1. Field of the Disclosure
The technology of the disclosure relates to low coherence interferometric (LCI) systems and methods for the imaging of scattering samples and the measurement of their optical and structural properties.
2. Technical Background
Examining the structural features of cells is essential for many clinical and laboratory studies. The most common tool used in the examination for the study of cells has been the microscope. Although microscopic examination has led to great advances in understanding cells and their structure, it is inherently limited by the artifacts of preparation. The characteristics of the cells can only be seen at one moment in time with their structural features altered because of the addition of chemicals. Further, invasion is necessary to obtain the cell sample for examination.
Thus, light scattering spectrography (LSS) was developed to allow for in vivo examination applications, including cells. The LSS technique examines variations in the elastic scattering properties of cell organelles to infer their sizes and other dimensional information. In order to measure cellular features in tissues and other cellular structures, it is necessary to distinguish the singly scattered light from diffused light, which has been multiply scattered and no longer carries easily accessible information about the scattering objects. This distinction or differentiation can be accomplished in several ways, such as the application of a polarization grating, by restricting or limiting studies and analysis to weakly scattering samples, or by using modeling to remove the diffused component(s).
As an alternative approach for selectively detecting singly scattered light from sub-surface sites, low coherence interferometry (LCI) has also been explored as a method of LSS. LCI utilizes a light source with low temporal coherence, such as a broadband white light source for example. Interference is achieved when the path length delays of an interferometer are matched with the coherence time of the light source. The axial resolution of the system is determined by the coherent length of the light source and is typically in the micrometer range suitable for the examination of tissue samples. Experimental results have shown that using a broadband light source and its second harmonic allows the recovery of information about elastic scattering using LCI. LCI has used time depth scans by moving the sample with respect to a reference arm directing the light source onto the sample to receive scattering information from a particular point on the sample. Thus, scan times were on the order of five (5) to thirty (30) minutes in order to completely scan the sample.
Angle-resolved LCI (a/LCI) has been developed as a means to obtain sub-surface structural information regarding the size of a cell. In this regard, light is split into a reference beam and a sample beam, wherein the sample beam is projected onto the sample at different angles to examine the angular scattering distribution of scattered light. The a/LCI technique combines the ability of LCI to detect singly scattered light from sub-surface sites with the capability of light scattering methods to obtain structural information with sub-wavelength precision and accuracy to construct depth-resolved tomographic images. Structural information is determined by examining the angular scattering distribution of the back-scattered light using a single broadband light source mixed with a reference field with an angle of propagation.
The a/LCI technique has been successfully applied to measuring cellular morphology and to diagnosing intraepithelial neoplasia in an animal model of carcinogenesis. The a/LCI method of obtaining structural information about a sample has been successfully applied to measuring cellular morphology in tissues and in vitro as well as diagnosing intraepithelial neoplasia and assessing the efficacy of chemopreventive agents in an animal model of carcinogenesis. a/LCI has been used to prospectively grade tissue samples without tissue processing, demonstrating the potential of the technique as a biomedical diagnostic.
Embodiments disclosed in the detailed description include optical fiber-based angle-resolved low coherence interferometric (LCI) (a/LCI) systems and methods that can be employed for the imaging of scattering samples and the measurement of their optical and structural properties. The a/LCI systems and methods disclosed herein can employ a single-mode collection optical fiber that is scanned at a multitude of scattering angles with respect to the sample of interest to collect an angular scattering distribution of scattered light from the sample. Use of a single-mode collection optical fiber to collect an angular scattering distribution of scattered light from the sample can provide several non-limiting advantages. In certain embodiments, only one (1) single-mode collection optical fiber is employed.
