Abdominal simultaneous 3D water T1 and T2 mapping using a free‐breathing Cartesian acquisition with spiral profile ordering

Abstract Purpose To develop a method for abdominal simultaneous 3D water () and () mapping with isotropic resolution using a free‐breathing Cartesian acquisition with spiral profile ordering (CASPR) at 3 T. Methods The proposed data acquisition combines a Look‐Locker scheme with the modified BIR‐4 adiabatic preparation pulse for simultaneous and mapping. CASPR is employed for efficient and flexible k‐space sampling at isotropic resolution during free breathing. The imaging pipeline includes subspace reconstruction, water‐fat separation, and ‐specific dictionary matching. The proposed method was validated in a water‐fat relaxometry phantom using spin echo‐based reference techniques and was compared with MOLLI and GRASE mapping in 10 volunteers. The method's flexibility was assessed at isotropic resolutions of 2.5, 3, and 3.5 mm, with corresponding scan times of 7:19, 5:23, and 3:52 min. Additionally, the method was applied to 9 oncological patients with abdominal pathologies. Results Phantom experiments demonstrated good agreement between the proposed method and spin echo‐based reference techniques across a wide range of and values. The volunteer study assessed in vivo quantification performance and demonstrated the flexibility of the proposed method at different spatial resolutions. The 3 mm method was successively performed in patients with abdominal pathologies, whereby lesions with diameters below 1 cm could be assessed. Conclusion The proposed Look‐Locker‐based method using CASPR enables efficient, flexible, and simultaneous and mapping at isotropic resolution in a fixed scan time during free breathing.