WO2013106760A1

WO2013106760A1 - Systems, methods and computer-readable medium for determining depth-resolved physical and/or optical properties of scattering media by analyzing measured data over a range of depths

Info

Publication number: WO2013106760A1
Application number: PCT/US2013/021299
Authority: WO
Inventors: Koenraad Arndt VERMEER
Original assignee: The General Hospital Corporation
Priority date: 2012-01-12
Filing date: 2013-01-11
Publication date: 2013-07-18

Abstract

According to exemplary embodiments of the present disclosure, method, system and computer-accessible medium can be provided for determining at least one property of at least one biological structure. For example, it is possible to obtain a plurality of signals received at particular depths within the biological structure(s), where at least first one of the signals can be obtained from a first depth of the particular depths, and at least second one of the signals can be obtained from a second depth of the particular depths. The first and second depths can be different from one another. In addition, it is possible to determine information based on the signals and an assumed property of the biological structure(s). Further, it is possible to determine at least one calculated property based on the information by excluding at least a portion of the information associated with the signals provided from the particular depths that are closer than a predetermined depth within the biological structure(s). For example, the calculated property can be an attenuation optical property and/or a physical property.

Description

SYSTEMS, METHODS AND COMPUTER-READABLE MEDIUM FOR DETERMINING DEPTH-RESOLVED PHYSICAL AND/OR OPTICAL PROPERTIES OF SCATTERING MEDIA BY ANALYZING MEASURED DATA

OVER A RANGE OF DEPTHS CROSS-REFERENCE TO RELATED APPLIC ATION(S

[0001] This application is based upon and claims the benefit of priority from U.S. Patent Application Serial No. 61/585,916 filed on January 12, 2012, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to a determination of physical and/or optical information regarding a sample, and more particularly to exemplary embodiments of systems, methods and computer-readable medium for determining depth-resolved physical or optical properties of scattering media by analyzing measured data over a range of depths.

BACKGROUND INFORMATION

[0003] Several techniques are used for depth-resolved imaging of scattering media, such as confocal microscopy and/or optical coherence tomography (OCT). In these techniques, incident light travels through the media, interacts with the media (e.g., an anatomical sample), and is collected by one or more detectors. The interaction of the light and the media can be complex, because interaction does not only take place at a single depth. Instead, the incident bundle generally interacts with many and/or all layers it passes through, scatters at some depth and the scattered beam again interacts with the media until it arrives at the detector.

[0004] Because the measurements are the result of this complex interaction, the signal strength corresponding to a single depth measurement does not directly represent a physical or optical property of the medium at that depth. Therefore, commonly only morphological features of the measurements, often visualized in an image, are evaluated. However, these morphological features also depend on the signal strength and are therefore not always clearly defined in OCT images.

[0ΘΘ5] According to an exemplary embodiment of the present disclosure, it is possible to determine physical and/or optical properties of the medium from the measurements. For this determination, information of other, deeper locations can be included in the reconstruction process. An example of such a reconstruction is the determination of attenuation coefficients

. l - from OCT data. In this case, OCT data from both nearer and deeper locations are used to determine, iteratively, the local scattering intensity and the local attenuation coefficient.

