Assessment of myocardial edema and area at risk in a rat model of myocardial infarction with a faster T2 mapping method

Abstract

Background The common T2 mapping is not suitable for the use in rat heart with high heart rate, unless data are acquired in multiple cardiac cycles. Purpose To evaluate a simplified T2 mapping method for faster assessment of myocardial edema and area at risk in a rat model of myocardial infarction. Material and Methods The simplified T2 mapping method (TR/TE, 1500 ms/10, 20, 30 ms) was implemented at a 7.0T MRI system. The accuracy of T2 mapping was compared with a standard T2 mapping method (TR, 2500 ms, 16 TEs equally spaced from 11 ms to 176 ms) in thigh muscles in rats ( n = 6) and a phantom. This method was further evaluated in normal rats ( n = 8) and rats with myocardial infarction ( n = 8). Late gadolinium enhancement images were also acquired in the rats with myocardial infarction. Results T2 values of simplified T2 mapping in the muscles and phantom were 27.3 ± 2 ms and 26.5 ± 1.1 ms, which were similar to the T2 values obtained by the standard T2 mapping method (28.1 ± 1.4 ms, P > 0.05; 26.9 ± 1.7 ms). No significant difference in T2 distribution (different segments and slices from base to apex) in the whole heart was found in normal rats (25.6 ± 3.3 ms, P > 0.05). The mean T2 value in the myocardial edema regions of myocardial infarction rats (37 ± 4.9 ms) was significantly higher than that of the normal rats (25.6 ± 3.3 ms, P < 0.001). The T2 value in the myocardial infarction core of myocardial infarction rats (39.9 ± 3.6 ms) was significantly higher than that of area at risk (34.7 ± 2.9 ms, P < 0.001). Conclusion The simplified myocardial T2 mapping is technically feasible and accurate, and can readily detect myocardial edema and area at risk in rats with high heart rate.