# US 12,593,986 B2 · Transmission mode-photoacoustic tomography of the human brain through an acoustic window

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- Number: US 12,593,986 B2
- Document ID: US12593986B2
- Status: Granted
- Kind: B2
- Application number: 18/633,290
- Filed: 2024-04-11
- Published: 2024-10-17
- Granted: 2026-04-07
- Earliest claimed: 2023-04-12
- Assignees: California Institute of Technology
- Applicants: California Institute of Technology
- Inventors: Yang Zhang; Sri Sai Narasimha KS Dhara Venkata; Lihong Wang
- Web page: https://patentgrep.com/patent/US12593986B2

## CPC

- A61B 5/0095: {by applying light and detecting acoustic waves, i.e. photoacoustic measurements}
- A61B 5/0035: {adapted for acquisition of images from more than one imaging mode, e.g. combining MRI and optical tomography}
- A61B 5/0042: {for the brain}
- A61B 5/0073: {by tomography, i.e. reconstruction of 3D images from 2D projections (A61B5/0066 takes precedence)}
- A61B 5/4064: {Evaluating the brain (for intracranial pressure A61B5/031; for cerebral blood gases A61B5/14553; using EEG A61B5/369)}
- A61B 5/6814: {Head}
- A61B 5/6835: {Supports or holders, e.g., articulated arms}
- G01N 21/1702: {with opto-acoustic detection, e.g. for gases or analysing solids}
- A61B 2560/0462: Apparatus with built-in sensors
- A61B 2562/0233: Special features of optical sensors or probes classified in A61B5/00
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Photoacoustic imaging techniques that deliver diffuse light in transmission mode to the brain and detect acoustic waves transmitted through an acoustic window in the skull.

## Claims

### Claim 1

A photoacoustic imaging method, comprising:
delivering diffuse light in transmission mode through a skull to one side of a region being imaged in a brain;
using an ultrasonic transducer device to detect photoacoustic waves transmitted from an opposing side of the region, the photoacoustic waves received by the ultrasonic transducer device through an acoustic window in the skull, the photoacoustic waves generated based on the diffuse light delivered to the region; and
reconstructing a plurality of photoacoustic images of the region based on the photoacoustic waves detected.

### Claim 2 (depends on 1)

The photoacoustic imaging method of claim 1, wherein the photoacoustic images are reconstructed using universal back projection.

### Claim 3 (depends on 1)

The photoacoustic imaging method of claim 1, wherein the diffuse light has a central axis that intersects the acoustic window.

### Claim 4 (depends on 1)

The photoacoustic imaging method of claim 1, wherein the acoustic window is part of (i) a temporal region, (ii) a hemicraniectomy region, (iii) a fontanelle, (iv) a submandibular region, (v) a transorbital region, (vi) or a suboccipital region of the skull.

### Claim 5 (depends on 1)

The photoacoustic imaging method of claim 1, further comprising constructing a three-dimensional volumetric image from the plurality of photoacoustic images.

### Claim 6 (depends on 1)

The photoacoustic imaging method of claim 1, wherein the region being imaged is at least part of the cerebral cortex of the brain.

### Claim 7 (depends on 1)

The photoacoustic imaging method of claim 1, wherein the photoacoustic images are taken over time.

### Claim 8 (depends on 7)

The photoacoustic imaging method of claim 7, further comprising imaging a brain function based on the photoacoustic images taken over time.

### Claim 9 (depends on 7)

The photoacoustic imaging method of claim 7, further comprising using a photon recycling element to receive light reflected from the skull and reflect the light received to the skull.

### Claim 10 (depends on 7)

The photoacoustic imaging method of claim 7, further comprising using an angular scan mechanism to rotate the ultrasonic transducer device such that the plurality of photoacoustic images comprises two-dimensional images taken at different planes of rotation.

