Interleaved T(1) and T(2) relaxation time mapping for cardiac applications

Abstract

Purpose: To diagnose acute myocardial infarction (MI) with MRI, T(1)-weighted and T(2)-weighted images are required to detect necrosis and edema. The calculation of both T(1) and T(2) maps can be relevant for quantitative diagnosis. In this work, we present a simultaneous quantification of T(1)-T(2) relaxation times of a short-axis view of the heart in a single scan.

Materials and methods: An electrocardiograph (ECG)-triggered, navigator-gated, interleaved T(1) and T(2) mapping sequence was implemented for the quantification of the T(1) and T(2) 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 T(2)-preparation pulse with multiple echo-times for T(2) quantification.

Results: Measurements of in vivo relaxation times were in good agreement with literature values. The interleaved sequence was able to measure T(1) and T(2) relaxation times of the myocardium.

Conclusion: The interleaved sequence acquires data for the calculation of T(1) and T(2) 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 T(2) maps.