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Abstract Background T 2 and T 2 * mapping are crucial components of quantitative magnetic resonance imaging, offering valuable insights into tissue characteristics and pathology. Single‐shot methods can achieve ultrafast T 2 or T 2 * mapping by acquiring multiple readout echo trains. However, the extended echo trains pose challenges, such as compromised image quality and diminished quantification accuracy. Purpose In this study, we develop a single‐shot method for ultrafast T 2 and T 2 * mapping with reduced echo train length. Methods The proposed method is based on ultrafast single‐shot spatiotemporally encoded (SPEN) MRI combined with reduced field of view (FOV) and spiral out‐in‐out‐in (OIOI) trajectory. Specifically, a biaxial SPEN excitation scheme was employed to excite the spin signal into the spatiotemporal encoding domain. The OIOI trajectory with high acquisition efficiency was employed to acquire signals within targeted reduced FOV. Through non‐Cartesian super‐resolved (SR) reconstruction, 12 aliasing‐free images with different echo times were obtained within 150 ms. These images were subsequently fitted to generate T 2 or T 2 * mapping simultaneously using a derived model. Results Accurate and co‐registered T 2 and T 2 * maps were generated, closely resembling the reference maps. Numerical simulations demonstrated substantial consistency ( R 2 > 0.99) with the ground truth values. A mean difference of 0.6% and 1.7% was observed in T 2 and T 2 *, respectively, in in vivo rat brain experiments compared to the reference. Moreover, the proposed method successfully obtained T 2 and T 2 * mappings of rat kidney in free‐breathing mode, demonstrating its superiority over multishot methods lacking respiratory navigation. Conclusions The results suggest that the proposed method can achieve ultrafast and accurate T 2 and T 2 * mapping, potentially facilitating the application of T 2 and T 2 * mapping in scenarios requiring high temporal resolution.
Jin et al. (Wed,) studied this question.