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Oxygenation in the rabbit myocardium: assessment with susceptibility-dependent MR imaging
M K Atalay1, J R Forder, V P Chacko
1Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2195.
Purpose:
To determine the feasibility of using hemoglobin (Hb) desaturation as an indicator of myocardial oxygenation.
Materials And Methods:
High-resolution gradient-echo nuclear magnetic resonance (MR) images of isolated, blood-perfused rabbit hearts were obtained at various blood oxygenation levels. The hearts were perfused at 37 degrees C with a Langendorff apparatus modified for nuclear MR imaging. The perfusate contained bovine red blood cells in a cardioplegic solution that eliminated motion artifacts and minimized arteriovenous oxygenation differences. Hb saturation was varied (7%-100%) randomly. Perfusion pressure was continuously monitored, and blood samples were obtained.
Results:
There was a substantial correlation between image signal intensity in the myocardium and Hb saturation in the blood, believed to be due to susceptibility effects of the paramagnetic species deoxyhemoglobin.
Conclusion:
Direct and noninvasive determination of regional Hb saturation with susceptibility-dependent MR imaging may provide information regarding regional myocardial O2 content.