IVUS Reflector Visualization Using Harmonic Frequency Separation
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Solution Overview
Problem
Conventional intravascular ultrasound (IVUS) images struggle to adequately depict features like stents and calcium deposits, making it challenging to distinguish them from vessel walls, which affects diagnostic accuracy.
Innovation Solution
A system and method that processes both linear and nonlinear ultrasound reflections by applying different bandpass filters to generate separate images, allowing for the visualization of nonlinear reflectors such as stents and calcium deposits by generating harmonic frequencies, and overlays these images on a combined display to enhance identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional B-mode IVUS imaging is used to visualize blood vessel features, then the imaging system maintains simplicity and broad compatibility, but the ability to adequately depict and distinguish nonlinear reflectors such as stents and calcium deposits from other vessel wall features is insufficient
Solution Approach 1:
The ultrasound signal processing is segmented into separate frequency band processing paths. A first processing path handles linear reflections at the transmit frequency, while a second processing path handles nonlinear reflections at different frequencies. This segmentation allows each path to be optimized for its specific purpose without increasing overall system complexity, as the segmentation occurs in the signal processing domain rather than requiring additional hardware components.
Solution Approach 2:
The patent introduces a frequency dimension to the traditional IVUS imaging approach. By analyzing ultrasound reflections at multiple frequency bands (the original transmit frequency and harmonic frequencies), the system creates an additional discrimination dimension. This allows nonlinear reflectors to be distinguished from linear reflectors based on their frequency response characteristics, effectively adding a new dimension of information without requiring physical modification of the imaging catheter or transducer.
2Reliability
If conventional IVUS imaging processes all ultrasound reflections uniformly, then the processing workflow remains simple, but the confidence in identifying and locating nonlinear reflectors is reduced
Solution Approach 1:
The signal processing workflow is segmented into distinct processing paths for linear and nonlinear reflections. Each path applies appropriate processing techniques optimized for its specific signal characteristics. This segmentation improves reliability by ensuring that nonlinear reflectors are processed with techniques specifically designed to enhance their visibility and characterization, rather than being lost in uniform processing of all reflections.
Solution Approach 2:
The patent introduces frequency band filtering as an intermediary step between ultrasound signal acquisition and image formation. Bandpass filters act as intermediaries that selectively pass specific frequency ranges corresponding to linear or nonlinear reflections while blocking others. This intermediary processing stage enables reliable identification of nonlinear reflectors by isolating their characteristic frequency signatures before further processing and image generation.
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
Improves diagnostic confidence by clearly distinguishing nonlinear reflectors like stents and calcium deposits from linear structures, enhancing the accuracy of intraluminal imaging.
Implementation Method 1
The transducers emit ultrasonic energy in order to create an image of the vessel of interest. Ultrasonic waves are partially reflected by discontinuities arising from tissue structures (such as the various layers of the vessel wall), red blood cells, and other features of interest. Echoes from the reflected waves are received by the transducer
Implementation Method 2
Calcium deposits and stents may be considered nonlinear reflectors, as they tend to reflect ultrasound energy in a nonlinear fashion. In nonlinear reflections, the frequencies of the echoes reflected by an object are different from the frequencies emitted by the ultrasound transducer. When imaged with sufficient acoustic intensity, nonlinear reflectors such as calcium deposits and stents generate nonlinear reflections that include harmonic frequencies of the frequencies transmitted by the ultrasound transducer
Data Source
AI summary
Systems, methods, and devices for visualizing a reflector in a lumen of a patient are provided. In one embodiment, a system for visualizing a reflector includes an intraluminal ultrasound imaging catheter in communication with a processor circuit. The processor circuit is configured to receive, from the intraluminal ultrasound imaging catheter, ultrasound image signals representative of the lumen and the reflector, generate first ultrasound image data based on the ultrasound image signals, generate second ultrasound image data based on a portion of the ultrasound image signals associated with a second frequency different from the transmit frequency, and output a visualization based on the first and second ultrasound image data to a display. In some aspects, the visualization may serve to identify and distinguish nonlinear reflectors from linear reflectors in the combined image.