For example, a multi-mode optical fiber collection bundle can be employed that includes a plurality of optical fibers each configured to collect a particular angle of scattering of light from the sample. The collection of angles of scattering of light from the sample can provide an angular scattering distribution of scattered light from the sample to provide depth-resolved spectral information about the sample. However, providing a plurality of multi-mode optical fibers in an optical fiber collection bundle can be more costly. Further, modal dispersion issues can be present from the use of multi-mode optical fibers, thereby reducing the accuracy of the interference produced by the cross-correlation of a reference signal with a scattering of light signal from a sample. To minimize issues than can arise from modal dispersion, the length of each of the multi-mode optical fibers can be precisely controlled to be the same length such that the few modes are excited in the multi-mode optical fibers. However, this precise length control may be more costly. Use of a single-mode optical fiber collection bundle can also be employed, but providing a plurality of single-mode collection optical fibers is more costly than employing one single-mode collection optical fiber. Further, by providing a scanning of the single-mode collection optical fiber about the sample, the a/LCI systems and methods disclosed herein may be compatible with standard optical coherence tomography (OCT) systems, which may permit the a/LCI systems to directly incorporate equipment already developed for OCT systems. Further, using a single-mode collection optical fiber in an a/LCI system, a single channel spectrometer can be employed to receive the angle-resolved, cross-correlated sample signal rather than an imaging spectrometer, resulting in a simplified and compact system design and reduce cost, as examples.
In this regard, in certain embodiments disclosed herein, a light source is provided. A reference signal and a sample signal are split from a light emitted by the light source. The sample signal is directed towards a sample of interest at an angle. The single-mode collection optical fiber can be translated relative to the optical axis of the sample to collect various angular scatterings of light from the sample at a multitude of scattering angles. In this regard, the single-mode collection optical fiber can be scanned at the multitude of angles about the sample to collect various scattered sample light from the sample at the multitude of scattering angles. The collected scatterings of scattered sample light from the sample are mixed or cross-correlated with the reference signal to provide a cross-correlated signal with the interference term. The cross-correlated signal can then be spectrally dispersed by a spectrometer to yield a spectrally-resolved, cross-correlated signal having depth-resolved information about the sample at the given scan angle of the single-mode collection optical fiber. Thus, by scanning the single-mode collection optical fiber at a multitude of angles with respect to the sample, an angular scattering distribution of the spectrally-resolved, cross-correlated signals at each scattering angle can be determined and provided. Thus, the angular scattering distribution of the spectrally-resolved, cross-correlated signals can be processed by a control system to determine size characteristics about the sample.
Further, the angular scattering distribution of the spectrally-resolved, cross-correlated signals can be Fourier transformed to produce depth information and characteristics about the sample. In this instance, the a/LCI system and method can be characterized as a Fourier domain a/LCI (fa/LCI) system and method. Various mathematical techniques and methods are provided for determining size and/or depth information about the sample. Other embodiments of a/LCI systems employing a single-mode collection optical fiber are also disclosed. Non-interferometric systems employing a single-mode collection optical fiber are also disclosed.
These methods, processes, techniques, and systems disclosed herein offer an opportunity to significantly improve the standard of care for patients and decrease overall health care costs by diagnosing and treating tissue conditions, including pre-cancerous and cancerous conditions, in vivo. The methods, processes, and techniques disclosed herein effectively reduce the treatment time to the time of a first medical procedure on the patient, thus providing earlier treatment and potentially better and more timely results at a lower cost. This also provides more accurate diagnosis and determination of treatment effectiveness since the monitoring is performed on a localized level with the ability to diagnose, treatment, and monitor the affected tissue during the same or concomitant medical procedure or examination. The above-described methods, processes, techniques, and systems also enable more efficient diagnosis, treatment, and monitoring, or throughput of patients. This may be particularly important where health facilities and appointments are a limited resource.
The a/LCI systems and methods described herein can be clinically viable methods for assessing tissue health without the need for tissue extraction via biopsy or subsequent histopathological evaluation. The a/LCI systems and methods described herein can be applied for a number of purposes: for example, early detection and screening for dysplastic tissues, disease staging, monitoring of therapeutic action, and guiding the clinician to biopsy or surgery sites. The non-invasive, non-ionizing nature of the optical biopsy based on an a/LCI probe means that it can be applied frequently without adverse affect. The potential of a/LCI to provide rapid results will greatly enhance its widespread applicability for disease screening.
