Method of localizing an object in an MR apparatus, a catheter and an MR apparatus for carrying out the method
First Claim
1. A method of localizing a medical instrument in a body in an examination zone of a magnetic resonance apparatus, the method comprising the steps of:
- evaluating the interaction between an electromagnetic resonant circuit disposed on the medical instrument and an RF field which is applied for nuclear magnetization in the body in the examination zone; and
tuning the resonant circuit to the frequency of the RF field, the resonant circuit being capable of assuming two states with a different resonant circuit quality factor;
inducing a first state of nuclear magnetization with a flip angle by means of a first RF pulse while the resonant circuit is in one of the two states; and
rephasing the nuclear magnetization by means of a second RF pulse while the resonant circuit is in the other one of the two states.
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Accused Products
Abstract
A method for localizing an object, preferably a medical instrument and notably a catheter (60) introduced into a body in the examination volume of an apparatus operating on the basis of magnetic resonance (MR), evaluates the interaction between an electromagnetic resonant circuit (6), mounted on the object (60), and an RF field applied in the MR apparatus for nuclear magnetization of the body. In such a method a simple, fast and accurate localization of an object, notably a catheter, in an image-forming MR device is enabled in that use is made of a resonant circuit (6) which is tuned to the frequency of the RF field and is capable of assuming two states with a different resonant circuit quality factor, in that in a first state nuclear magnetization with a flip angle is produced by means of a first RF pulse while the resonant circuit (6) is in one of the two states, and that in a second state a second RF pulse is applied so as to rephase the nuclear magnetization while the resonant circuit (6) is in the other one of the two states.
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Citations
17 Claims
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1. A method of localizing a medical instrument in a body in an examination zone of a magnetic resonance apparatus, the method comprising the steps of:
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evaluating the interaction between an electromagnetic resonant circuit disposed on the medical instrument and an RF field which is applied for nuclear magnetization in the body in the examination zone; and
tuning the resonant circuit to the frequency of the RF field, the resonant circuit being capable of assuming two states with a different resonant circuit quality factor;
inducing a first state of nuclear magnetization with a flip angle by means of a first RF pulse while the resonant circuit is in one of the two states; and
rephasing the nuclear magnetization by means of a second RF pulse while the resonant circuit is in the other one of the two states. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A catheter for use with a magnetic resonance imaging apparatus, the catheter comprising:
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a resonant circuit having an inductance in the form of a microcoil;
a capacitance connected parallel to the inductance; and
a switching element provided in the resonant circuit, the switching element for influencing the resonant circuit quality factor of the resonant circuit. - View Dependent Claims (9, 10)
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11. A magnetic resonance apparatus comprising:
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a main magnet for generating a substantially uniform, steady magnetic field in an examination region;
a gradient coil system for generating gradient fields in the examination region;
an RF transmit coil for transmitting at least first and second RF signals into the examination region and exciting spin resonance in an object disposed within the examination region;
an RF receive coil for receiving RF signals, induced by the RF transmit coil, from the examination region; and
a medical device, the medical device comprising;
a resonant circuit disposed on the medical device, the resonance circuit including an inductance, a capacitance connected in parallel with the inductance, and a non-linear element in electrical connection with the inductance and capacitance. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification