Due to its capacity to recover oxy- and deoxyhemoglobin concentrations, functional near-IR imaging is a promising method for neuroimaging and brain mapping. However, because tissues naturally scatter much NIR light, strategies to improve image clarity and quantitative accuracy must be considered. The functional near-IR spectroscopy (fNIRS)-based optical imaging of the brain has recently undergone what a study team describes as significant advancements (diffuse optical tomography).
The advancement depends on improvements to the reconstructed image quality made possible by incorporating phase shift measurements, representing the NIR light’s time-of-flight, into the tomographic reconstruction. The project team claims that the phase measurements have generally been ignored in earlier studies that used frequency-domain near-IR spectroscopy to determine hemoglobin concentrations.
The study directly applies to diffuse optical tomography (DOT). This well-known method places NIR optical source and detector elements in a dense grid to produce overlapping measurements that can be converted into tomographic images through computational analysis.
Due to the required dynamic range, implementing a frequency-domain (FD) multidistance approach to high definition, DOT has previously proven difficult. But to ascertain whether the method could achieve improved resolution and imaging depth in brain regions, the new study compared imaging resolution and accuracy between continuous wave (CW) and FD high-resolution DOT. According to reports, this is the first study of frequency-domain and continuous-wave methods for DOT functional brain imaging.
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