http://oilab.seas.wustl.edu -- 1

In Vivo Optical Coherent Tomography (OCT) and its Application for Brain Research

In Vivo Optical Coherent Tomography (OCT) and its Application for Brain Research

Vassiliy Tsytsarev

University of Maryland school of Medicine

E-mail: tsytsarev@umaryland.edu

http://oilab.seas.wustl.edu -- 2

Dependence of Tissue Penetration from Wavelengths Dependence of Tissue Penetration from Wavelengths Thickness of tissue probed:

30 m 100m 1mm 1cm 10cm

400 nm

800 nm

1600 nm

10 m

100 m

Intrinsic Optical Imaging (IOS)

THz imaging

???

2-Photon Microscopy

Diffuse Optical TomographyOptical

Coherence Tomography

Photoacoustic

http://oilab.seas.wustl.edu -- 3

Depth Penetration / Spatial ResolutionDepth Penetration / Spatial Resolution

Resolution (μm)

Dep

th P

enet

rati

on

(μ

m)

10

100

100

1000

10000

0.1 1.0 10 100 1000

2-Photon Microscopy

Intrinsic and Voltage-Sensitive Dye Optical Imaging (IOS)

FunctionalMagnetic Resonance Imaging (fMRI)

Optical Coherence Tomography (OCT)

http://oilab.seas.wustl.edu -- 4

Optical Coherent TomographyOptical Coherent Tomography

Broadband light source

Signal processing

Lateral scanning

Moving mirror

2x1 Coupler

2x2 Coupler

Computer

Basic principle:Back-reflected from the tissue light and the light produced by reference arm recombine within the 2 × 2 coupler

http://oilab.seas.wustl.edu -- 5

OCT: experimental setup OCT: experimental setup

Schematic of optical coherence tomography (OCT) and video microscopysystem. DCG, dispersion-compensating glass; TIA, transimpedance amplifier; BPF, bandpassfilter. Also shown is the forepaw stimulation protocol. Aguirre et al, Opt. Lett., 2006

http://oilab.seas.wustl.edu -- 6

OCT cortical functional brain imaging: experimental paradigm OCT cortical functional brain imaging: experimental paradigm

Precise registration of OCT imaging to the region of functional activation. The OCT scan is directed in the region of interest measured with video microscopy (A, B). Horizontal bars in B mark the activated and baseline time windows used to generate the functional map in A. Structural OCT imaging (C) visualizes the skull (S), surface vasculature (V), and meningeal layers, including the dura mater (D).

http://oilab.seas.wustl.edu -- 7

Functional OCT in the rat cortex. A fractional change map (A) demonstrates positive (warm colors) and negative (cool colors) changes in OCT signals during stimulation. Temporal sequences (B) reveal the presence of highly localized regions of activation in the cortex that persist throughout stimulation. The horizontal bars in D indicate the time windows used to generate the functional map (A, B, C).

http://oilab.seas.wustl.edu -- 8

Somatosensory cortex OCT functional imaging: forepaw stimulation

Somatosensory cortex OCT functional imaging: forepaw stimulation

Precise co-registration of OCT imaging to the region of functional activation. (A) The OCT scan is directed across the region of interest (indicated by blue double-headarrow) as measured with OISI. Anatomical features such as blood vessels (V) can be visualized in OISI and can be used to co-register with OCT image. (B) Structural OCT image reveals high-resolution visualization of the skull (S), surface vasculature (V), and meningeal layers, including the dura mater (D) and arachnoids (A). Cortex region (C) can also be visualized. (C) Three-dimensional rendering of the volume acquired by OCT. (D) En face OCT image reveals the characteristic blood vessel network which can be used to register the OCT imaging volume with OISI Y. Chen et al. / Journal of Neuroscience Methods 178 (2009)

http://oilab.seas.wustl.edu -- 9

OCT vs IOS: what is the signal base?OCT vs IOS: what is the signal base?

Spatial (right) and temporal OCT and IOS response structure

http://oilab.seas.wustl.edu -- 10

Forepaw OCT: temporal dynmicsForepaw OCT: temporal dynmics

Spatial-temporal evolution of functional OCT signals in the rat cortex. A fractional change map demonstrates the presence of positive (warm colors) and negative (cool colors) changes in OCT signals during stimulation. Functional OCT images at each individual temporal point (t = 1–15 s) reveal the presence of highly localized regionsof activation in the cortex that persist throughout stimulation. Bar: 500 mkm. Chen et al, 2009

http://oilab.seas.wustl.edu -- 11

Forepaw OCT imaging: crosectional vs frontal Forepaw OCT imaging: crosectional vs frontal

Integrated OCT signal in response to the forepaw electricalstimulation (Chen et al, 2006)

http://oilab.seas.wustl.edu -- 12

Optical Coherent Tomography of the Epileptic SeizuresOptical Coherent Tomography of the Epileptic Seizures

EEG

10 s / 2 mV

http://oilab.seas.wustl.edu -- 13

Thank you very much for your attention Thank you very much for your attention