Anisotropic Twisted Projection Sodium MRI of Articular Cartilage in the Human Knee

Alexander Watts¹, Robert Stobbe¹, Christian Beaulieu¹

3D projection imaging has potential benefits in sodium MRI due to ultra-low echo times, but the spherical sampling of k-space leads to isotropic voxels which may not be ideal for imaging thin structures such as cartilage in the knee. Oblate-spheroidal twisted projection imaging, which yields anisotropic voxels, was compared to isotropic acquisition; both projection acquisitions had equal voxel volume (2.56 mm3), twist, readout length, and scan time. The anisotropic projection acquisition had better effective in-plane resolution in a saline resolution phantom and yielded sharper, higher quality sagittal sodium images of human knee cartilage (n=3) in 9 min at 4.7T.