Peripheral Magnetic Resonance Lymphangiography: Techniques and Applications.

Peripheral lymphedema is a chronic progressive and debilitating disorder that results from abnormal lymphatic drainage. Advances in microsurgical techniques have led to the development of new treatment options for lymphedema that benefit from preoperative imaging to select the most appropriate surgical repair. Magnetic resonance (MR) lymphangiography is a noninvasive imaging modality capable of providing high-resolution 3D images of the lower extremities to define the severity and extent of lymphedema and depict individual lymphatic channels. The MR examination consists of 2 primary sequences. The first is a 3D heavily T2-weighted sequence to depict the severity and extent of the lymphedema. The second is a fat-suppressed 3D spoiled gradient-echo sequence performed after the intracutaneous injection of an extracellular gadolinium-based MR contrast agent. As venous enhancement almost always occurs, one of the interpretative challenges is differentiating enhancing lymphatic channels from superficial veins. MR techniques that can help with venous contamination include the addition of a contrast-enhanced MR venogram to the examination protocol, or the use of an iron-based blood-pool contrast agent to selectively suppress venous enhancement.