Accelerated motion‐robust abdominal 3D T1ρ mapping using diamond radial sampling

Abstract Purpose To develop and validate a fast, motion‐robust, free‐breathing abdominal 3D T1ρ mapping method by combining variable‐density diamond radial k‐space sampling with fast‐MAPSS (magnetization‐prepared angle‐modulated partitioned‐k‐space spoiled gradient‐echo snapshots). Methods 3D MAPSS T1ρ imaging was performed at 3T using five spin‐lock time (TSL) pairs in phantom scans and three TSL pairs in nine healthy volunteers. Phantom experiments compared Cartesian sampling (reference) with stack‐of‐stars and diamond radial sampling. Volunteer scans utilized stack‐of‐stars and diamond sampling. T1ρ values were calculated using mono‐exponential fitting with MAPSS (five or three TSL pairs) and fast‐MAPSS (three TSLs). These values were compared across sampling methods and T1ρ techniques in phantom and in vivo for the liver, pancreas, and muscles. Results Diamond sampling achieved a 2.2‐fold acceleration compared to stack‐of‐stars. In phantom experiments, mean T1ρ differences from reference Cartesian MAPSS were −1.93% for stack‐of‐stars, and −0.09% for diamond sampling. Fast‐MAPSS with three TSLs resulted in differences of 0.54% (stack‐of‐stars) and 1.45% (diamond). In volunteers, a strong correlation ( R 2 ≥ 0.88) was observed between diamond and stack‐of‐stars MAPSS, and between MAPSS and fast‐MAPSS for both sampling methods. Bland–Altman analysis revealed minimal biases (<1.5 ms) between the methods. Paired t‐tests indicated no significant T1ρ differences between MAPSS and fast‐MAPSS or between sampling methods in volunteers. Conclusion Fast‐MAPSS with diamond radial k‐space sampling enables clinically feasible, motion‐robust, free‐breathing 3D T1ρ mapping of the abdomen with reduced scan time and quantification accuracy comparable to standard methods.