1Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, Utah, USA2Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, USA3Department of Psychiatry, University of Utah, Salt Lake City, Utah, USA4Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, USA5Department of Neurosurgery, University of Utah, Salt Lake City, Utah, USA6Department of Neurology, University of Utah, Salt Lake City, Utah, USA
Checking for direct PDF access through Ovid
Purpose:High-resolution diffusion-weighted imaging (DWI) of the spinal cord (SC) is problematic because of the small cross-section of the SC and the large field inhomogeneity. Obtaining the ultrahigh-b DWI poses a further challenge. The purpose of the study was to design and validate two-dimensional (2D) single-shot diffusion-weighted stimulated echo planar imaging with reduced field of view (2D ss-DWSTEPI-rFOV) for ultrahigh-b radial DWI (UHB-rDWI) of the SC.Methods:A novel time-efficient 2D ss-DWSTEPI-rFOV sequence was developed based on the stimulated echo sequence. Reduced-phase field of view was obtained by using two slice-selective 90 Symbol radiofrequency pulses in the presence of the orthogonal slice selection gradients. The sequence was validated on a cylindrical phantom and demonstrated on SC imaging.Results:Ultrahigh-b radial diffusion-weighted (Symbol = 7300 Symbol) images of the SC with greatly reduced distortion were obtained. The exponential plus constant fitting of the diffusion-decay curve estimated the constant fraction (restricted water fraction) as 0.36 ± 0.05 in the SC white matter.Conclusion:A novel 2D ss-DWSTEPI-rFOV sequence has been designed and demonstrated for high-resolution UHB-rDWI of localized anatomic structures with significantly reduced distortion induced by nonlinear static field inhomogeneity.