Zhang Ke, Sturm Volker J, Buschle Lukas R, Hahn Artur, Yun Seong Dae, Jon Shah N, Bendszus Martin, Heiland Sabine, Schlemmer Heinz-Peter, Ziener Christian H, Kurz Felix T
Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany; Department of Radiology, German Cancer Research Center, Heidelberg, Germany.
Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany.
Magn Reson Imaging. 2019 Apr;57:359-367. doi: 10.1016/j.mri.2018.11.018. Epub 2018 Nov 27.
A 2D gradient-echo EPI is commonly employed for arterial spin labeling (ASL) readout to achieve fast whole brain coverage measurements. However, such a readout suffers from susceptibility artifacts induced by magnetic field inhomogeneities. To reduce these susceptibility effects, single-shot spin-echo EPI was proposed to be used for acquisitions in continuous ASL (CASL). To minimize functional and physiological variations, a gradient-echo (GE)/spin-echo (SE) dual-echo EPI readout of the CASL sequence is needed for a comparison between GE- and SE-based determination of cerebral blood flow (CBF). In this study, we employed a simultaneous GE/SE multiband EPI as the readout of a pseudo-CASL (pCASL) sequence. Motor cortex activations derived from a finger-tapping task and functional networks from resting state fMRI were compared for both GE and SE contrasts. Direct comparison of SE and GE contrasts revealed that GE ASL provides an improved sensitivity of functional activity in finger-tapping and in resting-state imaging. SE ASL, on the other hand, suffered less from susceptibility artifacts induced by magnetic field inhomogeneities and pulsatile flow artifacts.
二维梯度回波平面回波成像（EPI）通常用于动脉自旋标记（ASL）读出，以实现快速全脑覆盖测量。然而，这种读出会受到磁场不均匀性引起的磁化率伪影的影响。为了减少这些磁化率效应，有人提出使用单次自旋回波EPI进行连续动脉自旋标记（CASL）采集。为了最小化功能和生理变化，需要使用CASL序列的梯度回波（GE）/自旋回波（SE）双回波EPI读出，以便比较基于GE和SE的脑血流量（CBF）测定。在本研究中，我们采用同时GE/SE多波段EPI作为伪连续动脉自旋标记（pCASL）序列的读出。比较了GE和SE对比下，由手指轻敲任务得出的运动皮层激活情况以及静息态功能磁共振成像的功能网络。SE和GE对比的直接比较表明，GE ASL在手指轻敲和静息态成像中提供了更高的功能活动灵敏度。另一方面，SE ASL受磁场不均匀性引起的磁化率伪影和搏动血流伪影的影响较小。
