Respiratory‐Resolved Isotropic 3D T 1 Mapping of the Carotid Vessel Wall With B 1 + Correction ( CARISMAT1C )

ABSTRACT Purpose To develop, optimize, and characterize a respiratory motion‐resolved free‐running isotropic 3D carotid vessel wall T 1 mapping technique named CARISMAT1C. Methods An inversion‐recovery gradient‐echo free‐running pulse sequence with interleaved double flip‐angle (2FA) was implemented, and an extended‐phase‐graph dictionary was used to map the T 1 relaxation time. In a phantom, the T 1 accuracy was compared to that of a single‐flip‐angle (1FA) variant, the inversion‐recovery spin‐echo reference, and clinical routine MOLLI, while the T 1 precision of several phyllotaxis‐based radial trajectories was compared. The most precise sequence was used in 11 healthy volunteers (25 ± 3Y, 3F). A synthetic 3D gray‐blood image was reconstructed from the source images and used to delineate the internal, external, and common carotid arteries. T 1 values across artery sections were compared to those of MOLLI. Results In the phantom, the 2FA variant had higher T 1 agreement with the IR‐SE reference than 1FA or MOLLI. The top‐to‐bottom phyllotaxis trajectory with golden‐step shuffling was the most precise and was retained for in vivo scans. End‐expiratory carotid vessel wall T 1 values (1185 ± 42 ms) were similar to those obtained with MOLLI (1162 ± 84 ms, p = 0.37) and showed less intersubject variability and high interscan repeatability. No significant differences were found across arterial segments in the vessel wall T 1 values. Conclusion CARISMAT1C had high T 1 accuracy in phantoms and high T 1 precision in vivo in different sections of the carotid artery tree.