Influence of SENSE on image properties in high‐resolution single‐shot echo‐planar DTI

Limited spatial resolution is a key obstacle to the study of brain white matter structure with diffusion tensor imaging (DTI). In its frequent implementation with single‐excitation spin‐echo echo‐planar sequences, DTI's ability to resolve small structures is strongly restricted by T2 and T  2* decay, B0 inhomogeneity, and limited signal‐to‐noise ratio (SNR). In this work the influence of sensitivity encoding (SENSE) on diffusion‐weighted (DW) image properties is investigated. Computer simulations showed that the PSF becomes narrower with increasing SENSE reduction factors, R, enhancing the intrinsic resolution. After a brief theoretical discussion, we describe the estimation of SNR on a pixel‐by‐pixel basis as a function of R. The mean image SNR behavior is manifold: SENSE is capable of increasing SNR efficiency by reducing the echo time (TE). Each SNR(R) curve reveals a maximum that depends on the amount of partial Fourier encoding used. The overall best SNR efficiency for an eight‐element head coil array and a b‐factor of 1000 s/mm2 is achieved at R = 2.1 and partial Fourier encoding of 60%. In vivo tensor maps of volunteers and a patient, with an in‐plane resolution of 0.78 × 0.78 mm2, are also presented to demonstrate the practical implementation of the parallel approach. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.