A NEW PROPELLER EPI DESIGN USING SHORT AXIS READOUTS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。简介EPI存在各种伪像，如几何失真、奈奎斯特重影、T2*模糊、麦克斯韦效应和涡流(尤其是DW-EPI)。这些伪影的大小与沿相位编码方向的k空间遍历的速度成反比。伪带宽)，它由两个因素决定：a)EPI读出序列中两个连续回波之间的时间和b)相位视场(FOV材料和方法)，使用配备50mT/m梯度的1.5T GE Excite系统进行实验。将我们提出的SAP-EPI与LAP-EPI w.r.t.由于奈奎斯特重影和敏感度造成的模糊。为了比较LAP-EPI和SAP-EPI之间单个叶片的重影水平，使用了一个直径为10厘米的小圆柱体模，视场为24？24厘米。使用从0到180°的25个刀片，获得的分辨率分别为256？32(LAP-EPI)和32？256(SAP-EPI)。使用常规的SSEPI、LAP-EPI和SAP-EPI在志愿者身上采集图像，具有相同的参数和256？256的目标分辨率。参考文献1.喉管JG。螺旋桨磁共振运动校正：在头部运动和自由呼吸心脏成像中的应用。《医学评论》1999；42(5)：963-969。2.王凤宁、黄泰、林芳华、庄铁柱、陈力克、钟旭伟、陈彩云、邝其志。螺旋桨EPI：一种适用于高场强、减少几何失真的扩散张量成像的磁共振成像技术。《医学评论》2005；54(5)：1232-1240。3.用圆对称相控阵射频线圈实现螺旋桨EPI的传感平行成像。2004年；京都。P。4.《福布斯》KP、派克JG、Bird CR、Heiserman JE。螺旋桨核磁共振：一种量化和补偿头部运动的新技术的临床测试。《磁共振成像杂志》2001；14(3)：215-222。5.Grive SM，Blamire AM，Styles P.读出对EPI中的梯度交叉项进行相位编码所引起的奈奎斯特重影的消除。《医学评论》2002；47(2)：337-343。感谢这项工作得到了美国国立卫生研究院(1R01EB002771)、斯坦福高级磁共振技术中心(P41RR09784)、卢卡斯基金会和橡树基金会的部分支持。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction EPI suffers from various artifacts such as geometric distortions, Nyquist ghosting, T2* blurring, Maxwell effects and eddy currents (especially for DW-EPI). The magnitude of these artifacts is inversely scaled by the speed of k-space traversal along the phase encoding direction (a.k.a. pseudo bandwidth), which is determined by two factors: a) the time between two consecutive echoes in the EPI readout train and b) the phase field-of-view (FOV Materials and methods A 1.5T GE Excite system equipped with 50 mT/m gradients was used for the experiments. Our proposed SAP-EPI was compared with LAP-EPI w.r.t. blurring due to Nyquist ghosting and susceptibility. To compare the ghosting levels for the individual blades between LAP-EPI and SAP-EPI, a small cylindrical phantom measuring 10 cm in diameter was used with a FOV of 24¿24 cm. The acquired resolutions were 256¿32 (LAP-EPI) and 32¿256 (SAP-EPI) using 25 blades swept from 0 to 180¿. Images were also acquired on a volunteer using conventional ssEPI, LAP-EPI and SAP-EPI, with the same parameters and target resolution of 256¿256. References 1. Pipe JG. Motion correction with PROPELLER MRI: application to head motion and free-breathing cardiac imaging. Magn Reson Med 1999;42(5):963-969. 2. Wang FN, Huang TY, Lin FH, Chuang TC, Chen NK, Chung HW, Chen CY, Kwong KK. PROPELLER EPI: An MRI technique suitable for diffusion tensor imaging at high field strength with reduced geometric distortions. Magn Reson Med 2005;54(5):1232-1240. 3. Chuang TC, Huang TY, Lin FH, Wang FN, Chung HW, Chen CY, Kwong K. Propeller EPI with SENSE parallel imaging using a circularly symmetric phase array RF coil. 2004; Kyoto. p 535. 4. Forbes KP, Pipe JG, Bird CR, Heiserman JE. PROPELLER MRI: clinical testing of a novel technique for quantification and compensation of head motion. J Magn Reson Imaging 2001;14(3):215-222. 5. Grieve SM, Blamire AM, Styles P. Elimination of Nyquist ghosting caused by read-out to phase-encode gradient cross-terms in EPI. Magn Reson Med 2002;47(2):337-343. Acknowledgements This work was supported in part by the NIH (1R01EB002771), the Center of Advanced MR Technology at Stanford (P41RR09784), Lucas Foundation, and Oak Foundation.