Improving optical contact for functional near‑infrared brain spectroscopy and imaging with brush optodes.
Improving optical contact for functional near‑infrared brain spectroscopy and imaging with brush optodes.
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DOI：
10.1364/boe.3.000878
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发表时间：
2012-05-01
影响因子：
3.4
通讯作者：
Alexandrakis G
中科院分区：
文献类型：
--
作者：
Khan B;Wildey C;Francis R;Tian F;Delgado MR;Liu H;Macfarlane D;Alexandrakis G
设计并证明了一种新颖的刷光极，可以克服功能性近红外光谱 (fNIRS) 和成像过程中由于头发阻挡光而可能出现的与头皮光学接触不良的问题。刷光极作为现有商业平面（传统）光纤束光极的附件实现。目标是刷子光极将穿过头发并改善头发浓密的受试者的光学接触。进行了模拟和实验来评估这些改进的程度。对 17 名具有不同发色（金色、棕色和黑色）和头发密度（0-2.96 根头发/mm2）的受试者进行 FNIRS 测量，在手指敲击协议期间对扁平光极和刷状光极进行测量。使用刷光极扩展时，除了达到几乎 100% 的研究成功率之外，测量设置时间还减少了三倍。此外，刷光极使激活信噪比 (SNR) 提高了十倍，并且检测到的激活面积 (dAoA) 显着增加 (p < 0.05)。测得的信噪比改善与光子通过头皮和头发传播的蒙特卡罗 (MC) 模拟相匹配。此外，还导出了一个分析模型，以数学方式估计由于不同头发颜色和头发密度而观察到的光功率损失。有趣的是，尽管有一些简化的假设，推导的分析公式对实验数据和 MC 模拟结果产生了极好的估计。该分析模型使研究人员能够轻松估计给定受试者的平面光纤束和单根光纤因头发阻碍而造成的光功率损失。
A novel brush optode was designed and demonstrated to overcome poor optical contact with the scalp that can occur during functional near infrared spectroscopy (fNIRS) and imaging due to light obstruction by hair. The brush optodes were implemented as an attachment to existing commercial flat-faced (conventional) fiber bundle optodes. The goal was that the brush optodes would thread through hair and improve optical contact on subjects with dense hair. Simulations and experiments were performed to assess the magnitude of these improvements. FNIRS measurements on 17 subjects with varying hair colors (blonde, brown, and black) and hair densities (0–2.96 hairs/mm2) were performed during a finger tapping protocol for both flat and brush optodes. In addition to reaching a study success rate of almost 100% when using the brush optode extensions, the measurement setup times were reduced by a factor of three. Furthermore, the brush optodes enabled improvements in the activation signal-to-noise ratio (SNR) by up to a factor of ten as well as significant (p < 0.05) increases in the detected area of activation (dAoA). The measured improvements in SNR were matched by Monte Carlo (MC) simulations of photon propagation through scalp and hair. In addition, an analytical model was derived to mathematically estimate the observed light power losses due to different hair colors and hair densities. Interestingly, the derived analytical formula produced excellent estimates of the experimental data and MC simulation results despite several simplifying assumptions. The analytical model enables researchers to readily estimate the light power losses due to obstruction by hair for both flat-faced fiber bundles and individual fibers for a given subject.