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Optical Coherence Tomography (OCT)

Daniel deLahunta Vasilios Morikis Dr. Hyle Park. Optical Coherence Tomography (OCT). Overview of OCT. High resolution, live imaging Subsurface features No preparation Used in many fields Retinal imaging Gastrointestinal imaging Skin imaging. Basic Working of OCT system.

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Optical Coherence Tomography (OCT)

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  1. Daniel deLahunta Vasilios Morikis Dr. Hyle Park Optical Coherence Tomography (OCT)

  2. Overview of OCT • High resolution, live imaging • Subsurface features • No preparation • Used in many fields • Retinal imaging • Gastrointestinal imaging • Skin imaging

  3. 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

  4. Ultrasound

  5. 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.

  6. 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.

  7. Polarization-sensitive OCT Image of knuckle

  8. Summer Projects • Analyze data from previous system • Determine degree of inflammation in rat nerve after crush • Improve predicted value of myelin thickness • Building of two new OCT systems • Set-up and calibration of reference and sample arms

  9. 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 injury • Useful for multiple sclerosis, blunt peripheral nerve trauma • Day 1 data was unusable at the time due to large amount of inflammation

  10. 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

  11. Inflammation results

  12. Initial Data • Myelin measurements from intensity sensitive system • PS-OCT Slope from polarization sensitive system

  13. Incorporation of Day 1 • Still large amount of scatter in data • Repeat inflammation process with other days

  14. Days 7,14, 21, and 28

  15. 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

  16. Building of New Systems

  17. Contributions • Galvanometer and control box • 800 nm sample arm • Calibrated reference arm for both systems

  18. Acknowlegdements • Dr. Hyle Park, Shahid, Yan, Erica, Christian, and the rest of the BIONIL research group • NSF, BRITE program, and Jun Wang

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