In addition to clinical activities, a real time optical biopsy such as a/LCI can be used in research activities, particularly those that track tissue health over time, such as in the study of chemo-preventatives. Real time a/LCI could be used to scan a tissue sample or cell culture at various points in time to assess changes in the status of the tissue or cells. For example a cell culture of cancer cells could be scanned and then treated with a chemo-preventative and then scanned at subsequent time points to see if the cancer cells were killed (such as by apoptosis) or not.
Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description that follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.
Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all embodiments are shown. Indeed, the concepts may be embodied in many different forms and should not be construed as limiting herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.
Embodiments disclosed in the detailed description include optical fiber-based angle-resolved low coherence interferometric (LCI) (a/LCI) systems and methods that can be employed for the imaging of scattering samples and the measurement of their optical and structural properties. The a/LCI systems and methods disclosed herein can employ a single-mode collection optical fiber that is scanned at a multitude of scattering angles with respect to the sample of interest to collect an angular scattering distribution of scattered light from the sample. In certain embodiments, only one (1) single-mode collection optical fiber is employed. Use of a single-mode collection optical fiber to collect an angular scattering distribution of scattered light from the sample can provide several non-limiting advantages.
For example, a multi-mode optical fiber collection bundle can be employed that includes a plurality of optical fibers each configured to collect a particular angle of scattering of light from the sample. The collection of angles of scattering of light from the sample can provide an angular scattering distribution of scattered light from the sample to provide depth-resolved spectral information about the sample. However, providing a plurality of multi-mode optical fibers in an optical fiber collection bundle can be more costly. Further, modal dispersion issues can be present from the use of multi-mode optical fibers, thereby reducing the accuracy of the interference produced by the cross-correlation of a reference signal with a scattering of light signal from a sample. To minimize issues than can arise from modal dispersion, the length of each of the multi-mode optical fibers can be précised controlled to be the same length such that the few modes are excited in the multi-mode optical fibers. However, this precise length control may be more costly. Use of a single-mode optical fiber collection bundle can also be employed, but providing a plurality of single-mode collection optical fibers is more costly than employing one single-mode collection optical fiber. Further, by providing a scanning of the single-mode collection optical fiber about the sample, the a/LCI systems and methods disclosed herein may be compatible with standard optical coherence tomography (OCT) systems, which may permit the a/LCI systems to directly incorporate equipment already developed for OCT systems.
In this regard,
In this embodiment, the reference arm 22 connects the ten percent (10%) ports of both FC114 and FC216 using a pair of collimators C130 and C232. In this embodiment, C130 is mounted on a linear translation stage 34 to allow for adjustment of path length of the reference arm 22 for path length matching of the reference arm 22 to the sample arm 24. In this regard, as discussed below, a portion of the reference arm 22 contains free space optics that allow easy adjustment of the reference arm 22 for path length matching of the reference arm 22 to the sample arm 24. The intensity of the reference arm 22 can also be adjusted by insertion of a neutral density filter (NDF) 36. The sample arm 24 in this embodiment arranges the two (2) ninety percent (90%) ports of FC114 and FC216 in reflection mode. The port from FC114 illuminates a sample 38 of interest with the sample signal 28 split from the light signal 18. The port from FC216 collects the backscattering or scattering of light from the sample 38, or scattered sample light 40, as a result of illuminating the sample 38 with the sample signal 28, respectively.
The reference signal 26 and the scattered sample light 40 are then mixed at FC216 to generate interference for detection by a detector 42, which in this embodiment is an optical fiber-coupled miniature spectrometer 43. For example, the spectrometer 43 may be the HR4000 spectrometer manufactured by OceanOptics which contains a linear sensor with 3648 pixels. Because the angular scattering distribution of the scattered sample light 40 is polarization dependent in this embodiment, the incident polarization is controlled in order to effectively use Mie scattering models for data analysis. A polarization controller (PC) 44 is used to evenly distribute the sample signal 28 energy into p- and s-polarizations so that the Mie model based analysis can be implemented as the average of the two orientations. If linear polarization is desired, it can be achieved by the use of an in-line fiber polarizer and polarization-maintaining fibers and couplers.
