Detailed Functional Neuroimaging in Open Environments with Wearable Diffuse Optical Tomography
Poster No:
1983
Submission Type:
Abstract Submission
Authors:
Hannah DeVore1, Alvin Agato1, Calamity Svoboda1, William Hamic1, Dana Wilhelm1, Sean Rafferty1, Jason Trobaugh1, Adam Eggebrecht2, Edward Richter1, Joseph Culver1
Institutions:
1Washington University in St. Louis, St. Louis, MO, 2Washington University School of Medicine, Eureka, MO
First Author:
Co-Author(s):
Introduction:
Over time, neuroimaging technologies have advanced towards the goal of a flexible, noninvasive, high-resolution, portable modality, but most established technologies face tradeoffs of portability, resolution, SNR, cost, and motion susceptibility. Established technologies like MRI have good spatial resolution and multiple contrast modes, but, in addition to contraindications, create a loud, cramped, unnatural scanning environment that cannot be translated to real-world settings. We present a wearable, high-density (WHD) diffuse optical tomography (DOT) system that brings high-quality neuroimaging into more ecologically valid contexts, including quiet, open, environments and even non-laboratory settings.
DOT is an optical technique that uses multiple, overlapping measurements from high-density imaging arrays to generate 3D tomographic reconstruction of cortical blood oxygenation dynamics. As with MRI, neuronal activity is inferred from blood oxygenation via neurovascular coupling. While fiber-based DOT systems have been extensively validated against MRI over the last decade (Eggebrecht, 2014), using a variety of tasks as well as resting state functional connectivity, full head fiber DOT systems still restrict subjects to controlled laboratory environments. New, wearable DOT systems have recently begun to provide similar imaging performance with the added advantage of portability and flexibility of use.
DOT is an optical technique that uses multiple, overlapping measurements from high-density imaging arrays to generate 3D tomographic reconstruction of cortical blood oxygenation dynamics. As with MRI, neuronal activity is inferred from blood oxygenation via neurovascular coupling. While fiber-based DOT systems have been extensively validated against MRI over the last decade (Eggebrecht, 2014), using a variety of tasks as well as resting state functional connectivity, full head fiber DOT systems still restrict subjects to controlled laboratory environments. New, wearable DOT systems have recently begun to provide similar imaging performance with the added advantage of portability and flexibility of use.
Methods:
WHD DOT adds portability to the benefits of standard fiber DOT. All the optoelectronics and mechanics have been integrated into a small-form-factor, lightweight, untethered cap powered by a battery in a backpack. The 98 sources and 98 detectors are arranged in a high-density grid with a field of view covering most of the cortex. Spring-loaded optodes comb through hair to create and maintain optode-scalp coupling. The system's portable, wireless design makes it easy to set up and operate the WHD system in different places and buildings, and its untethered nature allows participants to move their head, stand, walk, interact with others and their environment, and perform more complex movements (fig. 1).
Results:
Tested in vivo with a variety of task and resting state conditions, WHD's imaging performance is comparable to conventional fiber DOT, while boasting an improved form factor, portability, motion tolerance, and flexibility. Unlike other portable technologies like EEG and sparse NIRS, the WHD system has sufficient spatial resolution and SNR for complex mapping, encoding, or decoding studies. Its demonstrated capabilities include multi-class decoding with up to 100% accuracy, repeatable single-subject retinotopic mapping of visual angle and eccentricity (fig. 1), resting-state functional connectivity (fig. 2), and more, all while in a quiet, open, spacious environment with minimal-to-no restrictions on participant movement.
Conclusions:
DOT brought optical techniques into the world of high-resolution, large field-of-view neuroimaging, alongside MRI and PET, and WHD DOT is bringing that image quality into more ecologically valid settings. The wearable convenience brings new possibilities for scanning during tasks or in settings that were previously intractable; the accessibility of real-world environments like offices, homes, and more enables studies of people during more natural behaviors.
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Classification and Predictive Modeling
Connectivity (eg. functional, effective, structural) 2
Task-Independent and Resting-State Analysis
Novel Imaging Acquisition Methods:
NIRS 1
Keywords:
Cortex
Near Infra-Red Spectroscopy (NIRS)
NORMAL HUMAN
OPTICAL
Other - Scanning environment
1|2Indicates the priority used for review