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Optical Coherence Tomography What it is and How it Works.

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Presentation on theme: "Optical Coherence Tomography What it is and How it Works."— Presentation transcript:

1 Optical Coherence Tomography What it is and How it Works

2 What is Intravascular OCT? An optical imaging modality that uses near-infrared light for high-resolution imaging of vessel anatomy, tissue microstructure and stents. Key Features:  Uses light, not sound  Does not use X-ray  Image acquisition is fast  Images acquired are sharp, detailed and easy to interpret 2 Images: Drs. Grube, Buellesfeld, Guerkens and Mueller, Helios Heart Center, Siegburg, Germany Image: Image: Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

3 OCT Technology from St. Jude Medical  Console  Rapid exchange (Rx) imaging catheter  Contrast flush; balloon occlusion not required  Fast image acquisition: 5 cm pullback in 2.5 sec 3

4 Image Display Cross-sectional View Longitudinal View 4

5 Markers 20 mm apart Pullback length: 5 cm Lens Dragonfly ™ Imaging Catheter  Optical fiber core  2.7 F  x 135 cm usable length  Rapid exchange  Fits 0.014" guidewire  Used with 6-7 F guide catheter  Radiopaque markers 5

6 How Does OCT Work?  Optical fiber inside catheter spins around to create a radar-style image 6

7 Image Generation – Pullback  As the fiber pulls back to map a vessel segment, a 5 cm long spiral scan is created  One pullback = approximately 270 frames 7

8 Image Generation  Light emitted by the optical fiber is reflected back by different types of tissue  The system measures the time delay of the reflected light waves  An OCT image is generated showing vessel anatomy and tissue microstructure 8 axial lateral catheter guidewire shadow optical fiber Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

9 Physics of OCT Interference of Light Waves 9 Constructive Interference Destructive Interference

10 Time vs. Frequency Domain Intravascular OCT Time Domain OCT (TD-OCT):  Commercially available for cardiovascular use 2001-present  Moderate image quality  Slow imaging  Requires occlusion balloon Frequency Domain OCT (FD-OCT):  Commercially available for cardiovascular use present  Exceptional image quality  Fast imaging: x increase in speed  Rapid contrast flush instead of balloon occlusion 10 C7-XR system: FD-OCT 100 fps, 20 mm/s pullback M3 system: TD-OCT 20 fps, 1 mm/s pullback Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

11 Frequency Domain OCT Multiple terms are used to describe the same type of OCT imaging, but there is no fundamental difference between these methods. St. Jude Medical:Frequency Domain OCTFD-OCT Terumo, MGH: Optical Frequency Domain Imaging OFDI Volcano:High Definition OCTHD-OCT Others:Swept Source OCTSS-OCT Fourier Domain OCTFD-OCT 11 Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

12 What Determines System Performance? (1/3) ParameterDeterminesControlled ByC7-XR Value Imaging Speed  Acquisition time  Required flush volume  Laser sweep rate  Catheter rotation rate  Pullback speed 50,000 axial lines/s 100 Hz 20 mm/s Sensitivity  Minimum detectable tissue reflection  Image contrast  Electrical and optical system design Better than 100 db Imaging Range  Maximum vessel diameter  Laser line width  Electrical and optical system design 10 mm (in contrast) Resolution  Minimum detectable tissue feature  Speckle size and image granularity  Laser tuning range (axial)  Catheter focusing optics (lateral) 15 µm (axial) 20 – 40 µm (lateral) Tissue Penetration  Visible depth into vessel wall  Scattering and absorption of tissue 1 – 2 mm Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis)

13 What Determines System Performance? (2/3) ParameterDeterminesControlled ByC7-XR Value Imaging Speed  Acquisition time  Required flush volume  Laser sweep rate  Catheter rotation rate  Pullback speed 50,000 axial lines/s 100 Hz 20 mm/s Sensitivity  Minimum detectable tissue reflection  Image contrast  Electrical and optical system design Better than 100 dB Imaging Range  Maximum vessel diameter  Laser line width  Electrical and optical system design 10 mm (in contrast) Resolution  Minimum detectable tissue feature  Speckle size and image granularity  Laser tuning range (axial)  Catheter focusing optics (lateral) 15 µm (axial) 20 – 40 µm (lateral) Tissue Penetration  Visible depth into vessel wall  Scattering and absorption of tissue 1 – 2 mm 13 Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

