Ultrasonic diagnostic imaging system for low flow rate contrast agents
First Claim
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1. A method for detecting low velocity motion of a substance which returns ultrasonic harmonic echo signals comprising:
- transmitting a first fast time ensemble of a plurality of pulses in a first direction;
transmitting a third fast time ensemble of a plurality of pulses in the first direction; and
prior to transmitting the third fast time ensemble, transmitting a second fast time ensemble in a second direction, wherein the first and third fast time ensembles comprise a slow time ensemble transmitted in the first direction.
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Abstract
An ultrasonic diagnostic imaging system and method are presented to determine low rates of blood flow using contrast agents. Pairs of differently modulated pulses are transmitted in several beam directions to acquire echoes which can be combined to separate harmonic frequencies by pulse inversion. The pulses of each pair are transmitted in rapid succession to minimize motional artifacts. The transmission in the different beam directions is time-interleaved, resulting in the sampling of each beam direction over a long ensemble time for the detection of low rates of flow.
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Citations
25 Claims
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1. A method for detecting low velocity motion of a substance which returns ultrasonic harmonic echo signals comprising:
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transmitting a first fast time ensemble of a plurality of pulses in a first direction;
transmitting a third fast time ensemble of a plurality of pulses in the first direction; and
prior to transmitting the third fast time ensemble, transmitting a second fast time ensemble in a second direction, wherein the first and third fast time ensembles comprise a slow time ensemble transmitted in the first direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
wherein Doppler processing the separated harmonic echo components comprises detecting low rates of blood flow.
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8. The method of claim 7, wherein Doppler processing the separated harmonic echo components further comprises attenuating the contributions of harmonic echo components from stationary objects.
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9. The method of claim 1, wherein transmitting a fast time ensemble comprises transmitting at least two pulses which are differently modulated in at least one of phase, polarity, or amplitude.
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10. A method for producing ultrasonic Doppler ensembles of harmonic signals comprising:
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selecting a plurality of beam directions which are to be sampled in a time-interleaved group;
transmitting a first plurality of fast time pulses in the direction of a first one of the beams;
transmitting a first plurality of fast time pulses in the directions of all of the other beams in the group before transmitting again in the first beam direction;
transmitting a second plurality of fast time pulses in the direction of the first one of the beams; and
transmitting a second plurality of fast time pulses in the directions of all of the other beams in the group before transmitting again in the first beam direction. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An ultrasonic diagnostic imaging system comprising:
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an array transducer which acts to transmit and receive in selectable beam directions;
a beamformer, coupled to the array transducer, which acts to transmit groups of two or more pulses in each beam direction in rapid succession, the transmit groups being time-interleaved over a plurality of beam directions;
a Doppler processor, coupled to the beamformer, which processes harmonic components from low flow rate substances which have been separated by the pulse inversion process. - View Dependent Claims (17, 18)
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19. A method for ultrasonically estimating the flow rate of slowly moving materials comprising:
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a) selecting a plurality of beam directions which are to be sampled in a time-interleaved manner;
b) transmitting in rapid succession in a first beam direction two pulses of a given frequency which are differently modulated in at least one of phase, polarity, or amplitude, and receiving echoes following each pulse;
c) repeating step b) in at least a second beam direction;
d) following step c), repeating step b) at least one further time in the first beam direction;
e) following step d), repeating step c) at least one further time; and
f) processing the echoes received in each beam direction to detect flow at spatial locations in each beam direction. - View Dependent Claims (20, 21, 22)
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23. A method for acquiring an ensemble of signal samples for Doppler processing comprising:
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transmitting pulses sequentially in a plurality of beam directions in an interleaved manner and acquiring echoes along a beam direction following each pulse; and
acquiring an ensemble of echoes for each beam direction, wherein the intervals between the transmit pulses of an ensemble are not all identical. - View Dependent Claims (24, 25)
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Specification