Studies of Gd-DTPA relaxivity and proton exchange rates in tissue. Magn Reson Med 1994 Jul;32(1):66-76
Date
07/01/1994Pubmed ID
8084239DOI
10.1002/mrm.1910320110Scopus ID
2-s2.0-0028239980 (requires institutional sign-in at Scopus site) 310 CitationsAbstract
The image intensity in many contrast agent perfusion studies is designed to be a function of bulk tissue T1, which is, in turn, a function of the compartmental (vascular, interstitial, and cellular) T1s, and the rate of proton exchange between the compartments. The goal of this study was to characterize the compartmental tissue Gd-DTPA relaxivities and to determine the proton exchange rate between the compartments. Expressing [Gd-DTPA] as mmol/liter tissue water, the relaxivities at 8.45 T and room temperature were: saline, 3.87 +/- 0.06 (mM.s)-1 (mean +/- SE; n = 29); plasma, 3.98 +/- 0.05 (mM.s)-1 (n = 6); and control cartilage (primarily an interstitium), 4.08 +/- 0.08 (mM.s)-1 (n = 17), none of which are significantly different. The relaxivity of cartilage did not change with compression, trypsinization, or equilibration in plasma, suggesting relaxivity is not influenced by interstitial solid matrix density, charge, or the presence of plasma proteins. T1 relaxation studies on isolated perfused hearts demonstrated that the cellular-interstitial water exchange rate is between 8 and 27 Hz, while the interstitial-vascular water exchange rate is less than 7 Hz. Thus, for Gd-DTPA concentrations, which would be used clinically, the T1 relaxation rate behavior of intact hearts can be modeled as being in the fast exchange regime for cellular-interstitial exchange but slow exchange for interstitial-vascular exchange. A measured relaxivity of 3.82 +/- 0.05 (mM.s)-1 (n = 8) for whole blood (red blood cells and plasma) and 4.16 +/- 0.02 (mM.s)-1 (n = 3) for frog heart tissue (cells and interstitium) (with T1 and Gd-DTPA concentration defined from the total tissue water volume) supports the conclusion of fast cellular-extracellular exchange. Knowledge of the Gd-DTPA relaxivity and maintaining Gd-DTPA concentration in the range so as to maintain fast cellular-interstitial exchange allows for calculation of bulk Gd-DTPA concentration from bulk tissue T1 within a calculable error due to slow vascular exchange.
Author List
Donahue KM, Burstein D, Manning WJ, Gray MLAuthor
Kathleen M. Schmainda PhD Professor in the Biophysics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsCartilage, Articular
Cattle
Contrast Media
Gadolinium
Gadolinium DTPA
Heart
Humans
Magnetic Resonance Imaging
Models, Chemical
Organometallic Compounds
Pentetic Acid
Rana catesbeiana
Rats
Rats, Sprague-Dawley
Tissue Distribution