Interstitial MR Lymphography with a Conventional Extracellular Gadolinium-based Agent: Assessment in Rabbits

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Abstract
To evaluate gadoterate meglumine as a contrast agent for interstitial magnetic resonance (MR) lymphography in combination with an adapted fast three-dimensional (3D) MR sequence. In 12 New Zealand White rabbits, 0.5 mL of undiluted gadoterate meglumine was injected subcutaneously into the dorsal foot pad (n = 9) or the foreleg (n = 3) bilaterally. Immediately after administration, a slight massage was performed at the injection site. Imaging was performed with a 3D spoiled gradient-recalled echo sequence (6.7/1.6 [repetition time msec/echo time msec]; field of view, 28.0 x 19.6; two signals acquired) similar to that used for 3D MR angiography. Thus, 3D maximum intensity projection images could be obtained. Images were obtained before injection and 5, 15, 30, 60, and 120 minutes after injection. In the hind legs, as many as four successive lymph node groups were depicted with maximum enhancement after 5-15 minutes for the popliteal lymph node group, 15-30 minutes for the inguinal lymph group, and 30-60 minutes for the iliac-paraaortal lymph node group; the iliac-paraaortal lymph node group was not consistently enhanced. In the forelegs, four successive lymph node groups, including axillary and mediastinal lymph node groups, showed marked gadolinium uptake, with maximum enhancement 5-15 minutes after injection. As a widely tested positive-enhancing T1 contrast agent with favorable safety features, gadoterate meglumine allows the depiction of three to four successive lymph node groups early after subcutaneous injection. With the sequence used, 3D MR lymphangiograms can be obtained.