Methods and apparatus for blood speckle detection in an intravascular ultrasound imaging system
First Claim
1. A method of distinguishing tissue from blood in an intravascular ultrasound blood vessel image, said method comprising the steps of:
- illuminating an intravascular target with ultrasonic RF energy to generate ultrasonic echoes from said intravascular target;
transforming the ultrasonic echoes from the intravascular target into a received RF signal;
performing spectral analysis on at least a portion of said received RF signal to provide intensity information on the spectrum of said received RF signal, said information including a first intensity strength at a high frequency within said spectrum and a second intensity strength at a low frequency within said spectrum;
comparing said first intensity strength and said second intensity strength;
determining that said intravascular target is tissue if said first intensity strength and said second intensity strength are approximately equal and that said intravascular target is blood if said first intensity strength is greater than said second intensity strength, wherein said determining step takes into account tissue and blood backscatter strength sensitivities at said high and low frequencies.
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Abstract
Methods and apparatus for blood speckle detection for enhanced intravascular ultrasound imaging. The present invention utilizes the fact that the energy scattering strength from blood exhibits a high frequency dependency, while the scattering strength from tissue lacks a strong frequency dependency. In specific embodiments, the present invention may provide a particularly simple and useful solution for addressing the problem of blood speckle in intravascular ultrasound imaging, especially in situations where the blood may have a scattering strength similar to that of tissue and/or where the blood is moving slowly or not at all.
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Citations
20 Claims
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1. A method of distinguishing tissue from blood in an intravascular ultrasound blood vessel image, said method comprising the steps of:
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illuminating an intravascular target with ultrasonic RF energy to generate ultrasonic echoes from said intravascular target; transforming the ultrasonic echoes from the intravascular target into a received RF signal; performing spectral analysis on at least a portion of said received RF signal to provide intensity information on the spectrum of said received RF signal, said information including a first intensity strength at a high frequency within said spectrum and a second intensity strength at a low frequency within said spectrum; comparing said first intensity strength and said second intensity strength; determining that said intravascular target is tissue if said first intensity strength and said second intensity strength are approximately equal and that said intravascular target is blood if said first intensity strength is greater than said second intensity strength, wherein said determining step takes into account tissue and blood backscatter strength sensitivities at said high and low frequencies. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17)
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14. A method of distinguishing tissue from blood in an intravascular ultrasound blood vessel image, said method comprising the steps of:
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illuminating an intravascular target with ultrasonic RF energy at a first frequency to generate ultrasonic echoes from said intravascular target to form a first image frame; illuminating said intravascular target with ultrasonic RF energy at a second frequency to generate ultrasonic echoes from said intravascular target to form a second image frame, wherein said first and second image frames are successive in time and wherein one of said first and second frequencies is a low frequency and another one of said first and second frequencies is a high frequency; subtracting said first and second image frames to obtain a subtracted image frame; determining that portions of said subtracted image frame that are substantially cancelled-out are tissue and that portions of said subtracted image frame that are not cancelled-out are blood, wherein said determining step takes into account tissue and blood backscatter strength sensitivities at said high and low frequencies.
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18. Apparatus for an ultrasonic blood vessel imaging system comprising:
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a transducer having a frequency bandwidth including known and sufficiently high strength sensitivities at a first frequency and a second frequency, said transducer obtaining echoes from an intravascular target using ultrasounds transmitted at said first and said second frequencies to form an intravascular image, wherein said first and second frequencies are between a -3 dB low frequency and a -3 dB high frequency of said transducer; a signal processing device capable of being coupled to said transducer and to a display for displaying said intravascular image; a computer-readable medium storing a computer-readable program, said computer-readable medium coupled to be read by said signal processing device, said computer-readable program for comparing a first intensity strength for echoes from ultrasound at said first frequency with a second intensity strength for echoes from ultrasound at said second frequency to detect blood speckle in said intravascular image. - View Dependent Claims (19, 20)
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Specification