[0006] For example, with OCT techniques, the sample is probed by a coherent light source and the depth-resolved backscatter signal intensity is recorded. The exemplary OCT techniques can be implemented in many ways, with fixed or moving reference mirrors, with spectrometers or swept-source systems, etc. In such cases, however, the OCT signal is generally dependent on energy of the backscattered beam that reaches the detector. Many of these measurements along a line are then combined to produce an image, as shown in Figure 1 . [0007] In an exemplary OCT image, the intensity that is measured from a certain depth can be gray scale coded, where white can indicate a strong signal, and black - a weak or no signal. The OCT beam is generally incident from above on the tissue. Unfortunately, these images likely do not reflect the physical or optical properties of the tissue. Instead, they only illustrate the result of the complex interaction, which can mean that the same tissue may appear differently (i.e., with different signal intensity, illustrated by the different signal intensity of the RPE at the locations indicated by arrows 20 in Figure 1) at different locations, determined by how the surrounding tissue is structured. This is because the exemplary OCT signal depends not only on the optical properties of the media at some depth, which result in the backscattered signal. Instead, the exemplary OCT signal is also dependent on the strength of the incident beam at that location, which is affected by the media it passes through first. In addition, the resulting backscattered beam again has to pass through some part of the media before it reaches the detector and is therefore further attenuated. This can result in artifacts that are frequently observed in OCT images. One example is the shading of blood vessels. Because the blood vessels cause a large reduction of the intensity of the incident light beam, the scatter intensity at deeper locations is largely reduced and is further attenuated on the way back to the detector. This can result in apparent gaps of underlying tissue, which clearly does not mimic the tissues structure (see figure 1 , arrows 10). Another artifact is the very dim appearance of the choroid and sclera, both scattering tissue types, due to the attenuation of the incident light beam in other highly scattering layers, especially the retinal nerve fiber layer (RNFL) and the retinal pigment epithelium (RPE). Yet another artifact is the reduced intensity in the image in case of floaters or media opacities (e.g. in the cornea, the lens or the vitreous), which attenuates the power of the incident beam. [0008] Accordingly, there is a need to address at least some of the deficiencies described herein above.

SUMMARY OF EXEMPLARY EMBODIMENTS

[0009] At least some of such deficiencies can be address with exemplary embodiments of the present disclosure providing systems, methods and computer-readable medium for determining depth-resolved physical or optical properties of scattering media by analyzing measured data over a range of depths.

[0010] The exemplary systems, methods and computer-accessible medium can analyze the imaging process, thereby modeling the process of the interaction between the incident light beam and the tissue, resulting in the OCT measurements. Subsequently, the inverse problem can be solved to produce, for example, local attenuation coefficients from the OCT data. The resulting image can represents a physical and/or optical property of the local media that can be free of some or many of the artifacts in the original OCT data set. Because the exemplary image shows tissue properties rather than the result of complex interactions, the signal strength of the tissue can be largely independent of the structure of surrounding tissue layers. The resulting exemplary image can therefore be better suited for image processing, likely resulting, for example, in a segmentation of tissue layers. In addition, these physical or optical tissue properties can be useful for diagnosis and monitoring of disease and/or disease progression. [0011] For example, an in depth-resolved imaging of scattering media, incident light interacts with tissue in a complex way before the signal reaches the detector. Indeed, light/radiation can interact with media between the light source and a specific depth, then scatters at that depth and the backscattered light again interacts with media on its way to the detector. The resulting depth-resolved signal therefore likely does not directly represent a physical or optical property of the media at. those depths.

[0012] According to an exemplary embodiment of the present disclosure, systems, methods and computer-accessible medium can be provided to determine physical or optical properties based on such a depth-resolved signal. For example, almost all the light can interact with the media, and that the energy of the incident light at a certain depth is likely therefore related to the integral of the scattered light from all deeper locations. Based on the detected signals, the properties of the media can be estimated in an iterative way. The exemplary system, method and computer-accessible medium can be used together with, e.g., retinal optical coherence tomography data, facilitating the calculation of depth-resolved attenuation coefficients. It is possible to, e.g., transform data resulting from complex interactions of light and media at a range of depths into data representing a decoupled physical or optical property of the tissue at a range of depths.

