Apparatus for doppler interferometric imaging and imaging guidewire
First Claim
1. An interferometer for performing real time intravascular imaging, comprising:
- a low coherence light source;
means for splitting the light source into a sampling beam and reference beam;
a reference optical path for receiving the reference beam, wherein the reference optical path leads to a means for causing ramp-wise modulation of a length of the reference optical path length;
a sampling optical path for receiving the sampling beam, the sampling optical path leading to a vascular sample and terminating at an inner wall of a vessel;
means for ramp-wise modulation of a length of the reference optical path length comprising a spiral optical element with a spiral receiving surface, a rotational shaft, the spiral receiving surface mounted on the rotational shaft, the shaft having an axis positioned substantially parallel with axis of the reference beam as the reference beam approaches the spiral receiving surface, and means for causing the shaft to rotate;
means for combining reflections from the reference optical path and sampling optical path;
a polarization means for decomposition of each of said optical outputs into two optical signals with orthogonal polarizations;
photodetection means for generating electrical signals from the resulting combined optical signals;
electronic substation means for subtracting two electrical signals corresponding to the same polarizations for reducing excessive noise of the light source;
envelope detecting means for forming an envelope of an amplitude of the electrical signals from the photodetection means; and
means for processing said electrical signals to form a cross-sectional image of the vessel.
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Accused Products
Abstract
An apparatus for Doppler interferometric imaging comprising a balanced fiber optic interferometer, a low coherence light source and an imaging guidewire is used for diagnosis of intravascular obstructions. The imaging guidewire, which is also used for placement of over-the-wire catheters, comprises a hollow elongated body, an optical fiber, a rotatable mirror at its distal end and a micromotor operable to sweep the sampling beam around the vessel. An optical length modulator in the reference arm of the interferometer provides ramp wise modulation of optical length and a Doppler frequency shift for the reference beam. The polarization diversity detection scheme and two envelope detectors tuned for the Doppler frequency, perform measurements of the intensities of the two linear polarizations of the retroreflected light. Combined with current values of the optical length of the reference arm and angular position of the sweeping mirror, this information is used for reconstruction of the cross-sectional images of the vessel in two polarizations. These images are used for measurements of the geometry and recognition of the morphology of an intravascular obstruction which is utilized for diagnosis of atherosclerosis and real-time guidance of interventional procedures like PTCA.
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Citations
12 Claims
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1. An interferometer for performing real time intravascular imaging, comprising:
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a low coherence light source; means for splitting the light source into a sampling beam and reference beam; a reference optical path for receiving the reference beam, wherein the reference optical path leads to a means for causing ramp-wise modulation of a length of the reference optical path length; a sampling optical path for receiving the sampling beam, the sampling optical path leading to a vascular sample and terminating at an inner wall of a vessel; means for ramp-wise modulation of a length of the reference optical path length comprising a spiral optical element with a spiral receiving surface, a rotational shaft, the spiral receiving surface mounted on the rotational shaft, the shaft having an axis positioned substantially parallel with axis of the reference beam as the reference beam approaches the spiral receiving surface, and means for causing the shaft to rotate; means for combining reflections from the reference optical path and sampling optical path; a polarization means for decomposition of each of said optical outputs into two optical signals with orthogonal polarizations; photodetection means for generating electrical signals from the resulting combined optical signals; electronic substation means for subtracting two electrical signals corresponding to the same polarizations for reducing excessive noise of the light source; envelope detecting means for forming an envelope of an amplitude of the electrical signals from the photodetection means; and means for processing said electrical signals to form a cross-sectional image of the vessel. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A device for real time intravascular imaging, comprising:
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an imaging guidewire having an elongated hollow body with a distal and proximal end and a throughbore extending therethrough, an optical fiber positioned in the throughbore;
a micro optical collimator positioned at distal end of the fiber;
a housing proximate the distal end of the guidewire proximate said collimator;
a mirror positioned in the housing and capable of rotating about a central axis of the throughbore;
micromotor means for rotating the mirror; and
connection means for providing electrical connection of the micromotor means to a power source;a fiber optic interferometer comprising; a low coherence light source; a beam splitting means for splitting light into a reference and a sampling beam; a reference arm for receiving the reference beam; means for causing ramp-wise modulation of a length of the reference arm comprising a spiral optical element with a spiral receiving surface, a rotational shaft, the spiral receiving surface mounted on the rotational shaft, the shaft having an axis positioned substantially parallel with an axis of the reference beam as the reference beam approaches the spiral receiving surface, and means for causing the shaft to rotate; a sampling arm extending through the guidewire, terminating at a vessel wall;
means for combining optical signals from the reference arm and the sampling arm and for generating two optical outputs;a polarization means for decomposition of each of said optical outputs into two optical signals with orthogonal polarizations; photodetection means for converting the optical signals to electrical RF signals;
electronic subtraction means for subtracting two electrical signals corresponding to the same polarizations for reducing excessive noise of the light source;envelope detection means for restoration of the amplitude envelope of the RF signals; means for converting the outputs from the envelope detection means into digital signals; computer means for receiving the digital signals and processing the information to reconstruct cross-sectional images of a vessel; and display means for displaying cross-sectional images of the vessel.
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8. An imaging guidewire, comprising:
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an elongated hollow body with a distal end, a proximal end and a throughbore extending longitudinally therethrough; an optical fiber extending through the throughbore; a micro optical collimator positioned at a distal end of the optical fiber; an optical connector means for connecting the proximal end to a low coherence interferometer; a hermetic housing mounted proximate said distal end of the hollow body proximate the collimator; a mirror mounted within said housing for reflecting light emanating from said collimator in a generally transverse direction and to the vessel walls, said mirror mounted for rotation about an axis substantially in line with a central throughbore axis; a micromotor means positioned proximate the distal end for rotating the mirror; and connection means for providing electrical connection of the micromotor means to a power source. - View Dependent Claims (9, 10, 11, 12)
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Specification