Synopsis

Diffuse optical imaging (DOI) is a portable imaging modality that provides the ability to perform early and continuous monitoring of brain function. Its portability overcomes many of the technical and logistical challenges of performing MRI investigations in hospitalized patients. While standard DOI systems suffer from low spatial resolution and lack of brain specificity, new developments in hardware and software have overcome many of these technical limitations. In this talk, I will introduce novel DOI techniques developed for bedside mapping of resting-state functional connectivity in neonates and adults and present multi-modal comparisons with functional MRI maps obtained in the same subjects.

Target audience

Outcome/Objectives

• To describe novel diffuse optical imaging (DOI) methods for bedside, portable and wearable functional neuroimaging.
• To describe resting-state functional connectivity mapping techniques with DOI and compare with functional MRI correlates.
• To introduce resting-state functional connectivity DOI applications in adults, neonates and hospitalized patients.

Methods

Different imaging methods will be discussed in this course.

1. High-density diffuse optical tomography (HD-DOT) techniques improve spatial resolution and brain specificity by using high-density arrays of overlapping measurements (1, 2). I will describe recent advances in DOT techniques that allows to map distributed brain function and networks in adults (3).
2. Realistic head modeling methods are needed for co-registering DOT functional maps to reference anatomy and/or within subjects. In this part of the course, I will describe anatomical head modeling methods based on subject-specific anatomical MR images as well as age-specific atlases (4). Spatial normalization methods for group analysis will be also presented.
3. DOT techniques have been recently extended to clinical situations to perform bedside functional mapping. Resting-state functional connectivity MRI (rs-fMRI) methods are particularly suited for studying infants who cannot perform complex tasks (5, 6). In the last part of this course, I will describe a portable HD-DOT system for simultaneous resting-state functional connectivity DOT mapping of multiple functional regions in healthy and hospitalized neonates (7, 8, 9). Voxel-wise comparisons with rs-fMRI maps obtained in the same population will also be presented.

Acknowledgements

References

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2. Zeff BW, White BR, Dehghani H, Schlaggar BL and Culver JP. Retinotopic mapping of adult human visual cortex with high-density diffuse optical tomography. PNAS 2007; 104:12169-74.
3. Eggebrecht AT, Ferradal SL, Robichaux-Viehoever A, Hassanpour MS, Dehghani H, Snyder AZ, Hershey T and Culver JP. Mapping distributed brain function and networks with diffuse optical tomography. Nat Photonics 2014; 8(6):448-454.
4. Ferradal SL, Eggebrecht AT, Hassanpour M, Snyder AZ and Culver JP. Atlas-based head modeling and spatial normalization for high-density diffuse optical tomography: in vivo validation against fMRI. Neuroimage 2014; 85:117-26.
5. Smyser CD, Inder TE, Shimony JS, Hill JE, Degnan AJ, Snyder AZ and Neil JJ. Longitudinal analysis of neural network development in preterm infants. Cereb Cortex 2010; 20(12):2852-62.
6. Doria V, Beckmann CF, Arichi T, Merchant N, Groppo M, Turkheimer FE, Counsell SJ, Murgasova M, Aljabar P, Nunes RG, Larkman DJ, Rees G and Edwards AD. Emergence of resting state networks in the preterm human brain. PNAS 2010; 107(46):20015-20.
7. White BR, Liao SM, Ferradal SL, Inder TE and Culver JP. Bedside optical imaging of occipital resting-state functional connectivity in neonates. Neuroimage 2012; 59(3):2529-38.
8. Liao SM, Ferradal SL, White BR, Gregg N, Inder TE and Culver JP. High-density diffuse optical tomography of term infant visual cortex in the nursery. J Biomed Opt. 2012; 17(8):081414.
9. Ferradal SL, Liao SM, Eggebrecht AT, Shimony JS, Inder TE, Culver JP and Smyser CD. Functional Imaging of the Developing Brain at the Bedside Using Diffuse Optical Tomography. Cereb Cortex 2016; 26(4):1558-68.