[0013] According to certain exemplary embodiments of the present disclosure, systems, methods and computer-accessible medium can be provided for determining at least one property of at least one biological structure. For example, with such exemplary systems, methods and computer-accessible medium, it is possible to obtain a plurality of signals received at particular depths within the biological structure(s). At least first one of the signals can be obtained from a first depth of the particular depths, and at least second one of the signals can be obtained from a second depth of the particular depths. The first and second depths can be different from one another. In addition, it is possible to determine information based on the signals and an assumed property of the biological structure(s). Further, at least one calculated property can be calculated based on the information by excluding at least a portion of the information associated with the signals provided from the particular depths that are closer than a predetermined depth within the biological structure(s), where the calculated property can be an attenuation optical property and/or a physical property. [0014] According to one exemplary embodiment of the present disclosure, the determinations of the information and the calculated property can be reiterated at least once, such that, when the information is determined, the assumed property can be replaced with the calculated property of the determination of the calculated property to obtain the property of the biological structure(s). The signals can be optical coherence tomography signals or ultrasound signals. The calculated property can includes local optical properties of scattering media of the biological structure(s), and the local optical properties can be determined using the information from a range of the particular depths. For example, the local optical properties can be determined using the information obtained from the depth which is a shallower depth and the information obtained at the second depth which is a larger depth. It is also possible to sum the information obtained from the second depth to obtain an estimate of an intensity of a radiation forwarded to the biological structure(s). [0015] For example, the local optical property can include an attenuation coefficient. The calculated property can include at least one optical property or at least one physical property which are iteratively determined from the information to be estimate at various depths within the structure(s). The calculated property can be used for diagnosis or for at least one of a manual segmentation or an automatic segmentation. Further, the calculated property can include a calculated attenuation, and the assumed property can be an assumed attenuation.

[0016] According to another exemplary embodiment of the present disclosure, the information can be based on a local backscattered energy from the at least one structure. The local backscattered energy can be measured by an optical coherence tomography procedure. [0017] These and other objects, features and advantages of the present disclosure will become apparent upon reading the following detailed description of exemplary embodiments of the present disclosure, when taken in conjunction with the appended drawings and claims provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further objects, features and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings showing illustrative embodiments of the present invention, in which:

[0019] Figure 1 is an exemplary OCT scan of a healthy eye;

[0020] Figure 2 is an exemplary attenuation coefficient image produced by processing the OCT image according to exemplary embodiments of the present disclosure;

[0021] Figure 3 is a flow diagram of a method according to an exemplary embodiment of the present disclosure; and

[0022] Figure 4 is a diagram of a system according to an exemplary embodiment of the present disclosure. [0023] Throughout the drawings, the same reference numerals and characters, if any and unless otherwise stated, are used to denote like features, elements, components, or portions of the illustrated embodiments. Moreover, while the subject disclosure will now be described in detail with reference to the drawings, it is done so in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described exemplary embodiments without departing from the true scope and spirit of the subject disclosure and appended claims provided herewith.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Exemplary Procedure

[0024] The presented method models the interaction of light with the medium and the resulting signal at the detector and then solves the inverse problem iteratively to locally calculate the physical or optical properties of the medium.

Exemplary Model

Exemplary Attenuation of incoming beam

[0025] During an exemplary propagation thereof through a locally homogeneous layer, the power of the incoming beam is attenuated according to: dL(x) = -^(x)L(x)dx , ( 1 ) where L(x) is the power of the beam at depth x and μ is the attenuation coefficient of the layer. Solving this, with boundary condition L(0) - L₀ to define the power of the incoming beam, results in the following equation for the attenuated beam:

L(x) = L₀e " (2) which, for a constant attenuation coefficient, reduces to L(x) = L₀e ^{' JX} . An exemplary calculation of the power of the beam L(x) at location x in equation 2 provides that the attenuation coefficients up to position x are known, and that the power of the incident beam L_Q is known.

Exemplary local incident light power and integration

[0026] Another way to define the power of the incoming beam is by analyzing the attenuated power A(x) dA(x) = -dL(x) -~ μ(χ)∑(χ)άχ . (3) integrating this equation and using the fact that all power can eventually be attenuated by the medium results in A(x) ^ f ,u(x) L(x)dx ^ f u(x)L(x)dx - J ju(x)L(x)dx = L₀ - \ μί_.χ) L(x)dx . (4)

0 0 >: x

The (remaining) power of the incoming beam can be defined by

L{x) - L₀ - A{x)^■■- j μ(χ)∑(χ)άχ . (5)

[0027] In contrast to Equation 2, this exemplary formulation of L(x) does not require that L₀ is known. What should be known is the attenuation coefficient at location x and deeper, and the intensity L(x) at location x and deeper.

