MR IMAGING OF THE LYMPHATIC SYSTEM-DISTRIBUTION AND CONTRAST ENHANCEMENT OF GADODIAMIDE AFTER INTRADERMAL INJECTION

Abstract

We examined 24 lower extremities in 12 patients with lymphedema to evaluate thedistribution and enhancement of gadodiamide after intradermal injection for MR imaging oflymphatic pathways in lymphedematous patients. The lymphedema was bilateral in 8, unilateralin 4, and 3 patients suffered from lymphedema in the genital region. 9 mL of gadodiamide and 1mL of mepivacainhydrochloride 1% were divided into 5 portions and injected intradermally intothe dorsal aspect of each foot. For MR imaging, a 3D spoiled gradient-echo sequence(Volumetric Interpolated Breathold Examination, VIBE) was performed. We detected the beadedappearance of lymphatic vessels extending from the injection site in 22 lower extremities (92%).In 13 lower extremities (54%), lymphatic vessels of the upper leg could be visualized. A contrastenhancement was observed in 16 out of 24 inguinal lymph node groups (67%). After 15 minutesof contrast material application, concomitant venous enhancement was detected in all lowerextremities (100%). In 15 lower extremities (63%), collateral vessels with dermal back-flowareas between lymphatic vessels were seen. Thus, intradermal injection of gadodiamide allowsthe visualization of lymphatic pathways in patients with lymphedema. In comparison to thevenous system, lymphatic vessels show a tendency to have the highest contrast material uptake inthe later acquisitions of 35, 45, and 55 minutes after intradermal injection of gadodiamide.Furthermore, 3D MIP reconstructions supported the identification of the lymphatic vessels anddifferentiation from veins due to the different angles of view.