Department of Neurological and Movement Sciences, Section of Neurology, University of Verona, Italy.
Clin Neurophysiol. 2013 Nov;124(11):2108-18. doi: 10.1016/j.clinph.2013.05.024. Epub 2013 Jul 9.
Electroencephalography and functional magnetic resonance imaging (fMRI) can be combined to noninvasively map abnormal brain activation elicited by epileptic processes. A major aim was to investigate the impact of a subject-specific hemodynamic response function (HRF) to describe the differences across patients versus the use of a standard model.
We developed and applied on simulated and real data a method designed to choose optimum HRF model for identifying fMRI activation maps. In simulation, the ability of five models to reproduce data was assessed: four standard and an individual-based HRF model (ibHRF). In clinical data, drug-resistant epileptic patients underwent fMRI to investigate hemodynamic responses evoked by interictal activity.
When data are simulated with models different from the standard ones, the results obtained with ibHRF are superior to those obtained with the standard HRFs. Results on real data indicate an increase in extent and degree of activation with the ibHRF in comparison of the results obtainable using standard HRFs.
The use of the same HRF in all patients is inappropriate and resolves in biased extension of the activation maps.
The new method could represent an useful diagnostic tool for other clinical studies that may be biased because of misspecification of HRF.
脑电图和功能磁共振成像（fMRI）可结合使用，对癫痫过程引起的异常脑激活进行非侵入性定位。主要目的是研究使用特定于个体的血流动力学反应函数（HRF）描述患者间差异与使用标准模型的差异。
我们开发并应用了一种方法，旨在为识别 fMRI 激活图选择最佳 HRF 模型，该方法针对模拟和真实数据进行了设计。在模拟中，评估了五种模型再现数据的能力：四种标准模型和一种基于个体的 HRF 模型（ibHRF）。在临床数据中，耐药性癫痫患者接受 fMRI 检查以研究间歇期活动引起的血流动力学反应。
当用与标准模型不同的模型模拟数据时，ibHRF 获得的结果优于标准 HRF 获得的结果。真实数据的结果表明，与使用标准 HRF 获得的结果相比，ibHRF 可增加激活的范围和程度。
在所有患者中使用相同的 HRF 是不合适的，会导致激活图的有偏扩展。
该新方法可能成为其他临床研究的有用诊断工具，这些研究可能由于 HRF 的指定不当而存在偏差。
