EDDY CURRENT INDUCED IMAGE WARPING IN DIFFUSION WEIGHTED EPI

扩散加权 EPI 中涡流引起的图像扭曲

• 批准号: 6123022
• 负责人: ALEXANDER D CRESPIGNY
• 金额: --
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6123022
• 关键词: Mammalia; bioimaging /biomedical imaging; biomedical resource; magnetic resonance imaging; technology /technique

Introduction: MRI detection of subarachnoid hemorrhage (SAH) is an important but controversial tool for monitoring acute stroke patients. Recent publications favorably compare FLAIR (fluid attenuated inversion recovery) MRI to computed tomography (CT) for the detection of acute SAH. However, the source of this MR image contrast is not well understood. The purpose of this study was to investigate the source of the SAH contrast by comparing FLAIR images of various blood/cerebrospinal fluid (CSF) mixtures with brain. Methods: Fresh CSF was obtained from the cisterna magna and arterial blood was obtained from the femoral artery of rats. Five sample tubes were prepared: 1) heparinized blood, 2) 50/50% nonheparinized blood in phosphor buffered saline (PBS), 3) 50/50% nonheparinized blood in CSF, 4) nonheparinized blood, and 5) pure CSF. After 4 hours of settling time, the tubes were positioned next to the head of a rat and fast spin-echo FLAIR images were acquired of in-vivo brain and the sample tubes simultaneously using a 2 T GE CSI spectrometer. Transverse (T2) and longitudinal (T1) relaxation times were also measured. Results and Conclusion: All blood clots were isointense to brain on the FLAIR images. The process of clotting causes shortening of T1 and T2 to values similar to those of brain which results in little contrast on FLAIR between clots in CSF and brain. In contrast, the cells which settled in the heparinized blood were ~50% brighter than brain on FLAIR. In addition, each of the tubes containing a clot showed a thin layer of settled blood cells which was also hyperintense. T2 values for non-clotted cells were higher than for brain but less than for CSF. Hyperintensities on FLAIR images of SAH are probably due to the unclotted portion of subarachnoid blood and are best seen using long echo times.

简介：蛛网膜下腔出血（SAH）的MRI检测是 一种重要但有争议的监测急性中风的工具， 患者 最近的出版物有利地比较FLAIR（流体 衰减反转恢复）MRI到计算机断层扫描（CT）， 检测急性SAH。 然而，这种MR图像对比度的来源 并没有得到很好的理解。 本研究的目的是调查 SAH对比度的来源，通过比较不同的FLAIR图像 血液/脑脊液（CSF）与脑的混合物。 方法：新鲜 从小脑延髓池获得CSF，并采集动脉血。 从大鼠的股动脉获得。 五个样品管， 制备：1）肝素化血液，2）50/50%非肝素化血液， 磷酸盐缓冲盐水（PBS），3）CSF中的50/50%非肝素化血液， 4)非肝素化血液和5）纯CSF。 沉淀4小时后 一次，将管定位在大鼠的头部旁边，并快速放置。 获取活体脑和样本的自旋回波FLAIR图像 管同时使用2 T GE CSI光谱仪。 横向（T2） 和纵向（T1）弛豫时间也被测量。 结果 结论：所有血凝块在FLAIR序列上均与脑实质呈等信号 图像. 凝血过程导致T1和T2缩短， 值与大脑的值相似，这导致在 CSF和大脑中凝块之间的FLAIR。 相反， 在肝素化血液中的沉淀比大脑亮约50%， FLAIR。 此外，每个含有凝块的试管都显示出一个薄的 一层沉淀的血细胞，也是高信号。 T2值 对于非凝块细胞，高于大脑，但低于 脑脊液。 SAH的FLAIR图像上的高信号可能是由于 蛛网膜下腔血液未凝结的部分，最好使用长 回声时报。