Silva A C, Zhang W, Williams D S, Koretsky A P
Pittsburgh NMR Center for Biomedical Research, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Magn Reson Med. 1995 Feb;33(2):209-14. doi: 10.1002/mrm.1910330210.
When a single coil is used to measure perfusion by arterial spin labeling, saturation of macromolecular protons occurs during the labeling period. Induced magnetization transfer contrast (MTC) effects decrease tissue water signal intensity, reducing the sensitivity of the technique. In addition, MTC effects must be properly accounted for in acquiring a control image. This forces the image to a single slice centered between the labeling plane and the control plane. In this work, a two-coil system is presented as a way to avoid saturation of macromolecular spins during arterial spin labeling. The system consists of one small surface coil for labeling the arterial water spins, and a head coil for MRI, actively decoupled from the labeling coil by using PIN diodes. It is shown that no signal loss occurs due to MTC effects when the two-coil system is used for MRI of rat brain perfusion, enabling three-dimensional perfusion imaging. Using the two-coil system, a multi-slice MRI sequence was used to study the regional effects of amphetamine on brain perfusion. Amphetamine causes significant increases in perfusion in many areas of the brain including the cortex, cingulate, and caudate putamen, in agreement with previous results using deoxyglucose uptake to monitor brain activation.
当使用单个线圈通过动脉自旋标记测量灌注时，在标记期会发生大分子质子的饱和。诱导的磁化传递对比（MTC）效应会降低组织水信号强度，从而降低该技术的灵敏度。此外，在获取对照图像时必须正确考虑MTC效应。这使得图像只能是位于标记平面和对照平面之间中心位置的单个切片。在这项工作中，提出了一种双线圈系统，作为在动脉自旋标记期间避免大分子自旋饱和的一种方法。该系统由一个用于标记动脉水自旋的小表面线圈和一个用于磁共振成像（MRI）的头部线圈组成，通过使用PIN二极管与标记线圈有效去耦。结果表明，当使用双线圈系统进行大鼠脑灌注的MRI时，不会因MTC效应而发生信号损失，从而能够进行三维灌注成像。使用双线圈系统，采用多层MRI序列研究了苯丙胺对脑灌注的区域影响。苯丙胺导致包括皮质、扣带回和尾状壳核在内的许多脑区灌注显著增加，这与先前使用脱氧葡萄糖摄取监测脑激活的结果一致。
