WO2018067332A2 - Deep tissue probe with oct variable tuning - Google Patents

Abstract

An en face deep tissue probe comprising optical coherence tomography (OCT) delivered via an optical array comprising an optical deflector/collector, and one or more gradient index lenses to image a target tissue. In one embodiment, light is deflected via a non-mechanical deflector such as a KTN module, which serves as an electro-optical wave guide. A deflector/collector module is tunable to allow incident light from the OCT to be transmitted via a first and second lens for convergence into a proximal surface of the GRIN lens and onto a target volumetric tissue area. Thusly configured, the OCT probe according to the inventive subject matter may be used for deep tissue imaging at a microscopic level to access and view various anatomical features that have heretofore been inaccessible internally and instead, have relied on macro-visualization via fluoroscopy, ultrasound or other similar approaches. The OCT deep tissue probe is applicable for enhanced evidentiary confirmation of procedures involving nerve ablation and epidural treatments, among others.

Description

PATENT APPLICATION

TITLE

DEEP TISSUE PROBE WITH VARIABLE TUNING

INVENTORS

Thomas Mowery - Davis, California

Kenneth Murray - Davis, California

David Smith - Davis, California

Marinko V. Sarunic - Burnaby, British Colombia, Canada

Manish D. Kulkarni - Pleasanton, California

CROSS REFERENCE TO RELATED APPLICATIONS: This application claims the benefit of U.S. Provisional Application No. 62/398,389 filed September 22, 2016. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT: None. THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT: Not Applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC: Not

Applicable.

FIELD OF THE INVENTION

[0001] The invention relates to imaging. More particularly, the invention relates to performing optical coherence tomography (OCT) imaging through a small probe, such as a surgical needle or micro-endoscope, to support imaging of deeper tissue zones.

BACKGROUND

[0002] Modern medical procedures are often highly reliant on advanced imaging techniques that enable a physician to perform minimally invasive diagnostic and therapeutic procedures that would otherwise: (a) require major surgery, (b) would be done "blindly," or (c) would not be possible without the imaging technology. Optica l Coherent Tomography (OCT) is an advanced imaging technology capable of providing in vivo microscopic visualization of tissue. In one sense, OCT is an optical analogue of ultrasound imaging technology. However, since OCT leverages light waves rather than sound waves, the depth of view for OCT is usually 2 mm or less in tissue. For that reason, OCT has been limited in practice to applications which primarily investigate internal and external surfaces. For example, endoscopy is frequently used to insert a camera into a digestive tract, enabling a physician to view the interior of the throat, esophagus, stomach, and upper small intestines. In most of these internal endoscopic applications, an OCT imaging device may be inserted into an organic working channel (i.e., throat, esophagus, stomach, intestine, vascularity) and threaded through the organic working channel to areas of interest.

[0003] In other situations, surgical procedures may be applied outside organic working channels, directly into deep tissue areas. Access via tissue rather than an organic working channel allows a physician to provide appropriately located therapeutic treatments, e.g., nerve blocks for regional anesthesia and pain control. However, access into deep tissue is achieved primarily using very small probes or needles. Hence, the physician does not have the ability to deploy a device the size of a typical endoscope to accurately determine placement of a probe.

[0004] The need for an OCT probe capable of imaging via deep tissue procedures has been exacerbated by recent wars in Afghanistan, Iraq and elsewhere. Many soldiers have

experienced trauma from explosive devices during recent conflicts. Consequently, a soldier involved in an encounter with an explosive device may present with eye injuries where shrapnel or other foreign objects may have penetrated the soldier's eye to be found within the vitreous fluid or embedded into the retina.

[0005] Frequently, particularly on the battlefield, such optical injuries can be accompanied by other injuries which complicate treatment. For example, the cornea of the eye may become clouded and opaque from explosive blast impacts. In that scenario, the physician is unable to apply standard OCT procedures that would normally be implemented through the cornea since the OCT light beam cannot travel through the cloudy cornea. Typically, a physician would endeavor to insert a small-diameter needle with micro-forceps to retrieve a piece of shrapnel from the soldier's eye, by determining the location of the shrapnel through the cornea. When the cornea is damaged, current micro-endoscopic techniques require a physician to penetrate the eye with a larger-diameter probe to enable a view of the interior chambers of the eye, or perform procedures through the lens area. Unfortunately, a large-diameter puncture and/or operation via the lens, creates a secondary collateral injury. This method adds risk, will extend patient recovery time and could even result in blindness. Therefore, the ability to view a piece of shrapnel within a soldier's eye via a small-diameter probe inserted through the sclera would be highly desirable.

[0006] In another scenario, a patient may present with various pain symptoms. A physician may use nerve ablation techniques to treat different maladies, including those associated with the presence of acute or chronic pain. Existing nerve ablation techniques involve inserting a hypo-tube into deep tissue of the patient and somewhat blindly navigating the end of the hypo- tube near a presumed target nerve area. Navigation to the target nerve area may be based in one instance on the use of fluoroscopic imagery to identify specific skeletal features generally associated with the anticipated presence of a nerve, along with physician experience. Once the physician has navigated the end of a probe to a location where the target nerve is presumed located, the physician will employ radiofrequency (RF) pulses to deliver energy to the presumed location of the target nerve, using an RF mechanism deployed through the hypo-tube.

Navigation to the presumed location of a target nerve is determined by navigation to other anatomical landmarks which are known to typically, but not always, suggest the location of the target nerve. Since the physician is unable to confirm that the end of the hypo-tube has been navigated with precision to reach a target nerve, the physician will rely on ablation of a larger tissue region to increase the likelihood of capturing and treating the target nerve. However, increasing the area of ablation does not guarantee that the attempt to ablate the nerve will be successful since the nerve could be situated at the edges or outside of the ablated area. Due to the limitations of existing imaging and diagnostic technologies, the physician has no ability to visually confirm that the nerve has been ablated during the course of the procedure.

[0007] In still another scenario, a female patient in the process of fetal delivery may benefit from having an epidural injection to ease the pain associated with delivery. An epidural injection may be used to deliver anesthetic and therapeutic material directly into the epidural space of the spine to minimize delivery pain. The epidural space encircles the dural sac and is filled with fat tissue and small blood vessels. The dural sac surrounds and envelops the spinal cord, nerve roots, and the cerebrospinal fluid (fluid that the nerve roots are bathed in). In addition to treating pain associated with delivery, epidural injection procedures may be used to treat acute and chronic pain. [0008] During an epidural procedure, fluoroscopy (real-time X-ray) may be used for guidance of a needle as it is inserted through the skin and directed toward the epidural space. However, in many situations, as in the case of delivering an epidural during fetal delivery, the physician may forego the use of fluoroscopy and instead, perform the epidural procedure blindly, simply using touch and prior experience. Studies have indicated that medication may be misplaced when epidural injections are performed without fluoroscopy. Even with the availability of fluoroscopy and contrast agents to improve the fluoroscopic image, many medical malpractice cases have developed where a physician inserted the epidural needle and actually penetrated the dural sac, leading to severe complications.

[0009] Consequently, there exists a longstanding and unmet need for a deep-tissue probe capable of being used during epidural procedures that would provide reliable images to the physician to ensure proper positioning of the delivery needle, accurate delivery of associated treatments or medicines, and avoidance of other anatomical elements. Further, there is a long unmet and outstanding need for a medical probe wherein there exists the ability to provide a forward-looking image of tissue both before, during and after application of therapy, such as nerve ablation, epidural treatment or diagnostic procedures. Satisfaction of such a need would allow a physician to more readily and confidently locate a target tissue area (e.g., a nerve or epidural space) or foreign object embedded or located within the target tissue area. With enhanced confidence in placement of the probe and an ability to confirm the presence of a target, whether shrapnel, nerve or epidural space, the physician would be better able to more precisely ablate or treat a smaller tissue region, thereby minimizing collateral damage to other surrounding tissue. Finally, but importantly, the ability to actually image a target during surgery or treatment would allow a physician to visually confirm that the intended procedure achieved its objectives. Currently, success or lack thereof is assessed by results of the treatment based on the subjective response of the patient, which may involve certain placebo effects that might mask whether the procedure is truly effective.

