Detection of immobilized contrast agent with dynamic thresholding

• US 10,433,817 B2
• Filed: 12/06/2016
• Issued: 10/08/2019
• Est. Priority Date: 12/10/2015
• Status: Active Grant

• Current Assignee: Bracco Suisse SA
• Original Assignee: Bracco Suisse SA
• Inventors: Frinking, Peter, Hyvelin, Jean-Marc, Fresneau, Thomas
• Primary Examiner(s): Strege, John B
• Application Number:
  US15/781,088
• Publication Number:
  US 20180353158A1
• Time in Patent Office: 1,036 Days
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/481 involving the use of contrast agent, e.g. microbubbles introduced into the bloodstream analysis of echo signal exploiting properties of a contrast enhancer in devices for short-range imaging with acoustic waves G01S7/52039
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: A61B 8/5246 combining images from the same or different imaging techniques, e.g. color Doppler and B-mode
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10132 Ultrasound image
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A solution is proposed for analyzing a body-part of a patient, the body-part having been perfused before performing the method with a contrast agent capable of circulating within the patient and of being substantially immobilized on a biological target. A corresponding method comprises providing at least one filtered image comprising a plurality of filtered values for corresponding locations of the body-part, each filtered value comprising an indication of the immobilized contrast agent at the corresponding location with a contribution of the circulating contrast agent being substantially reduced, generating a thresholded image comprising a plurality of thresholded values corresponding to the filtered values, the thresholded image being generated by setting each thresholded value to the corresponding filtered value or to a reset value according to a comparison of the filtered value with an amplitude threshold, providing a plurality of candidate thresholds defined by corresponding candidate values of the amplitude threshold, generating a plurality of candidate images corresponding to the candidate thresholds each one comprising a plurality of candidate values corresponding to the filtered values, each candidate image being generated by setting each candidate value to the corresponding filtered value or to the reset value according to said comparison of the filtered value with the candidate threshold, calculating a plurality of comparison values corresponding to the candidate images, the comparison value of each candidate image being calculated according to a further comparison between the candidate values in an immobilization region corresponding to a group of locations containing a significant amount of the immobilized contrast agent and the candidate values in a circulation region corresponding to at least part of the locations excluding the immobilization region, determining a peak of the comparison values, and setting the amplitude threshold according to the peak of the comparison values.

Claims

1. A method for analyzing a body-part of a patient, the body-part having been perfused before performing the method with a contrast agent capable of circulating within the patient and of being substantially immobilized on a biological target, wherein the method comprises:

providing at least one filtered image comprising a plurality of filtered values for corresponding locations of the body-part, each filtered value comprising an indication of the immobilized contrast agent at the corresponding location with a contribution of the circulating contrast agent being substantially reduced,

generating a thresholded image comprising a plurality of thresholded values corresponding to the filtered values, the thresholded image being generated by setting each thresholded value to the corresponding filtered value or to a reset value according to a comparison of the filtered value with an amplitude threshold,

providing a plurality of candidate thresholds defined by corresponding candidate values of the amplitude threshold,

generating a plurality of candidate images corresponding to the candidate thresholds each one comprising a plurality of candidate values corresponding to the filtered values, each candidate image being generated by setting each candidate value to the corresponding filtered value or to the reset value according to said comparison of the filtered value with the candidate threshold,

calculating a plurality of comparison values corresponding to the candidate images, the comparison value of each candidate image being calculated according to a further comparison between the candidate values in an immobilization region corresponding to a group of locations containing a significant amount of the immobilized contrast agent and the candidate values in a circulation region corresponding to at least part of the locations excluding the immobilization region,

determining a peak of the comparison values, and

setting the amplitude threshold according to the peak of the comparison values.

2. The method according to claim 1, wherein the method comprises:

displaying the thresholded image.

3. The method according to claim 1, wherein said providing at least one filtered image comprises:

providing a plurality of original images, corresponding to successive acquisition instants during an analysis period of the body-part after the administration of the contrast agent, each one comprising a plurality of original values corresponding to the filtered values, each original value being indicative of a response to an interrogation signal of the corresponding location, and

generating the filtered image from at least part of the original images by substantially reducing the contribution of the circulating contrast agent, and wherein said providing a plurality of candidate thresholds comprises;

calculating a base threshold according to at least part of the original values of said at least part of the original images, and

calculating the candidate thresholds according to the base threshold.

4. The method according to claim 3, wherein the body-part comprises a tissue, said providing at least one filtered image comprising:

processing the original images to substantially reduce a contribution of the tissue before said generating the filtered image.

