Mind Research Network, Albuquerque, NM 87106, USA.
IEEE Trans Biomed Eng. 2011 Oct;58(10):2995-9. doi: 10.1109/TBME.2011.2158823. Epub 2011 Jun 7.
Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is a widely used method for brain mapping. BOLD fMRI signal detection is based on an intravoxel dephasing mechanism. This model involves bulk nuclear spin precession in a BOLD-induced inhomogeneous magnetic field within a millimeter-resolution voxel, that is, BOLD signal formation spans a huge spatial scale range from Angstrom to millimeter. In this letter, we present a computational model for multiresolution BOLD fMRI simulation, which consists of partitioning the nuclear spin pool into spin packets at a mesoscopic scale (∼10(-6) m), and calculating multiresolution voxel signals by grouping spin packets at a macroscopic scale range (10(-5) to 10(-3) m). Under a small-angle approximation, we find that the BOLD signal intensity is related to its phase counterpart (or BOLD fieldmap) across two spatial resolution levels.
血氧水平依赖 (BOLD) 功能磁共振成像 (fMRI) 是一种广泛用于脑映射的方法。BOLD fMRI 信号检测基于体素内去相位机制。该模型涉及到在 BOLD 诱导的非均匀磁场中体素内的大量核自旋进动，即 BOLD 信号形成跨越从埃到毫米的巨大空间尺度范围。在这封信中，我们提出了一种用于多分辨率 BOLD fMRI 模拟的计算模型，该模型包括将核自旋池在介观尺度 (∼10(-6) m) 上分成自旋包，并通过在宏观尺度范围内 (10(-5) 到 10(-3) m) 对自旋包进行分组来计算多分辨率体素信号。在小角度近似下，我们发现 BOLD 信号强度与其相位对应物 (或 BOLD 场图) 跨越两个空间分辨率水平相关。