[0010] In one instance, a camera achieves imaging by focusing to a particular plane or magnification of a target object by placing multiple thin lenses in a lens tube. This configuration is impractical or impossible at small scales, such as attempting to image through a cannula, e.g., a hypo-tube or needle.

[0011] Attempts to deliver an effective deep tissue imaging probe have been varied. The use of optical fiber and electronic-based sensors has been contemplated by Weber et al in US Patent Application Publication No. 2004/0010204, January 15, 2004, entitled

"ELECTRONIC/FIBEROPTIC TISSUE DIFFERENTIATION INSTRUMENTATION" herein incorporated by reference in its entirety. The disclosure of Weber et al is directed to identifying tissue types as encountered by either using optical coherence domain reflectometry or electrodes to measure the electrical properties of the tissue. The disclosure of Weber et al does not suggest or describe a means to expand the imaging area beyond the size of the fiber. Additionally, Weber et al neither suggests nor describes a means for variably tuning the imaging device to enhance and refine an image associated with a target location. [0012] The use of a light wave to interrogate tissue in a forward looking manner is described in U.S. Patent Publication No. 2005/0027199, by Clarke, entitled "TISSUE STRUCTURE

IDENTIFICATION IN ADVANCE OF INSTRUMENT" published Feb. 3, 2005, which is herein incorporated by reference in its entirety. The disclosure of Clarke relies on the placement of optical fibers aligned along a needle, scalpel or other mechanical cutting tool to transmit and receive optical information directly in front of the cutting surface, using in one instance, optical coherence domain reflectometry. The disclosure is intended to provide a device capable of alerting a medical professional or surgical robot to the presence of an upcoming tissue boundary. However, the disclosure of Clarke does not describe an ability to create a two- dimensional scan nor a resulting two-dimensional image from a single optical fiber. Clarke discloses that only an axial scan is achievable via a single fiber. The disclosure of Clarke is directed to identifying a specific tissue interface, e.g., tissue and bone, nerve, blood vessel, and does not disclose creating an image, e.g., of a nerve, blood vessel or surrounding tissue. The usefulness of the disclosed device is limited by its one-dimensional implementation along with an inherent increase in size associated with expanding size of the optical fiber bundle to increase an imaging area. Additionally, Clarke does not disclose a means for variably tuning the device to enhance and refine imagery.

[0013] U.S. Patent Application No. 2009/0069673 Al, by Tapalian et a I, entitled, "SPINAL NEEDLE OPTICAL SENSOR" having a filing date of March 17, 2008, describes an apparatus using OCT to deliver light through a needle onto tissue in front of the needle tip and collect backscattered light to determine tissue properties. The disclosure of Tapalian describes an imaging fiber optic bundle integrated with a relay GRIN lens adjacent a GRIN objective lens. The disclosure of Tapalian relies on a scanning mirror to sweep a light beam across each individual optical fiber in an optical fiber bundle and successively direct light from the probe on each of the fiber pixel faces to achieve a two-dimensional array. Hence, the two-dimensional area of the sample which may be investigated is no more than the area of the face of the optical fiber bundle. Reduction in size of the optical fiber bundle necessarily reduces the area of the sample forward of the face of the optical fiber bundle that may be imaged. Additionally, increasing the size of the optical fiber bundle to enlarge the imaged area of the sample, necessarily increases the size of the apparatus such that it may not be used comfortably in various applications where smaller needle sizes are required. The disclosure of Tapalian is unable to create a two-dimensional scan from a single optical fiber. Tapalian discloses that only an axial scan is achievable via a single fiber. Further, the disclosure of Tapalian is directed to identifying a specific tissue interface, e.g., tissue and bone, and does not disclose creating an image, e.g., of a nerve and surrounding tissue. The usefulness of the disclosed device is limited by size and inability to expand imaging area without expanding size of the optical fiber bundle. Additionally, Tapalian et al does not disclose a means for variably tuning the imaging device to enhance and refine imagery.

[0014] U.S. Patent application 13/241,755, by Brennan et al entitled, "IMAGING SYSTEMS AND METHODS INCORPORATING NON-MECHANICAL SCANNING BEAM ACTUATION" published March 19, 2012 describes an optical probe enabling OCT imaging of a target by means of a scanning beam through the optical probe. Brennan et al describes a plurality of electro-optic material segments, driven by electrodes, embedded within the optical probe. A voltage differential provided by the electrodes across the electro-optic material is capable of deflecting a light path through the electro-optic material without any moving parts, enabling a 2- dimensional scanning pattern. An example electro-optic material suggested in Brennan is a potassium tantalate niobate (KTN) crystal. Furthermore, Brennan describes focusing elements within the probe distal to the electro-optic material, including a gradient index (GRIN) lens.

[0015] While Brennan describes an OCT-based imaging probe leveraging a KTN crystal, the solutions provided create practical limitations that would prevent its use in several applications. For example, the placement of electrodes within the optical probe creates a risk of shock to the patient in the event that voltage applied to the electrodes short-circuits to the optical probe exterior. Second, in order to provide optical deflection sufficient for a forward-looking image, the electro-optic material must possess a sufficient thickness, which must reside between the electrodes. The required material thickness places a limit on the ability to reduce the size of the optical probe, rendering it potentially unusable for many applications. The shock and minimum- thickness problems may not be circumvented in Brennan by placing the electro-optic components in a larger body proximal to the optical probe. Although Brennan describes a GRIN lens distal to the electro-optic components, the GRIN lens must be essentially the same diameter as the electro-optic segment, and cannot translate a 2-dimensional scanning pattern through a meaningful length of optical probe unless the electro-optic material is embedded within the optical probe near the distal end. Additionally, Brennan et al does not disclose a means for variably tuning the imaging device to enhance and refine imagery.

[0016] In light of the above, there is a long outstanding, unmet need for a needle-based imaging system for use in small scale deep tissue medical procedures, e.g., nerve ablation, epidural placement, etc., that enables forward-facing, volumetric scanning to confidently identify needle position, the adjacent tissue types and proximity of the tip of the needle to tissues of interest. Furthermore, there is a need for such an imaging system wherein volumetric tissue scanning is achievable through the inside of a small-diameter hypo-tube. Further, there is a need for such a system wherein the imaging element may be adjusted or focused in realtime to enhance images delivered to the physician.

SUMMARY

[0017] The above described issues may be solved via application of the inventive subject matter described herein comprising a novel integration of gradient-index (GRIN) lenses and convex lenses with non-mechanical or mechanical light beam deflectors and variable focus lenses to create a medical probe having the ability to apply OCT principles in new applications, particularly for deep tissue intervention. Unlike a thin lens, which bends light at both lens surfaces, a GRIN lens, as incorporated in the design of the present invention, will bend light as it travels through the lens based upon a varying index of refraction throughout the optically- transmissive material. The variable index of refraction associated with the GRIN lens allows for the manufacture of sufficiently small lenses having flat surfaces that can emulate the optical behavior of more spherically-shaped lenses.

[0018] For various applications, the greater thickness of a gradient-index lens as compared to a spherical thin lens, can be problematic in certain designs, particularly where smaller sizes are preferred. While traditional optical mathematics rely on a thin-lens assumption, namely, that an incident light path bends at a plane with zero thickness, gradient index mathematics require that the thickness of the lens be accounted for in both the design of the lens and its placement in an optical configuration. When designing microscale optics, GRIN lens thickness may be considered a complicating factor that is weighed against the benefits of simpler construction and flat lens surfaces.

