3D balanced SSFP UTE MRI for multiple contrasts whole brain imaging

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Biophysics

Background:

• Ultra-short transverse relaxation time (uT2) components in the brain are challenging to image.
• Existing MRI techniques may not efficiently capture these components or provide simultaneous proton density (PD) contrast.

Purpose of the Study:

• To develop a novel, high-resolution MRI sequence for imaging brain uT2 components.
• To simultaneously provide PD contrast for reference and quantification within a single acquisition.

Main Methods:

• A sequence combining balanced steady-state free precession (bSSFP) and ultrashort echo time (UTE) techniques with a 3D dual-echo rosette k-space trajectory was developed.
• Simulations were used to evaluate image contrast, and the sequence was tested on healthy volunteers and multiple sclerosis (MS) patients.
• Subtraction between two echo times (TEs) was performed to isolate uT2 signals.

Main Results:

• The sequence successfully captured uT2 signals in the first TE images and PD contrast in the second TE images.
• Subtraction images highlighted uT2 components, revealing hypointense signals in MS lesions compared to normal white matter, suggesting reduced uT2 components potentially related to myelin.
• 3D isotropic sub-millimeter resolution images were acquired in under 3 minutes.

Conclusions:

• The novel bSSFP UTE sequence enables rapid, high-resolution imaging of brain uT2 components.
• The sequence facilitates straightforward extraction of uT2 signals and PD contrast in a single scan.
• This technique shows promise for detecting myelin-related changes in neurological diseases like MS.