Relating exemplary attenuation and backscatter

[0028] An exemplary attenuation can result from both scattering and absorption. If a fixed fraction a of the attenuated light is backscattered, the energy density of the backscattered light at depth x can be given by dA

B(x) = a— - a^(x)L(x) . (6)

dx

Exemplary OCT signal

[0029] Such exemplary backscattered may not be the signal that is actually measured by the exemplary OCT system and/or procedure. Instead, the signal can again be attenuated by the tissue on the way back to the tissue surface before reaching the detector, where S(x) describes the intensity of light that scattered at depth x and subsequently reaches the tissue surface:

S(x) = B(x)e ⁰ (7) where /(x) is the light intensity, that after detection by a detector and multiplied by a conversion factor β , provided the exemplary measured digital signal,

I{x) = pS{x) im{x)e " ₍₈₎

Exemplary determination of μ

[0030] To calculate μ(χ) , we write, using Equation 5, _{/( v)} _ M(x)L(x) ₌ j (x) (x) αμ(χ)Ι,{χ) ^

L(x) r ^ci-

I μ(χ)∑(χ)άχ J αμ{χ)ί(χ)άχ

Substituting Equation 6 and includin β in both the numerator and the denominator yields

[0031] Because the penetration of light in the tissue is limited to e.g., the image depth D , the calculation of μ(χ) is approximated by

J^" βΒ(χ)άχ

Exemplary iterative procedure

[0032] Although the exemplary analysis may not provide a way to directly calculate μ(χ) from the OCT image data I{x) , according to exemplary embodiments of the present disclosure can calculate/determine the backscattered signal from the image data and from μ(χ) , and determine such μ(χ) from the backscattered signal. Given that both μ(χ) and βΒ{χ) are unknown, it is unlikely to directly calculate the attenuation coefficients. Instead, an exemplary numerical procedure can be implemented to estimate both quantities.

[0033] One exemplary procedure to perform such estimation can include a calculation of μ(χ) from the OCT image data l(x) by, e.g., an iterative routine, an exemplary embodiment of which is shown in a flow diagram of Figure 3. In this exemplary procedure illustrated in Figure 3, the attenuation coefficients μ(χ) can be initialized by a small value. Based on these initial values and the image data I(x) , βΒ(χ) can be calculated by Equation 8. Then, based on the calculated βΒ(χ) , μ(χ) can be calculated by Equation 1 1. This exemplary procedure is repeated until it converges. This exemplary procedure can be further described, with reference to Figure 3, as follows;

1. Initialize μ⁽⁰⁾(χ) to a small number (block 310) and set k to 0 (block 320).

2. k < k ^■ \ (block 330} 3. Calculate pB^(k) (x) from μ^{(Ιί Λ)} (χ) and I(x) (Equation 8) (block 340).

4. Calculate / *> (*) from βΒ^(Ι,) (χ) (Equation 1 1) (block 350).

5. Determine if a convergence occurred (block 360), and if not, repeat procedures 2-5 (blocks 330-360) until the convergence is reached.

6. Determine μ(χ) - μ^(Ιί) (χ) (block 370)

[0034] The exemplary local attenuation μ χ) can be given by μ^{Ι<) (χ) . The exemplary convergence can be defined in various ways. For example, a fixed number of iterations can be used. Alternatively, the size of the update step can be analyzed, and convergence can be assumed when it is below some absolute or relative value.

Exemplary Discretization

[0035] An exemplary mathematical formulation indicated herein can be usable in the continuous case. However, certain real-life measurements can be discrete, and therefore an exemplary discrete set of equations should be derived. Various exemplary discretizations can be used, each based on different assumptions. One such exemplary discretization is described as follows.