[0019] In the present invention, Optical Coherence Tomography (OCT) is employed via a probe, i.e., a needle or introducer, to access and image tissue of interest in an axial, two- dimensional and three-dimensional context. The OCT implementation, according to the inventive subject matter described herein, generates a signal using light interferometry which may then be processed to generate a two-dimensional planar image or three-dimensional volumetric image to provide tomographic visualization of internal tissue structures. The three- dimensional volumetric image is created by processing raw data signals from the OCT system within a unique and significantly reduced scale environment. [0020] In an OCT A-scan, an axial scan (i.e., a 1-dimensional line) of the sample is imaged along a single beam extending from the end of the scanner to a single point on the surface of a sample, and extending some depth into the sample. The A-scan represents reflected optical amplitude along the axis of light propagation. An A-scan does not require any movement or sweeping of the beam. The OCT probe 10 is capable of generating an A-scan during deep tissue intervention. The A-scan may be used to identify changes in tissue type during deep tissue intervention.

[0021] In an OCT B-scan, the beam is swept across a sample to capture signals that will support the production of a 2-dimensional planar slice. The B-scan cross-sectional image comprises the amplitudes of reflections represented in a gray scale or a false-color scale. The OCT probe 10 is capable of generating a B-scan during deep tissue intervention. Likewise, the B-scan may be used to identify changes in tissue type during deep tissue intervention.

[0022] C-scan refers to a section across structures at an equal optical delay. C-scans are synthesized from a three-dimensional dataset to allow the creation of a three-dimensional image of a tissue volume of interest. The OCT probe 10 is capable of generating a volumetric C-scan during deep tissue intervention. Likewise, the C-scan may be used to identify changes in tissue type during deep tissue intervention. In addition, the C-scan allows a shape to be associated with the tissue. [0023] In the present invention, OCT is a preferred imaging modality since both the outgoing light source that interrogates the tissue, and the return signal from the tissue, may travel along a single fiber optic strand. In one instance, the fiber optic strand is small enough to fit within the interior of a needle or hypo-tube, enabling a trivial A-scan of a sample. However, the mirrors and deflectors typically used in existing OCT systems to generate a B-scan are too large to fit within a small gauge needle or hypo-tube. Consequently, current medical OCT

applications rely on A-scan side-viewing applications, limiting their ability to provide rich information for all surrounding tissue. For example, when sending a curved tube through an artery, an A-scan is able to determine whether the curve of the tube is facing towards or away from the arterial wall by distinguishing a pattern generated on an artery wall from a pattern generated from passing blood cells. This methodology is typical of probes, e.g., catheters, that may be used in organic working channels, or lumens, of the body.

[0024] The inventive subject matter describes an imaging device comprising an optical coherence tomography imaging system wherein the OCT functionality may be delivered through the inside of a needle or hypo-tube, also referred to as an introducer. In one version, the OCT beam is swept using a 2-dimensional deflector wherein all light paths from the deflector refract through a series of lenses to converge at a single point. The deflector alters the angle at which the OCT beam intersects at the convergence point. The deflector may comprise an optical beam guide and micro-electrical mechanical systems (MEMS) mirrors capable of deflecting a light beam toward a target convergence point. At the convergence point, a gradient-index lens, either a rod or fiber (hereinafter, the GRIN lens) captures the OCT beam and transmits the beam out the other end of the GRIN lens. The OCT beam exits the distal end of the GRIN lens at a specific angle determined by the angle at which the OCT beam entered the GRIN lens at a proximal end and the configuration of the GRIN lens. The GRIN lens may be deployed within the interior of a hypo-tube, wherein the hypo-tube is small enough to be utilized in certain procedures where micro-endoscopy is undesirable or impossible. An external computation node and controller drive a deflector to sweep the OCT beam exiting from the GRIN lens across the entire region of a sample at a high-frequency, enabling the reconstruction of a front-facing, volumetric OCT image of the target tissue.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0025] These and other features, aspects and advantages of various embodiments of the inventive subject matter will become better understood with regard to the following description, appended claims, and accompanying figures where:

[0026] FIG. 1 is a diagram showing the components of an Optical Coherence Tomography system according to the inventive subject matter;

[0027] FIG. 2 is a schematic of a deflector-collector module according to the inventive subject matter;

[0028] FIG. 3A is a proximal view of a GRIN lens, as applicable to the inventive subject matter; [0029] FIG. 3B is a view along the length of the GRIN lens of FIG. 3A;

[0030] FIG. 3C is a distal view of the GRIN lens of FIG. 3A;

[0031] FIGS. 4A-4B are optical diagrams highlighting operational difference between thin-lens and GRIN optical components;

[0032] FIG. 5A is a detailed view of a first exemplary light path;

[0033] FIG. 5B is a detailed view of a second exemplary light path;

[0034] FIG. 6A-6C are additional proximal views of a GRIN lens illustrating different light path entry points;

[0035] FIG. 7A-7C are additional distal views of a GRIN lens corresponding respectively to FIG. 6A-6C;

[0036] FIG. 8 is a diagram of an OCT-assisted ophthalmic surgical procedure, according to the inventive subject matter;

[0037] FIG. 9A is a diagram of an OCT-assisted nerve ablation procedure, according to the inventive subject matter; and,

[0038] FIGS. 9B-9C are exemplary images illustrating an OCT-assisted nerve ablation procedure according to the inventive subject matter. [0039] Fig. 10 is an illustration of another exemplary version of the optics of an OCT probe comprising a MEMS based scanner and a variable focus length lens incorporated with a GRIN rod lens, according to the inventive subject matter.

[0040] The accompanying figures numbered herein are given by way of illustration only and are not intended to be limitative to any extent. Commonly used reference numbers identify the same or equivalent parts of the claimed invention throughout the several figures.

DETAILED DESCRIPTION

[0041] Referring to FIG. 1, an embodiment of an optical coherence tomography (OCT) deep tissue probe 10 according to the inventive subject matter is shown. A light source 12 emits a spectrum of light centered on a desired frequency that travels through a source fiber 14 to a circulator 16. The circulator 16 transmits the light signal through an input fiber 18 to a deflector-collector module 90 comprised of a means for deflection 100 and means for collection 200. The means for deflection 100 and means for collection 200 are hereinafter likewise referred to as a deflector 100 and collector 200, respectively. The source fiber 14 and input fiber 18 comprise fiber optic strand capable of transmitting a light signal in the spectrum generated by the light source 12. The input fiber 18 is affixed to a proximal end of the deflector 100, which deflects the light emitted by the input fiber 18 according to a desired pattern. In a preferred embodiment, the deflector 100 comprises a non-mechanical deflector wherein the light beam is deflected by electromagnetic bending. In another embodiment, the deflector 100 comprises a mechanical deflector, such as a MEMS mirror, where the light beam is deflected by reflection from the MEMS mirror with the MEMS mirror actuated in a manner to create a preferred scan geometry, e.g., either Lissajous or Raster scan. In another embodiment, the deflector 100 may comprise a micro-lens driven by a micromechanical pivoting structure. In still another version, the deflector 100 may comprise a rotational mechanical system. In the following discussion, the deflector 100 may comprise a non-mechanical, a mechanical, and a hybrid of both non-mechanical and mechanical features.

