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

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. © The Foundation Acta Radiologica 2014.