Rapid fat-water separated T₁ mapping using a single-shot radial inversion-recovery spoiled gradient recalled pulse...

Area of Science:

• Magnetic Resonance Imaging
• Medical Physics
• Biomedical Engineering

Background:

• T1 mapping is crucial in clinical and research settings.
• Existing T1 mapping techniques face limitations in spatial resolution, contrast, and slice coverage due to scan time constraints.
• High fat concentrations introduce significant errors in conventional Look-Locker T1 methods.

Purpose of the Study:

• To develop and validate a novel dual-echo 2D radial inversion-recovery T1 (DEradIR-T1) technique for rapid fat-water separated T1 mapping.
• To assess the accuracy and performance of DEradIR-T1 in phantoms and in vivo, particularly in the presence of fat.
• To investigate the impact of intravoxel fat on T1 measurements and evaluate the efficacy of DEradIR-T1 in mitigating these effects.

Main Methods:

• Development of a dual-echo 2D radial inversion-recovery T1 (DEradIR-T1) sequence.
• Simulations to analyze composite (fat + water) and water-only T1 under varying echo times (TE) and fat concentrations.
• Validation using standardized phantoms (NIST, Calimetrix fat-water) with an inversion-recovery spin echo (IR-SE) sequence as reference.
• In vivo assessment in 5 volunteers and 28 patients using a 3T MRI scanner, comparing DEradIR-T1 with modified Look-Locker inversion recovery (MOLLI).
• Statistical analysis including Bland-Altman analysis and paired t-tests.

Main Results:

• Simulations accurately predicted in vivo T1 behavior under different fat concentrations and echo times.
• DEradIR-T1 demonstrated high correlation with reference methods in phantoms (Pcomp = 0.97 for NIST, Pwater = 0.56 for Calimetrix).
• In vivo T1 values obtained with DEradIR-T1 showed strong agreement with MOLLI.
• Intravoxel fat was confirmed to have a variable, echo-time-dependent effect on T1 values.

Conclusions:

• The proposed DEradIR-T1 technique enables fast, fat-water separated T1 mapping.
• DEradIR-T1 effectively mitigates the confounding effects of intravoxel fat on T1 measurements.
• This technique holds promise for improving the accuracy and reliability of T1 mapping in diverse clinical and research applications.