X‐PROP: A fast and robust diffusion‐weighted propeller technique

Abstract

Diffusion‐weighted imaging (DWI) has shown great benefits in clinical MR exams. However, current DWI techniques have shortcomings of sensitivity to distortion or long scan times or combinations of the two. Diffusion‐weighted echo‐planar imaging (EPI) is fast but suffers from severe geometric distortion. Periodically rotated overlapping parallel lines with enhanced reconstruction diffusion‐weighted imaging (PROPELLER DWI) is free of geometric distortion, but the scan time is usually long and imposes high Specific Absorption Rate (SAR) especially at high fields. TurboPROP was proposed to accelerate the scan by combining signal from gradient echoes, but the off‐resonance artifacts from gradient echoes can still degrade the image quality. In this study, a new method called X‐PROP is presented. Similar to TurboPROP, it uses gradient echoes to reduce the scan time. By separating the gradient and spin echoes into individual blades and removing the off‐resonance phase, the off‐resonance artifacts in X‐PROP are minimized. Special reconstruction processes are applied on these blades to correct for the motion artifacts. In vivo results show its advantages over EPI, PROPELLER DWI, and TurboPROP techniques. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.

A robust multi-shot scan strategy for high-resolution diffusion weighted MRI enabled by multiplexed sensitivity-encoding (MUSE)

“…On the other hand, when using a higher acceleration factor, the noise is undesirably amplified in reconstructed parallel MR images. To uproot these limitations, multi-shot techniques such as interleaved EPI, interleaved spiral imaging, PROPELLER, and fast spin-echo pulse sequences with embedded or inherent low-resolution navigator echoes have been developed to address the amplified shot-to-shot motion-induced phase variations, and produce adequate high resolution DWI data (Butts et al (1996); Bammer et al (1999); Atkinson et al (2000); Pipe et al (2002); Wang et al (2005); Skare et al (2006); Atkinson et al (2006); Porter and Heidemann (2009); Li et al (2011); Jeong et al (2012)). However, navigator-echo based correction can fail if the motions differ between the navigation and the actual DWI data acquisition.…”

Steer‐PROP: a GRASE‐PROPELLER sequence with interecho steering gradient pulses

“…Finally, X‐PROP was demonstrated in a diffusion‐weighted sequence with split blades, whereas Steer‐PROP was implemented in a conventional PROPELLER sequence for both T 2 ‐weighted and diffusion‐weighted imaging. Despite the differences, both Steer‐PROP and X‐PROP can successfully separate and effectively correct for the EPI‐type and FSE‐type phase errors in a GRASE sequence, as shown in Figure and in previously published work . In this study, we explicitly separated the three types of phase errors: intrablade phase error (i.e., FSE‐type error), interblade phase error (i.e., EPI‐type error), and intershot phase error (i.e., motion‐induced error) and described the correction strategy.…”

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]. …”