Quantitative T2 Mapping of the Mouse Heart by Segmented MLEV Phase-Cycled T2 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 degrees and 180 degrees 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 Delta R-2=6.3 s(-1). Subsequently, T-2 mapping was applied in comparison to late-gadolinium-enhancement (LGE) imaging, to assess 1-dayold 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. (C) 2013 Wiley Periodicals, Inc.