DIFFUSION TENSOR IMAGING AT HIGH FIELDS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this research continues to refine and improve the methodology of diffusion tensor imaging (DTI) at very high fields (3T and 7T) for the investigators and collaborators on the P41 RR09784 "Center for Advanced MR Technology at Stanford" effort. Preliminary studies from a variety of studies suggest that DTI may predict the cognitive and motor performances of a patient from scans requiring several minutes. Diffusion is measured along at least six non-collinear directions. For each gradient direction, typically four images were acquired and averaged. Two images with no diffusion weighting (b = 0s/mm2) are acquired and a set of Inversion Recovery (IR) images for CSF nulling are acquired with b = 0s/mm2; these images were used to unwarp the diffusion weighted images, which resulted in a more robust unwarping than using the non-IR b=0 images. The development of SENSE and more robust parallel imaging sequences and post-processing methods has accelerated the use of high fields for diffusion studies. Issues regarding the opimal protocol and set of sequence parameters needed for various diffusion studies are under investigation, which includes more rapid protocols for the assessment of stroke and more high resolution protocols for diffusion tensor imaging of white matter tracts. The effort is being translated from 3T to newer field studies at 7T.