Enhancement of red blood cell proton relaxation with chromium labeling

Alan D. Eisenberg, Thomas E. Conturo, Mark R. Mitchell, Mindy S. Schwartzberg, Ronald R. Price, Mark F. Rich, C. Leon Part Ain, A. Everette James

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6 Scopus citations


Nuclear medicine has utilized chromium (Cr) for decades to label red blood cells (RBCs). The purpose of this project was to determine whether sufficient paramagnetic Cr could be bound to red cells to influence proton relaxation significantly. We demonstrated that the Ti and T2 of RBCs can be substantially shortened by labeling them with paramagnetic Cr. Proton relaxation enhancement occurs when red cells are incubated with sodium chromate (VI) over a concentration range of 0.10 mM to 31.6 mM. Labeling with Cr at a concentration of 31.6 mM shortened the Ti of packed cells from 714 msec to 33 msec, and the T2 from 117 msec to 24 msec, as compared with nonlabeled red cells. In vitro hemolysis was significantly increased after labeling at 31.6 mM, but not at lower concentrations. Cr-induced proton relaxation enhancement varied with RBCs from different species, temperature, pH, and length of incubation. Ti values of kidneys containing labeled red cells (303 msec), or labeled cells diluted 10-fold with nonlabeled cells (479 msec), were decreased compared with kidneys containing only nonlabeled cells (600 msec). Finally, preliminary data indicate that the signal intensity of perfused renal tissue is significantly influenced in vivo by infusion of Cr-Iabeled RBCs. This study demonstrated that Cr labeling of RBCs sufficiently enhances red cell proton relaxation to provide excised organs containing red cells, of which 10% have been Cr-labeled, with shorter Ti and T2 values than organs containing nonlabeled cells. In addition, the ability of labeled cells to alter signal intensity in vivo suggests that Cr may have the potential to become an MRI contrast agent.

Original languageEnglish
Pages (from-to)137-143
Number of pages7
JournalInvestigative Radiology
Issue number2
StatePublished - Feb 1986


  • Chromium
  • Contrast enhancement
  • MRI
  • Red blood cell


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