Is it possible to measure hemodynamic changes in the prefrontal cortex through the frontal sinus using continuous wave DOT systems?

Abstract

The present work shows the capability of near infrared (NIR) light to reach the cerebral cortex through the frontal sinus using continuous-wave techniques (CW-DOT) in a dual study. On the one hand, changes in time during the tracking of a blood dye in the prefrontal cortex were monitored. On the other hand, hemodynamic changes induced by low frequency of transcranial magnetic stimulation applied on the prefrontal cortex were recorded. The results show how NIR light projected through the frontal sinus reaches the cerebral cortex target, providing enough information to have a reliable measurement of cortical hemodynamic changes using CW-DOT.

Diffuse Optical Tomography Using Bayesian Filtering in the Human Brain

“…Peak The results show that DOT detects the same areas as fMRI at a functional level. These results can be used to corroborate the reliability of Bayesian filtering applied on the frontal cortex through a cognitive task crossing barrier, such as the presence of frontal sinus where scalp-brain distance vary across the subject [13]. Additionally, cognitive signals generate more subtle relative activation changes, unlike motor or visual tasks.…”

“…The optical properties for each tissue layer in the human head were measured according to the distance between the source-detector pairs that were placed on the head surface. At a distance of around 3-4 cm between a source-detector pair, the photons contain information regarding the optical properties from both intracerebral and extracerebral layers, whereas, at a distance of 1-2 cm between the source-detector pair, the photons contain mostly information from extracerebral layers [13].…”

“…The high fidelity of Bayesian filtering on raw DOT data has been tested using motor tasks to generate cerebral activity in temporal lobes [29], even during transcranial magnetic stimulation [13]. Some studies have used the Bayesian method in different steps during the DOT reconstruction, such as in the inverse problem [30], in order to improve the depth accuracy for the forward model [31], or to remove the scalp artefact [32], but most of them have tested the method in phantoms or simulation models Table 1.…”

Diffuse optical tomography in the human brain: A briefly review from the neurophysiology to its applications

“…Two studies have showed the reliability of Bayesian‐filtering on raw DOT data, one based on hemodynamic response measurement during a cognitive task [72], and another during repetitive transcranial magnetic stimulation [92]…”