US 2013/0172729 A1 · ACTIVE ADAPTIVE DETUNING SYSTEMS AND METHODS FOR INTERVENTIONAL DEVICES

Abstract

Active MRI compatible interventional devices, such as catheters, include at least one RF antenna so that they are visible under MRI analysis. However, metallic structures within intravascular devices may heat up significantly during interventional MRI procedures due to eddy current formation over the conductive transmission lines. The electrical field coupling that occurs between interventional devices and RF signals depend on the position and orientation of interventional device within the bore and the insertion length of the interventional device. The system detects an induced current signal during RF transmission phase and selectively adjusts the impedance value associated with the interventional device by using a varactor and integrated circuit components in such a manner that the currents induced in the interventional device are below a threshold current level, thereby controlling current levels and heating in the interventional device.

Claims20

Dependent claims

A system for use during a magnetic resonance imaging procedure, the system comprising:

a magnetic resonance imaging device to selectively:
apply a radio frequency radiation signal across a selected portion of a subject;
and
discontinue application of the radio frequency radiation signal across the selected portion of the subject;
an interventional device for insertion into the subject and proximate to the selected portion of the subject, the interventional device comprising:
a radio frequency antenna at a distal end of the interventional device to receive an induced current based on another radio frequency signal emitted from tissue surrounding the radio frequency antenna when the interventional device is inserted in the subject;
and
an inner conductor along a length of the interventional device and connected to the radio frequency antenna to conduct the induced current;
an adaptive detuning circuit connected to the inner conductor to:
iteratively adjust an impedance value of the interventional device through each of a plurality of impedance values;
determine a corresponding magnitude of the induced current in the inner conductor for each of the plurality of impedance values;
and
set the impedance value of the interventional device to a first one of the plurality of impedance values where the corresponding magnitude of the induced current is below a threshold current level.

10 more elements

An adaptive detuning circuit for use in a magnetic resonance system during insertion of an interventional device into a subject during a magnetic resonance imaging procedure, wherein the magnetic resonance imaging system selectively applies and discontinues application of a radio frequency radiation signal across a selected portion of a subject, and wherein the interventional device comprises a radio frequency antenna to receive an induced current based on another radio frequency signal emitted from tissue proximate to the radio frequency antenna and an inner conductor connected to the radio frequency antenna to conduct the induced current conductor, the adaptive detuning circuit comprising:

a connector to connect to the inner conductor;
and
a control circuit to:
iteratively adjust an impedance value of the interventional device through each of a plurality of impedance values;
determine a corresponding magnitude of the induced current in the inner conductor for each of the plurality of impedance values;
and
set the impedance value of the interventional device to a first one of the plurality of impedance values where the corresponding magnitude of the induced current is below a threshold current level.

4 more elements

A method for adjusting an impedance value associated with an interventional device during insertion of the interventional device into a subject during a magnetic resonance imaging procedure, the method comprising:

inserting an interventional device having an inner conductor and a radio frequency antenna into the subject;
applying a radio frequency radiation signal across a selected portion of a subject via a magnetic resonance imaging device;
discontinuing application of the radio frequency radiation signal across the selected portion of the subject;
receiving an induced current in the conductor via the radio frequency antenna based on another radio frequency signal emitted from tissue surrounding the radio frequency antenna when application of the radio frequency radiation signal is discontinued;
iteratively adjusting an impedance value of the interventional device through a plurality of impedance values;
determining a corresponding magnitude of the induced current in the inner conductor for each of the plurality of impedance values;
and
setting the impedance value of the interventional device to a first one of the plurality of impedance values where the corresponding magnitude of the induced current is below a threshold current level.

5 more elements

Dependencies are inferred from the claim text.

Active adaptive detuning systems and methods for interventional devices

Life of this patent

Active adaptive detuning systems and methods for interventional devices

Life of this patent

Abstract

Claims20