Radiation Physics, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
Eur Radiol. 2012 May;22(5):998-1007. doi: 10.1007/s00330-011-2336-7. Epub 2011 Nov 24.
Brain segmentation and volume estimation of grey matter (GM), white matter (WM) and cerebro-spinal fluid (CSF) are important for many neurological applications. Volumetric changes are observed in multiple sclerosis (MS), Alzheimer's disease and dementia, and in normal aging. A novel method is presented to segment brain tissue based on quantitative magnetic resonance imaging (qMRI) of the longitudinal relaxation rate R(1), the transverse relaxation rate R(2) and the proton density, PD.
Previously reported qMRI values for WM, GM and CSF were used to define tissues and a Bloch simulation performed to investigate R(1), R(2) and PD for tissue mixtures in the presence of noise. Based on the simulations a lookup grid was constructed to relate tissue partial volume to the R(1)-R(2)-PD space. The method was validated in 10 healthy subjects. MRI data were acquired using six resolutions and three geometries.
Repeatability for different resolutions was 3.2% for WM, 3.2% for GM, 1.0% for CSF and 2.2% for total brain volume. Repeatability for different geometries was 8.5% for WM, 9.4% for GM, 2.4% for CSF and 2.4% for total brain volume.
We propose a new robust qMRI-based approach which we demonstrate in a patient with MS.
• A method for segmenting the brain and estimating tissue volume is presented • This method measures white matter, grey matter, cerebrospinal fluid and remaining tissue • The method calculates tissue fractions in voxel, thus accounting for partial volume • Repeatability was 2.2% for total brain volume with imaging resolution <2.0 mm.
对灰质（GM）、白质（WM）和脑脊液（CSF）进行脑部分割和容量估计对于许多神经学应用非常重要。在多发性硬化症（MS）、阿尔茨海默病和痴呆症以及正常衰老中，都观察到了容积变化。本文提出了一种新的方法，基于纵向弛豫率 R(1)、横向弛豫率 R(2)和质子密度 PD 的定量磁共振成像（qMRI）对脑组织进行分割。
使用之前报道的 WM、GM 和 CSF 的 qMRI 值来定义组织，并进行布洛赫模拟，以研究存在噪声时组织混合物的 R(1)、R(2)和 PD。基于模拟结果构建了一个查找网格，以将组织部分体积与 R(1)-R(2)-PD 空间相关联。该方法在 10 名健康受试者中进行了验证。使用六种分辨率和三种几何形状采集 MRI 数据。
不同分辨率的重复性为 WM 为 3.2%、GM 为 3.2%、CSF 为 1.0%、总脑体积为 2.2%。不同几何形状的重复性为 WM 为 8.5%、GM 为 9.4%、CSF 为 2.4%、总脑体积为 2.4%。
我们提出了一种新的稳健的基于 qMRI 的方法，并在一名 MS 患者中进行了验证。
· 提出了一种分割大脑和估计组织体积的方法· 该方法测量白质、灰质、脑脊液和剩余组织· 该方法在体素中计算组织分数，从而考虑了部分体积· 当成像分辨率<2.0mm 时，总脑体积的重复性为 2.2%。
