Carboxymethyl-dextran-gadolinium-DTPA as a blood-pool contrast agent for magnetic resonance angiography. Experimental study in rabbits.
OBJECTIVE
The authors evaluate the efficiency of various doses of a paramagnetic macromolecular contrast agent, a gadolinium (Gd)-DTPA-dextran conjugate, as a blood-pool contrast media, in a transverse three-dimensional time-of-flight (TOF) magnetic resonance (MR) angiography sequence of the abdominal aorta in rabbits.


METHODS
Imaging experiments were performed on a 1.5-T magnet, using a transverse three-dimensional TOF tilted optimized nonsaturating excitation (TONE) sequence. The macromolecular contrast media used was a carboxymethyl-dextran-Gd-DTPA (CMD-Gd-DTPA). Different concentrations of CMD-Gd-DTPA (0.005, 0.01, 0.03, 0.05 mmol Gd/kg) were evaluated. A comparative study using Gd-DOTA (0.01 and 0.1 mmol/kg) was performed. A visual analysis based on the gain in the visualized length of small arteries (renal arteries), and a quantitative analysis based on the percent contrast enhancement of the aorta plotted against distance in the slab from the top edge of the acquisition volume were obtained.


RESULTS
A signal-to-noise ratio enhancement of the distal part of the aorta and an improvement in the visualized length of the renal arteries were noted for concentrations of CMD-Gd-DTPA ranging form 0.01 to 0.05 mmol Gd/kg. Venous enhancement was noted for concentrations greater than 0.01 mmol Gd/kg when using CMD-Gd-DTPA or Gd-DOTA.


CONCLUSIONS
Carboxymethyl-dextran-Gd-DTPA reduced, in part, the saturation effect in a three-dimensional transverse TOF TONE MR angiography in rabbits. To prevent venous enhancement, observed with the higher concentrations used in this study, a decrease in the polydispersity of the polymer should be a goal in the future. Rapid extravasation of the low-molecular weight fraction of the polymer could explain the venous enhancement.
Loubeyre
P
P
Laboratoire de Radiologie Expérimentale (CNRS URA 1216), Lyon, France.
Canet
E
E
Zhao
S
S
Benderbous
S
S
Amiel
M
M
Revel
D
D
D000818:Animals; D001012:Aorta, Abdominal / Q000033:anatomy & histology*; D001783:Blood Flow Velocity; D003287:Contrast Media; D003911:Dextrans; D005682:Gadolinium; D019786:Gadolinium DTPA; D018810:Magnetic Resonance Angiography / Q000379:methods*; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D011817:Rabbits; D012077:Renal Artery / Q000033:anatomy & histology*
D003287:Contrast Media; D003911:Dextrans; D009942:Organometallic Compounds; D004369:Pentetic Acid; C014392:carboxymethyl dextran; D005682:Gadolinium; D019786:Gadolinium DTPA