Significance: Functional near-infrared spectroscopy (fNIRS) is an emerging brain imaging technique due to its small size, low cost, minimum scanning sonic noise, and portability. Unfortunately, because this technique does not provide neuroanatomical information to accompany the functional data, its data interpretation remains a persistent challenge in fNIRS brain imaging applications. The two most popular approaches for fNIRS anatomical registration are magnetic resonance imaging (MRI) and three-dimensional (3-D) digitization. MRI scanning yields high-precision registration but reduces the cost-effectiveness and accessibility of fNIRS imaging. Alternatively, the low cost and portable 3-D digitizers are affected by magnetic properties of ambient metal objects, including participant clothing, testing equipment, medical implants, and so forth. Aim: To overcome these obstacles and provide accessible and reliable neuroanatomical registration for fNIRS imaging, we developed and explored a photogrammetry optode registration (POR) method. Approach: The POR method uses a consumer-grade camera to reconstruct a 3-D image of the fNIRS optode-set, including light emitters and detectors, on a participant’s head. This reconstruction process uses a linear-time incremental structure from motion (LTI-SfM) algorithm, based on 100 to 150 digital photos. The POR method then aligns the reconstructed image with an anatomical template of the brain. Results: To validate this method, we tested 22 adult and 19 child participants using the POR method and MRI imaging. The results comparisons suggest on average 55% and 46% overlap across all data channel measurements registered by the two methods in adult and children, respectively. Importantly, this overlap reached 65% and 60% in only the frontal channels. Conclusions: These results suggested that the mismatch in registration was partially due to higher variation in backward optode placement rather than the registration efficacy. Therefore, the photo-based registration method can offer an accessible and reliable approach to neuroanatomical registration of fNIRS as well as other surface-based neuroimaging and neuromodulation methods.

中文翻译：

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基于摄影测量的功能性近红外光谱立体光极配准方法。

意义：功能性近红外光谱 (fNIRS) 是一种新兴的大脑成像技术，因为它体积小、成本低、扫描声波噪声最小，而且便于携带。不幸的是，由于该技术不提供伴随功能数据的神经解剖学信息，其数据解释在 fNIRS 脑成像应用中仍然是一个持续的挑战。fNIRS 解剖配准的两种最流行的方法是磁共振成像 (MRI) 和三维 (3-D) 数字化。MRI 扫描产生高精度配准，但降低了 fNIRS 成像的成本效益和可及性。或者，低成本和便携式 3-D 数字化仪受到周围金属物体磁性的影响，包括参与者服装、测试设备、医疗植入物等。目的：为了克服这些障碍并为 fNIRS 成像提供可访问且可靠的神经解剖学配准，我们开发并探索了一种摄影测量光极配准 (POR) 方法。方法：POR 方法使用消费级相机重建参与者头部的 fNIRS 光极集的 3D 图像，包括光发射器和检测器。此重建过程使用基于运动的线性时间增量结构 (LTI-SfM) 算法，基于 100 到 150 张数码照片。POR 方法然后将重建的图像与大脑的解剖模板对齐。结果：为了验证该方法，我们使用 POR 方法和 MRI 成像测试了 22 名成人和 19 名儿童参与者。结果比较表明，这两种方法分别在成人和儿童中记录的所有数据通道测量值平均有 55% 和 46% 的重叠。重要的是，这种重叠仅在正面通道中达到了 65% 和 60%。结论：这些结果表明配准的不匹配部分是由于向后光极放置的变化较大，而不是配准效率。因此，基于照片的配准方法可以为 fNIRS 的神经解剖学配准以及其他基于表面的神经成像和神经调节方法提供一种可访问且可靠的方法。这些结果表明，配准的不匹配部分是由于向后光极放置的变化较大，而不是配准效率。因此，基于照片的配准方法可以为 fNIRS 的神经解剖学配准以及其他基于表面的神经成像和神经调节方法提供一种可访问且可靠的方法。这些结果表明，配准的不匹配部分是由于向后光极放置的变化较大，而不是配准效率。因此，基于照片的配准方法可以为 fNIRS 的神经解剖学配准以及其他基于表面的神经成像和神经调节方法提供一种可访问且可靠的方法。