14 What Determines System Performance? (3/3) ParameterDeterminesControlled ByC7-XR Value Imaging Speed  Acquisition time  Required flush volume  Laser sweep rate  Catheter rotation rate  Pullback speed 50,000 axial lines/s 100 Hz 20 mm/s Sensitivity  Minimum detectable tissue reflection  Image contrast  Electrical and optical system design Better than 100 dB Imaging Range  Maximum vessel diameter  Laser line width  Electrical and optical system design 10 mm (in contrast) Resolution  Minimum detectable tissue feature  Speckle size and image granularity  Laser tuning range (axial)  Catheter focusing optics (lateral) 15 µm (axial) 20 – 40 µm (lateral) Tissue Penetration  Visible depth into vessel wall  Scattering and absorption of tissue 1 – 2 mm 14 Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

15 Performance Comparison: FD-OCT vs. TD-OCT 15 C7-XRM3M2 Axial Resolution15 – 20 µm Beam Width20 – 40 mm Frame Rate100 frames/s20 frames/s15 frames/s Pullback Speed20 mm/s1.5 mm/s1 mm/s Max. Scan Dia.10 mm6.8 mm Tissue Penetration mm Lines per Frame Lateral Sampling (3 mm Artery) 19 µm39 µm Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

16 C7-XRIVUS Axial Resolution15 – 20 µm100 – 200 µm Beam Width20 – 40 mm200 – 300 mm Frame Rate100 frames/s30 frames/s Pullback Speed20 mm/s mm/s Max. Scan Dia.10 mm15 mm Tissue Penetration mm10 mm Lines per Frame Lateral Sampling (3 mm Artery)19 µm 225  µm Blood ClearingRequiredNot Required Performance Comparison: FD-OCT vs. IVUS 16 Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

17 OCT Technical Terms Pixel: Like a photograph, each image consists of lines and pixels. Each pixel is approximately 5x19 microns. Line: Each frame consists of 500 rotational lines. The greater the number of lines per frame, the finer the texture of the image. Frame: The optical fiber spins around to form a frame. Frame rate: Frame rate is the number of cross-sectional frames that can be acquired over a given period of time. Axial: Axial is the direction that is parallel to the optical beam in an OCT system. The axial resolution of OCT is 15 µm. Each axial line consists of 1024 pixels. Lateral: Lateral is the direction perpendicular to the optical beam in an OCT system. The lateral resolution of the C7-XR system is 20–40 µm, depending on the distance away from the catheter. Optical resolution: A measure of the smallest physical feature that can be detected with an imaging system. Measured in units of millimetres (mm) or micrometers (microns, µm). One mm is equal to one thousand µm. A piece of paper is about 90 µm thick, while a human red blood cell is about 10 µm long. The optical resolution of OCT is approximately 15 µm axial by µm lateral, depending on how far the tissue is away from the center of the catheter. Hertz: Frame rate is measured in units of Hertz (Hz). The optical fiber rotates at 20 Hz during preview mode (= 20 frames/second), and rotates at 100 Hz (= 100 frames/second) during high-speed pullback. The C7-XR system acquires 50,000 axial image lines per second. This is sometimes abbreviated by saying that it is “a 50 kHz system.” 17

18 OCT Technology: Key Concepts to Remember  OCT uses reflected light waves to image coronary arteries in microscopic detail.  The latest FD-OCT is faster, the images are better, and it does not require balloon occlusion.  The latest technology from St. Jude Medical scans a 5 cm segment of an artery in less than 3 seconds.  As a result of its resolution and speed, OCT produces clear, easy-to-understand views of vessel morphology and plaque composition for planning and optimizing treatment. 18 Gonzalo N. Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response After Stent Implantation (Thesis) 2010

19 RX Only Please review the Instructions for Use prior to using these devices for a complete listing of indications, contraindications, warnings, precautions, potential adverse events, and directions for use. Product referenced is approved for CE Mark. Unless otherwise noted, ™ indicates a registered or unregistered trademark or service mark owned by, or licensed to, St. Jude Medical, Inc. or one of its subsidiaries. GOLDEN IMAGE, the color Gold, Dragonfly, ST. JUDE MEDICAL, the nine-squares symbol and MORE CONTROL. LESS RISK. are registered and unregistered trademarks and service marks of St. Jude Medical, Inc. and its related companies. ©2010 St. Jude Medical, Inc. All rights reserved. 19


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