Improved High-Resolution SNAILS DTI with A Spiral-in Navigator
Moseley M, Bammer R, Liu C
Variable density (VD) spiral has been applied in SNAILS for the acquisition of high-resolution diffusion weighted images. By oversampling the center of k-space, SNAILS provides the capability to navigate the motion-induced phase errors. However oversampling increases off-resonance blurring. A method is proposed to improve SNAILS by applying a spiral-in phase navigator. This extra navigator reduces the oversampling factor of the VD spiral, while maintaining a reasonable high SNR to compensate residual artifacts. In vivo high-resolution DTI is demonstrated using two VD spiral pitch factors. The navigator enables a smaller pitch factor and improves the image SNR and contrast.