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PROJECT 4: Functional Diffuse Optical Tomography of the Brain


David Boas , PhD Project Leader
Maria Angela Franceschini, PhD Investigator
Juliette Selb, PhD Investigator
Harsha Radhakrishnan, MS Research Associate


Project Description

Near Infrared Spectroscopy (NIRS) is a non-invasive, non-ionizing, and inexpensive monitoring and imaging technique that uses near-infrared light to probe tissue optical properties. Regional variations in oxy- and deoxy-hemoglobin concentration as well as cellular scattering can be imaged by monitoring spatial-temporal variations in the light absorption and scattering properties of tissue, giving NIRS the special ability to directly measure the hemodynamic, metabolic, and neuronal responses to brain activation. These capabilities make NIRS a useful stand-alone neuroimaging tool and useful complement to fMRI and EEG/MEG in studies of normal physiology and pathology, as evidenced by our publications and dissemination in the past grant cycles of this program.

During our previous grant cycle we completed hardware development of a real-time continuous-wave (CW) imaging instrument for measuring brain activation with improved spatial resolution afforded by overlapping measurements and signal processing to reduce the interference from systemic physiological fluctuations. Further, we developed a prototype time-domain (TD) imaging system that affords better depth sensitivity than CW and the ability to quantify baseline physiological properties of the brain. Current needs of the NIRS community include: 1) tools to facilitate interpretation of the brain activation images in the context of brain anatomy in adults and infants; and 2) access to portable TD imaging instrumentation that enables multispectral
measurements with an image acquisition rate of >2 Hz (necessary to overcome physiological interference).

Further, the good temporal resolution of NIRS has enabled us to comprehend well and design algorithms to filter the signal interference that arises from heart rate, respiration, and slower blood pressure fluctuations. This interference is common to fMRI and thus we propose to transfer know-how from our NIRS effort to fMRI to better filter this systemic physiological interference, enabling exploration of these systemic factors (including cerebral autoregulation) and improving the contrast-to-background ratio in fMRI studies of brain activation.



Imaging Facilities

Description of the Center's imaging equipment and support labs

Apply to conduct research with the Center as a collaborator or service user

Description of the optical imaging facilities used for Project 4



APU (Atlas-guided Photon-migration Utilities) provides utilities for using a structural MRI (from an atlas or any other MRI) to guide the analysis of Near Infra-Red Spectroscopy (NIRS) data. These tools are used in conjunction with Freesurfer and MNE. Detailed information about APU can be found here.

HOMER (Hemodynamic Evoked Response) graphical interface for visualization and analysis of Near Infra-Red Spectroscopy (NIRS) data

tMCing and Monte Carlo eXtreme (MCX) packages are used to model photon migration through 3D turbid media



A two-day intensive hands on introduction to Near Infrared Spectroscopy and Diffuse Optical Tomography


Electronic Tutorials

Learn more about how Diffuse Optical Tomography (DOT) is used for functional brain imaging