Method and apparatus for in vitro analysis of the physical response of blood-vessels to vaso-active agents

1. A method comprising:

capturing a first image of a blood vessel sample at a time prior to application of a vaso-active agent to the blood vessel sample, wherein a timestamp is associated with the image;

determining, by a computing device, a first hue value, a first saturation value, and a first intensity value for each of a first plurality of pixels in a region of interest of the first image of the blood vessel sample;

capturing a plurality of subsequent images of the blood vessel sample during and after application of the vaso-active agent to the blood vessel sample, wherein a timestamp is associated with each subsequent image;

determining, by the computing device, for each subsequent image, a subsequent hue value, a subsequent saturation value, and a subsequent intensity value for each of a plurality of pixels in the region of interest of the subsequent image of the blood vessel sample;

determining, by the computing device, a first number of pixels that correspond to a lumen of the blood vessel sample based at least in part on the first hue value, the first saturation value, and the first intensity value of each of the first plurality of pixels in the region of interest of the first image;

determining, by the computing device, a first area of the lumen of the blood vessel sample based on the first number of pixels and a known area of a single pixel;

determining, by the computing device, for each of the plurality of subsequent images, a subsequent number of pixels that correspond to the lumen of the blood vessel sample based at least in part on the subsequent hue value, the subsequent saturation value, and the subsequent intensity value of each of the subsequent plurality of pixels in the region of interest of the subsequent image;

determining, by the computing device, for each of the plurality of subsequent images, a subsequent area of the lumen of the blood vessel sample based on the subsequent number of pixels and the known area of the single pixel;

determining, by the computing device, a physical response of the blood vessel sample to a vaso-active agent based at least in part on a comparison of the determined areas of the lumen of the blood vessel sample, wherein the physical response comprises a change in area of the lumen of the blood vessel sample; and

plotting, by the computing device, the change in area of the lumen as a function of time.

2. The method of claim 1 , further comprising:

generating, for each image, a hue image based at least in part on the hue value for each of the plurality of pixels in the region of interest of the image, a saturation image based at least in part on the saturation value for each of the plurality of pixels in the region of interest of the image, and an intensity image based at least in part on the intensity value for each of the plurality of pixels in the region of interest of the image; and

generating, for each image, a normalized hue histogram based at least in part on the hue image, a normalized saturation histogram based at least in part on the saturation image, and a normalized intensity histogram based at least in part on the intensity image.

3. The method of claim 2 , further comprising:

Determining, for each image, a hue threshold based at least in part on the normalized hue histogram, a saturation threshold based at least in part on the normalized saturation histogram, and an intensity threshold based at least in part on the normalized intensity histogram;

comparing, for each image, the hue value for each of the plurality of pixels in the region of interest of the image to the hue threshold, the saturation value for each of the plurality of pixels in the region of interest of the image to the saturation threshold, and the intensity value for each of the plurality of pixels in the region of interest of the image to the intensity threshold; and

determining, for each image, based at least in part on the comparison, whether a pixel of the plurality of pixels in the region of interest of the image corresponds to tissue of the blood vessel sample or to the lumen of the blood vessel sample.

4. The method of claim 3 , wherein one or more of the hue threshold, the saturation threshold, and the intensity threshold are determined using a maximum entropy principle.

5. The method of claim 1 , further comprising generating, for each image, a histogram based at least in part on one or more of the hue value, the saturation value, and the intensity value for each of the plurality of pixels in the region of interest of the image.

6. The method of claim 5 , further comprising:

identifying a peak of each histogram; and

determining an area of the peak of each histogram, wherein the physical response of the blood vessel sample is based at least in part on the area of the peak of the histogram, and wherein the area of the peak of the histogram corresponds to the area of the lumen of the blood vessel sample.

7. The method of claim 1 , further comprising applying the vaso-active agent to at least a portion of the blood vessel sample.

8. The method of claim 1 , further comprising:

receiving a specification of the region of interest on the first image, wherein the region of interest includes at least the lumen of the blood vessel sample; and

transposing the region of interest onto the subsequent images of the blood vessel sample.

9. The method of claim 1 , further comprising determining, for each image, a normalized value for each of the plurality of pixels in the region of interest of the image based at least in part on of the hue value, the saturation value, and the intensity value for each of the plurality of pixels in the region of interest of the image, wherein the area of the lumen is determined based at least in part on the normalized value.

10. The method of claim 1 , further comprising determining, for each image, a red value, a green value, and a blue value for each of the plurality of pixels in the region of interest of the image, wherein the hue value, the saturation value, and the intensity value are based at least in part on the red value, the green value, and the blue value.

