Maldjian Joseph A, Laurienti Paul J, Driskill Lance, Burdette Jonathan H
Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
AJNR Am J Neuroradiol. 2002 Jun-Jul;23(6):1030-7.
The purpose of this study was to evaluate a variety of reproducibility indices for cognitive functional MR imaging (fMRI) paradigms that account for both overlapping and extraneous regions of activation.
Eight right-handed volunteers were imaged with fMRI by using a word-generation paradigm and a forward-backward text-listening paradigm. The paradigms were performed twice in the session and repeated 1 week later. Reproducibility indices for the four repeated studies were determined on the basis of pair-wise computation of the ratio of the probability-weighted intersection volume divided by the union volume of surviving activation clusters. The intersection volume was determined by using several iterations of the morphologic dilatation operator with additional voxels accrued in the intersection weighted by an exponential function. Computed indices included global reproducibility, language area reproducibility, extraneous activation reproducibility, and laterality.
The word-generation paradigm had reproducibility values that were significantly greater than those of the forward-backward text-listening paradigm (global reproducibility, 0.75 vs 0.5, P <.005; language area reproducibility, 0.85 vs 0.6, P <.008; mean extraneous activation reproducibility, 0.68 vs 0.41, P <.002). The forward-backward text-listening paradigm demonstrated more focal activations, whereas the word-generation demonstrated larger activations outside the dominant language areas that were highly reproducible.
For clinically relevant language paradigms, multiple reproducibility indices should be taken into account in selecting an appropriate paradigm. Compared with a forward-backward text-listening task, a word-generation task has higher reproducibility indices at the expense of localizing ability. The forward-backward paradigm demonstrates more focal activations with less extraneous activation.
本研究旨在评估认知功能磁共振成像（fMRI）范式的多种可重复性指标，这些指标兼顾了激活的重叠区域和无关区域。
8名右利手志愿者通过单词生成范式和前后向文本听力范式进行fMRI成像。这些范式在同一时段内进行两次，并在1周后重复。基于配对计算概率加权交集体积与存活激活簇并集体积的比值，确定四项重复研究的可重复性指标。通过使用形态学膨胀算子的多次迭代来确定交集体积，在交集中额外增加的体素由指数函数加权。计算得到的指标包括总体可重复性、语言区域可重复性、无关激活可重复性和偏侧性。
单词生成范式的可重复性值显著高于前后向文本听力范式（总体可重复性，0.75对0.5，P<.005；语言区域可重复性，0.85对0.6，P<.008；平均无关激活可重复性，0.68对0.41，P<.002）。前后向文本听力范式显示出更局灶性的激活，而单词生成范式在优势语言区域之外显示出更大且高度可重复的激活。
对于临床相关的语言范式，在选择合适的范式时应考虑多种可重复性指标。与前后向文本听力任务相比，单词生成任务具有更高的可重复性指标，但以定位能力为代价。前后向范式显示出更局灶性的激活且无关激活较少。
