Significance: High density diffuse optical tomography (HD-DOT) as applied in functional near-infrared spectroscopy (fNIRS) is largely limited to continuous wave (CW) data. Using a single modulation frequency, frequency domain (FD) HD-DOT has recently demonstrated better localization of focal activation as compared to CW data. We show that combining CW and FD measurements and multiple modulation frequencies increases imaging performance in fNIRS. Aim: We evaluate the benefits of multiple modulation frequencies, combining different frequencies as well as CW data in fNIRS HD-DOT. Approach: A layered model was used, with activation occurring within a cortex layer. CW and FD measurements were simulated at 78, 141, and 203 MHz with and without noise. The localization error, full width half maximum, and effective resolution were evaluated. Results: Across the average of the three metrics, at 141 MHz, FD performed 8.4% better than CW, and the combination of CW and FD was 21.7% better than CW. FD measurements at 203 MHz performed 5% better than 78 MHz. Moreover, the three combined modulation frequencies of FD and CW performed up to 3.92% better than 141 MHz alone. Conclusions: We show that combining CW and FD measurements offers better performance than FD alone, with higher modulation frequencies increasing accuracy. Combining CW and FD measurements at multiple modulation frequencies yields the best overall performance.

中文翻译：

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高密度漫射光学断层扫描频域测量的定量评估


意义：应用于功能近红外光谱 (fNIRS) 的高密度漫反射光学断层扫描 (HD-DOT) 在很大程度上仅限于连续波 (CW) 数据。使用单一调制频率、频域 (FD) HD-DOT 最近证明，与 CW 数据相比，焦点激活的定位效果更好。我们证明，结合 CW 和 FD 测量以及多个调制频率可以提高 fNIRS 的成像性能。目标：我们评估多种调制频率的优势，结合不同频率以及 fNIRS HD-DOT 中的 CW 数据。方法：使用分层模型，激活发生在皮质层内。在有噪声和无噪声的情况下，在 78、141 和 203 MHz 下模拟 CW 和 FD 测量。评估了定位误差、半高全宽和有效分辨率。结果：从三个指标的平均值来看，在 141 MHz 下，FD 的性能比 CW 好 8.4%，而 CW 和 FD 的组合比 CW 好 21.7%。 203 MHz 下的 FD 测量性能比 78 MHz 好 5%。此外，FD 和 CW 的三个组合调制频率比单独的 141 MHz 性能提高了 3.92%。结论：我们表明，结合 CW 和 FD 测量可提供比单独使用 FD 更好的性能，并且更高的调制频率可提高精度。在多个调制频率下结合 CW 和 FD 测量可产生最佳的整体性能。