Kinahan P E, Noll D C
Department of Radiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, Pennsylvania, 15213, USA.
Neuroimage. 1999 Apr;9(4):430-8. doi: 10.1006/nimg.1998.0420.
We present the results of a direct comparison of single-subject activation using identical tasks for both functional PET and fMRI whole-brain studies. We examined the most commonly employed methods for each modality. For fMRI this is the blood oxygenation level-dependent (BOLD) contrast method with echo-planar imaging. In PET single-subject activation studies are based on the development of high sensitivity 3D imaging of regional cerebral blood flow from multiple [15O]water injections. The identical activation paradigm of a visually cued sequential finger opposition was used for PET and fMRI. For both modalities the entire brain volume difference images were smoothed to the same final resolution and the peak t value within the primary sensory/motor (PSM) area was then identified. All contiguous voxels in the PSM above a predetermined threshold of statistical significance were determined. Finally, the difference-weighted centroid location was calculated for the PSM region for each modality. These studies showed a very similar pattern of activation, with the volume of activation greater in fMRI and higher levels of statistical significance. The centroids of activation, however, differed by 9 +/- 3 mm between the modalities, with the fMRI centroid location dorsal to that for PET. These results were stable across all processing options including differing levels of image smoothing and thresholds of statistical significance. These results are consistent with the hypothesis that draining veins contribute a substantial signal for fMRI activation studies and indicate caution for the interpretation of BOLD fMRI images with activation sites near draining veins.
我们展示了在功能性正电子发射断层扫描（PET）和功能磁共振成像（fMRI）全脑研究中使用相同任务进行单受试者激活的直接比较结果。我们研究了每种成像方式最常用的方法。对于fMRI，这是使用回波平面成像的血氧水平依赖（BOLD）对比法。在PET单受试者激活研究中，是基于多次注射[15O]水后对局部脑血流量进行高灵敏度三维成像技术的发展。PET和fMRI使用了相同的视觉提示顺序手指对指激活范式。对于这两种成像方式，将全脑体积差异图像平滑到相同的最终分辨率，然后确定初级感觉/运动（PSM）区域内的峰值t值。确定PSM中所有高于预定统计显著性阈值的相邻体素。最后，计算每种成像方式下PSM区域的差异加权质心位置。这些研究显示出非常相似的激活模式，fMRI中的激活体积更大，统计显著性水平更高。然而，两种成像方式的激活质心相差9±3毫米，fMRI的质心位置在PET的质心位置背侧。这些结果在所有处理选项中都是稳定的，包括不同程度的图像平滑和统计显著性阈值。这些结果与以下假设一致，即引流静脉对fMRI激活研究贡献了大量信号，并表明在解释引流静脉附近有激活位点的BOLD fMRI图像时需谨慎。
