HIGH RES DYNAMIC-SUSCEPTIBILITY CONTRAST PWI USING MULTI-ECHO PARALLEL EPI

使用多回波并行 EPI 进行高分辨率动态磁化率对比 PWI

• 批准号: 7358780
• 负责人: THIES JOCHIMSEN
• 金额: $ 1.87万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7358780
• 关键词: RES; DYNAMIC; SUSCEPTIBILITY; CONTRAST; PWI

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: In dynamic-susceptibility contrast-based MRI (DSC-MRI), time series are acquired during the first pass of an intravascular tracer from which it is possible to estimate cerebral blood volume (CBV). Pixelwise deconvolution with an arterial input function (AIF) yields maps of cerebral blood flow (CBF) and mean transit time (MTT). The benefits of a multi-echo (ME) approach for DSC-MRI are: 1) ?R2*can be measured undisturbed from T1enhancement; 2) no pre-bolus baseline signal is required; 3) automatic selection of arterial input function can be based on the first echo; 4) analysis can be limited to the first echo(es) if the dynamic range using ?R2* of all echoes is too small. In combination with parallel imaging (PI), a high spatial and temporal resolution can be achieved. PI also reduces image artifacts related to EPI. This combination of ME with PI, is termed PERMEATE. Methods and Discussion: All scans were performed on a 1.5 T Signa scanner (GE Medical Systems) with an 8-element head array. PI was performed with reduction factors R =3 and R =4. The PERMEATE parameters were: 15 slices (5-mm thick, 1-mm gap), 24-cm FOV, 96 ¿ 96 resolution, TE = 13.8, 31.6, 49.4 ms (R=3) and TE = 12.4, 27.3, 42.2, 57.1 ms (R =4), 100 repetitions with TR = 1225 ms, ¿100 kHz bandwidth, and flip angle = 70. The number of echoes equals R. A GRAPPA algorithm was used for reconstruction. A single dose of 0.1 mmol/kg Gd-DTPA was administered at 4 ml/s followed by 20-ml saline flush. Perfusion maps were calculated by a block-circulant SVD for tracer arrival timing-insensitive deconvolution (PSVD= 10%) using an automatically selected AIF from the first echo. The ratio of CBF/CBV between gray and white matter was estimated by values within a manually-drawn ROI. Gray and white matter could be well delineated in the perfusion maps. The AIFs demonstrate that the first echo has the best dynamic range for AIF selection and was used for further CBV/CBF analysis. Gray/white matter ratios of 2 subjects were in good agreement with previously reported values.

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。前言：在基于动态磁化率对比的磁共振成像(DSC-MRI)中，时间序列是在血管内示踪剂第一次通过时获得的，由此可以估计脑血流量(CBV)。使用动脉输入函数(AIF)的像素去卷积得到脑血流量(CBF)和平均通过时间(MTT)图。用于DSC-MRI的多回波(ME)方法的优点是：1)R2*可以在不受T1增强干扰的情况下测量；2)不需要预注药基线信号；3)动脉输入功能的自动选择可以基于第一个回波；4)如果所有回波的R2*的动态范围太小，则可以仅分析第一个回波。与并行成像(PI)相结合，可以获得较高的时空分辨率。PI还可以减少与EPI相关的图像伪影。ME和PI的这种结合称为渗透。方法和讨论：所有扫描均在1.5T Signa扫描仪(GE Medical Systems)上进行，具有8元组头部阵列。扫描参数为：15层(5 mm厚，间隔1 mm)，视野24 cm，分辨率96°96，TE=13.8，31.6，49.4ms(R=3)，TE=12.4，27.3，42.2，57.1 ms(R=4)，重复100次，TR=1225ms，带宽100 kHz，翻转角70。回波个数等于R，采用GRAPPA算法进行重建。单次注射Gd-DTPA 0.1mmo1/kgGd-DTPA4ml/S，然后用生理盐水冲洗20ml。使用从第一次回波中自动选择的AIF，通过块循环SVD计算示踪剂到达时间不敏感的去卷积(PSVD=10%)的灌注图。灰质和白质之间的CBF/CBV比率通过手动绘制的ROI中的值来估计。脑血流灌注图上可清楚地显示灰质和白质。AIF表明，第一个回波对于AIF选择具有最佳的动态范围，并被用于进一步的CBV/CBF分析。2名受试者的灰质/白质比率与先前报道的值一致。