Measurements of dynamic near-infrared (NIR) light attenuation across the human head together with model-based image reconstruction algorithms allow the recovery of three-dimensional spatial brain activation maps. Previous studies using high-density diffuse optical tomography (HD-DOT) systems have reported improved image quality over sparse arrays. These HD-DOT systems incorporated multidistance overlapping continuous wave measurements that only recover differential intensity attenuation. We investigate the potential improvement in reconstructed image quality due to the additional incorporation of phase shift measurements, which reflect the time-of-flight of the measured NIR light, within the tomographic reconstruction from high-density measurements. To evaluate image reconstruction with and without the additional phase information, we simulated point spread functions across a whole-scalp field of view in 24 subject-specific anatomical models using an experimentally derived noise model. The addition of phase information improves the image quality by reducing localization error by up to 59% and effective resolution by up to 21% as compared to using the intensity attenuation measurements alone. Furthermore, we demonstrate that the phase data enable images to be resolved at deeper brain regions where intensity data fail, which is further supported by utilizing experimental data from a single subject measurement during a retinotopic experiment.

中文翻译：

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基于频域测量的高密度功能漫射光学层析成像技术可改善图像质量和空间分辨率。

测量基于人头的动态近红外（NIR）光衰减以及基于模型的图像重建算法，可以恢复三维空间大脑激活图。先前使用高密度扩散光学层析成像（HD-DOT）系统的研究已经报告了较稀疏阵列改善的图像质量。这些HD-DOT系统结合了多距离重叠连续波测量，只能恢复差分强度衰减。我们调查了由于高密度测量层析成像重建中相移测量的额外结合而产生的潜在图像质量改进，相移测量反映了被测NIR光的飞行时间。要评估有无附加相位信息的图像重建，我们使用实验得出的噪声模型在24个特定于对象的解剖模型中模拟了整个头皮视野上的点扩散函数。与仅使用强度衰减测量相比，相信息的添加通过将定位误差降低了59％，将有效分辨率降低了21％，从而改善了图像质量。此外，我们证明了相位数据使图像能够在强度数据失败的较深的大脑区域进行分辨，这通过在视黄醛实验中利用来自单个受试者测量的实验数据进一步得到支持。与仅使用强度衰减测量相比，相信息的添加通过将定位误差降低了59％，将有效分辨率降低了21％，从而改善了图像质量。此外，我们证明了相位数据使图像能够在强度数据失败的较深大脑区域进行分辨，这通过在视黄醛实验中利用来自单个受试者测量的实验数据进一步得到支持。与仅使用强度衰减测量相比，相信息的添加通过将定位误差降低了59％，将有效分辨率降低了21％，从而改善了图像质量。此外，我们证明了相位数据使图像能够在强度数据失败的较深的大脑区域进行分辨，这通过在视黄醛实验中利用来自单个受试者测量的实验数据进一步得到支持。