BLOOD OXYGENATION DEPENDENCE OF T-1 AND T-2 IN THE ISOLATED, PERFUSED RABBIT HEART AT 4.7T

An MR line scan protocol has been used to measure relaxation parameters (T-1 and T-2) in isolated, blood perfused rabbit hearts at various blood oxygenations, Hearts were retrogradely perfused at 37 degrees C with a cardioplegic solution (modified St, Thomas' solution) containing sheep red blood cells and adenosine (1 mM) to maximally vasodilate the coronary vascular bed, Arresting the hearts eliminated motion complications and minimized arteriovenous oxygenation differences, The authors have found that under conditions of stable flow, there is a strong correlation between T-2 in myocardial septa and hemoglobin (Hb) saturation, while tissue T-1 is virtually independent of blood oxygenation. These effects are believed to be due to the paramagnetic agent deoxyhemoglobin.