Free‐breathing 3D cardiac extracellular volume (ECV) mapping using a linear tangent space alignment (LTSA) model

Abstract Purpose To develop a new method for free‐breathing 3D extracellular volume (ECV) mapping of the whole heart at 3 T. Methods A free‐breathing 3D cardiac ECV mapping method was developed at 3 T. T 1 mapping was performed before and after contrast agent injection using a free‐breathing electrocardiogram‐gated inversion recovery sequence with spoiled gradient echo readout. A linear tangent space alignment model‐based method was used to reconstruct high‐frame‐rate dynamic images from (k,t)‐space data sparsely sampled along a random stack‐of‐stars trajectory. Joint T 1 and transmit B 1 estimation were performed voxel‐by‐voxel for pre‐ and post‐contrast T 1 mapping. To account for the time‐varying T 1 after contrast agent injection, a linearly time‐varying T 1 model was introduced for post‐contrast T 1 mapping. ECV maps were generated by aligning pre‐ and post‐contrast T 1 maps through affine transformation. Results The feasibility of the proposed method was demonstrated using in vivo studies with six healthy volunteers at 3 T. We obtained 3D ECV maps at a spatial resolution of 1.9 × 1.9 × 4.5 mm 3 and a FOV of 308 × 308 × 144 mm 3 , with a scan time of 10.1 ± 1.4 and 10.6 ± 1.6 min before and after contrast agent injection, respectively. The ECV maps and the pre‐ and post‐contrast T 1 maps obtained by the proposed method were in good agreement with the 2D MOLLI method both qualitatively and quantitatively. Conclusion The proposed method allows for free‐breathing 3D ECV mapping of the whole heart within a practically feasible imaging time. The estimated ECV values from the proposed method were comparable to those from the existing method.