Efficient T₂ mapping with blip-up/down EPI and gSlider-SMS (T₂ -BUDA-gSlider)

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Quantitative MRI
• Neuroimaging

Background:

• Accurate T2 mapping is crucial for various clinical and neuroscience applications.
• Existing methods often face limitations in speed, resolution, or geometric fidelity.

Purpose of the Study:

• To develop a rapid method for acquiring high isotropic-resolution T2 maps with whole-brain coverage and high geometric fidelity.
• To address limitations of current T2 mapping techniques.

Main Methods:

• Proposed a T2 blip-up/down EPI acquisition with generalized slice-dithered enhanced resolution (T2-BUDA-gSlider).
• Employed RF-encoded multi-slab spin-echo (SE) EPI with multiple TEs for SNR efficiency and reduced TR.
• Integrated an estimated field map into joint multi-shot EPI reconstruction with a structured low rank constraint for distortion-free reconstruction.
• Utilized a Bloch simulated subspace model within gSlider reconstruction for T2 quantification.

Main Results:

• In vivo results showed T2 values consistent with gold standard spin-echo acquisition.
• The proposed method effectively mitigated distortions from off-resonance and eddy current effects compared to reference 3D fast spin echo (FSE) images.

Conclusions:

• BUDA-gSlider SE-EPI acquisition and gSlider-subspace joint reconstruction enable distortion-free whole-brain T2 mapping.
• Achieved ~1 mm³ isotropic resolution T2 maps in 2 minutes.
• This technique offers significant benefits for clinical and neuroscience applications.