Results for diffusion‐weighted imaging with a fourth‐channel gradient insert
Source InformationDecember 2011, Volume66(Issue6) Page1798To1808
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. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.