Magnetization-prepared GRASP MRI for rapid 3D T1 mapping and fat/water-separated T1 mapping

Li Feng; Fang Liu; Georgios Soultanidis; Chenyu Liu; Thomas Benkert; Kai Tobias Block; Zahi A Fayad; Yang Yang

doi:10.1002/mrm.28679

Magnetization-prepared GRASP MRI for rapid 3D T1 mapping and fat/water-separated T1 mapping

Magn Reson Med. 2021 Jul;86(1):97-114. doi: 10.1002/mrm.28679. Epub 2021 Feb 13.

Authors

Li Feng¹, Fang Liu², Georgios Soultanidis¹, Chenyu Liu¹, Thomas Benkert³, Kai Tobias Block^{3

4}, Zahi A Fayad¹, Yang Yang¹

Affiliations

¹ Biomedical Engineering and Imaging Institute and Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
² Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
³ MR Application Development, Siemens Healthcare GmbH, Erlangen, Germany.
⁴ Center for Advanced Imaging Innovation and Research (CAI2R), New York University School of Medicine, New York, NY, USA.

Abstract

Purpose: This study aimed to (i) develop Magnetization-Prepared Golden-angle RAdial Sparse Parallel (MP-GRASP) MRI using a stack-of-stars trajectory for rapid free-breathing T1 mapping and (ii) extend MP-GRASP to multi-echo acquisition (MP-Dixon-GRASP) for fat/water-separated (water-specific) T1 mapping.

Methods: An adiabatic non-selective 180° inversion-recovery pulse was added to a gradient-echo-based golden-angle stack-of-stars sequence for magnetization-prepared 3D single-echo or 3D multi-echo acquisition. In combination with subspace-based GRASP-Pro reconstruction, the sequence allows for standard T1 mapping (MP-GRASP) or fat/water-separated T1 mapping (MP-Dixon-GRASP), respectively. The accuracy of T1 mapping using MP-GRASP was evaluated in a phantom and volunteers (brain and liver) against clinically accepted reference methods. The repeatability of T1 estimation was also assessed in the phantom and volunteers. The performance of MP-Dixon-GRASP for water-specific T1 mapping was evaluated in a fat/water phantom and volunteers (brain and liver).

Results: ROI-based mean T1 values are correlated between the references and MP-GRASP in the phantom (R² = 1.0), brain (R² = 0.96), and liver (R² = 0.73). MP-GRASP achieved good repeatability of T1 estimation in the phantom (R² = 1.0), brain (R² = 0.99), and liver (R² = 0.82). Water-specific T1 is different from in-phase and out-of-phase composite T1 (composite T1 when fat and water signal are mixed in phase or out of phase) both in the phantom and volunteers.

Conclusion: This work demonstrated the initial performance of MP-GRASP and MP-Dixon-GRASP MRI for rapid 3D T1 mapping and 3D fat/water-separated T1 mapping in the brain (without motion) and in the liver (during free breathing). With fat/water-separated T1 estimation, MP-Dixon-GRASP could be potentially useful for imaging patients with fatty-liver diseases.

Keywords: MP-Dixon-GRASP; MP-GRASP; T1 mapping; fat/water separation; free-breathing; golden-angle radial.

MeSH terms

Humans
Imaging, Three-Dimensional
Liver
Magnetic Resonance Imaging*
Phantoms, Imaging
Respiration
Water*

Substances

Water

Abstract

MeSH terms

Substances

Grants and funding