Fast model-based T₂ mapping using SAR-reduced simultaneous multislice excitation.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Quantitative Imaging
• Biomedical Engineering

Background:

• Quantitative T2 mapping is crucial for various neurological applications.
• Traditional T2 mapping techniques are often time-consuming, limiting their clinical utility.
• Accelerated imaging methods are needed to improve efficiency and patient throughput.

Purpose of the Study:

• To develop a rapid, whole-brain, high-resolution T2 mapping technique.
• To achieve T2 map acquisition in under 2 minutes.
• To combine simultaneous multislice excitation, undersampling, and model-based reconstruction for accelerated T2 mapping.

Main Methods:

• A multi-echo spin-echo sequence was modified for simultaneous multislice acquisition with undersampling.
• Parallel imaging and model-based reconstruction were employed to separate slices and estimate quantitative T2 values.
• The signal model incorporated extended phase graph simulations accounting for non-ideal slice profiles and B1 inhomogeneity.
• In vivo and phantom experiments were conducted to validate accuracy and reproducibility.

Main Results:

• The accelerated technique yielded similar mean T2 values compared to conventional methods in vivo.
• Reproducibility was high, with low standard deviations between scans and across subjects.
• While combining simultaneous multislice and undersampling increased standard deviations, the overall T2 values remained comparable.

Conclusions:

• The proposed method enables fast, whole-brain T2 mapping with high resolution (0.7-mm in-plane) and low specific absorption rate.
• This technique significantly reduces acquisition time to 2 minutes.
• It holds promise for efficient quantitative MRI in clinical settings.