11. A system comprising:

a memory configured to store a first image of a blood vessel sample captured at time prior to application of a vaso-active agent to the blood vessel sample, wherein a timestamp is associated with the image;

the memory configured to store a plurality of subsequent images of the blood vessel sample captured during and after application of the vaso-active agent to the blood vessel sample, wherein a timestamp is associated with each subsequent image; and

a processor operatively coupled to the memory and configured to:

determine a first hue value, a first saturation value, and a first intensity value for each of a first plurality of pixels in a region of interest of the first image of the blood vessel sample;

determine, for each subsequent image, a subsequent hue value, a subsequent saturation value, and a subsequent intensity value for each of a subsequent plurality of pixels in the region of interest of the subsequent image of the blood vessel sample;

determine a first number of pixels that correspond to a lumen of the blood vessel sample based at least in part on the first hue value, the first saturation value, and the first intensity value of each of the first plurality of pixels in the region of interest of the first image;

determine a first area of the lumen of the blood vessel sample based on the first number of pixels and a known area of a single pixel;

determine, for each of the plurality of subsequent images, a subsequent number of pixels that correspond to the lumen of the blood vessel sample based at least in part on the subsequent hue value, the subsequent saturation value, and the subsequent intensity value of each of the subsequent plurality of pixels in the region of interest of the subsequent image;

determine, for each of the plurality of subsequent images, a subsequent area of the lumen of the blood vessel sample based on the subsequent number of pixels and the known area of the single pixel;

determine a physical response of the blood vessel sample to a vaso-active agent based at least in part on a comparison of the determined areas of the lumen of the blood vessel sample, wherein the physical response comprises a change in area of the lumen of the blood vessel sample; and

plot the change in area of the lumen as a function of time.

12. The system of claim 11 , further comprising:

a chamber configured to receive the blood vessel sample and the vaso-active agent that is applied to the blood vessel sample; and

a camera configured to capture the first image and the subsequent images of the blood vessel sample.

13. The system of claim 11 , further comprising a light source configured to illuminate the blood vessel sample, wherein the light source is mounted underneath a sample platform of a microscope.

14. The system of claim 11 , wherein the processor is further configured to identify, for each image, a red value, a green value, and a blue value for each of the plurality of pixels in the region of interest of the image, and wherein the hue value, the saturation value, and the intensity value are determined based at least in part on the red value, the green value, and the blue value.

15. The system of claim 11 , wherein the processor is further configured to:

generate, for each image, a histogram based at least in part on the hue value, the saturation value, and the intensity value for each of the plurality of pixels in the region of interest of the image; and

determine, for each image, a hue threshold, a saturation threshold, and an intensity threshold based at least in part on the histogram, wherein the number of pixels that correspond to the lumen of the blood vessel sample is determined based at least in part on the hue threshold, the saturation threshold, and the intensity threshold.

16. A non-transitory computer-readable medium having instructions stored thereon that, when executed by a processor, cause the processor to perform the following operations:

store, in a memory, a first image of a blood vessel sample captured at time prior to application of a vaso-active agent to the blood vessel sample, wherein a timestamp is associated with the image;

store, in the memory, a plurality of subsequent images of the blood vessel sample captured during and after application of the vaso-active agent to the blood vessel sample, wherein a timestamp is associated with each subsequent image; and

determine a first hue value, a first saturation value, and a first intensity value for each of a first plurality of pixels in a region of interest of a first image of a blood vessel sample;

determine, for each of the plurality of subsequent images, a subsequent hue value, a subsequent saturation value, and a subsequent intensity value for each of a subsequent plurality of pixels in the region of interest of a subsequent image of the blood vessel sample;

determine a first number of pixels that correspond to a lumen of the blood vessel sample based at least in part on the first hue value, the first saturation value, and the first intensity value of each of the first plurality of pixels in the region of interest of the first image;

determine a first area of the lumen of the blood vessel sample based on the first number of pixels and a known area of a single pixel;

determine, for each of the plurality of subsequent images, a subsequent number of pixels that correspond to the lumen of the blood vessel sample based at least in part on subsequent hue value, the subsequent saturation value, and the subsequent intensity value of each of subsequent plurality of pixels in the region of interest of the subsequent image;

determine, for each of the plurality of subsequent images, a subsequent area of the lumen of the blood vessel sample based on the second number of pixels and the known area of the single pixel;

instructions for determining a physical response of the blood vessel sample to a vaso-active agent based at least in part on a comparison of the determined areas of the lumen of the blood vessel sample, wherein the physical response comprises a change in area of the lumen of the blood vessel sample; and

plot the change in area of the lumen as a function of time.

17. The non-transitory computer-readable medium of claim 16 , further comprising instructions to cause the processor to transpose the region of interest of the first image onto the subsequent images of the blood vessel sample, wherein the region of interest includes at least the lumen of the blood vessel sample.

18. The non-transitory computer-readable medium of claim 16 , further comprising instructions to cause the processor to perform the following operations:

generate, for each image, a hue image based at least in part on the hue value for each of the plurality of pixels in the region of interest of the image, a saturation image based at least in part on the first saturation value for each of the plurality of pixels in the region of interest of the image, and an intensity image based at least in part on the intensity value for each of the first plurality of pixels in the region of interest of the image;

generate, for each image, a normalized hue histogram based at least in part on the hue image, a normalized saturation histogram based at least in part on the saturation image, and a normalized intensity histogram based at least in part on the intensity Image;

determine, for each image, a hue threshold based at least in part on the normalized hue histogram, a saturation threshold based at least in part on the normalized saturation histogram, and an intensity threshold based at least in part on the normalized intensity histogram;

comparing, for each image, the hue value to the hue threshold, the saturation value to the saturation threshold, and the intensity value to the intensity threshold; and

determine, for each image, based at least in part on the comparison, whether each of the first plurality of pixels in the region of interest of the image correspond to tissue of the blood vessel sample or to the lumen of the blood vessel sample.