Rotated stack-of-spirals partial acquisition for rapid volumetric parallel MRI

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Radiology

Background:

• Parallel imaging techniques in MRI are crucial for accelerating data acquisition.
• Undersampling in parallel imaging often leads to aliasing artifacts, compromising image quality.
• Volumetric imaging requires efficient sampling strategies to cover large anatomical regions rapidly.

Purpose of the Study:

• To introduce a novel volumetric sampling method utilizing rotated spiral interleaves within a stack of spirals (SOSP) trajectory.
• To reduce aliasing artifacts in undersampled SOSP acquisitions using parallel imaging with volumetric receiver arrays.
• To enhance the efficiency and applicability of volumetric MRI scans.

Main Methods:

• A modified SOSP trajectory was implemented by consecutively rotating spiral interleaves in each phase-encoding plane.
• High reduction factors were achieved using a volumetric multireceiver array.
• Phantom and in vivo brain images were acquired at 3T with a 32-channel coil at 1x1x2 mm(3) resolution.
• Image reconstruction involved a reduction factor of 16, with comparisons of aliasing artifacts and geometry factor (g-factor).

Main Results:

• The rotated SOSP acquisition demonstrated reduced aliasing artifacts compared to non-rotated SOSP.
• Lower geometry factor (g-factor) values were observed with the rotated SOSP method.
• Effective image reconstruction was achieved at a reduction factor of 16 for both phantom and in vivo brain data.

Conclusions:

• The proposed rotated SOSP sampling method significantly reduces aliasing artifacts in undersampled volumetric MRI.
• This technique maximizes the encoding power of volumetric receiver arrays in parallel imaging.
• The method is highly efficient and applicable to rapid volumetric scanning, including susceptibility-weighted imaging and functional MRI.