# US 9,517,005 B2 · Attenuation-based optic neuropathy detection with three-dimensional optical coherence tomography

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- Number: US 9,517,005 B2
- Document ID: US9517005B2
- Status: Granted
- Kind: B2
- Application number: 14/825,286
- Filed: 2015-08-13
- Published: 2015-12-03
- Granted: 2016-12-13
- Earliest claimed: 2013-02-01
- Assignees: Topcon Corporation
- Applicants: Kabushiki Kaisha TOPCON
- Inventors: Charles A. Reisman
- Web page: https://patentgrep.com/patent/US9517005B2

## CPC

- A61B 3/0025: {characterised by electronic signal processing, e.g. eye models}
- A61B 3/0058: {for multiple images}
- A61B 3/102: {for optical coherence tomography [OCT]}
- A61B 3/12: for looking at the eye fundus, e.g. ophthalmoscopes (A61B3/13 takes precedence)
- A61B 3/1225: {using coherent radiation}
- A61B 3/14: Arrangements specially adapted for eye photography
- G06T 7/0012: {Biomedical image inspection}
- G06T 2207/10101: Optical tomography; Optical coherence tomography [OCT]
- G06T 2207/30041: Eye; Retina; Ophthalmic
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

Optical coherence tomography (OCT) scan data of a subject is acquired over a region of interest which can include an optic disc or a macula of a retina. Layer boundaries of retinal layers are identified in the OCT scan data to facilitate measurements. In one aspect, a measurement related to ratio value between a total backscattered signal intensity of one or more target layers of the retina and a total backscattered signal intensity of one or more reference layers is computed on a location-by-location basis within a region of interest of the OCT scan data. Measurements can be collected, aggregated, analyzed, and displayed in connection with other information taken or derived from the OCT scan data.

## Claims

### Claim 1

A method for detecting and monitoring diseases, comprising:
obtaining imaging data of a region of the retina;
identifying boundaries between layers of the retina in the region of the retina, based on the imaging data; and
determining, on a location-by-location basis for at least a portion of the region of the retina, a measurement value related to a ratio value between a total backscattered signal intensity of one or more target layers of the retina and a total backscattered signal intensity of one or more reference layers to generate a set of measurement values for locations in the portion of the region of the retina,
wherein the measurement value is generally monotonic with respect to an integrated attenuation value such that the ratio value is used as a proxy measurement for the integrated attenuation value.

### Claim 2 (depends on 1)

The method of claim 1, wherein the integrated attenuation value is determined according to the following relation:
μ
ATT
⁢
d
=
log
⁡
(
R
/
β
+
1
)
2
,
where
β is modeled as a substantially constant value,
R is the ratio value, and
μATTd represents a total attenuation of light over a depth d of the retina.

### Claim 3 (depends on 1)

The method of claim 1, wherein the set of measurement values are a set of integrated attenuation values calculated location-by-location.

### Claim 4 (depends on 2)

The method of claim 2, further comprising:
standardizing a depth over which the total backscattered signal intensity of the one or more reference layers is determined from location to location,
wherein the standardizing facilitates maintaining β as a substantially constant value.

### Claim 5 (depends on 4)

The method of claim 4, wherein the ratio value R for a particular location, with standardization of the depth over which the total backscattered signal intensity of the one or more reference layers, is given by:
R
=
T
IRL
T
ref
≈
∑
z
=
1
d
IRL
⁢
T
IRL
⁡
(
z
)
1
d
ref
⁢
∑
z
=
1
d
ref
⁢
T
ref
⁡
(
z
)
,
where
TIRL(z) is a signal intensity of a backscattered signal from the one or more target layers at depth z,
Tref(z) is a signal intensity of a backscattered signal from the one or more reference layers at depth z,
dIRL is a thickness of the one or more target layers, and
dref is a thickness of the one or more reference layers.

### Claim 6 (depends on 1)

The method of claim 1, wherein the one or more target layers include a retinal nerve fiber layer, a ganglion cell layer, an inner plexiform layer, or combinations thereof.

### Claim 7 (depends on 1)

The method of claim 1, wherein the one or more reference layers include a retinal pigment epithelium.

### Claim 8 (depends on 1)

The method of claim 1, wherein the region of the retina includes at least one of an optic disc or a macula of the retina.

### Claim 9 (depends on 1)

The method of claim 1, wherein the imaging data comprises optical coherence tomography (OCT) scan data.

