Wang Fu-Nien, Huang Teng-Yi, Lin Fa-Hsuan, Chuang Tzu-Chao, Chen Nan-Kuei, Chung Hsiao-Wen, Chen Cheng-Yu, Kwong Kenneth K
Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
Magn Reson Med. 2005 Nov;54(5):1232-40. doi: 10.1002/mrm.20677.
A technique suitable for diffusion tensor imaging (DTI) at high field strengths is presented in this work. The method is based on a periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) k-space trajectory using EPI as the signal readout module, and hence is dubbed PROPELLER EPI. The implementation of PROPELLER EPI included a series of correction schemes to reduce possible errors associated with the intrinsically higher sensitivity of EPI to off-resonance effects. Experimental results on a 3.0 Tesla MR system showed that the PROPELLER EPI images exhibit substantially reduced geometric distortions compared with single-shot EPI, at a much lower RF specific absorption rate (SAR) than the original version of the PROPELLER fast spin-echo (FSE) technique. For DTI, the self-navigated phase-correction capability of the PROPELLER EPI sequence was shown to be effective for in vivo imaging. A higher signal-to-noise ratio (SNR) compared to single-shot EPI at an identical total scan time was achieved, which is advantageous for routine DTI applications in clinical practice.
本文介绍了一种适用于高场强扩散张量成像（DTI）的技术。该方法基于使用EPI作为信号读出模块的周期性旋转重叠平行线增强重建（PROPELLER）k空间轨迹，因此被称为PROPELLER EPI。PROPELLER EPI的实现包括一系列校正方案，以减少与EPI对失谐效应固有更高敏感性相关的可能误差。在3.0特斯拉MR系统上的实验结果表明，与单次激发EPI相比，PROPELLER EPI图像的几何失真显著降低，且射频比吸收率（SAR）远低于原始版本的PROPELLER快速自旋回波（FSE）技术。对于DTI，PROPELLER EPI序列的自导航相位校正能力在体内成像中被证明是有效的。在相同的总扫描时间内，与单次激发EPI相比，实现了更高的信噪比（SNR），这对于临床实践中的常规DTI应用是有利的。
