A team of researchers at Wright
State University has demonstrated for the first time that optical blood flow contrast
measured by Diffuse Correlation Spectroscopy (DCS) can be used to detect Resting
State Functional Connectivity (RSFC) in the human brain. RSFC indicates
spontaneous activity of the resting brain showing high synchronization in
functionally related regions, adjacent or even remote regions. These in sync regions
are known as “networks”. This phenomena was first uncovered by a functional
magnetic resonance imaging (fMRI) study using blood-oxygen-level dependent
(BOLD) signals that indicates oxygenation levels of the cerebral blood. Abnormalities
in RSFC have been associated with neuronal disorders such as autism,
Alzheimer’s, and depression. Thus, RSFC studies represent a valuable tool for
studying patients with disorders that can make performance of task-based
assessments difficult. However, many such patients,
such as young autistic children, are poor candidates for assessment by fMRI, which requires patients to hold still for long
intervals inside a confined imaging space with loud noise from the magnet.Optical imaging is fast, wearable, thus highly
suitable for the most patients.
The research was led by an optical imaging expert Dr. Ulas
Sunar, an associate professor of
Biomedical, Industrial and Human Factors Engineering and the Ohio Research Scholar
for Medical Imaging at Wright State University, along with Dr. Jun Li, Chien
Poon, Jeremy Kress and Dr. Dan Rohrbach. The team has recently published in
Journal of Biophotonics the first validated use of optical blood flow contrast to
detect RSFC in the human brain. DCS is a relatively new optical technology based
on detecting light scattering from moving blood cells and can quantify absolute
cerebral blood flow related contrast. It is a complementary technique to widely
known functional near infrared spectroscopy (fNIRS) that measures blood oxygenation.
The Sunar group used blood flow
parameter to quantify RSFC in in nine healthy adult males as a proof-of-concept
study. To determine whether DCS-based CBF could accurately detect RSFC, two
areas of the brain with known RSFC properties were examined. Connectivity between two sites within the
left and right dorsolateral frontal cortex (DLFC) were chosen, as they are
known to have strong connectivity. Also,
connectivity between the inferior frontal cortex (IFC) and the DLFC were
chosen, as they are known to have low connectivity. The DCS technique showed high connectivity withinthe DLFC areas, butlower connectivity between the IFC and DLFC areas, which
matches similar studies performed previously with other methods such as fMRI.
“These are exciting results in our field since the study has proven the
potential of DCS as a non-invasive means to assess RSFC in humans. Cerebral blood flow is a avery important parameter for neuronal disease characterization and it can show much higher contrast than other parameters such as cerebral oxygenation” said Sunar.
The optical imaging set-ups are far less sensitive to motion artifacts than fMRI and have been successfully used for functional brain imaging even in very young infants.The Sunar team is planning to utilize DCS technique for accurate characterization of neuronal diseases such as autism. They anticipate that this modality will ultimately become a highly useful tool for non-invasively assessing brain function in young and disabled patients.
Journal of Biophotonics
publication: https://onlinelibrary.wiley.com/doi/abs/10.1002/jbio.201700165
Sunar Research Group: http://biomil.org