Optical coherence tomography for biological imaging

Information

  • Patent Grant
  • 11839493
  • Patent Number
    11,839,493
  • Date Filed
    Tuesday, February 22, 2022
    2 years ago
  • Date Issued
    Tuesday, December 12, 2023
    a year ago
Abstract
Described herein are catheters for use with Optical Coherence Tomography (OCT) that include an optical fiber core having a first refractive index and an interface medium having a second refractive index, where the first and second refractive indexes are mismatched such that receiving electronics configured to receive optical radiation reflected from the reference interface and the target operate in a total noise range that is within 5 dB of the shot noise limit. These OCT catheters may include a silicon die mirror having a reflective coating that is embedded in the interface medium. The optical fiber can be fixed at just the distal end of the catheter, and may be managed within a handle that is attached to the proximal end of the catheter body, and is configured to allow rotation of the both catheter body and the optical fiber relative to the handle.
Description
INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.


FIELD OF THE INVENTION

Described herein are imaging devices and systems for use in biological probes. In particular, described herein are catheter-based imaging systems using Optical Coherence Tomography (OCT).


BACKGROUND OF THE INVENTION

In cardiovascular surgery, as well as other medical applications, there is frequently a need to extend very thin (few millimeter diameter), long (30-150+ cm) and sterile catheters into thin-walled (e.g., 1-1.5 millimeter wall thickness) biological lumens, including blood vessels such as arteries and veins.


A number of vascular diseases, such as coronary artery disease and peripheral vascular disease, are caused by the build-up of atherosclerotic deposits (plaque) in the arteries, which limit blood flow to the tissues that are supplied by that particular artery. Disorders caused by occluded body vessels, including coronary artery disease (CAD) and peripheral artery disease (PAD) may be debilitating and life-threatening. Chronic Total Occlusion (CTO) can result in limb gangrene, requiring amputation, and may lead to other complications and eventually death. Increasingly, treatment of such blockages may include interventional procedures in which a guidewire is inserted into the diseased artery and threaded to the blocked region. There the blockage may be either expanded into a more open position, for example, by pressure from an inflated catheter balloon (e.g., balloon angioplasty), and/or the blocked region may be held open by a stent. Treatment of such blockages can also include using a catheter to surgically remove the plaque from the inside of the artery (e.g., an atherectomy).


When the artery is totally blocked by plaque, it is extremely difficult, and potentially dangerous to force the guidewire through the occlusion. An obstruction or plaque may be composed of relatively tough fibrous material, often including hard calcium deposits. Forcing a guidewire or catheter past such obstructions may cause the guidewire to puncture the walls of the vessel (e.g., artery) or cause it to enter the layers forming the artery, further damaging the tissue. Thus, there remains a need for guidewire positioning devices that can effectively traverse occluded vessels, and particularly chronically occluded vessels. Such devices would enable positioning of a guidewire and therefore enable positioning of stents and other devices, leading to improved patient outcomes and a reduction in patient morbidity and mortality.


Moreover, there is medical interest in equipping catheter-based cardiovascular catheters with sensors that can help direct atherectomy and other surgical procedures. For example, it would be useful to have sensors that can give the surgeon immediate visual feedback as to whether a particular tissue is diseased and/or how far away the cutting portion of a catheter is from the boundary of a particular blood vessel layer to minimize the risk of accidental damage. Conventional radiological imaging methods and ultrasound imaging systems have been attempted for such surgical procedures. However, neither ultrasound nor radiological imaging methods have enough resolution to help guide the operation of the catheter over the critical last fraction of a millimeter between the interior of a blood vessel and the exterior of the blood vessel. Moreover, standard radiological techniques cannot easily discriminate between healthy tissue and diseased tissue unless the tissue has become heavily calcified. Further, the components of an ultrasound system are generally too large to implement in small dimensions.


Optical Coherence Tomography (OCT) has been proposed as one technique that may be particularly helpful for imaging regions of tissue, including within a body lumen such as a blood vessel. At a basic level, OCT relies on the fact that light traveling from a source and scattering from more distant objects takes longer to travel back than light scattering from nearby objects. Due to the wave nature of light, very small timing differences caused by light signals traveling different distances on the micron scale can cause constructive or destructive interference with reference light signals. OCT systems measure the resulting interference to obtain an image of the target. Unfortunately, however it has thus far proven difficult to provide stable and reliable OCT systems for use in a catheter. A typical OCT system requires one or more interferometers to distinguish the signal from the applied light. In addition, most known OCT systems, when applied to catheters, include a fiber that is rotated (often at high rates) within the catheter in order to scan around a lumen. These systems typically require relatively high power operation, since the many components necessary for rotating and managing the OCT pathway (e.g., fiber) result in optical losses.


Thus, there is a need for efficient and robust OCT systems that are compatible with catheter applications and uses. Described herein are enhanced Optical Coherence Tomography (OCT) systems that that overcome many of the problems described above.


Referring to FIG. 1, a typical OCT device includes a target arm and a reference arm to generate a reference signal. In order to provide the interference reference signal, the OCT device will split an illuminating light signal from the source in two equal or unequal parts, send part of the illuminating light to the target of interest through one target optical “target arm” and send the other part of the illuminating light down a separate reference arm. Light from the separate reference arm reflects off of a mirror, and then returns and interferes with the scattered light that is returning from the target optical arm after bouncing off of the target. In a traditional OCT device, the reference arm length is engineered to be exactly the same length as the target arm so that the interference effect is maximized. The resulting interference between the two beams creates interference effects known as fringes that can be used to measure the relative reflectivity of various layers of the target. Using this information, an image of the object can be generated.


By contrast to the more established applications for OCT, cardiovascular catheters, which are intended for one-time use in blood vessel environments, must be of the highest level of sterility. To obtain such sterility, cardiovascular catheters are typically produced as low-cost disposable items that can be factory sterilized. During a medical procedure, such a catheter is typically removed from the factory sterile container. The proximal end of the catheter is connected to equipment needed to control the catheter (which in this case would also include the link to the OCT engine used to drive any OCT optical fiber in the catheter), and the distal tip is immediately inserted into the patient's body. The catheter is then discarded once the procedure is complete.


Producing low-cost disposable catheters can be difficult as a result of the need for precise reference arm matching and expensive optics. Thus, there is also a need for a low-cost OCT catheter.


SUMMARY OF THE INVENTION

Described herein are OCT catheter, catheter systems, and methods of using and manufacturing them. In general, the OCT catheters and systems described herein are appropriate for use in a patient in order to visualize the internal structures within a lumen of the body in real time. These systems may allow control and navigation of the catheter, including navigation around and through complex anatomy such as bifurcations, ostials, regions of tortuosity, and the like. Further, the real-time and efficient imaging, as well as the control of the imaging system may allow a reduction in procedure time and improvements for long- and short-term outcomes.


In general, a system for optical coherence tomography may include a source of optical radiation, an optical fiber, receiving electronics, an interface medium, and a processor. Typically, the optical fiber has a core providing a common path for optical radiation reflected from a reference interface and a target. The core has a first refractive index. As described herein, the receiving electronics are configured to receive the optical radiation reflected from the reference interface and the target. The interface medium is at the reference interface and in optical contact with the optical fiber. The interface medium has a second refractive index. The first refractive index and the second refractive index are mismatched such that the receiving electronics operate in a total noise range that is within 5 dB of the shot noise limit. The processor generates an image of the target based upon the optical radiation received by the receiving electronics.


This and other embodiments may include one or more of the following features. The first refractive index and the second refractive index can be mismatched such that the receiving electronics operate in a total noise range that is within 3 dB of the shot noise limit. The first refractive index and the second refractive index can be mismatched such that the receiving electronics operate in a total noise range that is within 2 dB of the shot noise limit. The source of optical radiation can be a swept-frequency source.


The system can further include a mirror in the interface medium, and the mirror can be configured to reflect the optical radiation from the optical fiber to the target. The mirror can include a gold-coated silicon die. The interface medium can be a solid transparent medium. The interface medium can be in optical contact with a distal end of the core.


The system can further include a directional element configured to relay the optical radiation from the source to a distal end of the core.


The first refractive index n1 and the second refractive index n2 can be mismatched such that:








P
out


P
in


=

(



n
1

-

n
2




n
1

+

n
2



)





wherein Pin is the power of the optical radiation at the distal end of the optical fiber prior to entering the interface medium, and wherein Pout is the power of the optical radiation reflected from the reference interface such that the receiving electronics operate in a total noise range that is within 5 dB of the shot noise limit. In general, a catheter for use with optical coherence tomography includes an elongate catheter body, an optical fiber in the elongate catheter body, and an interface medium. The optical fiber has a core providing a common path for optical radiation reflected from a reference interface and a target. The core has a first refractive index. The interface medium is in optical contact with the optical fiber. The interface medium has a second refractive index. The first refractive index and the second refractive index are mismatched such that receiving electronics configured to receive optical radiation reflected from the reference interface and the target operate in a total noise range that is within 5 dB of the shot noise limit.


This and other embodiments may include one or more of the following features. The first refractive index and the second refractive index can be mismatched such that the receiving electronics operate in a total noise range that is within 3 dB of the shot noise limit. The first refractive index and the second refractive index can be mismatched such that the receiving electronics operate in a total noise range that is within 2 dB of the shot noise limit.


The system can further include a mirror in the interface medium. The mirror can be configured to reflect the optical radiation from the optical fiber to the target. The mirror can include a gold-coated silicon die. The interface medium can be a solid transparent medium. The interface medium can be in optical contact with a distal end of the core.


The first refractive index n1 and the second refractive index n2 can be mismatched such that:








P
out


P
in


=

(



n
1

-

n
2




n
1

+

n
2



)





wherein Pin is the power of the optical radiation at the distal end of the optical fiber prior to entering the interface medium, and wherein Pout is the power of the optical radiation reflected from the reference interface such that the receiving electronics operate in a total noise range that is within 5 dB of the shot noise limit.


In general, a method of performing optical coherence tomography includes: transmitting optical radiation from a source through an optical fiber having a core, the core having a first refractive index; transmitting the optical radiation from the optical fiber through an interface medium, wherein the interface medium is in optical contact with the optical fiber, the interface medium having a second refractive index; transmitting optical radiation reflected from the target and reflected from a reference interface along a common path in the optical fiber to a detector; receiving the reflected optical radiation at receiving electronics, wherein the first refractive index and the second refractive index are mismatched such that the receiving electronics operate in a total noise range that is within 5 dB of the shot noise limit; and generating an image of the target based upon the reflected optical radiation received by the receiving electronics.


This and other embodiments may include one or more of the following features. The first refractive index and the second refractive index can be mismatched such that the receiving electronics operate in a total noise range that is within 3 dB of the shot noise limit. The first refractive index and the second refractive index can be mismatched such that the receiving electronics operate in a total noise range that is within 2 dB of the shot noise limit.


Transmitting optical radiation can include transmitting optical radiation comprises transmitting swept-source radiation. Transmitting optical radiation from the optical fiber through the interface medium further can include transmitting the optical radiation from the optical fiber to a mirror in the interface medium.


In general, a system for optical coherence tomography includes a source of optical radiation, an optical fiber providing a common path for optical radiation reflected from a reference and a target, a detector to receive the optical radiation reflected from the reference and the target, an interface medium at the reference interface and in optical contact with the distal end of the optical fiber, a mirror in the embedding medium, and a processor to generate an image of the target based upon the optical radiation received by the detector. The mirror includes a silicon die having a reflective coating.


This and other embodiments may include one or more of the following features. The reflective coating can be metallic. The metallic coating can be gold. The reflective coating may be at least








λ
min


2

π



Å





thick where λmin is the wavelength of light in the optical fiber. The metallic coating can be about 2,800 Å thick.


