Evaluation of Gd-DTPA-labeled dextran as an intravascular MR contrast agent: imaging characteristics in normal rat tissues.
Dextran covalently linked to moieties of gadolinium diethylenetriamine pentaacetic acid (DTPA), for use as a macromolecular, intravascular blood pool marker for contrast material-enhanced magnetic resonance (MR) imaging was characterized by means of physicochemical and relaxivity measurements and MR imaging in healthy rats. Dextran labeled with 15 Gd-DTPA moities (molecular weight of approximately 75,000 d) had a T1 relaxivity at 0.25 T and 37 degrees C of 157.1 mmol-1.sec-1 per molecule and 10.5 mmol-1.sec-1 per gadolinium atom, more than twice that of unbound Gd-DTPA. Osmolality was 300-350 mOsm/kg at a gadolinium concentration of 0.01 mmol/L. Tissue enhancement was essentially linearly related to injected dose in the gadolinium dose range of 0.01-0.05 mmol/kg of body weight. Approximate typical enhancement values over baseline for normal tissues at 10 minutes after a gadolinium dose of 0.05 mmol/kg were as follows: cardiac muscle, adrenal gland, and liver, 40%-50%; lungs, 160%-200%; renal cortex, 130%; renal medulla, 240%; spleen, 75%; muscle, 15%; and brain, 5%-10%. Projection-subtraction images showed that dextran-(Gd-DTPA)15 remained intravascular for at least 1 hour after injection. The prolonged and easily appreciated levels of tissue enhancement with dextran-(Gd-DTPA)15, at a gadolinium dose less than that routinely used in Gd-DTPA, indicate further evaluation of this macromolecular marker.
Contrast Media Laboratory, University of California, San Francisco 94143-0628.
S C
SC
Wang
M G
MG
Wikström
D L
DL
White
J
J
Klaveness
E
E
Holtz
P
P
Rongved
M E
ME
Moseley
R C
RC
Brasch
D000818:Animals; D003911:Dextrans / Q000008:administration & dosage / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D005069:Evaluation Studies as Topic; D019786:Gadolinium DTPA; D007275:Injections, Intravenous; D008279:Magnetic Resonance Imaging; D008297:Male; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics; D004369:Pentetic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics; D051381:Rats; D011919:Rats, Inbred Strains
D003911:Dextrans; D009942:Organometallic Compounds; D004369:Pentetic Acid; D019786:Gadolinium DTPA