Hybrid T₂‐ and T₁‐weighted radial acquisition for free‐breathing abdominal examination

Purpose Most clinical MR examinations require acquisition of different image contrasts. For abdominal exams, the scans are conventionally performed as separate acquisitions using respiratory gating or repeated breath holding, which can be time‐inefficient and challenging for patients. Here, a hybrid imaging approach is described that creates T 2 ‐ and T 1 ‐weighted images from a single scan and allows for free‐breathing acquisition. Theory and Methods T 2 ‐weighted data is collected using 3D fast spin‐echo (FSE) acquisition with motion‐robust radial stack‐of‐stars sampling. The wait time between the FSE trains is used to acquire T 1 ‐weighted gradient‐echo (GRE) data. Improved robustness is achieved by extracting a respiratory signal from the GRE data and using it for motion‐weighted reconstruction. Results As validated in simulations and phantom scans, GRE acquisition in the wait time has minor effect on the signal strength and contrast. Volunteer scans at 1.5T showed that T 2 ‐ and T 1 ‐weighted hybrid imaging is feasible during free‐breathing. Furthermore, it has been demonstrated in a patient that hybrid imaging with T 1 ‐weighted Dixon acquisition is possible. Conclusion The described hybrid sequence enables comprehensive T 2 ‐ and T 1 ‐weighted imaging in a single scan. In addition to free‐breathing abdominal examination, it promises value for clinical applications that are frequently affected by motion artifacts.