The system can further include an adhesion layer between the silicon die and the reflective coating. The adhesion layer can include nickel, titanium, or chromium. The adhesion layer can be between 50 Å and 200 Å thick. The adhesion layer can be about 100 Å thick. The interface medium can include an adhesive.


The mirror can be at least 95% reflective, such as at least 98% reflective. The interface medium can be a solid transparent medium. The source of optical radiation can be configured to provide swept-source radiation.


In general, a catheter for use with optical coherence tomography includes an elongate catheter body, an optical fiber in the elongate catheter body, an interface medium, and a mirror in the interface medium. The optical fiber provides a common path for optical radiation reflected from a reference interface and a target. The interface medium is at the reference interface and in optical contact with a distal end of the optical fiber. The mirror includes a silicon die having a reflective coating.


This and other embodiments may include one or more of the following features. The interface medium can include an adhesive. The reflective coating can be metallic. The metallic coating can be gold. The reflective coating can be at least








λ
min


2

π



Å





thick where λmin is the wavelength of light in the optical fiber. The reflective coating can be about 2,800 Å thick.


The catheter can further include an adhesion layer between the silicon die and the reflective coating. The adhesion layer can be nickel, titanium, or chromium. The adhesion layer can be between 50 Å and 200 Å thick. The adhesion layer can be about 100 Å thick. The mirror can be at least 95% reflective, such as at least 98% reflective.


In general, a method of performing optical coherence tomography includes transmitting optical radiation from a source through an optical fiber; transmitting the optical radiation from the optical fiber to a mirror embedded in an interface medium, wherein the mirror comprises a silicon die having a reflective coating, and wherein the interface medium is in optical contact with a distal end of a core of the optical fiber; reflecting the optical radiation from the mirror to a target; reflecting the optical radiation from a reference interface, the reference interface between the optical fiber and the interface medium; transmitting optical radiation reflected from the target and reflected from the reference interface along a common path in the optical fiber to a detector; receiving the reflected optical radiation at a detector; and generating an image of the target based upon the reflected optical radiation received by the detector.


This and other embodiments may include one or more of the following features. Transmitting optical radiation can include transmitting swept-source radiation. The reflective coating can be metallic. The metallic coating can be gold. The metallic coating may be at least








λ
min


2

π



Å





thick where λmin is the wavelength of light in the optical fiber. The metallic coating can be about 2,800 Å thick.


The method can further include an adhesion layer between the silicon die and the reflective coating. The adhesion layer can include nickel, titanium, or chromium. The adhesion layer can be between 50 Å and 200 Å thick. The adhesion layer can be about 100 Å thick. The mirror can be at least 95% reflective, such as at least 98% reflective.


In general, a system for optical coherence tomography includes a source of optical radiation, an elongate catheter body, an optical fiber, a handle attached to the proximal end of the elongate catheter body, a detector, and a processor. The optical fiber extends from a proximal end to a distal end of the elongate catheter body and can be attached to a distal end of the catheter body. The optical fiber provides a common path for optical radiation reflected from a reference and a target. The handle is configured to allow rotation of the catheter body and the optical fiber relative to the handle about a longitudinal axis of the elongate catheter body. The detector receives the optical radiation reflected from the reference and the target. The processor generates an image of the target based upon the optical radiation received by the detector.


This and other embodiments may include one or more of the following features. The optical fiber can be attached to the catheter body only near the distal end of the catheter body. A distal end of the optical fiber can be embedded in a solid transparent medium. The optical fiber can be not coaxial with the elongate catheter body. The handle can include a spooling mechanism, and the spooling mechanism can be configured to spool the optical fiber as it rotates. The handle can include a rotating mechanism, wherein one rotation of the rotating mechanism causes the catheter body and optical fiber to rotate about the longitudinal axis more than one time. One rotation of the rotating mechanism can cause the catheter body and optical fiber to rotate about the longitudinal axis at least two times. One rotation of the rotating mechanism can cause the catheter body and optical fiber to rotate about the longitudinal axis about four times.


In general, a catheter for use with optical coherence tomography includes an elongate catheter body, an optical fiber, and a handle. The optical fiber extends from a proximal end to a distal end of the elongate catheter body and is attached to the catheter body near a near a distal end of the catheter body. The optical fiber provides a common path for optical radiation reflected from a reference and a target. The handle is attached to the proximal end of the elongate catheter body and is configured to allow rotation of the catheter body and the optical fiber relative to the handle about a longitudinal axis of the elongate catheter body.


This and other embodiments may include one or more of the following features. The optical fiber can be attached to the catheter body only near the distal end of the catheter body. A distal end of the optical fiber can be embedded in a solid transparent medium. The optical fiber can be not coaxial with the elongate catheter body.


The handle can include a spooling mechanism, the spooling mechanism configured to spool the optical fiber as it rotates. The handle can include a rotating mechanism. One rotation of the rotating mechanism can cause the catheter body and optical fiber to rotate about the longitudinal axis more than one time. One rotation of the rotating mechanism can cause the catheter body and optical fiber to rotate about the longitudinal axis at least two times. One rotation of the rotating mechanism can cause the catheter body and optical fiber to rotate about the longitudinal axis about four times.


In general, a method of conducting optical coherence tomography includes: transmitting optical radiation from a source through an optical fiber, the optical fiber extending from a proximal end to a distal end of an elongate catheter body, the optical fiber attached to the catheter body near a distal end of the catheter body; transmitting the optical radiation from the optical fiber to a first position on a target; transmitting optical radiation reflected from the target and reflected from a reference along a common path in the optical fiber to a detector; receiving the reflected optical radiation at a detector; generating a first image of the first position of the target based upon the reflected optical radiation received by the detector; and manually rotating the catheter body and the optical fiber about a longitudinal axis of the catheter body such that a second image from a second position on the target can be obtained.


This and other embodiments may include one or more of the following features. Transmitting optical radiation can include transmitting swept-source radiation. Rotating the elongate catheter body and the optical fiber can include rotating a distal end of the catheter body and a distal end of the optical fiber together. Rotating the optical fiber can include spooling the optical fiber around a spooling mechanism of a handle attached to the proximal end of the catheter body. Rotating the elongate body and the optical fiber can include rotating a rotating mechanism of a handle attached to the proximal end of the catheter body such that the elongate body and the optical fiber rotate relative to the handle. Rotating the rotating mechanism once can cause the catheter body and optical fiber to rotate about the longitudinal axis more than one time. Rotating the rotating mechanism once can cause the catheter body and the optical fiber to rotate about the longitudinal axis at least two times. Rotating the mechanism once can cause the catheter body and the optical fiber to rotate about the longitudinal axis about four times.


The embodiments described herein may have one or more of the following advantages.


Using an OCT system with a common path optical fiber and an interface medium having indexes of refraction that are mismatched allows the OCT receiving electronics to operate in a total noise range that is within 5 dB of the shot noise limit. Operating within 5 dB of the shot noise limit advantageously ensures that noise in the receiving electronics is low. Keeping noise in the receiving electronics low results in a higher quality image. When used with an atherectomy catheter, for example, higher quality images advantageously allow for better identification of target tissue.


Using swept source optical radiation and a common path optical fiber as part of an OCT system allows for the use of a significantly simplified optical system compared to standard time-domain OCT embodiments or swept-source embodiments using Michaelson or Mach-Zehnder interferometers. This allows for the most efficient use of optical radiation, which in turn permits well optimized detection of signal and commensurately higher image quality.


Embedding a silicon die having a reflective coating in an interface medium provides a high reflectivity surface for reflection of light from the fiber to the tissue and back from the tissue into the fiber. The high reflectivity surface ensures that a high percentage of light from the source of optical radiation will be reflected and returned from the tissue. Having more light reflected from the target improves the interference fringe contrast, resulting in a higher quality image.


A system for OCT that includes a common path optical fiber attached to a distal end of the catheter body and a handle attached to the proximal end of the elongate catheter body to rotate the catheter and the optical fiber allows the optical fiber to rotate with the catheter body without breaking or stretching. Allowing the optical fiber to rotate with the catheter body ensures that images can be taken at 360° angles about the catheter body. Taking images at 360° angles around the catheter body ensures that more tissue can be imaged. Moreover, including an optical fiber attached to a distal end of the catheter body and a handle attached to the proximal end of the elongate body to rotate the catheter and the optical fiber advantageously avoids having an additional bulky mechanism to rotate the fiber independently of the catheter.


These and other advantages will be apparent from the following description and claims.





BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 shows an example of a prior art OCT system.



FIG. 2A shows an exemplary OCT system as described herein.



FIG. 2B is a schematic illustration of an OCT system as described herein.



FIG. 3A shows an exemplary graph of noise in an OCT detector vs. power.



FIG. 3B shows an exemplary graph of a breakdown of the types of noise contributing to the total noise in the graph of FIG. 3A.



FIG. 3C shows a chart including data drawn from the graphs in FIGS. 3A and 3B.



FIG. 4A is a top view of an exemplary mirror at the distal tip of an OCT catheter.



FIG. 4B is a cross-sectional side view the embodiment of FIG. 4A.



FIG. 5 shows a medical (cardiovascular) catheter system equipped with an OCT system.



FIGS. 6A and 6B show an exemplary embodiment of a fiber uptake system.



FIG. 7 shows an exemplary OCT image from an OCT system.



FIG. 8 shows a system for implementing the OCT system and catheter.



FIG. 9 shows one example of an optical circuit.



FIG. 10 is a schematic of an OCT system as described herein.



FIG. 11 illustrates one variation of a handle, including fiber management (spool) elements.



FIG. 12 illustrates one example of the distal end of a catheter as described herein.





DETAILED DESCRIPTION OF THE INVENTION

The Optical Coherence Tomography (OCT) catheters and systems described herein are configured to provide image guided intra-vascular procedures that may be particularly useful for the diagnosis and/or treatment of arterial disease. The systems may include a catheter, an umbilical connection, and a console. The system uses OCT to form an image of the intravascular environment close to the catheter cutter. FIG. 2B shows a schematic of one variations of an OCT system described in greater detail herein.


During intraluminal procedures, such as atherectomy, problems can arise as a result of failure to properly identify target tissue. By using a catheter having a common path optical fiber for OCT, proper identification of target tissue can be improved.


Referring to FIG. 2, a common-path OCT system 100 includes a laser source 102, such as a swept frequency light source. An optical fiber 104 transfers radiation from the laser source 102 to the target 114. The optical fiber 104 is in optical contact with an interface medium 106, i.e. the light exiting the optical fiber and entering the interface medium sees only one interface. In some embodiments, as shown in FIG. 2, the end of the optical fiber is embedded in the interface medium 106.


In the common-path OCT system 100, the index of refraction of the interface medium 106 is different than the index of refraction of the core of the optical fiber 104. This creates a Fresnel reflection, in which part of the light exits the core, and part of the light is reflected back. Some of the light beam that exits the optical fiber 104 will encounter the target 114 and be reflected or scattered by the target 114. Some of this reflected or scattered light will, in turn, reenter the tip of the optical fiber 104 and travel back down the fiber 104 in the opposite direction. A Faraday isolation device 112, such as a Faraday Effect optical circulator, can be used to separate the paths of the outgoing light source signal and the target and reference signals returning from the distal end of the fiber. The reflected or scattered target light and the Fresnel-reflected reference light from the fiber face can travel back to a detector 110 located at the proximal end of the optical fiber 104.


Because the reflected or scattered target light in the OCT system 100 travels a longer distance than the Fresnel reflected reference light, the reflected or scattered target light can be displaced by frequency, phase and or time with respect to the reference beam. For example, if swept-source radiation is used, then the light from the target will be displaced in frequency. The difference in displacement in phase, time or frequency between the reflected or scattered target light and the reference light can be used to derive the path length difference between the end of the optical fiber tip and the light reflecting or light scattering region of the target. In the case of swept source OCT, the displacement is encoded as a beat frequency heterodyned on the carrier reference beam. Embodiments of the above concept where the light paths in the reference and signal arms are common are called common path interferometers. Common path interferometry satisfies the requirements of a low cost disposable device, as it eliminates the separate reference arm but places no additional burden on the catheter construction.


