Fig. 1
Sequence design for myocardial T1ρ mapping in small animals. The high heart and respiratory rates require the use of prospective triggering in combination with breath gating. Usually a trigger on the R-wave and dynamic trigger delays are applied before the spin-lock (SL) preparation. The acquisition window in diastole is very short (≈20–30 ms), so that several readouts can only be carried out by using fast gradient echoes. To acquire a single T1ρ weighted image, the experiment has to be repeated several times (NI). For T1ρ mapping, imaging has to be repeated with different SL times (ND). The sequence parameters of the readout (Trec, TR, NR, α) have a decisive impact on the relaxation pathway of T1ρ. This is explained in Fig. 2 by considering the signal S1