MRI guidewire
Inventors
Assignees
US Department of Health and Human Services
Publication Number
US-9259556-B2
Publication Date
2016-02-16
Expiration Date
2028-12-31
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Abstract
A guidewire (100) for use with interventional magnetic resonance imaging has a guidewire body (102) having a distal end and a proximal end and reserving a space therein, a dipole antenna (108) disposed in the space reserved within the guidewire body, the dipole antenna being adapted to be electrically connected to a signal processing system through a first signal channel (110) through the proximal end of the guidewire body, and a loop antenna (112) disposed in the space reserved within the guidewire body toward the distal end of the guidewire body, the loop antenna (112) being adapted to be electrically connected to the signal processing system through a second signal channel (114) through the proximal end of the guidewire body. The dipole antenna and the loop antenna are each constructed to receive magnetic resonance imaging signals independently of each other and to transmit received signals through the first and second signal channels, respectively, to be received by the signal processing system. An interventional magnetic resonance imaging system includes an active guidewire.
Core Innovation
The invention relates to a guidewire for use with interventional magnetic resonance imaging (iMRI) that includes a guidewire body reserving space within which are disposed two types of antennas: a dipole antenna and a loop antenna. The dipole antenna is connected via a first signal channel through the proximal end of the guidewire body, and the loop antenna is connected via a second signal channel through the same proximal end. Each antenna independently receives MRI signals and transmits these to a signal processing system.
The issue addressed by the invention stems from limitations in existing MRI-compatible guidewire visualization methods. Passive visualization methods based on susceptibility artifacts provide either the tip or shaft visualization but not both simultaneously, which is insufficient for safe and effective guidewire advancement in tortuous vessels. Active visualization methods using coils integrated into the device provide robust signals but still do not satisfactorily visualize both distal tip and shaft concurrently.
The invention solves this problem by embedding both a dipole antenna and a loop antenna within the guidewire body, enabling simultaneous and independent reception of MR signals for extended shaft visualization via the dipole antenna and precise tip visualization via the loop antenna microcoil. This configuration supports enhanced real-time guidance during vascular interventions by MR imaging, improving position localization along the guidewire length as well as at the distal tip.
Claims Coverage
The patent includes two independent claims focused on active guidewires equipped with dual antennas for interventional magnetic resonance imaging. The inventive features center on the construction and arrangement of guidewire bodies with integrated dipole and loop antennas that independently receive MRI signals for shaft and tip visualization respectively.
Guidewire with integrated dipole and loop antennas
A guidewire body is constructed with reserved internal space accommodating a dipole antenna and a loop antenna. The dipole antenna is electrically connected via a first signal channel and the loop antenna via a second signal channel through the proximal end of the guidewire. The loop antenna includes a microcoil positioned adjacent the distal tip for precise tip visualization, while the dipole antenna is positioned along the shaft to provide visualization information of the elongated shaft. The antennas receive and transmit MRI signals independently.
Construction of dipole antenna with nested hypotube structure
The dipole antenna comprises an outer hypotube and an inner hypotube disposed within a lumen defined by the outer hypotube, with an electrical insulation layer between them. The inner hypotube extends beyond the distal end of the outer hypotube forming a whip portion tuned to the Larmour frequency for MRI operation. The hypotubes are made from MRI-compatible materials such as Nitinol, and the whip portion may have a gold surface coating. The hypotube assembly forms at least part of the first signal channel.
Electrical connection of loop antenna via micro coaxial cable or twisted pair
The loop antenna microcoil is electrically connected to the second signal channel through a micro coaxial electrical cable disposed within the guidewire body or alternatively through a twisted pair of electrical wires. These conductors extend internally along the guidewire and enable independent signal transmission corresponding to the tip visualization.
Overall, the claims cover an active guidewire designed for interventional MRI with a coaxial arrangement of a dipole antenna dedicated to shaft visualization and a loop antenna microcoil dedicated to tip localization. The design incorporates specific MRI-compatible constructions and electrical interconnections enabling independent signal reception over separate channels for enhanced imaging guidance.
Stated Advantages
Simultaneous and independent visualization of both the guidewire shaft and precise distal tip location.
Improved safety and steering accuracy during vascular interventions due to enhanced real-time signal reception along the entire guidewire length.
Use of MRI-compatible materials such as Nitinol with suitable coatings maintains mechanical properties while enabling efficient antenna function.
Improved signal-to-noise ratio and spatial sensitivity by combining the longitudinal sensitivity of the dipole antenna and localized tip sensitivity of the loop microcoil.
Documented Applications
Use in interventional magnetic resonance imaging procedures for vascular interventions where precise visualization of guidewire position and orientation is essential.
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