Yetkin F Z, Haughton V M, Cox R W, Hyde J, Birn R M, Wong E C, Prost R
Department of Radiology, Medical College of Wisconsin, Doyne Hospital, Milwaukee 53226, USA.
AJNR Am J Neuroradiol. 1996 Jun-Jul;17(6):1005-9.
To evaluate the effect of objects moving outside the field of view on functional MR imaging.
Echo-Planar image sequences were acquired in the sagittal plane of a stationary phantom or of the head of a volunteer subject while a second phantom was moved periodically outside the field of view. The signal intensity changes in each pixel within the field of view were measured.
Movement of the phantom outside the field of view produced signal intensity changes in the field of view that equaled or exceeded typical functional activation without the latency that characterizes activation. The greatest changes occurred at the bottom and top edges in the phantom and at the interfaces in the head.
If temporally correlated with the performance of a task, movement of objects or tissues outside the field of view may produce artifactual changes in signal intensity. The artifactual signal intensity changes were characterized by their location, greater magnitude, and more rapid rise to maximum than seen with typical "activation."
评估视野外物体移动对功能磁共振成像的影响。
在静止的模体或志愿者头部的矢状面采集回波平面图像序列，同时第二个模体在视野外做周期性移动。测量视野内每个像素的信号强度变化。
模体在视野外的移动在视野内产生了信号强度变化，其等于或超过了典型的功能激活，且没有激活所特有的延迟。最大的变化发生在模体的底部和顶部边缘以及头部的界面处。
如果与任务执行在时间上相关，视野外物体或组织的移动可能会在信号强度上产生伪影变化。伪影信号强度变化的特征在于其位置、更大的幅度以及比典型“激活”更快地上升到最大值。
