Comparison of the contrast-enhancing properties of albumin-(Gd-DTPA) and Gd-DTPA at 2.0 T: and experimental study in rats

Albumin-(gadolinium-diethylenetriaminepentaacetic acid), albumin-(Gd-DTPA), a macromolecular MR contrast agent designed for intravascular distribution, was compared with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), an extracellular fluid agent, for imaging characteristics in normal rats at 2.0 T. Albumin-(Gd-DTPA) produced larger-intensity increases in myocardium (125%), liver (114%), and brain (21%), at a dose of 0.062 mmol Gd/kg than did Gd-DTPA at a dose of 0.2 mmol/kg. The duration and pattern of enhancement differed between the two compounds; the enhancement with albumin-(Gd-DTPA) persisted at relatively constant levels from 2 min to 1 hr. The Gd-DTPA tissue enhancement peaked at 2 min and had virtually disappeared at 60 min. Gd-DTPA better enhanced subcutaneous tissues, presumably because of capillary permeability and enhancement of the abundant extracellular fluid space. When albumin-(Gd-DTPA) is used, the strong persistent enhancement of the microvascular compartment is well demonstrated on subtracted images and supports potential application of albumin-(Gd-DTPA) for blood-volume and perfusion-dependent contrast enhancement of myocardium, liver, and brain.