title: Intravascular susceptibility agent effects on tissue transverse relaxation rates in vivo.
abstract: 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.
authors: Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
authors: K M
authors: KM
authors: Johnson
authors: J Z
authors: JZ
authors: Tao
authors: R P
authors: RP
authors: Kennan
authors: J C
authors: JC
authors: Gore
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000032:analysis / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D003287:Contrast Media / Q000032:analysis / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004419:Dysprosium / Q000032:analysis / Q000494:pharmacology*; D004912:Erythrocytes; D005260:Female; D018810:Magnetic Resonance Angiography / Q000379:methods* / Q000706:statistics & numerical data; D008833:Microcirculation / Q000737:chemistry / Q000187:drug effects; D004369:Pentetic Acid / Q000032:analysis / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013054:Spectrophotometry, Atomic
chemical_list: D003287:Contrast Media; D004419:Dysprosium; D004369:Pentetic Acid; D000111:Acetylcysteine; C029319:S-benzyl-N-acetyl-L-cysteine