Comparison of multi-distance and multi-frequency methods in frequency-domain near-infrared spectroscopy

Frequency-domain near-infrared spectroscopy (FD-NIRS) can measure absolute tissue optical properties for functional brain imaging. Multiple source-detector separations (SDS), and multiple modulation frequencies can be used for FD-NIRS application in homogeneous or multi-layer tissue models. A multiple-frequency approach is advantageous in building more compact systems with a single SDS. In this work, we compare the accuracy of estimating absolute optical properties of a multi-layered tissue model using multi-distance and multi-frequency approaches. We demonstrate that the multiple-frequency approach is comparable in accuracy to the multiple-distance approach and can be confidently implemented for brain imaging applications.