Fast 23Na magnetic resonance imaging of acute reperfused myocardial infarction: Potential to assess myocardial viability

Raymond J. Kim, Joao A.C. Lima, Enn Ling Chen, Scott B. Reeder, Francis J. Klocke, Elias A. Zerhouni, Robert M. Judd

Research output: Contribution to journalArticlepeer-review

Abstract

Background: The ability of the myocyte to maintain an ionic concentration gradient is perhaps the best indication of myocardial viability. We studied the relationship of 23Na MRI intensity to viability and explored the potential of fast-imaging techniques to reduce 23Na imaging times in rabbits and dogs. Methods and Results: Eighteen rabbits underwent in situ coronary artery occlusion and reperfusion. The hearts were then either imaged following isolation and perfusion with cardioplegic solution (n=6), imaged in vivo (n=6), or analyzed for 23Na content and relaxation times (n= 12). Normal rabbits (n= 6) and dogs (n=4) were imaged to examine the effect of animal size on 23Na image quality. 23Na imaging times were 7, 11, and 4 minutes for isolated rabbits, in vivo rabbits, and in vivo dogs, respectively. Infarcted, reperfused regions, identified by triphenyltetrazolium chloride staining, showed a significant elevation in 23Na image intensity compared with viable regions (isolated, 42±5%. P<.02; in vivo, 95±6%, P<.001), consistent with increased tissue sodium content. Similarly, 23Na MR spectroscopy showed that [Na+] was higher in nonviable than viable myocardium (isolated, 99±4 versus 61±2 mmol/L; in vivo, 91±2 versus 38±1 mmol/L; P<.001 for both). Image signal-to-noise ratios were higher in dogs than rabbits despite shorter imaging times, primarily due to larger voxels. Conclusions: Following acute infarction with reperfusion, a regional increase in 23Na MR image intensity is associated with nonviable myocardium. Fast gradient-echo imaging techniques reduce 23Na imaging times to a few minutes, suggesting that 23Na MR imaging has the potential to become a useful experimental and clinical tool.

Original languageEnglish (US)
Pages (from-to)1877-1885
Number of pages9
JournalCirculation
Volume95
Issue number7
DOIs
StatePublished - Apr 1 1997

Keywords

  • infarction
  • magnetic resonance imaging
  • myocardium
  • sodium

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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