5. The method according to claim 3, wherein said generating the filtered image comprises:

setting each filtered value to one of the original values indicative of a lowest one of the responses to the interrogation signal of the corresponding location in a filtering set of the original images consisting of one of the original images corresponding to the filtered image and at least one of the original images preceding the original image corresponding to the filtered image.

6. The method according to claim 3, wherein said calculating the candidate thresholds comprises:

setting the candidate thresholds to corresponding percentages of the base threshold.

7. The method according to claim 6, wherein said percentages are distributed uniformly from 0-50% to 150-250%.

8. The method according to claim 3, wherein said calculating a base threshold comprises:

setting the base threshold according to the original values in the circulation region of said at least part of the original images.

9. The method according to claim 8, wherein said calculating a base threshold comprises:

setting the base threshold according to a median of the original values in the circulation region of each one of said at least part of the original images.

10. The method according to claim 1, wherein said calculating a plurality of comparison values comprises, for each candidate image:

calculating a consolidated immobilization value according to the candidate values in the immobilization region,

calculating a consolidated circulation value according to the candidate values in the circulation region, and

calculating the comparison value according to a comparison between the consolidated immobilization value and the consolidated circulation value.

11. The method according to claim 10, wherein said calculating a plurality of comparison values comprises, for each candidate image:

setting the consolidated immobilization value to a mean of the candidate values in the immobilization region,

setting the consolidated circulation value to a mean of the candidate values in the circulation region, and

setting the comparison value to a difference between the consolidated immobilization value and the consolidated circulation value.

12. The method according to claim 10, wherein said calculating a plurality of comparison values comprises, before said calculating the comparison value:

normalizing the consolidated immobilization values to the consolidated immobilization value corresponding to a bound value of the candidate thresholds, and

normalizing the consolidated circulation values to the consolidated circulation value corresponding to the bound value of the candidate thresholds.

13. The method according to claim 1, wherein said calculating a plurality of comparison values comprises:

smoothing the comparison values before said determining a peak.

14. The method according to claim 1, wherein said setting the amplitude threshold comprises:

determining the amplitude threshold for providing a percentage of a peak value of the comparison values with a thresholding level higher than the thresholding level of a peak threshold of the candidate thresholds providing the peak value.

15. The method according to claim 14, wherein said percentage of the peak value is 40-60% of the peak value.

16. The method according to claim 14, wherein said setting the amplitude threshold comprises:

setting the amplitude threshold to the candidate threshold higher than the peak threshold and providing the comparison value being closest to the percentage of the peak value.

21. A diagnostic method for analyzing a body-part of a patient, the diagnostic method comprising:

administering a contrast agent to the patient to cause the body-part to be perfused with the contrast agent, the contrast agent being capable of circulating within the patient and of being substantially immobilized on a biological target,

acquiring at least one filtered image comprising a plurality of filtered values for corresponding locations of the body-part, each filtered value comprising an indication of the immobilized contrast agent at the corresponding location with a contribution of the circulating contrast agent being substantially reduced, the filtered image being processed according to the method of claim 1 to obtain the corresponding thresholded image, and

evaluating a condition of the body-part according to the thresholded image.

17. A non-transitory computer-readable medium storing a computer program configured for causing a computing system to perform a method for analyzing a body-part of a patient when the computer program is executed on the computing system, the body-part having been perfused before performing the method with a contrast agent capable of circulating within the patient and of being substantially immobilized on a biological target, wherein the method comprises:

providing at least one filtered image comprising a plurality of filtered values for corresponding locations of the body-part, each filtered value comprising an indication of the immobilized contrast agent at the corresponding location with a contribution of the circulating contrast agent being substantially reduced,

generating a thresholded image comprising a plurality of thresholded values corresponding to the filtered values, the thresholded image being generated by setting each thresholded value to the corresponding filtered value or to a reset value according to a comparison of the filtered value with an amplitude threshold,

providing a plurality of candidate thresholds defined by corresponding candidate values of the amplitude threshold,

generating a plurality of candidate images corresponding to the candidate thresholds each one comprising a plurality of candidate values corresponding to the filtered values, each candidate image being generated by setting each candidate value to the corresponding filtered value or to the reset value according to said comparison of the filtered value with the candidate threshold,

calculating a plurality of comparison values corresponding to the candidate images, the comparison value of each candidate image being calculated according to a further comparison between the candidate values in an immobilization region corresponding to a group of locations containing a significant amount of the immobilized contrast agent and the candidate values in a circulation region corresponding to at least part of the locations excluding the immobilization region,

determining a peak of the comparison values, and

setting the amplitude threshold according to the peak of the comparison values.