The laser source 102 can operate at a wavelength within the biological window where both hemoglobin and water do not strongly absorb the light, i.e. between 800 nm and 1.4 μm. For example, the laser source 102 can operate at a center wavelength of between about 1300 nm and 1400 nm, such as about 1310 nm to 1340 nm. The optical fiber 104 can be a single mode optical fiber for the ranges of wavelengths provided by the laser source 102.


The core of the optical fiber 104 and the interface medium 106 can have specifically-chosen indexes of reflection such that a known magnitude of Fresnel reflection is created. For example, the indexes of reflection can be chosen such that noise in the OCT system is minimized.


Noise in OCT systems comes from at least three sources: shot noise, thermal or Johnson noise, and residual intensity noise (RIN noise). There may additionally be noise from the analog-to-digital conversion process. RIN noise comes from noise intrinsic to the light source, tends to dominate at high reference powers, and can be limited by limiting the maximum laser light intensity, working with an alternative low RIN light source (non-laser), or by using balanced detection. Thermal (Johnson) noise tends to dominate at low reference power levels, and can be avoided by working at reference power levels yielding a DC photodiode current above that of the thermal noise floor.


Shot noise dominates in between RIN noise and thermal (Johnson) noise. Shot noise is caused by statistical fluctuations in the number of photons or electrons that carry a particular signal. For a well designed system, shot noise is the limiting factor in dynamic range. The indexes of refraction of the fiber 104 and the interface medium 106 can thus be chosen such that the OCT system 100 operates close to the shot noise limit.


The shot noise limit of a particular receiver is set by the responsivity of the photodetector, the detection bandwidth desired, and the reference DC power impinging on the detector element. An exemplary graph of a noise v. power is shown in FIG. 3A with a break-down by the type of noise shown in FIG. 3B. The graphs in FIGS. 3A and 3B assume a system having 10 mW of forward power, 1550 nm center wavelength, 20 nm bandwidth, 1 MHz detection bandwidth, and a 1 A/W responsivity.


The shot noise limit is the area 301 at the bottom of the curve in FIG. 3A, at which the noise is the lowest or where the degradation from the shot noise limit is the least. Using the graph for a particular receiver, such as the graphs shown in FIG. 3A and FIG. 3B, the desired power at the detector, Pdet, can be determined that would place the noise within a desired range of the shot noise limit. For example, FIG. 3C shows a table of values drawn from FIG. 3B. Referring to FIG. 3C, a power of 0.158 μW would place the receiver at the minimum degradation point, 2.36 dB above the shot noise limit. Moreover, reference powers of between 63.1 nW and 251 nW would place the noise within 3 dB of the shot noise limit. Reference powers of between about 25 nW to 0.631 μW would place the noise within 5 dB of the shot noise limit.


To determine the total power, Pout, that must be reflected from the interface 106 to obtain the desired Pdet, the losses of the detector 110 must be taken into account according to Equation 1:

Pdet=Pout(1−L)  (equation 1)

where Pout is the power reflected from the reference interface, and L is the sum of the optical losses from the distal end of the probe to the detector 110. Therefore, assuming that Pdet is equal to 0.2 μW (rounding from the 0.158 μW determined to place the noise as low to the shot noise limit as possible) and that the intermediate optical system operates at 90% efficiency such that L is 10%, Pout is equal to 0.2 μW/(0.9)=0.2222 μW.


The forward power at the distal end of the optical fiber prior to entering the interface medium is given by Pin. Therefore, assume that that Pin is equal to 10 mW.


Moreover, Pout and Pin can be used to determine the reflectivity of the reference interface 180, according to equation 3:

Pout=Pinr2  (equation 3)

where r is the Fresnel coefficient of reflectivity. Therefore, assuming that Pout is 0.2222 μW, and Pin is 10 mW, as solved for via equations 2 and 3, then r is equivalent to 0.004714.


Moreover, the Fresnel equation (shown by equation 4) governs the intensity of reflection from a normal or near normal interface:









r
=

(



n
1

-

n
2




n
1

+

n
2



)





(

equation


4

)








where the index of refraction of the transparent medium is given by n2 and that of the core is n1.


The index of refraction of the core of the optical fiber, n1, is fixed by the manufacturer, and varies depending upon the fiber. The optical fiber can be, for example, a Corning SMF-28e, Corning ClearCurve, OFS BF05717 and EZBend, Fujikura SR-15e with enhanced band loss resistance, Draka BendBright XS and BendBright Elite. For Corning SMF-28e, the group refractive index of the core at 1.3 microns is 1.4677. By comparison, a Fujikura ImageFiber has n1=˜1.500.


Therefore, assuming that |r| is 0.004714 as solved for with respect to equation 3 and that n1, is 1.4677, the index of refraction of the interface medium n2 should be approximately 1.4816 or 1.4539. Thus, an interface medium of either index will produce the desired reference reflection. In some embodiments, the medium with the higher index of refraction may be preferable as it may be more readily available and/or have better mechanical properties, such as tensile strength.


The interface medium used with system 100 can be, for example, an adhesive. Depending upon the required index of refraction, the interface medium can be, for example, M21-CL which is a thermal curing adhesive. Another exemplary interface medium is the Light Weld® UV curable photonics adhesive OP-4-20658, produced by Dymax corporation, Torrington CT This adhesive, which has a refractive index of 1.585 in the cured state, is a rigid clear UV-curable adhesive that can be applied in a liquid form, and which then cures to a rigid form within seconds of exposure to UV light. Another exemplary transparent medium is EpoTek OG127-4 or OG116, produced by Epoxy Technology, Billerica MA This has a refractive index of 1.602 in the cured state.


If an interface medium having the exact refractive index desired cannot be found (for example because it does not have the proper tensile strength or is not biocompatible), an interface medium having a refractive index that is close can be selected and the power in, Phin, can be adjusted accordingly. Using the known r and the desired power at the detector, Pdet, the required power in Pin can then be determined according to equation 5:

Pdet=Pinr2(1−L)  (equation 5)


In some implementations, the interface medium can be applied in a semi-liquid state, such as by dispenser, ink jet deposition, spraying, painting, dipping, or other process. The medium may then be cured to a solid form, such as by UV curing, thermal curing, chemical curing, drying, or other process. Other processes, such as vacuum deposition of transparent medium or direct mechanical placement of the transparent medium may also be used.


The interface medium can have a minimum thickness (i.e. depth between the end of the optical fiber and the end of the interface medium) of at least








λ
min


2

π


,





where λmin is the wavelength of light in the optical fiber. For a wavelength of over 1250 nm, this will be approximately 200 nm or greater. The interface medium can also have a thickness that is great enough to introduce an offset between the reference reflection and the minimum distance that the target can approach the distal exit face of the fiber.


Referring back to FIG. 2 and to FIGS. 4A and 4B, the mirror 180 must be properly designed and optimized in order to fit into the small (approximately 2 mm) diameter of the catheter head and to reflect into a blood vessel tissue located up to 1-3 mm away from the side of the distal catheter tip. As shown in FIG. 4B, the mirror 180 can include a silicon die 401 having a reflective coating 403. The reflective coating 403 can be, for example, a gold coating. The reflective coating 403 can be greater than








λ
min


2

π


,





where λmin is the wavelength of light in the optical fiber. For example, the metallic coating can be greater than about 2,800 Å thick.


Further, the surface of the silicon die 401 under the reflective coating 403 can be polished to less than 400 nm peak-to-peak roughness, such as better than 300 nm peak-to-peak roughness, for example about 200 nm peak-to-peak roughness. An adhesive, such as nickel, titanium, or chromium, can be used to adhere the gold coating to the silicon die. The adhesive can be between about 50 Å and 200 Å thick, such as about 100 Å thick. The mirror 180 of this configuration can be at least 95% reflective, such as 98% reflective.


The mirror 180 can be placed on a slope such that it is at an angle of between 30° and 60°, such as 45° with respect to a longitudinal axis 405 of the core of the optical fiber 104. Moreover, the mirror 180 can be configured such that the total distance that the light travels from the fiber 104 to the mirror 180 and out to the sample is between 100 and 400 μm, such as between 200 and 250 μm.


As shown in FIGS. 3A and 3B, the imaging system described herein can be used with a catheter, such as an atherectomy catheter 502. An opening 2610 can be formed in the catheter 502, exposing the distal end of the fiber 104. The OCT mirror 180 can be placed in the opening near the distal tip of the catheter 104, and the interface medium can cover or embed the fiber 502, groove 2608, and opening 2610.



FIG. 5 shows an overview of the main components of an OCT imaging system 500 including a fiber optic catheter 502. The catheter 502 can be sized to fit into a blood vessel, e.g. can be about 2 mm in diameter. In this configuration, the OCT optical apparatus 504 (including the light source, optical circulator, and detectors) can be located at the proximal end of the catheter 502, and can be connected to an image processor and a display 506. The distal end of the catheter 502 includes the image fiber and the mirror. The system 500 is designed to be used within the body of a patient for various medical purposes, such as atherectomy. Thus, other components, such as a vacuum 510, aspiration control 508, and a debris reservoir 512 may be useful.


The system described herein may be used to produce relatively narrow angle images of a portion of an interior lumen of a human body, such as the interior of a blood vessel. Looking at a section of a tissue through a single OCT optical fiber is limited in that the useful angle of view produced by a single OCT optical fiber is at most a few degrees. In order to produce a more medically useful panoramic view of a wide arc or swath from the interior of a blood vessel, such as 45°, 90°, 120°, or more, the catheter containing the optical fiber can be rotated.


Referring to FIGS. 6A and 6B, the catheter 502 can be attached to a fiber uptake system 600. The optical fiber 604 can extend through the catheter 502 and can be attached at the distal end of the catheter 502. The fiber 604 can otherwise be allowed to float freely through the catheter 502, e.g., can be attached only at the distal end of the catheter 502. Doing so prevents build up of optical losses due to microbending or stress-induced birefringence. Further, the fiber 604 can be located off the central longitudinal axis of the catheter 502.


The fiber management system 600 incorporates the fiber on a single internal take-up spool 606. The take-up spool is configured with grooves 608 (see FIG. 6A) sized to fit the optical fiber 604. The optical fiber 608 can move up and down in the grooves 608 (i.e. radially with respect to the catheter 502) to compensate for any bending or stretching of the catheter 502.


The uptake system 600 further includes a physical limiter 610 configured to prohibit the take-up spool from rotating further than the OCT fiber 602 is configured to stretch. Moreover, a torque control knob 614 can be attached to the proximal end of the catheter 502. The knob 614 can be used to actuate rotation of the catheter, and thus rotation of the fiber 604. For example, the knob 614 can be manually activated. The knob 614 can also be motor-driven by a proximal controller 618 to provide a more controlled sector sweep of the imaging element. The knob 614 can be configured such that one rotation of the knob 614 causes the catheter 502 and optical fiber 604 to rotate more than once. For example, the optical fiber 604 can rotate about the longitudinal axis at least two times, such as about four times for every single rotation of the catheter 502.


An encoder 612 in the uptake system 600 detects angle and constantly relays information regarding rotation of the fiber 604 back to the computer controlling the OCT data acquisition system. This value of the angle is incorporated into the display algorithm so as to show a 360 degree view of the inside of the lumen.


Rather than having an encoder 612, the controller 618 can include a “mouse chip” position sensor similar to those used in a computer optical mouse in order to look at the catheter and encode angular and longitudinal motion. The mouse chip can be configured to look at the surface of the catheter (or the braid if the outside laminate is transparent or translucent) and calculate the X and Y motion vectors on the basis of the difference in feature position between adjacent snap-shots.


