Asemani Davud, Morsheddost Hassan, Shalchy Mahsa Alizadeh
Division of Radiology, Medical University of South Carolina, Charleston, SC 29407, USA.
Biomedical Engineering Department, K. N. Toosi University of Technology, Tehran, Iran.
Healthc Technol Lett. 2017 Jun 26;4(3):109-114. doi: 10.1049/htl.2017.0005. eCollection 2017 Jun.
Functional magnetic resonance imaging (fMRI) can generate brain images that show neuronal activity due to sensory, cognitive or motor tasks. Haemodynamic response function (HRF) may be considered as a biomarker to discriminate the Alzheimer disease (AD) from healthy ageing. As blood-oxygenation-level-dependent fMRI signal is much weak and noisy, particularly for the elderly subjects, a robust method is necessary for HRF estimation to efficiently differentiate the AD. After applying minimum description length wavelet as an extra denoising step, deconvolution algorithm is here employed for HRF estimation, substituting the averaging method used in the previous works. The HRF amplitude peaks are compared for three groups HRF of young, non-demented and demented elderly groups for both vision and motor regions. Prior works often reported significant differences in the HRF peak amplitude between the young and the elderly. The authors' experimentations show that the HRF peaks are not significantly different comparing the young adults with the elderly (either demented or non-demented). It is here demonstrated that the contradictory findings of the previous studies on the HRF peaks for the elderly compared with the young are originated from the noise contribution in fMRI data.
功能磁共振成像（fMRI）可以生成大脑图像，显示由于感觉、认知或运动任务而产生的神经元活动。血液动力学响应函数（HRF）可被视为区分阿尔茨海默病（AD）与健康衰老的生物标志物。由于基于血氧水平依赖的fMRI信号非常微弱且有噪声，特别是对于老年受试者，需要一种稳健的方法来估计HRF，以有效区分AD。在应用最小描述长度小波作为额外的去噪步骤后，本文采用反卷积算法进行HRF估计，取代了先前研究中使用的平均方法。比较了年轻组、非痴呆老年组和痴呆老年组在视觉和运动区域的三组HRF的HRF幅度峰值。先前的研究经常报道年轻人和老年人之间HRF峰值幅度存在显著差异。作者的实验表明，将年轻人与老年人（痴呆或非痴呆）进行比较时，HRF峰值没有显著差异。本文证明，先前关于老年人与年轻人HRF峰值的研究结果相互矛盾，是由于fMRI数据中的噪声所致。
