Mannan-coated liposome delivery of gadolinium-diethylenetriaminepentaacetic acid, a contrast agent for use in magnetic resonance imaging.

Gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), a paramagnetic contrast agent for use in magnetic resonance imaging (MRI) was bound to stearylamine and incorporated into the liposomal membranes (Gd-DTPA liposomes). In addition, the Gd-DTPA liposomes were coated with mannan (cholesterol-aminoethylcarbamylmethyl mannan), a polysaccharide, to obtain the mannan-coated liposomes. An in vitro MRI study showed that the Gd-DTPA liposomes produced a greater intensity of contrast than did the Gd-DTPA solution with a reduced T1 relaxation time. Intravenous injection of the Gd-DTPA liposomes containing 153Gd or liposomes containing 153Gd or 14C-DTPA to mice showed an accumulation of Gd-DTPA primarily in the liver and lung. When the mannan-coated liposomes were administered, an increased uptake of Gd-DTPA by these tissues was demonstrated. The mannan-coated liposomes may enhance contrast of the liver in MRI at a lower dose of Gd-DTPA.