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