Quantitative evaluation of frequency domain measurements in high density diffuse optical tomography

Area of Science:

• Neuroimaging
• Biomedical Optics
• Optical Tomography

Background:

• Functional near-infrared spectroscopy (fNIRS) often relies on continuous wave (CW) data for high-density diffuse optical tomography (HD-DOT).
• Frequency domain (FD) HD-DOT with a single modulation frequency has shown improved localization of focal brain activation compared to CW data.

Purpose of the Study:

• To evaluate the performance enhancement of fNIRS HD-DOT by combining CW and FD measurements.
• To investigate the benefits of using multiple modulation frequencies in fNIRS HD-DOT.

Main Methods:

• Simulated CW and FD measurements at 78, 141, and 203 MHz in a layered cortical model.
• Evaluation of localization error, full width half maximum, and effective resolution with and without noise.

Main Results:

• FD measurements at 141 MHz outperformed CW by 8.4%; combining CW and FD improved performance by 21.7% over CW.
• Higher modulation frequencies (203 MHz) showed incremental benefits over lower ones (78 MHz).
• Combining CW and FD data across multiple modulation frequencies yielded the best imaging performance, outperforming single-frequency FD at 141 MHz by up to 3.92%.

Conclusions:

• Combining CW and FD measurements in HD-DOT enhances fNIRS imaging performance beyond FD alone.
• Higher modulation frequencies contribute to increased accuracy in fNIRS imaging.
• The optimal approach for superior fNIRS HD-DOT performance involves integrating CW and FD data across multiple modulation frequencies.