Magnetic resonance imaging of lymphatic vessels without image subtraction: A practicable imaging method for routine clinical practice?

OBJECTIVE: To assess the feasibility of a time-efficient, high-resolution magnetic resonance lymphangiography (HR MRL) protocol without image subtraction for the detection of lymphatic vessels in patients with primary and secondary lymphedema. METHODS: Three consecutive patients with lymphedema of the lower extremities (2 primary bilateral, 1 secondary unilateral) underwent HR MRL without image subtraction. An amount of 9 mL of gadodiamide and 1 mL of mepivacaine hydrochloride 1% were subdivided into 5 portions and injected intracutaneously into the dorsal aspect of each foot outside the scanner before image acquisition. Magnetic resonance imaging was performed with a 1.5-T system equipped with high-performance gradients. For HR MRL, a 3-dimensional, spoiled gradient-echo sequence (Volumetric Interpolated Breath-hold Examination) was used. The extent and distribution of the lymphedema was evaluated using a heavily T2-weighted, 3-dimensional turbo-spin echo sequence. RESULTS: The HR MRL bilaterally detected the inguinal lymph nodes and the lymphatic vessels in the lower and upper leg in the 2 patients with primary lymphedema. In the patient with left-sided secondary lymphedema, the inguinal lymph nodes and the lymphatic vessels in the lower and upper leg were depicted on the right side. The diameter of the displayed lymphatic vessels varied between 1 and 5 mm. Three-dimensional, maximum-intensity projection images of different angles of view provided detailed outlining of the lymphatic vessels and differentiation from veins, which showed a lower signal intensity. CONCLUSION: The HR MRL without image subtraction is safe, technically feasible, and has the potential to become a diagnostic imaging tool in daily clinical practice because of its time efficiency.