[0042] In operation, a computational node 40, comprising a controller 42, sends a time- varying control signal to the deflector 100, controlling a deflection angle of an emitted light beam. The controller 42 may vary the control signal to generate any number of scanning patterns, including but not limited to raster, radial, spiral, spirographic, and Lissajous scans. The light beam emitted by the deflector 100 is captured by the collector 200; the collector 200 delivers the light beam into a GRIN lens 20. The collector 200 is designed such that for a given beam of light, the deflection angle of the light beam corresponds to a unique entry mode into the GRIN lens 20, and therefore corresponds to a unique light path through and out of the GRIN lens 20. The GRIN lens 20 extends and is deployed within the lumen of a delivery tube 26. The delivery tube 26 may be a surgical needle, a micro-endoscope, and/or a hypo-tube. In certain procedures, the delivery tube 26 may also be referred to as an introducer.

[0043] Referring still to FIG. 1, a portion of the light traveling through the GRIN lens 20 will reflect on the distal surface 24 of the GRIN lens 20. The majority of light traveling through the GRIN lens 20 will exit the GRIN lens 20 through the distal surface 24 to illuminate a specific region of a sample S, with the illuminated region determined by the initial deflection angle of the light beam from the deflector 100. The sample S may be any substance a user wishes to image using OCT, including but not limited to tissue, nerves, blood vessels, arteries, veins, bone, cells and foreign objects. The illuminated sample S will back-scatter a portion of the incident light signal, wherein some of the backscattered light will re-enter the GRIN lens 20 at a selection angle equal to the output angle. Light may be backscattered from one of a plurality of sample layers at different distances from the GRIN lens 20. Therefore, light that re-enters the GRIN lens 20 will have been back-scattered from a plurality of sample layers, with each layer corresponding to a different path-length. The back-scattered light interferes with the reflected light, generating an OCT signal that travels back through the GRIN lens 20.

[0044] Referring still to FIG. 1, the OCT signal re-enters the collector 200 through the GRIN lens 20, travels through the deflector 100, and finally exits via the input fiber 18 to the circulator 16. When the signal reaches the circulator 16, the circulator 16 directs the signal to a camera 32. The camera 32 may be a photo-detector, a linear detector array, and/or a 2- dimensional detector chip. The camera 32 records the OCT signal and, in conjunction with synchronization information provided by the controller 42, and additional processing via the computational node 40, creates and transmits an image to a display 44 and a storage medium (not shown). [0045] The embodiment illustrated in FIG. 1 uses one of many possible OCT system configurations, in particular an OCT common-path configuration. The teachings of the inventive subject matter described herein apply as well to alternative OCT configurations, including a split-path configuration achievable by adding a reference arm. Furthermore, the teachings of the inventive subject matter described herein apply across all OCT domains, including but not limited to time-domain OCT, spectral-domain OCT, and swept-source OCT, achievable with modifications to the light source and/or camera.

[0046] Referring now to FIG. 2, the deflector-collector module 90 is shown in greater detail. The deflector 100 is any device capable of collecting and bending a light beam along its path to a desired angle, in a time-varying manner, to form a scanning pattern like a Lissajous, radial, spiral, spirographic or raster scan. In a preferred embodiment, the deflector is non-mechanical, bending the light beam via applied electrical-optical means. The deflector 100 accepts a light signal via an input fiber 18 at a fiber input connector 110. The deflector 100 may bend the light signal transmitted by the input fiber 18 according to any of a plurality of techniques, including mirrors, lenses, micro-electromechanical systems, gradient-index materials, or crystals. The deflector 100 is capable of deflection in two dimensions, with the deflection pattern

determined according to a control signal from the controller 42 and the properties of the deflector 100. The control signal is transmitted to the deflector 100 by the controller 42 at a control input port 120. [0047] In one embodiment, the deflector 100 comprises, in part, potassium tantalate niobate (KTN) crystals. For example, the deflector 100 may comprise a module from NTT^® Advanced Technology Corporation, wherein the module bends and deflects the light beam via electro- optic effects of a plurality of potassium tantalate niobate (KTN) crystals to create scanning functionality. Effectively, the KTN component acts as an optical wave guide. Since the amount of guiding effect can be controlled by adjusting the value of the applied voltage, dynamic and tunable optical waveguides can be enabled, allowing the KTN component of the deflector 100 to provide desired control and configuration of the sweep of the light beam.

[0048] Refractive index distributions and corresponding light field distributions for

horizontally and vertically polarized light beams associated with the invention may be modified by application of different levels of external electric fields. The synergy between vertically- polarized light and horizontally-polarized light supports differing but complementary areas of light impingement for enhancing the imagery of a target tissue. Intensity and distribution of the light fields may be controlled by adjusting the magnitude of the applied external electric field, which enables the dynamic optical waveguide afforded by the KTN component. The dynamic nature of the KTN optical waveguide allows control of the guiding effect in optical waveguides, supporting an ability to tune the OCT probe 10 to a particular use case as required. In another embodiment of the inventive subject matter, the deflector 100, comprised of the KTN component, may be disposed at distal end 24 of the delivery tube 26. [0049] In an additional embodiment, the deflector 100 comprises a mechanical deflector, such as a MEMS mirror, which acts as a micro-scanning mirror. A micro-scanning mirror is a micro-opto-electromechanical system (MOEMS) in the category of micro-mirror actuators for dynamic light modulation. Depending upon the type of micro-scanner, the modulatory movement of a single mirror can be either translatory or rotational, on one or two axes. In the first case, a phase shifting effect takes place. In the second case, the incident light wave is deflected.

[0050] Referring still to FIG. 2, the light signal emitted by the deflector 100 exits the deflector 100 through a deflector optical relay lens 130 along a first light path 310. The first light path 310 takes the shape of a collimated light beam emitted from the center of the deflector relay lens 130, but with a variable exit angle as determined by the action of the deflector 100. A single first light path 310 may therefore be described in isolation as collimated, and divergent with respect to alternative first light path segments 310. Affixed to the deflector 100 is a collector 200 that redirects each first light path 310 along a corresponding unique second light path 320 for transmittal to the GRIN lens 20. A focusing optical lens 230 is mounted between the deflector lens 130 and the GRIN lens 20. For discussion herein, the focusing optical lens 230 is used as a point of demarcation to describe each complete light path as comprised of a first light path segment 310 and second light path segment 320. The focusing lens 230 bends or refracts all diverging first light path segments 310 to converging second light path segments 320 that focally terminate in close proximity to, or on the proximal surface 22 of the GRIN lens 20. Furthermore, while each first light path 310 is collimated, each second light path 320 is refracted by the focusing lens 230 to have a focal point 325 (see FIG. 3A and FIG. 4B) on or very near the proximal surface 22 of the GRIN lens 20. In other embodiments, the position of the focusing lens 230 may be adjusted to enhance the resolution and focus on a target tissue sample.

[0051] In a preferred embodiment, the deflector lens 130 and focusing lens 230 are convex lenses wherein each side of each lens 130, 230 is shaped in convex curvature. Each lens 130, 230 is preferably aspherical to minimize aberration and create a sharper focal spot. Other lens types and arrangements may be used within the collector 200 to transmit the initial light beams and receive reflected light beams from the tissue sample S.

[0052] Referring still to FIG. 2, the GRIN lens 20 is encased within a delivery tube 26. The delivery tube 26 may comprise a surgical needle, hypo-tube, introducer or other similar apparatus designed to penetrate into an object's interior space. Furthermore, while the embodiment shown in FIG. 2 shows a GRIN lens 20 in a rod configuration, the GRIN lens 20 may alternatively take the form of a GRIN fiber. A GRIN fiber is a fiber optic strand with a gradient index core, the core possessing the same refractory properties as a gradient index lens. GRIN fibers have the added advantage of smaller diameter, greater length, and greater flexibility. Therefore, a GRIN lens 20 in the form of a GRIN fiber may be placed within the lumen of a micro-endoscope or other insertion tube that is longer and more flexible than a typical surgical needle. [0053] Referring now to FIGS. 3A-3C, third light path segments 330 through the GRIN lens 20 are shown. Referring first to FIG. 3A, due to the gradient index of refraction of the GRIN lens 20, second light path segments 320 that enter the GRIN lens 20 at the proximal surface 22 follow and create fixed, sinusoidal third light path segments 330 through the GRIN lens 20, with each third light path segment 330 through the GRIN lens 20 corresponding to a specific second light path segment 320 determined by entry point and entry angle.

