1.7 μm Swept Laser OCT for Deep Lipid Pool Visualization
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Solution Overview
Problem
Conventional intravascular optical coherence tomography (OCT) devices face challenges in visualizing large lipid pools due to limited depth penetration, necessitating the use of intravascular ultrasound for identifying atherosclerotic plaques, which compromises spatial resolution and imaging quality.
Innovation Solution
An OCT system employing a 1.7 μm swept laser source within the lipid absorption spectrum, allowing for higher sensitivity and deeper tissue penetration, enabling visualization of large lipid pools while maintaining high spatial resolution through the use of a combined 1.3 μm/1.7 μm system that calculates intensity ratios for molecular contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional IVOCT devices with 1.3 μm swept source laser are used, then spatial resolution of ~15 μm is achieved, but depth penetration is limited and large lipid pools cannot be visualized
Solution Approach 1:
The patent changes the wavelength parameter of the laser source from conventional 1.3 μm to 1.7 μm, which falls within the lipid absorption spectrum. This parameter change enables deeper tissue penetration while maintaining spatial resolution, allowing visualization of large lipid pools that were previously invisible to conventional IVOCT devices.
2Length of stationary object
If intravascular ultrasound (IVUS) is used to identify large lipid pools, then imaging depth of ~7 mm is achieved, but spatial resolution deteriorates to ~150 μm
Solution Approach 1:
The patent changes the imaging modality from ultrasound to optical domain by using 1.7 μm swept source OCT. This enables achieving both deep imaging depth (comparable to IVUS) and high spatial resolution (maintaining OCT's ~15 μm resolution), thereby resolving the trade-off between depth and resolution that plagues IVUS imaging.
3Length of stationary object
If 1.7 μm wavelength is used in the presence of water/blood, then sensitivity and depth penetration are improved, but signal strength typically decreases due to strong absorption
Solution Approach 1:
The patent converts the harmful effect of water/blood absorption at 1.7 μm into a beneficial contrast mechanism. By operating within the lipid absorption spectrum, the system exploits differential absorption between lipid and non-lipid tissues, allowing lipid pools to appear with high contrast despite the presence of absorbing media like blood and water.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The 1.7 μm OCT system effectively differentiates plaque from normal tissue, provides high molecular contrast, and achieves improved sensitivity for identifying lipid types and collagen, overcoming limitations of conventional systems by offering deeper penetration and maintaining spatial resolution.
Implementation Method 1
a swept laser source with a wavelength in a lipid absorption spectrum... the lipid absorption spectrum ranges from about 1.65 to 1.8, and an exemplary wavelength is about 1.7 μm
Implementation Method 2
intravascular optical coherence tomography (IVOCT) offers a superior spatial resolution of ~15 μm
Data Source
AI summary
An OCT system with a swept light source centered around 1.7 μm for identifying atherosclerotic plaque and visualization of large lipid pool is provided. Advantages for using the 1.7 μm swept source laser include higher contrast between lipid and normal tissue and deeper penetration of the optical signals from the 1.7 μm swept source laser into the tissue. With deeper penetration into the tissue, more structural information from deep within the tissue is obtained. The present invention also features multimodality imaging systems that integrate additional imaging systems into the OCT system at 1.7 μm. As an example, an integrated 1.3 μm and 1.7 μm OCT system is provided which simultaneously generates OCT images using both the OCT systems which are used to characterize and differentiate the types of tissue.