The innovative methodology, reported in the SPIE journal Neurophotonics, shows that using frequency domain measurement in functional neuroimaging improves quality as well as depth resolution
a) High Density Diffuse Optical Tomography system with 158 sources (red) and 166 detectors (cyan), the surface of the brain is shown in pink and blue. b) Histogram of brain surface depth across 24 subjects with c) Brain surface depth probability distribution for each subject. The red stars mark the maximum probability for each subject while the red line is the most probable depth across all subjects (12.5 mm), highlighting the need of improving both image quality and spatial resolution.
BELLINGHAM, Washington, USA and CARDIFF, UK - In an article published today in the peer-reviewed, open-access SPIE publication Neurophotonics, "High density functional diffuse optical tomography based on frequency domain measurements improves image quality and spatial resolution," researchers demonstrate critical improvements to functional Near Infrared Spectroscopy (fNIRS)-based optical imaging in the brain.
fNIRS-based optical imaging is non-invasive and relatively inexpensive technology used where neuroimaging is required, applied in areas such as functional brain mapping, psychology studies, intensive care unit patient monitoring, mental disease monitoring, and early dementia diagnosis. Applying amplitude modulated light known as frequency domain (FD) — rather than the usual continuous wave NIR light — to obtain overlapping measurements of tissue via high-density diffuse optical tomography, the researchers were able to achieve higher resolution in their imaging while also enabling sensitivity to deeper brain regions. FD-NIRS has already been used in such areas as breast-lesion optical tomography, brain-trauma assessment and joint imaging. This is the first example of researchers comparing the FD-NIR application against CW in functional brain imaging.
According to Neurophotonics Associate Editor Rickson Mesquita, of the University of Campesinas' Institute of Physics in Sao Paolo, Brazil, the findings mark exciting new possibilities in the fNIRS arena: "I believe this manuscript can be significant from the methods perspective since it addresses important validation about DOT with frequency-domain (FD) data. Importantly, their simulations and data appear to show that, by adding the phase information from the FD data, the depth sensitivity is greatly improved. The results are carefully addressed, and the authors' conclusions are of great interest to the fNIRS community."
The article authors are Matthaios Doulgerakis and Hamid Dehghani of the University of Birmingham's School of Computer Science in Birmingham, UK, and Adam T. Eggebrecht of the Mallinckrodt Institute of Radiology at the Washington University School of Medicine in St. Louis, Missouri, USA.
Neurophotonics, an open-access journal, is published in print and digitally by SPIE in the SPIE Digital Library. Its editor-in-chief is Boston University Neurophotonics Center Director David Boas. The SPIE Digital Library contains more than 500,000 publications from SPIE journals, proceedings, and books, with approximately 18,000 new research papers added each year.
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