catheterization has variable access, with success rates reported to be as low as only 61.5% in one of the larger case series reported.^[5] MRL case emerged as an import imaging and problem-solving tool for assessing lymphatic anatomy and pathologies.^[6] In this case, MRL was invaluable in more precisely identifying the site of ongoing lymphatic leak, which allowed for more accurate needle placement and glue embolization. Moreover, the MRL demonstrated that while there was no in-line flow from the cisterna chyli to the thoracic duct, there was collateral filling of the terminal thoracic duct in the region of the left venous angle from left retroperitoneal to left paraspinal lymphatic collaterals. As such, it was known that there would be preserved central conducting lymphatic flow with direct interstitial glue embolization of the leak in the low mediastinum.

CONCLUSION

Precise MRL-localized interstitial glue embolization can be a safe and effective for the treatment of lymphatic leaks which cannot be treated with direct thoracic duct embolization or lymphatic side branch embolization due to anatomic variations or limitations.