Infarct size is overestimated by contrast-enhanced CMR in the acute phase but not at 7 days when compared with histopathology
© Jablonowski et al.; licensee BioMed Central Ltd. 2014
Published: 16 January 2014
Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) is considered the gold standard for quantification of myocardial infarction in vivo. Myocardium with increased fractional distribution volume (fDV) due to acute necrosis or chronic scar exhibit hyperenhancement relative to viable myocardium when using a gadolinium-based extracellular contrast agent. Previous studies have shown conflicting results regarding the existence of a reversibly injured peri-infarction zone (PiZ) early after acute myocardial infarction (MI). Therefore, the aim of this experimental animal study was to measure infarct size in relation to histopathology acute and 7 days after MI and relate these findings to assessment of relative fDV in different parts of the myocardium.
A total of 17 pigs were subjected to a 40-minute LAD occlusion followed by 6 hours (n = 9) or 7 days (n = 8) of reperfusion. Gadolinium-DOTA was injected for in vivo and high resolution ex vivo MI quantification by CMR. In addition, a radioactive tracer (99 mTc-DTPA) was injected for determination of relative fDV (relative to normal myocardium) using quantification of radioactive counts in tissue samples taken from the myocardium at risk (MaR), the PiZ and the infarct core. Infarct size was also assessed by triphenyltetrazolium chloride (TTC) staining. Finally, the TTC stained slices of the ex vivo heart with TTC signs of infarction were re-scanned to enable a true slice-by-slice comparison.
There is an overestimation of MI size by CMR compared to TTC in the acute phase but not after 7 days following acute MI. This is associated with a significantly higher fDV in the peri-infarction zone in the acute phase compared to 7 days later, indicating recovery of reversibly injured myocardium.
Swedish Research Council, Swedish Heart Lung Foundation, Region of Scania, Medical Faculty at Lund University.
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