With continuing reference to
In this embodiment, the collection optical fiber 48 is a single-mode optical fiber. Further, only one (1) single-mode optical fiber is provided in the collection optical fiber 48 in this embodiment. Thus, the collection optical fiber 48 is translated perpendicular to the optical axis of the sample 38 to collect different angles of scattered sample light 40 from the sample 38, as opposed to a fiber optic bundle that comprises a plurality of optical fibers that would each be arranged to collect different angles of scattered sample light 40 from the sample 38 in parallel. In this regard, the collection optical fiber 48 may be coupled to a motorized actuator 54 to acquire the angular scattering distribution of the scattered sample light 40 (block 68 in
For convenience, θ is defined as the supplement of the conventional scattering angle (i.e., θ=0 radians (rad) corresponds to backscattering). The inter-fiber distance d between the illumination optical fiber 29 and the collection optical fiber 48 is scanned through a range (e.g., 0.25 mm, 1.35 mm) at a given speed (e.g., 0.1 mm/second (s)) collecting spectra at a multitude of angles with respect to the optical axis of the sample 38 (e.g., approximately one hundred sixteen (116) angles in twelve (12) seconds). This scanning profile results in a useful range (e.g., 0.27 mm, 1.23 mm, or 0.088 rad, 0.406 rad) correspondingly, and an angular resolution (e.g., 0.0032 rad). As will be discussed in more detail below, the collection of the angular scattering distribution of the scattered sample light 40 from the sample 38 can provide depth-resolved spectral information about the sample 38 that can be processed and analyzed by a control system 45 to determine size and/or depth characteristics about the sample 38.
Use of the single-mode collection optical fiber 48 to collect an angular scattering distribution of the scattered sample light 40 from the sample 38 can provide several non-limiting advantages. For example, a multi-mode optical fiber collection bundle could be employed that includes a plurality of optical fibers each configured to collect a particular angle of scattered sample light 40 from the sample 38 in
The cross-correlated signal 53 enters the spectrometer 43 and is spectrally dispersed (block 70 in
I(k,θ)=Ir(k)+Is(k,θ)+2η√{square root over (Is(k,θ)Ir(k))}{square root over (Is(k,θ)Ir(k))}cos[Δφ(k,θ)] (1)
where Ir(k) is the reference arm intensity at wavenumber k and is independent of d and θ; Is(k, θ) is the scattered sample light 40 from the sample 38 at angle θ; Δφ(k,θ) is the phase difference between the two fields; and η is a factor reflecting the system coupling efficiency and interference efficiency, which is assumed to be a constant. In the a/LCI system 10 of
To obtain optimized depth resolution, the spectral dispersion of the cross-correlated signal 53 can be compensated prior to Mie theory analysis. This can be done based on the fact that the dispersion is the nonlinearity of Δφ(k,θ), or equivalently δφ(k,θ)=Δφ(k,θ)−kL, where L is the wavelength-independent best estimate of the optical path length difference between the reference and sample arms. To find L in this embodiment, the interference is first recorded using a mirror as sample and obtain the unwrapped phase Δφ′(k,θ), which differs from actual phase difference Δφ(k,θ) by 2mπ where m is a positive integer. Thus,
δφ(k,θ)=Δφ′(k,θ)+2mπ−kL (2)
Equation (2) is a least squares fitting problem that can generate an initial estimate of m and L. m is rounded to the nearest integer, [m], and used as a known parameter in Equation (2) for another linear regression to find the best estimate of L. The dispersion δφ(k,θ) then follows accordingly. Since the scanning single-mode collection optical fiber 48 alters the sample arm 24 path only minimally, it is assumed δφ(k,θ) is independent of θ, and hence apply the same dispersion compensation to all angles θ.