[0036] For example, constant measurement intervals, centered on the sample points and with a constant spacing of can be assumed. The discrete version of I(x) , /[/] , can then be defined as I{x) - /[/] , where x = (i + ±)A_X . (12)

[0037] Similarly, the discrete version of μ(χ) can be defined. For example, replacing the integral of Equation 8 by its discrete version by assuming constant μ(χ) over the pixel size can result in

and solving for ¾?[/] yields βΒ[ί] = Ι[ ^; \ (14)

[0038] Similarly, the exemplary calculation of the discrete attenuation coefficient μ[ί] can be given by . , , »1 - (, 5) Further exemplary, description

[0039] According to further exemplary embodiments of the present disclosure, the system, method and computer-accessible medium can be further modified including additional effects. For example, in OCT procedures and systems, the limited coherence length can result in a reduced signal tor depths at an increasing distance from the so-called zero-delay line (which can be determined by the position of the static mirror). This signal fall-off can be modeled by an exponential function and/or another decay function, and included in the exemplary procedure and/or system. The limited depth-of-focus can be modeled in a similar way, where the exact focus parameters are taken into account to correct for the collection efficiency of the light over the axial position in the focus. Another exemplary modification of the exemplary system, method and computer-accessible medium according to the present disclosure can include the treatment of noise. For example, a small value, which can be based on shot-noise calculations or on a reference measurement describing the system noise, can be subtracted from the OCT data to reduce the accumulation of noise in regions with little scattering signal. Using multiple scattered lights can also result in a background signal. This contribution can be modeled and accounted for by subtraction according to the exemplary embodiments of the present disclosure. Data of neighboring pixels can be combined to get a better estimate of the local scattering signal. Various regularization methods known to those having ordinary skill in the art can be used on the estimation of both βΒ(χ) and μ(χ) , thereby incorporating prior knowledge about the structure of the tissues.

[0040] An exemplary initialization of μ(χ) can be performed in several ways. According to one exemplary procedure, the initialization can be done by initializing μ(χ) with a small number for every x . This exemplary small number can be chosen such that the total attenuation over the image depth D is large, for example, 99.9%. For constant μ(χ) ,

Equation 2 can reduce to L(x) = L₀e^~,c< . Evaluating this equation at x = D and rearranging the equation results in /. = -— log— . Setting the ratio —™ to 0.001 to match the

D L₀

99.9% attenuation then results in the initial value for μ . [0041 ] In other cases, a prior knowledge about the expected values for μ{χ) may already be available, for example, as being obtained from mean values of a large data set. Using such further estimates to initialize μ{χ) can result in a faster convergence of the exemplary procedure.

Further Example

[0042] While the systems, methods and computer accessible medium according to exemplary embodiments of the present disclosure can be more generally applicable, attention is drawn to an example shown in Figure 1 illustrating exemplary retinal OCT images of healthy human eyes.

[0043] In particular, the exemplary image in Figure 1 was generated using an OCT scan of a healthy eye. As shown in Figure 1 , blood vessels can cause severe shading of underlying tissue (see darker arrows) and layers of tissue that are presumably homogeneous show varying brightness (RPE, see lighter arrows). [0044] For example, processing the exemplary data from Figure 1 using the systems, methods and computer accessible medium according to exemplary embodiments of the present disclosure can result in an attenuation coefficient image, as shown in Figure 2.

[0045] In particular, Figure 2 illustrates an exemplary attenuation coefficient image produced by processing the exemplary OCT image using the systems and/or method according to exemplary embodiments of the present disclosure. For example, as shown in the exemplary image of Figure 2, blood vessels result in almost no shading, the RPE is shown as a uniformly bright layer, the choroid and sclera are depicted as realistically highly attenuating tissues and the pixel brightness has a physical meaning (see grey scale bar).

[0046] The shadowing due to blood vessels can be largely removed and the RPE has a more uniform appearance. Figure 2 also further illustrates the scattering properties of the choroid and the sclera. The noisy appearance can be due to the small amount of incident light remaining after passing through the retinal layers.