[0054] Referring now to FIG. 3B, the third light path segments 330 through the interior of the GRIN lens 20 follows curves with fixed properties. First, the various third light path segments 330 that are formed from second light path segments 320 entering as shown in FIG. 3A may be described as sinusoidal path segments with the same wavelength but varying phase shifts and amplitudes. At every half-wavelength, the various path segments converge at nodes 340 before diverging again. The wavelength of a third light path 330 through the GRIN lens 20 is a fixed, known value determined by the properties of the GRIN lens 20 and independent of the frequency of light traveling through the GRIN lens 20. The GRIN lens 20 may be cut to a specific length, or pitch, that is a desired multiple of the light path wavelength. For example, a light beam entering at the proximal surface 22 of a GRIN lens 20, wherein the GRIN lens has a pitch equal to 2, will travel through exactly 2 sinusoidal cycles before exiting the distal end 24 of the GRIN lens 20.

[0055] Referring now to FIG. 3C, a distal view of the GRIN lens 20 is shown. The GRIN lens 20 is cut to a specific length to select the non-integer part of the pitch, hereinafter referred to as the pitch fraction. The pitch fraction is selectable in manufacturing to achieve the desired output properties of various fourth light path segments 350. For example, when the pitch fraction is substantially close to 0 or 0.5, the proximal end 24 of the GRIN lens 20 terminates near a node 340 resulting in maximum divergence of the fourth light path segments 350 from the GRIN lens 20. A pitch fraction of 0 results in each fourth light path 350 exiting the GRIN lens 20 at the same angle at which the corresponding second light path segments 320 entered; a pitch fraction of 0.5 results in each fourth light path 350 exiting the GRIN lens 20 at the negative of the same angle at which the corresponding second light path segments 320 entered. Due to the configuration of the GRIN lens 20 and in conjunction with the deflector 100 as shown in FIG.2, a user may cause a beam of light to travel through the GRIN lens 20 and exit at a specific output angle determined by the control signal provided by the controller 42 to the deflector 100 and the pitch fraction of the GRIN lens 20. Similarly, a user may capture light that enters the GRIN lens 20 at a specific selection angle determined by the control signal.

[0056] As previously discussed, a perceived limitation of GRIN lenses in certain optical devices is that the GRIN lenses must necessarily be thicker than their thin-lens counterparts, thus increasing the length of the optical assembly. Applications of GRIN optics in other applications accommodate or design around this limitation to enable refraction similar to an equivalent thin lens. The present invention, by contrast, positively leverages the thickness of the GRIN lens optics to a desirable effect: the linear translation of the light signal through a narrow tube in addition to the refraction of these path segments as they exit the tube. [0057] FIG. 4A is an illustration of the structure of a standard optical approach using thin lens optics, wherein a light source is focused at a focal point F of a first collimating lens A inside a lens tube T, propagating the light paths through the lens tube T, and re-focusing the light via a second collimating lens B. This results in a series of parallel light paths P between the two lenses. However, the required diameter of the lens tube T is too large to fit inside of a surgical needle, as required by the previously-mentioned applications.

[0058] Referring now to FIG. 4B, in accordance with the inventive subject matter, a tunneling effect may be achieved in a smaller diameter. The proximal surface 22 of the GRIN lens 20 is positioned at focal point 325 of the light source emitted from the collector lens 230 rather than at a fixed distance past the focal point 325. Although not collimated, the third light path segments 330 travel through the GRIN lens 20 in sinusoidal paths and exit at predictable angles from the distal surface 24 of the GRIN lens 20. In this manner, the present invention takes advantage of an ability to vary the thickness of the GRIN lens 20 to create a desired outcome, rather than an obstacle to implementation.

[0059] Referring now to FIG. 5A, an enlarged cross-sectional side view of the collector module 200 of FIG. 2 is shown directed to the lenses 130, 230. While light paths 300 have been represented by single lines in prior views, in reality the light paths 300 have a particular beam thickness wherein a photon may travel along any one of several photon routes 360 within a light path 300. Each light path 300 may be described as a plurality of photon routes 360. In general, it is understood that photons have the highest likelihood of traveling along a center photon route 360 and a lower likelihood of following an outer photon route 360 according to a Gaussian or normal distribution. In this view, a light path 300 corresponding to no beam deflection is shown as a plurality of photon routes 360 with no initial deflection. The multiple photon routes 360 pass through and leave the deflector lens 130 at no angle, and are focused by the collector lens 230 to converge at the proximal surface 22 of the GRIN lens 20. With no deflection, the photon routes 360 converge at the center of the proximal surface 22 and follow sinusoidal paths through the GRIN lens 20 with matching phase and frequency, but varying amplitude. In this embodiment, the GRIN lens 20 is shown as having a length with a pitch fraction slightly above 0.25 or 0.75, causing the photon routes 360 to focus at a desired distance/point 25 from the distal surface 24 of the GRIN lens 20.

[0060] Now referring to FIG. 5B, another enlarged view of the collector module 200 of FIG. 2 is shown. In this view, the first light path segment 310 is shown to have an upward or positive deflection, shown by a plurality of photon routes 360. Once again, the photon routes 360 leave the deflector lens 130 from its center, but this time at an angle. The photon routes 360 are deflected by the collector lens 230 to focus at the proximal surface 22 of the GRIN lens 20. In this instance, the photon routes 360 through the GRIN lens 20 are sinusoidal and possess the same frequency, but have varying amplitudes and phases. Importantly, the various photon routes 360 remain coherent throughout the length of the GRIN lens 20, enabling reliance upon predictable exit positions and angles from the distal surface 24 as a function of the pitch fraction. In this instance, the pitch fraction is slightly above 0.25 or 0.75, and the photon routes 360 exit the distal surface 24 of the GRIN lens 20 so as to converge after a fixed distance.

[0061] Referring now to FIG. 6A-6C, alternate aspects of the implementation of the alignment of GRIN lens 20 with respect to the second light path segments 320 are shown. While the inventive subject matter has heretofore been described with the second light path segments 320 converging exactly on the proximal surface 22 of the GRIN lens 20, as shown in FIG. 6A, additional convergence configurations are available to modify the properties of the operation of the OCT probe 10. For example, in FIG. 6B, the second light path segments 320 converge in front of the GRIN lens 20 and are divergent when they intersect the proximal surface 22. This premature offset convergence results in a shift of the nodes 340 towards the proximal surface 22, and may be corrected by decreasing the pitch fraction of the GRIN lens 20. Alternatively, in FIG. 6C, the second light path segments 320 are aligned to converge within the GRIN lens 20. This delayed offset convergence results in a shift of the nodes 340 towards the distal surface 24, and may be corrected by increasing the pitch fraction of the GRIN lens 20. Thus, the present invention allows the collector 200 to be modified to adjust for imperfections in the alignment process via compensatory adjustment to the desired pitch fraction.

