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Daniel deLahunta
Vasilios Morikis
Dr. Hyle Park
Overview of OCT
High resolution, live imaging Subsurface features No preparation Used in many fields
Retinal imagingGastrointestinal imagingSkin imaging
Basic Working of OCT system Tissue sample is place under light
source Light is reflected back out Information about the tissue structure is
encoded in the reflected light Signal gets weaker with depth Resolution is on the order of
micrometers with up to several millimeters of imaging depth
Ultrasound
Optical coherence tomography
OCT uses an interferometer to detect the much shorter time delays between light signals
Interference fringes form when the reference and sample arm lengths are equal to within the coherence length of the light source
A depth profile (A-line) is obtained by detection of the interference pattern generated by light returning from the sample and reference arms as the length of the reference arm is scanned.
Optical coherence tomography
The intensity of interference patterns tells the reflectivity throughout the tissue
A 2D image (or 3D volume) is formed by scanning the beam laterally across the sample.
Polarization-sensitive OCT
Image of knuckle
Summer Projects Analyze data from previous system
Determine degree of inflammation in rat nerve after crushImprove predicted value of myelin thickness
Building of two new OCT systemsSet-up and calibration of reference and sample arms
Rat Nerve Inflammation Images previously taken Rat nerves were crushed and then imaged 1, 7,
14, 21, and 28 days after Purpose was to determine degree to which the
myelin regrows after injuryUseful for multiple sclerosis, blunt peripheral nerve
trauma
Day 1 data was unusable at the time due to large amount of inflammation
Determining Amount of Inflammation Use ImageJ Convert images to
binary Create new image with
white background and black where nerve is
Combine the two images
Inflammation is highlighted
Determine area of inflammation and total area
Inflammation results
21 22 23 24 25
control 0.062574 0.05196 0.0588 0.123366 0.053075
crush site 0.07585 0.097716 0.121422 0.145642 0.229792
Initial Data
Myelin measurements from intensity sensitive system
PS-OCT Slope from polarization sensitive system
Incorporation of Day 1
Still large amount of scatter in data Repeat inflammation process with other
days
Days 7,14, 21, and 28
Other Options
Compared control and crush site data by dividing crush site from control
Compared control and crush site data by subtracting crush site from control
Building of New Systems
Old 800 New 800 New 1310
Technique Intensity Polarization Polarization
Center wavelength 800 nm 800 nm 1310 nm
Depth scan rate 30,000/sec 144,000/sec 45,000/sec
Lateral resolution 6.5 μm 2.5 μm 6 μm
Vertical resolution 2 μm 1.5 μm 3 μm
Contributions
Galvanometer and control box
800 nm sample arm
Calibrated reference arm for both systems
Acknowlegdements Dr. Hyle Park,
Shahid, Yan, Erica, Christian, and the rest of the BIONIL research group
NSF, BRITE program, and Jun Wang