A comparative study of acquisition schemes for diffusion tensor imaging using MRI

This study has investigated the effects of the selection of the diffusion-w eighted (DW) gradient directions on the precision of a diffusion tensor ima ging (DTI) experiment. The theoretical analysis provided a quantitative fra mework in which the noise performance of DTI schemes could be assessed obje ctively and for the development of novel DTI schemes, which employ multiple DW gradient directions. This generic framework was first applied to the ex amination of two commonly used DTI schemes, which employed 6 DW gradient di rections and hitherto were used indiscriminately under the sole condition o f noncollinearity. It was then used to design and assess a novel 12-DW-grad ient-direction DTI protocol, which employed the same total number of DW acq uisitions as the two conventional schemes (12), This theoretical investigat ion was then corroborated using rigorous simulation and DTI experiments on both an isotropic phantom and a healthy human brain. Both the theoretical a nd the experimental analysis demonstrated that the two conventional schemes showed a significantly different noise performance and that use of the new multiple-DW-gradient-direction scheme clearly improved the precision of th e DTI measurements. (C) 1999 Academic Press.