[0062] Referring now to FIG. 7A-7C, the fourth light path segments 350 may exit the GRIN lens 20 in one of three possible configurations depending on the pitch fraction of the GRIN lens 20. The fourth light path segments 350 may exit divergently as shown in FIG. 7A, convergent as shown in FIG. 7B, or parallel as shown in FIG. 7C, depending on the selected pitch fraction. With a pitch fraction of exactly 0.25 or 0.75, the fourth light path segments 350 will exit in parallel. With a pitch fraction between 0-0.25 or between 0.5-0.75, the fourth light path segments 350 will exit divergently, with the divergence angle decreasing as the pitch fraction increases. With a pitch fraction between 0.25-0.5 or 0.75-1.00, the fourth light path segments 350 will exit convergent, with the convergence angle increasing as the pitch fraction increases. These three categories are described with pitch fractions assuming that the focal point 325 of the second light path segments 320 was aligned exactly on the proximal surface 22 of the GRIN lens 20, as previously shown in FIG. 6A. If the second light path segments 320 entered the GRIN lens 20 in a divergent or convergent configuration as shown in FIG. 6B and FIG. 6C respectively, the pitch angle necessary to achieve the same exit behavior would decrease or increase respectively, as previously described. Thus, the present invention allows the collector 200 to be modified to adjust for imperfections in the alignment process via compensatory adjustment to the desired pitch fraction. In another version according to the inventive subject matter hereof, the collector lens 230 is moveable to provide additional adjustment.

[0063] Now referring to FIG. 8, an embodiment of the inventive subject matter applied to the detection and removal of shrapnel from a subject's eye is shown. The inventive subject matter addresses a critical and urgent need to allow a physician to debride foreign body shrapnel from the eyes of soldiers suffering from blast injuries by using an approach that bypasses the cornea. The type of shrapnel debris may be organic, metallic (ferric or non-ferric), glass, or plastic. It is imperative to remove as much debris as possible, no matter how small, in order to avoid infection, fungal growth, scarring and toxic reactions. Unless the blast injury is very fresh, vitrectomy, i.e., removal of all or part of the vitreous humor from the eye, must be employed to release each fragment from the vitreous humor before manual extraction using magnets, micro forceps or a lasso. Extracting fragments otherwise will pull the vitreous humor, which is likely to cause retinal detachment, which severely impairs vision. Furthermore, debris may be in the retina or in close proximity to the retina and thus, the retina is at risk of injury from

instrumentation used. Existing clinical OCT machines are able to image the retina only through the cornea, which is the transparent front part of the eye that covers the iris, pupil,

and anterior chamber of the eye. However, according to the inventive subject matter, the invention allows OCT to be introduced into the interior of the eye via a trans-scleral penetration rather than through the cornea. Consequently, the eye can be effectively and safely debrided of shrapnel or foreign objects while the cornea is left undisturbed. A three-dimensional microscopic surgical imaging instrument based upon the inventive subject matter described herein greatly increases the safety of the shrapnel extraction procedure and avoids collateral damage and additional recovery associated with working through or removing the cornea.

[0064] Microscopic imaging through a clear cornea offers the advantage of locating even the tiniest of fragments as compared to endoscopy. However, when the cornea is opaque, a hole must be made in the cornea to utilize microscopic imaging. This approach compromises the success of potential future corneal transplants that might be required to restore the soldier's vision. Further, if the cornea is destroyed due to an injury, trans-cornea imaging techniques do not work. As previously described, Optical Coherence Tomography (OCT) is an elegant photonic imaging modality that can produce microscopic images, but is substantially limited to surface imaging applications to detect and monitor anatomical anomalies and disease processes. In an OCT-assisted optometric procedure 400 according to the inventive subject matter, the GRIN lens 20 is deployed within the lumen of a delivery tube 26 and is then inserted into the interior of an individual's eye 410 through the sclera 412. Through the GRIN lens 20 utilizing OCT as previously described, a physician is able to image the retina 414 at a desired focal plane 370 and detect a foreign object 420 embedded in the retina 414. The delivery tube 26, in this case a surgical needle, may also possesses a removal tool 430 such as a micro-forceps, lasso or magnetic retrieval tool. The physician, relying on the OCT image for orientation, is able to navigate the delivery tube 26 to the foreign object 420, acquire the foreign object 420 using the removal tool 430, and retract the delivery tube 26 while grasping the foreign object 420 to remove the foreign object from the subject's eye. By penetrating the eye 410 via the sclera 412 rather than through the lens 411, the subject will experience less trauma and faster recovery time since the entry point of the delivery tube 26 will heal more readily than removal of a portion of the subject's lens 411.

[0065] Now referring to FIGS. 9A-9C, an additional exemplary embodiment of the inventive subject matter as applied to nerve ablation is shown. During a nerve ablation procedure 500 according to the inventive subject matter described herein, the GRIN lens 20 is deployed within the lumen of a delivery tube 26 and is inserted subcutaneously into a patient's body tissue 510 near a target nerve 512. The target nerve 512 is a nerve identified as likely requiring therapeutic ablation, and may be near other biological structures 514, such as muscle tissue, fat tissue, bone or vascular tissue, that are preferably not exposed to the ablative energy. The delivery tube 26, in this case a surgical needle, would likewise comprise an ablation tool 520, such as an ablative laser or an ablative radiofrequency transmitter. The physician, relying on a pre-ablation OCT image 525 for position and orientation, an example thereof shown in FIG. 9B, is able to navigate the delivery tube 26 to the target nerve 512 and confirm that the ablation tool 520 is appropriately directed to the target nerve 512 by, in one instance, centering the target nerve 512 in the focal plane 370. Furthermore, the physician may confirm that the ablation tool 520 is properly oriented to minimize ablative damage to other biological structures 514. The physician may then ablate the target nerve 512 utilizing ablation tool 520.

[0066] In a first instance, the physician may use low power radiofrequency or laser application to diagnostically determine if the target nerve is responsible for the patient's pain. Once the offending or responsible nerve has been identified via the diagnostic procedures, the physician may then proceed to treat the nerve with ablation or other therapeutics, e.g., anesthesia medications. After ablation has been completed, the physician may inspect the ablated region and nerve 512 using a post-ablation OCT image 550 created by the OCT probe 10, an example of the image thereof shown in FIG. 9C, to confirm that the ablation was successful, or not. Ablated tissue will typically develop differential optical properties as compared to that of the original non-ablated tissue. Thus, the ablated region 555 would be differentially visible in the OCT image. Thus, rather than relying solely on subjective anecdotal response from a patient, and favorably avoiding the need to extend the lateral and volumetric range of the ablative area, the physician is able to more precisely perform the desired procedure and more directly confirm and validate its success or lack thereof. The ability to confirm successful ablation allows the physician to provide confirming evidence of success or failure for subsequent review that has heretofore been unavailable. Thus, the physician can begin to adapt treatment procedures according to empirical data to provide an appropriate level of ablation to achieve desired therapeutic results. Consequently, the physician will be able to deliver more precise treatment with significantly more granularity across a broader treatment spectrum. Equally important, is the ability to confidently confirm that a procedure successfully implemented failed to achieve the desired therapeutic results.

[0067] In use, the OCT probe 10 may be deployed as a diagnostic and therapeutic en face imaging insert in a variety of existing probes. For example, in one version, the OCT probe 10 is sized for insertion within the lumen of an 18-gauge Tuohy- type hypodermic needle.

Consequently, a physician will be able to deploy the OCT probe 10 to support precision neurosurgery for: (a) precision RF / laser ablation of nerves for facet-mediated pain; (b) precision RF / laser ablation of nerves for palliative pain relief from metastases in end-stage cancer patients; (c) precision injection of nerve modulating agents; and (d) precise placement of electrodes for neuro-modulation and neuro-stimulation. The OCT probe 10, serving as a needle imaging insert, will deliver deep tissue imaging capability with 10 - 15-micron resolution over 1 - 2 mm of penetration depth in scattering tissue, and well over a centimeter in clear tissue or fluids, including vitreous and aqueous humors.