Rotating the proximal end of the catheter by 360° does not necessarily lead to a 360° rotation at the distal tip, particularly if the catheter is experiencing distributed friction over its length, for example from the introducer sheath, guides, tissue friction especially in a tight lesion. By using a mouse chip, rotation and longitudinal motion of the catheter can be detected while eliminating the unsupported length effect.


An exemplary image or display of a catheter 502 in a lumen 702 is shown in FIG. 7. The display can be continually refreshed by rotating the catheter in either direction. The whole display can also be rotated and oriented with respect to the fluoroscopic view being acquired simultaneously in the cath lab using X-ray. For example, the image may be rotated so that the pericardium is “Up” or “Down”. By orienting the display and knowing the spatial relationship between the catheter and the display (and by implication the critical physiological structures in the vessel), the physician may orient the device as required, e.g. to cut an occlusion properly.


The OCT system 100 described herein can produce images, e.g. images of tissue morphology, having a resolution of around 6-15 microns, e.g. 8-10 microns, and to depths of 1-2 mm depending on the optical properties of the sample being imaged. The axial resolution of the OCT system can be about ten times higher than that of a similar ultrasound system.



FIG. 8 shows a system 2700 for implementing the OCT system and catheter described herein. A power supply 2713 supplies power to the OCT engine 2703, the computer processor 2707, and the optical system 2711. A trigger 2701 in the OCT engine 2703 is connected to a trigger 2705 in the computer processor 2707 to begin processing of the image. Moreover, the catheter handle encoder 2715 is attached to the computer processor 2707 to transfer signals related to the location and rotation of the optic fiber. The OCT detector 2717 is attached to the computer processor 2707 to process the final image. Finally, a video signal is sent from the computer processor 2707 to a monitor 2709 to output the image to the user.


In some embodiments, the OCT system and catheter described herein can image up to 1-2 mm in depth with resolutions around 8-10 microns, sufficient to give the physician highly detailed images almost to the cellular organization level and visibility beyond the maximum cut range of the catheter. Moreover, the OCT atherectomy catheter described in can advantageously have imaging capability with crossing-profile impact that is much smaller than traditional OCT systems and ultrasound transducers.


EXAMPLE

In one example, an image-guided interventional catheter (e.g., an OCT catheter as described above) may be used to address unmet needs in peripheral and coronary artery disease (atherosclerosis). The system may include a console having a modest footprint and in a cath lab without need for extensive integration into cath lab systems. In some variations, the systems described herein may be integrated with other catheter (e.g., guidance, control, imaging) systems. The system may be configured to allow a procedure to start/proceed/finish under fluoro guidance in the event of a system failure. The system is also configured to be compatible with sterile procedures.


As mentioned above, the OCT systems described herein may allow real-time information on intravascular lesion morphology and device orientation in the vessel. This and other features may also allow improved navigation precision around complex anatomy (e.g., bifurcations, ostials, tortuosity, cutting on a curve, etc.), and around stent struts. The catheters may be safely used to traverse diseased tissue while reducing incidence of perforations and dissections potentially associated with a more aggressive treatment strategy. The systems may also provide immediate assessment of acute procedural success, and a reduction in procedure time compared to contemporary interventional techniques. The systems described herein may allow imaging of vessel wall morphology in real time and at a level of precision that could assist the physician in making a “diseased/not-diseased” determination.


In one example, the OCT system is configured to allow tissue morphology to be imaged in real time with resolution routinely around 8-10 microns, and to depths of 1-2 mm depending on the optical properties of the tissue. The axial resolution of OCT is sufficiently high that the images presented to the operator substantially resemble histology from optical microscopy, and are as a result more intuitively interpreted than ultrasound or MRI/CT images. The depth to which OCT can image through tissue with minimal to moderate lipid content is sufficient to give the physician visibility beyond the maximum proposed depth of cut for an atherectomy catheter, allowing the safety margins of the putative cut to be assessed.


As mentioned, OCT has several other technical and economic advantages for catheter applications. The impact on catheter crossing profile of the OCT optical fiber is much smaller than for even the smallest comparable ultrasound transducer. The axial resolution of OCT is typically 10× higher than ultrasound; this translates directly to image interpretability. The limited depth of penetration of typical OCT devices is not of primary concern in this application in many applications, because it is known from prior atherectomy procedures that substantial clinical benefit can be obtained by removing several hundred micron thicknesses of tissue. The depth of penetration may be matched to the expected maximum cut depth. Regions of particularly deep or thick tissue (target tissue to be removed) may be identified and treated serially or separately. For example, highly lipid-rich tissues (necrotic cores) appear as dark voids in OCT images, typically with bright caps.


The center wavelength for the optical system may be chosen to provide sufficient depth of penetration, as well as compatibility with the components of the system. For example, the OCT systems may use light that can be transmitted through fused silica fiber optics (where the primary investment in cost and quality has been made). The wavelength range to 250-2000 nm may be particularly useful. Single mode fibers can be readily obtained at any of these wavelength ranges, although wavelengths above 400 nm may be preferable. Other wavelengths could be used, but there may be significant toxicity issues with fiber materials transmitting further into the infrared, and optical sources with the appropriate properties may be difficult to obtain. Below 250 nm air-guiding fibers may be used, however these may be less desirable. In this example, we assume a range of between about 250-2000 nm.


It may be easier to “see” through small annuli of either blood, saline or mixtures by restricting the scan range of the source to regions where hemoglobin and water do not strongly absorb light. This leads to the use of a “biological window” between about 800 nm and 1.4 microns.


The dominant mechanism restricting penetration depth in biological tissue when using ballistic optical scattering techniques is the photon scattering cross-section in the tissue. Higher scattering cross-sections causes fewer photons to traverse from source to target and back ballistically, that is with only one scattering event at the target leading to a reduction in useful signal. The scattering cross-section scales as an inverse power of wavelength over the 250-2000 nm range, transitioning from an exponent of −4 at shorter wavelengths to a smaller value at longer wavelengths. The value decreases monotonically going from short to longer wavelengths so, if our need is to see deeper in tissue, the wavelength range of the source should be biased to longer wavelengths. However, this choice is not without compromise. Moving to longer wavelengths may require a more sophisticated laser source to achieve the same resolution compared to imaging at shorter wavelengths, however this is a soluble technical problem.


In some variations the system takes advantage of the widespread availability of cheap, high quality parts. For example, fiber-based telecommunications has evolved at three specific center wavelength ranges; 800 (LAN only), 1310 (O-band) and 1550 nm (C-band). The systems described herein may restrict the choice of center wavelength to 1310 nm, however this does not mean that the other two wavelength ranges could not be made to work. For example, the 800 nm center wavelength range is routinely used in ophthalmology, where depth of penetration can be sacrificed for tissue layer resolution and where fiber delivery is not a requirement (free-space optics may be used).


In some variations, the system works in the telecommunications O-band. In practice the range of center wavelength is 1315-1340 nm may be dictated by the availability of suitable laser sources in the O-band.


There are three primary categories of source/detector combinations in OCT, namely Time-Domain, Spectral-Domain (Fourier Domain or Spectral Radar) and Swept Source OCT. The examples of OCT systems described herein are swept source OCT (SS-OCT), which allow for video-rate imaging, few or no moving parts, a simple optical system suitable for fiber implementation, imaging to depths greater than 1 mm, and insensitivity to the rigors of a mobile environment.


As discussed above, several interferometer configurations may be used. The systems described herein are Common Path Interferometry (CPI) systems. This has several advantages given the goal of catheter based imaging with cost-constrained capital equipment and disposable devices. The SS-OCT with CPI system described herein preserves the Fellgett Advantage. Fellgett's advantage or the multiplex advantage is an improvement in spectroscopic techniques that is gained when an interferometer is used instead of a monochromator or scanning delay line. The improvement arises because when an interferometer is employed, the radiation that would otherwise be partially or wholly rejected by the monochromator or scanning delay line in its path retains its original intensity. This results in greater efficiency. This embodiment contrasts this with the other systems, in which only a small fraction of the laser power is useful at any given time. For example, the Lightlab™ M2 system uses TD-OCT with a scanning delay line, which is equivalent for the purposes of the Fellgett Advantage to a monochromator. Clinically, the Fellgett advantage impacts imaging speed (frame update rate), allowing significant improvements in video display rates which translate to a reduction in ambiguity in interpreting the image.


The CPI systems described herein also preserve the Jacquinot Advantage. The Jacquinot advantage states that in a lossless optical system, the brightness of the object equals the brightness of the image. Assuming that losses due the optical components are negligible, an interferometer's output will be nearly equal in intensity to the input intensity, thus making it easier to detect the signal. This translates directly to image quality, and a more interpretable image.


The CPI system as described herein therefore makes highly efficient use of the laser power. Light is either used for the reference reflection or impinges on the tissue and is used to create signal. No light is lost in attenuators or additional optical components or unused reciprocal paths. This efficient use of laser power is most apparent in the ability of the system to display clinically relevant images of the intravascular environment in real time, without the need for extensive post processing or even on-the-fly image correction.


Furthermore, these systems are “down-lead insensitive”, allowing the connection from catheter to console to be of almost arbitrary length without forcing a matched reference delay line to be shipped with each catheter. This minimizes the additional cost impact of the imaging components added to the catheter. It also allows a console component to be positioned almost anywhere, minimizing the potential disruption to work flow and minimizing the threat to a sterile field.


The systems described herein also minimize the number of optical components in the imaging system which could contribute to chromatic aberration. This minimization preserves the spectral fidelity of the laser source optimizing the layer resolution. This translates directly to image quality, and a more interpretable image.


The common-path systems described herein also have exceptional phase stability. Path length changes affecting the sample arm (temperature changes, stress-induced birefringence etc) also affect the reference arm identically. The distance from the ZPD (zero-pathlength difference) point (the reference plane) to the sample is physically fixed and is not subject to variability due to turbulence. This exceptional phase stability coupled with the exceptional phase stability of the OCT engine means that the Z-axis of the display (depth) has minimal jitter, in turn maximizing the real-time interpretability of the image. It also allows us to perform mathematical manipulation of the data that would otherwise be impossible. For example, one advantage of the systems described herein is the ability to perform pre-FFT averaging, which lowers the overall noise floor of the system again translating directly to image quality and interpretability.


In one example, the catheter is around 2 mm in diameter (7F compatible). In a saline-filled lumen, the system will be able to detect an interface (e.g., vessel wall) at 2 mm from the OD of the catheter. In this variation, the following parameters may be used for the catheter and system:
















Specifications
Value




















Optimized Detector Bandwidth
DC-10
MHz



Nyquist/Shannon rate
20
MHz










Minimum number of points to
630



sample for full resolution










The detector may detect optical modulation on the carrier wave from DC to at least 10 MHz with no roll-off in sensitivity. To prevent aliasing (which complicates image interpretation) we may digitize the detector output at a minimum of 20 M-Samples/sec (Nyquist limit) to preserve interpretable real time imaging capability. We may thus capture at least 630 points per laser pulse at this digitizer rate to avoid undersampling the available laser bandwidth.


A practical resolution target is the intima of healthy coronary artery. The system resolution is capable of showing the intima (endothelial layer+internal elastic lamina) as a single sharp bright line on the display.


The system may have an impulse response of 8-10 microns. This resolution dictates the laser scan range requirements and the bandwidth requirements of all the optical components in the fiber harness through the equation:








z

=



2

ln

2

π




λ
0
2


n

Δ

λ








Where δz is the axial resolution, λ is the wavelength, Δλ is the wavelength range over which the laser scans, n is the refractive index of the medium and the other symbols have their usual meaning. The origin of this relationship is the Heisenberg Uncertainty Principle. Several observations accrue from this equation.


