Scan time reduction for readout‐segmented EPI using simultaneous multislice acceleration: Diffusion‐weighted imaging at 3 and 7 Tesla

Abstract

PurposeReadout‐segmented echo‐planar imaging (rs‐EPI) can provide high quality diffusion data because it is less prone to distortion and blurring artifacts than single‐shot echo‐planar imaging (ss‐EPI), particularly at higher resolution and higher field. Readout segmentation allows shorter echo‐spacing and echo train duration, resulting in reduced image distortion and blurring, respectively, in the phase‐encoding direction. However, these benefits come at the expense of longer scan times because the segments are acquired in multiple repetitions times (TRs). This study shortened rs‐EPI scan times by reducing the TR duration with simultaneous multislice acceleration.MethodsThe blipped‐CAIPI method for slice acceleration with reduced g‐factor SNR loss was incorporated into the diffusion‐weighted rs‐EPI sequence. The rs‐ and ss‐EPI sequences were compared at a range of resolutions at both 3 and 7 Tesla in terms of image fidelity and diffusion postprocessing results.ResultsSlice‐accelerated clinically useful trace‐weighted images and tractography results are presented. Tractography analysis showed that the reduced artifacts in rs‐EPI allowed better discrimination of tracts than ss‐EPI.ConclusionSlice acceleration reduces rs‐EPI scan times providing a practical alternative to diffusion‐weighted ss‐EPI with reduced distortion and high resolution. Magn Reson Med 74:136–149, 2015. © 2014 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Human brain diffusion tensor imaging at submillimeter isotropic resolution on a 3 Tesla clinical MRI scanner

“…It has been shown previously that this DWI sequence, with phase-encoding gradients applied along the slice-direction for 3D encoding, has higher SNR efficiency than 2D DWI and is well suitable for high-resolution imaging (Engstrom et al, 2014; Engstrom and Skare, 2013; Frank et al, 2010; Frost et al, 2014; Frost et al, 2013; Van et al, 2014). …”

“…Although this approach is obviously not ideal, we were able to demonstrate, as a proof of concept, the feasibility of acquiring DTI data at submillimeter resolution on a clinical scanner. In order to acquire whole-brain high-resolution DTI data within a more acceptable scan time (e.g., < 30 min), one has to use an appropriate 3D imaging RF pulse (Engstrom et al, 2014; Engstrom and Skare, 2013; Frank et al, 2010; Frost et al, 2014; Frost et al, 2013; Van et al, 2014) or incorporate the recently developed approaches that minimize the through-plane banding artifacts in 3D DTI scans (Van et al, 2014). In addition, the 3D DTI scan time can be reduced by incorporating partial Fourier scans along the k z direction (e.g., acquiring only 7 out of the 12 k z planes), although at the cost of SNR.…”

Joint correction of Nyquist artifact and minuscule motion-induced aliasing artifact in interleaved diffusion weighted EPI data using a composite two-dimensional phase correction procedure

“…It has been shown in recent studies that high-resolution DWI can also be achieved with interleaved spiral imaging [23, 27, 32–35], PROPELLER [36, 37], PROPELLER-EPI [14, 15], readout-segmented EPI [17, 38, 39], steady-state free precession (SSFP) imaging [40], and radial fast spin-echo imaging [41]. …”

3D-MB-MUSE: A robust 3D multi-slab, multi-band and multi-shot reconstruction approach for ultrahigh resolution diffusion MRI

“…In recent studies (Frank et al, 2010; Engstrom et al, 2013; Engstrom et al, 2015; Frost et al, 2015), it has been shown that an additional SNR advantage can be gained over conventional 2D imaging by phase encoding the slice dimension of a thick slab with a 3D acquisition. In single-shot 3D data, motion artifacts arise from bulk through plane movement throughout the acquisition of slice-encoding planes (kz-planes) in a slab.…”