[0068] There exist several tradeoffs when using ultrasonic waves for imaging versus optical or light waves. First, since ultrasonic waves are lower frequency, they will penetrate deeper through tissue than higher frequency light waves. However, the image quality from OCT, even with a 2D view, is much better than an ultrasound image. Ultrasound exploration and examination requires sophisticated interpretation of shadows by the physician. Hence, due to the coarser image and need for interpretative analysis, one cannot always make an absolute diagnosis using ultrasound. Thus, an abnormal ultrasound examination requires further investigation. Consequently, one could not depend on the ultrasound image to identify specific tissue targets. In contrast, microscopic analysis provides a much higher resolution image of a target volume and can be digitally interpreted to provide the physician with a somewhat clearer understanding of the resulting image.

[0069] Resolution quality of an OCT image depends on many factors, including the scan pattern associated with the sweep of the light beam. Standard OCT data acquisition usually results from a raster scan acquired from a side looking catheter probe along a horizontal path. The data acquisition pattern from the OCT probe 10 according to the inventive subject matter may be raster or Lissajous. [0070] During surgery, a physician may want to refine aspects of the area to be imaged. In one sense, the physician may want to obtain a better focused image on a particular location in the tissue. Consequently, it would be necessary to have an imaging solution that allowed realtime focal adaptation without having to remove the imaging probe. FIG. 10 is an illustration of another aspect of the inventive subject matter wherein the optics of the OCT probe 10 comprise means for varying a focal length so as to increase or decrease the working distance of the OCT probe 10.

[0071] In one version, the deflector module 100 comprises a two-dimensional MEMS scanner which delivers the OCT beam to a first relay lens 130 and a second relay lens 230 that then delivers the OCT beam to a variable focal length lens 630. The variable focal length lens 630 delivers the OCT beam to the GRIN lens 20. As shown in FIG. 10, the variable focal length lens 630 allows the working distance to be adjusted between 2 mm and 7 mm and the beam spot size to be adjusted accordingly. The ability to change the working distance and beam spot size of the OCT probe 10 in real-time provides flexibility for the physician during surgery to refine the focal area of an image.

[0072] In use, for example, for initial localization of shrapnel, the OCT probe 10 may initially be set to a longer working distance (7mm) providing approximately 20-micron lateral (x-y) resolution. By controlling the focal length of the variable focal length lens (having initial focal length of 35 mm), the working distance and beam spot size may likewise be controlled, which directly governs the lateral resolution of the acquired image. In one instance, the OCT probe 10 may leverage an 0.85 mm GRIN rod lens and variable focal length lens providing a variable working distance of between 7mm and 2mm and a lateral (x-y) resolution of between 20 microns and 10 microns, respectively.

[0073] Once an approximate location of one or more pieces of shrapnel has been determined using a longer working distance associated with the OCT probe 10, the OCT probe 10 may be moved closer to the shrapnel while the optics of OCT probe 10 may be adjusted for a higher resolution via the variable lens. In one instance, the focal length of the variable focal length lens may be changed to 34.8 mm, which provides working distance of approximately 2mm and approximate lateral resolution of 10 microns. Thus, the OCT probe 10 provides variable working distance and variable resolution in one probe, eliminating a need to remove the imaging probe to insert a different imaging probe with different optical characteristics.

[0074] The inventive subject matter may likewise be applied to deliver a longer imaging insert for standard mid-length needles as well as longer "catheter" style probes. The longer imaging insert comprises a longer GRIN lens with a curved tip wherein the needle may be rotated to view a greater volumetric area. For example, a longer imaging insert would allow for deeper penetration into the posterior chamber of the eye. The flexible long GRIN lens catheter would allow the deflector module 90 to be placed away from a sensitive or delicate area of investigation. For example, when performing surgery on the eye, placement of the deflector module 90 away from the body of the probe will reduce the weight of the surgical tool, enabling the clinician to more easily manipulate debridement efforts. [0075] The inventive subject matter is adaptable and applicable for use in various procedures associated with minimally invasive neurosurgery. For example, the OCT probe 10 may be used to support image-guided therapeutics for the neurosurgical field, including but not limited to: (a) precision injection of neurolytics near nerves; (b) radiofrequency and laser nerve ablation for palliative pain care; (c) precision placement of electrodes for neuromodulation,

neurostimulation, etc. and (d) a novel approach for epidural injections.

[0076] In one instance, the OCT probe 10 comprises an 18-gauge Tuohy-type needle designed to be used under fluoroscopy guidance. The OCT probe 10 may function as an imaging insert as opposed to a fully integrated needle so that the imaging capability is available to a physician regardless of the physician's personal needle preference. Ultimately, the OCT probe 10 will reduce health care costs due to more precise delivery of treatment, which will: (a) prevent or reduce expensive emergency room visits, (b) reduce the rate of inpatient re-admissions, (c) result in shorter patient recovery times, (d) create safer procedures and (e) create an opportunity for increasing the number of minimally invasive surgical procedures.

[0077] The OCT probe 10 according to the inventive subject matter described herein will provide physicians with the capability to precisely locate deep anatomical targets and reduce collateral damage to vital tissues such as nerves, arteries, veins and vitreous. The OCT probe 10 will reduce surgical complications including: (a) reduction in spinal cord injuries from blind cervical epidural steroid injections, (b) minimization of vitreous damage during a posterior chamber debridement, (c) preventing neuromas from blind needle injury to nerves, and, (d) minimizing collateral damage during treatment to surrounding tissues.

[0078] The OCT probe 10 according to the inventive subject matter will allow more precise therapeutic effect with minimal collateral damage during treatment. Current fluoroscopy guidance, based on a presumption of nearness to skeletal structures, may allow a physician to navigate within certain presumed proximity to a target nerve. However, the subsequent treatment therapy must anticipate and consider this inaccuracy of placement. For example, when a physician implements an ablation procedure using radiofrequency or laser heating, a significant tissue volume is heated to coagulate a larger volume with major and minor axes of several mm since the nerve could be anywhere within the zone of uncertainty.

[0079] Similarly, for the injection of neurolytics to perform a nerve block by intentionally injuring a target nerve, the injected volume must be large enough to incapacitate a volume of tissue encompassing the potential error in locating the nerve. One particular injectable used for a neuralytic block, absolute alcohol, is highly labile and mobile, and tends to diffuse through tissue, damaging any tissue it comes into contact with until being diluted down below a threshold level. In many cases, the treatment methods create such large zones of tissue necrosis that the treatment may cause as much pain as is being ameliorated by destruction of the nerve at the target site. Further, by precisely determining the location of a target nerve, which will reduce collateral damage and cause a likely reduction in post-operative pain, the need for subsequent expensive pain medicines will likewise be reduced. [0080] "Blind" intervention creates an inherent suspicion as to whether a treatment is actually being delivered as indicated. As a result, physicians may be faced with the rejection of the use or payment for procedures, which may actually be effective, simply because there is insufficient evidence to document that the procedure is actually applied as presumed. The OCT probe 10 will allow the physician to document accuracy of the procedure and provide evidentiary validation to support reimbursement to the physician. There is always an inherent error rate in "blind" interventions, which by default will result in wasted financial expenditures for procedures. The OCT probe 10 will ameliorate suspicion associated with blind

intervention, improve treatment, and avoid wasted financial expenditures.

