title: The effect of perfusion on T1 after slice-selective spin inversion in the isolated cardioplegic rat heart: measurement of a lower bound of intracapillary-extravascular water proton exchange rate.
abstract: Many NMR measurements of cardiac microcirculation (perfusion, intramyocardial blood volume) depend on some kind of assumption of intracapillary-extravascular water exchange rate, e.g., fast exchange. The magnitude of this water exchange rate, however, is still unknown. The intention of this study was to determine a lower limit for this exchange rate by investigating the effect of perfusion on relaxation time. Studies were performed in the isolated perfused cardioplegic rat heart. After slice-selective inversion, the spin lattice relaxation rate of myocardium within the slice was studied as a function of perfusion and compared with a mathematical model which predicts relaxation rate as a function of perfusion and intracapillary-extravascular exchange rate. A linear relationship was found between relaxation rate T(-1) and perfusion P normalized by perfusate/tissue partition coefficient of water, lambda: deltaT(-1) = m x deltaP/lambda with 0.82 < or = m < or = 1.06. Insertion of experimental data in the model revealed that a lower bound of the exchange rate from intra- to extravascular space is 6.6 s(-1) (4.5 s(-1), P < 0.05), i.e., the intracapillary lifetime of a water molecule is less than 150 ms (222 ms, P < 0.05). Based on this finding, the T1 mapping after slice-selective inversion could become a valuable noncontrast NMR method to measure variations of perfusion.
authors.affiliation: II. Medizinische Universitätsklinik Mannheim/Heidelberg, Germany.
authors.forename: W R
authors.initials: WR
authors.lastname: Bauer
authors.forename: F
authors.initials: F
authors.lastname: Roder
authors.forename: K H
authors.initials: KH
authors.lastname: Hiller
authors.forename: H
authors.initials: H
authors.lastname: Han
authors.forename: S
authors.initials: S
authors.lastname: Fröhlich
authors.forename: E
authors.initials: E
authors.lastname: Rommel
authors.forename: A
authors.initials: A
authors.lastname: Haase
authors.forename: G
authors.initials: G
authors.lastname: Ertl
mesh_terms: D000818:Animals; D003326:Coronary Circulation; D006439:Hemodynamics; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008433:Mathematics; D008962:Models, Theoretical; D009206:Myocardium / Q000737:chemistry*; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D014867:Water / Q000032:analysis
chemical_list: D014867:Water