Intravascular susceptibility agent effects on tissue transverse relaxation rates in vivo

Magn Reson Med. 2000 Dec;44(6):909-14. doi: 10.1002/1522-2594(200012)44:6<909::aid-mrm12>;2-u.


Since vascular architecture differs among tissues, it was hypothesized that the change in transverse relaxation rate produced by a given tissue concentration of susceptibility contrast agent also varies by tissue. This is relevant to strategies to map regional blood volume by MRI using indicator dilution techniques. R*(2) was measured in rat organs over a range of susceptibility agent concentrations at 1.5 T. Rat red blood cells loaded with dysprosium-DTPA-BMA served as an intravascular susceptibility agent. Tissue samples were frozen in vivo and dysprosium concentrations were independently measured using inductively coupled plasma atomic emission spectroscopy. The slope (k) of R*(2) vs. tissue dysprosium concentration in sec(-1) mM(-1) for myocardium was 97.1 (95% C.I. 77. 0-117.2), liver 122.6 (108.3-136.9), spleen 22.5 (8.8-36.3), kidney 68.1 (58.6-77.6), and skeletal muscle 77.9 (4.1-151.6); k was significantly different (P < 0.05) for all pairings except those with skeletal muscle. Therefore, relative values of tissue blood volume derived from dynamic images of first pass contrast effects may be in error because k is not constant for different conditions.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylcysteine / analogs & derivatives*
  • Acetylcysteine / analysis
  • Acetylcysteine / pharmacology
  • Analysis of Variance
  • Animals
  • Contrast Media / analysis
  • Contrast Media / pharmacology*
  • Dose-Response Relationship, Drug
  • Dysprosium / analysis
  • Dysprosium / pharmacology*
  • Erythrocytes
  • Female
  • Magnetic Resonance Angiography / methods*
  • Magnetic Resonance Angiography / statistics & numerical data
  • Microcirculation / chemistry
  • Microcirculation / drug effects
  • Pentetic Acid / analysis
  • Pentetic Acid / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Spectrophotometry, Atomic


  • Contrast Media
  • Dysprosium
  • Pentetic Acid
  • Acetylcysteine
  • S-benzyl-N-acetyl-L-cysteine