Vascular plaque characterization

• US 6,200,268 B1
• Filed: 09/10/1999
• Issued: 03/13/2001
• Est. Priority Date: 09/10/1999
• Status: Expired due to Term

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Nair, Anuja, Vince, D. Geoffrey, Kuban, Barry D.
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): Imam, Ali M.
• Application Number:
  US09/394,140
• Time in Patent Office: 550 Days
• Field of Search: 600/437, 600/443, 600/447, 600/463, 600/455-456, 600/466-467, 600/471, 600/407, 128/916
• US Class Current: 600/443
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 8/0833 involving detecting or locating foreign bodies or organic structures
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/4461 Features of the scanning mechanism, e.g. for moving the transducer within the housing of the probe
• CPC Class Codes: A61B 8/469 for selection of a region of interest
• CPC Class Codes: A61B 8/5238 for combining image data of patient, e.g. merging several images from different acquisition modes into one image for image registration algorithms G06T7/30
• CPC Class Codes: G06T 2207/10132 Ultrasound image
• CPC Class Codes: G06T 2207/20104 Interactive definition of region of interest [ROI]
• CPC Class Codes: G06T 2207/30101 Blood vessel; Artery; Vein; Vascular
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/11 Region-based segmentation

Abstract

A method and system for characterizing plaque components within a vascular object is provided. The vascular object is scanned with an ultrasonic device and backscatter signal data is collected. Histology images are prepared and digitized which correspond to the scanned vascular sections. A plaque component is selected on the histology image and its coordinates are mapped to a corresponding location on an IVUS image constructed from the backscatter signal. The IVUS image location is then translated to the corresponding signal section of the raw backscatter signal. Frequency analysis is performed on the signal section to determine its signal properties. The signal properties are correlated to the selected plaque component of the histology image and stored in a plaque characterization database. The process is then repeated for all plaque components and other tissue types found within the vascular object and stored in the database. With the present invention, the components of the vascular object such as a blood vessel can be identified directly from the raw backscatter signal by matching its signal properties with the signal properties of the database, thus, identifying plaque components or other tissue components in vivo and in real-time.

Claims

1. A method of identifying components within a vascular object from an ultrasonic signal, the method comprising the steps of:

transmitting an ultrasonic signal within a selected region of the vascular object and collecting a backscatter signal reflected from the vascular object;

reconstructing an IVUS image of the selected region from the backscatter signal;

preparing a histology image of the selected region of the vascular object, the histology image distinguishing different components of the vascular object;

selecting a region of interest from the histology image, the region of interest representing one component from the different components of the vascular object and being at a coordinate location on the histology image;

mapping the coordinate location to a location on the IVUS image corresponding to the coordinate location;

translating the location on the IVUS image to a signal portion in the backscatter signal corresponding to the location, the signal portion representing a signal signature of the one component of the vascular object; and

correlating the signal signature to the one component.

2. The method of identifying components as set forth in claim 1 further including performing a signal analysis on the signal portion to determine signal properties of the signal portion, the signal signature including the signal properties.

3. The method of identifying components as set forth in claim 2 further including storing the correlated signal signature and the one component in a database.

4. The method of identifying components as set forth in claim 1 further including:

selecting another region of interest from the histology image, the another region of interest representing another component from the different components of the vascular object;

repeating the mapping, translating and correlating steps to determine another signal signature which corresponds to the another component; and

generating a database including the correlated signal signatures and the components.

5. The method of identifying components as set forth in claim 1 wherein the different components of the vascular object include plaque components.

6. The method of identifying components as set forth in claim 1 wherein the preparing includes digitizing the histology image.

7. A method of identifying components of a vascular object from an ultrasonic signal, the method comprising the steps of:

transmitting an ultrasonic signal within the vascular object, the vascular object reflecting portions of the ultrasonic signal and absorbing portions of the ultrasonic signal;

collecting the reflected portions of the ultrasonic signal as a backscatter signal, the backscatter signal including signal properties;

providing a database which associates vascular components to signal properties the database being pregenerated by correlating the vascular components from a histology image to corresponding signal properties from a backscatter signal;

comparing the signal properties of the backscatter signal to the signal properties in the database to determine a match; and

assigning a vascular component to the signal properties of the backscatter signal if a match is determined.

8. The method of identifying components of a vascular object as set forth in claim 7 further including generating an intravascular ultrasound image from the backscatter signal, the ultrasound image distinguishing different vascular components based on the vascular component assigned to the signal properties of the backscatter signal.

9. The method of identifying components of a vascular object as set forth in claim 7 further including analyzing the backscatter signal to determine the signal properties, the signal properties including at least a frequency of the backscatter signal at a plurality of segments along the backscatter signal, each segment of the plurality of segments representing signal properties of a vascular component.

10. The method of identifying components of a vascular object as set forth in claim 9 further including determining a size of the vascular component based on a size of a segment in the backscatter signal that represents the vascular component.

11. The method of identifying components of a vascular object as set forth in claim 7 wherein the transmitting includes transmitting the ultrasonic signal in a plurality of scan lines, each of the scan lines including a backscatter signal reflected from the ultrasonic signal.

12. The method of identifying components of a vascular object as set forth in claim 11 further including analyzing the backscatter signal of each scan line to determine the signal properties at each of the plurality of segments.

13. The method of identifying components of a vascular object as set forth in 7 wherein the vascular component includes plaque.

14. The method of identifying components of a vascular object as set forth in 7 wherein the database correlates a range of signal properties to a vascular component.

15. The method of identifying components of a vascular object as set forth in 7 further including determining a relationship between two vascular components within the backscatter signal based on a location of the two vascular components along the backscatter signal.

16. A method for characterizing a plaque component within a vascular object based on an ultrasonic backscatter signal collected from a selected section of the vascular object, the method comprising the steps of:

preparing a histology image of the selected section of the vascular object;

selecting an area in the histology image which represents a plaque component;

corresponding the area in the histology image to a segment of the backscatter signal, the segment including signal properties; and

associating the plaque component to the signal properties of the segment.

17. The method for characterizing a plaque component as set forth in claim 16 wherein the corresponding includes:

generating an ultrasonic image from the backscatter signal, the ultrasonic image having coordinates that correspond to coordinates of the histology image;

mapping the area in the histology image to a corresponding area in the ultrasonic image; and

determining the segment of the backscatter signal that represents the corresponding area in the ultrasonic image.

18. The method for characterizing a plaque component as set forth in claim 16 further including performing a frequency analysis on the backscatter signal to determine the signal properties of the segment, the signal properties including at least a frequency of the segment.

19. The method for characterizing a plaque component as set forth in claim 18 further including performing a power spectrum analysis on the backscatter signal to determine power properties of the segment.