Figure 3. ECG-gated pulse sequence schemes for simulation of (A) MOLLI and (B) ShMOLLI at a heart rate of 60 bpm. SSFP readouts are simplified to a single 35° pulse each, presented at a constant delay time TD from each preceding R wave. The 180° inversion pulses are shifted depending on the IR number to achieve the desired first TI of 100, 180 and 260 ms in the consecutive IR experiments. The plots below represent the evolution of longitudinal Mz for short T1 (400 ms, thin lines) and long T1 (2,000 ms, thick lines). Note that long epochs free of signal acquisitions minimise the impact of incomplete Mz recoveries in MOLLI so that all acquired samples can be pooled together for T1 reconstruction. In ShMOLLI the validity of additional signal samples from the 2nd and 3rd IR epochs is determined by progressive nonlinear estimation. As originally published by BioMed Central in Piechnik S et al. Journal of Cardiovascular Magnetic Resonance 2010;12:69.¹⁰⁾.

IR = inversion recovery; MOLLI = modified Look-Locker inversion recovery; Mz = longitudinal magnetization; ShMOLLI = shortened modified Look-Locker inversion recovery; SSFP = steady-state free precession; TD = trigger delay.