Intravascular Ultrasound Transducer Multi-Frequency Imaging
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Solution Overview
Problem
Current intravascular ultrasound (IVUS) systems have inadequate contrast and spatial resolution to accurately assess vulnerable plaques and stent healing, struggling to characterize thin-cap fibroatheromas and neointima, and require complex multi-frequency imaging that increases system and catheter complexity and cost.
Innovation Solution
A novel IVUS system employing pulse compression and frequency compounding techniques with a single-transducer catheter and image processor, using a coded pulser to emit multi-frequency waveforms and decompose reflected signals into subband signals for enhanced imaging, allowing for high contrast and spatial resolution without the need for co-registration of multiple images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transducer frequency is increased to improve spatial resolution, then spatial resolution is improved, but contrast resolution deteriorates due to reduced contrast between blood and non-blood tissue and higher tissue attenuation
Solution Approach 1:
The system employs multi-frequency periodic pulsing where the transducer is excited at multiple discrete frequencies in a periodic sequence. Each frequency component is processed separately and then combined through frequency compounding to achieve both high spatial resolution and maintained contrast resolution by utilizing the frequency-dependent acoustic properties of different tissues
Solution Approach 2:
The system changes the operating frequency parameter dynamically by transmitting ultrasound at multiple discrete frequencies rather than a single frequency. This allows exploitation of frequency-dependent attenuation characteristics where lower frequencies provide better penetration and contrast while higher frequencies provide better spatial resolution, and the combined effect achieves both goals simultaneously
2Adaptability or versatility
If multiple transducers are used to achieve multi-frequency imaging, then imaging frequency range is improved, but device complexity and cost increase
Solution Approach 1:
A single ultrasound transducer is designed to perform multiple functions by being excited at multiple discrete frequencies. The transducer serves as both a broadband transmitter and receiver, eliminating the need for multiple specialized transducers while achieving multi-frequency imaging capability through electronic frequency switching and signal processing
Solution Approach 2:
Multiple frequency components are merged into a single imaging channel through frequency compounding. The system combines the information from multiple discrete frequency transmissions into one unified image, replacing what would traditionally require multiple separate transducer systems with a single integrated transducer and processing system
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 system achieves improved assessment of coronary arteries with higher contrast and spatial resolution, enabling better visualization of vulnerable plaques and stent healing, while maintaining system simplicity and cost-effectiveness.
Implementation Method 1
The ultrasound transducer may be configured to emit ultrasound energy towards the target blood vessel while rotating about the longitudinal axis of the catheter. The ultrasound transducer may be further configured to receive the ultrasound energy reflected by the target vessel
Implementation Method 2
The imaging assembly may include a piezoelectric transducer located generally at or close to the distal end of the catheter
Implementation Method 3
The imaging assembly may include a piezoelectric transducer located generally at or close to the distal end of the catheter, which may be energized by one or more electrical conduits
Data Source
AI summary
Disclosed is a high resolution intravascular ultrasound imaging system including a catheter with a rotatable imaging assembly and an image processor. The image processor in turn features a pulser configured to energize the ultrasound transducer of the rotatable imaging assembly with a multi-frequency ultrasound waveform signal. The image processor further contains a receiver configured to decompose received ultrasound energy as reflected by the target vessel into a plurality of individual subband signals, individually process these signals and reconstitute these signals into a high resolution image of the blood vessel. The IVUS system of the invention may be useful in characterizing cap thickness of vulnerable plaques or other detailed studies of blood vessels.