Published in:
Open Access 01-10-2012 | Research Article
Quantitative T 2 * assessment of acute and chronic myocardial ischemia/reperfusion injury in mice
Published in: Magnetic Resonance Materials in Physics, Biology and Medicine | Issue 5/2012
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Object
Imaging of myocardial infarct composition is essential to assess efficacy of emerging therapeutics. T
2
*
mapping has the potential to image myocardial hemorrhage and fibrosis by virtue of its short T
2
*
. We aimed to quantify T
2
*
in acute and chronic myocardial ischemia/reperfusion (I/R) injury in mice.
Materials and methods
I/R-injury was induced in C57BL/6 mice (n = 9). Sham-operated mice (n = 8) served as controls. MRI was performed at baseline, and 1, 7 and 28 days after surgery. MRI at 9.4 T consisted of Cine, T
2
*
mapping and late-gadolinium-enhancement (LGE). Mice (n = 6) were histologically assessed for hemorrhage and collagen in the fibrotic scar.
Results
Baseline T
2
*
values were 17.1 ± 2.0 ms. At day 1, LGE displayed a homogeneous infarct enhancement. T
2
*
in infarct (12.0 ± 1.1 ms) and remote myocardium (13.9 ± 0.8 ms) was lower than at baseline. On days 7 and 28, LGE was heterogeneous. T
2
*
in the infarct decreased to 7.9 ± 0.7 and 6.4 ± 0.7 ms, whereas T
2
*
values in the remote myocardium were 14.2 ± 1.1 and 15.6 ± 1.0 ms. Histology revealed deposition of iron and collagen in parallel with decreased T
2
*
.
Conclusion
T
2
*
values are dynamic during infarct development and decrease significantly during scar maturation. In the acute phase, T
2
*
values in infarcted myocardium differ significantly from those in the chronic phase. T
2
*
mapping was able to confirm the presence of a chronic infarction in cases where LGE was inconclusive. Hence, T
2
*
may be used to discriminate between acute and chronic infarctions.