The document discusses optical coherence tomography (OCT) which uses light rather than ultrasound to image tissues. It provides the following key points: 1. OCT emits light pulses into tissue and analyzes the intensity and depth of backscattered light to characterize tissues based on reflectivity and attenuation. 2. OCT provides higher resolution imaging of around 15-20 microns, around 10 times higher than intravascular ultrasound (IVUS), allowing detailed views of intraluminal structures. 3. A limitation is its shallow penetration of around 1.5-2 mm, providing less definition of deep regions like lipid-rich plaques, requiring blood to be displaced for clear imaging.

1. “The same concept than IVUS, but using light rather than ultrasound”
 Emission of light pulses and reception of the fraction backscatterd by the tissue
 Analysis of the intensity of the signal and depht that light penetrates in the tissue
Int
Prof
¿How it works?
Theoretical basis

2. Introduction
What are the optical properties that we use to characterize tissues?
 “Reflectivity”: Bright, signal intensity
 Attenuation: determines the depth of light into the tissue

3. Image acquisition
Blood is a non-transparent media. For
this reason it´s neccesary to displace
blood from the lumen during image
acquisition.
Techniques:
 Occlusive: Inflation of low compliant occlussion balloon proximal to the
target lesion and injection of saline through the lumen of the balloon.
 Non occlussive: Injection of dye through the guiding catheter.
Brezinski ME et al. Intern J Cardiol 2006;107:154-65
Tomlins PH et al. J. Phys D: Appl Phys 2005;38:2519-35
Pinto TL et al. J Intervent Cardiol 2006;19:566-73
Yamaguchi T et al. Am J Cardiol 2008;101:562-67
Tanigawa J et al. Eurointerv 2007;3:128-36
Prati F et al. Eurointerv 2007;3:365-70
Blood

4. Axial resolution 15-20 microns (0.015-0.02 mm)
Main advantage: HIGH RESOLUTION
Introduction
OCT is near of celular range resolution
Ten folds higher
resolution than IVUS

5. Advantage: Highly detailed imaging of intraluminal structures,
interface plaque-lumen and superficial portions of vessel wall
Introduction

6. ¿Where is the external vessel border?
Disadvantages:
 Limited penetration (1.5 - 2
mm). Poor definition of deep
regions, specially in lipid-rich
plaques, positive remodeling
 Interference with blood: Need
of “flushing”
Introducción

7. Jang IK et al. JACC 2002;39:604-9 Rieber J et al. Coron Art Dis 2006;17:425-30
Stamper D et al. JACC 2006;47:C69-79 Kawasaki M et al. JACC 2006;48:81-8
 Fibrotic plaque: Hiperintense,
homogeneous, low atenuation
 Lipid-rich plaque (necrotic core):
Hipointense, high atenuation, diffuse
borders
 Calcified plaque: Hipointense, mid
atenuation, sharp borders
Coronary lesions
OCT morphology of
coronary plaques

8. Fibrotic plaques
Coronary lesions
Hiperintense, homogeneous, low attenuation (high penetration)

9. Calcified plaques
Hipointense, mid attenuation, well-defined, sharp borders
Coronary lesions

10. Coronary lesions
Calcified plaques
Hipointense, mid attenuation, well-defined, sharp borders

11. Hipointense, high atenuation (low penetration), diffuse borders
Lipid-rich plaques/necrotic core
Coronary lesions

12. Thin-cap fibroatheroma
OCT is the unique technique available in daily practice that allows
accurate measurement of fibrous cap thickness.
Previous pathological studies have identified 65 microns thickness as the threshold
of high risk for plaque rupture
Coronary lesions