[0081] In the context of "pay-for-performance," the ability to confidently assess the treatment will reduce cost. "Pay-for-performance" is an umbrella term for initiatives aimed at improving the quality, efficiency, and overall value of health care. These arrangements provide financial incentives to hospitals, physicians, and other health care providers to carry out such improvements and achieve optimal outcomes for patients. Pay-for-performance has become popular among policy makers and private and public payers, including Medicare and Medicaid. The Affordable Care Act expands the use of pay-for-performance approaches in Medicare in particular and encourages experimentation to identify designs and programs that are most effective. The use of the OCT probe 10 by a physician will enhance compliance in such a payment structure and avoid wasted time by the physician and wasted payment by the payor. [0082] The OCT probe 10 will reduce patient re-admission rate by offering more precision in initial surgeries and reducing the need for hospital-based procedures. It is often the case that despite the nominal overtreatment resulting in collateral damage described above with radiofrequency ablation and use of neurolytics, the nerve is only temporarily incapacitated at time of surgery and subsequently recovers. Ultimately, the pain returns and results in an early re-admit of the patient to the hospital or ambulatory care center. This is obviously

inconvenient and unfortunate for the patient, and is not well-received by the insurance company paying for the additional procedure. The OCT probe 10 will reduce the need for hospital surgeries by using minimally invasive surgical procedures to reduce the number of post-operative complications. This will avoid early re-admission to the hospital, which will also avoid the penalty cost to the hospital.

[0083] The OCT probe 10 can use various technologies within the deflector 100, including spirograph, KTN, MEMS, et al. The OCT probe 10 can be used to support medical procedures such as: (a) intra-cardiac plaque ablation; (b) intra-ocular surface approach to monitoring disease progression such as macular degeneration; (c) documenting cancer margins; (e) neuro- implantation; and, (f) anesthesia and nerve blocks for pain.

[0084] In the above procedures, particularly anesthesia and nerve blocks, an objective of the inventive subject matter described herein is to accurately visualize tissue-enveloped anatomical targets, such as nerves, blood vessels, joints, cancer tissue, and tumor tissue. Due to the unavailability of an effective imaging solution, anesthesiologists and other practitioners frequently blindly insert needles into both animal and human anatomy to diagnose and treat medical conditions or to facilitate pain-free surgical procedures. For example, to place anesthesia, an anesthesiologist may feel for a pulse in the axilla (arm pit) of a patient in order to approximate access to a nerve target complex that would numb the arm of a patient requiring surgery in that extremity. This is a blind approach, sometimes complemented by electrical stimulation, in order to place a large volume of local anesthesia in the nerve complex region. The OCT probe 10, according to the inventive subject matter, will prove beneficial to reduce the risks of such procedures by avoiding "blind" introduction of sharp cutting probes around nerves and arteries. Beside anatomical mishaps, blind introduction and intervention may result in a disproportionally high failure rate for the applied procedure. As such, treatment costs increase. Additionally, litigation associated with the medical treatment may result, increasing costs to all parties. "Blind" intervention may be assisted by fluoroscopy in specially-built costly facilities such as hospitals and outpatient surgery centers. However, the injection specialist gets target reference anatomy from boney structures, but still does not "see" the target nerves and blood vessels. The OCT probe 10 overcomes this limitation.

[0085] Thus, specific compositions of a deep tissue OCT probe 10 have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the disclosure. Moreover, in interpreting the disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms, "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

Claims

CLAIMS We hereby claim:

1. An OCT imaging probe comprising:

a. an OCT system;

b. a deflector-collector module comprising a means for deflection and a means for collection;

c. a computational node;

d. a gradient index lens;

e. a delivery tube, said gradient index lens incorporated within said delivery tube; f. an optical fiber delivering a light beam from said OCT system to an input port on said means for deflection,

g. said means for deflection adapted to sweep said light beam in a two-dimensional pattern;

h. said means for collection adapted to relay said swept light beam to said gradient index lens;

i. said light beam transmitted through said gradient index lens to scan a target; j. said target reflecting portions of said light beam back to said gradient index lens; k. said gradient index lens transmitting said reflected portions of said light beam back to said means for collection; I. said means for collection transmitting said reflected portions of said light beam back to said means for deflection;

m. said means for deflection transmitting said reflected portions of said light beam to said OCT system; and,

n. said computational node processing signals from said reflected portions of said light beam to create a digital representation of said target.

2. The probe of claim 1, wherein said means for deflection is non-mechanical and

mechanical.

3. The probe of claim 2, wherein said means for deflection comprises a plurality of

potassium tantalate niobate crystals.

4. The probe of claim 1, further comprising means for varying a focal length so as to increase or decrease the working distance of the OCT imaging probe.

5. The probe of claim 4 further comprising:

a. a first relay lens;

b. a second relay lens;

c. a variable focal length lens;

d. said means for deflection transmitting said light beam from said OCT system to said first relay lens;

e. said first relay lens transmitting said light beam to said second relay lens; f. said second relay lens transmitting said light beam to said variable focal length lens; g. said variable focal length lens delivering said light beam to said GRIN lens;

h. wherein said position of said variable focal length lens is adjustable to vary a working distance and vary a beam spot size; and,

i. said variance implemented in real-time during imaging of a target.

6. The probe of claim 1, wherein said means for deflection and said means for collection comprises an integrated module.

7. The probe of claim 1, further comprising:

a. a 3-axis lens control placed on a proximal end of said gradient index lens; and, b. said 3-axis lens control enabling calibration of said swept light beam incident on said proximal end of said gradient index lens.

8. The probe of claim 7, wherein said 3-axis lens control may adjust the distance between said means for collection and said gradient index lens to adjust the focal plane of said light beam as it exits a distal end of said gradient index lens.

9. The probe of claim 1, further comprising a therapeutic module incorporated within said delivery tube.

10. The probe of claim 9, wherein said therapeutic module comprises a fluid delivery

system, a means for ablation, and, an object retrieval mechanism.

11. A method of imaging tissue comprising an OCT system and a deep tissue probe wherein an optical fiber delivers light to a distal end of said deep tissue probe, the method comprising:

a. positioning a distal end of said deep tissue probe proximal a target to be imaged; b. providing a light beam to a deflector-collector module via an input port;

c. said deflector-collector module causing said light beam to be swept in a two- dimensional pattern;

d. transmitting said swept light beam to a gradient index lens;

e. said gradient index lens transmitting said swept light beam out a distal end of said gradient index lens to scan a target;

f. collecting reflected portions of said swept light beam from the target in said gradient index lens;

g. transmitting said reflected portions of said swept light beam through said

gradient index lens to said deflector-collector module;

h. transmitting said reflected portions of said swept light beam to the OCT system; i. processing said reflected portions of said swept light beam by a computational node to create images of said target; and,

j. displaying said images of said target to a user of said deep tissue probe;

k. adjusting a position of

12. The method of claim 11, wherein said target comprises a nerve, an epidural space, bone, a blood vessel, an artery, a vein, a retina, joints, cancer tissue, and tumor tissue.

13. The method of claim 11, wherein said deep tissue probe images a foreign object

embedded in a retina.

14. A method for OCT-assisted surgical procedures comprising an OCT system wherein an imaging probe and one or more therapeutic modules are incorporated into a delivery tube, the method comprising:

a. positioning a distal end of said delivery tube proximal a tissue sample to be

treated;

b. confirming, via said imaging probe, the proper placement and orientation of said one or more therapeutic modules within said delivery tube proximate to said tissue sample;

c. performing a therapeutic procedure on said tissue sample using said one or more therapeutic modules;

d. verifying, via said imaging probe, that said therapeutic procedure was

successfully performed on said tissue sample.

15. The method of claim 14, wherein said surgical procedure comprises treatment of one or more nerves.

16. The method of claim 14 wherein said surgical procedure comprises gaining access and entry into one or more blood vessels.

17. The method of claim 14, wherein one of said one or more therapeutic modules

comprises a means for ablation, a means for retrieval of a foreign body, and, a means for delivery of a fluid.

18. The method of claim 15, wherein said step of verifying comprises inspecting said nerve to validate that a portion of said nerve has been treated.

19. The method of claim 14, wherein said surgical procedure comprises removal of a foreign body.

20. The method of claim 14, wherein said step of verifying step comprises validating that said means for foreign body retrieval has successfully extracted a foreign body.