### Claim 11

A photoacoustic imaging method, comprising:
obtaining photoacoustic data recorded by one or more data acquisition devices, wherein the photoacoustic data is based on photoacoustic signals of photoacoustic waves detected by an ultrasonic transducer device, the photoacoustic waves received through an acoustic window in a skull by the ultrasonic transducer device, the photoacoustic waves based on light delivered to a region being imaged in a brain, the light delivered to the brain in transmission mode through the skull to one side of the region in the brain, and the photoacoustic waves transmitted from an opposing side of the region; and
reconstructing a plurality of photoacoustic images of the region based on the photoacoustic waves detected.

### Claim 12 (depends on 11)

The photoacoustic imaging method of claim 11, wherein the photoacoustic images are reconstructed using universal back projection.

### Claim 13 (depends on 11)

The photoacoustic imaging method of claim 11, further comprising constructing a three dimensional volumetric image from the plurality of photoacoustic images.

### Claim 14 (depends on 11)

The photoacoustic imaging method of claim 11, wherein the photoacoustic images are taken over time.

### Claim 15 (depends on 14)

The photoacoustic imaging method of claim 14, further comprising imaging a brain function based on the photoacoustic images taken over time.

### Claim 16

A photoacoustic imaging system, comprising:
a light delivery module comprising a diffuser configured to diffuse a laser beam to produce diffuse light, the light delivery module configured to deliver the diffuse light in transmission mode through a skull to one side of a region being imaged in a brain;
an acoustic detection module comprising an ultrasonic transducer device configured to detect photoacoustic waves transmitted from an opposing side of the region, the photoacoustic waves received by the ultrasonic transducer device through an acoustic window in the skull, the photoacoustic waves based on the diffuse light delivered to the region being imaged; and
a data acquisition module comprising one or more data acquisition systems configured to receive acoustic signals from the acoustic detection module.

### Claim 17 (depends on 16)

The photoacoustic imaging system of claim 16, wherein the light delivery module is configured to provide the diffuse light in a direction along a central axis that intersects the acoustic window.

### Claim 18 (depends on 16)

The photoacoustic imaging system of claim 16, wherein the light delivery module further comprises a photon recycling element configured to receive light reflected from the skull and reflect the light back to the skull.

### Claim 19 (depends on 18)

The photoacoustic imaging system of claim 18, wherein the diffuser is disposed within the photon recycling element.

### Claim 20 (depends on 16)

The photoacoustic imaging system of claim 16, wherein the light delivery module comprises:
a laser articulating arm configured to propagate a laser beam; and
a diffuser and a photon recycling device coupled to an end of the laser articulating arm.

### Claim 21 (depends on 20)

The photoacoustic imaging system of claim 20, wherein the diffuser and the photon recycling device comprise:
a diffuser in optical communication with one or more mirrors of the laser articulating arm to receive the laser beam, the diffuser configured to diffuse the laser beam to generate the diffuse light; and
a photon recycling element configured to receive light reflected from the skull and reflect the light received back to the skull.

### Claim 22 (depends on 21)

The photoacoustic imaging system of claim 21, wherein the photon recycling element comprises a housing within which the diffuser is disposed.

### Claim 23 (depends on 16)

The photoacoustic imaging system of claim 16, wherein the light delivery module comprises:
a fiber optic bundle having a first end and a second end, the first end in optical communication with one or more laser sources to receive a laser beam; and
a diffuser coupled to an end of the fiber optic bundle to diffuse the laser beam to produce the diffuse light.

### Claim 24 (depends on 16)

The photoacoustic imaging system of claim 16, wherein the light delivery module comprises a diffuser in optical communication over free space with one or more laser sources to receive a laser beam, the diffuser configured to diffuse the laser beam to generate the diffuse light.

### Claim 25 (depends on 16)

The photoacoustic imaging system of claim 16, wherein the acoustic detection module comprises one or more data acquisition systems.

### Claim 26 (depends on 16)

The photoacoustic imaging system of claim 16, wherein the acoustic detection module comprises an ultrasonic transducer device placed in contact with, or in close proximity to, the skull during operation.

### Claim 27 (depends on 26)

The photoacoustic imaging system of claim 26, wherein the acoustic detection module further comprises an angular scan mechanism coupled to the ultrasonic transducer device to rotate the ultrasonic transducer device during operation.