If the laser scan range Δλ is not broad enough, δz (the resolution) is compromised and an image of a step refractive index discontinuity will be blurred out over many pixels. If any of the optical components in the system restrict (alternatively called clipping or vignetting) the effective bandwidth of the system is reduced and the resolution may suffer. Since the resolution equation has the center wavelength squared in the numerator, as we move to longer center wavelengths for the reasons described above, commensurately larger laser scan range may achieve equivalent axial resolution. Ophthalmology is routinely performed at 800 or 1000 nm center wavelength where there is no need to image deeply into the retina but where the available lasers allow extremely high resolution of the layers of the retina (down to 1-2 microns thickness).


In some variations, the OCT system has a scan range of >100 nm. The theoretical resolution of this engine is 6.35 microns in a medium with a refractive index of 1.35. Stipulating that we digitize at least at the Nyquist limit, fully sample the scanned bandwidth, and that the rescaling procedure in the software does not distort the data, the theoretical resolution of this system is sufficient to show the intima of a healthy coronary at the impulse response limit.


The choice of 1310 nm as a center wavelength for the laser means that we may use standard commercial off-the-shelf telecommunications components which have guaranteed performance at this wavelength and for which standardized test protocols exist. Reasonable and customary incoming inspection procedures can be used to verify that the components going into the system will not deteriorate image quality.


As mentioned above, the system may include receiving electronics including a detector. Assuming that the operating center wavelength is 1315-1340 nm with a full-width half maximum responsivity of >100 nm, and that the detector operates as close as reasonably possible to the shot-noise limited regime, the system may have sufficient trans-impedance gain from the detector to allow the A/D card to operate at an input range where digitizer noise is not a dominant contributor to the noise floor of the system.


Manufacturing tolerances on the catheters will yield a range of distal tip reference reflection intensities. The detector may be configured or chosen so as not to saturate at the high manufacturing limit of the reference reflection power. In one example, the system uses a Fermionics FD80 photodiode in an FC receptacle package as the active element in the photodetector.


The system may also include a fiber harness designed to: 1) provide a low loss pathway from the laser to the catheter, 2) route signal light returning from the catheter to the detector, 3) allow the bleed-in of a red laser diode signal to allow rapid assessment of the integrity of the fiber from cable to distal tip, and 4) provide manufacturing, calibration and field service housekeeping signals to facilitate console production, validation and maintenance.


One primary component of the fiber harness may be a self-contained enclosure with bulkhead FC/APC receptacles on it and containing an optical circuit (such as the one shown in FIG. 9.


In one example, the fiber harness may be connected as: #1 Incoming OCT source (e.g., Santec) Santec output connected here. #2 Diagnostic port (OSA/Photodiode/MZI Calibration); #3 Diagnostic port (OSA/Photodiode/MZI Calibration); #4 Connection to Detector; #5 Reflected FBG Marker (Time/Wavelength Calibration Point); #6 Connection to Catheter; #7 Transmitted FBG Signal (Photodiode scope trigger); #8 Connection to red laser source. Connections may be made with single mode fiber with a cut-off of <1260 nm. The inputs/outputs do not need to be optically isolated.


In some variations, an electrical harness may be used. The electrical harness may be configured to: 1) provide isolation for the various electrical components in the imaging system; 2) distribute 110V to the OCT engine, slave monitor and computer; 3) provide regulated isolated housekeeping power at appropriate voltages and amperages to the detector, red diode laser, catheter handle azimuthal position encoder; 4) send the video signal to the remote monitor; and 5) receive the catheter handle azimuthal angle encoder signal back to the console.


Line power may enter the console through a standard IEC60320 type C14 male power cord entry connector. The power cord used may be Hospital Grade and may have a standard IEC60320 type C13 female connector at the console end. An isolation transformer can distribute LINE power to the OCT engine, slave monitor and computer through IEC standard power cords.



FIG. 10 shows one example of a schematic of an OCT system as described herein. In this example, Items with dotted perimeters are outside the main console chassis enclosure. Analog signal interconnects are to be made with RG58 (U, A/U) patch cables terminated with BNC connectors. The (Santec) Trigger Out signal is a falling edge signal (high Z) and should not be terminated in 50 ohms. The Encoder Signal should be terminated with a MiniCircuits low pass filter module at the A/D card to remove high frequency spurious noise. The Detector Signal should be terminated with a MiniCircuits low pass filter module at the A/D card to remove any noise in an irrelevant frequency range.



FIG. 11 illustrates one variation of a handle, shown schematically. FIG. 12 illustrates one example of the distal end of a catheter as described herein. In this example, the distal end of the catheter includes a fiber having a core that is embedded in a transparent medium as described above. The fiber has an OD of 0.0065″ and is polyimide coated and flat-cleaved (at 90°). The polyimide is stripped from the end to about 500 microns. The mis-match between the refractive indexes of the core and the embedding medium gives a 32-35 dB return loss after curing.


The optical fiber may have a cut-off less than 1260 nm and have single mode performance between 1270 and 1380 nm (and be manufactured compatible with SMF-28 standards). Dissimilar fibers are not preferred as they may populate higher-order spatial modes or generate spurious return loss>65 dB at any given event. The mechanical connections (pigtail and patch cable) may include a simplex cable, and an inner loose tube Teflon Aramid fiber inner annulus to prevent stretching. The outer Jacket may be 2 mm polyurethane. The connector may be a Diamond E2108.6 connector with a 0.25 dB maximum insertion loss and a −65 dB maximum return loss.


The distal tip reference reflection (mirror) may include at least one (1) reflective interface, and may have a return loss of −33.5 dB (Nominal (31-35 dB)). There may be 200-250 microns solid transparent offset from interface to minimum tissue approach point. Interceding optical discontinuities between console and catheter distal tip may be kept to less than 65 dB return loss maximum for any individual surface. The number of reflective interfaces separated by less than 8 mm may be minimized. The parameters above are exemplary only, and may be varied as understood by those of skill in the art, while still remaining in the spirit of the invention as described herein.


The examples and illustrations included herein show, by way of illustration and not of limitation, specific embodiments in which the subject matter may be practiced. Other embodiments may be utilized and derived there from, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such embodiments of the inventive subject matter may be referred to herein individually or collectively by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept, if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.

Claims
  • 1. A method of imaging an interior of a blood vessel, comprising: inserting a catheter of an optical coherence tomography catheter system into the blood vessel, the catheter including an optical fiber within an elongate body, wherein a distal end of the optical fiber is embedded within a reference medium;providing optical radiation to a core of the optical fiber using a swept-frequency source, wherein the reference medium reflects a first portion of the optical radiation back into the core and transfers a second portion of the optical radiation to a target within the blood vessel;receiving reflected optical radiation reflected by the reference medium and the target; andgenerating an image of the target based on the received reflected optical radiation.
  • 2. The method of claim 1, further comprising rotating the optical fiber to generate multiple images of the target at different angles.
  • 3. The method of claim 1, wherein the reference medium comprises a solid transparent adhesive.
  • 4. The method of claim 3, wherein the solid transparent adhesive is an epoxy.
  • 5. The method of claim 1, wherein generating the image comprises: generating a first image of a first position of the target based upon received reflected optical radiation at the first position;rotating the optical fiber about a longitudinal axis of the elongate body; andgenerating a second image of a second position of the target based upon received reflected optical radiation at the second position.
  • 6. The method of claim 1, further comprising receiving signals related to a location and a rotation of the optic fiber.
  • 7. The method of claim 1, wherein the reflected optical radiation is received by electronics that operate in a total noise range that is within 5 dB of a shot noise limit.
  • 8. The method of claim 1, wherein a mirror in an interface medium reflects the optical radiation from the optical fiber to the target.
  • 9. The method of claim 1, wherein the core has a first refractive index n1 and the reference medium has a second refractive index n2, and wherein the first refractive index n1 and the second refractive index n2 are mismatched such that:
  • 10. The method of claim 9, wherein the first refractive index n1 and the second refractive index n2 are mismatched such that: Pdet=Pout(1−L)wherein L is a sum of all optical losses from the distal end of a probe to receiving electronics and Pdet is a power at the receiving electronics.
  • 11. A method of imaging an interior of a blood vessel, comprising: inserting a catheter of an optical coherence tomography catheter system into the blood vessel, the catheter including an optical fiber within an elongate body, wherein a distal end of the optical fiber is embedded within a reference medium;providing optical radiation to a core of the optical fiber using a swept-frequency source, wherein the reference medium reflects a first portion of the optical radiation back into the core and transfers a second portion of the optical radiation to a target within the blood vessel;rotating the optical fiber relative to the target;receiving reflected optical radiation reflected by the reference medium and the target; andgenerating images of the target based on the received reflected optical radiation, wherein the images are at different angles relative to the target based on rotation of the optical fiber.
  • 12. The method of claim 11, further comprising cutting an occlusion within the blood vessel using a cutter of the catheter.
  • 13. The method of claim 11, wherein the swept-frequency source operates at a wavelength between 250 nm-2000 nm.
  • 14. The method of claim 11, wherein the swept-frequency source operates at a wavelength between 1300 nm and 1400 nm.
  • 15. The method of claim 11, wherein the optical fiber is a single mode optical fiber.
  • 16. The method of claim 11, wherein the reference medium comprises a solid transparent adhesive.
  • 17. The method of claim 16, wherein the solid transparent adhesive is a thermal or UV curable adhesive.
  • 18. The method of claim 11, wherein the optical radiation passes through a side opening of the elongate body to the target.
  • 19. The method of claim 11, wherein a proximal end of the optical fiber and the distal end of the optical fiber are fixed relative to the elongate body, and wherein a reminder of the optical fiber floats freely through the elongate body.
  • 20. A method of imaging an interior of a blood vessel, comprising: inserting a catheter of an optical coherence tomography catheter system into the blood vessel, the catheter including an optical fiber within an elongate body, wherein a distal end of the optical fiber is embedded within a reference medium;providing optical radiation to a core of the optical fiber using a swept-frequency source, wherein the reference medium reflects a first portion of the optical radiation back into the core and transfers a second portion of the optical radiation to a target within the blood vessel;rotating the optical fiber relative to the target;receiving reflected optical radiation reflected by the reference medium and the target;generating images of the target based on the received reflected optical radiation, wherein the images are at different angles relative to the target based on rotation of the optical fiber; andcutting an occlusion within the blood vessel using a cutter of the catheter.
CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 16/506,851, filed on Jul. 9, 2019, titled “OPTICAL COHERENCE TOMOGRAPHY FOR BIOLOGICAL IMAGING,” now U.S. Publication No. US-2020-0069253-A1, which is a continuation of U.S. patent application Ser. No. 15/783,800, filed on Oct. 13, 2017, titled “OPTICAL COHERENCE TOMOGRAPHY FOR BIOLOGICAL IMAGING,” now U.S. Pat. No. 10,342,491, which is a continuation of U.S. patent application Ser. No. 12/790,703, filed on May 28, 2010, titled “OPTICAL COHERENCE TOMOGRAPHY FOR BIOLOGICAL IMAGING,” now U.S. Pat. No. 9,788,790, which claims the benefit of U.S. Provisional Application No. 61/258,064, filed on Nov. 4, 2009, “OPTICAL COHERENCE TOMOGRAPHY IMAGING SYSTEMS FOR USE WITH CATHETERS AND BIOLOGICAL PROBE,” U.S. Provisional Application No. 61/222,238, filed on Jul. 1, 2009, titled “CATHETER FOR INTRALUMINAL CIRCUMFERENTIAL IMAGING WITH ROTATION ANGLE AND LONGITUDINAL POSITION ENCODING,” and U.S. Provisional Application No. 61/182,061, filed on May 28, 2009, titled “INTRAVASCULAR OCT IMAGE GUIDED INTERVENTIONS AND LESION CHARACTERIZATION,” each of which is herein incorporated by reference in its entirety.

