Pulsed ultrasound modulated optical tomography with increased optical/ultrasound pulse ratio

Patent metadata

Field	Value
Publication number	US-10299682-B1
Application number	US-201715844398-A
Country	US
Kind code	B1
Filing date	Dec 15, 2017
Priority date	Nov 22, 2017
Publication date	May 28, 2019
Grant date	May 28, 2019

Abstract

A system and method of performing ultrasound modulated optical tomography. Ultrasound is delivered into a target voxel in an anatomical structure, and sample light is delivered into the anatomical structure, whereby a portion of the sample light passing through the target voxel is scattered by the biological tissue as signal light, and a portion of the sample light not passing through the target voxel is scattered by the anatomical structure as background light. The ultrasound and sample light are pulsed in synchrony, such that only the signal light is frequency shifted by the ultrasound. Multiple pulses of the sample light are delivered into the anatomical structure for each pulse of the ultrasound delivered into the target voxel. Reference light is combined with the signal light and background light to generate an interference light pattern, which is sequentially modulated to generate different interference light patterns, which are detected.

First claim

What is claimed is:

1. An ultrasound modulated optical tomography (UOT) system, comprising:
an acoustic assembly configured for delivering ultrasound into a target voxel in an anatomical structure;
an interferometer configured for delivering sample light into the anatomical structure, whereby a portion of the sample light passing through the target voxel is scattered by the anatomical structure as signal light, and another portion of the sample light not passing through the target voxel is scattered by the anatomical structure as background light that combines with the signal light to create a sample light pattern, the interferometer further configured for combining reference light with the sample light pattern to generate an interference light pattern;
a controller configured for operating the acoustic assembly and the interferometer to pulse the ultrasound and the sample light in synchrony, such that only the signal light is frequency shifted by the ultrasound, wherein a duration of each pulse of the ultrasound delivered into the target voxel is within a decorrelation time of the target voxel, and wherein multiple pulses of the sample light are sequentially delivered into the anatomical structure for each pulse of the ultrasound delivered into the target voxel, the controller further configured for operating the interferometer to sequentially modulate the interference light pattern to generate a plurality of different interference light patterns;
at least one detector configured for detecting the different interference light patterns; and
a processor configured for determining a physiologically-dependent optical parameter of the target voxel based on the detected interference light patterns.

2. The UOT system of claim 1 , wherein the at least one detector comprises an array of detectors configured for respectively detecting spatial components of each different interference light pattern, wherein the processor is configured for determining the physiologically-dependent optical parameter of the target voxel based on the detected spatial components.

3. The UOT system of claim 2 , wherein each detector, in response to external trigger signals generated by the controller, is configured for respectively storing a plurality of values in a plurality of data storing bins representative of the respective spatial components of the interference light patterns, wherein the processor is configured for determining the physiologically-dependent optical parameter of the target voxel based on the plurality of values stored in the data storing bins of each detector.

4. The UOT system of claim 1 , wherein the physiologically-dependent optical parameter is the level of deoxygenated and/or oxygenated hemoglobin concentration or relative abundance.

5. The UOT system of claim 1 , wherein the physiologically-dependent optical parameter is the level of water concentration or relative water concentration of brain matter.

6. The UOT system of claim 5 , wherein the wavelength of the sample light is in the range of 950-1080 nanometers.

7. The UOT system of claim 1 , wherein the anatomical structure is a head, the system further comprising a wearable unit configured for being affixed to the head, the wearable unit comprising the acoustic assembly and the interferometer.

8. The UOT system of claim 1 , wherein the target voxel comprises brain matter, and the processor is configured for determining whether or not neural activity exists within the target voxel based on the determined physiologically-dependent optical parameter.

9. The UOT system of claim 1 , wherein the interferometer is configured for sequentially modulating the interference light pattern by phase modulating the interference light pattern.

10. The UOT system of claim 9 , wherein the interferometer is configured for phase modulating the interference light pattern by respectively setting different phases between sequential pulses of the sample light and the reference light.

11. The UOT system of claim 10 , wherein the different phases are 0, π/2, π, and 3π/2.

12. The UOT system of claim 1 , wherein the pulses of the sample light are identical.

13. The UOT system of claim 12 , wherein the interferometer comprises:
at least one 1×N fiber splitter configured for splitting a single optical pulse into an N number of identical light pulses;
an N number of optical fibers configured for propagating the N number of identical light pulses, wherein the N number of optical fibers are of different lengths, such that the N number of identical light pulses are temporally spaced apart;
at least one N×1 fiber coupler configured for temporally combining the N number of identical light pulses; and
a single optical fiber for propagating the N number of temporally combined identical light pulses as the sample light pulses.

14. The UOT system of claim 1 , wherein the interferometer is configured for combining the reference light with the signal light using a homodyne technique.

15. The UOT system of claim 14 , wherein the interferometer is further configured for frequency shifting the sample light by the frequency of the ultrasound, such that the reference light is combined with the signal light using the homodyne technique.

16. The UOT system of claim 1 , wherein the interferometer comprises a light source configured for generating source light, a beam splitter configured for splitting the source light into the sample light and the reference light, and a light combiner configured for combining the reference light with the signal light and the background light to generate the interference light pattern.

17. The UOT system of claim 16 , wherein the interferometer further comprises an optical phase shifter configured for setting a phase difference between the sample light and the reference light to phase modulate the interference light pattern.

18. The UOT system of claim 3 , wherein each of the interference light patterns comprises a speckle light pattern.

19. The UOT system of claim 18 , wherein the spatial components comprise speckle grains of the speckle light pattern.

20. The UOT system of claim 3 , wherein the array of detectors is configured for respectively detecting spatial components of each different interference light pattern, and storing the plurality of values for all of the interference patterns in the plurality of data storing bins within 10 milliseconds.

21. The UOT system of claim 3 , wherein the array of detectors is configured for respectively detecting spatial components of each different interference light pattern, and storing the plurality of values for all of the interference patterns in the plurality of data storing bins within 1 microsecond to 1 millisecond.

22. The UOT system of claim 3 , wherein the processor is configured for reconstructing the amplitude of the signal light using the plurality of values stored in each of the data storing bins, and determining the physiologically-dependent optical parameter of the target voxel based on the reconstructed amplitude of the signal light.

23. The UOT system of claim 3 , wherein each value respectively stored in each of the data storing bins is an intensity of the spatial component of the respective interference light pattern, the processor is configured for using the plurality of values stored in each of the data storing bins to extract a product of the amplitude of the signal light and a known amplitude of the reference light, and determining the amplitude of the signal light fr

Assignees

• Hi Llc

Inventors

• Yang Changhuei
• Marblestone Adam
• Alford Jamu
• Sobek Daniel

Classifications

• G16H30/40

  for processing medical images, e.g. editing · CPC title

• A61B5/0066

  Optical coherence imaging · CPC title

• A61B5/6814

  Head · CPC title

• A61B5/4064

  Evaluating the brain (for intracranial pressure A61B5/031; for cerebral blood gases A61B5/14553; using EEG A61B5/369) · CPC title

• A61B5/0073

  by tomography, i.e. reconstruction of 3D images from 2D projections (A61B5/0066 takes precedence) · CPC title