Abstract:
A method for determining a physical characteristic on a punctual location (P0) inside a medium (11), comprising the steps of: sending an emitted sequence comprising emitted pulses having different amplitudes, receiving a received sequence comprising received pulses corresponding to echoes of said emitted pulses, calculating a phase difference between the received pulses relative to the emitted pulses, and determining the physical characteristic on the bases of said phase difference.
Abstract:
This invention employs multiple ultrasound pulse firings of either alternating phase and/or amplitude to detect nonlinear fundamental and subharmonic signals from microbubble contrast agents within living tissue, at high frequencies (- 15 MHz), e.g., with a linear array transducer. It can be shown that the contrast-to-tissue ratio (CTR) decreases with increasing ultrasound frequency because of nonlinear ultrasound propagation in tissue. However, using the subharmonic signal in addition to the nonlinear fundamental harmonic component, rather than the conventional second harmonic used at lower frequencies, provides appreciable signal strength to overcome the limitations of nonlinear tissue propagation. Additionally, the method provides for the ability to switch, at some desired frequency above 20 MHz, into a purely alternating phase inversion acquisition, in combination with bandpass filtering of the subharmonic frequency band, minimizing the losses in CTR as the frequency increases.
Abstract:
The invention relates to a method for detecting and imaging ultrasound echo signals returned from a target object comprising microbubbles, said microbubbles being characterized by a resonance frequency, said method comprising the steps of irradiating said target object with at least a first and second successive excitation signals, said first excitation signal being a sweep of increasing frequency with time, and said second excitation signal being a sweep of decreasing frequency with time, detecting echo signals of said first and second excitation signals from said target object, and, combining said echo signals. The maximum frequencies of said first and second excitation signals are lower than said resonance frequency. The invention also relates to an imaging apparatus.
Abstract:
A method and ultrasonic diagnostic imaging system for contrast agent imaging or tissue harmonic imaging is described which modulates the transmit power as a function of the angle of an electronically steered beam or the location of the beam in the scan plane to compensate for the reduction in delivered energy to points in the image field resulting from off-angle steering or a reduction in the number of elements of the transmit aperture.
Abstract:
A medical diagnostic ultrasound imaging system (10) acquires receive beams from spatially distinct transmit beams (40). The receive beams alternate in type between at least first, and second types (42, 46) across the region being imaged. The first, and second types of receive beams differ in at least one scan parameter other than transmit, receive line geometry, and can for example differ in transmit phase, transmit or receive aperture, system frequency or transmit focus. Predetection receive beams associated with spatially distinct ones of the transmit beams (including at least one beam of the first type, and at least one beam of the second type) are then preferably combined (48) in a coherent manner. In this way two-pulse phase inversion techniques, synthetic aperture techniques, synthetic frequency techniques, and synthetic focus techniques can be used while substantially reducing the frame rate penalty normally associated with such techniques.
Abstract:
Various approaches to generating and maintaining an ultrasound focus at a target region include configuring a controller to cause transmission of treatment ultrasound pulses from a transducer having multiple transducer elements; cause the transducer to transmit focusing ultrasound pulses to the target region and generate an acoustic reflector therein; measure reflections of the focusing ultrasound pulses from the acoustic reflector; based at least in part on the measured reflections, adjust a parameter value associated with one or more transducer elements so as to maintain and/or improve the ultrasound focus at the target region.
Abstract:
An ultrasonic diagnostic imaging system produces contrast enhanced images which are processed differently during different stages of contrast agent wash-in. During an initial stage of contrast wash-in, imaging is done using pixels processed by maximum intensity detection, to better reflect the rapid change in contrast intensity. During a later stage of contrast wash-in, time averaged processing is used to diminish the effects of noise and motion on the pixel values. During an intermediate period of peak enhancement, a combination of both pixel values processed by both techniques is used. In another aspect, a wash-in period can be characterized by an appearance stage, a growth stage and a peak stage, in which contrast pixel data is adaptively processed in different ways during these periods.
Abstract:
A subject information acquisition apparatus includes a converter configured to receive reflected waves from a contrast medium within a target area inside a subject, and a pressure information acquisition unit configured to acquire pressure information within the target area. In this case, the converter receives reflected waves from a contrast medium in each of a first period and a second period in which a pressure within the target area is different from the first period. The pressure information acquisition unit acquires pressure information in the second period within the target area based on a receive signal based on reflected waves in the first period, a receive signal based on a reflected wave in the second period, and pressure information on a region different from the target area, the pressure information being acquired in the first period.