Exemplary System

[0047] Figure 4 shows an exemplary diagram of an exemplary embodiment of a system according to the present disclosure. For example, exemplary procedures in accordance with the present disclosure described herein can be performed by a processing arrangement and/or a computing arrangement 102. Such processing/computing arrangement 102 can be, e.g., entirely or a part of, or include, but not limited to, a computer/processor 104 that can include, e.g., one or more microprocessors, and use instructions stored on a computer-accessible medium (e.g., RAM, ROM, hard drive, or other storage device). [0048] As shown in Figure 4, e.g., a computer-accessible medium 106 (e.g., as described herein above, a storage device such as a hard disk, floppy disk, memory stick, CD-ROM, RAM, ROM, etc., or a collection thereof) can be provided (e.g., in communication with the processing arrangement 102). The computer-accessible medium 106 can contain executable instructions 108 thereon. In addition or alternatively, a storage arrangement 1 10 can be provided separately from the computer-accessible medium 106, which can provide the instructions to the processing arrangement 102 so as to configure the processing arrangement to execute certain exemplary procedures, processes and methods, as described herein above, for example. [0049] Further, the exemplary processing arrangement 102 can be provided with or include an input/output arrangement 1 14, which can include, e.g., a wired network, a wireless network, the internet, an intranet, a data collection probe, at least one sensor, etc. The input/output arrangement can receive information/data from an OCT system 150 to provide information to the processing arrangement 102. Using such information received from the OCT system 150, the exemplary processing arrangement 102 can be configured to execute instructions to determine depth-resolved physical or optical properties of scattering media by analyzing measured data over a range of depths As shown in Figure 4, the exemplary processing arrangement 102 can be in communication with an exemplary display arrangement 1 12, which, according to certain exemplary embodiments of the present disclosure, can be a touch-screen configured for inputting information to the processing arrangement in addition to outputting information from the processing arrangement, for example. Further, the exemplary display 1 12 and/or a storage arrangement 1 10 can be used to display and/or store data in a user-accessible format and/or user-readable format.

[0050] The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. Indeed, the arrangements, systems and methods according to the exemplary embodiments of the present disclosure can be used with and/or implement any OCT system, OFDI system, SD-OCT system or other imaging systems, and for example with those described in International Patent Application PCT/US2004/029148, filed September 8, 2004 which published as International Patent Publication No. WO 2005/047813 on May 26, 2005, U.S. Patent Application No. 1 1/266,779, filed November 2, 2005 which published as U.S. Patent Publication No. 2006/0093276 on May 4, 2006, and U.S. Patent Application No. 10/501 ,276, filed July 9, 2004 which published as U.S. Patent Publication No. 2005/0018201 on January 27, 2005, and U.S. Patent Publication No. 2002/0122246, published on May 9, 2002, the disclosures of which are incorporated by reference herein in their entireties. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures which, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. In addition, all publications and references referred to above can be incorporated herein by reference in their entireties. It should be understood that the exemplary procedures described herein can be stored on any computer accessible medium, including a hard drive, RAM, ROM, removable disks, CD-ROM, memory sticks, etc., and executed by a processing arrangement and/or computing arrangement which can be and/or include a hardware processors, microprocessor, mini, macro, mainframe, etc., including a plurality and/or combination thereof. In addition, certain terms used in the present disclosure, including the specification, drawings and claims thereof, can be used synonymously in certain instances, including, but not limited to, e.g., data and information. It should be understood that, while these words, and/or other words that can be synonymous to one another, can be used synonymously herein, that there can be instances when such words can be intended to not be used synonymously. Further, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it can be explicitly being incorporated herein in its entirety. All publications referenced above can be incorporated herein by reference in their entireties.

Claims

WHAT IS CLAIMED IS:

1. A method for determining at least one property of at least one biological structure, comprising:

(a) obtaining a plurality of signals received at particular depths within the at least one biological structure, wherein at least first one of the signals is obtained from a first depth of the particular depths, and at least second one of the signals is obtained from a second depth of the particular depths, the first and second depths being different from one another;

(b) determining information based on the signals and an assumed property of the at least one biological structure; and

(c) determining at least one calculated property based on the information by excluding at least a portion of the information associated with the signals provided from the particular depths that are closer than a predetermined depth within the at least one biological structure, wherein the calculated property is at least one of an optical property or a physical property.

2. The method according to claim 1, further comprising:

(d) repeating procedures (b) and (c) at least once, such that, in procedure (b), the assumed property is replaced with the calculated property of procedure (c) to obtain the at least one property of the at least one biological structure.

3. The method according to claim 1 , wherein the signals are optical coherence tomography signals or ultrasound signals.

4. The method according to claim 1 , wherein the at least one calculated property includes local optical properties of scattering media of the at least one biological structure, and wherein the local optical properties are determined using the information from a range of the particular depths.

5. The method according to claim 4, wherein the local optical properties are determined using the information obtained from the depth which is a shallower depth and the information obtained at the second depth which is a larger depth.

6. The method according to claim 5, further comprising summing the information obtained from the second depth to obtain an estimate of an intensity of a radiation forwarded to the at least one structure.

7. The method according to claim 1 , wherein the information is a local backscattered energy from the at least one structure.

8. The method according to claim 7, wherein the local backscattered energy is measured by an optical coherence tomography procedure.

9. The method according to claim 4, wherein the local optical property includes an attenuation coefficient.

10. The method according to claim 4, wherein the at least one calculated property includes at least one optical property or at least one physical property which are iteratively determined from the information to be estimate at various depths within the at least one structure,

1 1. The method according to claim 4, wherein the at least one calculated property is used for diagnosis or for at least one of a manual segmentation or an automatic segmentation.

12. The method according to claim 1, wherein the at least one calculated property includes a calculated attenuation.

13. The method according to claim 1 , wherein the assumed property is an assumed attenuation.

14. A system for determining at least one property of at least one biological structure, comprising:

at least one first arrangement which is configured to obtain a plurality of signals received at particular depths within the at least one biological structure, wherein at least first one of the signals is obtained from a first depth of the particular depths, and at least second one of the signals is obtained from a second depth of the particular depths, the first and second depths being different from one another; and

at least one second computing arrangement which is configured to determine:

a) information based on the signals and an assumed property of the at least one biological structure; and

b) at least one calculated property based on the information by excluding at least a portion of the information associated with the signals provided from the particular depths that are closer than a predetermined depth within the at least one biological structure, wherein the at least one calculated property is at least one of an optical property or a physical property.

15. The system according to claim 14, wherein the at least one second computing arrangement is further configured to repeat procedures (a) and (b) at least once, such that, in procedure (a), the assumed property is replaced with the calculated property of procedure (b) to obtain the at least one property of the at least one biological structure.

16. The system according to claim 14, wherein the signals are optical coherence tomography signals or ultrasound signals,

17. The system according to claim 14, wherein the at least one calculated property includes local optical properties of scattering media of the at least one biological structure, and wherein the local optical properties are determined using the information from a range of the particular depths.

18. The system according to claim 17, wherein the local optical properties are determined using the information obtained from the depth which is a shallower depth and the information obtained at the second depth which is a larger depth.

19. The system according to claim 18, further comprising summing the information obtained from the second depth to obtain an estimate of an intensity of a radiation forwarded to the at least one structure.

20. The system according to claim 14, wherein the information is a local backscattered energy from the at least one structure.

21. The system according to claim 20, wherein the local backscattered energy is measured by an optical coherence tomography procedure.

22. The system according to claim 17, wherein the local optical property includes an attenuation coefficient.

23. The method according to claim 17, wherein the at least one calculated property includes at least one optical property or at least one physical property which are iteratively determined from the information to be estimate at various depths within the at least one structure.

24. The system according to claim 17, wherein the at least one calculated property is used for diagnosis or for at least one of a manual segmentation or an automatic segmentation.

25. The system according to claim 14, wherein the at least one calculated property includes a calculated attenuation.

26. The system according to claim 14, wherein the assumed property is an assumed attenuation.

27. A non-transitory computer accessible medium which includes software thereon for determining at least one property of at least one biological structure, wherein, when a computing arrangement executes the software, the computing arrangement is configured to perform procedures comprising:

(a) cause a plurality of signals received at particular depths within the at least one biological structure to be received, wherein at least first one of the signals is obtained from a first depth of the particular depths, and at least second one of the signals is obtained from a second depth of the particular depths, the first and second depths being different from one another; (b) determine information based on the signals and an assumed property of the at least one biological structure; and

(c) determine at least one calculated property based on the information by excluding at least a portion of the information associated with the signals provided from the particular depths that are closer than a predetermined depth within the at least one biological structure, wherein the calculated property is at least one of an optical property or a physical property.