Catheter tip tracking for interventional procedures monitored by magnetic resonance imaging

An interventional instrument for use in an interventional procedure performed on an associated subject and monitored by magnetic resonance imaging, the interventional instrument including:

• an element adapted for insertion into the associated subject for performing the interventional procedure:
• an optical fiber arranged to deliver light to a selected location on the element;
• and
• a resonant circuit disposed at the selected position on the element, the resonant circuit including a coil having a coil inductance and a light-sensitive metal-insulator-semiconductor capacitor optically coupled with the optical fiber and having a selectable capacitance determined by an intensity of light delivered thereto by the optical fiber, a selected resonance frequency of the resonant circuit being determined by the coil inductance and the selected capacitance, the selected resonance frequency being selectable by adjusting the light intensity to correspond to a tuned resonance frequency detected by the magnetic resonance imaging, the light-sensitive metal-insulator-semiconductor capacitor including:
• a heavily doped semiconductor substrate,
• a more lightly doped semiconductor layer disposed over the heavily doped semiconductor substrate,
• an insulator layer disposed over the more lightly doped semiconductor layer, and
• a conductive layer disposed over the insulator layer.

A method of using an interventional instrument which includes an element adapted for insertion into the associated subject for performing the interventional procedure;

• an optical fiber arranged to deliver light to a selected location on the element;
• and a resonant circuit disposed at the selected position on the element, the resonant circuit including a coil having a coil inductance and a light-sensitive metal-insulator-semiconductor capacitor optically coupled with the optical fiber and having a selectable capacitance determined by an intensity of light delivered thereto by the optical fiber, a selected resonance frequency of the resonant circuit being determined by the coil inductance and the selected capacitance, the selected resonance frequency being selectable by adjusting the light intensity to correspond to a tuned resonance frequency detected by the magnetic resonance imaging, the method including:
• exciting magnetic resonance in a volume containing the selected location on the element;
• acquiring k-space data;
• for the acquiring of k-space data, intensity-modulating the intensity of light delivered to the light-sensitive metal-insulator-semiconductor capacitor to modulate the selected resonance frequency between the tuned resonance frequency and a detuned resonance frequency not detected by the magnetic resonance imaging;
• Fourier transforming k-space data acquired with the selected resonance frequency tuned to the tuned resonance frequency into a first spatial data set;
• Fourier transforming k-space data acquired with the selected resonance frequency detuned into a second spatial data set;
• and
• subtractively combining the first and second spatial data sets to produce a subtractively combined data set.

An intravascular imaging method performed using an interventional instrument which includes an element adapted for insertion into the associated subject for performing the interventional procedure;

• an optical fiber arranged to deliver light to a selected location on the element;
• and a resonant circuit disposed at the selected position on the element, the resonant circuit including a coil having a coil inductance and a light-sensitive metal-insulator-semiconductor capacitor optically coupled with the optical fiber and having a selectable capacitance determined by an intensity of light delivered thereto by the optical fiber, a selected resonance frequency of the resonant circuit being determined by the coil inductance and the selected capacitance, the selected resonance frequency being selectable by adjusting the light intensity to correspond to a tuned resonance frequency detected by the magnetic resonance imaging, the intravascular imaging method including:
• inserting at least a portion of the element including the selected location into the associated subject;
• acquiring magnetic resonance tracking data with the element inserted into the associated subject and with the intensity of light delivered to the light-sensitive metal-insulator-semiconductor capacitor selecting the tuned resonance frequency;
• determining position coordinates of the selected location on the element in the associated subject based on the magnetic resonance tracking data;
• acquiring intravascular magnetic resonance imaging data of a region including the determined position coordinates with the element inserted into the associated subject and with the intensity of light delivered to the light-sensitive metal-insulator-semiconductor capacitor selecting a detuned resonance frequency not detected by the magnetic resonance imaging;
• and
• reconstructing the intravascular magnetic resonance imaging data to form a reconstructed image.