18. A computer program product comprising a computer readable storage medium embodying a computer program, the computer program being loadable into a working memory of a computing system thereby configuring the computing system to perform a method for analyzing a body-part of a patient, the body-part having been perfused before performing the method with a contrast agent capable of circulating within the patient and of being substantially immobilized on a biological target, wherein the method comprises:

providing at least one filtered image comprising a plurality of filtered values for corresponding locations of the body-part, each filtered value comprising an indication of the immobilized contrast agent at the corresponding location with a contribution of the circulating contrast agent being substantially reduced,

generating a thresholded image comprising a plurality of thresholded values corresponding to the filtered values, the thresholded image being generated by setting each thresholded value to the corresponding filtered value or to a reset value according to a comparison of the filtered value with an amplitude threshold,

providing a plurality of candidate thresholds defined by corresponding candidate values of the amplitude threshold,

generating a plurality of candidate images corresponding to the candidate thresholds each one comprising a plurality of candidate values corresponding to the filtered values, each candidate image being generated by setting each candidate value to the corresponding filtered value or to the reset value according to said comparison of the filtered value with the candidate threshold,

calculating a plurality of comparison values corresponding to the candidate images, the comparison value of each candidate image being calculated according to a further comparison between the candidate values in an immobilization region corresponding to a group of locations containing a significant amount of the immobilized contrast agent and the candidate values in a circulation region corresponding to at least part of the locations excluding the immobilization region,

determining a peak of the comparison values, and setting the amplitude threshold according to the peak of the comparison values.

19. A system comprising means configured for performing the steps of a method for analyzing a body-part of a patient, the body-part having been perfused before performing the method with a contrast agent capable of circulating within the patient and of being substantially immobilized on a biological target, wherein the method comprises:

providing at least one filtered image comprising a plurality of filtered values for corresponding locations of the body-part, each filtered value comprising an indication of the immobilized contrast agent at the corresponding location with a contribution of the circulating contrast agent being substantially reduced,

generating a thresholded image comprising a plurality of thresholded values corresponding to the filtered values, the thresholded image being generated by setting each thresholded value to the corresponding filtered value or to a reset value according to a comparison of the filtered value with an amplitude threshold,

providing a plurality of candidate thresholds defined by corresponding candidate values of the amplitude threshold,

generating a plurality of candidate images corresponding to the candidate thresholds each one comprising a plurality of candidate values corresponding to the filtered values, each candidate image being generated by setting each candidate value to the corresponding filtered value or to the reset value according to said comparison of the filtered value with the candidate threshold,

calculating a plurality of comparison values corresponding to the candidate images, the comparison value of each candidate image being calculated according to a further comparison between the candidate values in an immobilization region corresponding to a group of locations containing a significant amount of the immobilized contrast agent and the candidate values in a circulation region corresponding to at least part of the locations excluding the immobilization region,

determining a peak of the comparison values, and

setting the amplitude threshold according to the peak of the comparison values.

20. A system comprising a circuitry for performing each step of a method for analyzing a body-part of a patient, the body-part having been perfused before performing the method with a contrast agent capable of circulating within the patient and of being substantially immobilized on a biological target, wherein the method comprises:

providing at least one filtered image comprising a plurality of filtered values for corresponding locations of the body-part, each filtered value comprising an indication of the immobilized contrast agent at the corresponding location with a contribution of the circulating contrast agent being substantially reduced,

generating a thresholded image comprising a plurality of thresholded values corresponding to the filtered values, the thresholded image being generated by setting each thresholded value to the corresponding filtered value or to a reset value according to a comparison of the filtered value with an amplitude threshold,

providing a plurality of candidate thresholds defined by corresponding candidate values of the amplitude threshold,

generating a plurality of candidate images corresponding to the candidate thresholds each one comprising a plurality of candidate values corresponding to the filtered values, each candidate image being generated by setting each candidate value to the corresponding filtered value or to the reset value according to said comparison of the filtered value with the candidate threshold,

calculating a plurality of comparison values corresponding to the candidate images, the comparison value of each candidate image being calculated according to a further comparison between the candidate values in an immobilization region corresponding to a group of locations containing a significant amount of the immobilized contrast agent and the candidate values in a circulation region corresponding to at least part of the locations excluding the immobilization region,

determining a peak of the comparison values, and

setting the amplitude threshold according to the peak of the comparison values.