Nodal and Pedal MR Lymphangiography of the Central Lymphatic System: Techniques and Applications

Abstract

Novel lymphatic imaging and interventional techniques are increasingly used in the diagnostic workup and treatment of pathologies of the central lymphatic system and have opened a new field of interventional radiology. The mainstay of lymphatic imaging today is magnetic resonance lymphangiography (MRL). It provides information on the anatomy of the central lymphatic system, lymphatic flow, as well as lymphatic pathologies and therefore is a valuable tool for treatment planning. There are two techniques to perform contrast-enhanced MRL: nodal dynamic contrast-enhanced MRL (nodal DCE-MRL) and interstitial transpedal MRL (tMRL). Nodal DCE-MRL yields superior information on lymphatic flow dynamics and is therefore best suited for suspected lymphatic flow pathologies and lymphatic malformations. tMRL is a technically simpler alternative for central lymphatic visualization without the need for sonographically guided lymph node cannulation. This review article describes current MRL techniques with a focus on contrast-enhanced MRL, their specific advantages, and possible clinical applications in patients suffering from pathologies of the central lymphatic system.

Keywords: MR lymphangiography; chylothorax; chylous ascites; interventional radiology; lymphatic leakage; lymphatic malformation.

Fig. 1

Anatomy of the central lymphatic system. Coronal maximum intensity projections of ( a ) contrast-enhanced interstitial transpedal and ( b ) nodal MR lymphangiograms demonstrating typical anatomy without pathological findings ( short white arrows : lumbar lymphatics, long white arrow : cisterna chyli, arrowheads : thoracic duct, black arrow : termination of thoracic duct in the left venous angle).

Fig. 2

Example of a typical anatomical variant. Noncontrast MR lymphangiogram demonstrating duplications of the thoracic duct in the upper thorax as an anatomical variant without pathological value.

Fig. 3

Peripheral lymphatic system. Interstitial transpedal MR lymphangiograms of two patients suffering from ( a ) primary and ( b ) secondary lymphedema. ( a ) Lymph vessel hyperplasia with dilated and tortuous lymph vessels and collateral pathways as well as dermal backflow. ( b ) Signs of lymph flow obstruction in a patient after inguinal lymphadenectomy with lymphatic backflow into cutaneous lymphatic networks and multiple focal areas of dermal backflow.

Fig. 4

Ultrasound-guided lymph node puncture. A 25- to 22-gauge needle is placed into the center of a lymph node for contrast application.

Fig. 5

Traumatic chylothorax. A 79-year-old patient with a high-volume therapy refractory right-sided chylothorax after resection of esophageal cancer. ( a ) Coronal MIP MRL after intranodal contrast application showing enhancement of retroperitoneal lymphatics, the cisterna chyli, and the thoracic duct up to its termination in the left venous angle. There is a postoperative leakage from the thoracic duct as the cause of chylothorax (arrow). ( b ) Corresponding X-ray lymphangiogram after transabdominal thoracic duct embolization. Notice that using the oily contrast agent, there is no visualization of the thoracic duct above the leakage site (arrow).

Fig. 6

Interstitial transpedal MRL of a 59-year-old patient with therapy refractory chylous ascites after esophagectomy. ( a–d ) Axial slices and ( e, f ) coronal MIP reconstruction of T1-weighted MRL after contrast application showing enhancement of the cisterna chyli and the thoracic duct (arrows) with complete transection of the thoracic duct in the upper abdomen as the cause of chylous ascites. There is consecutive massive extravasation of contrast into the abdominal cavity with enhancement of the ascitic fluid on late images (arrow heads on a–d and f ).

Fig. 7

Peripheral lymphatic leakage. Interstitial transpedal contrast-enhanced MRL of a 57-year-old patient suffering from a refractory inguinal cutaneous lymphatic fistula after lymph node dissection due to lymphoma 6 weeks ago. ( a, b ) Enhancement of ventromedial lymphatics of the left leg. There is inguinal extravasation from an injured lymphatic vessel ( arrow ) which is drained via an indwelling catheter ( arrow heads ). There is also faintly preserved central run-off via intact lymphatics. ( c ) Two areas with dermal backflow ( short arrows ) as a sign of peripheral lymphedema.

Fig. 8

Nontraumatic chylothorax. Interstitial transpedal contrast-enhanced MRL of a 35-year-old female suffering from refractory bilateral chylothorax and chylopericardium (already drained). ( a, b: axial, c, d: coronal ) Normal enhancement of the thoracic duct with chylolymphatic reflux from the left venous angle into the mediastinum and pulmonary hila as the cause of chylous effusions. ( e ) Oily X-ray lymphangiography corroborates MRL findings. Chylous effusions ceased immediately after thoracic duct embolization.

Fig. 9

Lymphatic flow pathology. Nodal DCE-MRL of a preterm 6-month-old male suffering from Noonan's syndrome with refractory bilateral chylothorax and chylopericardium. Coronal MIP reconstructions of an early ( a ) and a later ( b ) dynamic postcontrast series. There is no visible termination of the thoracic duct or relevant venous enhancement as signs of outflow obstruction. Notice the massive chylolymphatic backflow via alternate lymphatic pathways into the lungs (especially on the right side; arrow), the mediastinum, the thoracic wall, and cervical soft tissues.

Fig. 10

Lymphatic malformation. A 67-year-old man with spontaneous right-sided chylothorax. Axial T1-weighted contrast-enhanced transpedal MR lymphangiography ( a–d ) and corresponding digital X-ray lymphangiogram ( e ). MRL and X-ray lymphangiography demonstrates cystic lymphangiectasia in the posterior mediastinum ( short arrows ) as well as a normal caliber thoracic duct ( long arrows ) above and below the pathologically dilated lymphatics. Chylothorax resolved completely after embolization.