Fast susceptibility-weighted imaging with three-dimensional short-axis propeller (SAP)-echo-planar imaging

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)

Background:

• Susceptibility-weighted imaging (SWI) is crucial in neuroimaging but faces challenges with long scan times for 3D gradient recalled echo (GRE) and motion artifacts in faster 3D interleaved echo-planar imaging (iEPI).
• A novel 3D short-axis propeller echo-planar imaging (SAP-EPI) trajectory is proposed to address these limitations.

Purpose of the Study:

• To introduce and evaluate the 3D SAP-EPI technique as a faster, motion-correctable method for SWI.
• To compare the performance of 3D SAP-EPI against conventional 3D GRE and 3D iEPI SWI techniques.

Main Methods:

• Experiments were performed on a 3T MRI system using 3D SAP-EPI, 3D iEPI, and 3D GRE SWI sequences on volunteers.
• Controlled motion experiments were conducted to assess the motion-correction capabilities of 3D SAP-EPI.
• 3D SAP-EPI SWI was also acquired in pediatric patients as a potential clinical alternative.

Main Results:

• 3D GRE achieved higher resolution (0.47 × 0.94 × 2 mm) with a 5-minute scan time.
• 3D SAP-EPI provided comparable resolution (0.94 × 0.94 × 2 mm) in a significantly shorter scan time (1:52 min) with doubled brain coverage.
• SAP-EPI demonstrated effective motion correction and resilience to undersampling artifacts.

Conclusions:

• Despite some geometric distortion, 3D SAP-EPI offers a substantial reduction in scan time and robust motion correction.
• SAP-EPI presents a promising alternative to GRE and iEPI for SWI, particularly beneficial for uncooperative subjects like pediatric patients.