Abdominal simultaneous 3D water T₁ and T₂ mapping using a free-breathing Cartesian acquisition with spiral profile...

Area of Science:

• Magnetic Resonance Imaging
• Medical Physics
• Radiology

Background:

• Accurate water T1 and T2 mapping is crucial for abdominal imaging.
• Current methods often require breath-holding or lack isotropic resolution.
• Developing efficient, free-breathing techniques is essential for patient comfort and diagnostic quality.

Purpose of the Study:

• To develop and validate a novel method for simultaneous 3D water T1 and T2 mapping in the abdomen.
• To achieve isotropic resolution using a free-breathing Cartesian acquisition with spiral profile ordering (CASPR) at 3 Tesla.
• To assess the method's performance in phantoms, volunteers, and patients with abdominal pathologies.

Main Methods:

• A Look-Locker scheme combined with a modified BIR-4 adiabatic preparation pulse for simultaneous water T1 and T2 mapping.
• Cartesian acquisition with spiral profile ordering (CASPR) for efficient k-space sampling at isotropic resolution during free breathing.
• Subspace reconstruction, water-fat separation, and B0-specific dictionary matching for image processing.

Main Results:

• Phantom experiments showed good agreement with spin echo reference techniques for water T1 and T2 values.
• Volunteer studies confirmed in vivo quantification and demonstrated flexibility across different isotropic resolutions (2.5, 3, and 3.5 mm).
• The 3 mm method successfully imaged abdominal pathologies in patients, identifying lesions smaller than 1 cm.

Conclusions:

• The proposed Look-Locker-based method with CASPR enables efficient, flexible, and simultaneous 3D water T1 and T2 mapping at isotropic resolution.
• The technique operates within a fixed scan time during free breathing, enhancing patient tolerance.
• This method offers a promising advancement for abdominal MRI, particularly for evaluating pathologies.