Ultrasound inflammation imaging in rats with myocardial ischemia–reperfusion: evaluation by non-specific targeted contrast microbubbles

Abstract

Background

Reports on ultrasound inflammation imaging with non-specific targeted microbubbles in the heart have been scarce. We investigated whether inflammation induced by myocardial ischemia–reperfusion in rats could be evaluated by ultrasound inflammation imaging with non-specific targeted microbubbles.

Methods

Six rats subjected to 30 min of occlusion of the left anterior descending artery (LAD) followed by 4 h of reperfusion (ischemia group) and 4 rats subjected to the sham operation (sham group) were used. Ultrasound inflammation imaging was performed 4 h after reperfusion, and non-circulating signal intensity (SI), which reflects the signal derived from microbubbles phagocytosed by neutrophils in inflamed tissue, was calculated by the SI difference between the initial and subsequent imaging both in the LAD and non-LAD areas. The accumulation of neutrophils was confirmed by myeloperoxidase (MPO) staining.

Results

Non-circulating SI in the LAD area was significantly greater for the ischemia group than the sham group [5.19 ± 2.19 (ischemia) vs. 0.31 ± 0.13 (sham) dB, p < 0.01]. Non-circulating SI in the LAD area was significantly higher than that in the non-LAD area when compared in the same rat of the ischemia group [5.19 ± 2.19 (LAD) vs. 0.18 ± 0.64 (non-LAD) dB, p < 0.01]. MPO-positive cells were confirmed in the LAD area of the ischemia group.

Conclusion

Inflammation induced by myocardial ischemia–reperfusion in rats could be quantitatively assessed by ultrasound inflammation imaging with non-specific targeted microbubbles.