US Referenced Citations (540)
Number Name Date Kind
3367727 Ward et al. Feb 1968 A
3908637 Doroshow Sep 1975 A
4178935 Gekhaman et al. Dec 1979 A
4487206 Aagard Dec 1984 A
4527553 Upsher Jul 1985 A
4552554 Gould et al. Nov 1985 A
4578061 Lemelson Mar 1986 A
4598710 Kleinberg et al. Jul 1986 A
4611600 Cohen Sep 1986 A
4621353 Hazel et al. Nov 1986 A
4639091 Huignard et al. Jan 1987 A
4651753 Lifton Mar 1987 A
4654024 Crittenden et al. Mar 1987 A
4681106 Kensey et al. Jul 1987 A
4686982 Nash Aug 1987 A
4691708 Kane Sep 1987 A
4729763 Henrie Mar 1988 A
4771774 Simpson et al. Sep 1988 A
4781186 Simpson et al. Nov 1988 A
4841977 Griffith et al. Jun 1989 A
4842578 Johnson et al. Jun 1989 A
4850354 McGurk-Burleson et al. Jul 1989 A
4857046 Stevens et al. Aug 1989 A
4920961 Grossi et al. May 1990 A
4926858 Gifford, III et al. May 1990 A
5000185 Yock Mar 1991 A
5002560 Machold et al. Mar 1991 A
5018529 Tenerz et al. May 1991 A
5041082 Shiber Aug 1991 A
5047040 Simpson et al. Sep 1991 A
5085662 Willard Feb 1992 A
5099850 Matsui et al. Mar 1992 A
5178153 Einzig Jan 1993 A
5182291 Gubin et al. Jan 1993 A
5190050 Nitzsche Mar 1993 A
5192291 Pannek, Jr. Mar 1993 A
5217479 Shuler Jun 1993 A
5312415 Palermo May 1994 A
5312425 Evans et al. May 1994 A
5321501 Swanson et al. Jun 1994 A
5333142 Scheps Jul 1994 A
5358472 Vance et al. Oct 1994 A
5366464 Belknap Nov 1994 A
5372601 Lary Dec 1994 A
5383460 Jang et al. Jan 1995 A
5383467 Auer et al. Jan 1995 A
5425273 Chevalier Jun 1995 A
5425371 Mischenko Jun 1995 A
5429136 Milo et al. Jul 1995 A
5431673 Summers et al. Jul 1995 A
5437284 Trimble Aug 1995 A
5449372 Schmaltz et al. Sep 1995 A
5459570 Swanson et al. Oct 1995 A
5460168 Masubuchi et al. Oct 1995 A
5465147 Swanson Nov 1995 A
5507725 Savage et al. Apr 1996 A
5507760 Wynne et al. Apr 1996 A
5507795 Chiang et al. Apr 1996 A
5517998 Madison May 1996 A
5529580 Kusunok et al. Jun 1996 A
5556405 Lary Sep 1996 A
5607394 Andersen et al. Mar 1997 A
5613981 Boyle et al. Mar 1997 A
5620426 Braithwaite Apr 1997 A
5632754 Farley et al. May 1997 A
5632755 Nordgren et al. May 1997 A
5674232 Halliburton Oct 1997 A
5676012 Ceriale Oct 1997 A
5681336 Clement et al. Oct 1997 A
5690634 Muller et al. Nov 1997 A
5722403 McGee et al. Mar 1998 A
5728148 Bostrom et al. Mar 1998 A
5749846 Edwards et al. May 1998 A
5795295 Hellmuth et al. Aug 1998 A
5807339 Bostrom et al. Sep 1998 A
5830145 Tenhoff Nov 1998 A
5836957 Schulz et al. Nov 1998 A
5843050 Jones et al. Dec 1998 A
5843103 Wulfman Dec 1998 A
5851212 Zirps et al. Dec 1998 A
5868778 Gershony et al. Feb 1999 A
5872879 Hamm Feb 1999 A
5904651 Swanson et al. May 1999 A
5907425 Dickensheets et al. May 1999 A
5935075 Casscells et al. Aug 1999 A
5935139 Bates Aug 1999 A
5938602 Lloyd Aug 1999 A
5938671 Katoh et al. Aug 1999 A
5951482 Winston et al. Sep 1999 A
5951581 Saadat et al. Sep 1999 A
5951583 Jensen et al. Sep 1999 A
5956355 Swanson et al. Sep 1999 A
5957952 Gershony et al. Sep 1999 A
5987995 Sawatari et al. Nov 1999 A
5997558 Nash Dec 1999 A
6001112 Taylor Dec 1999 A
6007530 Dornhofer et al. Dec 1999 A
6010449 Selmon et al. Jan 2000 A
6013072 Winston et al. Jan 2000 A
6017359 Gershony et al. Jan 2000 A
6027514 Stine et al. Feb 2000 A
6032673 Savage et al. Mar 2000 A
6048349 Winston et al. Apr 2000 A
6080170 Nash et al. Jun 2000 A
6106515 Winston et al. Aug 2000 A
6110164 Vidlund Aug 2000 A
6120515 Rogers et al. Sep 2000 A
6120516 Selmon et al. Sep 2000 A
6134002 Stimson et al. Oct 2000 A
6134003 Teamney et al. Oct 2000 A
6152938 Curry Nov 2000 A
6152951 Hashimoto et al. Nov 2000 A
6160826 Swanson et al. Dec 2000 A
6175669 Colston et al. Jan 2001 B1
6176871 Pathak et al. Jan 2001 B1
6183432 Milo Feb 2001 B1
6193676 Winston et al. Feb 2001 B1
6206898 Honeycutt et al. Mar 2001 B1
6228076 Winston et al. May 2001 B1
6241744 Imran et al. Jun 2001 B1
6283957 Hashimoto et al. Sep 2001 B1
6285903 Rosenthal et al. Sep 2001 B1
6290668 Gregory et al. Sep 2001 B1
6294775 Seibel et al. Sep 2001 B1
6299622 Snow et al. Oct 2001 B1
6307985 Murakami et al. Oct 2001 B1
6375615 Flaherty et al. Apr 2002 B1
6402719 Ponzi et al. Jun 2002 B1
6416527 Berg et al. Jul 2002 B1
6445939 Swanson et al. Sep 2002 B1
6445944 Ostrovsky Sep 2002 B1
6447525 Follmer et al. Sep 2002 B2
6451009 Dasilva et al. Sep 2002 B1
6451036 Heitzmann et al. Sep 2002 B1
6454717 Pantages et al. Sep 2002 B1
6454779 Taylor Sep 2002 B1
6482216 Hiblar et al. Nov 2002 B1
6482217 Pintor et al. Nov 2002 B1
6485413 Boppart et al. Nov 2002 B1
6497649 Parker et al. Dec 2002 B2
6501551 Teamey et al. Dec 2002 B1
6503261 Bruneau et al. Jan 2003 B1
6511458 Milo et al. Jan 2003 B2
6517528 Pantages et al. Feb 2003 B1
6542665 Reed et al. Apr 2003 B2
6544230 Flaherty et al. Apr 2003 B1
6546272 MacKinnon et al. Apr 2003 B1
6551302 Rosinko et al. Apr 2003 B1
6563105 Seibel et al. May 2003 B2
6564087 Pitris et al. May 2003 B1
6565588 Clement et al. May 2003 B1
6572563 Ouchi et al. Jun 2003 B2
6572643 Gharibadeh Jun 2003 B1
6575995 Huter et al. Jun 2003 B1
6579298 Bruneau et al. Jun 2003 B1
6599296 Gillick et al. Jul 2003 B1
6615071 Casscells, III et al. Sep 2003 B1
6629953 Boyd Oct 2003 B1
6638233 Corvi et al. Oct 2003 B2
6645217 MacKinnon et al. Nov 2003 B1
6657727 Izatt et al. Dec 2003 B1
6666874 Heitzmann et al. Dec 2003 B2
6673042 Samson et al. Jan 2004 B1
6687010 Horii Feb 2004 B1
6728571 Barbato Apr 2004 B1
D489973 Root et al. May 2004 S
6730063 Delaney et al. May 2004 B2
6758854 Butler et al. Jul 2004 B1
6760112 Reed et al. Jul 2004 B2
6800085 Selmon et al. Oct 2004 B2
6818001 Wulfman et al. Nov 2004 B2
6824550 Noriega et al. Nov 2004 B1
6830577 Nash et al. Dec 2004 B2
6845190 Smithwick et al. Jan 2005 B1
6852109 Winston et al. Feb 2005 B2
6853457 Bjarklev et al. Feb 2005 B2
6856712 Fauver et al. Feb 2005 B2
6867753 Chinthammit et al. Mar 2005 B2
6879851 McNamara et al. Apr 2005 B2
6947787 Webler Sep 2005 B2
6961123 Wang et al. Nov 2005 B1
6970732 Winston et al. Nov 2005 B2
6975898 Seibel Dec 2005 B2
7068878 Crossman-Bosworth et al. Jun 2006 B2
7074231 Jang Jul 2006 B2
7126693 Everett et al. Oct 2006 B2
7172610 Heitzmann et al. Feb 2007 B2
7242480 Alphonse Jul 2007 B2
7261687 Yang Aug 2007 B2
7288087 Winston et al. Oct 2007 B2
7291146 Steinke et al. Nov 2007 B2
7297131 Nita Nov 2007 B2
7311723 Seibel et al. Dec 2007 B2
7344546 Wulfman et al. Mar 2008 B2
7366376 Shishkov et al. Apr 2008 B2
7382949 Bouma et al. Jun 2008 B2
7426036 Feldchtein et al. Sep 2008 B2
7428001 Schowengerdt et al. Sep 2008 B2
7428053 Feldchtein et al. Sep 2008 B2
7455649 Root et al. Nov 2008 B2
7474407 Gutin Jan 2009 B2
7485127 Nistal Feb 2009 B2
7488340 Kauphusman et al. Feb 2009 B2
7530948 Seibel et al. May 2009 B2
7530976 MacMahon et al. May 2009 B2
7538859 Tearney et al. May 2009 B2
7538886 Feldchtein May 2009 B2
7539362 Teramura May 2009 B2
7542145 Toida et al. Jun 2009 B2
7544162 Ohkubo Jun 2009 B2
7545504 Buckland et al. Jun 2009 B2
7555333 Wang et al. Jun 2009 B2
7577471 Camus et al. Aug 2009 B2
7583872 Seibel et al. Sep 2009 B2
7616986 Seibel et al. Nov 2009 B2
7637885 Maschke Dec 2009 B2
7674253 Fisher et al. Mar 2010 B2
7682319 Martin et al. Mar 2010 B2
7706863 Imanishi et al. Apr 2010 B2
7728985 Feldchtein et al. Jun 2010 B2
7729745 Maschke Jun 2010 B2
7734332 Sher Jun 2010 B2
7738945 Fauver et al. Jun 2010 B2
7753852 Maschke Jul 2010 B2
7771425 Dycus et al. Aug 2010 B2
7776062 Bessellink et al. Aug 2010 B2
7785286 Magnin et al. Aug 2010 B2
7813609 Petersen et al. Oct 2010 B2
7821643 Amazeen et al. Oct 2010 B2
7824089 Charles Nov 2010 B2
7840283 Bush et al. Nov 2010 B1
7944568 Teramura et al. May 2011 B2
7952718 Li et al. May 2011 B2
7972299 Carter et al. Jul 2011 B2
8002763 Berthiaume et al. Aug 2011 B2
8059274 Splinter Nov 2011 B2
8062316 Patel et al. Nov 2011 B2
8068921 Prakash et al. Nov 2011 B2
8313493 Fisher Nov 2012 B2
8361097 Patel et al. Jan 2013 B2
8548571 He et al. Oct 2013 B2
8548603 Swoyer et al. Oct 2013 B2
8632557 Thatcher et al. Jan 2014 B2
8644913 Simpson et al. Feb 2014 B2
8647335 Markus Feb 2014 B2
8696695 Patel et al. Apr 2014 B2
8911459 Simpson et al. Dec 2014 B2
9125562 Spencer et al. Sep 2015 B2
9333007 Escudero et al. May 2016 B2
9345398 Tachibana et al. May 2016 B2
9345406 Spencer et al. May 2016 B2
9345510 Patel et al. May 2016 B2
9498247 Patel et al. Nov 2016 B2
9498600 Rosenthal et al. Nov 2016 B2
9557156 Kankaria Jan 2017 B2
9572492 Simpson et al. Feb 2017 B2
