Interstitial MR and CT lymphography with Gd-DTPA-co-alpha,omega-diaminoPEG(1450) and Gd-DTPA-co-1,6-diaminohexane polymers: Preliminary experience

Rationale and Objectives, The authors assessed the efficacy of two gadolini um-based polymers used as lymphotrophic contrast media for computed tomogra phy (CT) and magnetic resonance (MR) imaging. Materials and Methods. Two gadolinium-based polymers, gadolinium diethylene triaminepentaacetic acid (DTPA)-co-1,6-diaminohexane (NC 22181) and Gd-DTPA -co-alpha, omega-diamino-polyethylene glycol(1450) (NC-66368), were formula ted at a concentration of 80 mmol/L gadolinium. Doses of 0.1, 0.25, 1.0, or 2.0 mL per paw were administered subcutaneously into the hindpaws of norma l rabbits. Spin-echo T1-weighted MR imaging (1.5 T) of rabbit popliteal and iliac nodes was performed before and immediately, 10 minutes, 2-3 hours, a nd 24 hours after injection. CT was performed 2-3 hours after injection of the high doses only. Results. MR imaging revealed prompt enhancement of the popliteal nodes with both polymers at doses of 0.25 mL and above. For doses of 1.0 mL or less p er paw, nodal percentage enhancement was maximal at 2 hours and then declin ed at 24 hours. At the highest doses, however, a reservoir of subcutaneous contrast material remained at the injection site and resulted in peak enhan cement at 24 hours. At CT, popliteal node enhancement was faintly visible 2 -3 hours after the administration of NC 22181. At lower doses, no enhanceme nt was appreciable at CT. Conclusion. At 80 mmol/L formulations, the two gadolinium-based polymers pr ovide excellent popliteal nodal enhancement on MR images. In addition, high doses of one polymer (NC 22181) were sufficiently concentrated. In poplite al nodes to be visible on CT scans. Thus, this agent may be useful for both CT and MR lymphography.