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

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