9592075 Simpson et al. Mar 2017 B2
9642646 Patel et al. May 2017 B2
9788790 Black et al. Oct 2017 B2
9854979 Smith et al. Jan 2018 B2
9918734 Patel et al. Mar 2018 B2
9949754 Newhauser et al. Apr 2018 B2
10052125 Rosenthal et al. Aug 2018 B2
10130386 Simpson et al. Nov 2018 B2
10244934 Tachibana et al. Apr 2019 B2
10342491 Black et al. Jul 2019 B2
10349974 Patel et al. Jul 2019 B2
10357277 Patel et al. Jul 2019 B2
10363062 Spencer et al. Jul 2019 B2
10470795 Patel et al. Nov 2019 B2
10548478 Simpson et al. Feb 2020 B2
10568520 Patel et al. Feb 2020 B2
10568655 Simpson et al. Feb 2020 B2
10722121 Smith et al. Jul 2020 B2
10729326 Spencer et al. Aug 2020 B2
10860484 Simpson et al. Oct 2020 B2
10869685 Patel et al. Dec 2020 B2
10932670 Smith et al. Mar 2021 B2
10952615 Kankaria Mar 2021 B2
10952763 Newhauser et al. Mar 2021 B2
11033190 Patel et al. Jun 2021 B2
11076773 Patel et al. Aug 2021 B2
11096717 Gupta et al. Aug 2021 B2
11134849 Simpson et al. Oct 2021 B2
11135019 Spencer et al. Oct 2021 B2
11147583 Patel et al. Oct 2021 B2
11206975 Tachibana et al. Dec 2021 B2
11224459 Patel et al. Jan 2022 B2
11278248 Christensen Mar 2022 B2
11284839 Black et al. Mar 2022 B2
11284916 Patel et al. Mar 2022 B2
20010005788 McGuckin, Jr. Jun 2001 A1
20010020126 Swanson et al. Sep 2001 A1
20020019644 Hastings et al. Feb 2002 A1
20020072706 Hiblar et al. Jun 2002 A1
20020082585 Carroll et al. Jun 2002 A1
20020082626 Donohoe et al. Jun 2002 A1
20020097400 Jung et al. Jul 2002 A1
20020111548 Swanson et al. Aug 2002 A1
20020115931 Strauss et al. Aug 2002 A1
20020138091 Pflueger Sep 2002 A1
20020147459 Bashiri et al. Oct 2002 A1
20020158547 Wood Oct 2002 A1
20030002038 Mawatari Jan 2003 A1
20030028100 Teamney et al. Feb 2003 A1
20030032880 Moore Feb 2003 A1
20030045835 Anderson et al. Mar 2003 A1
20030095248 Frot May 2003 A1
20030097044 Rovegno May 2003 A1
20030120150 Govari Jun 2003 A1
20030120295 Simpson et al. Jun 2003 A1
20030125756 Shturman et al. Jul 2003 A1
20030125757 Patel et al. Jul 2003 A1
20030125758 Simpson et al. Jul 2003 A1
20030139751 Evans et al. Jul 2003 A1
20030181855 Simpson et al. Sep 2003 A1
20040002650 Mandrusov et al. Jan 2004 A1
20040039371 Tockman et al. Feb 2004 A1
20040057667 Yamada et al. Mar 2004 A1
20040059257 Gaber Mar 2004 A1
20040082850 Bonner et al. Apr 2004 A1
20040092915 Levatter May 2004 A1
20040093001 Hamada May 2004 A1
20040147934 Kiester Jul 2004 A1
20040167553 Simpson et al. Aug 2004 A1
20040167554 Simpson et al. Aug 2004 A1
20040181249 Torrance et al. Sep 2004 A1
20040186368 Ramzipoor et al. Sep 2004 A1
20040193140 Griffin et al. Sep 2004 A1
20040202418 Ghiron et al. Oct 2004 A1
20040220519 Wulfman et al. Nov 2004 A1
20040230212 Wulfman Nov 2004 A1
20040230213 Wulfman et al. Nov 2004 A1
20040236312 Nistal et al. Nov 2004 A1
20040243162 Wulfman et al. Dec 2004 A1
20040254599 Lipoma et al. Dec 2004 A1
20040260236 Manning et al. Dec 2004 A1
20050020925 Kleen et al. Jan 2005 A1
20050021075 Bonnette et al. Jan 2005 A1
20050027199 Clarke Feb 2005 A1
20050043614 Huizenga et al. Feb 2005 A1
20050054947 Goldenberg Mar 2005 A1
20050075660 Chu et al. Apr 2005 A1
20050085708 Fauver et al. Apr 2005 A1
20050085721 Fauver et al. Apr 2005 A1
20050105097 Fang-Yen et al. May 2005 A1
20050141843 Warden et al. Jun 2005 A1
20050149096 Hilal et al. Jul 2005 A1
20050154407 Simpson Jul 2005 A1
20050159712 Andersen Jul 2005 A1
20050159731 Lee Jul 2005 A1
20050171478 Selmon et al. Aug 2005 A1
20050177068 Simpson Aug 2005 A1
20050182295 Soper et al. Aug 2005 A1
20050187571 Maschke Aug 2005 A1
20050192496 Maschke Sep 2005 A1
20050197623 Leeflang et al. Sep 2005 A1
20050201662 Petersen et al. Sep 2005 A1
20050203553 Maschke Sep 2005 A1
20050222519 Simpson Oct 2005 A1
20050222663 Simpson et al. Oct 2005 A1
20050251116 Steinke et al. Nov 2005 A1
20060011820 Chow-Shing et al. Jan 2006 A1
20060032508 Simpson Feb 2006 A1
20060046235 Alexander Mar 2006 A1
20060049587 Cornwell Mar 2006 A1
20060064009 Webler et al. Mar 2006 A1
20060084911 Belef et al. Apr 2006 A1
20060109478 Tearney et al. May 2006 A1
20060135870 Webler Jun 2006 A1
20060173475 Lafontaine et al. Aug 2006 A1
20060229646 Sparks Oct 2006 A1
20060229659 Gifford et al. Oct 2006 A1
20060235262 Arnal et al. Oct 2006 A1
20060235366 Simpson Oct 2006 A1
20060236019 Soito et al. Oct 2006 A1
20060239982 Simpson Oct 2006 A1
20060241503 Schmitt et al. Oct 2006 A1
20060244973 Yun et al. Nov 2006 A1
20060252993 Freed et al. Nov 2006 A1
20060264741 Prince Nov 2006 A1
20060264743 Kleen et al. Nov 2006 A1
20060264907 Eskridge et al. Nov 2006 A1
20070010840 Rosenthal et al. Jan 2007 A1
20070015969 Feldman et al. Jan 2007 A1
20070015979 Redel Jan 2007 A1
20070035855 Dickensheets Feb 2007 A1
20070038061 Huennekens et al. Feb 2007 A1
20070038125 Kleen et al. Feb 2007 A1
20070038173 Simpson Feb 2007 A1
20070050019 Hyde Mar 2007 A1
20070078469 Soito et al. Apr 2007 A1
20070078500 Ryan et al. Apr 2007 A1
20070081166 Brown et al. Apr 2007 A1
20070088230 Terashi et al. Apr 2007 A1
20070106155 Goodnow et al. May 2007 A1
20070135712 Maschke Jun 2007 A1
20070167710 Unal et al. Jul 2007 A1
20070196926 Soito et al. Aug 2007 A1
20070213618 Li et al. Sep 2007 A1
20070219484 Straub Sep 2007 A1
20070250080 Jones et al. Oct 2007 A1
20070255252 Mehta Nov 2007 A1
20070270647 Nahen et al. Nov 2007 A1
20070276419 Rosenthal Nov 2007 A1
20070288036 Seshadri Dec 2007 A1
20070299309 Seibel et al. Dec 2007 A1
20080004643 To et al. Jan 2008 A1
20080004644 To et al. Jan 2008 A1
20080004645 To et al. Jan 2008 A1
20080004646 To et al. Jan 2008 A1
20080015491 Bei et al. Jan 2008 A1
20080015618 Sonnenschein et al. Jan 2008 A1
20080027334 Langston Jan 2008 A1
20080033396 Danek et al. Feb 2008 A1
20080045986 To et al. Feb 2008 A1
20080049234 Seitz Feb 2008 A1
20080058629 Seibel et al. Mar 2008 A1
20080065124 Olson Mar 2008 A1
20080065125 Olson Mar 2008 A1
20080065205 Nguyen et al. Mar 2008 A1
20080095421 Sun et al. Apr 2008 A1
20080103439 Torrance et al. May 2008 A1
20080103446 Torrance et al. May 2008 A1
20080103516 Wulfman et al. May 2008 A1
20080132929 O'Sullivan et al. Jun 2008 A1
20080139897 Ainsworth et al. Jun 2008 A1
20080146942 Dala-Krishna Jun 2008 A1
20080147000 Seibel et al. Jun 2008 A1
20080154293 Taylor et al. Jun 2008 A1
20080154296 Taylor et al. Jun 2008 A1
20080177138 Courtney et al. Jul 2008 A1
20080186501 Xie Aug 2008 A1
20080207996 Tsai Aug 2008 A1
20080221388 Seibel et al. Sep 2008 A1
20080228033 Tumlinson et al. Sep 2008 A1
20080243030 Seibel et al. Oct 2008 A1
20080243031 Seibel et al. Oct 2008 A1
20080262312 Carroll et al. Oct 2008 A1
20080275485 Bonnette et al. Nov 2008 A1
20090018565 To et al. Jan 2009 A1
20090018566 Escudero et al. Jan 2009 A1
20090018567 Escudero et al. Jan 2009 A1
20090024084 Khosla et al. Jan 2009 A1
20090024085 To et al. Jan 2009 A1
20090024191 Seibel et al. Jan 2009 A1
20090028407 Seibel et al. Jan 2009 A1
20090028507 Jones et al. Jan 2009 A1
20090043191 Castella et al. Feb 2009 A1
20090073444 Wang Mar 2009 A1
20090076447 Casas et al. Mar 2009 A1
20090093764 Pfeffer et al. Apr 2009 A1
20090099641 Wu et al. Apr 2009 A1
20090125019 Douglass et al. May 2009 A1
20090135280 Johnston et al. May 2009 A1
20090137893 Seibel et al. May 2009 A1
20090152664 Tian et al. Jun 2009 A1
20090185135 Volk Jul 2009 A1
20090196477 Cense et al. Aug 2009 A1
20090196554 Irisawa Aug 2009 A1
20090198125 Nakabayashi et al. Aug 2009 A1
20090208143 Yoon et al. Aug 2009 A1
20090216180 Lee et al. Aug 2009 A1
20090221904 Shealy et al. Sep 2009 A1
20090221920 Boppart et al. Sep 2009 A1
20090234220 Maschke Sep 2009 A1
20090235396 Wang et al. Sep 2009 A1
20090244485 Walsh et al. Oct 2009 A1
20090244547 Ozawa Oct 2009 A1
20090264826 Thompson Oct 2009 A1
20090268159 Xu et al. Oct 2009 A1
20090275966 Mitusina Nov 2009 A1
20090284749 Johnson et al. Nov 2009 A1
20090292199 Bielewicz et al. Nov 2009 A1
20090306520 Schmitt et al. Dec 2009 A1
20090316116 Melville et al. Dec 2009 A1
20090318862 Ali et al. Dec 2009 A1
20100004544 Toida Jan 2010 A1
20100021926 Noordin Jan 2010 A1
20100049225 To et al. Feb 2010 A1
20100080016 Fukui et al. Apr 2010 A1
20100082000 Honeck et al. Apr 2010 A1
20100125253 Olson May 2010 A1
20100130996 Doud et al. May 2010 A1
20100198081 Hanlin et al. Aug 2010 A1
20100217245 Prescott Aug 2010 A1
20100241147 Maschke Sep 2010 A1
20100253949 Adler et al. Oct 2010 A1
20100292539 Lankenau et al. Nov 2010 A1
