Noninvasive assessment of cardiac ischemic injury using 87Rb and 23Na MR imaging, 31P MR, and optical spectroscopy

The aim of the study was to compare and analyze different noninvasive indices of cell damage in the isolated pig heart model of regional ischemia. We used 23Na and 87Rb MR imaging to evaluate Na+/K+ balance, 31P MR spectroscopy to measure energetics, and optical spectroscopy to assess oxymyoglobin (MbO2). Hearts were subjected to 120‐min occlusion of the left anterior descending artery and were then reperfused for 120 min. Reperfusion resulted in an increase in 23Na (37 ± 18% of the posterior wall) and decrease in 87Rb (55 ± 15%) image intensities, partial recovery of PCr, ATP, the total phosphates, and MbO2 in the anterior wall. The above changes are consistent with the irreversible cell damage in the anterior wall, confirmed by lack of staining with triphenyltetrazolium chloride. Changes in Na+ and Rb+ in the infarct area inversely correlated and their ratio is a more sensitive index of cell injury than either of them alone. Magn Reson Med 44:899–908, 2000. Published 2000 Wiley‐Liss, Inc.