Quantifying cardiac-induced brain tissue expansion using DENSE
Quantifying cardiac-induced brain tissue expansion using DENSE
复制标题
DOI：
10.1002/nbm.4050
复制
发表时间：
2019-02-01
影响因子：
2.9
通讯作者：
Zwanenburg, Jaco J. M.
中科院分区：
文献类型：
--
作者：
Adams, Ayodeji L.;Kuijf, Hugo J.;Zwanenburg, Jaco J. M.
脑组织经历粘弹性变形和体积应变，因为它在心动周期内由于底层微血管系统内的血容量变化而膨胀。因此，体积应变测量可以提供对小血管功能和组织粘弹性性质的了解。通过刺激回波的位移编码（DENSE）是一种MRI技术，可以量化与脑组织运动相关的亚毫米级位移。尽管以前的研究报告使用DENSE和其他MRI技术的脑组织位移，脑组织体积应变在心动周期的完整图片尚未获得。为了满足这一需求，我们在7 T和3 T下实施了3D电影-DENSE，以研究测量心脏诱导的体积应变作为小血管血容量变化标记的可行性。在6名健康受试者中，分别计算了整个脑以及灰质和白色组织在整个心动周期内的体积应变。使用信噪比（SNR）测量来确定逐体素的体积应变噪声。在7 T（平均值+/- SD）下的平均峰值全脑体积应变为（4.5 +/- 1.0）x 10（-4）（对应于0.48 +/- 0.1 mL的体积膨胀），这与脑脊液移位到椎管中以维持稳定颅内压的文献值一致。灰色与白色物质的峰值体积应变比为4.4 +/- 2.8，反映了这些组织类型之间的血容量和组织硬度差异。灰质和白色组织的平均峰值体积应变存在显著差异（p < 0.001）。在7 T和3 T下的DENSE测量的平均SNR分别为22.0 +/- 7.3和7.0 +/- 2.8，这目前限制了在两种场强下的体素应变分析。我们证明，组织特异性定量的体积应变是可行的与DENSE。该指标具有研究健康和疾病状态下衰老大脑中血容量脉动的潜力。
Brain tissue undergoes viscoelastic deformation and volumetric strain as it expands over the cardiac cycle due to blood volume changes within the underlying microvasculature. Volumetric strain measurements may therefore provide insights into small vessel function and tissue viscoelastic properties. Displacement encoding via stimulated echoes (DENSE) is an MRI technique that can quantify the submillimetre displacements associated with brain tissue motion. Despite previous studies reporting brain tissue displacements using DENSE and other MRI techniques, a complete picture of brain tissue volumetric strain over the cardiac cycle has not yet been obtained. To address this need we implemented 3D cine-DENSE at 7 T and 3 T to investigate the feasibility of measuring cardiac-induced volumetric strain as a marker for small vessel blood volume changes. Volumetric strain over the entire cardiac cycle was computed for the whole brain and for grey and white matter tissue separately in six healthy human subjects. Signal-to-noise ratio (SNR) measurements were used to determine the voxel-wise volumetric strain noise. Mean peak whole brain volumetric strain at 7 T (mean +/- SD) was (4.5 +/- 1.0) x 10(-4) (corresponding to a volume expansion of 0.48 +/- 0.1 mL), which is in agreement with literature values for cerebrospinal fluid that is displaced into the spinal canal to maintain a stable intracranial pressure. The peak volumetric strain ratio of grey to white matter was 4.4 +/- 2.8, reflecting blood volume and tissue stiffness differences between these tissue types. The mean peak volumetric strains of grey and white matter tissue were found to be significantly different (p < 0.001). The mean SNR at 7 T and 3 T of the DENSE measurements was 22.0 +/- 7.3 and 7.0 +/- 2.8 respectively, which currently limits a voxel-wise strain analysis at both field strengths. We demonstrate that tissue specific quantification of volumetric strain is feasible with DENSE. This metric holds potential for studying blood volume pulsations in the ageing brain in healthy and diseased states.