Computer signal transmission in optical coherence tomography on the basis of Wigner transformation JASS-2004, JASS-2004, St.-Petersburg St.-Petersburg

Why Use OCT?  For more than three centuries, the microscope has been considered the ultimate tool to understand the origins of disease by examining tissue and microstructures in exquisite detail.

Why use OCT?  While the technology contained within the microscope has evolved over time, enabling better resolution of smaller structures, one aspect has remained constant - material to be examined must be excised from the body and brought to the microscope.

2 main reasons  New thinking concerning the origins of the world's two largest killers –  heart disease and cancer –  expose the limitations of the current paradigm. Both diseases are thought to originate at the cellular level in the thin ( micron) cellular layer covering the inner and outer surfaces of the body. Understanding these diseases on the microscopic level on an in vivo basis could lead to better diagnosis, earlier more precise treatments and development of novel therapies to help eradicate these diseases

microscopic images from within the body  For years, scientists, physicians and technology developers have struggled to achieve microscopic images from within the body. These attempts have met with limited success due to two primary factors: 1. the size of the apparatus being deployed and 2. the resolution of the images being obtained.

Attempts to obtain microscopic images using external methodologies:  magnetic resonance,  X-ray, ultrasound, and  nuclear imaging, have met with similar fates. have met with similar fates.

A New Weapon for Heart Disease and Cancer  While OCT has the potential to be used for a variety of medical applications, cancer and heart disease represent two of the most pressing, and promising application areas.

Cardiovascular Imaging  OCT imaging has the potential to improve current cardiovascular therapies such as stenting and balloon angioplasty, by providing vascular images in real time to guide stent placement and balloon inflation. Given its small size, the OCT imaging guidewire could be integrated into an existing therapeutic catheter or deployed alongside during a procedure.

 New cardiac research indicates that unstable plaques - arterial lesions that do not constrict the blood vessel but rather burst releasing a bolus of lipids into the blood stream - may be responsible for up to 70 percent of all heart attacks. OCT has the potential to clearly identify plaques and help differentiate unstable plaques from stable plaques.  Cardiovascular System Atherosclerotic Disease Brezinski, M.E. Circ. 93; 1206:1996

 In addition to providing exquisite morphological detail, OCT is meeting other capabilities such as spectroscopic imaging, polarization imaging and Doppler to provide further information regarding tissue composition and flow.

Cancer Detection  It is estimated that more than 85 percent of all cancers originate in the epithelium, the thin ( micron) cellular layer covering the inner and outer surfaces of the body. Excisional biopsy, removing tissue from the body and examining it under a microscope, is the gold standard for cancer diagnosis. However, many biopsies are done on a hit or miss basis, small pieces of tissue are excised at random and dissected to check for cancerous cells.

 OCT has the potential to greatly improve conventional biopsy by more precisely identifying the areas to be excised based on images of the epithelial layers, reducing the number of biopsies and making earlier and more accurate diagnosis possible. As the technology matures, it may be possible to perform biopsies using OCT imaging alone, making possible point of care biopsy.

Microscopy  OCT offers the potential to assist in the visualization of vessels and nerves for repair surgery. OCT may also have the potential for identifying the margins of low-grade invasive neurological tumors. The use of OCT imaging forceps may be beneficial to many microsurgical procedures. Intestinal polyps Ex Vivo Human Tissue

What is OCT? Optical Coherence Tomography (OCT) is a promising new class of diagnostic medical imaging technology that utilizes advanced photonics and fiber optics to obtain images and tissue characterization on a scale never before possible within the human body.

When fully exploited, the technology has the potential to dramatically change the way physicians, researchers and scientists see and understand the human body in order to better diagnose and treat disease.

OCT and Ultrasound  Simply put, OCT combines the principles of ultrasound with the imaging performance of a microscope and a form factor that is familiar to clinicians.  Whereas ultrasound produces images from backscattered sound "echoes,"  OCT uses infrared light waves that reflect off the internal microstructure within the biological tissues. The frequencies and bandwidths of infrared light are orders of magnitude higher than medical ultrasound signals -- resulting in greatly increased image resolution times greater than any existing modality.

Comparison between OCT (left) and Ultrasound (right). Comparison between OCT (left) and Ultrasound (right). Tearney, G.J., et. al. Circ. 4256, 1997

Методы описания сигналов в ОКТ  Infrared light is delivered to the imaging site through a single optical fiber only.006" diameter (about the size of the period in this sentence). The imaging guidewire contains a complete lens assembly to perform a variety of imaging functions. The guidewire can be deployed independently or integrated into existing therapeutic or imaging catheters

Electronic and interferometric techniques  While standard electronic techniques are adequate for processing ultrasonic echoes that travel at the speed of sound, interferometric techniques are required to extract the reflected optical signals from the infrared light used in OCT.  The output, measured by an interferometer, is computer processed to produce high-resolution, real time, cross sectional or 3-dimensional images of the tissue. This powerful technology provides in situ images of tissues at near histological resolution without the need for excision or processing of the specimen.

 In addition to providing high-level resolutions for the evaluation of microanatomic structures OCT is inherently able to provide information regarding tissue composition. Using spectroscopy, users can evaluate the spectral absorption characteristics of tissue while simultaneously determining the orderliness of the tissue through the use of polarization imaging

Advantages of OCT  HIGH RESOLUTION: Current OCT systems have resolutions at 4-20 um compared to 110 um for high frequency ultrasound.  TISSUE CHARACTERIZATION: Using information inherent to the returning photon signals, OCT can perform both spectroscopic and polarization imaging to better evaluate the composition of tissues and lesions.

Advantages of OCT  SMALL SIZE: The fiber-based design allows easy integration with small catheter/endoscopes.  REAL TIME IMAGING: Imaging is at or near real time.  DOPPLER IMAGING: Capable of simultaneous imaging and real time flow measurements.

Wigner transformation

Model 1 The first model is a cos-function with gaussian

Wigner transformation of 2 signals with different parameters (Re)

Wigner transformation of 2 signals with same parameters (Re)

Wigner transformation of 2 signals with different parameters (Im)  ПВ двух КФГО сигналов с разными параметрами (мнимая часть) как правило обнуляется

Model 2 Signal – Linear frequency modulation

Wigner transformation of 2 signals with same parameters (Re)

Wigner transformation of 2 signals with different parameters (Re)

Wigner transformation of 2 signals with different parameters (Im)

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