Fast multi-parametric imaging in abdomen by corrected dual-flip angle sequence with interleaved echo acquisition.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Quantitative Imaging

Background:

• Accurate quantification of liver fat (proton density fat fraction - PDFF) and T1 relaxation times (T1w) is crucial for diagnosing and managing hepatic steatosis.
• Simultaneous measurement of these parameters in a single breath-hold remains a challenge in abdominal MRI.

Purpose of the Study:

• To develop and validate a novel MRI technique for simultaneous T1-weighted (T1w) imaging, proton density fat fraction (PDFF) mapping, and T2* quantification in the abdomen.
• To achieve this multi-parametric quantification within a single breath-hold for improved patient comfort and reduced motion artifacts.

Main Methods:

• An optimized multi-echo gradient echo (GRE) sequence with dual flip-angle acquisition was employed.
• A novel fat-water separation method (SORT) was introduced, leveraging T1 differences to resolve ambiguity.
• T2* mapping was used to correct for magnetic field inhomogeneity in T1w relaxometry.
• 2D parallel imaging was incorporated to enable single breath-hold acquisition.

Main Results:

• Phantom studies demonstrated high accuracy and consistency with reference methods for PDFF (R²=0.993), T1w (R²=0.999), and T2* (R²=0.949) quantification.
• Volunteer studies showed robust fat-water separation without swaps, enabling reliable simultaneous T1w/PDFF/T2* mapping of the entire liver.
• The entire process was successfully completed within a single breath-hold.

Conclusions:

• The proposed MRI technique accurately and simultaneously quantifies T1w, PDFF, and T2* in the liver within a single breath-hold.
• This quantitative imaging approach offers a valuable tool for the assessment and management of patients with hepatic steatosis.