MR lymphangiography using dendrimer‐based contrast agents: A comparison at 1.5T and 3.0T

Most macromolecular contrast agents (CAs) show lower r 1 and higher r 2 relaxivities at 3.0T than at 1.5T. MR lymphangiography in mice using a macromolecular G6 dendrimer‐based CA was serially performed and compared at both 1.5T and 3.0T. The r 1 and r 2 relaxivities of the G6 CA were 25 and 78/s/mM at 1.5T and 17 and 82/s/mM at 3.0T, respectively. The lymph node (LN)‐to‐fat ratios (LN signal intensity (SI)/fat SI) of T 1 ‐weighted 3D‐fast spoiled gradient‐echo (3D‐FSPGR) were 3.2 ± 0.4 (mean ± standard deviation (SD)) at 1.5T and 2.7 ± 0.3 at 3.0T ( P = 0.021), and the LN‐to‐fat ratios of T 2 / T 1 ‐weighted 3D‐fast imaging employing steady‐state acquisition with phase cycling (3D‐FIESTA‐C) were 1.8 ± 0.2 at 1.5T and 1.2 ± 0.4 at 3.0T ( P = 0.003). Although 3D‐FSPGR successfully delineated the LNs at both 1.5T and 3.0T, 3D‐FIESTA‐C at 3.0T failed to visualize the LNs. Magn Reson Med 57:431–436, 2007. © 2007 Wiley‐Liss, Inc.