In a mirror experiment, it was found to be sufficient for the a/LCI system 10 in
Depth and angular detection range are also important parameters for an a/LCI probe. An efficient method to evaluate these parameters can be provided by the use of a “scattering standard” that generates uniform angular scattering intensity across the probe's angular range (e.g., such as the 0.26 μm microspheres) (e.g., manufactured by Thermo Fisher Scientific, Inc. with a 10% standard deviation). The microspheres can be suspended in a density-matching mixture of eighty percent (80%) water and twenty percent (20%) glycerol and used to fill a one (1) mm-thick chamber sandwiched by a No. 1 coverslip and a microscope slide. To avoid detecting reflection from the interfaces by the single-mode collection optical fiber 48, the sample 38 is slightly tilted out of plane.
The depth-resolved sizing capability of the scanning single-mode optical fiber probe 46 can be demonstrated using a double-layer phantom. In this regard,
In summary, the Fourier-domain a/LCI technique for determining size and depth characteristics of a sample can be based on a scanning of a single-mode optical fiber probe and a modified Mach-Zehnder interferometer, as provided by the example of the a/LCI system 10 in
The MZI-based a/LCI system 10 in
With reference to
In this embodiment, the MSHI 122 is based on a single-mode fiber optic coupler (polarization-maintaining fibers and couplers if necessary). As illustrated in
With continuing reference to
The signals' relative optical path lengths (OPLs) are illustrated in
L
1
−L
2=2d (3)
where d is determined by the focal length and thickness of the lens, usually a few millimeters at least. As a result, all other signals, except for R1, S12 and S21, are far apart in OPL and in practice will not generate interference to be detected by Fourier-domain LCI.
As an example, the single-mode optical fibers 127, 129 can be cleaved and their facets are placed in the focal plane of a lens 134, which may be a graded index (GRIN) lens (e.g., Newport Corp.: 0.23 pitch, 1.8 mm diameter; 4.4 mm length) for illumination and collection. The lens 134 can be angled at eight degrees (8°), for example, on the sample 133 side to avoid or reduce the collection of specular reflection from the sample 133. The majority of source power is coupled into single-mode optical fiber 129, which serves as the illumination optical fiber. Its output is collimated via the lens 134, illuminating the area of interest on the sample 133. The single-mode optical fiber 127 is the low power arm and serves as the collection fiber that receives the light scattered at angle θ. To maximize the detectable angular range, the single-mode optical fiber 129 can be positioned toward the edge of the lens 134, whereas the single-mode optical fiber 127 can raster-scans in a 2D pattern using a pair of motorized actuators. The polarization of the illumination and collection fields can be tuned independently using polarization controllers 135, 139 to be linearly polarized along any direction with extinction ratio greater than 20 dB, making it possible to measure scattering under any combination of illumination and collection polarization. Return signals of the mixed sample and reference fields are detected by a miniature spectrometer.
The symmetry of this a/LCI system 120 points to the fact that R2 can also serve as the reference signal, provided that L2>L1 and equation (3) holds. The difference between the two approaches is that using the low-power arm signal R1 as the reference provides superior polarization performance to the use of the high-power arm signal R2 as the reference. These two signals propagate together and fiber disturbance has no effect. The polarization component of S21 that is detected by the interferometer is determined by the direction of the linearly polarized R1 as it exits the fiber at the single-mode optical fiber 127, a parameter that can be measured and adjusted using a polarizer and a power meter. A similar procedure can be used for adjusting the illumination polarization as well. In summary, the a/LCI system 120 allows both the illumination and the collection to be either p- (y direction) or s- (x direction) polarized, offering full polarization control and hence enabling 2D capability.
For example, single-mode optical fiber 127 raster scans an area of 1.0×1.8 mm2 (y×x), which covers the detectable area of the lens 134, with a continuous scan (e.g., 0.35 mm/sec) in x and a step scan (e.g., 10 μm/step) in y direction. To compensate for any scan nonlinearity, the data are linearly resampled in x direction prior to analysis. A complete scan can take twelve (12) minutes and generates a 2D angular scattering distribution containing 90×170 data points, with an angular resolution of 0.212°/step in both directions, as an example. At each point of the 2D distribution, the interference spectrum can be processed and Fourier-transformed into depth-resolved scattering intensity with a depth resolution of 17.7 μm, as an example. To demonstrate polarization-sensitive measurements, p-polarized illumination can be used to collect both the p- and s-components of the scattered field.
