Dysprosium-bearing red cells as potential transverse relaxation agents for MRI.
The cytosol of intact human red blood cells was loaded with 28.1 +/- 3.4 mM of dysprosium DTPA-BMA using a hypoosmotic technique. When loaded cells were diluted with saline and control cells to give an average dysprosium concentration of 3.3 +/- 0.5 mM, the transverse relaxation rate constants R(*)(2) and R(2) increased. R(*)(2) increased from 7.5 +/- 0.9 sec(-1) to 356 +/- 50 sec(-1), and R(2) increased from 7.4 +/- 0.7 sec(-1) to 148 +/- 40 sec(-1). After lysing, R(*)(2) was 6.0 +/- 0.6 sec(-1) in the control and 13.4 +/- 1.5 sec(-1) in the mixture; R(2) was 6.4 +/- 1.1 sec(-1) and 9.8 +/- 2.4 sec(-1), respectively. Thus, the relaxivity effects were enhanced by sequestration of the dysprosium within intact red cells, and this effect was lost after lysis. At a circulating whole-blood concentration of 0.81 +/- 0.15 mM in rats, the liver signal intensity dropped 29.9% +/- 3.7% and kidney signal intensity dropped 19.4% +/- 8.7%. Dysprosium-loaded cells might be useful in the study of perfusion and tissue blood volume.
Johnson
K M
KM
Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA. kevin.johnson@yale.edu
Tao
J Z
JZ
Kennan
R P
RP
Gore
J C
JC
D000818:Animals; D002614:Chelating Agents / Q000493:pharmacokinetics; D004419:Dysprosium / Q000493:pharmacokinetics*; D004912:Erythrocytes; D006207:Half-Life; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D004369:Pentetic Acid / Q000493:pharmacokinetics; D051381:Rats
D002614:Chelating Agents; D004419:Dysprosium; D004369:Pentetic Acid