ABSTRACT

The reliable preoperative estimation of brain hemispheric asymmetry may be achieved through multiple lateralization indices using functional magnetic resonance imaging. Adding to our previously developed AveLI, we devised a novel threshold-free lateralization index, HomotopicLI, which computes a basic formula, (Left – Right) / (Left + Right), using voxel values of pairs located symmetrically in relation to the midsagittal line as the terms Left and Right, and averages them within the regions-of-interest. The study aimed to evaluate HomotopicLI before clinical applications. Data were collected from 56 healthy participants who performed four language tasks. We compared seven index types, including HomotopicLI, AveLI, and BaseLI; BaseLI was calculated using the sums of voxel values as the terms. Contrary to our expectations, HomotopicLI performed similarly to AveLI but better than BaseLI in detecting right dominance. A detailed analysis of unilaterally activated voxels of the homotopic pairs revealed that unilateral activation occurred more frequently on the right than on the left when HomotopicLI indicated right dominance. The voxel values during right unilateral activation were smaller than those in the left, causing right dominances in the homotopic pairs by HomotopicLI. These unique features provide an advantage in detecting residual, compensative functions spreading weakly in the non-dominant hemisphere.

摘要

大脑半球不对称性的可靠术前估计可以通过使用功能磁共振成像的多个偏侧化指数来实现。添加到我们之前开发的 AveLI 中，我们设计了一种新的无阈值偏侧化指数 HomotopicLI，它使用相对于中矢状线对称定位的对的体素值计算基本公式（左 - 右）/（左 + 右）作为术语左和右，并在感兴趣的区域内对它们进行平均。该研究旨在在临床应用前评估 HomotopicLI。数据收集自 56 名执行四项语言任务的健康参与者。我们比较了七种指标类型，包括 HomotopicLI、AveLI 和 BaseLI；BaseLI 是使用体素值的总和作为项计算的。与我们的预期相反，HomotopicLI 的表现与 AveLI 相似，但在检测右优势方面优于 BaseLI。对同伦对的单侧激活体素的详细分析表明，当 HomotopicLI 指示右优势时，单侧激活在右侧比在左侧更频繁地发生。右侧单侧激活期间的体素值小于左侧的体素值，导致 HomotopicLI 的同伦对中的右侧优势。这些独特的特征为检测在非优势半球微弱传播的残余补偿功能提供了优势。对同伦对的单侧激活体素的详细分析表明，当 HomotopicLI 指示右优势时，单侧激活在右侧比在左侧更频繁地发生。右侧单侧激活期间的体素值小于左侧的体素值，导致 HomotopicLI 的同伦对中的右侧优势。这些独特的特征为检测在非优势半球微弱传播的残余补偿功能提供了优势。对同伦对的单侧激活体素的详细分析表明，当 HomotopicLI 指示右优势时，单侧激活在右侧比在左侧更频繁地发生。右侧单侧激活期间的体素值小于左侧的体素值，导致 HomotopicLI 的同伦对中的右侧优势。这些独特的特征为检测在非优势半球微弱传播的残余补偿功能提供了优势。