A Technique for Rapid Single-Echo Spin-Echo T2 Mapping

A rapid technique for mapping of T-2 relaxation times is presented. The method is based on the conventional single-echo spin echo approach but uses a much shorter pulse repetition time to accelerate data acquisition. The premise of the new method is the use of a constant difference between the echo time and pulse repetition time, which removes the conventional and restrictive requirement of pulse repetition time >> T-1. Theoretical and simulation investigations were performed to evaluate the criteria for accurate T-2 measurements. Measured T(2)s were shown to be within 1% error as long as the key criterion of pulse repetition time/T-2 >= 3 is met. Strictly, a second condition of echo time/T-1 << 1 is also required. However, violations of this condition were found to have minimal impact in most clinical scenarios. Validation was conducted in phantoms and in vivo T-2 mapping of healthy cartilage and brain. The proposed method offers all the advantages of single-echo spin echo imaging (e.g., immunity to stimulated echo effects, robustness to static field inhomogeneity, flexibility in the number and choice of echo times) in a considerably reduced amount of time and is readily implemented on any clinical scanner. Magn Reson Med 64:536-545, 2010. (C) 2010 Wiley-Liss, Inc.