The MSHI 122 can also be applied for imaging scattering samples at a certain angle, as shown in an alternative MSHI a/LCI system 140 in
As previously discussed, the a/LCI systems described herein using a single-mode collection optical fiber may allow compatibility with OCT systems. Particularly, the a/LCI systems may be compatible with OCT systems if the fiber probes are replaced with alternative fiber probes. In this regard,
In the fiber probe 150 of
The a/LCI systems and methods described herein can be clinically viable methods for assessing tissue health without the need for tissue extraction via biopsy or subsequent histopathological evaluation. For example, the ends of the illumination optical fiber and the single-mode collection optical fiber can be disposed in a fiber probe where the fiber probe is employed in an endoscopic probe of an endoscope used to examine tissue. The a/LCI systems and methods described herein can be applied for a number of purposes: for example, early detection and screening for dysplastic tissues, disease staging, monitoring of therapeutic action, and guiding the clinician to biopsy or surgery sites. The non-invasive, non-ionizing nature of the optical biopsy based on an a/LCI probe means that it can be applied frequently without adverse affect. The potential of a/LCI to provide rapid results will greatly enhance its widespread applicability for disease screening.
Nuclear morphology measurement is also possible using the a/LCI systems and methods described herein. Nuclear morphology is a necessary junction between a cell's topographical environment and its gene expression. One application of the a/LCI systems and methods is to connect topographical cues to stem cell function by investigating nuclear morphology. In one embodiment, the a/LCI systems and methods use a swept-source light source approach described herein and create and implement light scattering models. The second is to provide nuclear morphology as a function of nanotopography. Finally, by connecting nuclear morphology with gene expression, the structure-function relationship of stem cells, e.g., human mesenchymal stem cells (hMSC), under the influence of nanotopographic cues can be established.
The a/LCI methods, processes, techniques, and systems described herein can also be used for cell biology applications and medical treatment based on such applications. Accurate measurements of nuclear deformation, i.e., structural changes of the nucleus in response to environmental stimuli, are important for signal transduction studies. Traditionally, these measurements require labeling and imaging, and then nuclear measurement using image analysis. This approach is time-consuming, invasive, and unavoidably perturbs cellular systems. The a/LCI techniques described herein offer an alternative for probing physical characteristics of living systems. The a/LCI techniques disclosed herein can be used to quantify nuclear morphology for early cancer detection, diagnosis and treatment, as well as for noninvasively measuring small changes in nuclear morphology in response to environmental stimuli. With the a/LCI methods, processes, techniques, and systems provided herein, high-throughput measurements and probing aspherical nuclei can be accomplished. This is demonstrated for both cell and tissue engineering research. Structural changes in cell nuclei or mitochondria due to subtle environmental stimuli, including substrate topography and osmotic pressure, are profiled rapidly without disrupting the cells or introducing artifacts associated with traditional measurements. Accuracy of better than 3% can be obtained over a range of nuclear geometries, with the greatest deviations occurring for the more complex geometries.
In one embodiment disclosed herein, the a/LCI systems and methods described herein are used to assess nuclear deformation due to osmotic pressure. Cells are seeded at high density in chambered coverglasses and equilibrated with 500, 400 and 330 mOsm saline solution, in that order. Nuclear diameters are measured in micrometers to obtain the mean value +/− the standard error within a 95% confidence interval. Changes in nuclear size are detected as a function of osmotic pressure, indicating that the a/LCI systems and methods disclosed herein can be used to detect cellular changes in response to factors which affect cell environment. One skilled in the art would recognize that many biochemical and physiological factors can affect cell environment, including disease, exposure to therapeutic agents, and environmental stresses.
To assess nuclear changes in response to nanotopography, cells are grown on nanopatterned substrates which create an elongation of the cells along the axis of the finely ruled pattern. The a/LCI systems and processes disclosed herein are applied to measure the major and minor axes of the oriented spheroidal scatterers in micrometers through repeated measurements with varying orientation and polarization. A full characterization of the cell nuclei is achieved, and both the major axis and minor axis of the nuclei is determined, yielding an aspect ratio (ratio of minor to major axes).
