Quantitative T 2 mapping of the mouse heart by segmented MLEV phase‐cycled T 2 preparation

Purpose A high‐quality, reproducible, multi‐slice T 2 ‐mapping protocol for the mouse heart is presented. Methods A T 2 ‐prepared sequence with composite 90° and 180° radiofrequency pulses in a segmented MLEV phase cycling scheme was developed. The T 2 ‐mapping protocol was optimized using simulations and evaluated with phantoms. Results Repeatability for determination of myocardial T 2 values was assessed in vivo in n = 5 healthy mice on 2 different days. The average baseline T 2 of the left ventricular myocardium was 22.5 ± 1.7 ms. The repeatability coefficient for R 2  = 1/T 2 for measurements at different days was ΔR 2  = 6.3 s −1 . Subsequently, T 2 mapping was applied in comparison to late‐gadolinium‐enhancement (LGE) imaging, to assess 1‐day‐old ischemia/reperfusion (IR) myocardial injury in n = 8 mice. T 2 in the infarcts was significantly higher than in remote tissue, whereas remote tissue was not significantly different from baseline. Infarct sizes based on T 2 versus LGE showed strong correlation. To assess the time‐course of T 2 changes in the infarcts, T 2 mapping was performed at day 1, 3, and 7 after IR injury in a separate group of mice (n = 16). T 2 was highest at day 3, in agreement with the expected time course of edema formation and resolution after myocardial infarction. Conclusion T 2 prepared imaging provides high quality reproducible T 2 maps of healthy and diseased mouse myocardium. Magn Reson Med 72:409–417, 2014. © 2013 Wiley Periodicals, Inc.