title: Gadolinium-bearing red cells as blood pool MRI contrast agents.
abstract: Human and rat red blood cells (RBCs) were loaded with gadolinium DTPA dimeglumine using an osmotic pulse technique to create a blood pool contrast agent for MRI. The resulting packed red cells contained 30.9 +/- 3.3 (1 SD) mmol Gd/liter for humans and 24.7 +/- 3.5 (1 SD) mmol Gd/liter for rats. Longitudinal relaxation rate constant of human RBCs increased from 2.0 +/- 0.1 to 145.6 +/- 36.2 s(-1); the transverse relaxation rate constant increased from 6.8 +/- 1.2 to 562 +/- 410 s(-1). For rat RBCs, R1 increased from 1.45 +/- 0.15 to 84.8 +/- 23.9 s(-1); R2 increased from 7.1 +/- 0.64 to 247 +/- 158 s(-1). Affinity for oxygen was slightly reduced (control P50 = 22.3 +/- 2.3 versus experimental P50 = 27.3 +/- 1.3, P < 0.01), as was mechanical deformability. No drop in relaxivities was seen after 5 days of storage. The apparent volume of distribution was 0.0164 +/- 0.003 liter/kg, biologic half-life 4.38 +/- 0.34 h, and total plasma clearance 0.003 +/- 0.0006 liter/kg/h. Compared with Gd-DTPA "free" in the plasma, tissue enhancement from RBCs was initially lower but was much prolonged. Preparation is simple enough to be reproduced by most laboratories.
authors.affiliation: Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Johnson
authors.forename: J Z
authors.initials: JZ
authors.lastname: Tao
authors.forename: R P
authors.initials: RP
authors.lastname: Kennan
authors.forename: J C
authors.initials: JC
authors.lastname: Gore
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D004912:Erythrocytes / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D006207:Half-Life; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D008855:Microscopy, Electron, Scanning; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA