US2014288419A1PendingUtilityA1
Method and apparatus for quantitative imaging of blood perfusion in living tissue
Assignee: UNIV OREGON HEALTH & SCIENCEPriority: May 4, 2009Filed: Jun 9, 2014Published: Sep 25, 2014
Est. expiryMay 4, 2029(~2.8 yrs left)· nominal 20-yr term from priority
A61B 5/0066A61B 5/0042A61B 5/7203A61B 5/0261A61B 5/7257
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Claims
Abstract
Embodiments provide methods and systems for imaging, and, more specifically, to a method and apparatus for quantitative imaging of blood perfusion in living tissue. Some embodiments are directed to methods of obtaining quantitative imaging of blood perfusion in living tissues using Doppler optical micro-angiography (DOMAG).
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A method of quantifying blood perfusion in a living tissue sample, comprising:
obtaining an optical microangiography (OMAG) image of a sample, wherein the image has an OMAG background sample; digitally reconstructing a homogeneous ideal static background tissue; replacing the OMAG background sample with the digitally reconstructed homogeneous ideal static background tissue; correlating two or more neighboring A-lines with the digitally reconstructed homogeneous ideal static background tissue; and measuring a phase difference between the two or more neighboring A-lines to quantify blood perfusion in the sample.
2 . The method of claim 1 , wherein obtaining an OMAG image of the sample comprises:
scanning the sample with an incident beam from a light source to generate two or more neighboring A-lines; detecting one or more spectral interference signals from the sample; modulating the one or more spectral interference signals while scanning the sample in a cross-sectional direction (B scan); and obtaining at least one image of the sample from the modulated one or more spectral interference signals, the at least one image including a selected one of a full range structural image of the sample, a separated structure/flow image of the sample, and a background sample.
3 . The method of claim 1 , wherein measuring the phase difference between the two or more neighboring A-lines to quantify blood perfusion in the sample comprises using a phase resolved technique to extract flow velocity information.
4 . The method of claim 2 , wherein obtaining at least one image from the sample comprises:
separating structure information of the sample and flow information of the sample; and obtaining a first image and a second image, the first image including the structure information and the second image including the flow information.
5 . The method of claim 2 , wherein scanning comprises scanning the sample with the incident beam in x and λ directions to obtain a first two dimensional (2-D) spectral interferogram data set, said x direction including one or more columns and said λ direction including one or more rows.
6 . The method of claim 5 , wherein obtaining the at least one image comprises:
calculating discrete analytic functions, along the x-direction and row by row in the λ direction of the first 2-D data set, to obtain a complex valued function of the first 2-D data set; and converting the complex valued function of the first 2-D data set from a spectral domain to a time domain, column by column in the x direction, to obtain the at least one image of the sample.
7 . The method of claim 6 , wherein calculating discrete analytic functions comprises Hilbert-transforming the first 2-D data set.
8 . The method of claim 6 , wherein converting the complex valued function of the first 2-D data set comprises Fourier-transforming the complex valued function of the first 2-D data set.
9 . The method of claim 5 , further comprising scanning the sample with the incident beam in the x and λ directions along y direction to obtain a second 2-D spectral interferogram data set, said first and second 2-D data sets forming a three-dimensional spectral interferogram data set.
10 . The method of claim 2 , wherein said obtaining at least one image comprises obtaining the separated structure/flow image of the sample, and wherein the flow image of the sample is indicative of a direction of flow of the sample.
11 . The method of claim 1 , further comprising filtering the spectral interference signals for each B scan using a phase-only filter.
12 . The method of claim 11 , wherein filtering the spectral interference signals for each B scan using a phase-only filter comprises:
Fourier-transforming interpolated fringe data along an x direction to obtain frequency components; forcing the magnitudes of the frequency components to be unity while leaving the phases unchanged; and inverse-Fourier-transforming phase data along the x direction to obtain a filtered interferogram signal.
13 . A method for quantifying blood perfusion in a sample, comprising:
scanning a flowing sample with an incident beam from a light source; detecting one or more spectral interference signals from the flowing sample to generate an OMAG blood flow sample; digitally reconstructing a homogeneous ideal static background tissue; replacing a real background sample with the digitally reconstructed homogeneous ideal static background tissue; correlating two or more neighboring A-lines with the digitally reconstructed homogeneous ideal static background tissue; and measuring the phase difference between the two or more neighboring A-lines to quantify blood perfusion in the sample.
14 . The method of claim 13 , wherein digitally reconstructing a homogeneous ideal static background tissue comprises digitally reconstructing an ideal sample background with a constant backscattering coefficient a 0 and a refractive index n 0 throughout the sample according to the equation:
I 0 ( k j ,t )=2 S ( k j ) E R ∫ −∞ ∞ a 0 ( z,t )cos(2 k j n 0 ( z,t ) z ) dz,
wherein a 0 (z,t)≡a 0 and n 0 (z,t)≡n 0 throughout the sample.
15 . The method of claim 13 , wherein an OMAG blood flow signal is defined as:
I ′( k j ,t )=2 S ( k j ){ E R ∫a 0 cos(2 k j n 0 z ) dz+E R a ( z 1 ,t 1 )cos [2 k j n ( z 1 ,t 1 )( z 1 −vt )]}.
16 . The method of claim 15 , further comprising:
treating t (the time variable) as a constant; and performing a Fourier transformation upon k (wavelength) such that
{tilde over ( I )}( z,t )= FT −1 {I ( k j ,t )}| k =A ( z,t )exp[ i φ( z,t )]
wherein ψ(z, t) is a phase of an analytic signal.
17 . The method of claim 16 , further comprising evaluating a phase difference between neighboring A-scans, n and n−1, according to the equation:
Δ
ϕ
(
z
,
t
)
=
tan
-
1
[
Im
[
I
~
(
z
,
t
n
)
·
I
~
*
(
z
,
t
n
-
1
)
]
Re
[
I
~
(
z
,
t
n
)
·
I
~
*
(
z
,
t
n
-
1
)
]
]
.
18 . The method of claim 17 , further comprising generating a velocity of flow signal using the equation:
v
(
z
,
t
)
=
λ
Δ
ϕ
(
z
,
t
)
4
π
n
Δ
t
wherein v(z,t) is a flow velocity at depth z, wherein Δt is a time interval between neighboring A-lines, and wherein n is a refractive index of the sample.Join the waitlist — get patent alerts
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