title: Results for diffusion-weighted imaging with a fourth-channel gradient insert.
abstract: Diffusion-weighted imaging suffers from motion artifacts and relatively low signal quality due to the long echo times required to permit the diffusion encoding. We investigated the inclusion of a noncylindrical fourth gradient coil, dedicated entirely to diffusion encoding, into the imaging system. Standard three-axis whole body gradients were used during image acquisition, but we designed and constructed an insert coil to perform diffusion encodings. We imaged three phantoms on a 3-T system with a range of diffusion coefficients. Using the insert gradient, we were able to encode b values of greater than 1300 s/mm(2) with an echo time of just 83 ms. Images obtained using the insert gradient had higher signal to noise ratios than those obtained using the whole body gradient: at 500 s/mm(2) there was a 18% improvement in signal to noise ratio, at 1000 s/mm(2) there was a 39% improvement in signal to noise ratio, and at 1350 s/mm(2) there was a 56% improvement in signal to noise ratio. Using the insert gradient, we were capable of doing diffusion encoding at high b values by using relatively short echo times.
authors: Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada. rfeldman@ualberta.ca
authors: Rebecca E
authors: RE
authors: Feldman
authors: Timothy J
authors: TJ
authors: Scholl
authors: Jamu K
authors: JK
authors: Alford
authors: William B
authors: WB
authors: Handler
authors: Chad T
authors: CT
authors: Harris
authors: Blaine A
authors: BA
authors: Chronik