The a/LCI systems and methods disclosed herein can also be used for monitoring therapy. In this regard, the a/LCI systems and methods are used to assess nuclear morphology and subcellular structure within cells (e.g., mitochondria) at several time points following treatment with chemotherapeutic agents. The light scattering signal reveals a change in the organization of subcellular structures that is interpreted using a fractal dimension formalism. The fractal dimension of sub-cellular structures in cells treated with paclitaxel and doxorubicin is observed to increase significantly compared to that of control cells. The fractal dimension will vary with time upon exposure to therapeutic agents, e.g., paclitaxel, doxorubicin and the like, demonstrating that structural changes associated with apoptosis are occurring. Using T-matrix theory-based light scattering analysis and an inverse light scattering algorithm, the size and shape of cell nuclei and mitochondria are determined. Using the a/LCI systems and methods disclosed herein, changes in sub-cellular structure (e.g., mitochondria) and nuclear substructure, including changes caused by apoptosis, can be detected. Accordingly, the a/LCI systems and processes described herein have utility in detecting early apoptotic events for both clinical and basic science applications.
Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which the embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings.
This disclosure is not limited to any particular a/LCI arrangement. In one embodiment, the apparatus is based on a modified Mach-Zehnder interferometer, but other a/LCI interferometric arrangements are possible. Non-interferometric a/LCI arrangements are also possible.
As an alternative to processing the a/LCI data and comparing to Mie theory, there are several other approaches which could yield diagnostic information. These include analyzing the angular data using a Fourier transform to identify periodic oscillations characteristic of cell nuclei. The periodic oscillations can be correlated with nuclear size and thus will possess diagnostic value. Another approach to analyzing a/LCI data is to compare the data to a database of angular scattering distributions generated with finite element method (FEM) or T-Matrix calculations, as examples. Such calculations may offer superior analysis as there are not subject to the same limitations as Mie theory. For example, FEM or T-Matrix calculations can model non-spherical scatterers and scatterers with inclusions while Mie theory can only model homogenous spheres.
Therefore, it is to be understood that the description and claims are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. It is intended that the embodiments cover the modifications and variations of the embodiments provided they come within the scope of the appended claims and their equivalents. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
This patent application is related to U.S. Pat. No. 7,102,758, filed on May 6, 2003 and entitled “Fourier Domain Low-Coherence Interferometry for Light Scattering Spectroscopy Apparatus and Method,” which is incorporated herein by reference in its entirety. This patent application is also related to U.S. Pat. No. 7,595,889, filed on Oct. 11, 2006 and entitled “Systems and Methods for Endoscopic Angle-Resolved Low Coherence Interferometry,” which is incorporated herein by reference in its entirety. This patent application is also related to U.S. patent application Ser. No. 12/210,620, filed on Sep. 15, 2008 and entitled “Apparatuses, Systems, and Methods for Low-Coherence Interferometry (LCI),” which is incorporated herein by reference in its entirety. This patent application is also related to U.S. patent application Ser. No. 12/350,689, filed on Jan. 8, 2009 and entitled “Systems and Methods for Tissue Examination, Diagnostic, Monitoring, and/or Monitoring,” which is incorporated herein by reference in its entirety. This patent application is also related to U.S. patent application Ser. No. 11/780,879, filed on Jul. 20, 2007 and entitled “Protective Probe Tip, Particularly for Use on a Fiber-Optic Probe Used in an Endoscopic Application,” which is incorporated herein by reference in its entirety. This patent application is also related to U.S. Provisional Patent Application No. 61/297,588, filed on Jan. 22, 2010 and entitled “Dual Window Processing Schemes for Spectroscopic Optical Coherence Tomography (OCT) and Fourier Domain Low Coherence Interferometry,” which is incorporated herein by reference in its entirety.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US10/27972 | 3/19/2010 | WO | 00 | 2/4/2013 |