Ultrasonic diagnostic imaging of response frequency differing from transmit frequency
First Claim
1. An ultrasonic diagnostic imaging system for imaging the harmonic response of tissue inside a body with reduced clutter, comprising:
- a transit controller operable to cause the elements of an array transducer to transmit wave components which are of insufficient energy to stimulate a significant harmonic response in the near field, and which wave components are focused to develop higher intensity energy at a greater depth;
an array transducer responsive to said transmit controller for transmitting ultrasonic energy into the body at a fundamental frequency and responsive to said transmitted ultrasonic energy, for receiving ultrasonic echo signals from tissue at a harmonic of said fundamental frequency;
a beamformer which processes echo signals from the transducer elements of said array transducer to form coherent echo signals;
a circuit for passing harmonic frequency echo signals from tissue to the substantial exclusion of signals at said fundamental frequency; and
an image processor, responsive to harmonic frequency echo signals from tissue passed by said circuit, for producing an ultrasonic tissue harmonic image,whereby multipath clutter in said tissue harmonic image is substantially reduced.
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Accused Products
Abstract
An ultrasonic diagnostic imaging system and methods are described which produces ultrasonic images from harmonic echo components of a transmitted fundamental frequency. Preferably, a programmable digital filter is used to pass harmonic echo components for image processing to the exclusion of fundamental frequency signals. In a preferred embodiment, artifacts are removed by producing decorrelated replicas of the harmonic signals, which are then combined and used for imaging. To produce an image in the presence of depth dependent attenuation of high frequency echo signals, both fundamental and harmonic echo signals are processed and used to produce an image blended from components of both fundamental and harmonic echo signals.
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Citations
20 Claims
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1. An ultrasonic diagnostic imaging system for imaging the harmonic response of tissue inside a body with reduced clutter, comprising:
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a transit controller operable to cause the elements of an array transducer to transmit wave components which are of insufficient energy to stimulate a significant harmonic response in the near field, and which wave components are focused to develop higher intensity energy at a greater depth; an array transducer responsive to said transmit controller for transmitting ultrasonic energy into the body at a fundamental frequency and responsive to said transmitted ultrasonic energy, for receiving ultrasonic echo signals from tissue at a harmonic of said fundamental frequency; a beamformer which processes echo signals from the transducer elements of said array transducer to form coherent echo signals; a circuit for passing harmonic frequency echo signals from tissue to the substantial exclusion of signals at said fundamental frequency; and an image processor, responsive to harmonic frequency echo signals from tissue passed by said circuit, for producing an ultrasonic tissue harmonic image, whereby multipath clutter in said tissue harmonic image is substantially reduced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for producing an ultrasonic image from the harmonic response of tissue in the interior of the body comprising the steps of:
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transmitting ultrasonic energy from the elements of an array transducer into the body at a fundamental frequency in wave components emanating over a plurality of elements in the near field and which wave components become focused to develop harmonic frequency components at a greater death; receiving ultrasonic echo signals by said array transducer which have been returned by said tissue at a harmonic of said fundamental frequency; forming coherent echo signals from said received ultrasonic echo signals; passing tissue harmonic signals to the substantial exclusion of fundamental frequency signals; and processing said tissue harmonic signals from which fundamental frequency signals have been substantially excluded to produce ultrasonic image display signals; and displaying said ultrasonic image display signals, whereby multipath clutter in said tissue harmonic ultrasonic image is substantially reduced. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An ultrasonic diagnostic imaging system for imaging the harmonic response of tissue inside a body which exhibits depth dependent attenuation of ultrasonic energy, comprising:
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a transmit controller operable to cause the elements of an array transducer to transmit wave components, the energy of which is distributed over the array in the near field and becomes focused to develop harmonic frequency components at a focal depth; a transducer array responsive to said transmit controller for transmitting ultrasonic energy into the body at a fundamental frequency which is equal to or less than 5 MHz and which is responsive to said transmitted ultrasonic energy for receiving ultrasonic echo signals from tissue at a harmonic of said fundamental frequency which is equal to or less than 10 MHz; means for digitizing said received ultrasonic echo signals, a digital beamformer for forming coherent echo signals from said digitized ultrasonic echo signals; a filter which passes, tissue harmonic echo signals to the substantial exclusion of fundamental frequency signals; and an image processor, responsive to said tissue harmonic echo signals from which fundamental frequency signals have been substantially excluded, for producing an ultrasonic image from said tissue harmonic echo signals, whereby the multipath clutter of said image of tissue harmonic echo signals is substantially reduced. - View Dependent Claims (17, 18, 19, 20)
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Specification