Interleaved T1 and T2 relaxation time mapping for cardiac applications

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Abstract
Purpose To diagnose acute myocardial infarction (MI) with MRI, T1-weighted and T2-weighted images are required to detect necrosis and edema. The calculation of both T1 and T2 maps can be relevant for quantitative diagnosis. In this work, we present a simultaneous quantification of T1-T2 relaxation times of a short-axis view of the heart in a single scan. Materials and Methods An electrocardiograph (ECG)-triggered, navigator-gated, interleaved T1 and T2 mapping sequence was implemented for the quantification of the T1 and T2 values of phantoms, healthy volunteers, and three patients with acute MI. The proposed acquisition scheme consisted of an interleaved two-dimensional (2D) steady-state free precession (SSFP) sequence with three different modules: an inversion-recovery (IR) sequence with multiple time delays, followed by a delay of one cardiac cycle for magnetization recovery and a T2-preparation pulse with multiple echo-times for T2 quantification. Results Measurements of in vivo relaxation times were in good agreement with literature values. The interleaved sequence was able to measure T1 and T2 relaxation times of the myocardium. Conclusion The interleaved sequence acquires data for the calculation of T1 and T2 maps in only one scan without the need for registration. This technique has the potential to differentiate between acute and chronic MI by estimating the concentration of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) in the necrotic tissue and to assess the extent of edema from T2 maps. J. Magn. Reson. Imaging 2009;29:480–487.