20100292721 Moberg Nov 2010 A1
20100312263 Moberg et al. Dec 2010 A1
20100317973 Nita Dec 2010 A1
20100324472 Wulfman Dec 2010 A1
20110023617 Yu et al. Feb 2011 A1
20110028977 Rauscher et al. Feb 2011 A1
20110040238 Wulfman et al. Feb 2011 A1
20110058250 Liu et al. Mar 2011 A1
20110060186 Tilson et al. Mar 2011 A1
20110071401 Hastings et al. Mar 2011 A1
20110092955 Purdy et al. Apr 2011 A1
20110106004 Eubanks et al. May 2011 A1
20110118660 Torrance et al. May 2011 A1
20110130777 Zhang et al. Jun 2011 A1
20110144673 Zhang et al. Jun 2011 A1
20110201924 Tearney et al. Aug 2011 A1
20110208222 Ljahnicky et al. Aug 2011 A1
20110257478 Kleiner et al. Oct 2011 A1
20110264125 Wilson et al. Oct 2011 A1
20110270187 Nelson Nov 2011 A1
20110295148 Destoumieux et al. Dec 2011 A1
20110301625 Mauch et al. Dec 2011 A1
20120002928 Irisawa Jan 2012 A1
20120238869 Schmitt et al. Sep 2012 A1
20120277730 Salahieh et al. Nov 2012 A1
20130184549 Avitall et al. Jul 2013 A1
20130331819 Rosenman et al. Dec 2013 A1
20140005534 He et al. Jan 2014 A1
20150141816 Gupta et al. May 2015 A1
20150320975 Simpson et al. Nov 2015 A1
20160144155 Simpson et al. May 2016 A1
20180207417 Zung et al. Jul 2018 A1
20190029714 Patel et al. Jan 2019 A1
20190110809 Rosenthal et al. Apr 2019 A1
20190313941 Radjabi Oct 2019 A1
20200060718 Patel et al. Feb 2020 A1
20200323553 Fernandez et al. Oct 2020 A1
20210059713 Patel et al. Mar 2021 A1
20210076949 Smith et al. Mar 2021 A1
20210177262 Spencer et al. Jun 2021 A1
20210267621 Simpson et al. Sep 2021 A1
20210330345 Newhauser et al. Oct 2021 A1
20210345903 Patel et al. Nov 2021 A1
20220007941 Kankaria Jan 2022 A1
20220031168 Patel et al. Feb 2022 A1
20220039658 Smith et al. Feb 2022 A1
20220039828 Patel et al. Feb 2022 A1
20220071656 Patel et al. Mar 2022 A1
20220079617 Gupta et al. Mar 2022 A1
20220095926 Simpson et al. Mar 2022 A1
20220125525 Spencer et al. Apr 2022 A1
Foreign Referenced Citations (79)
Number Date Country
1875242 Dec 2006 CN
1947652 Apr 2007 CN
101601581 Dec 2009 CN
202006018883.5 Feb 2007 DE
0347098 Dec 1989 EP
0808638 Nov 1997 EP
0845692 Nov 2005 EP
1859732 Nov 2007 EP
2090245 Aug 2009 EP
2353526 Sep 2013 EP
S62-275425 Nov 1987 JP
03502060 Feb 1990 JP
H05501065 Mar 1993 JP
05103763 Apr 1993 JP
06027343 Feb 1994 JP
H07184888 Jul 1995 JP
07308393 Nov 1995 JP
2002214127 Jul 2002 JP
2004509695 Apr 2004 JP
2004516073 Jun 2004 JP
2005114473 Apr 2005 JP
2005230550 Sep 2005 JP
2005249704 Sep 2005 JP
2005533533 Nov 2005 JP
2008175698 Jul 2006 JP
2006288775 Oct 2006 JP
2006313158 Nov 2006 JP
2006526790 Nov 2006 JP
2006326157 Dec 2006 JP
200783053 Apr 2007 JP
200783057 Apr 2007 JP
2007225349 Sep 2007 JP
2007533361 Nov 2007 JP
2008023627 Feb 2008 JP
2008128708 Jun 2008 JP
2008145376 Jun 2008 JP
2008183208 Aug 2008 JP
2008253492 Oct 2008 JP
200914751 Jan 2009 JP
2009509690 Mar 2009 JP
200978150 Apr 2009 JP
2009066252 Apr 2009 JP
2009201969 Sep 2009 JP
2010042182 Feb 2010 JP
2010518900 Jun 2010 JP
2011521747 Jul 2011 JP
2012533353 Dec 2012 JP
2013512736 Apr 2013 JP
2013524930 Jun 2013 JP
20070047221 May 2007 KR
2185859 Jul 2002 RU
2218191 Dec 2003 RU
WO9117698 Nov 1991 WO
WO9923958 May 1999 WO
WO0054659 Sep 2000 WO
WO0115609 Mar 2001 WO
WO0176680 Oct 2001 WO
WO2006133030 Dec 2006 WO
WO2008005888 Jan 2008 WO
WO2008029506 Mar 2008 WO
WO2008042987 Apr 2008 WO
WO2008051951 May 2008 WO
WO2008065600 Jun 2008 WO
WO2008086613 Jul 2008 WO
WO2008087613 Jul 2008 WO
WO2008151155 Dec 2008 WO
WO2009005779 Jan 2009 WO
WO2009006335 Jan 2009 WO
WO2009009799 Jan 2009 WO
WO2009009802 Jan 2009 WO
WO2009023635 Feb 2009 WO
WO2009024344 Feb 2009 WO
WO2009094341 Jul 2009 WO
WO2009140617 Nov 2009 WO
WO2009148317 Dec 2009 WO
WO2010039464 Apr 2010 WO
WO2010056771 May 2010 WO
WO2011044387 Apr 2011 WO
WO2011062087 May 2011 WO
Non-Patent Literature Citations (28)
Entry
Patel et al.; U.S. Appl. No. 17/762,815 entitled “Atherectomy catheter with shapeable distal tip,” filed Mar. 23, 2022.
PATEL.; U.S. Appl. No. 17/763,810 entitled “Occlusion-crossing devices,” filed Mar. 25, 2022.
Fernandez et al.; U.S. Appl. No. 17/747,715 entitled “Catheter device with detachable distal end,” filed May 18, 2022.
Patel et al.; U.S. Appl. No. 17/749,882 entitled “Atherectomy Catheter,” filed May 20, 2022.
Aziz et al.; Chronic total occlusions—a stiff challege requiring a major breakthrough: is there light at the end of the tunnel?; Heart; vol. 91; suppl. III; pp. 42-48; Jun. 2005.
Bayer Material Science: ; Snap-Fit Joints for Plastics; 26 pages; retrieved from the Internet: ( https://web.archive.org/web/20121119232733if_/http://fab.cba.mit.edu:80/classes/S62.12/people/vernelle.noel/Plastic_Snap_fit_design.pdf) on Sep. 26, 2018.
Choma et al.; Sensitivity advantage of swept source and fourier domain optical coherence tomography; Optics Express; 11(18); pp. 2183-2189; Sep. 8, 2003.
De Boer et al.; Improved signal-to-noise ratio in spectral-domain compared with time-domain optical coherence tomography; Optics Letters; 28(21); pp. 2067-2069; Nov. 2003.
Emkey et al.; Analysis and evaluation of graded-index fiber-lenses; Journal of Lightwave Technology; vol. LT-5; No. 9; pp. 1156-1164; Sep. 1987.
Gonzalo et al.; Optical coherence tomography patterns of stent restenosis; Am. Heart J.; 158(2); pp. 284-293; Aug. 2009.
Han et al.; In situ Frog Retina Imaging Using Common-Path OCT with a Gold-Coated Bare Fiber Probe; CFM6; San Jose, California; CLEO, May 4, 2008; 2 pages.
Leitgeb et al.; Performance of fourier domain vs time domain optical coherence tomography; Optics Express; 11(8); pp. 889-894; Apr. 21, 2003.
Linares et al.; Arbitrary single-mode coupling by tapered and nontapered grin fiber lenses; Applied Optics; vol. 29; No. 28; pp. 4003-4007; Oct. 1, 1990.
Merriam Webster; Proximal (Definition); 10 pages; retrieved from the internet (https://www.merriam-webster.com/dictionary/proximal) on Jun. 9, 2021.
Muller et al.; Time-gated infrared fourier-domain optical coherence tomography; CFM5; San Jose, California; CLEO May 4, 2008; 2 pages.
Rollins et al.; Optimal interferometer designs for optical coherence tomography; Optics Letters; 24(21); pp. 1484-1486; Nov. 1999.
Schmitt et al.; A new rotational thrombectomy catheter: System design and first clinical experiences; Cardiovascular and Interventional Radiology; Springer-Verlag; 22(6); pp. 504-509; Nov. 1, 1999.
Sharma et al.; Common-path optical coherence tomography with side-viewing bare fiber probe for endoscopic optical coherence tomography; Rev. Sci. Instrum.; vol. 78; 113102; 5 pages; Nov. 6, 2007.
Sharma et al.; Optical coherence tomography based on an all-fiber autocorrelator using probe-end reflection as reference; CWJ13; San Francisco, California; CLEO May 16, 2004; 4 pages.
Stamper et al.; Plaque characterization with optical coherence tomography. Journal of the American College of Cardiology. 47(8); pp. 69-79; Apr. 18, 2006.
Suparno et al.; Light scattering with single-mode fiber collimators; Applied Optics; vol. 33; No. 30; pp. 7200-7205; Oct. 20, 1994.
Tanaka et al.; Challenges on the frontier of intracoronary imaging: atherosclerotic plaque macrophage measurement by optical coherence tomography; Journal of Biomedical Optics; 15(1); pp. (011104-1)-(011104-8); Jan.-Feb. 2010.
Wang et al.; Common-path endoscopic Fourier domain OCT with a reference Michelson interferometer; Proceedings of the SPIE; vol. 7566; pp. 75660L-75660L-7; Jan. 2010.
Wikipedia; Hinge; 4 pages; retrieved from the internet (https://en.wikipedia.org/w/index.php?title=Hinge&oldid=479569345) on Jun. 9, 2021.
Tachibana et al.; U.S. Appl. No. 17/645,722 entitled “Atherectomy catheter drive assemblies,” filed Dec. 22, 2021.
Patel et al.; U.S. Appl. No. 17/651,573 entitled “Atherectomy catheters and occlusion crossing devices,” filed Feb. 17, 2022.
Patel et al.; U.S. Appl. No. 17/816,673 entitled “Atherectomy catheter with serrated cutter,” filed Aug. 1, 2022.
Patel et al.; U.S. Appl. No. 18/183,432 entitled “Micro-molded anamorphic reflector lens for image guided therapeutic/diagnostic catheters,” filed Mar. 14, 2023.
Related Publications (1)
Number Date Country
20220240860 A1 Aug 2022 US
Provisional Applications (3)
Number Date Country
61258064 Nov 2009 US
61222238 Jul 2009 US
61182061 May 2009 US
Continuations (3)
Number Date Country
Parent 16506851 Jul 2019 US
Child 17652073 US
Parent 15783800 Oct 2017 US
Child 16506851 US
Parent 12790703 May 2010 US
Child 15783800 US