PMUT Tilt Angle for Doppler IVUS Blood Flow
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Solution Overview
Problem
Current intravascular ultrasound (IVUS) imaging systems face challenges in distinguishing moving blood from stationary tissue or thrombi, particularly at higher frequencies, and are not well-suited for Doppler color flow imaging due to the difficulty in achieving the required transducer tilt angle for polymer piezoelectric micromachined ultrasound transducers (PMUTs) in rotational IVUS catheters.
Innovation Solution
A polymer piezoelectric micromachined ultrasonic transducer and rotational IVUS catheter configuration that facilitates Doppler color flow imaging by mounting the transducer at a substantial tilt angle, enabling the collection of Doppler ultrasound blood flow data and enhancing image quality through velocity-encoded color overlays, automated border detection, and thrombus differentiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a polymer piezoelectric micromachined ultrasound transducer (PMUT) is used in a rotational IVUS catheter, then the transducer can be mounted at a substantial tilt angle to enable Doppler color flow imaging, but the PMUT requires active electronics (amplifier circuit) closely coupled to the transducer which increases device complexity
Solution Approach 1:
The patent combines the PMUT transducer with its amplifier circuit into an integrated assembly where the electronics are closely coupled to the transducer. This merging allows the tilt-angle configuration needed for Doppler imaging while managing the complexity through integrated design rather than separate components.
Solution Approach 2:
The patent mounts the PMUT at a substantial tilt angle relative to the catheter axis, transitioning from conventional axial mounting to an angled configuration. This dimensional change enables the ultrasound beam to be directed at angles that facilitate Doppler color flow imaging while the integrated electronics follow the transducer in this tilted orientation.
2Manufacturing precision
If the ultrasound frequency is increased to improve resolution, then image quality improves, but the contrast between blood echoes and vessel wall tissue echoes diminishes
Solution Approach 1:
The patent introduces Doppler velocity information as an intermediary parameter to distinguish blood from tissue. By measuring blood flow velocity and encoding it as color overlays or other visual distinctions, the system compensates for the reduced echo contrast at high frequencies, allowing clear differentiation between moving blood and stationary tissue even when traditional echo intensity contrast is diminished.
3Adaptability or versatility
If a conventional IVUS transducer configuration is used, then the structure is simple, but the system cannot perform Doppler color flow imaging to distinguish moving blood from stationary thrombi
Solution Approach 1:
The patent configures the PMUT to rotate within the catheter assembly, enabling dynamic measurement of blood flow velocity through Doppler shifting. This dynamic mounting arrangement allows the system to distinguish moving blood from stationary thrombi by detecting motion, while the rotational mechanism integrates with the existing IVUS catheter structure to minimize added complexity.
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
This configuration improves the differentiation between moving blood and stationary tissue, facilitates quantitative blood flow estimation, and extends the dynamic range of IVUS signals, leading to better diagnostic accuracy and image quality in IVUS imaging.
Implementation Method 1
a polymer piezoelectric micromachined ultrasonic transducer
Implementation Method 2
receives the reflected ultrasound echoes
Implementation Method 3
they are partially reflected from discontinuities arising from tissue structures
Implementation Method 4
measuring the blood flow velocity within the vessel
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4D
AI summary
Rotational intravascular ultrasound (IVUS) imaging devices, systems, and methods are provided. Some embodiments are directed to transducer mounting configurations that enable polymer piezoelectric micro-machined ultrasonic transducers (PMUTs) to be used with a Doppler color flow rotational IVUS imaging system. In one embodiment, a rotational intravascular ultrasound (IVUS) device includes: a flexible elongate body; a piezoelectric micromachined ultrasound transducer (PMUT) coupled to a distal portion of the flexible elongate body; and an application-specific integrated circuit (ASIC) coupled to the distal portion of the flexible elongate body. The ASIC is electrically coupled to the PMUT and includes a pulser, an amplifier, a protection circuit, and timing and control circuitry for coordinating operation of the pulser, amplifier, and protection circuit. The PMUT transducer is mounted with a tilt angle such that the IVUS catheter can be used to collect Doppler ultrasound blood flow data in conjunction with the IVUS imaging.