MRI compatible 3-D intracardiac echography catheter and system
Inventors
Degertekin, Fahrettin Levent • Tekes, Coskun • Lederman, Robert Jay • Kocaturk, Ozgur • Rashid, M. Wasequr • Ghovanloo, Maysam
Assignees
Georgia Tech Research Corp • US Department of Health and Human Services
Publication Number
US-11039811-B2
Publication Date
2021-06-22
Expiration Date
2034-09-25
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Abstract
An intracardiac imaging system has an MRI compatible intracardiac echography catheter having transmitters, receivers, a multiplexer, and a beamformer. The catheter can include an atraumatic tip disposed on the distal end of the catheter, a pair of inductively coupled coils proximal the atraumatic tip, at least one CMUT-on-CMOS volumetric imaging chip disposed between the pair of coils, and a cable lumen disposed within the volume sized to house a small number of electrical connections due to significant multiplexing in the CMUT-on-CMOS chip. The catheter can be made of MRI compatible materials and can include active cooling channels.
Core Innovation
The invention relates to an MRI compatible 3D intracardiac echography catheter and system employing capacitive micromachined ultrasonic transducer (CMUT)-on-CMOS technology for volumetric ultrasound imaging. The intracardiac imaging system includes transmitters, receivers, a multiplexer, and a beamformer integrated on a CMUT-on-CMOS chip. The catheter comprises an atraumatic tip, inductively coupled coils for MRI visibility, and cable lumens sized for minimal electrical connections through significant multiplexing. The design allows use within MRI as well as X-ray systems to guide intracardiac interventions in real time.
The problem being addressed arises from limitations of existing intracardiac echography catheters and imaging techniques used during cardiac interventions. Conventional 2D and limited 3D intracardiac ultrasound catheters do not provide full-volume en face real-time images to depict complex cardiac structures and catheter navigation accurately. They require adjunctive X-ray fluoroscopy and struggle with poor spatial resolution and constraints such as interposed bone, lung tissue, and limited probe access. Existing 3D TEE and ICE probes are either too large for pediatric use or lack sufficient volume coverage and imaging speed while requiring numerous electrical connections incompatible with MRI, leading to procedural inefficiencies, increased radiation exposure, and limited procedural success.
The invention solves these problems by providing an intracardiac catheter that integrates a full 3D ultrasound imaging system on a CMUT-on-CMOS chip with massive on-chip multiplexing of receive signals to reduce the number of cables by a ratio of 15-to-1 to 50-to-1. This reduction minimizes RF-induced heating under MRI and allows catheter miniaturization and active cooling. The catheter includes on-chip beamforming, coded excitation, and multiplexing implemented via frequency division multiplexing, time division multiplexing, or orthogonal frequency division multiplexing. The system is designed for real-time volumetric intracardiac imaging with fewer than 10 transmit firings, with the catheter being steerable, MRI safe, and including MRI-visible inductively coupled markers for navigation. The design enables full-volume, high resolution, radiation-free, and real-time visualization of cardiac structures and catheters to improve interventional procedures' safety and success.
Claims Coverage
The patent contains two independent claims focused on the design and functional features of the ultrasound imaging catheter and an intracardiac echography catheter with specific structural and compatibility characteristics. Fourteen main inventive features are extracted from these claims.
Ultrasound imaging catheter compatible with MRI
The catheter comprises multiple transmitters and receivers, a multiplexer that simultaneously receives multiple receiver signals and reduces the number of output signals to fewer than the received signals, and a beamformer communicating with transmitters, ensuring MRI compatibility.
Multiplexing ratio for output signal reduction
The multiplexer reduces receiver signals by a ratio between 15-to-1 and 50-to-1, including producing output signals using time division multiplexing (TDM).
Inductively or conductively coupled MRI-visible markers
The catheter includes inductively or conductively coupled markers for catheter tracking during MRI and is visible with both MRI and X-ray imaging.
MRI compatible housing and cabling
The catheter includes a housing containing the transmitters, receivers, multiplexer, and beamformer, all compatible with MRI, along with output signal cables within the housing that are MRI compatible.
CMUT-on-CMOS integrated electronics
The catheter integrates transmitters, receivers, multiplexing, and beamforming on at least one CMUT-on-CMOS chip, featuring CMUT transmit and receive elements positioned proximally, allowing simultaneous beamforming and multiplexing.
High multiplexing of receiver signals on CMUT devices
The multiplexer handles receiving at least half of the CMUT received signals simultaneously with output reduction ratios ranging from 15-to-1 up to 50-to-1, with beamforming communicating simultaneously with the CMUT transmitters.
Stacked CMUT-on-CMOS chip configuration
A first CMUT-on-CMOS chip contains partial transmitters and optionally receivers, while a second chip contains the remainder, oriented in a stacked configuration for integration.
Intracardiac catheter structural features
The catheter has an atraumatic distal tip, MRI visible inductively or conductively coupled marker coils proximal and distal to the tip, a cable lumen, and is sized approximately 6 to 10 French, with MRI compatible materials and optional cooling lumens.
Multiplexer producing output signals with TDM
The multiplexer produces output signals using time division multiplexing to reduce the number of output cables and enable MRI compatibility and catheter miniaturization.
Overall, the claims cover an MRI compatible 3D intracardiac ultrasound imaging catheter integrating CMUT-on-CMOS technology with on-chip multiplexing and beamforming, inductively coupled MRI-visible markers, minimal output cables via multiplexing ratios of 15-to-1 to 50-to-1, and catheter structural features enabling safe and efficient real-time volumetric imaging compatible with MRI and X-ray guidance.
Stated Advantages
Radiation-free catheter navigation and imaging, especially beneficial for pediatric use.
Reduced procedural complexity, duration, and complications through enhanced real-time volumetric visualization of cardiac anatomy and catheter devices.
Significant reduction in electrical cables (up to 50-fold), decreasing RF-induced heating and enabling catheter miniaturization and active cooling.
MRI compatibility allowing combined real-time MRI and ultrasound guidance for complex intracardiac interventions.
Enables new procedures otherwise requiring surgery, such as non-surgical mitral repairs and simplified closures of septal defects and leaks.
Reduced need for general anesthesia by providing intracardiac imaging alternatives to transesophageal approaches.
Documented Applications
Real-time guidance of intracardiac catheter-based cardiovascular procedures such as atrial septal defect closure, ventricular septal defect closure, mitral valve repair, paravalvular leak repair, and left atrial appendage closure.
MRI safe catheter navigation and imaging to replace or complement X-ray fluoroscopy during structural heart interventions in adults and children.
Use in surgical alternatives like non-surgical extra-anatomic shunts and mitral valve leaflet procedures.
Real-time volumetric intracardiac echography during MRI to enable radiation-free catheter guidance and assessment of procedural success and complications.
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