Crosson B, Williamson D J, Shukla S S, Honeyman J C, Nadeau S E
Department of Clinical and Health Psychology, College of Health Related Professions, University of Florida, Gainesville.
J Nucl Med. 1994 May;35(5):755-63.
This study extends and validates a system for localizing brain activity changes based on fiducial markers, coregistration of SPECT and MRI structural images and atlas/MRI-assisted localization.
Ten normal subjects underwent 99mTc-HMPAO SPECT during a resting eyes-closed baseline measurement and during visual stimulation (8-Hz reversing checkerboard). SPECT scans were registered with MRI scans obtained from each individual using a fiducial-based system that minimized z-axis and rotational errors, and registration was further refined along the x- and y-axes by superimposing corresponding axial SPECT and MRI slices. Regions of interest (ROIs) were located on MRI slices with the aid of an atlas. Corresponding loci on SPECT slices were chosen and incrementally adjusted such that the center of a ROI was located precisely at the maximum of activity in the visual cortex or the cortical gray matter ribbon.
Activity in the calcarine cortex increased by 44.39% during visual stimulation (p < 0.001). Adjustment of ROI location in accordance with local activity maxima yielded superior results to a method relying strictly on atlas/MRI localization. Premotor cortex activity declined by 16.91% on the right (p < 0.01) and 13.85% on the left (p > 0.05), whereas no changes occurred in the somatosensory cortex.
Changes in visual cortical activity were most comparable to previous functional MRI studies but also congruent with PET and SPECT findings. Using the locus of peak activity to aid in defining cortical ROIs improves the signal-to-noise ratio by reducing noise related to inevitable minor registration errors.
本研究扩展并验证了一种基于基准标记、单光子发射计算机断层扫描（SPECT）与磁共振成像（MRI）结构图像的配准以及图谱/MRI辅助定位来定位脑活动变化的系统。
10名正常受试者在静息闭眼基线测量期间以及视觉刺激（8赫兹反转棋盘格）期间接受了99m锝-六甲基丙二胺肟（99mTc-HMPAO）SPECT检查。使用基于基准的系统将SPECT扫描与从每个个体获得的MRI扫描进行配准，该系统可将z轴和旋转误差降至最低，并通过叠加相应的轴向SPECT和MRI切片在x轴和y轴上进一步优化配准。借助图谱在MRI切片上定位感兴趣区域（ROI）。选择SPECT切片上的相应位点并进行逐步调整，以使ROI的中心精确位于视觉皮层或皮质灰质带的活动最大值处。
视觉刺激期间，距状皮层的活动增加了44.39%（p < 0.001）。根据局部活动最大值调整ROI位置比严格依赖图谱/MRI定位的方法产生了更好的结果。右侧运动前皮层活动下降了16.91%（p < 0.01），左侧下降了13.85%（p > 0.05），而躯体感觉皮层未发生变化。
视觉皮层活动的变化与先前的功能MRI研究最为可比，但也与正电子发射断层扫描（PET）和SPECT的结果一致。利用活动峰值位点辅助定义皮层ROI可通过减少与不可避免的微小配准误差相关的噪声来提高信噪比。