### Claim 10 (depends on 1)

The method of claim 1, wherein the imaging data is three-dimensional or is obtained using a circumpapillary scan.

### Claim 11 (depends on 1)

The method of claim 1, further comprising displaying information derived from at least one of the set of measurement values or the imaging data.

### Claim 12 (depends on 11)

The method of claim 11, wherein displaying the information comprises displaying a visual representation of the set of measurement values as an overlay on image generated from the imaging data.

### Claim 13 (depends on 1)

The method of claim 1, further comprising:
respectively comparing measurement values from the set of measurement values to one or more thresholds; and
calculating a probability of a disease based on comparison results.

### Claim 14 (depends on 13)

The method of claim 13, wherein the one or more thresholds are pre-determined from a normative database.

### Claim 15 (depends on 13)

The method of claim 13, wherein the one or more thresholds vary by location.

### Claim 16

A method for detecting and monitoring diseases, comprising:
determining, on a location-by-location basis for at least a portion of a region of a retina, a measurement value related to a ratio value between a total backscattered signal intensity of one or more target layers of the retina and a total backscattered signal intensity of one or more reference layers to generate a set of measurement values for locations in the portion of the region of the retina;
calculating a probability of a disease based on the measurement values.

### Claim 17 (depends on 16)

The method of claim 16, further comprising
acquiring imaging data for the region of interest of the retina; and
segmenting the imaging data to identify layer boundaries between layers of the retina,
wherein the measurement values are determined based on the segmented imaging data.

### Claim 18 (depends on 17)

The method of claim 17, wherein the imaging data is optical coherence tomography (OCT) scan data.

### Claim 19 (depends on 17)

The method of claim 17, wherein the imaging data is three-dimensional or is obtained using a circumpapillary scan.

### Claim 20 (depends on 16)

The method of claim 16, wherein the measurement value is generally monotonic with respect to an integrated attenuation value such that the ratio value is used as a proxy measurement for the integrated attenuation value.

### Claim 21 (depends on 20)

The method of claim 20, wherein the integrated attenuation value is determined according to the following relation:
μ
ATT
⁢
d
=
log
⁡
(
R
/
β
+
1
)
2
,
where
β is modeled as a substantially constant value,
R is the ratio value, and
μATTd represents a total attenuation of light over a depth d of the retina.

### Claim 22 (depends on 21)

The method of claim 21, further comprising:
standardizing a depth over which the total backscattered signal intensity of the one or more reference layers is determined from location to location,
wherein the standardizing facilitates maintaining β as a substantially constant value.

### Claim 23 (depends on 16)

The method of claim 16, further comprising:
respectively comparing measurement values from the set of measurement values to one or more thresholds, wherein calculating a probability of a disease is based on results of comparing the measurement values to the one or more thresholds.

### Claim 24 (depends on 23)

The method of claim 23, wherein the one or more thresholds vary by location.

### Claim 25 (depends on 23)

The method of claim 23, wherein the one or more thresholds are based on normative data, the normative data being calculated by:
collecting a plurality of imaging data from a plurality of confirmed normal subjects,
aggregating measurements from the plurality of imaging data, and
statistically compiling aggregated measurements.

### Claim 26 (depends on 23)

The method of claim 23, further comprising displaying a representation of the probability of the disease.

### Claim 27 (depends on 22)

The method of claim 22, wherein the ratio value for a particular location, with standardization of the depth over which the total backscattered signal intensity of the one or more reference layers, is given by:
R
=
T
IRL
T
ref
≈
∑
z
=
1
d
IRL
⁢
T
IRL
⁡
(
z
)
1
d
ref
⁢
∑
z
=
1
d
ref
⁢
T
ref
⁡
(
z
)
,
where
TIRL(z) is a signal intensity of a backscattered signal from the one or more target layers at depth z,
Tref(z) is a signal intensity of a backscattered signal from the one or more reference layers at depth z,
dIRL is a thickness of the one or more target layers, and
dref is a thickness of the one or more reference layers.

### Claim 28 (depends on 16)

The method of claim 16, wherein the one or more target layers include a retinal nerve fiber layer, a ganglion cell layer, an inner plexiform layer, or combinations thereof.

### Claim 29 (depends on 16)

The method of claim 16, wherein the one or more reference layers include a retinal pigment epithelium.

### Claim 30 (depends on 16)

The method of claim 16, wherein the region of the retina includes at least one of an optic disc or a macula of the retina.

### Claim 31 (depends on 16)

The method of claim 16, further comprising displaying information derived from at least one of the set of measurement values.