1H2O MR Relaxography of the Perfused Rat Heart
Poirier-Quinot M, He H, Springer C, Balschi J
Brigham and Women's Hospital, Harvard Medical School
This study measured 1H2O T1 relaxation times of isolated rat hearts perfused with steady-state GdDTPA concentrations. Relaxographic analysis of the 1H2O T1 decays and analysis with two site exchange modified Bloch equations (2SX) revealed intracellular (pi) and extracellular (pe) water populations (tissue water volume fractions) and the average lifetime of intracellular water molecules (&[tau]i). In the perfused heart we found: &[tau]i = 0.18 sec and pi = 0.24. Zero flow ischemia caused vascular collapse and a decrease in pe; &[tau]i increased to 0.28 sec. 1H2O relaxography can measure myocardial intra- and extracellular volumes and &[tau]i during normal and disease states.