Methods and systems for ultrasound scanning using spatially and spectrally separated transmit ultrasound beams

A method of scanning tissue in a body using transmit ultrasound beams, the method comprising the step of transmitting a plurality of transmit ultrasound beams in a plurality of directions in the body at a series of start times from an ultrasound transducer, each of the plurality of transmit ultrasound beams being transmitted at one of a plurality of frequencies, wherein a time interval from a first start time of one of the plurality of transmit ultrasound beams to a second start time of another of the plurality of transmit ultrasound beams is less than a total time for one of the plurality of transmit ultrasound beams to propagate to a maximum scan range in the region and a corresponding reflected pressure wave to propagate from the maximum scan range to the ultrasound transducer.

A method for reducing speckle in ultrasound images of tissue in a body comprising the steps of:

• transmitting a first transmit ultrasound beam at a first frequency in a first direction and a second transmit ultrasound beam at a second frequency in a second direction, the first and second directions defining a separation angle therebetween, wherein a time interval from a first start time of the first transmit ultrasound beam to a second start time of the second transmit ultrasound beam is less than a total time for the first transmit ultrasound beam to propagate from an ultrasound transducer array to a maximum scan range in the region and a corresponding reflected pressure wave to propagate from the maximum scan range to the ultrasound transducer array;
• and
• transmitting a third transmit ultrasound beam at a third frequency in a third direction, substantially adjacent to the first direction, and a fourth transmit ultrasound beam at a fourth frequency in a fourth direction, substantially adjacent to the second direction, the third and fourth directions defining a separation angle therebetween, wherein the third and fourth transmit ultrasound beams are transmitted prior to expiration of the time interval.

A system that scans tissue in a body using transmit ultrasound beams, the system comprising:

• means for generating a first plurality of signals having an associated first frequency to cause an ultrasound transducer array to transmit a first transmit ultrasound beam at the first frequency in a first direction;
• and
• means for generating a second plurality of signals having an associated second frequency that is different than the first frequency to cause an ultrasound transducer array to transmit a second transmit ultrasound beam at the second frequency in a second direction, wherein a time interval from a first start time of the first transmit ultrasound beam to a second start time of the second transmit ultrasound beams is less than a total time for the first transmit ultrasound beam to propagate from the ultrasound transducer array to a maximum scan range in the region and a corresponding reflected pressure wave to propagate from the maximum scan range to the ultrasound transducer array.

A system that scans tissue in a body using transmit ultrasound beams, the system comprising:

• means for transmitting a first transmit ultrasound beam at a first frequency in a first direction from an ultrasound transducer at a first start time to a maximum scan range to produce a corresponding reflected pressure wave;
• and
• means for transmitting a second transmit ultrasound beam at a second frequency, that is different than the first frequency, in a second direction in the region at a second start time that follows the first start time, wherein a time interval between the first start time of one of the plurality of transmit ultrasound beams and the second start time of another of the plurality of transmit ultrasounds beams is less than a total time for one of the plurality of transmit ultrasound beams to propagate to the maximum scan range in the region and the corresponding reflected pressure wave to propagate from the maximum scan range to the ultrasound transducer.

A system for reducing speckle in ultrasound images comprising:

• means for transmitting a first transmit ultrasound beam at a first frequency in a first direction and a second transmit ultrasound beam at a second frequency in a second direction, the first and second directions defining a separation angle therebetween, wherein a time interval from a first start time of the first transmit ultrasound beam to a second start time of the second transmit ultrasound beams is less than a total time for the first transmit ultrasound beam to propagate from an ultrasound transducer array to a maximum scan range in the region and a corresponding reflected pressure wave to propagate from the maximum scan range to the ultrasound transducer array;
• and
• means for transmitting a third transmit ultrasound beam at a third frequency in a third direction, substantially adjacent to the first direction, and a fourth transmit ultrasound beam at a fourth frequency in a fourth direction, substantially adjacent to the second direction, the third and fourth directions defining a separation angle therebetween, wherein the third and fourth transmit ultrasound beams are transmitted prior to expiration of the time interval.

A method of scanning tissue in a body using transmit ultrasound beams, the method comprising the steps of:

• transmitting a first transmit ultrasound beam at a first frequency in a first direction from an ultrasound transducer array at a first start time;
• and
• transmitting a second transmit ultrasound beam at a second frequency, that is different than the first frequency, in a second direction from the ultrasound transducer array at a second start time that follows the first start time, wherein the time interval between the first start time and the second start time is less than a total time for the first transmit ultrasound beam to propagate from the ultrasound transducer array to a maximum scan range in the region and a corresponding reflected pressure wave to propagate from the maximum scan range to the ultrasound transducer array, and wherein the first and second frequencies are selected to reduce interference between reflected pressure waves generated within the maximum scan range.

A method for reducing speckle in ultrasound images of tissue in a body comprising the steps of:

• transmitting a first transmit ultrasound beam at a first frequency in a first direction;
• and
• transmitting a second transmit ultrasound beam at a second frequency in a second direction, the first and second directions defining a separation angle therebetween in a range between about 10 and 30 about degrees, wherein a time interval from a first start time of the first transmit ultrasound beam to a second start time of the second transmit ultrasound beam is less than a total time for the first transmit ultrasound beam to propagate from an ultrasound transducer array to a maximum scan range in the region and a corresponding reflected pressure wave to propagate from the maximum scan range to the ultrasound transducer array.